xref: /freebsd/crypto/openssh/ssh.c (revision 557f75e54ae47df936c7de8fb97ec70c4180a5c0)
1 /* $OpenBSD: ssh.c,v 1.418 2015/05/04 06:10:48 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 
72 #include <netinet/in.h>
73 #include <arpa/inet.h>
74 
75 #ifdef WITH_OPENSSL
76 #include <openssl/evp.h>
77 #include <openssl/err.h>
78 #endif
79 #include "openbsd-compat/openssl-compat.h"
80 #include "openbsd-compat/sys-queue.h"
81 
82 #include "xmalloc.h"
83 #include "ssh.h"
84 #include "ssh1.h"
85 #include "ssh2.h"
86 #include "canohost.h"
87 #include "compat.h"
88 #include "cipher.h"
89 #include "digest.h"
90 #include "packet.h"
91 #include "buffer.h"
92 #include "channels.h"
93 #include "key.h"
94 #include "authfd.h"
95 #include "authfile.h"
96 #include "pathnames.h"
97 #include "dispatch.h"
98 #include "clientloop.h"
99 #include "log.h"
100 #include "misc.h"
101 #include "readconf.h"
102 #include "sshconnect.h"
103 #include "kex.h"
104 #include "mac.h"
105 #include "sshpty.h"
106 #include "match.h"
107 #include "msg.h"
108 #include "uidswap.h"
109 #include "roaming.h"
110 #include "version.h"
111 #include "ssherr.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 /* forward stdio to remote host and port */
156 char *stdio_forward_host = NULL;
157 int stdio_forward_port = 0;
158 
159 /*
160  * General data structure for command line options and options configurable
161  * in configuration files.  See readconf.h.
162  */
163 Options options;
164 
165 /* optional user configfile */
166 char *config = NULL;
167 
168 /*
169  * Name of the host we are connecting to.  This is the name given on the
170  * command line, or the HostName specified for the user-supplied name in a
171  * configuration file.
172  */
173 char *host;
174 
175 /* socket address the host resolves to */
176 struct sockaddr_storage hostaddr;
177 
178 /* Private host keys. */
179 Sensitive sensitive_data;
180 
181 /* Original real UID. */
182 uid_t original_real_uid;
183 uid_t original_effective_uid;
184 
185 /* command to be executed */
186 Buffer command;
187 
188 /* Should we execute a command or invoke a subsystem? */
189 int subsystem_flag = 0;
190 
191 /* # of replies received for global requests */
192 static int remote_forward_confirms_received = 0;
193 
194 /* mux.c */
195 extern int muxserver_sock;
196 extern u_int muxclient_command;
197 
198 /* Prints a help message to the user.  This function never returns. */
199 
200 static void
201 usage(void)
202 {
203 	fprintf(stderr,
204 "usage: ssh [-1246AaCfGgKkMNnqsTtVvXxYy] [-b bind_address] [-c cipher_spec]\n"
205 "           [-D [bind_address:]port] [-E log_file] [-e escape_char]\n"
206 "           [-F configfile] [-I pkcs11] [-i identity_file]\n"
207 "           [-L [bind_address:]port:host:hostport] [-l login_name] [-m mac_spec]\n"
208 "           [-O ctl_cmd] [-o option] [-p port]\n"
209 "           [-Q cipher | cipher-auth | mac | kex | key]\n"
210 "           [-R [bind_address:]port:host:hostport] [-S ctl_path] [-W host:port]\n"
211 "           [-w local_tun[:remote_tun]] [user@]hostname [command]\n"
212 	);
213 	exit(255);
214 }
215 
216 static int ssh_session(void);
217 static int ssh_session2(void);
218 static void load_public_identity_files(void);
219 static void main_sigchld_handler(int);
220 
221 /* from muxclient.c */
222 void muxclient(const char *);
223 void muxserver_listen(void);
224 
225 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
226 static void
227 tilde_expand_paths(char **paths, u_int num_paths)
228 {
229 	u_int i;
230 	char *cp;
231 
232 	for (i = 0; i < num_paths; i++) {
233 		cp = tilde_expand_filename(paths[i], original_real_uid);
234 		free(paths[i]);
235 		paths[i] = cp;
236 	}
237 }
238 
239 /*
240  * Attempt to resolve a host name / port to a set of addresses and
241  * optionally return any CNAMEs encountered along the way.
242  * Returns NULL on failure.
243  * NB. this function must operate with a options having undefined members.
244  */
245 static struct addrinfo *
246 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
247 {
248 	char strport[NI_MAXSERV];
249 	struct addrinfo hints, *res;
250 	int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
251 
252 	if (port <= 0)
253 		port = default_ssh_port();
254 
255 	snprintf(strport, sizeof strport, "%u", port);
256 	memset(&hints, 0, sizeof(hints));
257 	hints.ai_family = options.address_family == -1 ?
258 	    AF_UNSPEC : options.address_family;
259 	hints.ai_socktype = SOCK_STREAM;
260 	if (cname != NULL)
261 		hints.ai_flags = AI_CANONNAME;
262 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
263 		if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
264 			loglevel = SYSLOG_LEVEL_ERROR;
265 		do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
266 		    __progname, name, ssh_gai_strerror(gaierr));
267 		return NULL;
268 	}
269 	if (cname != NULL && res->ai_canonname != NULL) {
270 		if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
271 			error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
272 			    __func__, name,  res->ai_canonname, (u_long)clen);
273 			if (clen > 0)
274 				*cname = '\0';
275 		}
276 	}
277 	return res;
278 }
279 
280 /*
281  * Attempt to resolve a numeric host address / port to a single address.
282  * Returns a canonical address string.
283  * Returns NULL on failure.
284  * NB. this function must operate with a options having undefined members.
285  */
286 static struct addrinfo *
287 resolve_addr(const char *name, int port, char *caddr, size_t clen)
288 {
289 	char addr[NI_MAXHOST], strport[NI_MAXSERV];
290 	struct addrinfo hints, *res;
291 	int gaierr;
292 
293 	if (port <= 0)
294 		port = default_ssh_port();
295 	snprintf(strport, sizeof strport, "%u", port);
296 	memset(&hints, 0, sizeof(hints));
297 	hints.ai_family = options.address_family == -1 ?
298 	    AF_UNSPEC : options.address_family;
299 	hints.ai_socktype = SOCK_STREAM;
300 	hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
301 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
302 		debug2("%s: could not resolve name %.100s as address: %s",
303 		    __func__, name, ssh_gai_strerror(gaierr));
304 		return NULL;
305 	}
306 	if (res == NULL) {
307 		debug("%s: getaddrinfo %.100s returned no addresses",
308 		 __func__, name);
309 		return NULL;
310 	}
311 	if (res->ai_next != NULL) {
312 		debug("%s: getaddrinfo %.100s returned multiple addresses",
313 		    __func__, name);
314 		goto fail;
315 	}
316 	if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
317 	    addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
318 		debug("%s: Could not format address for name %.100s: %s",
319 		    __func__, name, ssh_gai_strerror(gaierr));
320 		goto fail;
321 	}
322 	if (strlcpy(caddr, addr, clen) >= clen) {
323 		error("%s: host \"%s\" addr \"%s\" too long (max %lu)",
324 		    __func__, name,  addr, (u_long)clen);
325 		if (clen > 0)
326 			*caddr = '\0';
327  fail:
328 		freeaddrinfo(res);
329 		return NULL;
330 	}
331 	return res;
332 }
333 
334 /*
335  * Check whether the cname is a permitted replacement for the hostname
336  * and perform the replacement if it is.
337  * NB. this function must operate with a options having undefined members.
338  */
339 static int
340 check_follow_cname(char **namep, const char *cname)
341 {
342 	int i;
343 	struct allowed_cname *rule;
344 
345 	if (*cname == '\0' || options.num_permitted_cnames == 0 ||
346 	    strcmp(*namep, cname) == 0)
347 		return 0;
348 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
349 		return 0;
350 	/*
351 	 * Don't attempt to canonicalize names that will be interpreted by
352 	 * a proxy unless the user specifically requests so.
353 	 */
354 	if (!option_clear_or_none(options.proxy_command) &&
355 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
356 		return 0;
357 	debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
358 	for (i = 0; i < options.num_permitted_cnames; i++) {
359 		rule = options.permitted_cnames + i;
360 		if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
361 		    match_pattern_list(cname, rule->target_list, 1) != 1)
362 			continue;
363 		verbose("Canonicalized DNS aliased hostname "
364 		    "\"%s\" => \"%s\"", *namep, cname);
365 		free(*namep);
366 		*namep = xstrdup(cname);
367 		return 1;
368 	}
369 	return 0;
370 }
371 
372 /*
373  * Attempt to resolve the supplied hostname after applying the user's
374  * canonicalization rules. Returns the address list for the host or NULL
375  * if no name was found after canonicalization.
376  * NB. this function must operate with a options having undefined members.
377  */
378 static struct addrinfo *
379 resolve_canonicalize(char **hostp, int port)
380 {
381 	int i, ndots;
382 	char *cp, *fullhost, newname[NI_MAXHOST];
383 	struct addrinfo *addrs;
384 
385 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
386 		return NULL;
387 
388 	/*
389 	 * Don't attempt to canonicalize names that will be interpreted by
390 	 * a proxy unless the user specifically requests so.
391 	 */
392 	if (!option_clear_or_none(options.proxy_command) &&
393 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
394 		return NULL;
395 
396 	/* Try numeric hostnames first */
397 	if ((addrs = resolve_addr(*hostp, port,
398 	    newname, sizeof(newname))) != NULL) {
399 		debug2("%s: hostname %.100s is address", __func__, *hostp);
400 		if (strcasecmp(*hostp, newname) != 0) {
401 			debug2("%s: canonicalised address \"%s\" => \"%s\"",
402 			    __func__, *hostp, newname);
403 			free(*hostp);
404 			*hostp = xstrdup(newname);
405 		}
406 		return addrs;
407 	}
408 
409 	/* Don't apply canonicalization to sufficiently-qualified hostnames */
410 	ndots = 0;
411 	for (cp = *hostp; *cp != '\0'; cp++) {
412 		if (*cp == '.')
413 			ndots++;
414 	}
415 	if (ndots > options.canonicalize_max_dots) {
416 		debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
417 		    __func__, *hostp, options.canonicalize_max_dots);
418 		return NULL;
419 	}
420 	/* Attempt each supplied suffix */
421 	for (i = 0; i < options.num_canonical_domains; i++) {
422 		*newname = '\0';
423 		xasprintf(&fullhost, "%s.%s.", *hostp,
424 		    options.canonical_domains[i]);
425 		debug3("%s: attempting \"%s\" => \"%s\"", __func__,
426 		    *hostp, fullhost);
427 		if ((addrs = resolve_host(fullhost, port, 0,
428 		    newname, sizeof(newname))) == NULL) {
429 			free(fullhost);
430 			continue;
431 		}
432 		/* Remove trailing '.' */
433 		fullhost[strlen(fullhost) - 1] = '\0';
434 		/* Follow CNAME if requested */
435 		if (!check_follow_cname(&fullhost, newname)) {
436 			debug("Canonicalized hostname \"%s\" => \"%s\"",
437 			    *hostp, fullhost);
438 		}
439 		free(*hostp);
440 		*hostp = fullhost;
441 		return addrs;
442 	}
443 	if (!options.canonicalize_fallback_local)
444 		fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
445 	debug2("%s: host %s not found in any suffix", __func__, *hostp);
446 	return NULL;
447 }
448 
449 /*
450  * Read per-user configuration file.  Ignore the system wide config
451  * file if the user specifies a config file on the command line.
452  */
453 static void
454 process_config_files(const char *host_arg, struct passwd *pw, int post_canon)
455 {
456 	char buf[PATH_MAX];
457 	int r;
458 
459 	if (config != NULL) {
460 		if (strcasecmp(config, "none") != 0 &&
461 		    !read_config_file(config, pw, host, host_arg, &options,
462 		    SSHCONF_USERCONF | (post_canon ? SSHCONF_POSTCANON : 0)))
463 			fatal("Can't open user config file %.100s: "
464 			    "%.100s", config, strerror(errno));
465 	} else {
466 		r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
467 		    _PATH_SSH_USER_CONFFILE);
468 		if (r > 0 && (size_t)r < sizeof(buf))
469 			(void)read_config_file(buf, pw, host, host_arg,
470 			    &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
471 			    (post_canon ? SSHCONF_POSTCANON : 0));
472 
473 		/* Read systemwide configuration file after user config. */
474 		(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
475 		    host, host_arg, &options,
476 		    post_canon ? SSHCONF_POSTCANON : 0);
477 	}
478 }
479 
480 /* Rewrite the port number in an addrinfo list of addresses */
481 static void
482 set_addrinfo_port(struct addrinfo *addrs, int port)
483 {
484 	struct addrinfo *addr;
485 
486 	for (addr = addrs; addr != NULL; addr = addr->ai_next) {
487 		switch (addr->ai_family) {
488 		case AF_INET:
489 			((struct sockaddr_in *)addr->ai_addr)->
490 			    sin_port = htons(port);
491 			break;
492 		case AF_INET6:
493 			((struct sockaddr_in6 *)addr->ai_addr)->
494 			    sin6_port = htons(port);
495 			break;
496 		}
497 	}
498 }
499 
500 /*
501  * Main program for the ssh client.
502  */
503 int
504 main(int ac, char **av)
505 {
506 	int i, r, opt, exit_status, use_syslog, config_test = 0;
507 	char *p, *cp, *line, *argv0, buf[PATH_MAX], *host_arg, *logfile;
508 	char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
509 	char cname[NI_MAXHOST];
510 	struct stat st;
511 	struct passwd *pw;
512 	int timeout_ms;
513 	extern int optind, optreset;
514 	extern char *optarg;
515 	struct Forward fwd;
516 	struct addrinfo *addrs = NULL;
517 	struct ssh_digest_ctx *md;
518 	u_char conn_hash[SSH_DIGEST_MAX_LENGTH];
519 	char *conn_hash_hex;
520 
521 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
522 	sanitise_stdfd();
523 
524 	__progname = ssh_get_progname(av[0]);
525 
526 #ifndef HAVE_SETPROCTITLE
527 	/* Prepare for later setproctitle emulation */
528 	/* Save argv so it isn't clobbered by setproctitle() emulation */
529 	saved_av = xcalloc(ac + 1, sizeof(*saved_av));
530 	for (i = 0; i < ac; i++)
531 		saved_av[i] = xstrdup(av[i]);
532 	saved_av[i] = NULL;
533 	compat_init_setproctitle(ac, av);
534 	av = saved_av;
535 #endif
536 
537 	/*
538 	 * Discard other fds that are hanging around. These can cause problem
539 	 * with backgrounded ssh processes started by ControlPersist.
540 	 */
541 	closefrom(STDERR_FILENO + 1);
542 
543 	/*
544 	 * Save the original real uid.  It will be needed later (uid-swapping
545 	 * may clobber the real uid).
546 	 */
547 	original_real_uid = getuid();
548 	original_effective_uid = geteuid();
549 
550 	/*
551 	 * Use uid-swapping to give up root privileges for the duration of
552 	 * option processing.  We will re-instantiate the rights when we are
553 	 * ready to create the privileged port, and will permanently drop
554 	 * them when the port has been created (actually, when the connection
555 	 * has been made, as we may need to create the port several times).
556 	 */
557 	PRIV_END;
558 
559 #ifdef HAVE_SETRLIMIT
560 	/* If we are installed setuid root be careful to not drop core. */
561 	if (original_real_uid != original_effective_uid) {
562 		struct rlimit rlim;
563 		rlim.rlim_cur = rlim.rlim_max = 0;
564 		if (setrlimit(RLIMIT_CORE, &rlim) < 0)
565 			fatal("setrlimit failed: %.100s", strerror(errno));
566 	}
567 #endif
568 	/* Get user data. */
569 	pw = getpwuid(original_real_uid);
570 	if (!pw) {
571 		logit("No user exists for uid %lu", (u_long)original_real_uid);
572 		exit(255);
573 	}
574 	/* Take a copy of the returned structure. */
575 	pw = pwcopy(pw);
576 
577 	/*
578 	 * Set our umask to something reasonable, as some files are created
579 	 * with the default umask.  This will make them world-readable but
580 	 * writable only by the owner, which is ok for all files for which we
581 	 * don't set the modes explicitly.
582 	 */
583 	umask(022);
584 
585 	/*
586 	 * Initialize option structure to indicate that no values have been
587 	 * set.
588 	 */
589 	initialize_options(&options);
590 
591 	/* Parse command-line arguments. */
592 	host = NULL;
593 	use_syslog = 0;
594 	logfile = NULL;
595 	argv0 = av[0];
596 
597  again:
598 	while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
599 	    "ACD:E:F:GI:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
600 		switch (opt) {
601 		case '1':
602 			options.protocol = SSH_PROTO_1;
603 			break;
604 		case '2':
605 			options.protocol = SSH_PROTO_2;
606 			break;
607 		case '4':
608 			options.address_family = AF_INET;
609 			break;
610 		case '6':
611 			options.address_family = AF_INET6;
612 			break;
613 		case 'n':
614 			stdin_null_flag = 1;
615 			break;
616 		case 'f':
617 			fork_after_authentication_flag = 1;
618 			stdin_null_flag = 1;
619 			break;
620 		case 'x':
621 			options.forward_x11 = 0;
622 			break;
623 		case 'X':
624 			options.forward_x11 = 1;
625 			break;
626 		case 'y':
627 			use_syslog = 1;
628 			break;
629 		case 'E':
630 			logfile = xstrdup(optarg);
631 			break;
632 		case 'G':
633 			config_test = 1;
634 			break;
635 		case 'Y':
636 			options.forward_x11 = 1;
637 			options.forward_x11_trusted = 1;
638 			break;
639 		case 'g':
640 			options.fwd_opts.gateway_ports = 1;
641 			break;
642 		case 'O':
643 			if (stdio_forward_host != NULL)
644 				fatal("Cannot specify multiplexing "
645 				    "command with -W");
646 			else if (muxclient_command != 0)
647 				fatal("Multiplexing command already specified");
648 			if (strcmp(optarg, "check") == 0)
649 				muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
650 			else if (strcmp(optarg, "forward") == 0)
651 				muxclient_command = SSHMUX_COMMAND_FORWARD;
652 			else if (strcmp(optarg, "exit") == 0)
653 				muxclient_command = SSHMUX_COMMAND_TERMINATE;
654 			else if (strcmp(optarg, "stop") == 0)
655 				muxclient_command = SSHMUX_COMMAND_STOP;
656 			else if (strcmp(optarg, "cancel") == 0)
657 				muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
658 			else
659 				fatal("Invalid multiplex command.");
660 			break;
661 		case 'P':	/* deprecated */
662 			options.use_privileged_port = 0;
663 			break;
664 		case 'Q':
665 			cp = NULL;
666 			if (strcmp(optarg, "cipher") == 0)
667 				cp = cipher_alg_list('\n', 0);
668 			else if (strcmp(optarg, "cipher-auth") == 0)
669 				cp = cipher_alg_list('\n', 1);
670 			else if (strcmp(optarg, "mac") == 0)
671 				cp = mac_alg_list('\n');
672 			else if (strcmp(optarg, "kex") == 0)
673 				cp = kex_alg_list('\n');
674 			else if (strcmp(optarg, "key") == 0)
675 				cp = key_alg_list(0, 0);
676 			else if (strcmp(optarg, "key-cert") == 0)
677 				cp = key_alg_list(1, 0);
678 			else if (strcmp(optarg, "key-plain") == 0)
679 				cp = key_alg_list(0, 1);
680 			else if (strcmp(optarg, "protocol-version") == 0) {
681 #ifdef WITH_SSH1
682 				cp = xstrdup("1\n2");
683 #else
684 				cp = xstrdup("2");
685 #endif
686 			}
687 			if (cp == NULL)
688 				fatal("Unsupported query \"%s\"", optarg);
689 			printf("%s\n", cp);
690 			free(cp);
691 			exit(0);
692 			break;
693 		case 'a':
694 			options.forward_agent = 0;
695 			break;
696 		case 'A':
697 			options.forward_agent = 1;
698 			break;
699 		case 'k':
700 			options.gss_deleg_creds = 0;
701 			break;
702 		case 'K':
703 			options.gss_authentication = 1;
704 			options.gss_deleg_creds = 1;
705 			break;
706 		case 'i':
707 			if (stat(optarg, &st) < 0) {
708 				fprintf(stderr, "Warning: Identity file %s "
709 				    "not accessible: %s.\n", optarg,
710 				    strerror(errno));
711 				break;
712 			}
713 			add_identity_file(&options, NULL, optarg, 1);
714 			break;
715 		case 'I':
716 #ifdef ENABLE_PKCS11
717 			options.pkcs11_provider = xstrdup(optarg);
718 #else
719 			fprintf(stderr, "no support for PKCS#11.\n");
720 #endif
721 			break;
722 		case 't':
723 			if (options.request_tty == REQUEST_TTY_YES)
724 				options.request_tty = REQUEST_TTY_FORCE;
725 			else
726 				options.request_tty = REQUEST_TTY_YES;
727 			break;
728 		case 'v':
729 			if (debug_flag == 0) {
730 				debug_flag = 1;
731 				options.log_level = SYSLOG_LEVEL_DEBUG1;
732 			} else {
733 				if (options.log_level < SYSLOG_LEVEL_DEBUG3)
734 					options.log_level++;
735 			}
736 			break;
737 		case 'V':
738 			if (options.version_addendum &&
739 			    *options.version_addendum != '\0')
740 				fprintf(stderr, "%s %s, %s\n", SSH_RELEASE,
741 				    options.version_addendum,
742 				    OPENSSL_VERSION);
743 			else
744 				fprintf(stderr, "%s, %s\n", SSH_RELEASE,
745 				    OPENSSL_VERSION);
746 			if (opt == 'V')
747 				exit(0);
748 			break;
749 		case 'w':
750 			if (options.tun_open == -1)
751 				options.tun_open = SSH_TUNMODE_DEFAULT;
752 			options.tun_local = a2tun(optarg, &options.tun_remote);
753 			if (options.tun_local == SSH_TUNID_ERR) {
754 				fprintf(stderr,
755 				    "Bad tun device '%s'\n", optarg);
756 				exit(255);
757 			}
758 			break;
759 		case 'W':
760 			if (stdio_forward_host != NULL)
761 				fatal("stdio forward already specified");
762 			if (muxclient_command != 0)
763 				fatal("Cannot specify stdio forward with -O");
764 			if (parse_forward(&fwd, optarg, 1, 0)) {
765 				stdio_forward_host = fwd.listen_host;
766 				stdio_forward_port = fwd.listen_port;
767 				free(fwd.connect_host);
768 			} else {
769 				fprintf(stderr,
770 				    "Bad stdio forwarding specification '%s'\n",
771 				    optarg);
772 				exit(255);
773 			}
774 			options.request_tty = REQUEST_TTY_NO;
775 			no_shell_flag = 1;
776 			options.clear_forwardings = 1;
777 			options.exit_on_forward_failure = 1;
778 			break;
779 		case 'q':
780 			options.log_level = SYSLOG_LEVEL_QUIET;
781 			break;
782 		case 'e':
783 			if (optarg[0] == '^' && optarg[2] == 0 &&
784 			    (u_char) optarg[1] >= 64 &&
785 			    (u_char) optarg[1] < 128)
786 				options.escape_char = (u_char) optarg[1] & 31;
787 			else if (strlen(optarg) == 1)
788 				options.escape_char = (u_char) optarg[0];
789 			else if (strcmp(optarg, "none") == 0)
790 				options.escape_char = SSH_ESCAPECHAR_NONE;
791 			else {
792 				fprintf(stderr, "Bad escape character '%s'.\n",
793 				    optarg);
794 				exit(255);
795 			}
796 			break;
797 		case 'c':
798 			if (ciphers_valid(optarg)) {
799 				/* SSH2 only */
800 				options.ciphers = xstrdup(optarg);
801 				options.cipher = SSH_CIPHER_INVALID;
802 			} else {
803 				/* SSH1 only */
804 				options.cipher = cipher_number(optarg);
805 				if (options.cipher == -1) {
806 					fprintf(stderr,
807 					    "Unknown cipher type '%s'\n",
808 					    optarg);
809 					exit(255);
810 				}
811 				if (options.cipher == SSH_CIPHER_3DES)
812 					options.ciphers = "3des-cbc";
813 				else if (options.cipher == SSH_CIPHER_BLOWFISH)
814 					options.ciphers = "blowfish-cbc";
815 				else
816 					options.ciphers = (char *)-1;
817 			}
818 			break;
819 		case 'm':
820 			if (mac_valid(optarg))
821 				options.macs = xstrdup(optarg);
822 			else {
823 				fprintf(stderr, "Unknown mac type '%s'\n",
824 				    optarg);
825 				exit(255);
826 			}
827 			break;
828 		case 'M':
829 			if (options.control_master == SSHCTL_MASTER_YES)
830 				options.control_master = SSHCTL_MASTER_ASK;
831 			else
832 				options.control_master = SSHCTL_MASTER_YES;
833 			break;
834 		case 'p':
835 			options.port = a2port(optarg);
836 			if (options.port <= 0) {
837 				fprintf(stderr, "Bad port '%s'\n", optarg);
838 				exit(255);
839 			}
840 			break;
841 		case 'l':
842 			options.user = optarg;
843 			break;
844 
845 		case 'L':
846 			if (parse_forward(&fwd, optarg, 0, 0))
847 				add_local_forward(&options, &fwd);
848 			else {
849 				fprintf(stderr,
850 				    "Bad local forwarding specification '%s'\n",
851 				    optarg);
852 				exit(255);
853 			}
854 			break;
855 
856 		case 'R':
857 			if (parse_forward(&fwd, optarg, 0, 1)) {
858 				add_remote_forward(&options, &fwd);
859 			} else {
860 				fprintf(stderr,
861 				    "Bad remote forwarding specification "
862 				    "'%s'\n", optarg);
863 				exit(255);
864 			}
865 			break;
866 
867 		case 'D':
868 			if (parse_forward(&fwd, optarg, 1, 0)) {
869 				add_local_forward(&options, &fwd);
870 			} else {
871 				fprintf(stderr,
872 				    "Bad dynamic forwarding specification "
873 				    "'%s'\n", optarg);
874 				exit(255);
875 			}
876 			break;
877 
878 		case 'C':
879 			options.compression = 1;
880 			break;
881 		case 'N':
882 			no_shell_flag = 1;
883 			options.request_tty = REQUEST_TTY_NO;
884 			break;
885 		case 'T':
886 			options.request_tty = REQUEST_TTY_NO;
887 			break;
888 		case 'o':
889 			line = xstrdup(optarg);
890 			if (process_config_line(&options, pw,
891 			    host ? host : "", host ? host : "", line,
892 			    "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
893 				exit(255);
894 			free(line);
895 			break;
896 		case 's':
897 			subsystem_flag = 1;
898 			break;
899 		case 'S':
900 			if (options.control_path != NULL)
901 				free(options.control_path);
902 			options.control_path = xstrdup(optarg);
903 			break;
904 		case 'b':
905 			options.bind_address = optarg;
906 			break;
907 		case 'F':
908 			config = optarg;
909 			break;
910 		default:
911 			usage();
912 		}
913 	}
914 
915 	ac -= optind;
916 	av += optind;
917 
918 	if (ac > 0 && !host) {
919 		if (strrchr(*av, '@')) {
920 			p = xstrdup(*av);
921 			cp = strrchr(p, '@');
922 			if (cp == NULL || cp == p)
923 				usage();
924 			options.user = p;
925 			*cp = '\0';
926 			host = xstrdup(++cp);
927 		} else
928 			host = xstrdup(*av);
929 		if (ac > 1) {
930 			optind = optreset = 1;
931 			goto again;
932 		}
933 		ac--, av++;
934 	}
935 
936 	/* Check that we got a host name. */
937 	if (!host)
938 		usage();
939 
940 	host_arg = xstrdup(host);
941 
942 #ifdef WITH_OPENSSL
943 	OpenSSL_add_all_algorithms();
944 	ERR_load_crypto_strings();
945 #endif
946 
947 	/* Initialize the command to execute on remote host. */
948 	buffer_init(&command);
949 
950 	/*
951 	 * Save the command to execute on the remote host in a buffer. There
952 	 * is no limit on the length of the command, except by the maximum
953 	 * packet size.  Also sets the tty flag if there is no command.
954 	 */
955 	if (!ac) {
956 		/* No command specified - execute shell on a tty. */
957 		if (subsystem_flag) {
958 			fprintf(stderr,
959 			    "You must specify a subsystem to invoke.\n");
960 			usage();
961 		}
962 	} else {
963 		/* A command has been specified.  Store it into the buffer. */
964 		for (i = 0; i < ac; i++) {
965 			if (i)
966 				buffer_append(&command, " ", 1);
967 			buffer_append(&command, av[i], strlen(av[i]));
968 		}
969 	}
970 
971 	/* Cannot fork to background if no command. */
972 	if (fork_after_authentication_flag && buffer_len(&command) == 0 &&
973 	    !no_shell_flag)
974 		fatal("Cannot fork into background without a command "
975 		    "to execute.");
976 
977 	/*
978 	 * Initialize "log" output.  Since we are the client all output
979 	 * goes to stderr unless otherwise specified by -y or -E.
980 	 */
981 	if (use_syslog && logfile != NULL)
982 		fatal("Can't specify both -y and -E");
983 	if (logfile != NULL) {
984 		log_redirect_stderr_to(logfile);
985 		free(logfile);
986 	}
987 	log_init(argv0,
988 	    options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
989 	    SYSLOG_FACILITY_USER, !use_syslog);
990 
991 	if (debug_flag)
992 		logit("%s, %s", SSH_RELEASE, OPENSSL_VERSION);
993 
994 	/* Parse the configuration files */
995 	process_config_files(host_arg, pw, 0);
996 
997 	/* Hostname canonicalisation needs a few options filled. */
998 	fill_default_options_for_canonicalization(&options);
999 
1000 	/* If the user has replaced the hostname then take it into use now */
1001 	if (options.hostname != NULL) {
1002 		/* NB. Please keep in sync with readconf.c:match_cfg_line() */
1003 		cp = percent_expand(options.hostname,
1004 		    "h", host, (char *)NULL);
1005 		free(host);
1006 		host = cp;
1007 		free(options.hostname);
1008 		options.hostname = xstrdup(host);
1009 	}
1010 
1011 	/* If canonicalization requested then try to apply it */
1012 	lowercase(host);
1013 	if (options.canonicalize_hostname != SSH_CANONICALISE_NO)
1014 		addrs = resolve_canonicalize(&host, options.port);
1015 
1016 	/*
1017 	 * If CanonicalizePermittedCNAMEs have been specified but
1018 	 * other canonicalization did not happen (by not being requested
1019 	 * or by failing with fallback) then the hostname may still be changed
1020 	 * as a result of CNAME following.
1021 	 *
1022 	 * Try to resolve the bare hostname name using the system resolver's
1023 	 * usual search rules and then apply the CNAME follow rules.
1024 	 *
1025 	 * Skip the lookup if a ProxyCommand is being used unless the user
1026 	 * has specifically requested canonicalisation for this case via
1027 	 * CanonicalizeHostname=always
1028 	 */
1029 	if (addrs == NULL && options.num_permitted_cnames != 0 &&
1030 	    (option_clear_or_none(options.proxy_command) ||
1031             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1032 		if ((addrs = resolve_host(host, options.port,
1033 		    option_clear_or_none(options.proxy_command),
1034 		    cname, sizeof(cname))) == NULL) {
1035 			/* Don't fatal proxied host names not in the DNS */
1036 			if (option_clear_or_none(options.proxy_command))
1037 				cleanup_exit(255); /* logged in resolve_host */
1038 		} else
1039 			check_follow_cname(&host, cname);
1040 	}
1041 
1042 	/*
1043 	 * If canonicalisation is enabled then re-parse the configuration
1044 	 * files as new stanzas may match.
1045 	 */
1046 	if (options.canonicalize_hostname != 0) {
1047 		debug("Re-reading configuration after hostname "
1048 		    "canonicalisation");
1049 		free(options.hostname);
1050 		options.hostname = xstrdup(host);
1051 		process_config_files(host_arg, pw, 1);
1052 		/*
1053 		 * Address resolution happens early with canonicalisation
1054 		 * enabled and the port number may have changed since, so
1055 		 * reset it in address list
1056 		 */
1057 		if (addrs != NULL && options.port > 0)
1058 			set_addrinfo_port(addrs, options.port);
1059 	}
1060 
1061 	/* Fill configuration defaults. */
1062 	fill_default_options(&options);
1063 
1064 	if (options.port == 0)
1065 		options.port = default_ssh_port();
1066 	channel_set_af(options.address_family);
1067 
1068 	/* Tidy and check options */
1069 	if (options.host_key_alias != NULL)
1070 		lowercase(options.host_key_alias);
1071 	if (options.proxy_command != NULL &&
1072 	    strcmp(options.proxy_command, "-") == 0 &&
1073 	    options.proxy_use_fdpass)
1074 		fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1075 	if (options.control_persist &&
1076 	    options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1077 		debug("UpdateHostKeys=ask is incompatible with ControlPersist; "
1078 		    "disabling");
1079 		options.update_hostkeys = 0;
1080 	}
1081 #ifndef HAVE_CYGWIN
1082 	if (original_effective_uid != 0)
1083 		options.use_privileged_port = 0;
1084 #endif
1085 
1086 	/* reinit */
1087 	log_init(argv0, options.log_level, SYSLOG_FACILITY_USER, !use_syslog);
1088 
1089 	if (options.request_tty == REQUEST_TTY_YES ||
1090 	    options.request_tty == REQUEST_TTY_FORCE)
1091 		tty_flag = 1;
1092 
1093 	/* Allocate a tty by default if no command specified. */
1094 	if (buffer_len(&command) == 0)
1095 		tty_flag = options.request_tty != REQUEST_TTY_NO;
1096 
1097 	/* Force no tty */
1098 	if (options.request_tty == REQUEST_TTY_NO || muxclient_command != 0)
1099 		tty_flag = 0;
1100 	/* Do not allocate a tty if stdin is not a tty. */
1101 	if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
1102 	    options.request_tty != REQUEST_TTY_FORCE) {
1103 		if (tty_flag)
1104 			logit("Pseudo-terminal will not be allocated because "
1105 			    "stdin is not a terminal.");
1106 		tty_flag = 0;
1107 	}
1108 
1109 	seed_rng();
1110 
1111 	if (options.user == NULL)
1112 		options.user = xstrdup(pw->pw_name);
1113 
1114 	if (gethostname(thishost, sizeof(thishost)) == -1)
1115 		fatal("gethostname: %s", strerror(errno));
1116 	strlcpy(shorthost, thishost, sizeof(shorthost));
1117 	shorthost[strcspn(thishost, ".")] = '\0';
1118 	snprintf(portstr, sizeof(portstr), "%d", options.port);
1119 
1120 	/* Find canonic host name. */
1121 	if (strchr(host, '.') == 0) {
1122 		struct addrinfo hints;
1123 		struct addrinfo *ai = NULL;
1124 		int errgai;
1125 		memset(&hints, 0, sizeof(hints));
1126 		hints.ai_family = options.address_family;
1127 		hints.ai_flags = AI_CANONNAME;
1128 		hints.ai_socktype = SOCK_STREAM;
1129 		errgai = getaddrinfo(host, NULL, &hints, &ai);
1130 		if (errgai == 0) {
1131 			if (ai->ai_canonname != NULL)
1132 				host = xstrdup(ai->ai_canonname);
1133 			freeaddrinfo(ai);
1134 		}
1135 	}
1136 
1137 	if ((md = ssh_digest_start(SSH_DIGEST_SHA1)) == NULL ||
1138 	    ssh_digest_update(md, thishost, strlen(thishost)) < 0 ||
1139 	    ssh_digest_update(md, host, strlen(host)) < 0 ||
1140 	    ssh_digest_update(md, portstr, strlen(portstr)) < 0 ||
1141 	    ssh_digest_update(md, options.user, strlen(options.user)) < 0 ||
1142 	    ssh_digest_final(md, conn_hash, sizeof(conn_hash)) < 0)
1143 		fatal("%s: mux digest failed", __func__);
1144 	ssh_digest_free(md);
1145 	conn_hash_hex = tohex(conn_hash, ssh_digest_bytes(SSH_DIGEST_SHA1));
1146 
1147 	if (options.local_command != NULL) {
1148 		debug3("expanding LocalCommand: %s", options.local_command);
1149 		cp = options.local_command;
1150 		options.local_command = percent_expand(cp,
1151 		    "C", conn_hash_hex,
1152 		    "L", shorthost,
1153 		    "d", pw->pw_dir,
1154 		    "h", host,
1155 		    "l", thishost,
1156 		    "n", host_arg,
1157 		    "p", portstr,
1158 		    "r", options.user,
1159 		    "u", pw->pw_name,
1160 		    (char *)NULL);
1161 		debug3("expanded LocalCommand: %s", options.local_command);
1162 		free(cp);
1163 	}
1164 
1165 	if (options.control_path != NULL) {
1166 		cp = tilde_expand_filename(options.control_path,
1167 		    original_real_uid);
1168 		free(options.control_path);
1169 		options.control_path = percent_expand(cp,
1170 		    "C", conn_hash_hex,
1171 		    "L", shorthost,
1172 		    "h", host,
1173 		    "l", thishost,
1174 		    "n", host_arg,
1175 		    "p", portstr,
1176 		    "r", options.user,
1177 		    "u", pw->pw_name,
1178 		    (char *)NULL);
1179 		free(cp);
1180 	}
1181 	free(conn_hash_hex);
1182 
1183 	if (config_test) {
1184 		dump_client_config(&options, host);
1185 		exit(0);
1186 	}
1187 
1188 	if (muxclient_command != 0 && options.control_path == NULL)
1189 		fatal("No ControlPath specified for \"-O\" command");
1190 	if (options.control_path != NULL)
1191 		muxclient(options.control_path);
1192 
1193 	/*
1194 	 * If hostname canonicalisation was not enabled, then we may not
1195 	 * have yet resolved the hostname. Do so now.
1196 	 */
1197 	if (addrs == NULL && options.proxy_command == NULL) {
1198 		if ((addrs = resolve_host(host, options.port, 1,
1199 		    cname, sizeof(cname))) == NULL)
1200 			cleanup_exit(255); /* resolve_host logs the error */
1201 	}
1202 
1203 	timeout_ms = options.connection_timeout * 1000;
1204 
1205 	/* Open a connection to the remote host. */
1206 	if (ssh_connect(host, addrs, &hostaddr, options.port,
1207 	    options.address_family, options.connection_attempts,
1208 	    &timeout_ms, options.tcp_keep_alive,
1209 	    options.use_privileged_port) != 0)
1210  		exit(255);
1211 
1212 	if (addrs != NULL)
1213 		freeaddrinfo(addrs);
1214 
1215 	packet_set_timeout(options.server_alive_interval,
1216 	    options.server_alive_count_max);
1217 
1218 	if (timeout_ms > 0)
1219 		debug3("timeout: %d ms remain after connect", timeout_ms);
1220 
1221 	/*
1222 	 * If we successfully made the connection, load the host private key
1223 	 * in case we will need it later for combined rsa-rhosts
1224 	 * authentication. This must be done before releasing extra
1225 	 * privileges, because the file is only readable by root.
1226 	 * If we cannot access the private keys, load the public keys
1227 	 * instead and try to execute the ssh-keysign helper instead.
1228 	 */
1229 	sensitive_data.nkeys = 0;
1230 	sensitive_data.keys = NULL;
1231 	sensitive_data.external_keysign = 0;
1232 	if (options.rhosts_rsa_authentication ||
1233 	    options.hostbased_authentication) {
1234 		sensitive_data.nkeys = 9;
1235 		sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1236 		    sizeof(Key));
1237 		for (i = 0; i < sensitive_data.nkeys; i++)
1238 			sensitive_data.keys[i] = NULL;
1239 
1240 		PRIV_START;
1241 		sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
1242 		    _PATH_HOST_KEY_FILE, "", NULL, NULL);
1243 #ifdef OPENSSL_HAS_ECC
1244 		sensitive_data.keys[1] = key_load_private_cert(KEY_ECDSA,
1245 		    _PATH_HOST_ECDSA_KEY_FILE, "", NULL);
1246 #endif
1247 		sensitive_data.keys[2] = key_load_private_cert(KEY_ED25519,
1248 		    _PATH_HOST_ED25519_KEY_FILE, "", NULL);
1249 		sensitive_data.keys[3] = key_load_private_cert(KEY_RSA,
1250 		    _PATH_HOST_RSA_KEY_FILE, "", NULL);
1251 		sensitive_data.keys[4] = key_load_private_cert(KEY_DSA,
1252 		    _PATH_HOST_DSA_KEY_FILE, "", NULL);
1253 #ifdef OPENSSL_HAS_ECC
1254 		sensitive_data.keys[5] = key_load_private_type(KEY_ECDSA,
1255 		    _PATH_HOST_ECDSA_KEY_FILE, "", NULL, NULL);
1256 #endif
1257 		sensitive_data.keys[6] = key_load_private_type(KEY_ED25519,
1258 		    _PATH_HOST_ED25519_KEY_FILE, "", NULL, NULL);
1259 		sensitive_data.keys[7] = key_load_private_type(KEY_RSA,
1260 		    _PATH_HOST_RSA_KEY_FILE, "", NULL, NULL);
1261 		sensitive_data.keys[8] = key_load_private_type(KEY_DSA,
1262 		    _PATH_HOST_DSA_KEY_FILE, "", NULL, NULL);
1263 		PRIV_END;
1264 
1265 		if (options.hostbased_authentication == 1 &&
1266 		    sensitive_data.keys[0] == NULL &&
1267 		    sensitive_data.keys[5] == NULL &&
1268 		    sensitive_data.keys[6] == NULL &&
1269 		    sensitive_data.keys[7] == NULL &&
1270 		    sensitive_data.keys[8] == NULL) {
1271 #ifdef OPENSSL_HAS_ECC
1272 			sensitive_data.keys[1] = key_load_cert(
1273 			    _PATH_HOST_ECDSA_KEY_FILE);
1274 #endif
1275 			sensitive_data.keys[2] = key_load_cert(
1276 			    _PATH_HOST_ED25519_KEY_FILE);
1277 			sensitive_data.keys[3] = key_load_cert(
1278 			    _PATH_HOST_RSA_KEY_FILE);
1279 			sensitive_data.keys[4] = key_load_cert(
1280 			    _PATH_HOST_DSA_KEY_FILE);
1281 #ifdef OPENSSL_HAS_ECC
1282 			sensitive_data.keys[5] = key_load_public(
1283 			    _PATH_HOST_ECDSA_KEY_FILE, NULL);
1284 #endif
1285 			sensitive_data.keys[6] = key_load_public(
1286 			    _PATH_HOST_ED25519_KEY_FILE, NULL);
1287 			sensitive_data.keys[7] = key_load_public(
1288 			    _PATH_HOST_RSA_KEY_FILE, NULL);
1289 			sensitive_data.keys[8] = key_load_public(
1290 			    _PATH_HOST_DSA_KEY_FILE, NULL);
1291 			sensitive_data.external_keysign = 1;
1292 		}
1293 	}
1294 	/*
1295 	 * Get rid of any extra privileges that we may have.  We will no
1296 	 * longer need them.  Also, extra privileges could make it very hard
1297 	 * to read identity files and other non-world-readable files from the
1298 	 * user's home directory if it happens to be on a NFS volume where
1299 	 * root is mapped to nobody.
1300 	 */
1301 	if (original_effective_uid == 0) {
1302 		PRIV_START;
1303 		permanently_set_uid(pw);
1304 	}
1305 
1306 	/*
1307 	 * Now that we are back to our own permissions, create ~/.ssh
1308 	 * directory if it doesn't already exist.
1309 	 */
1310 	if (config == NULL) {
1311 		r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1312 		    strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1313 		if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0) {
1314 #ifdef WITH_SELINUX
1315 			ssh_selinux_setfscreatecon(buf);
1316 #endif
1317 			if (mkdir(buf, 0700) < 0)
1318 				error("Could not create directory '%.200s'.",
1319 				    buf);
1320 #ifdef WITH_SELINUX
1321 			ssh_selinux_setfscreatecon(NULL);
1322 #endif
1323 		}
1324 	}
1325 	/* load options.identity_files */
1326 	load_public_identity_files();
1327 
1328 	/* Expand ~ in known host file names. */
1329 	tilde_expand_paths(options.system_hostfiles,
1330 	    options.num_system_hostfiles);
1331 	tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1332 
1333 	signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1334 	signal(SIGCHLD, main_sigchld_handler);
1335 
1336 	/* Log into the remote system.  Never returns if the login fails. */
1337 	ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1338 	    options.port, pw, timeout_ms);
1339 
1340 	if (packet_connection_is_on_socket()) {
1341 		verbose("Authenticated to %s ([%s]:%d).", host,
1342 		    get_remote_ipaddr(), get_remote_port());
1343 	} else {
1344 		verbose("Authenticated to %s (via proxy).", host);
1345 	}
1346 
1347 	/* We no longer need the private host keys.  Clear them now. */
1348 	if (sensitive_data.nkeys != 0) {
1349 		for (i = 0; i < sensitive_data.nkeys; i++) {
1350 			if (sensitive_data.keys[i] != NULL) {
1351 				/* Destroys contents safely */
1352 				debug3("clear hostkey %d", i);
1353 				key_free(sensitive_data.keys[i]);
1354 				sensitive_data.keys[i] = NULL;
1355 			}
1356 		}
1357 		free(sensitive_data.keys);
1358 	}
1359 	for (i = 0; i < options.num_identity_files; i++) {
1360 		free(options.identity_files[i]);
1361 		options.identity_files[i] = NULL;
1362 		if (options.identity_keys[i]) {
1363 			key_free(options.identity_keys[i]);
1364 			options.identity_keys[i] = NULL;
1365 		}
1366 	}
1367 
1368 	exit_status = compat20 ? ssh_session2() : ssh_session();
1369 	packet_close();
1370 
1371 	if (options.control_path != NULL && muxserver_sock != -1)
1372 		unlink(options.control_path);
1373 
1374 	/* Kill ProxyCommand if it is running. */
1375 	ssh_kill_proxy_command();
1376 
1377 	return exit_status;
1378 }
1379 
1380 static void
1381 control_persist_detach(void)
1382 {
1383 	pid_t pid;
1384 	int devnull;
1385 
1386 	debug("%s: backgrounding master process", __func__);
1387 
1388  	/*
1389  	 * master (current process) into the background, and make the
1390  	 * foreground process a client of the backgrounded master.
1391  	 */
1392 	switch ((pid = fork())) {
1393 	case -1:
1394 		fatal("%s: fork: %s", __func__, strerror(errno));
1395 	case 0:
1396 		/* Child: master process continues mainloop */
1397  		break;
1398  	default:
1399 		/* Parent: set up mux slave to connect to backgrounded master */
1400 		debug2("%s: background process is %ld", __func__, (long)pid);
1401 		stdin_null_flag = ostdin_null_flag;
1402 		options.request_tty = orequest_tty;
1403 		tty_flag = otty_flag;
1404  		close(muxserver_sock);
1405  		muxserver_sock = -1;
1406 		options.control_master = SSHCTL_MASTER_NO;
1407  		muxclient(options.control_path);
1408 		/* muxclient() doesn't return on success. */
1409  		fatal("Failed to connect to new control master");
1410  	}
1411 	if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1412 		error("%s: open(\"/dev/null\"): %s", __func__,
1413 		    strerror(errno));
1414 	} else {
1415 		if (dup2(devnull, STDIN_FILENO) == -1 ||
1416 		    dup2(devnull, STDOUT_FILENO) == -1)
1417 			error("%s: dup2: %s", __func__, strerror(errno));
1418 		if (devnull > STDERR_FILENO)
1419 			close(devnull);
1420 	}
1421 	daemon(1, 1);
1422 	setproctitle("%s [mux]", options.control_path);
1423 }
1424 
1425 /* Do fork() after authentication. Used by "ssh -f" */
1426 static void
1427 fork_postauth(void)
1428 {
1429 	if (need_controlpersist_detach)
1430 		control_persist_detach();
1431 	debug("forking to background");
1432 	fork_after_authentication_flag = 0;
1433 	if (daemon(1, 1) < 0)
1434 		fatal("daemon() failed: %.200s", strerror(errno));
1435 }
1436 
1437 /* Callback for remote forward global requests */
1438 static void
1439 ssh_confirm_remote_forward(int type, u_int32_t seq, void *ctxt)
1440 {
1441 	struct Forward *rfwd = (struct Forward *)ctxt;
1442 
1443 	/* XXX verbose() on failure? */
1444 	debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1445 	    type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1446 	    rfwd->listen_path ? rfwd->listen_path :
1447 	    rfwd->listen_host ? rfwd->listen_host : "",
1448 	    (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1449 	    rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1450 	    rfwd->connect_host, rfwd->connect_port);
1451 	if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1452 		if (type == SSH2_MSG_REQUEST_SUCCESS) {
1453 			rfwd->allocated_port = packet_get_int();
1454 			logit("Allocated port %u for remote forward to %s:%d",
1455 			    rfwd->allocated_port,
1456 			    rfwd->connect_host, rfwd->connect_port);
1457 			channel_update_permitted_opens(rfwd->handle,
1458 			    rfwd->allocated_port);
1459 		} else {
1460 			channel_update_permitted_opens(rfwd->handle, -1);
1461 		}
1462 	}
1463 
1464 	if (type == SSH2_MSG_REQUEST_FAILURE) {
1465 		if (options.exit_on_forward_failure) {
1466 			if (rfwd->listen_path != NULL)
1467 				fatal("Error: remote port forwarding failed "
1468 				    "for listen path %s", rfwd->listen_path);
1469 			else
1470 				fatal("Error: remote port forwarding failed "
1471 				    "for listen port %d", rfwd->listen_port);
1472 		} else {
1473 			if (rfwd->listen_path != NULL)
1474 				logit("Warning: remote port forwarding failed "
1475 				    "for listen path %s", rfwd->listen_path);
1476 			else
1477 				logit("Warning: remote port forwarding failed "
1478 				    "for listen port %d", rfwd->listen_port);
1479 		}
1480 	}
1481 	if (++remote_forward_confirms_received == options.num_remote_forwards) {
1482 		debug("All remote forwarding requests processed");
1483 		if (fork_after_authentication_flag)
1484 			fork_postauth();
1485 	}
1486 }
1487 
1488 static void
1489 client_cleanup_stdio_fwd(int id, void *arg)
1490 {
1491 	debug("stdio forwarding: done");
1492 	cleanup_exit(0);
1493 }
1494 
1495 static void
1496 ssh_stdio_confirm(int id, int success, void *arg)
1497 {
1498 	if (!success)
1499 		fatal("stdio forwarding failed");
1500 }
1501 
1502 static void
1503 ssh_init_stdio_forwarding(void)
1504 {
1505 	Channel *c;
1506 	int in, out;
1507 
1508 	if (stdio_forward_host == NULL)
1509 		return;
1510 	if (!compat20)
1511 		fatal("stdio forwarding require Protocol 2");
1512 
1513 	debug3("%s: %s:%d", __func__, stdio_forward_host, stdio_forward_port);
1514 
1515 	if ((in = dup(STDIN_FILENO)) < 0 ||
1516 	    (out = dup(STDOUT_FILENO)) < 0)
1517 		fatal("channel_connect_stdio_fwd: dup() in/out failed");
1518 	if ((c = channel_connect_stdio_fwd(stdio_forward_host,
1519 	    stdio_forward_port, in, out)) == NULL)
1520 		fatal("%s: channel_connect_stdio_fwd failed", __func__);
1521 	channel_register_cleanup(c->self, client_cleanup_stdio_fwd, 0);
1522 	channel_register_open_confirm(c->self, ssh_stdio_confirm, NULL);
1523 }
1524 
1525 static void
1526 ssh_init_forwarding(void)
1527 {
1528 	int success = 0;
1529 	int i;
1530 
1531 	/* Initiate local TCP/IP port forwardings. */
1532 	for (i = 0; i < options.num_local_forwards; i++) {
1533 		debug("Local connections to %.200s:%d forwarded to remote "
1534 		    "address %.200s:%d",
1535 		    (options.local_forwards[i].listen_path != NULL) ?
1536 		    options.local_forwards[i].listen_path :
1537 		    (options.local_forwards[i].listen_host == NULL) ?
1538 		    (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1539 		    options.local_forwards[i].listen_host,
1540 		    options.local_forwards[i].listen_port,
1541 		    (options.local_forwards[i].connect_path != NULL) ?
1542 		    options.local_forwards[i].connect_path :
1543 		    options.local_forwards[i].connect_host,
1544 		    options.local_forwards[i].connect_port);
1545 		success += channel_setup_local_fwd_listener(
1546 		    &options.local_forwards[i], &options.fwd_opts);
1547 	}
1548 	if (i > 0 && success != i && options.exit_on_forward_failure)
1549 		fatal("Could not request local forwarding.");
1550 	if (i > 0 && success == 0)
1551 		error("Could not request local forwarding.");
1552 
1553 	/* Initiate remote TCP/IP port forwardings. */
1554 	for (i = 0; i < options.num_remote_forwards; i++) {
1555 		debug("Remote connections from %.200s:%d forwarded to "
1556 		    "local address %.200s:%d",
1557 		    (options.remote_forwards[i].listen_path != NULL) ?
1558 		    options.remote_forwards[i].listen_path :
1559 		    (options.remote_forwards[i].listen_host == NULL) ?
1560 		    "LOCALHOST" : options.remote_forwards[i].listen_host,
1561 		    options.remote_forwards[i].listen_port,
1562 		    (options.remote_forwards[i].connect_path != NULL) ?
1563 		    options.remote_forwards[i].connect_path :
1564 		    options.remote_forwards[i].connect_host,
1565 		    options.remote_forwards[i].connect_port);
1566 		options.remote_forwards[i].handle =
1567 		    channel_request_remote_forwarding(
1568 		    &options.remote_forwards[i]);
1569 		if (options.remote_forwards[i].handle < 0) {
1570 			if (options.exit_on_forward_failure)
1571 				fatal("Could not request remote forwarding.");
1572 			else
1573 				logit("Warning: Could not request remote "
1574 				    "forwarding.");
1575 		} else {
1576 			client_register_global_confirm(ssh_confirm_remote_forward,
1577 			    &options.remote_forwards[i]);
1578 		}
1579 	}
1580 
1581 	/* Initiate tunnel forwarding. */
1582 	if (options.tun_open != SSH_TUNMODE_NO) {
1583 		if (client_request_tun_fwd(options.tun_open,
1584 		    options.tun_local, options.tun_remote) == -1) {
1585 			if (options.exit_on_forward_failure)
1586 				fatal("Could not request tunnel forwarding.");
1587 			else
1588 				error("Could not request tunnel forwarding.");
1589 		}
1590 	}
1591 }
1592 
1593 static void
1594 check_agent_present(void)
1595 {
1596 	int r;
1597 
1598 	if (options.forward_agent) {
1599 		/* Clear agent forwarding if we don't have an agent. */
1600 		if ((r = ssh_get_authentication_socket(NULL)) != 0) {
1601 			options.forward_agent = 0;
1602 			if (r != SSH_ERR_AGENT_NOT_PRESENT)
1603 				debug("ssh_get_authentication_socket: %s",
1604 				    ssh_err(r));
1605 		}
1606 	}
1607 }
1608 
1609 static int
1610 ssh_session(void)
1611 {
1612 	int type;
1613 	int interactive = 0;
1614 	int have_tty = 0;
1615 	struct winsize ws;
1616 	char *cp;
1617 	const char *display;
1618 
1619 	/* Enable compression if requested. */
1620 	if (options.compression) {
1621 		debug("Requesting compression at level %d.",
1622 		    options.compression_level);
1623 
1624 		if (options.compression_level < 1 ||
1625 		    options.compression_level > 9)
1626 			fatal("Compression level must be from 1 (fast) to "
1627 			    "9 (slow, best).");
1628 
1629 		/* Send the request. */
1630 		packet_start(SSH_CMSG_REQUEST_COMPRESSION);
1631 		packet_put_int(options.compression_level);
1632 		packet_send();
1633 		packet_write_wait();
1634 		type = packet_read();
1635 		if (type == SSH_SMSG_SUCCESS)
1636 			packet_start_compression(options.compression_level);
1637 		else if (type == SSH_SMSG_FAILURE)
1638 			logit("Warning: Remote host refused compression.");
1639 		else
1640 			packet_disconnect("Protocol error waiting for "
1641 			    "compression response.");
1642 	}
1643 	/* Allocate a pseudo tty if appropriate. */
1644 	if (tty_flag) {
1645 		debug("Requesting pty.");
1646 
1647 		/* Start the packet. */
1648 		packet_start(SSH_CMSG_REQUEST_PTY);
1649 
1650 		/* Store TERM in the packet.  There is no limit on the
1651 		   length of the string. */
1652 		cp = getenv("TERM");
1653 		if (!cp)
1654 			cp = "";
1655 		packet_put_cstring(cp);
1656 
1657 		/* Store window size in the packet. */
1658 		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1659 			memset(&ws, 0, sizeof(ws));
1660 		packet_put_int((u_int)ws.ws_row);
1661 		packet_put_int((u_int)ws.ws_col);
1662 		packet_put_int((u_int)ws.ws_xpixel);
1663 		packet_put_int((u_int)ws.ws_ypixel);
1664 
1665 		/* Store tty modes in the packet. */
1666 		tty_make_modes(fileno(stdin), NULL);
1667 
1668 		/* Send the packet, and wait for it to leave. */
1669 		packet_send();
1670 		packet_write_wait();
1671 
1672 		/* Read response from the server. */
1673 		type = packet_read();
1674 		if (type == SSH_SMSG_SUCCESS) {
1675 			interactive = 1;
1676 			have_tty = 1;
1677 		} else if (type == SSH_SMSG_FAILURE)
1678 			logit("Warning: Remote host failed or refused to "
1679 			    "allocate a pseudo tty.");
1680 		else
1681 			packet_disconnect("Protocol error waiting for pty "
1682 			    "request response.");
1683 	}
1684 	/* Request X11 forwarding if enabled and DISPLAY is set. */
1685 	display = getenv("DISPLAY");
1686 	if (display == NULL && options.forward_x11)
1687 		debug("X11 forwarding requested but DISPLAY not set");
1688 	if (options.forward_x11 && display != NULL) {
1689 		char *proto, *data;
1690 		/* Get reasonable local authentication information. */
1691 		client_x11_get_proto(display, options.xauth_location,
1692 		    options.forward_x11_trusted,
1693 		    options.forward_x11_timeout,
1694 		    &proto, &data);
1695 		/* Request forwarding with authentication spoofing. */
1696 		debug("Requesting X11 forwarding with authentication "
1697 		    "spoofing.");
1698 		x11_request_forwarding_with_spoofing(0, display, proto,
1699 		    data, 0);
1700 		/* Read response from the server. */
1701 		type = packet_read();
1702 		if (type == SSH_SMSG_SUCCESS) {
1703 			interactive = 1;
1704 		} else if (type == SSH_SMSG_FAILURE) {
1705 			logit("Warning: Remote host denied X11 forwarding.");
1706 		} else {
1707 			packet_disconnect("Protocol error waiting for X11 "
1708 			    "forwarding");
1709 		}
1710 	}
1711 	/* Tell the packet module whether this is an interactive session. */
1712 	packet_set_interactive(interactive,
1713 	    options.ip_qos_interactive, options.ip_qos_bulk);
1714 
1715 	/* Request authentication agent forwarding if appropriate. */
1716 	check_agent_present();
1717 
1718 	if (options.forward_agent) {
1719 		debug("Requesting authentication agent forwarding.");
1720 		auth_request_forwarding();
1721 
1722 		/* Read response from the server. */
1723 		type = packet_read();
1724 		packet_check_eom();
1725 		if (type != SSH_SMSG_SUCCESS)
1726 			logit("Warning: Remote host denied authentication agent forwarding.");
1727 	}
1728 
1729 	/* Initiate port forwardings. */
1730 	ssh_init_stdio_forwarding();
1731 	ssh_init_forwarding();
1732 
1733 	/* Execute a local command */
1734 	if (options.local_command != NULL &&
1735 	    options.permit_local_command)
1736 		ssh_local_cmd(options.local_command);
1737 
1738 	/*
1739 	 * If requested and we are not interested in replies to remote
1740 	 * forwarding requests, then let ssh continue in the background.
1741 	 */
1742 	if (fork_after_authentication_flag) {
1743 		if (options.exit_on_forward_failure &&
1744 		    options.num_remote_forwards > 0) {
1745 			debug("deferring postauth fork until remote forward "
1746 			    "confirmation received");
1747 		} else
1748 			fork_postauth();
1749 	}
1750 
1751 	/*
1752 	 * If a command was specified on the command line, execute the
1753 	 * command now. Otherwise request the server to start a shell.
1754 	 */
1755 	if (buffer_len(&command) > 0) {
1756 		int len = buffer_len(&command);
1757 		if (len > 900)
1758 			len = 900;
1759 		debug("Sending command: %.*s", len,
1760 		    (u_char *)buffer_ptr(&command));
1761 		packet_start(SSH_CMSG_EXEC_CMD);
1762 		packet_put_string(buffer_ptr(&command), buffer_len(&command));
1763 		packet_send();
1764 		packet_write_wait();
1765 	} else {
1766 		debug("Requesting shell.");
1767 		packet_start(SSH_CMSG_EXEC_SHELL);
1768 		packet_send();
1769 		packet_write_wait();
1770 	}
1771 
1772 	/* Enter the interactive session. */
1773 	return client_loop(have_tty, tty_flag ?
1774 	    options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1775 }
1776 
1777 /* request pty/x11/agent/tcpfwd/shell for channel */
1778 static void
1779 ssh_session2_setup(int id, int success, void *arg)
1780 {
1781 	extern char **environ;
1782 	const char *display;
1783 	int interactive = tty_flag;
1784 
1785 	if (!success)
1786 		return; /* No need for error message, channels code sens one */
1787 
1788 	display = getenv("DISPLAY");
1789 	if (display == NULL && options.forward_x11)
1790 		debug("X11 forwarding requested but DISPLAY not set");
1791 	if (options.forward_x11 && display != NULL) {
1792 		char *proto, *data;
1793 		/* Get reasonable local authentication information. */
1794 		client_x11_get_proto(display, options.xauth_location,
1795 		    options.forward_x11_trusted,
1796 		    options.forward_x11_timeout, &proto, &data);
1797 		/* Request forwarding with authentication spoofing. */
1798 		debug("Requesting X11 forwarding with authentication "
1799 		    "spoofing.");
1800 		x11_request_forwarding_with_spoofing(id, display, proto,
1801 		    data, 1);
1802 		client_expect_confirm(id, "X11 forwarding", CONFIRM_WARN);
1803 		/* XXX exit_on_forward_failure */
1804 		interactive = 1;
1805 	}
1806 
1807 	check_agent_present();
1808 	if (options.forward_agent) {
1809 		debug("Requesting authentication agent forwarding.");
1810 		channel_request_start(id, "auth-agent-req@openssh.com", 0);
1811 		packet_send();
1812 	}
1813 
1814 	/* Tell the packet module whether this is an interactive session. */
1815 	packet_set_interactive(interactive,
1816 	    options.ip_qos_interactive, options.ip_qos_bulk);
1817 
1818 	client_session2_setup(id, tty_flag, subsystem_flag, getenv("TERM"),
1819 	    NULL, fileno(stdin), &command, environ);
1820 }
1821 
1822 /* open new channel for a session */
1823 static int
1824 ssh_session2_open(void)
1825 {
1826 	Channel *c;
1827 	int window, packetmax, in, out, err;
1828 
1829 	if (stdin_null_flag) {
1830 		in = open(_PATH_DEVNULL, O_RDONLY);
1831 	} else {
1832 		in = dup(STDIN_FILENO);
1833 	}
1834 	out = dup(STDOUT_FILENO);
1835 	err = dup(STDERR_FILENO);
1836 
1837 	if (in < 0 || out < 0 || err < 0)
1838 		fatal("dup() in/out/err failed");
1839 
1840 	/* enable nonblocking unless tty */
1841 	if (!isatty(in))
1842 		set_nonblock(in);
1843 	if (!isatty(out))
1844 		set_nonblock(out);
1845 	if (!isatty(err))
1846 		set_nonblock(err);
1847 
1848 	window = CHAN_SES_WINDOW_DEFAULT;
1849 	packetmax = CHAN_SES_PACKET_DEFAULT;
1850 	if (tty_flag) {
1851 		window >>= 1;
1852 		packetmax >>= 1;
1853 	}
1854 	c = channel_new(
1855 	    "session", SSH_CHANNEL_OPENING, in, out, err,
1856 	    window, packetmax, CHAN_EXTENDED_WRITE,
1857 	    "client-session", /*nonblock*/0);
1858 
1859 	debug3("ssh_session2_open: channel_new: %d", c->self);
1860 
1861 	channel_send_open(c->self);
1862 	if (!no_shell_flag)
1863 		channel_register_open_confirm(c->self,
1864 		    ssh_session2_setup, NULL);
1865 
1866 	return c->self;
1867 }
1868 
1869 static int
1870 ssh_session2(void)
1871 {
1872 	int id = -1;
1873 
1874 	/* XXX should be pre-session */
1875 	if (!options.control_persist)
1876 		ssh_init_stdio_forwarding();
1877 	ssh_init_forwarding();
1878 
1879 	/* Start listening for multiplex clients */
1880 	muxserver_listen();
1881 
1882  	/*
1883 	 * If we are in control persist mode and have a working mux listen
1884 	 * socket, then prepare to background ourselves and have a foreground
1885 	 * client attach as a control slave.
1886 	 * NB. we must save copies of the flags that we override for
1887 	 * the backgrounding, since we defer attachment of the slave until
1888 	 * after the connection is fully established (in particular,
1889 	 * async rfwd replies have been received for ExitOnForwardFailure).
1890 	 */
1891  	if (options.control_persist && muxserver_sock != -1) {
1892 		ostdin_null_flag = stdin_null_flag;
1893 		ono_shell_flag = no_shell_flag;
1894 		orequest_tty = options.request_tty;
1895 		otty_flag = tty_flag;
1896  		stdin_null_flag = 1;
1897  		no_shell_flag = 1;
1898  		tty_flag = 0;
1899 		if (!fork_after_authentication_flag)
1900 			need_controlpersist_detach = 1;
1901 		fork_after_authentication_flag = 1;
1902  	}
1903 	/*
1904 	 * ControlPersist mux listen socket setup failed, attempt the
1905 	 * stdio forward setup that we skipped earlier.
1906 	 */
1907 	if (options.control_persist && muxserver_sock == -1)
1908 		ssh_init_stdio_forwarding();
1909 
1910 	if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1911 		id = ssh_session2_open();
1912 	else {
1913 		packet_set_interactive(
1914 		    options.control_master == SSHCTL_MASTER_NO,
1915 		    options.ip_qos_interactive, options.ip_qos_bulk);
1916 	}
1917 
1918 	/* If we don't expect to open a new session, then disallow it */
1919 	if (options.control_master == SSHCTL_MASTER_NO &&
1920 	    (datafellows & SSH_NEW_OPENSSH)) {
1921 		debug("Requesting no-more-sessions@openssh.com");
1922 		packet_start(SSH2_MSG_GLOBAL_REQUEST);
1923 		packet_put_cstring("no-more-sessions@openssh.com");
1924 		packet_put_char(0);
1925 		packet_send();
1926 	}
1927 
1928 	/* Execute a local command */
1929 	if (options.local_command != NULL &&
1930 	    options.permit_local_command)
1931 		ssh_local_cmd(options.local_command);
1932 
1933 	/*
1934 	 * If requested and we are not interested in replies to remote
1935 	 * forwarding requests, then let ssh continue in the background.
1936 	 */
1937 	if (fork_after_authentication_flag) {
1938 		if (options.exit_on_forward_failure &&
1939 		    options.num_remote_forwards > 0) {
1940 			debug("deferring postauth fork until remote forward "
1941 			    "confirmation received");
1942 		} else
1943 			fork_postauth();
1944 	}
1945 
1946 	return client_loop(tty_flag, tty_flag ?
1947 	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
1948 }
1949 
1950 static void
1951 load_public_identity_files(void)
1952 {
1953 	char *filename, *cp, thishost[NI_MAXHOST];
1954 	char *pwdir = NULL, *pwname = NULL;
1955 	int i = 0;
1956 	Key *public;
1957 	struct passwd *pw;
1958 	u_int n_ids;
1959 	char *identity_files[SSH_MAX_IDENTITY_FILES];
1960 	Key *identity_keys[SSH_MAX_IDENTITY_FILES];
1961 #ifdef ENABLE_PKCS11
1962 	Key **keys;
1963 	int nkeys;
1964 #endif /* PKCS11 */
1965 
1966 	n_ids = 0;
1967 	memset(identity_files, 0, sizeof(identity_files));
1968 	memset(identity_keys, 0, sizeof(identity_keys));
1969 
1970 #ifdef ENABLE_PKCS11
1971 	if (options.pkcs11_provider != NULL &&
1972 	    options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1973 	    (pkcs11_init(!options.batch_mode) == 0) &&
1974 	    (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1975 	    &keys)) > 0) {
1976 		for (i = 0; i < nkeys; i++) {
1977 			if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1978 				key_free(keys[i]);
1979 				continue;
1980 			}
1981 			identity_keys[n_ids] = keys[i];
1982 			identity_files[n_ids] =
1983 			    xstrdup(options.pkcs11_provider); /* XXX */
1984 			n_ids++;
1985 		}
1986 		free(keys);
1987 	}
1988 #endif /* ENABLE_PKCS11 */
1989 	if ((pw = getpwuid(original_real_uid)) == NULL)
1990 		fatal("load_public_identity_files: getpwuid failed");
1991 	pwname = xstrdup(pw->pw_name);
1992 	pwdir = xstrdup(pw->pw_dir);
1993 	if (gethostname(thishost, sizeof(thishost)) == -1)
1994 		fatal("load_public_identity_files: gethostname: %s",
1995 		    strerror(errno));
1996 	for (i = 0; i < options.num_identity_files; i++) {
1997 		if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1998 		    strcasecmp(options.identity_files[i], "none") == 0) {
1999 			free(options.identity_files[i]);
2000 			continue;
2001 		}
2002 		cp = tilde_expand_filename(options.identity_files[i],
2003 		    original_real_uid);
2004 		filename = percent_expand(cp, "d", pwdir,
2005 		    "u", pwname, "l", thishost, "h", host,
2006 		    "r", options.user, (char *)NULL);
2007 		free(cp);
2008 		public = key_load_public(filename, NULL);
2009 		debug("identity file %s type %d", filename,
2010 		    public ? public->type : -1);
2011 		free(options.identity_files[i]);
2012 		identity_files[n_ids] = filename;
2013 		identity_keys[n_ids] = public;
2014 
2015 		if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2016 			continue;
2017 
2018 		/* Try to add the certificate variant too */
2019 		xasprintf(&cp, "%s-cert", filename);
2020 		public = key_load_public(cp, NULL);
2021 		debug("identity file %s type %d", cp,
2022 		    public ? public->type : -1);
2023 		if (public == NULL) {
2024 			free(cp);
2025 			continue;
2026 		}
2027 		if (!key_is_cert(public)) {
2028 			debug("%s: key %s type %s is not a certificate",
2029 			    __func__, cp, key_type(public));
2030 			key_free(public);
2031 			free(cp);
2032 			continue;
2033 		}
2034 		identity_keys[n_ids] = public;
2035 		/* point to the original path, most likely the private key */
2036 		identity_files[n_ids] = xstrdup(filename);
2037 		n_ids++;
2038 	}
2039 	options.num_identity_files = n_ids;
2040 	memcpy(options.identity_files, identity_files, sizeof(identity_files));
2041 	memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2042 
2043 	explicit_bzero(pwname, strlen(pwname));
2044 	free(pwname);
2045 	explicit_bzero(pwdir, strlen(pwdir));
2046 	free(pwdir);
2047 }
2048 
2049 static void
2050 main_sigchld_handler(int sig)
2051 {
2052 	int save_errno = errno;
2053 	pid_t pid;
2054 	int status;
2055 
2056 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2057 	    (pid < 0 && errno == EINTR))
2058 		;
2059 
2060 	signal(sig, main_sigchld_handler);
2061 	errno = save_errno;
2062 }
2063