crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.494 2018/10/03 06:38:35 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44 __RCSID("$FreeBSD$");
  45
  46 #include <sys/types.h>
  47 #ifdef HAVE_SYS_STAT_H
  48 # include <sys/stat.h>
  49 #endif
  50 #include <sys/resource.h>
  51 #include <sys/ioctl.h>
  52 #include <sys/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 "sshbuf.h"
  92 #include "channels.h"
  93 #include "sshkey.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 "version.h"
 109 #include "ssherr.h"
 110 #include "myproposal.h"
 111 #include "utf8.h"
 112
 113 #ifdef ENABLE_PKCS11
 114 #include "ssh-pkcs11.h"
 115 #endif
 116
 117 extern char *__progname;
 118
 119 /* Saves a copy of argv for setproctitle emulation */
 120 #ifndef HAVE_SETPROCTITLE
 121 static char **saved_av;
 122 #endif
 123
 124 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 125 int debug_flag = 0;
 126
 127 /* Flag indicating whether a tty should be requested */
 128 int tty_flag = 0;
 129
 130 /* don't exec a shell */
 131 int no_shell_flag = 0;
 132
 133 /*
 134  * Flag indicating that nothing should be read from stdin.  This can be set
 135  * on the command line.
 136  */
 137 int stdin_null_flag = 0;
 138
 139 /*
 140  * Flag indicating that the current process should be backgrounded and
 141  * a new slave launched in the foreground for ControlPersist.
 142  */
 143 int need_controlpersist_detach = 0;
 144
 145 /* Copies of flags for ControlPersist foreground slave */
 146 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 147
 148 /*
 149  * Flag indicating that ssh should fork after authentication.  This is useful
 150  * so that the passphrase can be entered manually, and then ssh goes to the
 151  * background.
 152  */
 153 int fork_after_authentication_flag = 0;
 154
 155 /*
 156  * General data structure for command line options and options configurable
 157  * in configuration files.  See readconf.h.
 158  */
 159 Options options;
 160
 161 /* optional user configfile */
 162 char *config = NULL;
 163
 164 /*
 165  * Name of the host we are connecting to.  This is the name given on the
 166  * command line, or the HostName specified for the user-supplied name in a
 167  * configuration file.
 168  */
 169 char *host;
 170
 171 /* Various strings used to to percent_expand() arguments */
 172 static char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 173 static char uidstr[32], *host_arg, *conn_hash_hex;
 174
 175 /* socket address the host resolves to */
 176 struct sockaddr_storage hostaddr;
 177
 178 /* Private host keys. */
 179 Sensitive sensitive_data;
 180
 181 /* command to be executed */
 182 struct sshbuf *command;
 183
 184 /* Should we execute a command or invoke a subsystem? */
 185 int subsystem_flag = 0;
 186
 187 /* # of replies received for global requests */
 188 static int remote_forward_confirms_received = 0;
 189
 190 /* mux.c */
 191 extern int muxserver_sock;
 192 extern u_int muxclient_command;
 193
 194 /* Prints a help message to the user.  This function never returns. */
 195
 196 static void
 197 usage(void)
 198 {
 199         fprintf(stderr,
 200 "usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
 201 "           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
 202 "           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
 203 "           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
 204 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
 205 "           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
 206 "           [-w local_tun[:remote_tun]] destination [command]\n"
 207         );
 208         exit(255);
 209 }
 210
 211 static int ssh_session2(struct ssh *, struct passwd *);
 212 static void load_public_identity_files(struct passwd *);
 213 static void main_sigchld_handler(int);
 214
 215 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 216 static void
 217 tilde_expand_paths(char **paths, u_int num_paths)
 218 {
 219         u_int i;
 220         char *cp;
 221
 222         for (i = 0; i < num_paths; i++) {
 223                 cp = tilde_expand_filename(paths[i], getuid());
 224                 free(paths[i]);
 225                 paths[i] = cp;
 226         }
 227 }
 228
 229 /*
 230  * Attempt to resolve a host name / port to a set of addresses and
 231  * optionally return any CNAMEs encountered along the way.
 232  * Returns NULL on failure.
 233  * NB. this function must operate with a options having undefined members.
 234  */
 235 static struct addrinfo *
 236 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 237 {
 238         char strport[NI_MAXSERV];
 239         struct addrinfo hints, *res;
 240         int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
 241
 242         if (port <= 0)
 243                 port = default_ssh_port();
 244
 245         snprintf(strport, sizeof strport, "%d", port);
 246         memset(&hints, 0, sizeof(hints));
 247         hints.ai_family = options.address_family == -1 ?
 248             AF_UNSPEC : options.address_family;
 249         hints.ai_socktype = SOCK_STREAM;
 250         if (cname != NULL)
 251                 hints.ai_flags = AI_CANONNAME;
 252         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 253                 if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
 254                         loglevel = SYSLOG_LEVEL_ERROR;
 255                 do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
 256                     __progname, name, ssh_gai_strerror(gaierr));
 257                 return NULL;
 258         }
 259         if (cname != NULL && res->ai_canonname != NULL) {
 260                 if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
 261                         error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
 262                             __func__, name,  res->ai_canonname, (u_long)clen);
 263                         if (clen > 0)
 264                                 *cname = '\0';
 265                 }
 266         }
 267         return res;
 268 }
 269
 270 /* Returns non-zero if name can only be an address and not a hostname */
 271 static int
 272 is_addr_fast(const char *name)
 273 {
 274         return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
 275             strspn(name, "0123456789.") == strlen(name));
 276 }
 277
 278 /* Returns non-zero if name represents a valid, single address */
 279 static int
 280 is_addr(const char *name)
 281 {
 282         char strport[NI_MAXSERV];
 283         struct addrinfo hints, *res;
 284
 285         if (is_addr_fast(name))
 286                 return 1;
 287
 288         snprintf(strport, sizeof strport, "%u", default_ssh_port());
 289         memset(&hints, 0, sizeof(hints));
 290         hints.ai_family = options.address_family == -1 ?
 291             AF_UNSPEC : options.address_family;
 292         hints.ai_socktype = SOCK_STREAM;
 293         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
 294         if (getaddrinfo(name, strport, &hints, &res) != 0)
 295                 return 0;
 296         if (res == NULL || res->ai_next != NULL) {
 297                 freeaddrinfo(res);
 298                 return 0;
 299         }
 300         freeaddrinfo(res);
 301         return 1;
 302 }
 303
 304 /*
 305  * Attempt to resolve a numeric host address / port to a single address.
 306  * Returns a canonical address string.
 307  * Returns NULL on failure.
 308  * NB. this function must operate with a options having undefined members.
 309  */
 310 static struct addrinfo *
 311 resolve_addr(const char *name, int port, char *caddr, size_t clen)
 312 {
 313         char addr[NI_MAXHOST], strport[NI_MAXSERV];
 314         struct addrinfo hints, *res;
 315         int gaierr;
 316
 317         if (port <= 0)
 318                 port = default_ssh_port();
 319         snprintf(strport, sizeof strport, "%u", port);
 320         memset(&hints, 0, sizeof(hints));
 321         hints.ai_family = options.address_family == -1 ?
 322             AF_UNSPEC : options.address_family;
 323         hints.ai_socktype = SOCK_STREAM;
 324         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
 325         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 326                 debug2("%s: could not resolve name %.100s as address: %s",
 327                     __func__, name, ssh_gai_strerror(gaierr));
 328                 return NULL;
 329         }
 330         if (res == NULL) {
 331                 debug("%s: getaddrinfo %.100s returned no addresses",
 332                  __func__, name);
 333                 return NULL;
 334         }
 335         if (res->ai_next != NULL) {
 336                 debug("%s: getaddrinfo %.100s returned multiple addresses",
 337                     __func__, name);
 338                 goto fail;
 339         }
 340         if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
 341             addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
 342                 debug("%s: Could not format address for name %.100s: %s",
 343                     __func__, name, ssh_gai_strerror(gaierr));
 344                 goto fail;
 345         }
 346         if (strlcpy(caddr, addr, clen) >= clen) {
 347                 error("%s: host \"%s\" addr \"%s\" too long (max %lu)",
 348                     __func__, name,  addr, (u_long)clen);
 349                 if (clen > 0)
 350                         *caddr = '\0';
 351  fail:
 352                 freeaddrinfo(res);
 353                 return NULL;
 354         }
 355         return res;
 356 }
 357
 358 /*
 359  * Check whether the cname is a permitted replacement for the hostname
 360  * and perform the replacement if it is.
 361  * NB. this function must operate with a options having undefined members.
 362  */
 363 static int
 364 check_follow_cname(int direct, char **namep, const char *cname)
 365 {
 366         int i;
 367         struct allowed_cname *rule;
 368
 369         if (*cname == '\0' || options.num_permitted_cnames == 0 ||
 370             strcmp(*namep, cname) == 0)
 371                 return 0;
 372         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 373                 return 0;
 374         /*
 375          * Don't attempt to canonicalize names that will be interpreted by
 376          * a proxy or jump host unless the user specifically requests so.
 377          */
 378         if (!direct &&
 379             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 380                 return 0;
 381         debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
 382         for (i = 0; i < options.num_permitted_cnames; i++) {
 383                 rule = options.permitted_cnames + i;
 384                 if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
 385                     match_pattern_list(cname, rule->target_list, 1) != 1)
 386                         continue;
 387                 verbose("Canonicalized DNS aliased hostname "
 388                     "\"%s\" => \"%s\"", *namep, cname);
 389                 free(*namep);
 390                 *namep = xstrdup(cname);
 391                 return 1;
 392         }
 393         return 0;
 394 }
 395
 396 /*
 397  * Attempt to resolve the supplied hostname after applying the user's
 398  * canonicalization rules. Returns the address list for the host or NULL
 399  * if no name was found after canonicalization.
 400  * NB. this function must operate with a options having undefined members.
 401  */
 402 static struct addrinfo *
 403 resolve_canonicalize(char **hostp, int port)
 404 {
 405         int i, direct, ndots;
 406         char *cp, *fullhost, newname[NI_MAXHOST];
 407         struct addrinfo *addrs;
 408
 409         /*
 410          * Attempt to canonicalise addresses, regardless of
 411          * whether hostname canonicalisation was requested
 412          */
 413         if ((addrs = resolve_addr(*hostp, port,
 414             newname, sizeof(newname))) != NULL) {
 415                 debug2("%s: hostname %.100s is address", __func__, *hostp);
 416                 if (strcasecmp(*hostp, newname) != 0) {
 417                         debug2("%s: canonicalised address \"%s\" => \"%s\"",
 418                             __func__, *hostp, newname);
 419                         free(*hostp);
 420                         *hostp = xstrdup(newname);
 421                 }
 422                 return addrs;
 423         }
 424
 425         /*
 426          * If this looks like an address but didn't parse as one, it might
 427          * be an address with an invalid interface scope. Skip further
 428          * attempts at canonicalisation.
 429          */
 430         if (is_addr_fast(*hostp)) {
 431                 debug("%s: hostname %.100s is an unrecognised address",
 432                     __func__, *hostp);
 433                 return NULL;
 434         }
 435
 436         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 437                 return NULL;
 438
 439         /*
 440          * Don't attempt to canonicalize names that will be interpreted by
 441          * a proxy unless the user specifically requests so.
 442          */
 443         direct = option_clear_or_none(options.proxy_command) &&
 444             options.jump_host == NULL;
 445         if (!direct &&
 446             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 447                 return NULL;
 448
 449         /* If domain name is anchored, then resolve it now */
 450         if ((*hostp)[strlen(*hostp) - 1] == '.') {
 451                 debug3("%s: name is fully qualified", __func__);
 452                 fullhost = xstrdup(*hostp);
 453                 if ((addrs = resolve_host(fullhost, port, 0,
 454                     newname, sizeof(newname))) != NULL)
 455                         goto found;
 456                 free(fullhost);
 457                 goto notfound;
 458         }
 459
 460         /* Don't apply canonicalization to sufficiently-qualified hostnames */
 461         ndots = 0;
 462         for (cp = *hostp; *cp != '\0'; cp++) {
 463                 if (*cp == '.')
 464                         ndots++;
 465         }
 466         if (ndots > options.canonicalize_max_dots) {
 467                 debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
 468                     __func__, *hostp, options.canonicalize_max_dots);
 469                 return NULL;
 470         }
 471         /* Attempt each supplied suffix */
 472         for (i = 0; i < options.num_canonical_domains; i++) {
 473                 *newname = '\0';
 474                 xasprintf(&fullhost, "%s.%s.", *hostp,
 475                     options.canonical_domains[i]);
 476                 debug3("%s: attempting \"%s\" => \"%s\"", __func__,
 477                     *hostp, fullhost);
 478                 if ((addrs = resolve_host(fullhost, port, 0,
 479                     newname, sizeof(newname))) == NULL) {
 480                         free(fullhost);
 481                         continue;
 482                 }
 483  found:
 484                 /* Remove trailing '.' */
 485                 fullhost[strlen(fullhost) - 1] = '\0';
 486                 /* Follow CNAME if requested */
 487                 if (!check_follow_cname(direct, &fullhost, newname)) {
 488                         debug("Canonicalized hostname \"%s\" => \"%s\"",
 489                             *hostp, fullhost);
 490                 }
 491                 free(*hostp);
 492                 *hostp = fullhost;
 493                 return addrs;
 494         }
 495  notfound:
 496         if (!options.canonicalize_fallback_local)
 497                 fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
 498         debug2("%s: host %s not found in any suffix", __func__, *hostp);
 499         return NULL;
 500 }
 501
 502 /*
 503  * Check the result of hostkey loading, ignoring some errors and
 504  * fatal()ing for others.
 505  */
 506 static void
 507 check_load(int r, const char *path, const char *message)
 508 {
 509         switch (r) {
 510         case 0:
 511                 break;
 512         case SSH_ERR_INTERNAL_ERROR:
 513         case SSH_ERR_ALLOC_FAIL:
 514                 fatal("load %s \"%s\": %s", message, path, ssh_err(r));
 515         case SSH_ERR_SYSTEM_ERROR:
 516                 /* Ignore missing files */
 517                 if (errno == ENOENT)
 518                         break;
 519                 /* FALLTHROUGH */
 520         default:
 521                 error("load %s \"%s\": %s", message, path, ssh_err(r));
 522                 break;
 523         }
 524 }
 525
 526 /*
 527  * Read per-user configuration file.  Ignore the system wide config
 528  * file if the user specifies a config file on the command line.
 529  */
 530 static void
 531 process_config_files(const char *host_name, struct passwd *pw, int post_canon)
 532 {
 533         char buf[PATH_MAX];
 534         int r;
 535
 536         if (config != NULL) {
 537                 if (strcasecmp(config, "none") != 0 &&
 538                     !read_config_file(config, pw, host, host_name, &options,
 539                     SSHCONF_USERCONF | (post_canon ? SSHCONF_POSTCANON : 0)))
 540                         fatal("Can't open user config file %.100s: "
 541                             "%.100s", config, strerror(errno));
 542         } else {
 543                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 544                     _PATH_SSH_USER_CONFFILE);
 545                 if (r > 0 && (size_t)r < sizeof(buf))
 546                         (void)read_config_file(buf, pw, host, host_name,
 547                             &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
 548                             (post_canon ? SSHCONF_POSTCANON : 0));
 549
 550                 /* Read systemwide configuration file after user config. */
 551                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
 552                     host, host_name, &options,
 553                     post_canon ? SSHCONF_POSTCANON : 0);
 554         }
 555 }
 556
 557 /* Rewrite the port number in an addrinfo list of addresses */
 558 static void
 559 set_addrinfo_port(struct addrinfo *addrs, int port)
 560 {
 561         struct addrinfo *addr;
 562
 563         for (addr = addrs; addr != NULL; addr = addr->ai_next) {
 564                 switch (addr->ai_family) {
 565                 case AF_INET:
 566                         ((struct sockaddr_in *)addr->ai_addr)->
 567                             sin_port = htons(port);
 568                         break;
 569                 case AF_INET6:
 570                         ((struct sockaddr_in6 *)addr->ai_addr)->
 571                             sin6_port = htons(port);
 572                         break;
 573                 }
 574         }
 575 }
 576
 577 /*
 578  * Main program for the ssh client.
 579  */
 580 int
 581 main(int ac, char **av)
 582 {
 583         struct ssh *ssh = NULL;
 584         int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
 585         int was_addr, config_test = 0, opt_terminated = 0;
 586         char *p, *cp, *line, *argv0, buf[PATH_MAX], *logfile;
 587         char cname[NI_MAXHOST];
 588         struct stat st;
 589         struct passwd *pw;
 590         extern int optind, optreset;
 591         extern char *optarg;
 592         struct Forward fwd;
 593         struct addrinfo *addrs = NULL;
 594         struct ssh_digest_ctx *md;
 595         u_char conn_hash[SSH_DIGEST_MAX_LENGTH];
 596
 597         ssh_malloc_init();      /* must be called before any mallocs */
 598         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 599         sanitise_stdfd();
 600
 601         __progname = ssh_get_progname(av[0]);
 602
 603 #ifndef HAVE_SETPROCTITLE
 604         /* Prepare for later setproctitle emulation */
 605         /* Save argv so it isn't clobbered by setproctitle() emulation */
 606         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 607         for (i = 0; i < ac; i++)
 608                 saved_av[i] = xstrdup(av[i]);
 609         saved_av[i] = NULL;
 610         compat_init_setproctitle(ac, av);
 611         av = saved_av;
 612 #endif
 613
 614         /*
 615          * Discard other fds that are hanging around. These can cause problem
 616          * with backgrounded ssh processes started by ControlPersist.
 617          */
 618         closefrom(STDERR_FILENO + 1);
 619
 620         /* Get user data. */
 621         pw = getpwuid(getuid());
 622         if (!pw) {
 623                 logit("No user exists for uid %lu", (u_long)getuid());
 624                 exit(255);
 625         }
 626         /* Take a copy of the returned structure. */
 627         pw = pwcopy(pw);
 628
 629         /*
 630          * Set our umask to something reasonable, as some files are created
 631          * with the default umask.  This will make them world-readable but
 632          * writable only by the owner, which is ok for all files for which we
 633          * don't set the modes explicitly.
 634          */
 635         umask(022);
 636
 637         msetlocale();
 638
 639         /*
 640          * Initialize option structure to indicate that no values have been
 641          * set.
 642          */
 643         initialize_options(&options);
 644
 645         /*
 646          * Prepare main ssh transport/connection structures
 647          */
 648         if ((ssh = ssh_alloc_session_state()) == NULL)
 649                 fatal("Couldn't allocate session state");
 650         channel_init_channels(ssh);
 651         active_state = ssh; /* XXX legacy API compat */
 652
 653         /* Parse command-line arguments. */
 654         host = NULL;
 655         use_syslog = 0;
 656         logfile = NULL;
 657         argv0 = av[0];
 658
 659  again:
 660         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 661             "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
 662                 switch (opt) {
 663                 case '1':
 664                         fatal("SSH protocol v.1 is no longer supported");
 665                         break;
 666                 case '2':
 667                         /* Ignored */
 668                         break;
 669                 case '4':
 670                         options.address_family = AF_INET;
 671                         break;
 672                 case '6':
 673                         options.address_family = AF_INET6;
 674                         break;
 675                 case 'n':
 676                         stdin_null_flag = 1;
 677                         break;
 678                 case 'f':
 679                         fork_after_authentication_flag = 1;
 680                         stdin_null_flag = 1;
 681                         break;
 682                 case 'x':
 683                         options.forward_x11 = 0;
 684                         break;
 685                 case 'X':
 686                         options.forward_x11 = 1;
 687                         break;
 688                 case 'y':
 689                         use_syslog = 1;
 690                         break;
 691                 case 'E':
 692                         logfile = optarg;
 693                         break;
 694                 case 'G':
 695                         config_test = 1;
 696                         break;
 697                 case 'Y':
 698                         options.forward_x11 = 1;
 699                         options.forward_x11_trusted = 1;
 700                         break;
 701                 case 'g':
 702                         options.fwd_opts.gateway_ports = 1;
 703                         break;
 704                 case 'O':
 705                         if (options.stdio_forward_host != NULL)
 706                                 fatal("Cannot specify multiplexing "
 707                                     "command with -W");
 708                         else if (muxclient_command != 0)
 709                                 fatal("Multiplexing command already specified");
 710                         if (strcmp(optarg, "check") == 0)
 711                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 712                         else if (strcmp(optarg, "forward") == 0)
 713                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 714                         else if (strcmp(optarg, "exit") == 0)
 715                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 716                         else if (strcmp(optarg, "stop") == 0)
 717                                 muxclient_command = SSHMUX_COMMAND_STOP;
 718                         else if (strcmp(optarg, "cancel") == 0)
 719                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 720                         else if (strcmp(optarg, "proxy") == 0)
 721                                 muxclient_command = SSHMUX_COMMAND_PROXY;
 722                         else
 723                                 fatal("Invalid multiplex command.");
 724                         break;
 725                 case 'P':       /* deprecated */
 726                         break;
 727                 case 'Q':
 728                         cp = NULL;
 729                         if (strcmp(optarg, "cipher") == 0)
 730                                 cp = cipher_alg_list('\n', 0);
 731                         else if (strcmp(optarg, "cipher-auth") == 0)
 732                                 cp = cipher_alg_list('\n', 1);
 733                         else if (strcmp(optarg, "mac") == 0)
 734                                 cp = mac_alg_list('\n');
 735                         else if (strcmp(optarg, "kex") == 0)
 736                                 cp = kex_alg_list('\n');
 737                         else if (strcmp(optarg, "key") == 0)
 738                                 cp = sshkey_alg_list(0, 0, 0, '\n');
 739                         else if (strcmp(optarg, "key-cert") == 0)
 740                                 cp = sshkey_alg_list(1, 0, 0, '\n');
 741                         else if (strcmp(optarg, "key-plain") == 0)
 742                                 cp = sshkey_alg_list(0, 1, 0, '\n');
 743                         else if (strcmp(optarg, "sig") == 0)
 744                                 cp = sshkey_alg_list(0, 1, 1, '\n');
 745                         else if (strcmp(optarg, "protocol-version") == 0)
 746                                 cp = xstrdup("2");
 747                         else if (strcmp(optarg, "help") == 0) {
 748                                 cp = xstrdup(
 749                                     "cipher\ncipher-auth\nkex\nkey\n"
 750                                     "key-cert\nkey-plain\nmac\n"
 751                                     "protocol-version\nsig");
 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, getuid());
 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_STRING);
 822                         else
 823                                 fprintf(stderr, "%s, %s\n", SSH_RELEASE,
 824                                     OPENSSL_VERSION_STRING);
 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         if ((command = sshbuf_new()) == NULL)
1047                 fatal("sshbuf_new failed");
1048
1049         /*
1050          * Save the command to execute on the remote host in a buffer. There
1051          * is no limit on the length of the command, except by the maximum
1052          * packet size.  Also sets the tty flag if there is no command.
1053          */
1054         if (!ac) {
1055                 /* No command specified - execute shell on a tty. */
1056                 if (subsystem_flag) {
1057                         fprintf(stderr,
1058                             "You must specify a subsystem to invoke.\n");
1059                         usage();
1060                 }
1061         } else {
1062                 /* A command has been specified.  Store it into the buffer. */
1063                 for (i = 0; i < ac; i++) {
1064                         if ((r = sshbuf_putf(command, "%s%s",
1065                             i ? " " : "", av[i])) != 0)
1066                                 fatal("%s: buffer error: %s",
1067                                     __func__, ssh_err(r));
1068                 }
1069         }
1070
1071         /*
1072          * Initialize "log" output.  Since we are the client all output
1073          * goes to stderr unless otherwise specified by -y or -E.
1074          */
1075         if (use_syslog && logfile != NULL)
1076                 fatal("Can't specify both -y and -E");
1077         if (logfile != NULL)
1078                 log_redirect_stderr_to(logfile);
1079         log_init(argv0,
1080             options.log_level == SYSLOG_LEVEL_NOT_SET ?
1081             SYSLOG_LEVEL_INFO : options.log_level,
1082             options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1083             SYSLOG_FACILITY_USER : options.log_facility,
1084             !use_syslog);
1085
1086         if (debug_flag)
1087                 /* version_addendum is always NULL at this point */
1088                 logit("%s, %s", SSH_RELEASE, OPENSSL_VERSION_STRING);
1089
1090         /* Parse the configuration files */
1091         process_config_files(host_arg, pw, 0);
1092
1093         /* Hostname canonicalisation needs a few options filled. */
1094         fill_default_options_for_canonicalization(&options);
1095
1096         /* If the user has replaced the hostname then take it into use now */
1097         if (options.hostname != NULL) {
1098                 /* NB. Please keep in sync with readconf.c:match_cfg_line() */
1099                 cp = percent_expand(options.hostname,
1100                     "h", host, (char *)NULL);
1101                 free(host);
1102                 host = cp;
1103                 free(options.hostname);
1104                 options.hostname = xstrdup(host);
1105         }
1106
1107         /* Don't lowercase addresses, they will be explicitly canonicalised */
1108         if ((was_addr = is_addr(host)) == 0)
1109                 lowercase(host);
1110
1111         /*
1112          * Try to canonicalize if requested by configuration or the
1113          * hostname is an address.
1114          */
1115         if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
1116                 addrs = resolve_canonicalize(&host, options.port);
1117
1118         /*
1119          * If CanonicalizePermittedCNAMEs have been specified but
1120          * other canonicalization did not happen (by not being requested
1121          * or by failing with fallback) then the hostname may still be changed
1122          * as a result of CNAME following.
1123          *
1124          * Try to resolve the bare hostname name using the system resolver's
1125          * usual search rules and then apply the CNAME follow rules.
1126          *
1127          * Skip the lookup if a ProxyCommand is being used unless the user
1128          * has specifically requested canonicalisation for this case via
1129          * CanonicalizeHostname=always
1130          */
1131         direct = option_clear_or_none(options.proxy_command) &&
1132             options.jump_host == NULL;
1133         if (addrs == NULL && options.num_permitted_cnames != 0 && (direct ||
1134             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1135                 if ((addrs = resolve_host(host, options.port,
1136                     direct, cname, sizeof(cname))) == NULL) {
1137                         /* Don't fatal proxied host names not in the DNS */
1138                         if (direct)
1139                                 cleanup_exit(255); /* logged in resolve_host */
1140                 } else
1141                         check_follow_cname(direct, &host, cname);
1142         }
1143
1144         /*
1145          * If canonicalisation is enabled then re-parse the configuration
1146          * files as new stanzas may match.
1147          */
1148         if (options.canonicalize_hostname != 0) {
1149                 debug("Re-reading configuration after hostname "
1150                     "canonicalisation");
1151                 free(options.hostname);
1152                 options.hostname = xstrdup(host);
1153                 process_config_files(host_arg, pw, 1);
1154                 /*
1155                  * Address resolution happens early with canonicalisation
1156                  * enabled and the port number may have changed since, so
1157                  * reset it in address list
1158                  */
1159                 if (addrs != NULL && options.port > 0)
1160                         set_addrinfo_port(addrs, options.port);
1161         }
1162
1163         /* Fill configuration defaults. */
1164         fill_default_options(&options);
1165
1166         /*
1167          * If ProxyJump option specified, then construct a ProxyCommand now.
1168          */
1169         if (options.jump_host != NULL) {
1170                 char port_s[8];
1171                 const char *sshbin = argv0;
1172
1173                 /*
1174                  * Try to use SSH indicated by argv[0], but fall back to
1175                  * "ssh" if it appears unavailable.
1176                  */
1177                 if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
1178                         sshbin = "ssh";
1179
1180                 /* Consistency check */
1181                 if (options.proxy_command != NULL)
1182                         fatal("inconsistent options: ProxyCommand+ProxyJump");
1183                 /* Never use FD passing for ProxyJump */
1184                 options.proxy_use_fdpass = 0;
1185                 snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
1186                 xasprintf(&options.proxy_command,
1187                     "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
1188                     sshbin,
1189                     /* Optional "-l user" argument if jump_user set */
1190                     options.jump_user == NULL ? "" : " -l ",
1191                     options.jump_user == NULL ? "" : options.jump_user,
1192                     /* Optional "-p port" argument if jump_port set */
1193                     options.jump_port <= 0 ? "" : " -p ",
1194                     options.jump_port <= 0 ? "" : port_s,
1195                     /* Optional additional jump hosts ",..." */
1196                     options.jump_extra == NULL ? "" : " -J ",
1197                     options.jump_extra == NULL ? "" : options.jump_extra,
1198                     /* Optional "-F" argumment if -F specified */
1199                     config == NULL ? "" : " -F ",
1200                     config == NULL ? "" : config,
1201                     /* Optional "-v" arguments if -v set */
1202                     debug_flag ? " -" : "",
1203                     debug_flag, "vvv",
1204                     /* Mandatory hostname */
1205                     options.jump_host);
1206                 debug("Setting implicit ProxyCommand from ProxyJump: %s",
1207                     options.proxy_command);
1208         }
1209
1210         if (options.port == 0)
1211                 options.port = default_ssh_port();
1212         channel_set_af(ssh, options.address_family);
1213
1214         /* Tidy and check options */
1215         if (options.host_key_alias != NULL)
1216                 lowercase(options.host_key_alias);
1217         if (options.proxy_command != NULL &&
1218             strcmp(options.proxy_command, "-") == 0 &&
1219             options.proxy_use_fdpass)
1220                 fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1221         if (options.control_persist &&
1222             options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1223                 debug("UpdateHostKeys=ask is incompatible with ControlPersist; "
1224                     "disabling");
1225                 options.update_hostkeys = 0;
1226         }
1227         if (options.connection_attempts <= 0)
1228                 fatal("Invalid number of ConnectionAttempts");
1229
1230         if (sshbuf_len(command) != 0 && options.remote_command != NULL)
1231                 fatal("Cannot execute command-line and remote command.");
1232
1233         /* Cannot fork to background if no command. */
1234         if (fork_after_authentication_flag && sshbuf_len(command) == 0 &&
1235             options.remote_command == NULL && !no_shell_flag)
1236                 fatal("Cannot fork into background without a command "
1237                     "to execute.");
1238
1239         /* reinit */
1240         log_init(argv0, options.log_level, options.log_facility, !use_syslog);
1241
1242         if (options.request_tty == REQUEST_TTY_YES ||
1243             options.request_tty == REQUEST_TTY_FORCE)
1244                 tty_flag = 1;
1245
1246         /* Allocate a tty by default if no command specified. */
1247         if (sshbuf_len(command) == 0 && options.remote_command == NULL)
1248                 tty_flag = options.request_tty != REQUEST_TTY_NO;
1249
1250         /* Force no tty */
1251         if (options.request_tty == REQUEST_TTY_NO ||
1252             (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
1253                 tty_flag = 0;
1254         /* Do not allocate a tty if stdin is not a tty. */
1255         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
1256             options.request_tty != REQUEST_TTY_FORCE) {
1257                 if (tty_flag)
1258                         logit("Pseudo-terminal will not be allocated because "
1259                             "stdin is not a terminal.");
1260                 tty_flag = 0;
1261         }
1262
1263         seed_rng();
1264
1265         if (options.user == NULL)
1266                 options.user = xstrdup(pw->pw_name);
1267
1268         /* Set up strings used to percent_expand() arguments */
1269         if (gethostname(thishost, sizeof(thishost)) == -1)
1270                 fatal("gethostname: %s", strerror(errno));
1271         strlcpy(shorthost, thishost, sizeof(shorthost));
1272         shorthost[strcspn(thishost, ".")] = '\0';
1273         snprintf(portstr, sizeof(portstr), "%d", options.port);
1274         snprintf(uidstr, sizeof(uidstr), "%llu",
1275             (unsigned long long)pw->pw_uid);
1276
1277         /* Find canonic host name. */
1278         if (strchr(host, '.') == 0) {
1279                 struct addrinfo hints;
1280                 struct addrinfo *ai = NULL;
1281                 int errgai;
1282                 memset(&hints, 0, sizeof(hints));
1283                 hints.ai_family = options.address_family;
1284                 hints.ai_flags = AI_CANONNAME;
1285                 hints.ai_socktype = SOCK_STREAM;
1286                 errgai = getaddrinfo(host, NULL, &hints, &ai);
1287                 if (errgai == 0) {
1288                         if (ai->ai_canonname != NULL)
1289                                 host = xstrdup(ai->ai_canonname);
1290                         freeaddrinfo(ai);
1291                 }
1292         }
1293
1294         if ((md = ssh_digest_start(SSH_DIGEST_SHA1)) == NULL ||
1295             ssh_digest_update(md, thishost, strlen(thishost)) < 0 ||
1296             ssh_digest_update(md, host, strlen(host)) < 0 ||
1297             ssh_digest_update(md, portstr, strlen(portstr)) < 0 ||
1298             ssh_digest_update(md, options.user, strlen(options.user)) < 0 ||
1299             ssh_digest_final(md, conn_hash, sizeof(conn_hash)) < 0)
1300                 fatal("%s: mux digest failed", __func__);
1301         ssh_digest_free(md);
1302         conn_hash_hex = tohex(conn_hash, ssh_digest_bytes(SSH_DIGEST_SHA1));
1303
1304         /*
1305          * Expand tokens in arguments. NB. LocalCommand is expanded later,
1306          * after port-forwarding is set up, so it may pick up any local
1307          * tunnel interface name allocated.
1308          */
1309         if (options.remote_command != NULL) {
1310                 debug3("expanding RemoteCommand: %s", options.remote_command);
1311                 cp = options.remote_command;
1312                 options.remote_command = percent_expand(cp,
1313                     "C", conn_hash_hex,
1314                     "L", shorthost,
1315                     "d", pw->pw_dir,
1316                     "h", host,
1317                     "i", uidstr,
1318                     "l", thishost,
1319                     "n", host_arg,
1320                     "p", portstr,
1321                     "r", options.user,
1322                     "u", pw->pw_name,
1323                     (char *)NULL);
1324                 debug3("expanded RemoteCommand: %s", options.remote_command);
1325                 free(cp);
1326                 if ((r = sshbuf_put(command, options.remote_command,
1327                     strlen(options.remote_command))) != 0)
1328                         fatal("%s: buffer error: %s", __func__, ssh_err(r));
1329         }
1330
1331         if (options.control_path != NULL) {
1332                 cp = tilde_expand_filename(options.control_path, getuid());
1333                 free(options.control_path);
1334                 options.control_path = percent_expand(cp,
1335                     "C", conn_hash_hex,
1336                     "L", shorthost,
1337                     "h", host,
1338                     "i", uidstr,
1339                     "l", thishost,
1340                     "n", host_arg,
1341                     "p", portstr,
1342                     "r", options.user,
1343                     "u", pw->pw_name,
1344                     "i", uidstr,
1345                     (char *)NULL);
1346                 free(cp);
1347         }
1348
1349         if (config_test) {
1350                 dump_client_config(&options, host);
1351                 exit(0);
1352         }
1353
1354         if (muxclient_command != 0 && options.control_path == NULL)
1355                 fatal("No ControlPath specified for \"-O\" command");
1356         if (options.control_path != NULL) {
1357                 int sock;
1358                 if ((sock = muxclient(options.control_path)) >= 0) {
1359                         ssh_packet_set_connection(ssh, sock, sock);
1360                         packet_set_mux();
1361                         goto skip_connect;
1362                 }
1363         }
1364
1365         /*
1366          * If hostname canonicalisation was not enabled, then we may not
1367          * have yet resolved the hostname. Do so now.
1368          */
1369         if (addrs == NULL && options.proxy_command == NULL) {
1370                 debug2("resolving \"%s\" port %d", host, options.port);
1371                 if ((addrs = resolve_host(host, options.port, 1,
1372                     cname, sizeof(cname))) == NULL)
1373                         cleanup_exit(255); /* resolve_host logs the error */
1374         }
1375
1376         timeout_ms = options.connection_timeout * 1000;
1377
1378         /* Open a connection to the remote host. */
1379         if (ssh_connect(ssh, host, addrs, &hostaddr, options.port,
1380             options.address_family, options.connection_attempts,
1381             &timeout_ms, options.tcp_keep_alive) != 0)
1382                 exit(255);
1383
1384         if (addrs != NULL)
1385                 freeaddrinfo(addrs);
1386
1387         packet_set_timeout(options.server_alive_interval,
1388             options.server_alive_count_max);
1389
1390         ssh = active_state; /* XXX */
1391
1392         if (timeout_ms > 0)
1393                 debug3("timeout: %d ms remain after connect", timeout_ms);
1394
1395         /*
1396          * If we successfully made the connection and we have hostbased auth
1397          * enabled, load the public keys so we can later use the ssh-keysign
1398          * helper to sign challenges.
1399          */
1400         sensitive_data.nkeys = 0;
1401         sensitive_data.keys = NULL;
1402         if (options.hostbased_authentication) {
1403                 sensitive_data.nkeys = 10;
1404                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1405                     sizeof(struct sshkey));
1406
1407                 /* XXX check errors? */
1408 #define L_PUBKEY(p,o) do { \
1409         if ((o) >= sensitive_data.nkeys) \
1410                 fatal("%s pubkey out of array bounds", __func__); \
1411         check_load(sshkey_load_public(p, &(sensitive_data.keys[o]), NULL), \
1412             p, "pubkey"); \
1413 } while (0)
1414 #define L_CERT(p,o) do { \
1415         if ((o) >= sensitive_data.nkeys) \
1416                 fatal("%s cert out of array bounds", __func__); \
1417         check_load(sshkey_load_cert(p, &(sensitive_data.keys[o])), p, "cert"); \
1418 } while (0)
1419
1420                 if (options.hostbased_authentication == 1) {
1421                         L_CERT(_PATH_HOST_ECDSA_KEY_FILE, 0);
1422                         L_CERT(_PATH_HOST_ED25519_KEY_FILE, 1);
1423                         L_CERT(_PATH_HOST_RSA_KEY_FILE, 2);
1424                         L_CERT(_PATH_HOST_DSA_KEY_FILE, 3);
1425                         L_PUBKEY(_PATH_HOST_ECDSA_KEY_FILE, 4);
1426                         L_PUBKEY(_PATH_HOST_ED25519_KEY_FILE, 5);
1427                         L_PUBKEY(_PATH_HOST_RSA_KEY_FILE, 6);
1428                         L_PUBKEY(_PATH_HOST_DSA_KEY_FILE, 7);
1429                         L_CERT(_PATH_HOST_XMSS_KEY_FILE, 8);
1430                         L_PUBKEY(_PATH_HOST_XMSS_KEY_FILE, 9);
1431                 }
1432         }
1433
1434         /* Create ~/.ssh * directory if it doesn't already exist. */
1435         if (config == NULL) {
1436                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1437                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1438                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
1439 #ifdef WITH_SELINUX
1440                         ssh_selinux_setfscreatecon(buf);
1441 #endif
1442                         if (mkdir(buf, 0700) < 0)
1443                                 error("Could not create directory '%.200s'.",
1444                                     buf);
1445 #ifdef WITH_SELINUX
1446                         ssh_selinux_setfscreatecon(NULL);
1447 #endif
1448                 }
1449         }
1450         /* load options.identity_files */
1451         load_public_identity_files(pw);
1452
1453         /* optionally set the SSH_AUTHSOCKET_ENV_NAME variable */
1454         if (options.identity_agent &&
1455             strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
1456                 if (strcmp(options.identity_agent, "none") == 0) {
1457                         unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1458                 } else {
1459                         p = tilde_expand_filename(options.identity_agent,
1460                             getuid());
1461                         cp = percent_expand(p,
1462                             "d", pw->pw_dir,
1463                             "h", host,
1464                             "i", uidstr,
1465                             "l", thishost,
1466                             "r", options.user,
1467                             "u", pw->pw_name,
1468                             (char *)NULL);
1469                         free(p);
1470                         /*
1471                          * If identity_agent represents an environment variable
1472                          * then recheck that it is valid (since processing with
1473                          * percent_expand() may have changed it) and substitute
1474                          * its value.
1475                          */
1476                         if (cp[0] == '$') {
1477                                 if (!valid_env_name(cp + 1)) {
1478                                         fatal("Invalid IdentityAgent "
1479                                             "environment variable name %s", cp);
1480                                 }
1481                                 if ((p = getenv(cp + 1)) == NULL)
1482                                         unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1483                                 else
1484                                         setenv(SSH_AUTHSOCKET_ENV_NAME, p, 1);
1485                         } else {
1486                                 /* identity_agent specifies a path directly */
1487                                 setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
1488                         }
1489                         free(cp);
1490                 }
1491         }
1492
1493         /* Expand ~ in known host file names. */
1494         tilde_expand_paths(options.system_hostfiles,
1495             options.num_system_hostfiles);
1496         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1497
1498         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1499         signal(SIGCHLD, main_sigchld_handler);
1500
1501         /* Log into the remote system.  Never returns if the login fails. */
1502         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1503             options.port, pw, timeout_ms);
1504
1505         if (packet_connection_is_on_socket()) {
1506                 verbose("Authenticated to %s ([%s]:%d).", host,
1507                     ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1508         } else {
1509                 verbose("Authenticated to %s (via proxy).", host);
1510         }
1511
1512         /* We no longer need the private host keys.  Clear them now. */
1513         if (sensitive_data.nkeys != 0) {
1514                 for (i = 0; i < sensitive_data.nkeys; i++) {
1515                         if (sensitive_data.keys[i] != NULL) {
1516                                 /* Destroys contents safely */
1517                                 debug3("clear hostkey %d", i);
1518                                 sshkey_free(sensitive_data.keys[i]);
1519                                 sensitive_data.keys[i] = NULL;
1520                         }
1521                 }
1522                 free(sensitive_data.keys);
1523         }
1524         for (i = 0; i < options.num_identity_files; i++) {
1525                 free(options.identity_files[i]);
1526                 options.identity_files[i] = NULL;
1527                 if (options.identity_keys[i]) {
1528                         sshkey_free(options.identity_keys[i]);
1529                         options.identity_keys[i] = NULL;
1530                 }
1531         }
1532         for (i = 0; i < options.num_certificate_files; i++) {
1533                 free(options.certificate_files[i]);
1534                 options.certificate_files[i] = NULL;
1535         }
1536
1537  skip_connect:
1538         exit_status = ssh_session2(ssh, pw);
1539         packet_close();
1540
1541         if (options.control_path != NULL && muxserver_sock != -1)
1542                 unlink(options.control_path);
1543
1544         /* Kill ProxyCommand if it is running. */
1545         ssh_kill_proxy_command();
1546
1547         return exit_status;
1548 }
1549
1550 static void
1551 control_persist_detach(void)
1552 {
1553         pid_t pid;
1554         int devnull, keep_stderr;
1555
1556         debug("%s: backgrounding master process", __func__);
1557
1558         /*
1559          * master (current process) into the background, and make the
1560          * foreground process a client of the backgrounded master.
1561          */
1562         switch ((pid = fork())) {
1563         case -1:
1564                 fatal("%s: fork: %s", __func__, strerror(errno));
1565         case 0:
1566                 /* Child: master process continues mainloop */
1567                 break;
1568         default:
1569                 /* Parent: set up mux slave to connect to backgrounded master */
1570                 debug2("%s: background process is %ld", __func__, (long)pid);
1571                 stdin_null_flag = ostdin_null_flag;
1572                 options.request_tty = orequest_tty;
1573                 tty_flag = otty_flag;
1574                 close(muxserver_sock);
1575                 muxserver_sock = -1;
1576                 options.control_master = SSHCTL_MASTER_NO;
1577                 muxclient(options.control_path);
1578                 /* muxclient() doesn't return on success. */
1579                 fatal("Failed to connect to new control master");
1580         }
1581         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1582                 error("%s: open(\"/dev/null\"): %s", __func__,
1583                     strerror(errno));
1584         } else {
1585                 keep_stderr = log_is_on_stderr() && debug_flag;
1586                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1587                     dup2(devnull, STDOUT_FILENO) == -1 ||
1588                     (!keep_stderr && dup2(devnull, STDERR_FILENO) == -1))
1589                         error("%s: dup2: %s", __func__, strerror(errno));
1590                 if (devnull > STDERR_FILENO)
1591                         close(devnull);
1592         }
1593         daemon(1, 1);
1594         setproctitle("%s [mux]", options.control_path);
1595 }
1596
1597 /* Do fork() after authentication. Used by "ssh -f" */
1598 static void
1599 fork_postauth(void)
1600 {
1601         if (need_controlpersist_detach)
1602                 control_persist_detach();
1603         debug("forking to background");
1604         fork_after_authentication_flag = 0;
1605         if (daemon(1, 1) < 0)
1606                 fatal("daemon() failed: %.200s", strerror(errno));
1607 }
1608
1609 /* Callback for remote forward global requests */
1610 static void
1611 ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
1612 {
1613         struct Forward *rfwd = (struct Forward *)ctxt;
1614
1615         /* XXX verbose() on failure? */
1616         debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1617             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1618             rfwd->listen_path ? rfwd->listen_path :
1619             rfwd->listen_host ? rfwd->listen_host : "",
1620             (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1621             rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1622             rfwd->connect_host, rfwd->connect_port);
1623         if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1624                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1625                         rfwd->allocated_port = packet_get_int();
1626                         logit("Allocated port %u for remote forward to %s:%d",
1627                             rfwd->allocated_port,
1628                             rfwd->connect_host, rfwd->connect_port);
1629                         channel_update_permission(ssh,
1630                             rfwd->handle, rfwd->allocated_port);
1631                 } else {
1632                         channel_update_permission(ssh, rfwd->handle, -1);
1633                 }
1634         }
1635
1636         if (type == SSH2_MSG_REQUEST_FAILURE) {
1637                 if (options.exit_on_forward_failure) {
1638                         if (rfwd->listen_path != NULL)
1639                                 fatal("Error: remote port forwarding failed "
1640                                     "for listen path %s", rfwd->listen_path);
1641                         else
1642                                 fatal("Error: remote port forwarding failed "
1643                                     "for listen port %d", rfwd->listen_port);
1644                 } else {
1645                         if (rfwd->listen_path != NULL)
1646                                 logit("Warning: remote port forwarding failed "
1647                                     "for listen path %s", rfwd->listen_path);
1648                         else
1649                                 logit("Warning: remote port forwarding failed "
1650                                     "for listen port %d", rfwd->listen_port);
1651                 }
1652         }
1653         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1654                 debug("All remote forwarding requests processed");
1655                 if (fork_after_authentication_flag)
1656                         fork_postauth();
1657         }
1658 }
1659
1660 static void
1661 client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
1662 {
1663         debug("stdio forwarding: done");
1664         cleanup_exit(0);
1665 }
1666
1667 static void
1668 ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1669 {
1670         if (!success)
1671                 fatal("stdio forwarding failed");
1672 }
1673
1674 static void
1675 ssh_init_stdio_forwarding(struct ssh *ssh)
1676 {
1677         Channel *c;
1678         int in, out;
1679
1680         if (options.stdio_forward_host == NULL)
1681                 return;
1682
1683         debug3("%s: %s:%d", __func__, options.stdio_forward_host,
1684             options.stdio_forward_port);
1685
1686         if ((in = dup(STDIN_FILENO)) < 0 ||
1687             (out = dup(STDOUT_FILENO)) < 0)
1688                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1689         if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
1690             options.stdio_forward_port, in, out)) == NULL)
1691                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1692         channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
1693         channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
1694 }
1695
1696 static void
1697 ssh_init_forwarding(struct ssh *ssh, char **ifname)
1698 {
1699         int success = 0;
1700         int i;
1701
1702         /* Initiate local TCP/IP port forwardings. */
1703         for (i = 0; i < options.num_local_forwards; i++) {
1704                 debug("Local connections to %.200s:%d forwarded to remote "
1705                     "address %.200s:%d",
1706                     (options.local_forwards[i].listen_path != NULL) ?
1707                     options.local_forwards[i].listen_path :
1708                     (options.local_forwards[i].listen_host == NULL) ?
1709                     (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1710                     options.local_forwards[i].listen_host,
1711                     options.local_forwards[i].listen_port,
1712                     (options.local_forwards[i].connect_path != NULL) ?
1713                     options.local_forwards[i].connect_path :
1714                     options.local_forwards[i].connect_host,
1715                     options.local_forwards[i].connect_port);
1716                 success += channel_setup_local_fwd_listener(ssh,
1717                     &options.local_forwards[i], &options.fwd_opts);
1718         }
1719         if (i > 0 && success != i && options.exit_on_forward_failure)
1720                 fatal("Could not request local forwarding.");
1721         if (i > 0 && success == 0)
1722                 error("Could not request local forwarding.");
1723
1724         /* Initiate remote TCP/IP port forwardings. */
1725         for (i = 0; i < options.num_remote_forwards; i++) {
1726                 debug("Remote connections from %.200s:%d forwarded to "
1727                     "local address %.200s:%d",
1728                     (options.remote_forwards[i].listen_path != NULL) ?
1729                     options.remote_forwards[i].listen_path :
1730                     (options.remote_forwards[i].listen_host == NULL) ?
1731                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1732                     options.remote_forwards[i].listen_port,
1733                     (options.remote_forwards[i].connect_path != NULL) ?
1734                     options.remote_forwards[i].connect_path :
1735                     options.remote_forwards[i].connect_host,
1736                     options.remote_forwards[i].connect_port);
1737                 options.remote_forwards[i].handle =
1738                     channel_request_remote_forwarding(ssh,
1739                     &options.remote_forwards[i]);
1740                 if (options.remote_forwards[i].handle < 0) {
1741                         if (options.exit_on_forward_failure)
1742                                 fatal("Could not request remote forwarding.");
1743                         else
1744                                 logit("Warning: Could not request remote "
1745                                     "forwarding.");
1746                 } else {
1747                         client_register_global_confirm(
1748                             ssh_confirm_remote_forward,
1749                             &options.remote_forwards[i]);
1750                 }
1751         }
1752
1753         /* Initiate tunnel forwarding. */
1754         if (options.tun_open != SSH_TUNMODE_NO) {
1755                 if ((*ifname = client_request_tun_fwd(ssh,
1756                     options.tun_open, options.tun_local,
1757                     options.tun_remote)) == NULL) {
1758                         if (options.exit_on_forward_failure)
1759                                 fatal("Could not request tunnel forwarding.");
1760                         else
1761                                 error("Could not request tunnel forwarding.");
1762                 }
1763         }
1764 }
1765
1766 static void
1767 check_agent_present(void)
1768 {
1769         int r;
1770
1771         if (options.forward_agent) {
1772                 /* Clear agent forwarding if we don't have an agent. */
1773                 if ((r = ssh_get_authentication_socket(NULL)) != 0) {
1774                         options.forward_agent = 0;
1775                         if (r != SSH_ERR_AGENT_NOT_PRESENT)
1776                                 debug("ssh_get_authentication_socket: %s",
1777                                     ssh_err(r));
1778                 }
1779         }
1780 }
1781
1782 static void
1783 ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
1784 {
1785         extern char **environ;
1786         const char *display;
1787         int interactive = tty_flag;
1788         char *proto = NULL, *data = NULL;
1789
1790         if (!success)
1791                 return; /* No need for error message, channels code sens one */
1792
1793         display = getenv("DISPLAY");
1794         if (display == NULL && options.forward_x11)
1795                 debug("X11 forwarding requested but DISPLAY not set");
1796         if (options.forward_x11 && client_x11_get_proto(ssh, display,
1797             options.xauth_location, options.forward_x11_trusted,
1798             options.forward_x11_timeout, &proto, &data) == 0) {
1799                 /* Request forwarding with authentication spoofing. */
1800                 debug("Requesting X11 forwarding with authentication "
1801                     "spoofing.");
1802                 x11_request_forwarding_with_spoofing(ssh, id, display, proto,
1803                     data, 1);
1804                 client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
1805                 /* XXX exit_on_forward_failure */
1806                 interactive = 1;
1807         }
1808
1809         check_agent_present();
1810         if (options.forward_agent) {
1811                 debug("Requesting authentication agent forwarding.");
1812                 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1813                 packet_send();
1814         }
1815
1816         /* Tell the packet module whether this is an interactive session. */
1817         packet_set_interactive(interactive,
1818             options.ip_qos_interactive, options.ip_qos_bulk);
1819
1820         client_session2_setup(ssh, id, tty_flag, subsystem_flag, getenv("TERM"),
1821             NULL, fileno(stdin), command, environ);
1822 }
1823
1824 /* open new channel for a session */
1825 static int
1826 ssh_session2_open(struct ssh *ssh)
1827 {
1828         Channel *c;
1829         int window, packetmax, in, out, err;
1830
1831         if (stdin_null_flag) {
1832                 in = open(_PATH_DEVNULL, O_RDONLY);
1833         } else {
1834                 in = dup(STDIN_FILENO);
1835         }
1836         out = dup(STDOUT_FILENO);
1837         err = dup(STDERR_FILENO);
1838
1839         if (in < 0 || out < 0 || err < 0)
1840                 fatal("dup() in/out/err failed");
1841
1842         /* enable nonblocking unless tty */
1843         if (!isatty(in))
1844                 set_nonblock(in);
1845         if (!isatty(out))
1846                 set_nonblock(out);
1847         if (!isatty(err))
1848                 set_nonblock(err);
1849
1850         window = CHAN_SES_WINDOW_DEFAULT;
1851         packetmax = CHAN_SES_PACKET_DEFAULT;
1852         if (tty_flag) {
1853                 window >>= 1;
1854                 packetmax >>= 1;
1855         }
1856         c = channel_new(ssh,
1857             "session", SSH_CHANNEL_OPENING, in, out, err,
1858             window, packetmax, CHAN_EXTENDED_WRITE,
1859             "client-session", /*nonblock*/0);
1860
1861         debug3("%s: channel_new: %d", __func__, c->self);
1862
1863         channel_send_open(ssh, c->self);
1864         if (!no_shell_flag)
1865                 channel_register_open_confirm(ssh, c->self,
1866                     ssh_session2_setup, NULL);
1867
1868         return c->self;
1869 }
1870
1871 static int
1872 ssh_session2(struct ssh *ssh, struct passwd *pw)
1873 {
1874         int devnull, id = -1;
1875         char *cp, *tun_fwd_ifname = NULL;
1876
1877         /* XXX should be pre-session */
1878         if (!options.control_persist)
1879                 ssh_init_stdio_forwarding(ssh);
1880
1881         ssh_init_forwarding(ssh, &tun_fwd_ifname);
1882
1883         if (options.local_command != NULL) {
1884                 debug3("expanding LocalCommand: %s", options.local_command);
1885                 cp = options.local_command;
1886                 options.local_command = percent_expand(cp,
1887                     "C", conn_hash_hex,
1888                     "L", shorthost,
1889                     "d", pw->pw_dir,
1890                     "h", host,
1891                     "i", uidstr,
1892                     "l", thishost,
1893                     "n", host_arg,
1894                     "p", portstr,
1895                     "r", options.user,
1896                     "u", pw->pw_name,
1897                     "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
1898                     (char *)NULL);
1899                 debug3("expanded LocalCommand: %s", options.local_command);
1900                 free(cp);
1901         }
1902
1903         /* Start listening for multiplex clients */
1904         if (!packet_get_mux())
1905                 muxserver_listen(ssh);
1906
1907         /*
1908          * If we are in control persist mode and have a working mux listen
1909          * socket, then prepare to background ourselves and have a foreground
1910          * client attach as a control slave.
1911          * NB. we must save copies of the flags that we override for
1912          * the backgrounding, since we defer attachment of the slave until
1913          * after the connection is fully established (in particular,
1914          * async rfwd replies have been received for ExitOnForwardFailure).
1915          */
1916         if (options.control_persist && muxserver_sock != -1) {
1917                 ostdin_null_flag = stdin_null_flag;
1918                 ono_shell_flag = no_shell_flag;
1919                 orequest_tty = options.request_tty;
1920                 otty_flag = tty_flag;
1921                 stdin_null_flag = 1;
1922                 no_shell_flag = 1;
1923                 tty_flag = 0;
1924                 if (!fork_after_authentication_flag)
1925                         need_controlpersist_detach = 1;
1926                 fork_after_authentication_flag = 1;
1927         }
1928         /*
1929          * ControlPersist mux listen socket setup failed, attempt the
1930          * stdio forward setup that we skipped earlier.
1931          */
1932         if (options.control_persist && muxserver_sock == -1)
1933                 ssh_init_stdio_forwarding(ssh);
1934
1935         if (!no_shell_flag)
1936                 id = ssh_session2_open(ssh);
1937         else {
1938                 packet_set_interactive(
1939                     options.control_master == SSHCTL_MASTER_NO,
1940                     options.ip_qos_interactive, options.ip_qos_bulk);
1941         }
1942
1943         /* If we don't expect to open a new session, then disallow it */
1944         if (options.control_master == SSHCTL_MASTER_NO &&
1945             (datafellows & SSH_NEW_OPENSSH)) {
1946                 debug("Requesting no-more-sessions@openssh.com");
1947                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1948                 packet_put_cstring("no-more-sessions@openssh.com");
1949                 packet_put_char(0);
1950                 packet_send();
1951         }
1952
1953         /* Execute a local command */
1954         if (options.local_command != NULL &&
1955             options.permit_local_command)
1956                 ssh_local_cmd(options.local_command);
1957
1958         /*
1959          * stdout is now owned by the session channel; clobber it here
1960          * so future channel closes are propagated to the local fd.
1961          * NB. this can only happen after LocalCommand has completed,
1962          * as it may want to write to stdout.
1963          */
1964         if (!need_controlpersist_detach) {
1965                 if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
1966                         error("%s: open %s: %s", __func__,
1967                             _PATH_DEVNULL, strerror(errno));
1968                 if (dup2(devnull, STDOUT_FILENO) < 0)
1969                         fatal("%s: dup2() stdout failed", __func__);
1970                 if (devnull > STDERR_FILENO)
1971                         close(devnull);
1972         }
1973
1974         /*
1975          * If requested and we are not interested in replies to remote
1976          * forwarding requests, then let ssh continue in the background.
1977          */
1978         if (fork_after_authentication_flag) {
1979                 if (options.exit_on_forward_failure &&
1980                     options.num_remote_forwards > 0) {
1981                         debug("deferring postauth fork until remote forward "
1982                             "confirmation received");
1983                 } else
1984                         fork_postauth();
1985         }
1986
1987         return client_loop(ssh, tty_flag, tty_flag ?
1988             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1989 }
1990
1991 /* Loads all IdentityFile and CertificateFile keys */
1992 static void
1993 load_public_identity_files(struct passwd *pw)
1994 {
1995         char *filename, *cp;
1996         struct sshkey *public;
1997         int i;
1998         u_int n_ids, n_certs;
1999         char *identity_files[SSH_MAX_IDENTITY_FILES];
2000         struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
2001         int identity_file_userprovided[SSH_MAX_IDENTITY_FILES];
2002         char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
2003         struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
2004         int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES];
2005 #ifdef ENABLE_PKCS11
2006         struct sshkey **keys;
2007         int nkeys;
2008 #endif /* PKCS11 */
2009
2010         n_ids = n_certs = 0;
2011         memset(identity_files, 0, sizeof(identity_files));
2012         memset(identity_keys, 0, sizeof(identity_keys));
2013         memset(identity_file_userprovided, 0,
2014             sizeof(identity_file_userprovided));
2015         memset(certificate_files, 0, sizeof(certificate_files));
2016         memset(certificates, 0, sizeof(certificates));
2017         memset(certificate_file_userprovided, 0,
2018             sizeof(certificate_file_userprovided));
2019
2020 #ifdef ENABLE_PKCS11
2021         if (options.pkcs11_provider != NULL &&
2022             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
2023             (pkcs11_init(!options.batch_mode) == 0) &&
2024             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
2025             &keys)) > 0) {
2026                 for (i = 0; i < nkeys; i++) {
2027                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
2028                                 sshkey_free(keys[i]);
2029                                 continue;
2030                         }
2031                         identity_keys[n_ids] = keys[i];
2032                         identity_files[n_ids] =
2033                             xstrdup(options.pkcs11_provider); /* XXX */
2034                         n_ids++;
2035                 }
2036                 free(keys);
2037         }
2038 #endif /* ENABLE_PKCS11 */
2039         for (i = 0; i < options.num_identity_files; i++) {
2040                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
2041                     strcasecmp(options.identity_files[i], "none") == 0) {
2042                         free(options.identity_files[i]);
2043                         options.identity_files[i] = NULL;
2044                         continue;
2045                 }
2046                 cp = tilde_expand_filename(options.identity_files[i], getuid());
2047                 filename = percent_expand(cp, "d", pw->pw_dir,
2048                     "u", pw->pw_name, "l", thishost, "h", host,
2049                     "r", options.user, (char *)NULL);
2050                 free(cp);
2051                 check_load(sshkey_load_public(filename, &public, NULL),
2052                     filename, "pubkey");
2053                 debug("identity file %s type %d", filename,
2054                     public ? public->type : -1);
2055                 free(options.identity_files[i]);
2056                 identity_files[n_ids] = filename;
2057                 identity_keys[n_ids] = public;
2058                 identity_file_userprovided[n_ids] =
2059                     options.identity_file_userprovided[i];
2060                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2061                         continue;
2062
2063                 /*
2064                  * If no certificates have been explicitly listed then try
2065                  * to add the default certificate variant too.
2066                  */
2067                 if (options.num_certificate_files != 0)
2068                         continue;
2069                 xasprintf(&cp, "%s-cert", filename);
2070                 check_load(sshkey_load_public(cp, &public, NULL),
2071                     filename, "pubkey");
2072                 debug("identity file %s type %d", cp,
2073                     public ? public->type : -1);
2074                 if (public == NULL) {
2075                         free(cp);
2076                         continue;
2077                 }
2078                 if (!sshkey_is_cert(public)) {
2079                         debug("%s: key %s type %s is not a certificate",
2080                             __func__, cp, sshkey_type(public));
2081                         sshkey_free(public);
2082                         free(cp);
2083                         continue;
2084                 }
2085                 /* NB. leave filename pointing to private key */
2086                 identity_files[n_ids] = xstrdup(filename);
2087                 identity_keys[n_ids] = public;
2088                 identity_file_userprovided[n_ids] =
2089                     options.identity_file_userprovided[i];
2090                 n_ids++;
2091         }
2092
2093         if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
2094                 fatal("%s: too many certificates", __func__);
2095         for (i = 0; i < options.num_certificate_files; i++) {
2096                 cp = tilde_expand_filename(options.certificate_files[i],
2097                     getuid());
2098                 filename = percent_expand(cp,
2099                     "d", pw->pw_dir,
2100                     "h", host,
2101                     "i", uidstr,
2102                     "l", thishost,
2103                     "r", options.user,
2104                     "u", pw->pw_name,
2105                     (char *)NULL);
2106                 free(cp);
2107
2108                 check_load(sshkey_load_public(filename, &public, NULL),
2109                     filename, "certificate");
2110                 debug("certificate file %s type %d", filename,
2111                     public ? public->type : -1);
2112                 free(options.certificate_files[i]);
2113                 options.certificate_files[i] = NULL;
2114                 if (public == NULL) {
2115                         free(filename);
2116                         continue;
2117                 }
2118                 if (!sshkey_is_cert(public)) {
2119                         debug("%s: key %s type %s is not a certificate",
2120                             __func__, filename, sshkey_type(public));
2121                         sshkey_free(public);
2122                         free(filename);
2123                         continue;
2124                 }
2125                 certificate_files[n_certs] = filename;
2126                 certificates[n_certs] = public;
2127                 certificate_file_userprovided[n_certs] =
2128                     options.certificate_file_userprovided[i];
2129                 ++n_certs;
2130         }
2131
2132         options.num_identity_files = n_ids;
2133         memcpy(options.identity_files, identity_files, sizeof(identity_files));
2134         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2135         memcpy(options.identity_file_userprovided,
2136             identity_file_userprovided, sizeof(identity_file_userprovided));
2137
2138         options.num_certificate_files = n_certs;
2139         memcpy(options.certificate_files,
2140             certificate_files, sizeof(certificate_files));
2141         memcpy(options.certificates, certificates, sizeof(certificates));
2142         memcpy(options.certificate_file_userprovided,
2143             certificate_file_userprovided,
2144             sizeof(certificate_file_userprovided));
2145 }
2146
2147 static void
2148 main_sigchld_handler(int sig)
2149 {
2150         int save_errno = errno;
2151         pid_t pid;
2152         int status;
2153
2154         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2155             (pid < 0 && errno == EINTR))
2156                 ;
2157         errno = save_errno;
2158 }