crypto/openssh/ssh.c

   1 /* $OpenBSD: ssh.c,v 1.401 2014/02/26 20:18:37 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Ssh client program.  This program can be used to log into a remote machine.
   7  * The software supports strong authentication, encryption, and forwarding
   8  * of X11, TCP/IP, and authentication connections.
   9  *
  10  * As far as I am concerned, the code I have written for this software
  11  * can be used freely for any purpose.  Any derived versions of this
  12  * software must be clearly marked as such, and if the derived work is
  13  * incompatible with the protocol description in the RFC file, it must be
  14  * called by a name other than "ssh" or "Secure Shell".
  15  *
  16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
  17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
  18  *
  19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
  20  * in Canada (German citizen).
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the above copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  *
  31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  41  */
  42
  43 #include "includes.h"
  44 __RCSID("$FreeBSD$");
  45
  46 #include <sys/types.h>
  47 #ifdef HAVE_SYS_STAT_H
  48 # include <sys/stat.h>
  49 #endif
  50 #include <sys/resource.h>
  51 #include <sys/ioctl.h>
  52 #include <sys/param.h>
  53 #include <sys/socket.h>
  54 #include <sys/wait.h>
  55
  56 #include <ctype.h>
  57 #include <errno.h>
  58 #include <fcntl.h>
  59 #include <netdb.h>
  60 #ifdef HAVE_PATHS_H
  61 #include <paths.h>
  62 #endif
  63 #include <pwd.h>
  64 #include <signal.h>
  65 #include <stdarg.h>
  66 #include <stddef.h>
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <string.h>
  70 #include <unistd.h>
  71
  72 #include <netinet/in.h>
  73 #include <arpa/inet.h>
  74
  75 #include <openssl/evp.h>
  76 #include <openssl/err.h>
  77 #include "openbsd-compat/openssl-compat.h"
  78 #include "openbsd-compat/sys-queue.h"
  79
  80 #include "xmalloc.h"
  81 #include "ssh.h"
  82 #include "ssh1.h"
  83 #include "ssh2.h"
  84 #include "canohost.h"
  85 #include "compat.h"
  86 #include "cipher.h"
  87 #include "packet.h"
  88 #include "buffer.h"
  89 #include "channels.h"
  90 #include "key.h"
  91 #include "authfd.h"
  92 #include "authfile.h"
  93 #include "pathnames.h"
  94 #include "dispatch.h"
  95 #include "clientloop.h"
  96 #include "log.h"
  97 #include "readconf.h"
  98 #include "sshconnect.h"
  99 #include "misc.h"
 100 #include "kex.h"
 101 #include "mac.h"
 102 #include "sshpty.h"
 103 #include "match.h"
 104 #include "msg.h"
 105 #include "uidswap.h"
 106 #include "roaming.h"
 107 #include "version.h"
 108
 109 #ifdef ENABLE_PKCS11
 110 #include "ssh-pkcs11.h"
 111 #endif
 112
 113 extern char *__progname;
 114
 115 /* Saves a copy of argv for setproctitle emulation */
 116 #ifndef HAVE_SETPROCTITLE
 117 static char **saved_av;
 118 #endif
 119
 120 /* Flag indicating whether debug mode is on.  May be set on the command line. */
 121 int debug_flag = 0;
 122
 123 /* Flag indicating whether a tty should be requested */
 124 int tty_flag = 0;
 125
 126 /* don't exec a shell */
 127 int no_shell_flag = 0;
 128
 129 /*
 130  * Flag indicating that nothing should be read from stdin.  This can be set
 131  * on the command line.
 132  */
 133 int stdin_null_flag = 0;
 134
 135 /*
 136  * Flag indicating that the current process should be backgrounded and
 137  * a new slave launched in the foreground for ControlPersist.
 138  */
 139 int need_controlpersist_detach = 0;
 140
 141 /* Copies of flags for ControlPersist foreground slave */
 142 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
 143
 144 /*
 145  * Flag indicating that ssh should fork after authentication.  This is useful
 146  * so that the passphrase can be entered manually, and then ssh goes to the
 147  * background.
 148  */
 149 int fork_after_authentication_flag = 0;
 150
 151 /* forward stdio to remote host and port */
 152 char *stdio_forward_host = NULL;
 153 int stdio_forward_port = 0;
 154
 155 /*
 156  * General data structure for command line options and options configurable
 157  * in configuration files.  See readconf.h.
 158  */
 159 Options options;
 160
 161 /* optional user configfile */
 162 char *config = NULL;
 163
 164 /*
 165  * Name of the host we are connecting to.  This is the name given on the
 166  * command line, or the HostName specified for the user-supplied name in a
 167  * configuration file.
 168  */
 169 char *host;
 170
 171 /* socket address the host resolves to */
 172 struct sockaddr_storage hostaddr;
 173
 174 /* Private host keys. */
 175 Sensitive sensitive_data;
 176
 177 /* Original real UID. */
 178 uid_t original_real_uid;
 179 uid_t original_effective_uid;
 180
 181 /* command to be executed */
 182 Buffer command;
 183
 184 /* Should we execute a command or invoke a subsystem? */
 185 int subsystem_flag = 0;
 186
 187 /* # of replies received for global requests */
 188 static int remote_forward_confirms_received = 0;
 189
 190 /* mux.c */
 191 extern int muxserver_sock;
 192 extern u_int muxclient_command;
 193
 194 /* Prints a help message to the user.  This function never returns. */
 195
 196 static void
 197 usage(void)
 198 {
 199         fprintf(stderr,
 200 "usage: ssh [-1246AaCfgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
 201 "           [-D [bind_address:]port] [-E log_file] [-e escape_char]\n"
 202 "           [-F configfile] [-I pkcs11] [-i identity_file]\n"
 203 "           [-L [bind_address:]port:host:hostport] [-l login_name] [-m mac_spec]\n"
 204 "           [-O ctl_cmd] [-o option] [-p port]\n"
 205 "           [-Q cipher | cipher-auth | mac | kex | key]\n"
 206 "           [-R [bind_address:]port:host:hostport] [-S ctl_path] [-W host:port]\n"
 207 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
 208         );
 209         exit(255);
 210 }
 211
 212 static int ssh_session(void);
 213 static int ssh_session2(void);
 214 static void load_public_identity_files(void);
 215 static void main_sigchld_handler(int);
 216
 217 /* from muxclient.c */
 218 void muxclient(const char *);
 219 void muxserver_listen(void);
 220
 221 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
 222 static void
 223 tilde_expand_paths(char **paths, u_int num_paths)
 224 {
 225         u_int i;
 226         char *cp;
 227
 228         for (i = 0; i < num_paths; i++) {
 229                 cp = tilde_expand_filename(paths[i], original_real_uid);
 230                 free(paths[i]);
 231                 paths[i] = cp;
 232         }
 233 }
 234
 235 /*
 236  * Attempt to resolve a host name / port to a set of addresses and
 237  * optionally return any CNAMEs encountered along the way.
 238  * Returns NULL on failure.
 239  * NB. this function must operate with a options having undefined members.
 240  */
 241 static struct addrinfo *
 242 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
 243 {
 244         char strport[NI_MAXSERV];
 245         struct addrinfo hints, *res;
 246         int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
 247
 248         if (port <= 0)
 249                 port = default_ssh_port();
 250
 251         snprintf(strport, sizeof strport, "%u", port);
 252         memset(&hints, 0, sizeof(hints));
 253         hints.ai_family = options.address_family == -1 ?
 254             AF_UNSPEC : options.address_family;
 255         hints.ai_socktype = SOCK_STREAM;
 256         if (cname != NULL)
 257                 hints.ai_flags = AI_CANONNAME;
 258         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
 259                 if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
 260                         loglevel = SYSLOG_LEVEL_ERROR;
 261                 do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
 262                     __progname, name, ssh_gai_strerror(gaierr));
 263                 return NULL;
 264         }
 265         if (cname != NULL && res->ai_canonname != NULL) {
 266                 if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
 267                         error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
 268                             __func__, name,  res->ai_canonname, (u_long)clen);
 269                         if (clen > 0)
 270                                 *cname = '\0';
 271                 }
 272         }
 273         return res;
 274 }
 275
 276 /*
 277  * Check whether the cname is a permitted replacement for the hostname
 278  * and perform the replacement if it is.
 279  * NB. this function must operate with a options having undefined members.
 280  */
 281 static int
 282 check_follow_cname(char **namep, const char *cname)
 283 {
 284         int i;
 285         struct allowed_cname *rule;
 286
 287         if (*cname == '\0' || options.num_permitted_cnames == 0 ||
 288             strcmp(*namep, cname) == 0)
 289                 return 0;
 290         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 291                 return 0;
 292         /*
 293          * Don't attempt to canonicalize names that will be interpreted by
 294          * a proxy unless the user specifically requests so.
 295          */
 296         if (!option_clear_or_none(options.proxy_command) &&
 297             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 298                 return 0;
 299         debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
 300         for (i = 0; i < options.num_permitted_cnames; i++) {
 301                 rule = options.permitted_cnames + i;
 302                 if (match_pattern_list(*namep, rule->source_list,
 303                     strlen(rule->source_list), 1) != 1 ||
 304                     match_pattern_list(cname, rule->target_list,
 305                     strlen(rule->target_list), 1) != 1)
 306                         continue;
 307                 verbose("Canonicalized DNS aliased hostname "
 308                     "\"%s\" => \"%s\"", *namep, cname);
 309                 free(*namep);
 310                 *namep = xstrdup(cname);
 311                 return 1;
 312         }
 313         return 0;
 314 }
 315
 316 /*
 317  * Attempt to resolve the supplied hostname after applying the user's
 318  * canonicalization rules. Returns the address list for the host or NULL
 319  * if no name was found after canonicalization.
 320  * NB. this function must operate with a options having undefined members.
 321  */
 322 static struct addrinfo *
 323 resolve_canonicalize(char **hostp, int port)
 324 {
 325         int i, ndots;
 326         char *cp, *fullhost, cname_target[NI_MAXHOST];
 327         struct addrinfo *addrs;
 328
 329         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
 330                 return NULL;
 331
 332         /*
 333          * Don't attempt to canonicalize names that will be interpreted by
 334          * a proxy unless the user specifically requests so.
 335          */
 336         if (!option_clear_or_none(options.proxy_command) &&
 337             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
 338                 return NULL;
 339
 340         /* Don't apply canonicalization to sufficiently-qualified hostnames */
 341         ndots = 0;
 342         for (cp = *hostp; *cp != '\0'; cp++) {
 343                 if (*cp == '.')
 344                         ndots++;
 345         }
 346         if (ndots > options.canonicalize_max_dots) {
 347                 debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
 348                     __func__, *hostp, options.canonicalize_max_dots);
 349                 return NULL;
 350         }
 351         /* Attempt each supplied suffix */
 352         for (i = 0; i < options.num_canonical_domains; i++) {
 353                 *cname_target = '\0';
 354                 xasprintf(&fullhost, "%s.%s.", *hostp,
 355                     options.canonical_domains[i]);
 356                 debug3("%s: attempting \"%s\" => \"%s\"", __func__,
 357                     *hostp, fullhost);
 358                 if ((addrs = resolve_host(fullhost, port, 0,
 359                     cname_target, sizeof(cname_target))) == NULL) {
 360                         free(fullhost);
 361                         continue;
 362                 }
 363                 /* Remove trailing '.' */
 364                 fullhost[strlen(fullhost) - 1] = '\0';
 365                 /* Follow CNAME if requested */
 366                 if (!check_follow_cname(&fullhost, cname_target)) {
 367                         debug("Canonicalized hostname \"%s\" => \"%s\"",
 368                             *hostp, fullhost);
 369                 }
 370                 free(*hostp);
 371                 *hostp = fullhost;
 372                 return addrs;
 373         }
 374         if (!options.canonicalize_fallback_local)
 375                 fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
 376         debug2("%s: host %s not found in any suffix", __func__, *hostp);
 377         return NULL;
 378 }
 379
 380 /*
 381  * Read per-user configuration file.  Ignore the system wide config
 382  * file if the user specifies a config file on the command line.
 383  */
 384 static void
 385 process_config_files(struct passwd *pw)
 386 {
 387         char buf[MAXPATHLEN];
 388         int r;
 389
 390         if (config != NULL) {
 391                 if (strcasecmp(config, "none") != 0 &&
 392                     !read_config_file(config, pw, host, &options,
 393                     SSHCONF_USERCONF))
 394                         fatal("Can't open user config file %.100s: "
 395                             "%.100s", config, strerror(errno));
 396         } else {
 397                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
 398                     _PATH_SSH_USER_CONFFILE);
 399                 if (r > 0 && (size_t)r < sizeof(buf))
 400                         (void)read_config_file(buf, pw, host, &options,
 401                              SSHCONF_CHECKPERM|SSHCONF_USERCONF);
 402
 403                 /* Read systemwide configuration file after user config. */
 404                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw, host,
 405                     &options, 0);
 406         }
 407 }
 408
 409 /*
 410  * Main program for the ssh client.
 411  */
 412 int
 413 main(int ac, char **av)
 414 {
 415         int i, r, opt, exit_status, use_syslog;
 416         char *p, *cp, *line, *argv0, buf[MAXPATHLEN], *host_arg, *logfile;
 417         char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
 418         char cname[NI_MAXHOST];
 419         struct stat st;
 420         struct passwd *pw;
 421         int timeout_ms;
 422         extern int optind, optreset;
 423         extern char *optarg;
 424         Forward fwd;
 425         struct addrinfo *addrs = NULL;
 426
 427         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
 428         sanitise_stdfd();
 429
 430         __progname = ssh_get_progname(av[0]);
 431
 432 #ifndef HAVE_SETPROCTITLE
 433         /* Prepare for later setproctitle emulation */
 434         /* Save argv so it isn't clobbered by setproctitle() emulation */
 435         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
 436         for (i = 0; i < ac; i++)
 437                 saved_av[i] = xstrdup(av[i]);
 438         saved_av[i] = NULL;
 439         compat_init_setproctitle(ac, av);
 440         av = saved_av;
 441 #endif
 442
 443         /*
 444          * Discard other fds that are hanging around. These can cause problem
 445          * with backgrounded ssh processes started by ControlPersist.
 446          */
 447         closefrom(STDERR_FILENO + 1);
 448
 449         /*
 450          * Save the original real uid.  It will be needed later (uid-swapping
 451          * may clobber the real uid).
 452          */
 453         original_real_uid = getuid();
 454         original_effective_uid = geteuid();
 455
 456         /*
 457          * Use uid-swapping to give up root privileges for the duration of
 458          * option processing.  We will re-instantiate the rights when we are
 459          * ready to create the privileged port, and will permanently drop
 460          * them when the port has been created (actually, when the connection
 461          * has been made, as we may need to create the port several times).
 462          */
 463         PRIV_END;
 464
 465 #ifdef HAVE_SETRLIMIT
 466         /* If we are installed setuid root be careful to not drop core. */
 467         if (original_real_uid != original_effective_uid) {
 468                 struct rlimit rlim;
 469                 rlim.rlim_cur = rlim.rlim_max = 0;
 470                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
 471                         fatal("setrlimit failed: %.100s", strerror(errno));
 472         }
 473 #endif
 474         /* Get user data. */
 475         pw = getpwuid(original_real_uid);
 476         if (!pw) {
 477                 logit("No user exists for uid %lu", (u_long)original_real_uid);
 478                 exit(255);
 479         }
 480         /* Take a copy of the returned structure. */
 481         pw = pwcopy(pw);
 482
 483         /*
 484          * Set our umask to something reasonable, as some files are created
 485          * with the default umask.  This will make them world-readable but
 486          * writable only by the owner, which is ok for all files for which we
 487          * don't set the modes explicitly.
 488          */
 489         umask(022);
 490
 491         /*
 492          * Initialize option structure to indicate that no values have been
 493          * set.
 494          */
 495         initialize_options(&options);
 496
 497         /* Parse command-line arguments. */
 498         host = NULL;
 499         use_syslog = 0;
 500         logfile = NULL;
 501         argv0 = av[0];
 502
 503  again:
 504         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
 505             "ACD:E:F:I:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
 506                 switch (opt) {
 507                 case '1':
 508                         options.protocol = SSH_PROTO_1;
 509                         break;
 510                 case '2':
 511                         options.protocol = SSH_PROTO_2;
 512                         break;
 513                 case '4':
 514                         options.address_family = AF_INET;
 515                         break;
 516                 case '6':
 517                         options.address_family = AF_INET6;
 518                         break;
 519                 case 'n':
 520                         stdin_null_flag = 1;
 521                         break;
 522                 case 'f':
 523                         fork_after_authentication_flag = 1;
 524                         stdin_null_flag = 1;
 525                         break;
 526                 case 'x':
 527                         options.forward_x11 = 0;
 528                         break;
 529                 case 'X':
 530                         options.forward_x11 = 1;
 531                         break;
 532                 case 'y':
 533                         use_syslog = 1;
 534                         break;
 535                 case 'E':
 536                         logfile = xstrdup(optarg);
 537                         break;
 538                 case 'Y':
 539                         options.forward_x11 = 1;
 540                         options.forward_x11_trusted = 1;
 541                         break;
 542                 case 'g':
 543                         options.gateway_ports = 1;
 544                         break;
 545                 case 'O':
 546                         if (stdio_forward_host != NULL)
 547                                 fatal("Cannot specify multiplexing "
 548                                     "command with -W");
 549                         else if (muxclient_command != 0)
 550                                 fatal("Multiplexing command already specified");
 551                         if (strcmp(optarg, "check") == 0)
 552                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
 553                         else if (strcmp(optarg, "forward") == 0)
 554                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
 555                         else if (strcmp(optarg, "exit") == 0)
 556                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
 557                         else if (strcmp(optarg, "stop") == 0)
 558                                 muxclient_command = SSHMUX_COMMAND_STOP;
 559                         else if (strcmp(optarg, "cancel") == 0)
 560                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
 561                         else
 562                                 fatal("Invalid multiplex command.");
 563                         break;
 564                 case 'P':       /* deprecated */
 565                         options.use_privileged_port = 0;
 566                         break;
 567                 case 'Q':
 568                         cp = NULL;
 569                         if (strcmp(optarg, "cipher") == 0)
 570                                 cp = cipher_alg_list('\n', 0);
 571                         else if (strcmp(optarg, "cipher-auth") == 0)
 572                                 cp = cipher_alg_list('\n', 1);
 573                         else if (strcmp(optarg, "mac") == 0)
 574                                 cp = mac_alg_list('\n');
 575                         else if (strcmp(optarg, "kex") == 0)
 576                                 cp = kex_alg_list('\n');
 577                         else if (strcmp(optarg, "key") == 0)
 578                                 cp = key_alg_list(0, 0);
 579                         else if (strcmp(optarg, "key-cert") == 0)
 580                                 cp = key_alg_list(1, 0);
 581                         else if (strcmp(optarg, "key-plain") == 0)
 582                                 cp = key_alg_list(0, 1);
 583                         if (cp == NULL)
 584                                 fatal("Unsupported query \"%s\"", optarg);
 585                         printf("%s\n", cp);
 586                         free(cp);
 587                         exit(0);
 588                         break;
 589                 case 'a':
 590                         options.forward_agent = 0;
 591                         break;
 592                 case 'A':
 593                         options.forward_agent = 1;
 594                         break;
 595                 case 'k':
 596                         options.gss_deleg_creds = 0;
 597                         break;
 598                 case 'K':
 599                         options.gss_authentication = 1;
 600                         options.gss_deleg_creds = 1;
 601                         break;
 602                 case 'i':
 603                         if (stat(optarg, &st) < 0) {
 604                                 fprintf(stderr, "Warning: Identity file %s "
 605                                     "not accessible: %s.\n", optarg,
 606                                     strerror(errno));
 607                                 break;
 608                         }
 609                         add_identity_file(&options, NULL, optarg, 1);
 610                         break;
 611                 case 'I':
 612 #ifdef ENABLE_PKCS11
 613                         options.pkcs11_provider = xstrdup(optarg);
 614 #else
 615                         fprintf(stderr, "no support for PKCS#11.\n");
 616 #endif
 617                         break;
 618                 case 't':
 619                         if (options.request_tty == REQUEST_TTY_YES)
 620                                 options.request_tty = REQUEST_TTY_FORCE;
 621                         else
 622                                 options.request_tty = REQUEST_TTY_YES;
 623                         break;
 624                 case 'v':
 625                         if (debug_flag == 0) {
 626                                 debug_flag = 1;
 627                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
 628                         } else {
 629                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
 630                                         options.log_level++;
 631                         }
 632                         break;
 633                 case 'V':
 634                         if (options.version_addendum &&
 635                             *options.version_addendum != '\0')
 636                                 fprintf(stderr, "%s%s %s, %s\n", SSH_RELEASE,
 637                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 638                                     options.version_addendum,
 639                                     SSLeay_version(SSLEAY_VERSION));
 640                         else
 641                                 fprintf(stderr, "%s%s, %s\n", SSH_RELEASE,
 642                                     options.hpn_disabled ? "" : SSH_VERSION_HPN,
 643                                     SSLeay_version(SSLEAY_VERSION));
 644                         if (opt == 'V')
 645                                 exit(0);
 646                         break;
 647                 case 'w':
 648                         if (options.tun_open == -1)
 649                                 options.tun_open = SSH_TUNMODE_DEFAULT;
 650                         options.tun_local = a2tun(optarg, &options.tun_remote);
 651                         if (options.tun_local == SSH_TUNID_ERR) {
 652                                 fprintf(stderr,
 653                                     "Bad tun device '%s'\n", optarg);
 654                                 exit(255);
 655                         }
 656                         break;
 657                 case 'W':
 658                         if (stdio_forward_host != NULL)
 659                                 fatal("stdio forward already specified");
 660                         if (muxclient_command != 0)
 661                                 fatal("Cannot specify stdio forward with -O");
 662                         if (parse_forward(&fwd, optarg, 1, 0)) {
 663                                 stdio_forward_host = fwd.listen_host;
 664                                 stdio_forward_port = fwd.listen_port;
 665                                 free(fwd.connect_host);
 666                         } else {
 667                                 fprintf(stderr,
 668                                     "Bad stdio forwarding specification '%s'\n",
 669                                     optarg);
 670                                 exit(255);
 671                         }
 672                         options.request_tty = REQUEST_TTY_NO;
 673                         no_shell_flag = 1;
 674                         options.clear_forwardings = 1;
 675                         options.exit_on_forward_failure = 1;
 676                         break;
 677                 case 'q':
 678                         options.log_level = SYSLOG_LEVEL_QUIET;
 679                         break;
 680                 case 'e':
 681                         if (optarg[0] == '^' && optarg[2] == 0 &&
 682                             (u_char) optarg[1] >= 64 &&
 683                             (u_char) optarg[1] < 128)
 684                                 options.escape_char = (u_char) optarg[1] & 31;
 685                         else if (strlen(optarg) == 1)
 686                                 options.escape_char = (u_char) optarg[0];
 687                         else if (strcmp(optarg, "none") == 0)
 688                                 options.escape_char = SSH_ESCAPECHAR_NONE;
 689                         else {
 690                                 fprintf(stderr, "Bad escape character '%s'.\n",
 691                                     optarg);
 692                                 exit(255);
 693                         }
 694                         break;
 695                 case 'c':
 696                         if (ciphers_valid(optarg)) {
 697                                 /* SSH2 only */
 698                                 options.ciphers = xstrdup(optarg);
 699                                 options.cipher = SSH_CIPHER_INVALID;
 700                         } else {
 701                                 /* SSH1 only */
 702                                 options.cipher = cipher_number(optarg);
 703                                 if (options.cipher == -1) {
 704                                         fprintf(stderr,
 705                                             "Unknown cipher type '%s'\n",
 706                                             optarg);
 707                                         exit(255);
 708                                 }
 709                                 if (options.cipher == SSH_CIPHER_3DES)
 710                                         options.ciphers = "3des-cbc";
 711                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
 712                                         options.ciphers = "blowfish-cbc";
 713                                 else
 714                                         options.ciphers = (char *)-1;
 715                         }
 716                         break;
 717                 case 'm':
 718                         if (mac_valid(optarg))
 719                                 options.macs = xstrdup(optarg);
 720                         else {
 721                                 fprintf(stderr, "Unknown mac type '%s'\n",
 722                                     optarg);
 723                                 exit(255);
 724                         }
 725                         break;
 726                 case 'M':
 727                         if (options.control_master == SSHCTL_MASTER_YES)
 728                                 options.control_master = SSHCTL_MASTER_ASK;
 729                         else
 730                                 options.control_master = SSHCTL_MASTER_YES;
 731                         break;
 732                 case 'p':
 733                         options.port = a2port(optarg);
 734                         if (options.port <= 0) {
 735                                 fprintf(stderr, "Bad port '%s'\n", optarg);
 736                                 exit(255);
 737                         }
 738                         break;
 739                 case 'l':
 740                         options.user = optarg;
 741                         break;
 742
 743                 case 'L':
 744                         if (parse_forward(&fwd, optarg, 0, 0))
 745                                 add_local_forward(&options, &fwd);
 746                         else {
 747                                 fprintf(stderr,
 748                                     "Bad local forwarding specification '%s'\n",
 749                                     optarg);
 750                                 exit(255);
 751                         }
 752                         break;
 753
 754                 case 'R':
 755                         if (parse_forward(&fwd, optarg, 0, 1)) {
 756                                 add_remote_forward(&options, &fwd);
 757                         } else {
 758                                 fprintf(stderr,
 759                                     "Bad remote forwarding specification "
 760                                     "'%s'\n", optarg);
 761                                 exit(255);
 762                         }
 763                         break;
 764
 765                 case 'D':
 766                         if (parse_forward(&fwd, optarg, 1, 0)) {
 767                                 add_local_forward(&options, &fwd);
 768                         } else {
 769                                 fprintf(stderr,
 770                                     "Bad dynamic forwarding specification "
 771                                     "'%s'\n", optarg);
 772                                 exit(255);
 773                         }
 774                         break;
 775
 776                 case 'C':
 777                         options.compression = 1;
 778                         break;
 779                 case 'N':
 780                         no_shell_flag = 1;
 781                         options.request_tty = REQUEST_TTY_NO;
 782                         break;
 783                 case 'T':
 784                         options.request_tty = REQUEST_TTY_NO;
 785 #ifdef  NONE_CIPHER_ENABLED
 786                         /*
 787                          * Ensure that the user does not try to backdoor a
 788                          * NONE cipher switch on an interactive session by
 789                          * explicitly disabling it if the user asks for a
 790                          * session without a tty.
 791                          */
 792                         options.none_switch = 0;
 793 #endif
 794                         break;
 795                 case 'o':
 796                         line = xstrdup(optarg);
 797                         if (process_config_line(&options, pw, host ? host : "",
 798                             line, "command-line", 0, NULL, SSHCONF_USERCONF)
 799                             != 0)
 800                                 exit(255);
 801                         free(line);
 802                         break;
 803                 case 's':
 804                         subsystem_flag = 1;
 805                         break;
 806                 case 'S':
 807                         if (options.control_path != NULL)
 808                                 free(options.control_path);
 809                         options.control_path = xstrdup(optarg);
 810                         break;
 811                 case 'b':
 812                         options.bind_address = optarg;
 813                         break;
 814                 case 'F':
 815                         config = optarg;
 816                         break;
 817                 default:
 818                         usage();
 819                 }
 820         }
 821
 822         ac -= optind;
 823         av += optind;
 824
 825         if (ac > 0 && !host) {
 826                 if (strrchr(*av, '@')) {
 827                         p = xstrdup(*av);
 828                         cp = strrchr(p, '@');
 829                         if (cp == NULL || cp == p)
 830                                 usage();
 831                         options.user = p;
 832                         *cp = '\0';
 833                         host = xstrdup(++cp);
 834                 } else
 835                         host = xstrdup(*av);
 836                 if (ac > 1) {
 837                         optind = optreset = 1;
 838                         goto again;
 839                 }
 840                 ac--, av++;
 841         }
 842
 843         /* Check that we got a host name. */
 844         if (!host)
 845                 usage();
 846
 847         host_arg = xstrdup(host);
 848
 849         OpenSSL_add_all_algorithms();
 850         ERR_load_crypto_strings();
 851
 852         /* Initialize the command to execute on remote host. */
 853         buffer_init(&command);
 854
 855         /*
 856          * Save the command to execute on the remote host in a buffer. There
 857          * is no limit on the length of the command, except by the maximum
 858          * packet size.  Also sets the tty flag if there is no command.
 859          */
 860         if (!ac) {
 861                 /* No command specified - execute shell on a tty. */
 862                 if (subsystem_flag) {
 863                         fprintf(stderr,
 864                             "You must specify a subsystem to invoke.\n");
 865                         usage();
 866                 }
 867         } else {
 868                 /* A command has been specified.  Store it into the buffer. */
 869                 for (i = 0; i < ac; i++) {
 870                         if (i)
 871                                 buffer_append(&command, " ", 1);
 872                         buffer_append(&command, av[i], strlen(av[i]));
 873                 }
 874         }
 875
 876         /* Cannot fork to background if no command. */
 877         if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
 878             !no_shell_flag)
 879                 fatal("Cannot fork into background without a command "
 880                     "to execute.");
 881
 882         /*
 883          * Initialize "log" output.  Since we are the client all output
 884          * goes to stderr unless otherwise specified by -y or -E.
 885          */
 886         if (use_syslog && logfile != NULL)
 887                 fatal("Can't specify both -y and -E");
 888         if (logfile != NULL) {
 889                 log_redirect_stderr_to(logfile);
 890                 free(logfile);
 891         }
 892         log_init(argv0,
 893             options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
 894             SYSLOG_FACILITY_USER, !use_syslog);
 895
 896         if (debug_flag)
 897                 logit("%s, %s", SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
 898
 899         /* Parse the configuration files */
 900         process_config_files(pw);
 901
 902         /* Hostname canonicalisation needs a few options filled. */
 903         fill_default_options_for_canonicalization(&options);
 904
 905         /* If the user has replaced the hostname then take it into use now */
 906         if (options.hostname != NULL) {
 907                 /* NB. Please keep in sync with readconf.c:match_cfg_line() */
 908                 cp = percent_expand(options.hostname,
 909                     "h", host, (char *)NULL);
 910                 free(host);
 911                 host = cp;
 912         }
 913
 914         /* If canonicalization requested then try to apply it */
 915         lowercase(host);
 916         if (options.canonicalize_hostname != SSH_CANONICALISE_NO)
 917                 addrs = resolve_canonicalize(&host, options.port);
 918
 919         /*
 920          * If CanonicalizePermittedCNAMEs have been specified but
 921          * other canonicalization did not happen (by not being requested
 922          * or by failing with fallback) then the hostname may still be changed
 923          * as a result of CNAME following.
 924          *
 925          * Try to resolve the bare hostname name using the system resolver's
 926          * usual search rules and then apply the CNAME follow rules.
 927          *
 928          * Skip the lookup if a ProxyCommand is being used unless the user
 929          * has specifically requested canonicalisation for this case via
 930          * CanonicalizeHostname=always
 931          */
 932         if (addrs == NULL && options.num_permitted_cnames != 0 &&
 933             (option_clear_or_none(options.proxy_command) ||
 934             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
 935                 if ((addrs = resolve_host(host, options.port, 1,
 936                     cname, sizeof(cname))) == NULL)
 937                         cleanup_exit(255); /* resolve_host logs the error */
 938                 check_follow_cname(&host, cname);
 939         }
 940
 941         /*
 942          * If the target hostname has changed as a result of canonicalisation
 943          * then re-parse the configuration files as new stanzas may match.
 944          */
 945         if (strcasecmp(host_arg, host) != 0) {
 946                 debug("Hostname has changed; re-reading configuration");
 947                 process_config_files(pw);
 948         }
 949
 950         /* Fill configuration defaults. */
 951         fill_default_options(&options);
 952
 953         if (options.port == 0)
 954                 options.port = default_ssh_port();
 955         channel_set_af(options.address_family);
 956
 957         /* Tidy and check options */
 958         if (options.host_key_alias != NULL)
 959                 lowercase(options.host_key_alias);
 960         if (options.proxy_command != NULL &&
 961             strcmp(options.proxy_command, "-") == 0 &&
 962             options.proxy_use_fdpass)
 963                 fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
 964 #ifndef HAVE_CYGWIN
 965         if (original_effective_uid != 0)
 966                 options.use_privileged_port = 0;
 967 #endif
 968
 969         /* reinit */
 970         log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
 971
 972         if (options.request_tty == REQUEST_TTY_YES ||
 973             options.request_tty == REQUEST_TTY_FORCE)
 974                 tty_flag = 1;
 975
 976         /* Allocate a tty by default if no command specified. */
 977         if (buffer_len(&command) == 0)
 978                 tty_flag = options.request_tty != REQUEST_TTY_NO;
 979
 980         /* Force no tty */
 981         if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
 982                 tty_flag = 0;
 983         /* Do not allocate a tty if stdin is not a tty. */
 984         if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
 985             options.request_tty != REQUEST_TTY_FORCE) {
 986                 if (tty_flag)
 987                         logit("Pseudo-terminal will not be allocated because "
 988                             "stdin is not a terminal.");
 989                 tty_flag = 0;
 990         }
 991
 992         seed_rng();
 993
 994         if (options.user == NULL)
 995                 options.user = xstrdup(pw->pw_name);
 996
 997         if (gethostname(thishost, sizeof(thishost)) == -1)
 998                 fatal("gethostname: %s", strerror(errno));
 999         strlcpy(shorthost, thishost, sizeof(shorthost));
1000         shorthost[strcspn(thishost, ".")] = '\0';
1001         snprintf(portstr, sizeof(portstr), "%d", options.port);
1002
1003         /* Find canonic host name. */
1004         if (strchr(host, '.') == 0) {
1005                 struct addrinfo hints;
1006                 struct addrinfo *ai = NULL;
1007                 int errgai;
1008                 memset(&hints, 0, sizeof(hints));
1009                 hints.ai_family = options.address_family;
1010                 hints.ai_flags = AI_CANONNAME;
1011                 hints.ai_socktype = SOCK_STREAM;
1012                 errgai = getaddrinfo(host, NULL, &hints, &ai);
1013                 if (errgai == 0) {
1014                         if (ai->ai_canonname != NULL)
1015                                 host = xstrdup(ai->ai_canonname);
1016                         freeaddrinfo(ai);
1017                 }
1018         }
1019
1020         if (options.local_command != NULL) {
1021                 debug3("expanding LocalCommand: %s", options.local_command);
1022                 cp = options.local_command;
1023                 options.local_command = percent_expand(cp, "d", pw->pw_dir,
1024                     "h", host, "l", thishost, "n", host_arg, "r", options.user,
1025                     "p", portstr, "u", pw->pw_name, "L", shorthost,
1026                     (char *)NULL);
1027                 debug3("expanded LocalCommand: %s", options.local_command);
1028                 free(cp);
1029         }
1030
1031         if (options.control_path != NULL) {
1032                 cp = tilde_expand_filename(options.control_path,
1033                     original_real_uid);
1034                 free(options.control_path);
1035                 options.control_path = percent_expand(cp, "h", host,
1036                     "l", thishost, "n", host_arg, "r", options.user,
1037                     "p", portstr, "u", pw->pw_name, "L", shorthost,
1038                     (char *)NULL);
1039                 free(cp);
1040         }
1041         if (muxclient_command != 0 && options.control_path == NULL)
1042                 fatal("No ControlPath specified for \"-O\" command");
1043         if (options.control_path != NULL)
1044                 muxclient(options.control_path);
1045
1046         /*
1047          * If hostname canonicalisation was not enabled, then we may not
1048          * have yet resolved the hostname. Do so now.
1049          */
1050         if (addrs == NULL && options.proxy_command == NULL) {
1051                 if ((addrs = resolve_host(host, options.port, 1,
1052                     cname, sizeof(cname))) == NULL)
1053                         cleanup_exit(255); /* resolve_host logs the error */
1054         }
1055
1056         timeout_ms = options.connection_timeout * 1000;
1057
1058         /* Open a connection to the remote host. */
1059         if (ssh_connect(host, addrs, &hostaddr, options.port,
1060             options.address_family, options.connection_attempts,
1061             &timeout_ms, options.tcp_keep_alive,
1062             options.use_privileged_port) != 0)
1063                 exit(255);
1064
1065         if (addrs != NULL)
1066                 freeaddrinfo(addrs);
1067
1068         packet_set_timeout(options.server_alive_interval,
1069             options.server_alive_count_max);
1070
1071         if (timeout_ms > 0)
1072                 debug3("timeout: %d ms remain after connect", timeout_ms);
1073
1074         /*
1075          * If we successfully made the connection, load the host private key
1076          * in case we will need it later for combined rsa-rhosts
1077          * authentication. This must be done before releasing extra
1078          * privileges, because the file is only readable by root.
1079          * If we cannot access the private keys, load the public keys
1080          * instead and try to execute the ssh-keysign helper instead.
1081          */
1082         sensitive_data.nkeys = 0;
1083         sensitive_data.keys = NULL;
1084         sensitive_data.external_keysign = 0;
1085         if (options.rhosts_rsa_authentication ||
1086             options.hostbased_authentication) {
1087                 sensitive_data.nkeys = 9;
1088                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1089                     sizeof(Key));
1090                 for (i = 0; i < sensitive_data.nkeys; i++)
1091                         sensitive_data.keys[i] = NULL;
1092
1093                 PRIV_START;
1094                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
1095                     _PATH_HOST_KEY_FILE, "", NULL, NULL);
1096                 sensitive_data.keys[1] = key_load_private_cert(KEY_DSA,
1097                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
1098 #ifdef OPENSSL_HAS_ECC
1099                 sensitive_data.keys[2] = key_load_private_cert(KEY_ECDSA,
1100                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
1101 #endif
1102                 sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
1103                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
1104                 sensitive_data.keys[4] = key_load_private_cert(KEY_ED25519,
1105                     _PATH_HOST_ED25519_KEY_FILE, "", NULL);
1106                 sensitive_data.keys[5] = key_load_private_type(KEY_DSA,
1107                     _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
1108 #ifdef OPENSSL_HAS_ECC
1109                 sensitive_data.keys[6] = key_load_private_type(KEY_ECDSA,
1110                     _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
1111 #endif
1112                 sensitive_data.keys[7] = key_load_private_type(KEY_RSA,
1113                     _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
1114                 sensitive_data.keys[8] = key_load_private_type(KEY_ED25519,
1115                     _PATH_HOST_ED25519_KEY_FILE, "", NULL, NULL);
1116                 PRIV_END;
1117
1118                 if (options.hostbased_authentication == 1 &&
1119                     sensitive_data.keys[0] == NULL &&
1120                     sensitive_data.keys[5] == NULL &&
1121                     sensitive_data.keys[6] == NULL &&
1122                     sensitive_data.keys[7] == NULL &&
1123                     sensitive_data.keys[8] == NULL) {
1124                         sensitive_data.keys[1] = key_load_cert(
1125                             _PATH_HOST_DSA_KEY_FILE);
1126 #ifdef OPENSSL_HAS_ECC
1127                         sensitive_data.keys[2] = key_load_cert(
1128                             _PATH_HOST_ECDSA_KEY_FILE);
1129 #endif
1130                         sensitive_data.keys[3] = key_load_cert(
1131                             _PATH_HOST_RSA_KEY_FILE);
1132                         sensitive_data.keys[4] = key_load_cert(
1133                             _PATH_HOST_ED25519_KEY_FILE);
1134                         sensitive_data.keys[5] = key_load_public(
1135                             _PATH_HOST_DSA_KEY_FILE, NULL);
1136 #ifdef OPENSSL_HAS_ECC
1137                         sensitive_data.keys[6] = key_load_public(
1138                             _PATH_HOST_ECDSA_KEY_FILE, NULL);
1139 #endif
1140                         sensitive_data.keys[7] = key_load_public(
1141                             _PATH_HOST_RSA_KEY_FILE, NULL);
1142                         sensitive_data.keys[8] = key_load_public(
1143                             _PATH_HOST_ED25519_KEY_FILE, NULL);
1144                         sensitive_data.external_keysign = 1;
1145                 }
1146         }
1147         /*
1148          * Get rid of any extra privileges that we may have.  We will no
1149          * longer need them.  Also, extra privileges could make it very hard
1150          * to read identity files and other non-world-readable files from the
1151          * user's home directory if it happens to be on a NFS volume where
1152          * root is mapped to nobody.
1153          */
1154         if (original_effective_uid == 0) {
1155                 PRIV_START;
1156                 permanently_set_uid(pw);
1157         }
1158
1159         /*
1160          * Now that we are back to our own permissions, create ~/.ssh
1161          * directory if it doesn't already exist.
1162          */
1163         if (config == NULL) {
1164                 r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1165                     strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1166                 if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
1167 #ifdef WITH_SELINUX
1168                         ssh_selinux_setfscreatecon(buf);
1169 #endif
1170                         if (mkdir(buf, 0700) < 0)
1171                                 error("Could not create directory '%.200s'.",
1172                                     buf);
1173 #ifdef WITH_SELINUX
1174                         ssh_selinux_setfscreatecon(NULL);
1175 #endif
1176                 }
1177         }
1178         /* load options.identity_files */
1179         load_public_identity_files();
1180
1181         /* Expand ~ in known host file names. */
1182         tilde_expand_paths(options.system_hostfiles,
1183             options.num_system_hostfiles);
1184         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1185
1186         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1187         signal(SIGCHLD, main_sigchld_handler);
1188
1189         /* Log into the remote system.  Never returns if the login fails. */
1190         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1191             options.port, pw, timeout_ms);
1192
1193         if (packet_connection_is_on_socket()) {
1194                 verbose("Authenticated to %s ([%s]:%d).", host,
1195                     get_remote_ipaddr(), get_remote_port());
1196         } else {
1197                 verbose("Authenticated to %s (via proxy).", host);
1198         }
1199
1200         /* We no longer need the private host keys.  Clear them now. */
1201         if (sensitive_data.nkeys != 0) {
1202                 for (i = 0; i < sensitive_data.nkeys; i++) {
1203                         if (sensitive_data.keys[i] != NULL) {
1204                                 /* Destroys contents safely */
1205                                 debug3("clear hostkey %d", i);
1206                                 key_free(sensitive_data.keys[i]);
1207                                 sensitive_data.keys[i] = NULL;
1208                         }
1209                 }
1210                 free(sensitive_data.keys);
1211         }
1212         for (i = 0; i < options.num_identity_files; i++) {
1213                 free(options.identity_files[i]);
1214                 options.identity_files[i] = NULL;
1215                 if (options.identity_keys[i]) {
1216                         key_free(options.identity_keys[i]);
1217                         options.identity_keys[i] = NULL;
1218                 }
1219         }
1220
1221         exit_status = compat20 ? ssh_session2() : ssh_session();
1222         packet_close();
1223
1224         if (options.control_path != NULL && muxserver_sock != -1)
1225                 unlink(options.control_path);
1226
1227         /* Kill ProxyCommand if it is running. */
1228         ssh_kill_proxy_command();
1229
1230         return exit_status;
1231 }
1232
1233 static void
1234 control_persist_detach(void)
1235 {
1236         pid_t pid;
1237         int devnull;
1238
1239         debug("%s: backgrounding master process", __func__);
1240
1241         /*
1242          * master (current process) into the background, and make the
1243          * foreground process a client of the backgrounded master.
1244          */
1245         switch ((pid = fork())) {
1246         case -1:
1247                 fatal("%s: fork: %s", __func__, strerror(errno));
1248         case 0:
1249                 /* Child: master process continues mainloop */
1250                 break;
1251         default:
1252                 /* Parent: set up mux slave to connect to backgrounded master */
1253                 debug2("%s: background process is %ld", __func__, (long)pid);
1254                 stdin_null_flag = ostdin_null_flag;
1255                 options.request_tty = orequest_tty;
1256                 tty_flag = otty_flag;
1257                 close(muxserver_sock);
1258                 muxserver_sock = -1;
1259                 options.control_master = SSHCTL_MASTER_NO;
1260                 muxclient(options.control_path);
1261                 /* muxclient() doesn't return on success. */
1262                 fatal("Failed to connect to new control master");
1263         }
1264         if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1265                 error("%s: open(\"/dev/null\"): %s", __func__,
1266                     strerror(errno));
1267         } else {
1268                 if (dup2(devnull, STDIN_FILENO) == -1 ||
1269                     dup2(devnull, STDOUT_FILENO) == -1)
1270                         error("%s: dup2: %s", __func__, strerror(errno));
1271                 if (devnull > STDERR_FILENO)
1272                         close(devnull);
1273         }
1274         daemon(1, 1);
1275         setproctitle("%s [mux]", options.control_path);
1276 }
1277
1278 /* Do fork() after authentication. Used by "ssh -f" */
1279 static void
1280 fork_postauth(void)
1281 {
1282         if (need_controlpersist_detach)
1283                 control_persist_detach();
1284         debug("forking to background");
1285         fork_after_authentication_flag = 0;
1286         if (daemon(1, 1) < 0)
1287                 fatal("daemon() failed: %.200s", strerror(errno));
1288 }
1289
1290 /* Callback for remote forward global requests */
1291 static void
1292 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1293 {
1294         Forward *rfwd = (Forward *)ctxt;
1295
1296         /* XXX verbose() on failure? */
1297         debug("remote forward %s for: listen %d, connect %s:%d",
1298             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1299             rfwd->listen_port, rfwd->connect_host, rfwd->connect_port);
1300         if (rfwd->listen_port == 0) {
1301                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1302                         rfwd->allocated_port = packet_get_int();
1303                         logit("Allocated port %u for remote forward to %s:%d",
1304                             rfwd->allocated_port,
1305                             rfwd->connect_host, rfwd->connect_port);
1306                         channel_update_permitted_opens(rfwd->handle,
1307                             rfwd->allocated_port);
1308                 } else {
1309                         channel_update_permitted_opens(rfwd->handle, -1);
1310                 }
1311         }
1312
1313         if (type == SSH2_MSG_REQUEST_FAILURE) {
1314                 if (options.exit_on_forward_failure)
1315                         fatal("Error: remote port forwarding failed for "
1316                             "listen port %d", rfwd->listen_port);
1317                 else
1318                         logit("Warning: remote port forwarding failed for "
1319                             "listen port %d", rfwd->listen_port);
1320         }
1321         if (++remote_forward_confirms_received == options.num_remote_forwards) {
1322                 debug("All remote forwarding requests processed");
1323                 if (fork_after_authentication_flag)
1324                         fork_postauth();
1325         }
1326 }
1327
1328 static void
1329 client_cleanup_stdio_fwd(int id, void *arg)
1330 {
1331         debug("stdio forwarding: done");
1332         cleanup_exit(0);
1333 }
1334
1335 static void
1336 ssh_init_stdio_forwarding(void)
1337 {
1338         Channel *c;
1339         int in, out;
1340
1341         if (stdio_forward_host == NULL)
1342                 return;
1343         if (!compat20)
1344                 fatal("stdio forwarding require Protocol 2");
1345
1346         debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1347
1348         if ((in = dup(STDIN_FILENO)) < 0 ||
1349             (out = dup(STDOUT_FILENO)) < 0)
1350                 fatal("channel_connect_stdio_fwd: dup() in/out failed");
1351         if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1352             stdio_forward_port, in, out)) == NULL)
1353                 fatal("%s: channel_connect_stdio_fwd failed", __func__);
1354         channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1355 }
1356
1357 static void
1358 ssh_init_forwarding(void)
1359 {
1360         int success = 0;
1361         int i;
1362
1363         /* Initiate local TCP/IP port forwardings. */
1364         for (i = 0; i < options.num_local_forwards; i++) {
1365                 debug("Local connections to %.200s:%d forwarded to remote "
1366                     "address %.200s:%d",
1367                     (options.local_forwards[i].listen_host == NULL) ?
1368                     (options.gateway_ports ? "*" : "LOCALHOST") :
1369                     options.local_forwards[i].listen_host,
1370                     options.local_forwards[i].listen_port,
1371                     options.local_forwards[i].connect_host,
1372                     options.local_forwards[i].connect_port);
1373                 success += channel_setup_local_fwd_listener(
1374                     options.local_forwards[i].listen_host,
1375                     options.local_forwards[i].listen_port,
1376                     options.local_forwards[i].connect_host,
1377                     options.local_forwards[i].connect_port,
1378                     options.gateway_ports);
1379         }
1380         if (i > 0 && success != i && options.exit_on_forward_failure)
1381                 fatal("Could not request local forwarding.");
1382         if (i > 0 && success == 0)
1383                 error("Could not request local forwarding.");
1384
1385         /* Initiate remote TCP/IP port forwardings. */
1386         for (i = 0; i < options.num_remote_forwards; i++) {
1387                 debug("Remote connections from %.200s:%d forwarded to "
1388                     "local address %.200s:%d",
1389                     (options.remote_forwards[i].listen_host == NULL) ?
1390                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1391                     options.remote_forwards[i].listen_port,
1392                     options.remote_forwards[i].connect_host,
1393                     options.remote_forwards[i].connect_port);
1394                 options.remote_forwards[i].handle =
1395                     channel_request_remote_forwarding(
1396                     options.remote_forwards[i].listen_host,
1397                     options.remote_forwards[i].listen_port,
1398                     options.remote_forwards[i].connect_host,
1399                     options.remote_forwards[i].connect_port);
1400                 if (options.remote_forwards[i].handle < 0) {
1401                         if (options.exit_on_forward_failure)
1402                                 fatal("Could not request remote forwarding.");
1403                         else
1404                                 logit("Warning: Could not request remote "
1405                                     "forwarding.");
1406                 } else {
1407                         client_register_global_confirm(ssh_confirm_remote_forward,
1408                             &options.remote_forwards[i]);
1409                 }
1410         }
1411
1412         /* Initiate tunnel forwarding. */
1413         if (options.tun_open != SSH_TUNMODE_NO) {
1414                 if (client_request_tun_fwd(options.tun_open,
1415                     options.tun_local, options.tun_remote) == -1) {
1416                         if (options.exit_on_forward_failure)
1417                                 fatal("Could not request tunnel forwarding.");
1418                         else
1419                                 error("Could not request tunnel forwarding.");
1420                 }
1421         }
1422 }
1423
1424 static void
1425 check_agent_present(void)
1426 {
1427         if (options.forward_agent) {
1428                 /* Clear agent forwarding if we don't have an agent. */
1429                 if (!ssh_agent_present())
1430                         options.forward_agent = 0;
1431         }
1432 }
1433
1434 static int
1435 ssh_session(void)
1436 {
1437         int type;
1438         int interactive = 0;
1439         int have_tty = 0;
1440         struct winsize ws;
1441         char *cp;
1442         const char *display;
1443
1444         /* Enable compression if requested. */
1445         if (options.compression) {
1446                 debug("Requesting compression at level %d.",
1447                     options.compression_level);
1448
1449                 if (options.compression_level < 1 ||
1450                     options.compression_level > 9)
1451                         fatal("Compression level must be from 1 (fast) to "
1452                             "9 (slow, best).");
1453
1454                 /* Send the request. */
1455                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1456                 packet_put_int(options.compression_level);
1457                 packet_send();
1458                 packet_write_wait();
1459                 type = packet_read();
1460                 if (type == SSH_SMSG_SUCCESS)
1461                         packet_start_compression(options.compression_level);
1462                 else if (type == SSH_SMSG_FAILURE)
1463                         logit("Warning: Remote host refused compression.");
1464                 else
1465                         packet_disconnect("Protocol error waiting for "
1466                             "compression response.");
1467         }
1468         /* Allocate a pseudo tty if appropriate. */
1469         if (tty_flag) {
1470                 debug("Requesting pty.");
1471
1472                 /* Start the packet. */
1473                 packet_start(SSH_CMSG_REQUEST_PTY);
1474
1475                 /* Store TERM in the packet.  There is no limit on the
1476                    length of the string. */
1477                 cp = getenv("TERM");
1478                 if (!cp)
1479                         cp = "";
1480                 packet_put_cstring(cp);
1481
1482                 /* Store window size in the packet. */
1483                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1484                         memset(&ws, 0, sizeof(ws));
1485                 packet_put_int((u_int)ws.ws_row);
1486                 packet_put_int((u_int)ws.ws_col);
1487                 packet_put_int((u_int)ws.ws_xpixel);
1488                 packet_put_int((u_int)ws.ws_ypixel);
1489
1490                 /* Store tty modes in the packet. */
1491                 tty_make_modes(fileno(stdin), NULL);
1492
1493                 /* Send the packet, and wait for it to leave. */
1494                 packet_send();
1495                 packet_write_wait();
1496
1497                 /* Read response from the server. */
1498                 type = packet_read();
1499                 if (type == SSH_SMSG_SUCCESS) {
1500                         interactive = 1;
1501                         have_tty = 1;
1502                 } else if (type == SSH_SMSG_FAILURE)
1503                         logit("Warning: Remote host failed or refused to "
1504                             "allocate a pseudo tty.");
1505                 else
1506                         packet_disconnect("Protocol error waiting for pty "
1507                             "request response.");
1508         }
1509         /* Request X11 forwarding if enabled and DISPLAY is set. */
1510         display = getenv("DISPLAY");
1511         if (options.forward_x11 && display != NULL) {
1512                 char *proto, *data;
1513                 /* Get reasonable local authentication information. */
1514                 client_x11_get_proto(display, options.xauth_location,
1515                     options.forward_x11_trusted,
1516                     options.forward_x11_timeout,
1517                     &proto, &data);
1518                 /* Request forwarding with authentication spoofing. */
1519                 debug("Requesting X11 forwarding with authentication "
1520                     "spoofing.");
1521                 x11_request_forwarding_with_spoofing(0, display, proto,
1522                     data, 0);
1523                 /* Read response from the server. */
1524                 type = packet_read();
1525                 if (type == SSH_SMSG_SUCCESS) {
1526                         interactive = 1;
1527                 } else if (type == SSH_SMSG_FAILURE) {
1528                         logit("Warning: Remote host denied X11 forwarding.");
1529                 } else {
1530                         packet_disconnect("Protocol error waiting for X11 "
1531                             "forwarding");
1532                 }
1533         }
1534         /* Tell the packet module whether this is an interactive session. */
1535         packet_set_interactive(interactive,
1536             options.ip_qos_interactive, options.ip_qos_bulk);
1537
1538         /* Request authentication agent forwarding if appropriate. */
1539         check_agent_present();
1540
1541         if (options.forward_agent) {
1542                 debug("Requesting authentication agent forwarding.");
1543                 auth_request_forwarding();
1544
1545                 /* Read response from the server. */
1546                 type = packet_read();
1547                 packet_check_eom();
1548                 if (type != SSH_SMSG_SUCCESS)
1549                         logit("Warning: Remote host denied authentication agent forwarding.");
1550         }
1551
1552         /* Initiate port forwardings. */
1553         ssh_init_stdio_forwarding();
1554         ssh_init_forwarding();
1555
1556         /* Execute a local command */
1557         if (options.local_command != NULL &&
1558             options.permit_local_command)
1559                 ssh_local_cmd(options.local_command);
1560
1561         /*
1562          * If requested and we are not interested in replies to remote
1563          * forwarding requests, then let ssh continue in the background.
1564          */
1565         if (fork_after_authentication_flag) {
1566                 if (options.exit_on_forward_failure &&
1567                     options.num_remote_forwards > 0) {
1568                         debug("deferring postauth fork until remote forward "
1569                             "confirmation received");
1570                 } else
1571                         fork_postauth();
1572         }
1573
1574         /*
1575          * If a command was specified on the command line, execute the
1576          * command now. Otherwise request the server to start a shell.
1577          */
1578         if (buffer_len(&command) > 0) {
1579                 int len = buffer_len(&command);
1580                 if (len > 900)
1581                         len = 900;
1582                 debug("Sending command: %.*s", len,
1583                     (u_char *)buffer_ptr(&command));
1584                 packet_start(SSH_CMSG_EXEC_CMD);
1585                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1586                 packet_send();
1587                 packet_write_wait();
1588         } else {
1589                 debug("Requesting shell.");
1590                 packet_start(SSH_CMSG_EXEC_SHELL);
1591                 packet_send();
1592                 packet_write_wait();
1593         }
1594
1595         /* Enter the interactive session. */
1596         return client_loop(have_tty, tty_flag ?
1597             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1598 }
1599
1600 /* request pty/x11/agent/tcpfwd/shell for channel */
1601 static void
1602 ssh_session2_setup(int id, int success, void *arg)
1603 {
1604         extern char **environ;
1605         const char *display;
1606         int interactive = tty_flag;
1607
1608         if (!success)
1609                 return; /* No need for error message, channels code sens one */
1610
1611         display = getenv("DISPLAY");
1612         if (options.forward_x11 && display != NULL) {
1613                 char *proto, *data;
1614                 /* Get reasonable local authentication information. */
1615                 client_x11_get_proto(display, options.xauth_location,
1616                     options.forward_x11_trusted,
1617                     options.forward_x11_timeout, &proto, &data);
1618                 /* Request forwarding with authentication spoofing. */
1619                 debug("Requesting X11 forwarding with authentication "
1620                     "spoofing.");
1621                 x11_request_forwarding_with_spoofing(id, display, proto,
1622                     data, 1);
1623                 client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1624                 /* XXX exit_on_forward_failure */
1625                 interactive = 1;
1626         }
1627
1628         check_agent_present();
1629         if (options.forward_agent) {
1630                 debug("Requesting authentication agent forwarding.");
1631                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1632                 packet_send();
1633         }
1634
1635         /* Tell the packet module whether this is an interactive session. */
1636         packet_set_interactive(interactive,
1637             options.ip_qos_interactive, options.ip_qos_bulk);
1638
1639         client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1640             NULL, fileno(stdin), &command, environ);
1641 }
1642
1643 /* open new channel for a session */
1644 static int
1645 ssh_session2_open(void)
1646 {
1647         Channel *c;
1648         int window, packetmax, in, out, err;
1649
1650         if (stdin_null_flag) {
1651                 in = open(_PATH_DEVNULL, O_RDONLY);
1652         } else {
1653                 in = dup(STDIN_FILENO);
1654         }
1655         out = dup(STDOUT_FILENO);
1656         err = dup(STDERR_FILENO);
1657
1658         if (in < 0 || out < 0 || err < 0)
1659                 fatal("dup() in/out/err failed");
1660
1661         /* enable nonblocking unless tty */
1662         if (!isatty(in))
1663                 set_nonblock(in);
1664         if (!isatty(out))
1665                 set_nonblock(out);
1666         if (!isatty(err))
1667                 set_nonblock(err);
1668
1669         /*
1670          * We need to check to see what to do about buffer sizes here.
1671          * - In an HPN to non-HPN connection we want to limit the window size to
1672          *   something reasonable in case the far side has the large window bug.
1673          * - In an HPN to HPN connection we want to use the max window size but
1674          *   allow the user to override it.
1675          * - Lastly if HPN is disabled then use the ssh standard window size.
1676          *
1677          * We cannot just do a getsockopt() here and set the ssh window to that
1678          * as in case of autotuning of socket buffers the window would get stuck
1679          * at the initial buffer size, generally less than 96k.  Therefore we
1680          * need to set the maximum ssh window size to the maximum HPN buffer
1681          * size unless the user has set TcpRcvBufPoll to no.  In that case we
1682          * can just set the window to the minimum of HPN buffer size and TCP
1683          * receive buffer size.
1684          */
1685         if (tty_flag)
1686                 options.hpn_buffer_size = CHAN_SES_WINDOW_DEFAULT;
1687         else
1688                 options.hpn_buffer_size = CHAN_HPN_MIN_WINDOW_DEFAULT;
1689
1690         if (datafellows & SSH_BUG_LARGEWINDOW) {
1691                 debug("HPN to Non-HPN Connection");
1692         } else if (options.tcp_rcv_buf_poll <= 0) {
1693                 sock_get_rcvbuf(&options.hpn_buffer_size, 0);
1694                 debug("HPNBufferSize set to TCP RWIN: %d",
1695                     options.hpn_buffer_size);
1696         } else if (options.tcp_rcv_buf > 0) {
1697                 sock_get_rcvbuf(&options.hpn_buffer_size,
1698                     options.tcp_rcv_buf);
1699                 debug("HPNBufferSize set to user TCPRcvBuf: %d",
1700                     options.hpn_buffer_size);
1701         }
1702         debug("Final hpn_buffer_size = %d", options.hpn_buffer_size);
1703         channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
1704         window = options.hpn_buffer_size;
1705
1706         packetmax = CHAN_SES_PACKET_DEFAULT;
1707         if (tty_flag) {
1708                 window = CHAN_SES_WINDOW_DEFAULT;
1709                 window >>= 1;
1710                 packetmax >>= 1;
1711         }
1712         c = channel_new(
1713             "session", SSH_CHANNEL_OPENING, in, out, err,
1714             window, packetmax, CHAN_EXTENDED_WRITE,
1715             "client-session", /*nonblock*/0);
1716         if (!options.hpn_disabled && options.tcp_rcv_buf_poll > 0) {
1717                 c->dynamic_window = 1;
1718                 debug("Enabled Dynamic Window Scaling\n");
1719         }
1720
1721         debug3("ssh_session2_open: channel_new: %d", c->self);
1722
1723         channel_send_open(c->self);
1724         if (!no_shell_flag)
1725                 channel_register_open_confirm(c->self,
1726                     ssh_session2_setup, NULL);
1727
1728         return c->self;
1729 }
1730
1731 static int
1732 ssh_session2(void)
1733 {
1734         int id = -1;
1735
1736         /* XXX should be pre-session */
1737         if (!options.control_persist)
1738                 ssh_init_stdio_forwarding();
1739         ssh_init_forwarding();
1740
1741         /* Start listening for multiplex clients */
1742         muxserver_listen();
1743
1744         /*
1745          * If we are in control persist mode and have a working mux listen
1746          * socket, then prepare to background ourselves and have a foreground
1747          * client attach as a control slave.
1748          * NB. we must save copies of the flags that we override for
1749          * the backgrounding, since we defer attachment of the slave until
1750          * after the connection is fully established (in particular,
1751          * async rfwd replies have been received for ExitOnForwardFailure).
1752          */
1753         if (options.control_persist && muxserver_sock != -1) {
1754                 ostdin_null_flag = stdin_null_flag;
1755                 ono_shell_flag = no_shell_flag;
1756                 orequest_tty = options.request_tty;
1757                 otty_flag = tty_flag;
1758                 stdin_null_flag = 1;
1759                 no_shell_flag = 1;
1760                 tty_flag = 0;
1761                 if (!fork_after_authentication_flag)
1762                         need_controlpersist_detach = 1;
1763                 fork_after_authentication_flag = 1;
1764         }
1765         /*
1766          * ControlPersist mux listen socket setup failed, attempt the
1767          * stdio forward setup that we skipped earlier.
1768          */
1769         if (options.control_persist && muxserver_sock == -1)
1770                 ssh_init_stdio_forwarding();
1771
1772         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1773                 id = ssh_session2_open();
1774         else {
1775                 packet_set_interactive(
1776                     options.control_master == SSHCTL_MASTER_NO,
1777                     options.ip_qos_interactive, options.ip_qos_bulk);
1778         }
1779
1780         /* If we don't expect to open a new session, then disallow it */
1781         if (options.control_master == SSHCTL_MASTER_NO &&
1782             (datafellows & SSH_NEW_OPENSSH)) {
1783                 debug("Requesting no-more-sessions@openssh.com");
1784                 packet_start(SSH2_MSG_GLOBAL_REQUEST);
1785                 packet_put_cstring("no-more-sessions@openssh.com");
1786                 packet_put_char(0);
1787                 packet_send();
1788         }
1789
1790         /* Execute a local command */
1791         if (options.local_command != NULL &&
1792             options.permit_local_command)
1793                 ssh_local_cmd(options.local_command);
1794
1795         /*
1796          * If requested and we are not interested in replies to remote
1797          * forwarding requests, then let ssh continue in the background.
1798          */
1799         if (fork_after_authentication_flag) {
1800                 if (options.exit_on_forward_failure &&
1801                     options.num_remote_forwards > 0) {
1802                         debug("deferring postauth fork until remote forward "
1803                             "confirmation received");
1804                 } else
1805                         fork_postauth();
1806         }
1807
1808         if (options.use_roaming)
1809                 request_roaming();
1810
1811         return client_loop(tty_flag, tty_flag ?
1812             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1813 }
1814
1815 static void
1816 load_public_identity_files(void)
1817 {
1818         char *filename, *cp, thishost[NI_MAXHOST];
1819         char *pwdir = NULL, *pwname = NULL;
1820         int i = 0;
1821         Key *public;
1822         struct passwd *pw;
1823         u_int n_ids;
1824         char *identity_files[SSH_MAX_IDENTITY_FILES];
1825         Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1826 #ifdef ENABLE_PKCS11
1827         Key **keys;
1828         int nkeys;
1829 #endif /* PKCS11 */
1830
1831         n_ids = 0;
1832         memset(identity_files, 0, sizeof(identity_files));
1833         memset(identity_keys, 0, sizeof(identity_keys));
1834
1835 #ifdef ENABLE_PKCS11
1836         if (options.pkcs11_provider != NULL &&
1837             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1838             (pkcs11_init(!options.batch_mode) == 0) &&
1839             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1840             &keys)) > 0) {
1841                 for (i = 0; i < nkeys; i++) {
1842                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1843                                 key_free(keys[i]);
1844                                 continue;
1845                         }
1846                         identity_keys[n_ids] = keys[i];
1847                         identity_files[n_ids] =
1848                             xstrdup(options.pkcs11_provider); /* XXX */
1849                         n_ids++;
1850                 }
1851                 free(keys);
1852         }
1853 #endif /* ENABLE_PKCS11 */
1854         if ((pw = getpwuid(original_real_uid)) == NULL)
1855                 fatal("load_public_identity_files: getpwuid failed");
1856         pwname = xstrdup(pw->pw_name);
1857         pwdir = xstrdup(pw->pw_dir);
1858         if (gethostname(thishost, sizeof(thishost)) == -1)
1859                 fatal("load_public_identity_files: gethostname: %s",
1860                     strerror(errno));
1861         for (i = 0; i < options.num_identity_files; i++) {
1862                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1863                     strcasecmp(options.identity_files[i], "none") == 0) {
1864                         free(options.identity_files[i]);
1865                         continue;
1866                 }
1867                 cp = tilde_expand_filename(options.identity_files[i],
1868                     original_real_uid);
1869                 filename = percent_expand(cp, "d", pwdir,
1870                     "u", pwname, "l", thishost, "h", host,
1871                     "r", options.user, (char *)NULL);
1872                 free(cp);
1873                 public = key_load_public(filename, NULL);
1874                 debug("identity file %s type %d", filename,
1875                     public ? public->type : -1);
1876                 free(options.identity_files[i]);
1877                 identity_files[n_ids] = filename;
1878                 identity_keys[n_ids] = public;
1879
1880                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
1881                         continue;
1882
1883                 /* Try to add the certificate variant too */
1884                 xasprintf(&cp, "%s-cert", filename);
1885                 public = key_load_public(cp, NULL);
1886                 debug("identity file %s type %d", cp,
1887                     public ? public->type : -1);
1888                 if (public == NULL) {
1889                         free(cp);
1890                         continue;
1891                 }
1892                 if (!key_is_cert(public)) {
1893                         debug("%s: key %s type %s is not a certificate",
1894                             __func__, cp, key_type(public));
1895                         key_free(public);
1896                         free(cp);
1897                         continue;
1898                 }
1899                 identity_keys[n_ids] = public;
1900                 /* point to the original path, most likely the private key */
1901                 identity_files[n_ids] = xstrdup(filename);
1902                 n_ids++;
1903         }
1904         options.num_identity_files = n_ids;
1905         memcpy(options.identity_files, identity_files, sizeof(identity_files));
1906         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
1907
1908         explicit_bzero(pwname, strlen(pwname));
1909         free(pwname);
1910         explicit_bzero(pwdir, strlen(pwdir));
1911         free(pwdir);
1912 }
1913
1914 static void
1915 main_sigchld_handler(int sig)
1916 {
1917         int save_errno = errno;
1918         pid_t pid;
1919         int status;
1920
1921         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
1922             (pid < 0 && errno == EINTR))
1923                 ;
1924
1925         signal(sig, main_sigchld_handler);
1926         errno = save_errno;
1927 }