crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.475 2018/02/23 15:58:38 markus 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/socket.h>
  53 #include <sys/wait.h>
  54
  55 #include <ctype.h>
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #include <netdb.h>
  59 #ifdef HAVE_PATHS_H
  60 #include <paths.h>
  61 #endif
  62 #include <pwd.h>
  63 #include <signal.h>
  64 #include <stdarg.h>
  65 #include <stddef.h>
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68 #include <string.h>
  69 #include <unistd.h>
  70 #include <limits.h>
  71 #include <locale.h>
  72
  73 #include <netinet/in.h>
  74 #include <arpa/inet.h>
  75
  76 #ifdef WITH_OPENSSL
  77 #include <openssl/evp.h>
  78 #include <openssl/err.h>
  79 #endif
  80 #include "openbsd-compat/openssl-compat.h"
  81 #include "openbsd-compat/sys-queue.h"
  82
  83 #include "xmalloc.h"
  84 #include "ssh.h"
  85 #include "ssh2.h"
  86 #include "canohost.h"
  87 #include "compat.h"
  88 #include "cipher.h"
  89 #include "digest.h"
  90 #include "packet.h"
  91 #include "buffer.h"
  92 #include "channels.h"
  93 #include "key.h"
  94 #include "authfd.h"
  95 #include "authfile.h"
  96 #include "pathnames.h"
  97 #include "dispatch.h"
  98 #include "clientloop.h"
  99 #include "log.h"
 100 #include "misc.h"
 101 #include "readconf.h"
 102 #include "sshconnect.h"
 103 #include "kex.h"
 104 #include "mac.h"
 105 #include "sshpty.h"
 106 #include "match.h"
 107 #include "msg.h"
 108 #include "uidswap.h"
 109 #include "version.h"
 110 #include "ssherr.h"
 111 #include "myproposal.h"
 112 #include "utf8.h"
 113
 114 #ifdef ENABLE_PKCS11
 115 #include "ssh-pkcs11.h"
 116 #endif
 117
 118 extern char *__progname;
 119
 120 /* Saves a copy of argv for setproctitle emulation */
 121 #ifndef HAVE_SETPROCTITLE
 122 static char **saved_av;
 123 #endif
 124
 125 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 126 int debug_flag = 0;
 127
 128 /* Flag indicating whether a tty should be requested */
 129 int tty_flag = 0;
 130
 131 /* don't exec a shell */
 132 int no_shell_flag = 0;
 133
 134 /*
 135  * Flag indicating that nothing should be read from stdin.  This can be set
 136  * on the command line.
 137  */
 138 int stdin_null_flag = 0;
 139
 140 /*
 141  * Flag indicating that the current process should be backgrounded and
 142  * a new slave launched in the foreground for ControlPersist.
 143  */
 144 int need_controlpersist_detach = 0;
 145
 146 /* Copies of flags for ControlPersist foreground slave */
 147 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 148
 149 /*
 150  * Flag indicating that ssh should fork after authentication.  This is useful
 151  * so that the passphrase can be entered manually, and then ssh goes to the
 152  * background.
 153  */
 154 int fork_after_authentication_flag = 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 /* Various strings used to to percent_expand() arguments */
 173 static char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 174 static char uidstr[32], *host_arg, *conn_hash_hex;
 175
 176 /* socket address the host resolves to */
 177 struct sockaddr_storage hostaddr;
 178
 179 /* Private host keys. */
 180 Sensitive sensitive_data;
 181
 182 /* Original real UID. */
 183 uid_t original_real_uid;
 184 uid_t original_effective_uid;
 185
 186 /* command to be executed */
 187 Buffer command;
 188
 189 /* Should we execute a command or invoke a subsystem? */
 190 int subsystem_flag = 0;
 191
 192 /* # of replies received for global requests */
 193 static int remote_forward_confirms_received = 0;
 194
 195 /* mux.c */
 196 extern int muxserver_sock;
 197 extern u_int muxclient_command;
 198
 199 /* Prints a help message to the user.  This function never returns. */
 200
 201 static void
 202 usage(void)
 203 {
 204         fprintf(stderr,
 205 "usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
 206 "           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
 207 "           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
 208 "           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
 209 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 210 "           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
 211 "           [-w local_tun[:remote_tun]] destination [command]\n"
 212         );
 213         exit(255);
 214 }
 215
 216 static int ssh_session2(struct ssh *, struct passwd *);
 217 static void load_public_identity_files(struct passwd *);
 218 static void main_sigchld_handler(int);
 219
 220 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 221 static void
 222 tilde_expand_paths(char **paths, u_int num_paths)
 223 {
 224         u_int i;
 225         char *cp;
 226
 227         for (i = 0; i < num_paths; i++) {
 228                 cp = tilde_expand_filename(paths[i], original_real_uid);
 229                 free(paths[i]);
 230                 paths[i] = cp;
 231         }
 232 }
 233
 234 /*
 235  * Attempt to resolve a host name / port to a set of addresses and
 236  * optionally return any CNAMEs encountered along the way.
 237  * Returns NULL on failure.
 238  * NB. this function must operate with a options having undefined members.
 239  */
 240 static struct addrinfo *
 241 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 242 {
 243         char strport[NI_MAXSERV];
 244         struct addrinfo hints, *res;
 245         int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
 246
 247         if (port <= 0)
 248                 port = default_ssh_port();
 249
 250         snprintf(strport, sizeof strport, "%d", port);
 251         memset(&hints, 0, sizeof(hints));
 252         hints.ai_family = options.address_family == -1 ?
 253             AF_UNSPEC : options.address_family;
 254         hints.ai_socktype = SOCK_STREAM;
 255         if (cname != NULL)
 256                 hints.ai_flags = AI_CANONNAME;
 257         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 258                 if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
 259                         loglevel = SYSLOG_LEVEL_ERROR;
 260                 do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
 261                     __progname, name, ssh_gai_strerror(gaierr));
 262                 return NULL;
 263         }
 264         if (cname != NULL && res->ai_canonname != NULL) {
 265                 if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
 266                         error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
 267                             __func__, name,  res->ai_canonname, (u_long)clen);
 268                         if (clen > 0)
 269                                 *cname = '\0';
 270                 }
 271         }
 272         return res;
 273 }
 274
 275 /* Returns non-zero if name can only be an address and not a hostname */
 276 static int
 277 is_addr_fast(const char *name)
 278 {
 279         return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
 280             strspn(name, "0123456789.") == strlen(name));
 281 }
 282
 283 /* Returns non-zero if name represents a valid, single address */
 284 static int
 285 is_addr(const char *name)
 286 {
 287         char strport[NI_MAXSERV];
 288         struct addrinfo hints, *res;
 289
 290         if (is_addr_fast(name))
 291                 return 1;
 292
 293         snprintf(strport, sizeof strport, "%u", default_ssh_port());
 294         memset(&hints, 0, sizeof(hints));
 295         hints.ai_family = options.address_family == -1 ?
 296             AF_UNSPEC : options.address_family;
 297         hints.ai_socktype = SOCK_STREAM;
 298         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
 299         if (getaddrinfo(name, strport, &hints, &res) != 0)
 300                 return 0;
 301         if (res == NULL || res->ai_next != NULL) {
 302                 freeaddrinfo(res);
 303                 return 0;
 304         }
 305         freeaddrinfo(res);
 306         return 1;
 307 }
 308
 309 /*
 310  * Attempt to resolve a numeric host address / port to a single address.
 311  * Returns a canonical address string.
 312  * Returns NULL on failure.
 313  * NB. this function must operate with a options having undefined members.
 314  */
 315 static struct addrinfo *
 316 resolve_addr(const char *name, int port, char *caddr, size_t clen)
 317 {
 318         char addr[NI_MAXHOST], strport[NI_MAXSERV];
 319         struct addrinfo hints, *res;
 320         int gaierr;
 321
 322         if (port <= 0)
 323                 port = default_ssh_port();
 324         snprintf(strport, sizeof strport, "%u", port);
 325         memset(&hints, 0, sizeof(hints));
 326         hints.ai_family = options.address_family == -1 ?
 327             AF_UNSPEC : options.address_family;
 328         hints.ai_socktype = SOCK_STREAM;
 329         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
 330         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 331                 debug2("%s: could not resolve name %.100s as address: %s",
 332                     __func__, name, ssh_gai_strerror(gaierr));
 333                 return NULL;
 334         }
 335         if (res == NULL) {
 336                 debug("%s: getaddrinfo %.100s returned no addresses",
 337                  __func__, name);
 338                 return NULL;
 339         }
 340         if (res->ai_next != NULL) {
 341                 debug("%s: getaddrinfo %.100s returned multiple addresses",
 342                     __func__, name);
 343                 goto fail;
 344         }
 345         if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
 346             addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
 347                 debug("%s: Could not format address for name %.100s: %s",
 348                     __func__, name, ssh_gai_strerror(gaierr));
 349                 goto fail;
 350         }
 351         if (strlcpy(caddr, addr, clen) >= clen) {
 352                 error("%s: host \"%s\" addr \"%s\" too long (max %lu)",
 353                     __func__, name,  addr, (u_long)clen);
 354                 if (clen > 0)
 355                         *caddr = '\0';
 356  fail:
 357                 freeaddrinfo(res);
 358                 return NULL;
 359         }
 360         return res;
 361 }
 362
 363 /*
 364  * Check whether the cname is a permitted replacement for the hostname
 365  * and perform the replacement if it is.
 366  * NB. this function must operate with a options having undefined members.
 367  */
 368 static int
 369 check_follow_cname(int direct, char **namep, const char *cname)
 370 {
 371         int i;
 372         struct allowed_cname *rule;
 373
 374         if (*cname == '\0' || options.num_permitted_cnames == 0 ||
 375             strcmp(*namep, cname) == 0)
 376                 return 0;
 377         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 378                 return 0;
 379         /*
 380          * Don't attempt to canonicalize names that will be interpreted by
 381          * a proxy or jump host unless the user specifically requests so.
 382          */
 383         if (!direct &&
 384             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 385                 return 0;
 386         debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
 387         for (i = 0; i < options.num_permitted_cnames; i++) {
 388                 rule = options.permitted_cnames + i;
 389                 if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
 390                     match_pattern_list(cname, rule->target_list, 1) != 1)
 391                         continue;
 392                 verbose("Canonicalized DNS aliased hostname "
 393                     "\"%s\" => \"%s\"", *namep, cname);
 394                 free(*namep);
 395                 *namep = xstrdup(cname);
 396                 return 1;
 397         }
 398         return 0;
 399 }
 400
 401 /*
 402  * Attempt to resolve the supplied hostname after applying the user's
 403  * canonicalization rules. Returns the address list for the host or NULL
 404  * if no name was found after canonicalization.
 405  * NB. this function must operate with a options having undefined members.
 406  */
 407 static struct addrinfo *
 408 resolve_canonicalize(char **hostp, int port)
 409 {
 410         int i, direct, ndots;
 411         char *cp, *fullhost, newname[NI_MAXHOST];
 412         struct addrinfo *addrs;
 413
 414         /*
 415          * Attempt to canonicalise addresses, regardless of
 416          * whether hostname canonicalisation was requested
 417          */
 418         if ((addrs = resolve_addr(*hostp, port,
 419             newname, sizeof(newname))) != NULL) {
 420                 debug2("%s: hostname %.100s is address", __func__, *hostp);
 421                 if (strcasecmp(*hostp, newname) != 0) {
 422                         debug2("%s: canonicalised address \"%s\" => \"%s\"",
 423                             __func__, *hostp, newname);
 424                         free(*hostp);
 425                         *hostp = xstrdup(newname);
 426                 }
 427                 return addrs;
 428         }
 429
 430         /*
 431          * If this looks like an address but didn't parse as one, it might
 432          * be an address with an invalid interface scope. Skip further
 433          * attempts at canonicalisation.
 434          */
 435         if (is_addr_fast(*hostp)) {
 436                 debug("%s: hostname %.100s is an unrecognised address",
 437                     __func__, *hostp);
 438                 return NULL;
 439         }
 440
 441         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 442                 return NULL;
 443
 444         /*
 445          * Don't attempt to canonicalize names that will be interpreted by
 446          * a proxy unless the user specifically requests so.
 447          */
 448         direct = option_clear_or_none(options.proxy_command) &&
 449             options.jump_host == NULL;
 450         if (!direct &&
 451             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 452                 return NULL;
 453
 454         /* If domain name is anchored, then resolve it now */
 455         if ((*hostp)[strlen(*hostp) - 1] == '.') {
 456                 debug3("%s: name is fully qualified", __func__);
 457                 fullhost = xstrdup(*hostp);
 458                 if ((addrs = resolve_host(fullhost, port, 0,
 459                     newname, sizeof(newname))) != NULL)
 460                         goto found;
 461                 free(fullhost);
 462                 goto notfound;
 463         }
 464
 465         /* Don't apply canonicalization to sufficiently-qualified hostnames */
 466         ndots = 0;
 467         for (cp = *hostp; *cp != '\0'; cp++) {
 468                 if (*cp == '.')
 469                         ndots++;
 470         }
 471         if (ndots > options.canonicalize_max_dots) {
 472                 debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
 473                     __func__, *hostp, options.canonicalize_max_dots);
 474                 return NULL;
 475         }
 476         /* Attempt each supplied suffix */
 477         for (i = 0; i < options.num_canonical_domains; i++) {
 478                 *newname = '\0';
 479                 xasprintf(&fullhost, "%s.%s.", *hostp,
 480                     options.canonical_domains[i]);
 481                 debug3("%s: attempting \"%s\" => \"%s\"", __func__,
 482                     *hostp, fullhost);
 483                 if ((addrs = resolve_host(fullhost, port, 0,
 484                     newname, sizeof(newname))) == NULL) {
 485                         free(fullhost);
 486                         continue;
 487                 }
 488  found:
 489                 /* Remove trailing '.' */
 490                 fullhost[strlen(fullhost) - 1] = '\0';
 491                 /* Follow CNAME if requested */
 492                 if (!check_follow_cname(direct, &fullhost, newname)) {
 493                         debug("Canonicalized hostname \"%s\" => \"%s\"",
 494                             *hostp, fullhost);
 495                 }
 496                 free(*hostp);
 497                 *hostp = fullhost;
 498                 return addrs;
 499         }
 500  notfound:
 501         if (!options.canonicalize_fallback_local)
 502                 fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
 503         debug2("%s: host %s not found in any suffix", __func__, *hostp);
 504         return NULL;
 505 }
 506
 507 /*
 508  * Read per-user configuration file.  Ignore the system wide config
 509  * file if the user specifies a config file on the command line.
 510  */
 511 static void
 512 process_config_files(const char *host_name, struct passwd *pw, int post_canon)
 513 {
 514         char buf[PATH_MAX];
 515         int r;
 516
 517         if (config != NULL) {
 518                 if (strcasecmp(config, "none") != 0 &&
 519                     !read_config_file(config, pw, host, host_name, &options,
 520                     SSHCONF_USERCONF | (post_canon ? SSHCONF_POSTCANON : 0)))
 521                         fatal("Can't open user config file %.100s: "
 522                             "%.100s", config, strerror(errno));
 523         } else {
 524                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 525                     _PATH_SSH_USER_CONFFILE);
 526                 if (r > 0 && (size_t)r < sizeof(buf))
 527                         (void)read_config_file(buf, pw, host, host_name,
 528                             &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
 529                             (post_canon ? SSHCONF_POSTCANON : 0));
 530
 531                 /* Read systemwide configuration file after user config. */
 532                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
 533                     host, host_name, &options,
 534                     post_canon ? SSHCONF_POSTCANON : 0);
 535         }
 536 }
 537
 538 /* Rewrite the port number in an addrinfo list of addresses */
 539 static void
 540 set_addrinfo_port(struct addrinfo *addrs, int port)
 541 {
 542         struct addrinfo *addr;
 543
 544         for (addr = addrs; addr != NULL; addr = addr->ai_next) {
 545                 switch (addr->ai_family) {
 546                 case AF_INET:
 547                         ((struct sockaddr_in *)addr->ai_addr)->
 548                             sin_port = htons(port);
 549                         break;
 550                 case AF_INET6:
 551                         ((struct sockaddr_in6 *)addr->ai_addr)->
 552                             sin6_port = htons(port);
 553                         break;
 554                 }
 555         }
 556 }
 557
 558 /*
 559  * Main program for the ssh client.
 560  */
 561 int
 562 main(int ac, char **av)
 563 {
 564         struct ssh *ssh = NULL;
 565         int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
 566         int was_addr, config_test = 0, opt_terminated = 0;
 567         char *p, *cp, *line, *argv0, buf[PATH_MAX], *logfile;
 568         char cname[NI_MAXHOST];
 569         struct stat st;
 570         struct passwd *pw;
 571         extern int optind, optreset;
 572         extern char *optarg;
 573         struct Forward fwd;
 574         struct addrinfo *addrs = NULL;
 575         struct ssh_digest_ctx *md;
 576         u_char conn_hash[SSH_DIGEST_MAX_LENGTH];
 577
 578         ssh_malloc_init();      /* must be called before any mallocs */
 579         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 580         sanitise_stdfd();
 581
 582         __progname = ssh_get_progname(av[0]);
 583
 584 #ifndef HAVE_SETPROCTITLE
 585         /* Prepare for later setproctitle emulation */
 586         /* Save argv so it isn't clobbered by setproctitle() emulation */
 587         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 588         for (i = 0; i < ac; i++)
 589                 saved_av[i] = xstrdup(av[i]);
 590         saved_av[i] = NULL;
 591         compat_init_setproctitle(ac, av);
 592         av = saved_av;
 593 #endif
 594
 595         /*
 596          * Discard other fds that are hanging around. These can cause problem
 597          * with backgrounded ssh processes started by ControlPersist.
 598          */
 599         closefrom(STDERR_FILENO + 1);
 600
 601         /*
 602          * Save the original real uid.  It will be needed later (uid-swapping
 603          * may clobber the real uid).
 604          */
 605         original_real_uid = getuid();
 606         original_effective_uid = geteuid();
 607
 608         /*
 609          * Use uid-swapping to give up root privileges for the duration of
 610          * option processing.  We will re-instantiate the rights when we are
 611          * ready to create the privileged port, and will permanently drop
 612          * them when the port has been created (actually, when the connection
 613          * has been made, as we may need to create the port several times).
 614          */
 615         PRIV_END;
 616
 617 #ifdef HAVE_SETRLIMIT
 618         /* If we are installed setuid root be careful to not drop core. */
 619         if (original_real_uid != original_effective_uid) {
 620                 struct rlimit rlim;
 621                 rlim.rlim_cur = rlim.rlim_max = 0;
 622                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 623                         fatal("setrlimit failed: %.100s", strerror(errno));
 624         }
 625 #endif
 626         /* Get user data. */
 627         pw = getpwuid(original_real_uid);
 628         if (!pw) {
 629                 logit("No user exists for uid %lu", (u_long)original_real_uid);
 630                 exit(255);
 631         }
 632         /* Take a copy of the returned structure. */
 633         pw = pwcopy(pw);
 634
 635         /*
 636          * Set our umask to something reasonable, as some files are created
 637          * with the default umask.  This will make them world-readable but
 638          * writable only by the owner, which is ok for all files for which we
 639          * don't set the modes explicitly.
 640          */
 641         umask(022);
 642
 643         msetlocale();
 644
 645         /*
 646          * Initialize option structure to indicate that no values have been
 647          * set.
 648          */
 649         initialize_options(&options);
 650
 651         /*
 652          * Prepare main ssh transport/connection structures
 653          */
 654         if ((ssh = ssh_alloc_session_state()) == NULL)
 655                 fatal("Couldn't allocate session state");
 656         channel_init_channels(ssh);
 657         active_state = ssh; /* XXX legacy API compat */
 658
 659         /* Parse command-line arguments. */
 660         host = NULL;
 661         use_syslog = 0;
 662         logfile = NULL;
 663         argv0 = av[0];
 664
 665  again:
 666         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 667             "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
 668                 switch (opt) {
 669                 case '1':
 670                         fatal("SSH protocol v.1 is no longer supported");
 671                         break;
 672                 case '2':
 673                         /* Ignored */
 674                         break;
 675                 case '4':
 676                         options.address_family = AF_INET;
 677                         break;
 678                 case '6':
 679                         options.address_family = AF_INET6;
 680                         break;
 681                 case 'n':
 682                         stdin_null_flag = 1;
 683                         break;
 684                 case 'f':
 685                         fork_after_authentication_flag = 1;
 686                         stdin_null_flag = 1;
 687                         break;
 688                 case 'x':
 689                         options.forward_x11 = 0;
 690                         break;
 691                 case 'X':
 692                         options.forward_x11 = 1;
 693                         break;
 694                 case 'y':
 695                         use_syslog = 1;
 696                         break;
 697                 case 'E':
 698                         logfile = optarg;
 699                         break;
 700                 case 'G':
 701                         config_test = 1;
 702                         break;
 703                 case 'Y':
 704                         options.forward_x11 = 1;
 705                         options.forward_x11_trusted = 1;
 706                         break;
 707                 case 'g':
 708                         options.fwd_opts.gateway_ports = 1;
 709                         break;
 710                 case 'O':
 711                         if (options.stdio_forward_host != NULL)
 712                                 fatal("Cannot specify multiplexing "
 713                                     "command with -W");
 714                         else if (muxclient_command != 0)
 715                                 fatal("Multiplexing command already specified");
 716                         if (strcmp(optarg, "check") == 0)
 717                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 718                         else if (strcmp(optarg, "forward") == 0)
 719                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 720                         else if (strcmp(optarg, "exit") == 0)
 721                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 722                         else if (strcmp(optarg, "stop") == 0)
 723                                 muxclient_command = SSHMUX_COMMAND_STOP;
 724                         else if (strcmp(optarg, "cancel") == 0)
 725                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 726                         else if (strcmp(optarg, "proxy") == 0)
 727                                 muxclient_command = SSHMUX_COMMAND_PROXY;
 728                         else
 729                                 fatal("Invalid multiplex command.");
 730                         break;
 731                 case 'P':       /* deprecated */
 732                         options.use_privileged_port = 0;
 733                         break;
 734                 case 'Q':
 735                         cp = NULL;
 736                         if (strcmp(optarg, "cipher") == 0)
 737                                 cp = cipher_alg_list('\n', 0);
 738                         else if (strcmp(optarg, "cipher-auth") == 0)
 739                                 cp = cipher_alg_list('\n', 1);
 740                         else if (strcmp(optarg, "mac") == 0)
 741                                 cp = mac_alg_list('\n');
 742                         else if (strcmp(optarg, "kex") == 0)
 743                                 cp = kex_alg_list('\n');
 744                         else if (strcmp(optarg, "key") == 0)
 745                                 cp = sshkey_alg_list(0, 0, 0, '\n');
 746                         else if (strcmp(optarg, "key-cert") == 0)
 747                                 cp = sshkey_alg_list(1, 0, 0, '\n');
 748                         else if (strcmp(optarg, "key-plain") == 0)
 749                                 cp = sshkey_alg_list(0, 1, 0, '\n');
 750                         else if (strcmp(optarg, "protocol-version") == 0) {
 751                                 cp = xstrdup("2");
 752                         }
 753                         if (cp == NULL)
 754                                 fatal("Unsupported query \"%s\"", optarg);
 755                         printf("%s\n", cp);
 756                         free(cp);
 757                         exit(0);
 758                         break;
 759                 case 'a':
 760                         options.forward_agent = 0;
 761                         break;
 762                 case 'A':
 763                         options.forward_agent = 1;
 764                         break;
 765                 case 'k':
 766                         options.gss_deleg_creds = 0;
 767                         break;
 768                 case 'K':
 769                         options.gss_authentication = 1;
 770                         options.gss_deleg_creds = 1;
 771                         break;
 772                 case 'i':
 773                         p = tilde_expand_filename(optarg, original_real_uid);
 774                         if (stat(p, &st) < 0)
 775                                 fprintf(stderr, "Warning: Identity file %s "
 776                                     "not accessible: %s.\n", p,
 777                                     strerror(errno));
 778                         else
 779                                 add_identity_file(&options, NULL, p, 1);
 780                         free(p);
 781                         break;
 782                 case 'I':
 783 #ifdef ENABLE_PKCS11
 784                         free(options.pkcs11_provider);
 785                         options.pkcs11_provider = xstrdup(optarg);
 786 #else
 787                         fprintf(stderr, "no support for PKCS#11.\n");
 788 #endif
 789                         break;
 790                 case 'J':
 791                         if (options.jump_host != NULL)
 792                                 fatal("Only a single -J option permitted");
 793                         if (options.proxy_command != NULL)
 794                                 fatal("Cannot specify -J with ProxyCommand");
 795                         if (parse_jump(optarg, &options, 1) == -1)
 796                                 fatal("Invalid -J argument");
 797                         options.proxy_command = xstrdup("none");
 798                         break;
 799                 case 't':
 800                         if (options.request_tty == REQUEST_TTY_YES)
 801                                 options.request_tty = REQUEST_TTY_FORCE;
 802                         else
 803                                 options.request_tty = REQUEST_TTY_YES;
 804                         break;
 805                 case 'v':
 806                         if (debug_flag == 0) {
 807                                 debug_flag = 1;
 808                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 809                         } else {
 810                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
 811                                         debug_flag++;
 812                                         options.log_level++;
 813                                 }
 814                         }
 815                         break;
 816                 case 'V':
 817                         if (options.version_addendum &&
 818                             *options.version_addendum != '\0')
 819                                 fprintf(stderr, "%s %s, %s\n", SSH_RELEASE,
 820                                     options.version_addendum,
 821                                     OPENSSL_VERSION);
 822                         else
 823                                 fprintf(stderr, "%s, %s\n", SSH_RELEASE,
 824                                     OPENSSL_VERSION);
 825                         if (opt == 'V')
 826                                 exit(0);
 827                         break;
 828                 case 'w':
 829                         if (options.tun_open == -1)
 830                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 831                         options.tun_local = a2tun(optarg, &options.tun_remote);
 832                         if (options.tun_local == SSH_TUNID_ERR) {
 833                                 fprintf(stderr,
 834                                     "Bad tun device '%s'\n", optarg);
 835                                 exit(255);
 836                         }
 837                         break;
 838                 case 'W':
 839                         if (options.stdio_forward_host != NULL)
 840                                 fatal("stdio forward already specified");
 841                         if (muxclient_command != 0)
 842                                 fatal("Cannot specify stdio forward with -O");
 843                         if (parse_forward(&fwd, optarg, 1, 0)) {
 844                                 options.stdio_forward_host = fwd.listen_host;
 845                                 options.stdio_forward_port = fwd.listen_port;
 846                                 free(fwd.connect_host);
 847                         } else {
 848                                 fprintf(stderr,
 849                                     "Bad stdio forwarding specification '%s'\n",
 850                                     optarg);
 851                                 exit(255);
 852                         }
 853                         options.request_tty = REQUEST_TTY_NO;
 854                         no_shell_flag = 1;
 855                         break;
 856                 case 'q':
 857                         options.log_level = SYSLOG_LEVEL_QUIET;
 858                         break;
 859                 case 'e':
 860                         if (optarg[0] == '^' && optarg[2] == 0 &&
 861                             (u_char) optarg[1] >= 64 &&
 862                             (u_char) optarg[1] < 128)
 863                                 options.escape_char = (u_char) optarg[1] & 31;
 864                         else if (strlen(optarg) == 1)
 865                                 options.escape_char = (u_char) optarg[0];
 866                         else if (strcmp(optarg, "none") == 0)
 867                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 868                         else {
 869                                 fprintf(stderr, "Bad escape character '%s'.\n",
 870                                     optarg);
 871                                 exit(255);
 872                         }
 873                         break;
 874                 case 'c':
 875                         if (!ciphers_valid(*optarg == '+' ?
 876                             optarg + 1 : optarg)) {
 877                                 fprintf(stderr, "Unknown cipher type '%s'\n",
 878                                     optarg);
 879                                 exit(255);
 880                         }
 881                         free(options.ciphers);
 882                         options.ciphers = xstrdup(optarg);
 883                         break;
 884                 case 'm':
 885                         if (mac_valid(optarg)) {
 886                                 free(options.macs);
 887                                 options.macs = xstrdup(optarg);
 888                         } else {
 889                                 fprintf(stderr, "Unknown mac type '%s'\n",
 890                                     optarg);
 891                                 exit(255);
 892                         }
 893                         break;
 894                 case 'M':
 895                         if (options.control_master == SSHCTL_MASTER_YES)
 896                                 options.control_master = SSHCTL_MASTER_ASK;
 897                         else
 898                                 options.control_master = SSHCTL_MASTER_YES;
 899                         break;
 900                 case 'p':
 901                         if (options.port == -1) {
 902                                 options.port = a2port(optarg);
 903                                 if (options.port <= 0) {
 904                                         fprintf(stderr, "Bad port '%s'\n",
 905                                             optarg);
 906                                         exit(255);
 907                                 }
 908                         }
 909                         break;
 910                 case 'l':
 911                         if (options.user == NULL)
 912                                 options.user = optarg;
 913                         break;
 914
 915                 case 'L':
 916                         if (parse_forward(&fwd, optarg, 0, 0))
 917                                 add_local_forward(&options, &fwd);
 918                         else {
 919                                 fprintf(stderr,
 920                                     "Bad local forwarding specification '%s'\n",
 921                                     optarg);
 922                                 exit(255);
 923                         }
 924                         break;
 925
 926                 case 'R':
 927                         if (parse_forward(&fwd, optarg, 0, 1) ||
 928                             parse_forward(&fwd, optarg, 1, 1)) {
 929                                 add_remote_forward(&options, &fwd);
 930                         } else {
 931                                 fprintf(stderr,
 932                                     "Bad remote forwarding specification "
 933                                     "'%s'\n", optarg);
 934                                 exit(255);
 935                         }
 936                         break;
 937
 938                 case 'D':
 939                         if (parse_forward(&fwd, optarg, 1, 0)) {
 940                                 add_local_forward(&options, &fwd);
 941                         } else {
 942                                 fprintf(stderr,
 943                                     "Bad dynamic forwarding specification "
 944                                     "'%s'\n", optarg);
 945                                 exit(255);
 946                         }
 947                         break;
 948
 949                 case 'C':
 950                         options.compression = 1;
 951                         break;
 952                 case 'N':
 953                         no_shell_flag = 1;
 954                         options.request_tty = REQUEST_TTY_NO;
 955                         break;
 956                 case 'T':
 957                         options.request_tty = REQUEST_TTY_NO;
 958                         break;
 959                 case 'o':
 960                         line = xstrdup(optarg);
 961                         if (process_config_line(&options, pw,
 962                             host ? host : "", host ? host : "", line,
 963                             "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
 964                                 exit(255);
 965                         free(line);
 966                         break;
 967                 case 's':
 968                         subsystem_flag = 1;
 969                         break;
 970                 case 'S':
 971                         free(options.control_path);
 972                         options.control_path = xstrdup(optarg);
 973                         break;
 974                 case 'b':
 975                         options.bind_address = optarg;
 976                         break;
 977                 case 'B':
 978                         options.bind_interface = optarg;
 979                         break;
 980                 case 'F':
 981                         config = optarg;
 982                         break;
 983                 default:
 984                         usage();
 985                 }
 986         }
 987
 988         if (optind > 1 && strcmp(av[optind - 1], "--") == 0)
 989                 opt_terminated = 1;
 990
 991         ac -= optind;
 992         av += optind;
 993
 994         if (ac > 0 && !host) {
 995                 int tport;
 996                 char *tuser;
 997                 switch (parse_ssh_uri(*av, &tuser, &host, &tport)) {
 998                 case -1:
 999                         usage();
1000                         break;
1001                 case 0:
1002                         if (options.user == NULL) {
1003                                 options.user = tuser;
1004                                 tuser = NULL;
1005                         }
1006                         free(tuser);
1007                         if (options.port == -1 && tport != -1)
1008                                 options.port = tport;
1009                         break;
1010                 default:
1011                         p = xstrdup(*av);
1012                         cp = strrchr(p, '@');
1013                         if (cp != NULL) {
1014                                 if (cp == p)
1015                                         usage();
1016                                 if (options.user == NULL) {
1017                                         options.user = p;
1018                                         p = NULL;
1019                                 }
1020                                 *cp++ = '\0';
1021                                 host = xstrdup(cp);
1022                                 free(p);
1023                         } else
1024                                 host = p;
1025                         break;
1026                 }
1027                 if (ac > 1 && !opt_terminated) {
1028                         optind = optreset = 1;
1029                         goto again;
1030                 }
1031                 ac--, av++;
1032         }
1033
1034         /* Check that we got a host name. */
1035         if (!host)
1036                 usage();
1037
1038         host_arg = xstrdup(host);
1039
1040 #ifdef WITH_OPENSSL
1041         OpenSSL_add_all_algorithms();
1042         ERR_load_crypto_strings();
1043 #endif
1044
1045         /* Initialize the command to execute on remote host. */
1046         buffer_init(&command);
1047
1048         /*
1049          * Save the command to execute on the remote host in a buffer. There
1050          * is no limit on the length of the command, except by the maximum
1051          * packet size.  Also sets the tty flag if there is no command.
1052          */
1053         if (!ac) {
1054                 /* No command specified - execute shell on a tty. */
1055                 if (subsystem_flag) {
1056                         fprintf(stderr,
1057                             "You must specify a subsystem to invoke.\n");
1058                         usage();
1059                 }
1060         } else {
1061                 /* A command has been specified.  Store it into the buffer. */
1062                 for (i = 0; i < ac; i++) {
1063                         if (i)
1064                                 buffer_append(&command, " ", 1);
1065                         buffer_append(&command, av[i], strlen(av[i]));
1066                 }
1067         }
1068
1069         /*
1070          * Initialize "log" output.  Since we are the client all output
1071          * goes to stderr unless otherwise specified by -y or -E.
1072          */
1073         if (use_syslog && logfile != NULL)
1074                 fatal("Can't specify both -y and -E");
1075         if (logfile != NULL)
1076                 log_redirect_stderr_to(logfile);
1077         log_init(argv0,
1078             options.log_level == SYSLOG_LEVEL_NOT_SET ?
1079             SYSLOG_LEVEL_INFO : options.log_level,
1080             options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1081             SYSLOG_FACILITY_USER : options.log_facility,
1082             !use_syslog);
1083
1084         if (debug_flag)
1085                 /* version_addendum is always NULL at this point */
1086                 logit("%s, %s", SSH_RELEASE, OPENSSL_VERSION);
1087
1088         /* Parse the configuration files */
1089         process_config_files(host_arg, pw, 0);
1090
1091         /* Hostname canonicalisation needs a few options filled. */
1092         fill_default_options_for_canonicalization(&options);
1093
1094         /* If the user has replaced the hostname then take it into use now */
1095         if (options.hostname != NULL) {
1096                 /* NB. Please keep in sync with readconf.c:match_cfg_line() */
1097                 cp = percent_expand(options.hostname,
1098                     "h", host, (char *)NULL);
1099                 free(host);
1100                 host = cp;
1101                 free(options.hostname);
1102                 options.hostname = xstrdup(host);
1103         }
1104
1105         /* Don't lowercase addresses, they will be explicitly canonicalised */
1106         if ((was_addr = is_addr(host)) == 0)
1107                 lowercase(host);
1108
1109         /*
1110          * Try to canonicalize if requested by configuration or the
1111          * hostname is an address.
1112          */
1113         if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
1114                 addrs = resolve_canonicalize(&host, options.port);
1115
1116         /*
1117          * If CanonicalizePermittedCNAMEs have been specified but
1118          * other canonicalization did not happen (by not being requested
1119          * or by failing with fallback) then the hostname may still be changed
1120          * as a result of CNAME following.
1121          *
1122          * Try to resolve the bare hostname name using the system resolver's
1123          * usual search rules and then apply the CNAME follow rules.
1124          *
1125          * Skip the lookup if a ProxyCommand is being used unless the user
1126          * has specifically requested canonicalisation for this case via
1127          * CanonicalizeHostname=always
1128          */
1129         direct = option_clear_or_none(options.proxy_command) &&
1130             options.jump_host == NULL;
1131         if (addrs == NULL && options.num_permitted_cnames != 0 && (direct ||
1132             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1133                 if ((addrs = resolve_host(host, options.port,
1134                     option_clear_or_none(options.proxy_command),
1135                     cname, sizeof(cname))) == NULL) {
1136                         /* Don't fatal proxied host names not in the DNS */
1137                         if (option_clear_or_none(options.proxy_command))
1138                                 cleanup_exit(255); /* logged in resolve_host */
1139                 } else
1140                         check_follow_cname(direct, &host, cname);
1141         }
1142
1143         /*
1144          * If canonicalisation is enabled then re-parse the configuration
1145          * files as new stanzas may match.
1146          */
1147         if (options.canonicalize_hostname != 0) {
1148                 debug("Re-reading configuration after hostname "
1149                     "canonicalisation");
1150                 free(options.hostname);
1151                 options.hostname = xstrdup(host);
1152                 process_config_files(host_arg, pw, 1);
1153                 /*
1154                  * Address resolution happens early with canonicalisation
1155                  * enabled and the port number may have changed since, so
1156                  * reset it in address list
1157                  */
1158                 if (addrs != NULL && options.port > 0)
1159                         set_addrinfo_port(addrs, options.port);
1160         }
1161
1162         /* Fill configuration defaults. */
1163         fill_default_options(&options);
1164
1165         /*
1166          * If ProxyJump option specified, then construct a ProxyCommand now.
1167          */
1168         if (options.jump_host != NULL) {
1169                 char port_s[8];
1170
1171                 /* Consistency check */
1172                 if (options.proxy_command != NULL)
1173                         fatal("inconsistent options: ProxyCommand+ProxyJump");
1174                 /* Never use FD passing for ProxyJump */
1175                 options.proxy_use_fdpass = 0;
1176                 snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
1177                 xasprintf(&options.proxy_command,
1178                     "ssh%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
1179                     /* Optional "-l user" argument if jump_user set */
1180                     options.jump_user == NULL ? "" : " -l ",
1181                     options.jump_user == NULL ? "" : options.jump_user,
1182                     /* Optional "-p port" argument if jump_port set */
1183                     options.jump_port <= 0 ? "" : " -p ",
1184                     options.jump_port <= 0 ? "" : port_s,
1185                     /* Optional additional jump hosts ",..." */
1186                     options.jump_extra == NULL ? "" : " -J ",
1187                     options.jump_extra == NULL ? "" : options.jump_extra,
1188                     /* Optional "-F" argumment if -F specified */
1189                     config == NULL ? "" : " -F ",
1190                     config == NULL ? "" : config,
1191                     /* Optional "-v" arguments if -v set */
1192                     debug_flag ? " -" : "",
1193                     debug_flag, "vvv",
1194                     /* Mandatory hostname */
1195                     options.jump_host);
1196                 debug("Setting implicit ProxyCommand from ProxyJump: %s",
1197                     options.proxy_command);
1198         }
1199
1200         if (options.port == 0)
1201                 options.port = default_ssh_port();
1202         channel_set_af(ssh, options.address_family);
1203
1204         /* Tidy and check options */
1205         if (options.host_key_alias != NULL)
1206                 lowercase(options.host_key_alias);
1207         if (options.proxy_command != NULL &&
1208             strcmp(options.proxy_command, "-") == 0 &&
1209             options.proxy_use_fdpass)
1210                 fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1211         if (options.control_persist &&
1212             options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1213                 debug("UpdateHostKeys=ask is incompatible with ControlPersist; "
1214                     "disabling");
1215                 options.update_hostkeys = 0;
1216         }
1217         if (options.connection_attempts <= 0)
1218                 fatal("Invalid number of ConnectionAttempts");
1219 #ifndef HAVE_CYGWIN
1220         if (original_effective_uid != 0)
1221                 options.use_privileged_port = 0;
1222 #endif
1223
1224         if (buffer_len(&command) != 0 && options.remote_command != NULL)
1225                 fatal("Cannot execute command-line and remote command.");
1226
1227         /* Cannot fork to background if no command. */
1228         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
1229             options.remote_command == NULL && !no_shell_flag)
1230                 fatal("Cannot fork into background without a command "
1231                     "to execute.");
1232
1233         /* reinit */
1234         log_init(argv0, options.log_level, options.log_facility, !use_syslog);
1235
1236         if (options.request_tty == REQUEST_TTY_YES ||
1237             options.request_tty == REQUEST_TTY_FORCE)
1238                 tty_flag = 1;
1239
1240         /* Allocate a tty by default if no command specified. */
1241         if (buffer_len(&command) == 0 && options.remote_command == NULL)
1242                 tty_flag = options.request_tty != REQUEST_TTY_NO;
1243
1244         /* Force no tty */
1245         if (options.request_tty == REQUEST_TTY_NO ||
1246             (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
1247                 tty_flag = 0;
1248         /* Do not allocate a tty if stdin is not a tty. */
1249         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
1250             options.request_tty != REQUEST_TTY_FORCE) {
1251                 if (tty_flag)
1252                         logit("Pseudo-terminal will not be allocated because "
1253                             "stdin is not a terminal.");
1254                 tty_flag = 0;
1255         }
1256
1257         seed_rng();
1258
1259         if (options.user == NULL)
1260                 options.user = xstrdup(pw->pw_name);
1261
1262         /* Set up strings used to percent_expand() arguments */
1263         if (gethostname(thishost, sizeof(thishost)) == -1)
1264                 fatal("gethostname: %s", strerror(errno));
1265         strlcpy(shorthost, thishost, sizeof(shorthost));
1266         shorthost[strcspn(thishost, ".")] = '\0';
1267         snprintf(portstr, sizeof(portstr), "%d", options.port);
1268         snprintf(uidstr, sizeof(uidstr), "%d", pw->pw_uid);
1269
1270         /* Find canonic host name. */
1271         if (strchr(host, '.') == 0) {
1272                 struct addrinfo hints;
1273                 struct addrinfo *ai = NULL;
1274                 int errgai;
1275                 memset(&hints, 0, sizeof(hints));
1276                 hints.ai_family = options.address_family;
1277                 hints.ai_flags = AI_CANONNAME;
1278                 hints.ai_socktype = SOCK_STREAM;
1279                 errgai = getaddrinfo(host, NULL, &hints, &ai);
1280                 if (errgai == 0) {
1281                         if (ai->ai_canonname != NULL)
1282                                 host = xstrdup(ai->ai_canonname);
1283                         freeaddrinfo(ai);
1284                 }
1285         }
1286
1287         if ((md = ssh_digest_start(SSH_DIGEST_SHA1)) == NULL ||
1288             ssh_digest_update(md, thishost, strlen(thishost)) < 0 ||
1289             ssh_digest_update(md, host, strlen(host)) < 0 ||
1290             ssh_digest_update(md, portstr, strlen(portstr)) < 0 ||
1291             ssh_digest_update(md, options.user, strlen(options.user)) < 0 ||
1292             ssh_digest_final(md, conn_hash, sizeof(conn_hash)) < 0)
1293                 fatal("%s: mux digest failed", __func__);
1294         ssh_digest_free(md);
1295         conn_hash_hex = tohex(conn_hash, ssh_digest_bytes(SSH_DIGEST_SHA1));
1296
1297         /*
1298          * Expand tokens in arguments. NB. LocalCommand is expanded later,
1299          * after port-forwarding is set up, so it may pick up any local
1300          * tunnel interface name allocated.
1301          */
1302         if (options.remote_command != NULL) {
1303                 debug3("expanding RemoteCommand: %s", options.remote_command);
1304                 cp = options.remote_command;
1305                 options.remote_command = percent_expand(cp,
1306                     "C", conn_hash_hex,
1307                     "L", shorthost,
1308                     "d", pw->pw_dir,
1309                     "h", host,
1310                     "l", thishost,
1311                     "n", host_arg,
1312                     "p", portstr,
1313                     "r", options.user,
1314                     "u", pw->pw_name,
1315                     (char *)NULL);
1316                 debug3("expanded RemoteCommand: %s", options.remote_command);
1317                 free(cp);
1318                 buffer_append(&command, options.remote_command,
1319                     strlen(options.remote_command));
1320         }
1321
1322         if (options.control_path != NULL) {
1323                 cp = tilde_expand_filename(options.control_path,
1324                     original_real_uid);
1325                 free(options.control_path);
1326                 options.control_path = percent_expand(cp,
1327                     "C", conn_hash_hex,
1328                     "L", shorthost,
1329                     "h", host,
1330                     "l", thishost,
1331                     "n", host_arg,
1332                     "p", portstr,
1333                     "r", options.user,
1334                     "u", pw->pw_name,
1335                     "i", uidstr,
1336                     (char *)NULL);
1337                 free(cp);
1338         }
1339         free(conn_hash_hex);
1340
1341         if (config_test) {
1342                 dump_client_config(&options, host);
1343                 exit(0);
1344         }
1345
1346         if (muxclient_command != 0 && options.control_path == NULL)
1347                 fatal("No ControlPath specified for \"-O\" command");
1348         if (options.control_path != NULL) {
1349                 int sock;
1350                 if ((sock = muxclient(options.control_path)) >= 0) {
1351                         ssh_packet_set_connection(ssh, sock, sock);
1352                         packet_set_mux();
1353                         goto skip_connect;
1354                 }
1355         }
1356
1357         /*
1358          * If hostname canonicalisation was not enabled, then we may not
1359          * have yet resolved the hostname. Do so now.
1360          */
1361         if (addrs == NULL && options.proxy_command == NULL) {
1362                 debug2("resolving \"%s\" port %d", host, options.port);
1363                 if ((addrs = resolve_host(host, options.port, 1,
1364                     cname, sizeof(cname))) == NULL)
1365                         cleanup_exit(255); /* resolve_host logs the error */
1366         }
1367
1368         timeout_ms = options.connection_timeout * 1000;
1369
1370         /* Open a connection to the remote host. */
1371         if (ssh_connect(ssh, host, addrs, &hostaddr, options.port,
1372             options.address_family, options.connection_attempts,
1373             &timeout_ms, options.tcp_keep_alive,
1374             options.use_privileged_port) != 0)
1375                 exit(255);
1376
1377         if (addrs != NULL)
1378                 freeaddrinfo(addrs);
1379
1380         packet_set_timeout(options.server_alive_interval,
1381             options.server_alive_count_max);
1382
1383         ssh = active_state; /* XXX */
1384
1385         if (timeout_ms > 0)
1386                 debug3("timeout: %d ms remain after connect", timeout_ms);
1387
1388         /*
1389          * If we successfully made the connection, load the host private key
1390          * in case we will need it later for combined rsa-rhosts
1391          * authentication. This must be done before releasing extra
1392          * privileges, because the file is only readable by root.
1393          * If we cannot access the private keys, load the public keys
1394          * instead and try to execute the ssh-keysign helper instead.
1395          */
1396         sensitive_data.nkeys = 0;
1397         sensitive_data.keys = NULL;
1398         sensitive_data.external_keysign = 0;
1399         if (options.hostbased_authentication) {
1400                 sensitive_data.nkeys = 11;
1401                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1402                     sizeof(struct sshkey));     /* XXX */
1403                 for (i = 0; i < sensitive_data.nkeys; i++)
1404                         sensitive_data.keys[i] = NULL;
1405
1406                 PRIV_START;
1407 #ifdef OPENSSL_HAS_ECC
1408                 sensitive_data.keys[1] = key_load_private_cert(KEY_ECDSA,
1409                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
1410 #endif
1411                 sensitive_data.keys[2] = key_load_private_cert(KEY_ED25519,
1412                     _PATH_HOST_ED25519_KEY_FILE, "", NULL);
1413                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
1414                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
1415                 sensitive_data.keys[4] = key_load_private_cert(KEY_DSA,
1416                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
1417 #ifdef OPENSSL_HAS_ECC
1418                 sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
1419                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
1420 #endif
1421                 sensitive_data.keys[6] = key_load_private_type(KEY_ED25519,
1422                     _PATH_HOST_ED25519_KEY_FILE, "", NULL, NULL);
1423                 sensitive_data.keys[7] = key_load_private_type(KEY_RSA,
1424                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
1425                 sensitive_data.keys[8] = key_load_private_type(KEY_DSA,
1426                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
1427                 sensitive_data.keys[9] = key_load_private_cert(KEY_XMSS,
1428                     _PATH_HOST_XMSS_KEY_FILE, "", NULL);
1429                 sensitive_data.keys[10] = key_load_private_type(KEY_XMSS,
1430                     _PATH_HOST_XMSS_KEY_FILE, "", NULL, NULL);
1431                 PRIV_END;
1432
1433                 if (options.hostbased_authentication == 1 &&
1434                     sensitive_data.keys[0] == NULL &&
1435                     sensitive_data.keys[5] == NULL &&
1436                     sensitive_data.keys[6] == NULL &&
1437                     sensitive_data.keys[7] == NULL &&
1438                     sensitive_data.keys[8] == NULL &&
1439                     sensitive_data.keys[9] == NULL) {
1440 #ifdef OPENSSL_HAS_ECC
1441                         sensitive_data.keys[1] = key_load_cert(
1442                             _PATH_HOST_ECDSA_KEY_FILE);
1443 #endif
1444                         sensitive_data.keys[2] = key_load_cert(
1445                             _PATH_HOST_ED25519_KEY_FILE);
1446                         sensitive_data.keys[3] = key_load_cert(
1447                             _PATH_HOST_RSA_KEY_FILE);
1448                         sensitive_data.keys[4] = key_load_cert(
1449                             _PATH_HOST_DSA_KEY_FILE);
1450 #ifdef OPENSSL_HAS_ECC
1451                         sensitive_data.keys[5] = key_load_public(
1452                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
1453 #endif
1454                         sensitive_data.keys[6] = key_load_public(
1455                             _PATH_HOST_ED25519_KEY_FILE, NULL);
1456                         sensitive_data.keys[7] = key_load_public(
1457                             _PATH_HOST_RSA_KEY_FILE, NULL);
1458                         sensitive_data.keys[8] = key_load_public(
1459                             _PATH_HOST_DSA_KEY_FILE, NULL);
1460                         sensitive_data.keys[9] = key_load_cert(
1461                             _PATH_HOST_XMSS_KEY_FILE);
1462                         sensitive_data.keys[10] = key_load_public(
1463                             _PATH_HOST_XMSS_KEY_FILE, NULL);
1464                         sensitive_data.external_keysign = 1;
1465                 }
1466         }
1467         /*
1468          * Get rid of any extra privileges that we may have.  We will no
1469          * longer need them.  Also, extra privileges could make it very hard
1470          * to read identity files and other non-world-readable files from the
1471          * user's home directory if it happens to be on a NFS volume where
1472          * root is mapped to nobody.
1473          */
1474         if (original_effective_uid == 0) {
1475                 PRIV_START;
1476                 permanently_set_uid(pw);
1477         }
1478
1479         /*
1480          * Now that we are back to our own permissions, create ~/.ssh
1481          * directory if it doesn't already exist.
1482          */
1483         if (config == NULL) {
1484                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1485                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1486                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
1487 #ifdef WITH_SELINUX
1488                         ssh_selinux_setfscreatecon(buf);
1489 #endif
1490                         if (mkdir(buf, 0700) < 0)
1491                                 error("Could not create directory '%.200s'.",
1492                                     buf);
1493 #ifdef WITH_SELINUX
1494                         ssh_selinux_setfscreatecon(NULL);
1495 #endif
1496                 }
1497         }
1498         /* load options.identity_files */
1499         load_public_identity_files(pw);
1500
1501         /* optionally set the SSH_AUTHSOCKET_ENV_NAME varibale */
1502         if (options.identity_agent &&
1503             strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
1504                 if (strcmp(options.identity_agent, "none") == 0) {
1505                         unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1506                 } else {
1507                         p = tilde_expand_filename(options.identity_agent,
1508                             original_real_uid);
1509                         cp = percent_expand(p, "d", pw->pw_dir,
1510                             "u", pw->pw_name, "l", thishost, "h", host,
1511                             "r", options.user, (char *)NULL);
1512                         setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
1513                         free(cp);
1514                         free(p);
1515                 }
1516         }
1517
1518         /* Expand ~ in known host file names. */
1519         tilde_expand_paths(options.system_hostfiles,
1520             options.num_system_hostfiles);
1521         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1522
1523         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1524         signal(SIGCHLD, main_sigchld_handler);
1525
1526         /* Log into the remote system.  Never returns if the login fails. */
1527         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1528             options.port, pw, timeout_ms);
1529
1530         if (packet_connection_is_on_socket()) {
1531                 verbose("Authenticated to %s ([%s]:%d).", host,
1532                     ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1533         } else {
1534                 verbose("Authenticated to %s (via proxy).", host);
1535         }
1536
1537         /* We no longer need the private host keys.  Clear them now. */
1538         if (sensitive_data.nkeys != 0) {
1539                 for (i = 0; i < sensitive_data.nkeys; i++) {
1540                         if (sensitive_data.keys[i] != NULL) {
1541                                 /* Destroys contents safely */
1542                                 debug3("clear hostkey %d", i);
1543                                 key_free(sensitive_data.keys[i]);
1544                                 sensitive_data.keys[i] = NULL;
1545                         }
1546                 }
1547                 free(sensitive_data.keys);
1548         }
1549         for (i = 0; i < options.num_identity_files; i++) {
1550                 free(options.identity_files[i]);
1551                 options.identity_files[i] = NULL;
1552                 if (options.identity_keys[i]) {
1553                         key_free(options.identity_keys[i]);
1554                         options.identity_keys[i] = NULL;
1555                 }
1556         }
1557         for (i = 0; i < options.num_certificate_files; i++) {
1558                 free(options.certificate_files[i]);
1559                 options.certificate_files[i] = NULL;
1560         }
1561
1562  skip_connect:
1563         exit_status = ssh_session2(ssh, pw);
1564         packet_close();
1565
1566         if (options.control_path != NULL && muxserver_sock != -1)
1567                 unlink(options.control_path);
1568
1569         /* Kill ProxyCommand if it is running. */
1570         ssh_kill_proxy_command();
1571
1572         return exit_status;
1573 }
1574
1575 static void
1576 control_persist_detach(void)
1577 {
1578         pid_t pid;
1579         int devnull, keep_stderr;
1580
1581         debug("%s: backgrounding master process", __func__);
1582
1583         /*
1584          * master (current process) into the background, and make the
1585          * foreground process a client of the backgrounded master.
1586          */
1587         switch ((pid = fork())) {
1588         case -1:
1589                 fatal("%s: fork: %s", __func__, strerror(errno));
1590         case 0:
1591                 /* Child: master process continues mainloop */
1592                 break;
1593         default:
1594                 /* Parent: set up mux slave to connect to backgrounded master */
1595                 debug2("%s: background process is %ld", __func__, (long)pid);
1596                 stdin_null_flag = ostdin_null_flag;
1597                 options.request_tty = orequest_tty;
1598                 tty_flag = otty_flag;
1599                 close(muxserver_sock);
1600                 muxserver_sock = -1;
1601                 options.control_master = SSHCTL_MASTER_NO;
1602                 muxclient(options.control_path);
1603                 /* muxclient() doesn't return on success. */
1604                 fatal("Failed to connect to new control master");
1605         }
1606         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1607                 error("%s: open(\"/dev/null\"): %s", __func__,
1608                     strerror(errno));
1609         } else {
1610                 keep_stderr = log_is_on_stderr() && debug_flag;
1611                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1612                     dup2(devnull, STDOUT_FILENO) == -1 ||
1613                     (!keep_stderr && dup2(devnull, STDERR_FILENO) == -1))
1614                         error("%s: dup2: %s", __func__, strerror(errno));
1615                 if (devnull > STDERR_FILENO)
1616                         close(devnull);
1617         }
1618         daemon(1, 1);
1619         setproctitle("%s [mux]", options.control_path);
1620 }
1621
1622 /* Do fork() after authentication. Used by "ssh -f" */
1623 static void
1624 fork_postauth(void)
1625 {
1626         if (need_controlpersist_detach)
1627                 control_persist_detach();
1628         debug("forking to background");
1629         fork_after_authentication_flag = 0;
1630         if (daemon(1, 1) < 0)
1631                 fatal("daemon() failed: %.200s", strerror(errno));
1632 }
1633
1634 /* Callback for remote forward global requests */
1635 static void
1636 ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
1637 {
1638         struct Forward *rfwd = (struct Forward *)ctxt;
1639
1640         /* XXX verbose() on failure? */
1641         debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1642             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1643             rfwd->listen_path ? rfwd->listen_path :
1644             rfwd->listen_host ? rfwd->listen_host : "",
1645             (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1646             rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1647             rfwd->connect_host, rfwd->connect_port);
1648         if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1649                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1650                         rfwd->allocated_port = packet_get_int();
1651                         logit("Allocated port %u for remote forward to %s:%d",
1652                             rfwd->allocated_port,
1653                             rfwd->connect_host, rfwd->connect_port);
1654                         channel_update_permitted_opens(ssh,
1655                             rfwd->handle, rfwd->allocated_port);
1656                 } else {
1657                         channel_update_permitted_opens(ssh, rfwd->handle, -1);
1658                 }
1659         }
1660
1661         if (type == SSH2_MSG_REQUEST_FAILURE) {
1662                 if (options.exit_on_forward_failure) {
1663                         if (rfwd->listen_path != NULL)
1664                                 fatal("Error: remote port forwarding failed "
1665                                     "for listen path %s", rfwd->listen_path);
1666                         else
1667                                 fatal("Error: remote port forwarding failed "
1668                                     "for listen port %d", rfwd->listen_port);
1669                 } else {
1670                         if (rfwd->listen_path != NULL)
1671                                 logit("Warning: remote port forwarding failed "
1672                                     "for listen path %s", rfwd->listen_path);
1673                         else
1674                                 logit("Warning: remote port forwarding failed "
1675                                     "for listen port %d", rfwd->listen_port);
1676                 }
1677         }
1678         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1679                 debug("All remote forwarding requests processed");
1680                 if (fork_after_authentication_flag)
1681                         fork_postauth();
1682         }
1683 }
1684
1685 static void
1686 client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
1687 {
1688         debug("stdio forwarding: done");
1689         cleanup_exit(0);
1690 }
1691
1692 static void
1693 ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1694 {
1695         if (!success)
1696                 fatal("stdio forwarding failed");
1697 }
1698
1699 static void
1700 ssh_init_stdio_forwarding(struct ssh *ssh)
1701 {
1702         Channel *c;
1703         int in, out;
1704
1705         if (options.stdio_forward_host == NULL)
1706                 return;
1707
1708         debug3("%s: %s:%d", __func__, options.stdio_forward_host,
1709             options.stdio_forward_port);
1710
1711         if ((in = dup(STDIN_FILENO)) < 0 ||
1712             (out = dup(STDOUT_FILENO)) < 0)
1713                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1714         if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
1715             options.stdio_forward_port, in, out)) == NULL)
1716                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1717         channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
1718         channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
1719 }
1720
1721 static void
1722 ssh_init_forwarding(struct ssh *ssh, char **ifname)
1723 {
1724         int success = 0;
1725         int i;
1726
1727         /* Initiate local TCP/IP port forwardings. */
1728         for (i = 0; i < options.num_local_forwards; i++) {
1729                 debug("Local connections to %.200s:%d forwarded to remote "
1730                     "address %.200s:%d",
1731                     (options.local_forwards[i].listen_path != NULL) ?
1732                     options.local_forwards[i].listen_path :
1733                     (options.local_forwards[i].listen_host == NULL) ?
1734                     (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1735                     options.local_forwards[i].listen_host,
1736                     options.local_forwards[i].listen_port,
1737                     (options.local_forwards[i].connect_path != NULL) ?
1738                     options.local_forwards[i].connect_path :
1739                     options.local_forwards[i].connect_host,
1740                     options.local_forwards[i].connect_port);
1741                 success += channel_setup_local_fwd_listener(ssh,
1742                     &options.local_forwards[i], &options.fwd_opts);
1743         }
1744         if (i > 0 && success != i && options.exit_on_forward_failure)
1745                 fatal("Could not request local forwarding.");
1746         if (i > 0 && success == 0)
1747                 error("Could not request local forwarding.");
1748
1749         /* Initiate remote TCP/IP port forwardings. */
1750         for (i = 0; i < options.num_remote_forwards; i++) {
1751                 debug("Remote connections from %.200s:%d forwarded to "
1752                     "local address %.200s:%d",
1753                     (options.remote_forwards[i].listen_path != NULL) ?
1754                     options.remote_forwards[i].listen_path :
1755                     (options.remote_forwards[i].listen_host == NULL) ?
1756                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1757                     options.remote_forwards[i].listen_port,
1758                     (options.remote_forwards[i].connect_path != NULL) ?
1759                     options.remote_forwards[i].connect_path :
1760                     options.remote_forwards[i].connect_host,
1761                     options.remote_forwards[i].connect_port);
1762                 options.remote_forwards[i].handle =
1763                     channel_request_remote_forwarding(ssh,
1764                     &options.remote_forwards[i]);
1765                 if (options.remote_forwards[i].handle < 0) {
1766                         if (options.exit_on_forward_failure)
1767                                 fatal("Could not request remote forwarding.");
1768                         else
1769                                 logit("Warning: Could not request remote "
1770                                     "forwarding.");
1771                 } else {
1772                         client_register_global_confirm(
1773                             ssh_confirm_remote_forward,
1774                             &options.remote_forwards[i]);
1775                 }
1776         }
1777
1778         /* Initiate tunnel forwarding. */
1779         if (options.tun_open != SSH_TUNMODE_NO) {
1780                 if ((*ifname = client_request_tun_fwd(ssh,
1781                     options.tun_open, options.tun_local,
1782                     options.tun_remote)) == NULL) {
1783                         if (options.exit_on_forward_failure)
1784                                 fatal("Could not request tunnel forwarding.");
1785                         else
1786                                 error("Could not request tunnel forwarding.");
1787                 }
1788         }
1789 }
1790
1791 static void
1792 check_agent_present(void)
1793 {
1794         int r;
1795
1796         if (options.forward_agent) {
1797                 /* Clear agent forwarding if we don't have an agent. */
1798                 if ((r = ssh_get_authentication_socket(NULL)) != 0) {
1799                         options.forward_agent = 0;
1800                         if (r != SSH_ERR_AGENT_NOT_PRESENT)
1801                                 debug("ssh_get_authentication_socket: %s",
1802                                     ssh_err(r));
1803                 }
1804         }
1805 }
1806
1807 static void
1808 ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
1809 {
1810         extern char **environ;
1811         const char *display;
1812         int interactive = tty_flag;
1813         char *proto = NULL, *data = NULL;
1814
1815         if (!success)
1816                 return; /* No need for error message, channels code sens one */
1817
1818         display = getenv("DISPLAY");
1819         if (display == NULL && options.forward_x11)
1820                 debug("X11 forwarding requested but DISPLAY not set");
1821         if (options.forward_x11 && client_x11_get_proto(ssh, display,
1822             options.xauth_location, options.forward_x11_trusted,
1823             options.forward_x11_timeout, &proto, &data) == 0) {
1824                 /* Request forwarding with authentication spoofing. */
1825                 debug("Requesting X11 forwarding with authentication "
1826                     "spoofing.");
1827                 x11_request_forwarding_with_spoofing(ssh, id, display, proto,
1828                     data, 1);
1829                 client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
1830                 /* XXX exit_on_forward_failure */
1831                 interactive = 1;
1832         }
1833
1834         check_agent_present();
1835         if (options.forward_agent) {
1836                 debug("Requesting authentication agent forwarding.");
1837                 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1838                 packet_send();
1839         }
1840
1841         /* Tell the packet module whether this is an interactive session. */
1842         packet_set_interactive(interactive,
1843             options.ip_qos_interactive, options.ip_qos_bulk);
1844
1845         client_session2_setup(ssh, id, tty_flag, subsystem_flag, getenv("TERM"),
1846             NULL, fileno(stdin), &command, environ);
1847 }
1848
1849 /* open new channel for a session */
1850 static int
1851 ssh_session2_open(struct ssh *ssh)
1852 {
1853         Channel *c;
1854         int window, packetmax, in, out, err;
1855
1856         if (stdin_null_flag) {
1857                 in = open(_PATH_DEVNULL, O_RDONLY);
1858         } else {
1859                 in = dup(STDIN_FILENO);
1860         }
1861         out = dup(STDOUT_FILENO);
1862         err = dup(STDERR_FILENO);
1863
1864         if (in < 0 || out < 0 || err < 0)
1865                 fatal("dup() in/out/err failed");
1866
1867         /* enable nonblocking unless tty */
1868         if (!isatty(in))
1869                 set_nonblock(in);
1870         if (!isatty(out))
1871                 set_nonblock(out);
1872         if (!isatty(err))
1873                 set_nonblock(err);
1874
1875         window = CHAN_SES_WINDOW_DEFAULT;
1876         packetmax = CHAN_SES_PACKET_DEFAULT;
1877         if (tty_flag) {
1878                 window >>= 1;
1879                 packetmax >>= 1;
1880         }
1881         c = channel_new(ssh,
1882             "session", SSH_CHANNEL_OPENING, in, out, err,
1883             window, packetmax, CHAN_EXTENDED_WRITE,
1884             "client-session", /*nonblock*/0);
1885
1886         debug3("%s: channel_new: %d", __func__, c->self);
1887
1888         channel_send_open(ssh, c->self);
1889         if (!no_shell_flag)
1890                 channel_register_open_confirm(ssh, c->self,
1891                     ssh_session2_setup, NULL);
1892
1893         return c->self;
1894 }
1895
1896 static int
1897 ssh_session2(struct ssh *ssh, struct passwd *pw)
1898 {
1899         int devnull, id = -1;
1900         char *cp, *tun_fwd_ifname = NULL;
1901
1902         /* XXX should be pre-session */
1903         if (!options.control_persist)
1904                 ssh_init_stdio_forwarding(ssh);
1905
1906         ssh_init_forwarding(ssh, &tun_fwd_ifname);
1907
1908         if (options.local_command != NULL) {
1909                 debug3("expanding LocalCommand: %s", options.local_command);
1910                 cp = options.local_command;
1911                 options.local_command = percent_expand(cp,
1912                     "C", conn_hash_hex,
1913                     "L", shorthost,
1914                     "d", pw->pw_dir,
1915                     "h", host,
1916                     "l", thishost,
1917                     "n", host_arg,
1918                     "p", portstr,
1919                     "r", options.user,
1920                     "u", pw->pw_name,
1921                     "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
1922                     (char *)NULL);
1923                 debug3("expanded LocalCommand: %s", options.local_command);
1924                 free(cp);
1925         }
1926
1927         /* Start listening for multiplex clients */
1928         if (!packet_get_mux())
1929                 muxserver_listen(ssh);
1930
1931         /*
1932          * If we are in control persist mode and have a working mux listen
1933          * socket, then prepare to background ourselves and have a foreground
1934          * client attach as a control slave.
1935          * NB. we must save copies of the flags that we override for
1936          * the backgrounding, since we defer attachment of the slave until
1937          * after the connection is fully established (in particular,
1938          * async rfwd replies have been received for ExitOnForwardFailure).
1939          */
1940         if (options.control_persist && muxserver_sock != -1) {
1941                 ostdin_null_flag = stdin_null_flag;
1942                 ono_shell_flag = no_shell_flag;
1943                 orequest_tty = options.request_tty;
1944                 otty_flag = tty_flag;
1945                 stdin_null_flag = 1;
1946                 no_shell_flag = 1;
1947                 tty_flag = 0;
1948                 if (!fork_after_authentication_flag)
1949                         need_controlpersist_detach = 1;
1950                 fork_after_authentication_flag = 1;
1951         }
1952         /*
1953          * ControlPersist mux listen socket setup failed, attempt the
1954          * stdio forward setup that we skipped earlier.
1955          */
1956         if (options.control_persist && muxserver_sock == -1)
1957                 ssh_init_stdio_forwarding(ssh);
1958
1959         if (!no_shell_flag)
1960                 id = ssh_session2_open(ssh);
1961         else {
1962                 packet_set_interactive(
1963                     options.control_master == SSHCTL_MASTER_NO,
1964                     options.ip_qos_interactive, options.ip_qos_bulk);
1965         }
1966
1967         /* If we don't expect to open a new session, then disallow it */
1968         if (options.control_master == SSHCTL_MASTER_NO &&
1969             (datafellows & SSH_NEW_OPENSSH)) {
1970                 debug("Requesting no-more-sessions@openssh.com");
1971                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1972                 packet_put_cstring("no-more-sessions@openssh.com");
1973                 packet_put_char(0);
1974                 packet_send();
1975         }
1976
1977         /* Execute a local command */
1978         if (options.local_command != NULL &&
1979             options.permit_local_command)
1980                 ssh_local_cmd(options.local_command);
1981
1982         /*
1983          * stdout is now owned by the session channel; clobber it here
1984          * so future channel closes are propagated to the local fd.
1985          * NB. this can only happen after LocalCommand has completed,
1986          * as it may want to write to stdout.
1987          */
1988         if (!need_controlpersist_detach) {
1989                 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
1990                         error("%s: open %s: %s", __func__,
1991                             _PATH_DEVNULL, strerror(errno));
1992                 if (dup2(devnull, STDOUT_FILENO) < 0)
1993                         fatal("%s: dup2() stdout failed", __func__);
1994                 if (devnull > STDERR_FILENO)
1995                         close(devnull);
1996         }
1997
1998         /*
1999          * If requested and we are not interested in replies to remote
2000          * forwarding requests, then let ssh continue in the background.
2001          */
2002         if (fork_after_authentication_flag) {
2003                 if (options.exit_on_forward_failure &&
2004                     options.num_remote_forwards > 0) {
2005                         debug("deferring postauth fork until remote forward "
2006                             "confirmation received");
2007                 } else
2008                         fork_postauth();
2009         }
2010
2011         return client_loop(ssh, tty_flag, tty_flag ?
2012             options.escape_char : SSH_ESCAPECHAR_NONE, id);
2013 }
2014
2015 /* Loads all IdentityFile and CertificateFile keys */
2016 static void
2017 load_public_identity_files(struct passwd *pw)
2018 {
2019         char *filename, *cp;
2020         struct sshkey *public;
2021         int i;
2022         u_int n_ids, n_certs;
2023         char *identity_files[SSH_MAX_IDENTITY_FILES];
2024         struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
2025         char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
2026         struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
2027 #ifdef ENABLE_PKCS11
2028         struct sshkey **keys;
2029         int nkeys;
2030 #endif /* PKCS11 */
2031
2032         n_ids = n_certs = 0;
2033         memset(identity_files, 0, sizeof(identity_files));
2034         memset(identity_keys, 0, sizeof(identity_keys));
2035         memset(certificate_files, 0, sizeof(certificate_files));
2036         memset(certificates, 0, sizeof(certificates));
2037
2038 #ifdef ENABLE_PKCS11
2039         if (options.pkcs11_provider != NULL &&
2040             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
2041             (pkcs11_init(!options.batch_mode) == 0) &&
2042             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
2043             &keys)) > 0) {
2044                 for (i = 0; i < nkeys; i++) {
2045                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
2046                                 key_free(keys[i]);
2047                                 continue;
2048                         }
2049                         identity_keys[n_ids] = keys[i];
2050                         identity_files[n_ids] =
2051                             xstrdup(options.pkcs11_provider); /* XXX */
2052                         n_ids++;
2053                 }
2054                 free(keys);
2055         }
2056 #endif /* ENABLE_PKCS11 */
2057         if ((pw = getpwuid(original_real_uid)) == NULL)
2058                 fatal("load_public_identity_files: getpwuid failed");
2059         for (i = 0; i < options.num_identity_files; i++) {
2060                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
2061                     strcasecmp(options.identity_files[i], "none") == 0) {
2062                         free(options.identity_files[i]);
2063                         options.identity_files[i] = NULL;
2064                         continue;
2065                 }
2066                 cp = tilde_expand_filename(options.identity_files[i],
2067                     original_real_uid);
2068                 filename = percent_expand(cp, "d", pw->pw_dir,
2069                     "u", pw->pw_name, "l", thishost, "h", host,
2070                     "r", options.user, (char *)NULL);
2071                 free(cp);
2072                 public = key_load_public(filename, NULL);
2073                 debug("identity file %s type %d", filename,
2074                     public ? public->type : -1);
2075                 free(options.identity_files[i]);
2076                 identity_files[n_ids] = filename;
2077                 identity_keys[n_ids] = public;
2078
2079                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2080                         continue;
2081
2082                 /*
2083                  * If no certificates have been explicitly listed then try
2084                  * to add the default certificate variant too.
2085                  */
2086                 if (options.num_certificate_files != 0)
2087                         continue;
2088                 xasprintf(&cp, "%s-cert", filename);
2089                 public = key_load_public(cp, NULL);
2090                 debug("identity file %s type %d", cp,
2091                     public ? public->type : -1);
2092                 if (public == NULL) {
2093                         free(cp);
2094                         continue;
2095                 }
2096                 if (!key_is_cert(public)) {
2097                         debug("%s: key %s type %s is not a certificate",
2098                             __func__, cp, key_type(public));
2099                         key_free(public);
2100                         free(cp);
2101                         continue;
2102                 }
2103                 /* NB. leave filename pointing to private key */
2104                 identity_files[n_ids] = xstrdup(filename);
2105                 identity_keys[n_ids] = public;
2106                 n_ids++;
2107         }
2108
2109         if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
2110                 fatal("%s: too many certificates", __func__);
2111         for (i = 0; i < options.num_certificate_files; i++) {
2112                 cp = tilde_expand_filename(options.certificate_files[i],
2113                     original_real_uid);
2114                 filename = percent_expand(cp, "d", pw->pw_dir,
2115                     "u", pw->pw_name, "l", thishost, "h", host,
2116                     "r", options.user, (char *)NULL);
2117                 free(cp);
2118
2119                 public = key_load_public(filename, NULL);
2120                 debug("certificate file %s type %d", filename,
2121                     public ? public->type : -1);
2122                 free(options.certificate_files[i]);
2123                 options.certificate_files[i] = NULL;
2124                 if (public == NULL) {
2125                         free(filename);
2126                         continue;
2127                 }
2128                 if (!key_is_cert(public)) {
2129                         debug("%s: key %s type %s is not a certificate",
2130                             __func__, filename, key_type(public));
2131                         key_free(public);
2132                         free(filename);
2133                         continue;
2134                 }
2135                 certificate_files[n_certs] = filename;
2136                 certificates[n_certs] = public;
2137                 ++n_certs;
2138         }
2139
2140         options.num_identity_files = n_ids;
2141         memcpy(options.identity_files, identity_files, sizeof(identity_files));
2142         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2143
2144         options.num_certificate_files = n_certs;
2145         memcpy(options.certificate_files,
2146             certificate_files, sizeof(certificate_files));
2147         memcpy(options.certificates, certificates, sizeof(certificates));
2148 }
2149
2150 static void
2151 main_sigchld_handler(int sig)
2152 {
2153         int save_errno = errno;
2154         pid_t pid;
2155         int status;
2156
2157         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2158             (pid < 0 && errno == EINTR))
2159                 ;
2160         errno = save_errno;
2161 }