xref: /openbsd-src/usr.bin/ssh/ssh.c (revision d1df930ffab53da22f3324c32bed7ac5709915e6)
1 /* $OpenBSD: ssh.c,v 1.494 2018/10/03 06:38:35 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  * Ssh client program.  This program can be used to log into a remote machine.
7  * The software supports strong authentication, encryption, and forwarding
8  * of X11, TCP/IP, and authentication connections.
9  *
10  * As far as I am concerned, the code I have written for this software
11  * can be used freely for any purpose.  Any derived versions of this
12  * software must be clearly marked as such, and if the derived work is
13  * incompatible with the protocol description in the RFC file, it must be
14  * called by a name other than "ssh" or "Secure Shell".
15  *
16  * Copyright (c) 1999 Niels Provos.  All rights reserved.
17  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
18  *
19  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
20  * in Canada (German citizen).
21  *
22  * Redistribution and use in source and binary forms, with or without
23  * modification, are permitted provided that the following conditions
24  * are met:
25  * 1. Redistributions of source code must retain the above copyright
26  *    notice, this list of conditions and the following disclaimer.
27  * 2. Redistributions in binary form must reproduce the above copyright
28  *    notice, this list of conditions and the following disclaimer in the
29  *    documentation and/or other materials provided with the distribution.
30  *
31  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
32  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
34  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
35  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
37  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
38  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
39  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
40  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41  */
42 
43 #include <sys/types.h>
44 #include <sys/ioctl.h>
45 #include <sys/queue.h>
46 #include <sys/resource.h>
47 #include <sys/socket.h>
48 #include <sys/stat.h>
49 #include <sys/time.h>
50 #include <sys/wait.h>
51 
52 #include <ctype.h>
53 #include <errno.h>
54 #include <fcntl.h>
55 #include <netdb.h>
56 #include <paths.h>
57 #include <pwd.h>
58 #include <signal.h>
59 #include <stddef.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
64 #include <limits.h>
65 #include <locale.h>
66 
67 #ifdef WITH_OPENSSL
68 #include <openssl/evp.h>
69 #include <openssl/err.h>
70 #endif
71 
72 #include "xmalloc.h"
73 #include "ssh.h"
74 #include "ssh2.h"
75 #include "canohost.h"
76 #include "compat.h"
77 #include "cipher.h"
78 #include "digest.h"
79 #include "packet.h"
80 #include "sshbuf.h"
81 #include "channels.h"
82 #include "sshkey.h"
83 #include "authfd.h"
84 #include "authfile.h"
85 #include "pathnames.h"
86 #include "dispatch.h"
87 #include "clientloop.h"
88 #include "log.h"
89 #include "misc.h"
90 #include "readconf.h"
91 #include "sshconnect.h"
92 #include "kex.h"
93 #include "mac.h"
94 #include "sshpty.h"
95 #include "match.h"
96 #include "msg.h"
97 #include "version.h"
98 #include "ssherr.h"
99 #include "myproposal.h"
100 
101 #ifdef ENABLE_PKCS11
102 #include "ssh-pkcs11.h"
103 #endif
104 
105 extern char *__progname;
106 
107 /* Flag indicating whether debug mode is on.  May be set on the command line. */
108 int debug_flag = 0;
109 
110 /* Flag indicating whether a tty should be requested */
111 int tty_flag = 0;
112 
113 /* don't exec a shell */
114 int no_shell_flag = 0;
115 
116 /*
117  * Flag indicating that nothing should be read from stdin.  This can be set
118  * on the command line.
119  */
120 int stdin_null_flag = 0;
121 
122 /*
123  * Flag indicating that the current process should be backgrounded and
124  * a new slave launched in the foreground for ControlPersist.
125  */
126 int need_controlpersist_detach = 0;
127 
128 /* Copies of flags for ControlPersist foreground slave */
129 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
130 
131 /*
132  * Flag indicating that ssh should fork after authentication.  This is useful
133  * so that the passphrase can be entered manually, and then ssh goes to the
134  * background.
135  */
136 int fork_after_authentication_flag = 0;
137 
138 /*
139  * General data structure for command line options and options configurable
140  * in configuration files.  See readconf.h.
141  */
142 Options options;
143 
144 /* optional user configfile */
145 char *config = NULL;
146 
147 /*
148  * Name of the host we are connecting to.  This is the name given on the
149  * command line, or the HostName specified for the user-supplied name in a
150  * configuration file.
151  */
152 char *host;
153 
154 /* Various strings used to to percent_expand() arguments */
155 static char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
156 static char uidstr[32], *host_arg, *conn_hash_hex;
157 
158 /* socket address the host resolves to */
159 struct sockaddr_storage hostaddr;
160 
161 /* Private host keys. */
162 Sensitive sensitive_data;
163 
164 /* command to be executed */
165 struct sshbuf *command;
166 
167 /* Should we execute a command or invoke a subsystem? */
168 int subsystem_flag = 0;
169 
170 /* # of replies received for global requests */
171 static int remote_forward_confirms_received = 0;
172 
173 /* mux.c */
174 extern int muxserver_sock;
175 extern u_int muxclient_command;
176 
177 /* Prints a help message to the user.  This function never returns. */
178 
179 static void
180 usage(void)
181 {
182 	fprintf(stderr,
183 "usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
184 "           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
185 "           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
186 "           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
187 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
188 "           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
189 "           [-w local_tun[:remote_tun]] destination [command]\n"
190 	);
191 	exit(255);
192 }
193 
194 static int ssh_session2(struct ssh *, struct passwd *);
195 static void load_public_identity_files(struct passwd *);
196 static void main_sigchld_handler(int);
197 
198 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
199 static void
200 tilde_expand_paths(char **paths, u_int num_paths)
201 {
202 	u_int i;
203 	char *cp;
204 
205 	for (i = 0; i < num_paths; i++) {
206 		cp = tilde_expand_filename(paths[i], getuid());
207 		free(paths[i]);
208 		paths[i] = cp;
209 	}
210 }
211 
212 /*
213  * Attempt to resolve a host name / port to a set of addresses and
214  * optionally return any CNAMEs encountered along the way.
215  * Returns NULL on failure.
216  * NB. this function must operate with a options having undefined members.
217  */
218 static struct addrinfo *
219 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
220 {
221 	char strport[NI_MAXSERV];
222 	struct addrinfo hints, *res;
223 	int gaierr, loglevel = SYSLOG_LEVEL_DEBUG1;
224 
225 	if (port <= 0)
226 		port = default_ssh_port();
227 
228 	snprintf(strport, sizeof strport, "%d", port);
229 	memset(&hints, 0, sizeof(hints));
230 	hints.ai_family = options.address_family == -1 ?
231 	    AF_UNSPEC : options.address_family;
232 	hints.ai_socktype = SOCK_STREAM;
233 	if (cname != NULL)
234 		hints.ai_flags = AI_CANONNAME;
235 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
236 		if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
237 			loglevel = SYSLOG_LEVEL_ERROR;
238 		do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
239 		    __progname, name, ssh_gai_strerror(gaierr));
240 		return NULL;
241 	}
242 	if (cname != NULL && res->ai_canonname != NULL) {
243 		if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
244 			error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
245 			    __func__, name,  res->ai_canonname, (u_long)clen);
246 			if (clen > 0)
247 				*cname = '\0';
248 		}
249 	}
250 	return res;
251 }
252 
253 /* Returns non-zero if name can only be an address and not a hostname */
254 static int
255 is_addr_fast(const char *name)
256 {
257 	return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
258 	    strspn(name, "0123456789.") == strlen(name));
259 }
260 
261 /* Returns non-zero if name represents a valid, single address */
262 static int
263 is_addr(const char *name)
264 {
265 	char strport[NI_MAXSERV];
266 	struct addrinfo hints, *res;
267 
268 	if (is_addr_fast(name))
269 		return 1;
270 
271 	snprintf(strport, sizeof strport, "%u", default_ssh_port());
272 	memset(&hints, 0, sizeof(hints));
273 	hints.ai_family = options.address_family == -1 ?
274 	    AF_UNSPEC : options.address_family;
275 	hints.ai_socktype = SOCK_STREAM;
276 	hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
277 	if (getaddrinfo(name, strport, &hints, &res) != 0)
278 		return 0;
279 	if (res == NULL || res->ai_next != NULL) {
280 		freeaddrinfo(res);
281 		return 0;
282 	}
283 	freeaddrinfo(res);
284 	return 1;
285 }
286 
287 /*
288  * Attempt to resolve a numeric host address / port to a single address.
289  * Returns a canonical address string.
290  * Returns NULL on failure.
291  * NB. this function must operate with a options having undefined members.
292  */
293 static struct addrinfo *
294 resolve_addr(const char *name, int port, char *caddr, size_t clen)
295 {
296 	char addr[NI_MAXHOST], strport[NI_MAXSERV];
297 	struct addrinfo hints, *res;
298 	int gaierr;
299 
300 	if (port <= 0)
301 		port = default_ssh_port();
302 	snprintf(strport, sizeof strport, "%u", port);
303 	memset(&hints, 0, sizeof(hints));
304 	hints.ai_family = options.address_family == -1 ?
305 	    AF_UNSPEC : options.address_family;
306 	hints.ai_socktype = SOCK_STREAM;
307 	hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
308 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
309 		debug2("%s: could not resolve name %.100s as address: %s",
310 		    __func__, name, ssh_gai_strerror(gaierr));
311 		return NULL;
312 	}
313 	if (res == NULL) {
314 		debug("%s: getaddrinfo %.100s returned no addresses",
315 		 __func__, name);
316 		return NULL;
317 	}
318 	if (res->ai_next != NULL) {
319 		debug("%s: getaddrinfo %.100s returned multiple addresses",
320 		    __func__, name);
321 		goto fail;
322 	}
323 	if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
324 	    addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
325 		debug("%s: Could not format address for name %.100s: %s",
326 		    __func__, name, ssh_gai_strerror(gaierr));
327 		goto fail;
328 	}
329 	if (strlcpy(caddr, addr, clen) >= clen) {
330 		error("%s: host \"%s\" addr \"%s\" too long (max %lu)",
331 		    __func__, name,  addr, (u_long)clen);
332 		if (clen > 0)
333 			*caddr = '\0';
334  fail:
335 		freeaddrinfo(res);
336 		return NULL;
337 	}
338 	return res;
339 }
340 
341 /*
342  * Check whether the cname is a permitted replacement for the hostname
343  * and perform the replacement if it is.
344  * NB. this function must operate with a options having undefined members.
345  */
346 static int
347 check_follow_cname(int direct, char **namep, const char *cname)
348 {
349 	int i;
350 	struct allowed_cname *rule;
351 
352 	if (*cname == '\0' || options.num_permitted_cnames == 0 ||
353 	    strcmp(*namep, cname) == 0)
354 		return 0;
355 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
356 		return 0;
357 	/*
358 	 * Don't attempt to canonicalize names that will be interpreted by
359 	 * a proxy or jump host unless the user specifically requests so.
360 	 */
361 	if (!direct &&
362 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
363 		return 0;
364 	debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
365 	for (i = 0; i < options.num_permitted_cnames; i++) {
366 		rule = options.permitted_cnames + i;
367 		if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
368 		    match_pattern_list(cname, rule->target_list, 1) != 1)
369 			continue;
370 		verbose("Canonicalized DNS aliased hostname "
371 		    "\"%s\" => \"%s\"", *namep, cname);
372 		free(*namep);
373 		*namep = xstrdup(cname);
374 		return 1;
375 	}
376 	return 0;
377 }
378 
379 /*
380  * Attempt to resolve the supplied hostname after applying the user's
381  * canonicalization rules. Returns the address list for the host or NULL
382  * if no name was found after canonicalization.
383  * NB. this function must operate with a options having undefined members.
384  */
385 static struct addrinfo *
386 resolve_canonicalize(char **hostp, int port)
387 {
388 	int i, direct, ndots;
389 	char *cp, *fullhost, newname[NI_MAXHOST];
390 	struct addrinfo *addrs;
391 
392 	/*
393 	 * Attempt to canonicalise addresses, regardless of
394 	 * whether hostname canonicalisation was requested
395 	 */
396 	if ((addrs = resolve_addr(*hostp, port,
397 	    newname, sizeof(newname))) != NULL) {
398 		debug2("%s: hostname %.100s is address", __func__, *hostp);
399 		if (strcasecmp(*hostp, newname) != 0) {
400 			debug2("%s: canonicalised address \"%s\" => \"%s\"",
401 			    __func__, *hostp, newname);
402 			free(*hostp);
403 			*hostp = xstrdup(newname);
404 		}
405 		return addrs;
406 	}
407 
408 	/*
409 	 * If this looks like an address but didn't parse as one, it might
410 	 * be an address with an invalid interface scope. Skip further
411 	 * attempts at canonicalisation.
412 	 */
413 	if (is_addr_fast(*hostp)) {
414 		debug("%s: hostname %.100s is an unrecognised address",
415 		    __func__, *hostp);
416 		return NULL;
417 	}
418 
419 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
420 		return NULL;
421 
422 	/*
423 	 * Don't attempt to canonicalize names that will be interpreted by
424 	 * a proxy unless the user specifically requests so.
425 	 */
426 	direct = option_clear_or_none(options.proxy_command) &&
427 	    options.jump_host == NULL;
428 	if (!direct &&
429 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
430 		return NULL;
431 
432 	/* If domain name is anchored, then resolve it now */
433 	if ((*hostp)[strlen(*hostp) - 1] == '.') {
434 		debug3("%s: name is fully qualified", __func__);
435 		fullhost = xstrdup(*hostp);
436 		if ((addrs = resolve_host(fullhost, port, 0,
437 		    newname, sizeof(newname))) != NULL)
438 			goto found;
439 		free(fullhost);
440 		goto notfound;
441 	}
442 
443 	/* Don't apply canonicalization to sufficiently-qualified hostnames */
444 	ndots = 0;
445 	for (cp = *hostp; *cp != '\0'; cp++) {
446 		if (*cp == '.')
447 			ndots++;
448 	}
449 	if (ndots > options.canonicalize_max_dots) {
450 		debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
451 		    __func__, *hostp, options.canonicalize_max_dots);
452 		return NULL;
453 	}
454 	/* Attempt each supplied suffix */
455 	for (i = 0; i < options.num_canonical_domains; i++) {
456 		*newname = '\0';
457 		xasprintf(&fullhost, "%s.%s.", *hostp,
458 		    options.canonical_domains[i]);
459 		debug3("%s: attempting \"%s\" => \"%s\"", __func__,
460 		    *hostp, fullhost);
461 		if ((addrs = resolve_host(fullhost, port, 0,
462 		    newname, sizeof(newname))) == NULL) {
463 			free(fullhost);
464 			continue;
465 		}
466  found:
467 		/* Remove trailing '.' */
468 		fullhost[strlen(fullhost) - 1] = '\0';
469 		/* Follow CNAME if requested */
470 		if (!check_follow_cname(direct, &fullhost, newname)) {
471 			debug("Canonicalized hostname \"%s\" => \"%s\"",
472 			    *hostp, fullhost);
473 		}
474 		free(*hostp);
475 		*hostp = fullhost;
476 		return addrs;
477 	}
478  notfound:
479 	if (!options.canonicalize_fallback_local)
480 		fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
481 	debug2("%s: host %s not found in any suffix", __func__, *hostp);
482 	return NULL;
483 }
484 
485 /*
486  * Check the result of hostkey loading, ignoring some errors and
487  * fatal()ing for others.
488  */
489 static void
490 check_load(int r, const char *path, const char *message)
491 {
492 	switch (r) {
493 	case 0:
494 		break;
495 	case SSH_ERR_INTERNAL_ERROR:
496 	case SSH_ERR_ALLOC_FAIL:
497 		fatal("load %s \"%s\": %s", message, path, ssh_err(r));
498 	case SSH_ERR_SYSTEM_ERROR:
499 		/* Ignore missing files */
500 		if (errno == ENOENT)
501 			break;
502 		/* FALLTHROUGH */
503 	default:
504 		error("load %s \"%s\": %s", message, path, ssh_err(r));
505 		break;
506 	}
507 }
508 
509 /*
510  * Read per-user configuration file.  Ignore the system wide config
511  * file if the user specifies a config file on the command line.
512  */
513 static void
514 process_config_files(const char *host_name, struct passwd *pw, int post_canon)
515 {
516 	char buf[PATH_MAX];
517 	int r;
518 
519 	if (config != NULL) {
520 		if (strcasecmp(config, "none") != 0 &&
521 		    !read_config_file(config, pw, host, host_name, &options,
522 		    SSHCONF_USERCONF | (post_canon ? SSHCONF_POSTCANON : 0)))
523 			fatal("Can't open user config file %.100s: "
524 			    "%.100s", config, strerror(errno));
525 	} else {
526 		r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
527 		    _PATH_SSH_USER_CONFFILE);
528 		if (r > 0 && (size_t)r < sizeof(buf))
529 			(void)read_config_file(buf, pw, host, host_name,
530 			    &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
531 			    (post_canon ? SSHCONF_POSTCANON : 0));
532 
533 		/* Read systemwide configuration file after user config. */
534 		(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
535 		    host, host_name, &options,
536 		    post_canon ? SSHCONF_POSTCANON : 0);
537 	}
538 }
539 
540 /* Rewrite the port number in an addrinfo list of addresses */
541 static void
542 set_addrinfo_port(struct addrinfo *addrs, int port)
543 {
544 	struct addrinfo *addr;
545 
546 	for (addr = addrs; addr != NULL; addr = addr->ai_next) {
547 		switch (addr->ai_family) {
548 		case AF_INET:
549 			((struct sockaddr_in *)addr->ai_addr)->
550 			    sin_port = htons(port);
551 			break;
552 		case AF_INET6:
553 			((struct sockaddr_in6 *)addr->ai_addr)->
554 			    sin6_port = htons(port);
555 			break;
556 		}
557 	}
558 }
559 
560 /*
561  * Main program for the ssh client.
562  */
563 int
564 main(int ac, char **av)
565 {
566 	struct ssh *ssh = NULL;
567 	int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
568 	int was_addr, config_test = 0, opt_terminated = 0;
569 	char *p, *cp, *line, *argv0, buf[PATH_MAX], *logfile;
570 	char cname[NI_MAXHOST];
571 	struct stat st;
572 	struct passwd *pw;
573 	extern int optind, optreset;
574 	extern char *optarg;
575 	struct Forward fwd;
576 	struct addrinfo *addrs = NULL;
577 	struct ssh_digest_ctx *md;
578 	u_char conn_hash[SSH_DIGEST_MAX_LENGTH];
579 
580 	ssh_malloc_init();	/* must be called before any mallocs */
581 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
582 	sanitise_stdfd();
583 
584 	/*
585 	 * Discard other fds that are hanging around. These can cause problem
586 	 * with backgrounded ssh processes started by ControlPersist.
587 	 */
588 	closefrom(STDERR_FILENO + 1);
589 
590 	if (getuid() != geteuid())
591 		fatal("ssh setuid not supported.");
592 	if (getgid() != getegid())
593 		fatal("ssh setgid not supported.");
594 
595 	/* Get user data. */
596 	pw = getpwuid(getuid());
597 	if (!pw) {
598 		logit("No user exists for uid %lu", (u_long)getuid());
599 		exit(255);
600 	}
601 	/* Take a copy of the returned structure. */
602 	pw = pwcopy(pw);
603 
604 	/*
605 	 * Set our umask to something reasonable, as some files are created
606 	 * with the default umask.  This will make them world-readable but
607 	 * writable only by the owner, which is ok for all files for which we
608 	 * don't set the modes explicitly.
609 	 */
610 	umask(022);
611 
612 	setlocale(LC_CTYPE, "");
613 
614 	/*
615 	 * Initialize option structure to indicate that no values have been
616 	 * set.
617 	 */
618 	initialize_options(&options);
619 
620 	/*
621 	 * Prepare main ssh transport/connection structures
622 	 */
623 	if ((ssh = ssh_alloc_session_state()) == NULL)
624 		fatal("Couldn't allocate session state");
625 	channel_init_channels(ssh);
626 	active_state = ssh; /* XXX legacy API compat */
627 
628 	/* Parse command-line arguments. */
629 	host = NULL;
630 	use_syslog = 0;
631 	logfile = NULL;
632 	argv0 = av[0];
633 
634  again:
635 	while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
636 	    "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
637 		switch (opt) {
638 		case '1':
639 			fatal("SSH protocol v.1 is no longer supported");
640 			break;
641 		case '2':
642 			/* Ignored */
643 			break;
644 		case '4':
645 			options.address_family = AF_INET;
646 			break;
647 		case '6':
648 			options.address_family = AF_INET6;
649 			break;
650 		case 'n':
651 			stdin_null_flag = 1;
652 			break;
653 		case 'f':
654 			fork_after_authentication_flag = 1;
655 			stdin_null_flag = 1;
656 			break;
657 		case 'x':
658 			options.forward_x11 = 0;
659 			break;
660 		case 'X':
661 			options.forward_x11 = 1;
662 			break;
663 		case 'y':
664 			use_syslog = 1;
665 			break;
666 		case 'E':
667 			logfile = optarg;
668 			break;
669 		case 'G':
670 			config_test = 1;
671 			break;
672 		case 'Y':
673 			options.forward_x11 = 1;
674 			options.forward_x11_trusted = 1;
675 			break;
676 		case 'g':
677 			options.fwd_opts.gateway_ports = 1;
678 			break;
679 		case 'O':
680 			if (options.stdio_forward_host != NULL)
681 				fatal("Cannot specify multiplexing "
682 				    "command with -W");
683 			else if (muxclient_command != 0)
684 				fatal("Multiplexing command already specified");
685 			if (strcmp(optarg, "check") == 0)
686 				muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
687 			else if (strcmp(optarg, "forward") == 0)
688 				muxclient_command = SSHMUX_COMMAND_FORWARD;
689 			else if (strcmp(optarg, "exit") == 0)
690 				muxclient_command = SSHMUX_COMMAND_TERMINATE;
691 			else if (strcmp(optarg, "stop") == 0)
692 				muxclient_command = SSHMUX_COMMAND_STOP;
693 			else if (strcmp(optarg, "cancel") == 0)
694 				muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
695 			else if (strcmp(optarg, "proxy") == 0)
696 				muxclient_command = SSHMUX_COMMAND_PROXY;
697 			else
698 				fatal("Invalid multiplex command.");
699 			break;
700 		case 'P':	/* deprecated */
701 			break;
702 		case 'Q':
703 			cp = NULL;
704 			if (strcmp(optarg, "cipher") == 0)
705 				cp = cipher_alg_list('\n', 0);
706 			else if (strcmp(optarg, "cipher-auth") == 0)
707 				cp = cipher_alg_list('\n', 1);
708 			else if (strcmp(optarg, "mac") == 0)
709 				cp = mac_alg_list('\n');
710 			else if (strcmp(optarg, "kex") == 0)
711 				cp = kex_alg_list('\n');
712 			else if (strcmp(optarg, "key") == 0)
713 				cp = sshkey_alg_list(0, 0, 0, '\n');
714 			else if (strcmp(optarg, "key-cert") == 0)
715 				cp = sshkey_alg_list(1, 0, 0, '\n');
716 			else if (strcmp(optarg, "key-plain") == 0)
717 				cp = sshkey_alg_list(0, 1, 0, '\n');
718 			else if (strcmp(optarg, "sig") == 0)
719 				cp = sshkey_alg_list(0, 1, 1, '\n');
720 			else if (strcmp(optarg, "protocol-version") == 0)
721 				cp = xstrdup("2");
722 			else if (strcmp(optarg, "help") == 0) {
723 				cp = xstrdup(
724 				    "cipher\ncipher-auth\nkex\nkey\n"
725 				    "key-cert\nkey-plain\nmac\n"
726 				    "protocol-version\nsig");
727 			}
728 			if (cp == NULL)
729 				fatal("Unsupported query \"%s\"", optarg);
730 			printf("%s\n", cp);
731 			free(cp);
732 			exit(0);
733 			break;
734 		case 'a':
735 			options.forward_agent = 0;
736 			break;
737 		case 'A':
738 			options.forward_agent = 1;
739 			break;
740 		case 'k':
741 			options.gss_deleg_creds = 0;
742 			break;
743 		case 'K':
744 			options.gss_authentication = 1;
745 			options.gss_deleg_creds = 1;
746 			break;
747 		case 'i':
748 			p = tilde_expand_filename(optarg, getuid());
749 			if (stat(p, &st) < 0)
750 				fprintf(stderr, "Warning: Identity file %s "
751 				    "not accessible: %s.\n", p,
752 				    strerror(errno));
753 			else
754 				add_identity_file(&options, NULL, p, 1);
755 			free(p);
756 			break;
757 		case 'I':
758 #ifdef ENABLE_PKCS11
759 			free(options.pkcs11_provider);
760 			options.pkcs11_provider = xstrdup(optarg);
761 #else
762 			fprintf(stderr, "no support for PKCS#11.\n");
763 #endif
764 			break;
765 		case 'J':
766 			if (options.jump_host != NULL)
767 				fatal("Only a single -J option permitted");
768 			if (options.proxy_command != NULL)
769 				fatal("Cannot specify -J with ProxyCommand");
770 			if (parse_jump(optarg, &options, 1) == -1)
771 				fatal("Invalid -J argument");
772 			options.proxy_command = xstrdup("none");
773 			break;
774 		case 't':
775 			if (options.request_tty == REQUEST_TTY_YES)
776 				options.request_tty = REQUEST_TTY_FORCE;
777 			else
778 				options.request_tty = REQUEST_TTY_YES;
779 			break;
780 		case 'v':
781 			if (debug_flag == 0) {
782 				debug_flag = 1;
783 				options.log_level = SYSLOG_LEVEL_DEBUG1;
784 			} else {
785 				if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
786 					debug_flag++;
787 					options.log_level++;
788 				}
789 			}
790 			break;
791 		case 'V':
792 			fprintf(stderr, "%s, %s\n",
793 			    SSH_VERSION,
794 #ifdef WITH_OPENSSL
795 			    SSLeay_version(SSLEAY_VERSION)
796 #else
797 			    "without OpenSSL"
798 #endif
799 			);
800 			if (opt == 'V')
801 				exit(0);
802 			break;
803 		case 'w':
804 			if (options.tun_open == -1)
805 				options.tun_open = SSH_TUNMODE_DEFAULT;
806 			options.tun_local = a2tun(optarg, &options.tun_remote);
807 			if (options.tun_local == SSH_TUNID_ERR) {
808 				fprintf(stderr,
809 				    "Bad tun device '%s'\n", optarg);
810 				exit(255);
811 			}
812 			break;
813 		case 'W':
814 			if (options.stdio_forward_host != NULL)
815 				fatal("stdio forward already specified");
816 			if (muxclient_command != 0)
817 				fatal("Cannot specify stdio forward with -O");
818 			if (parse_forward(&fwd, optarg, 1, 0)) {
819 				options.stdio_forward_host = fwd.listen_host;
820 				options.stdio_forward_port = fwd.listen_port;
821 				free(fwd.connect_host);
822 			} else {
823 				fprintf(stderr,
824 				    "Bad stdio forwarding specification '%s'\n",
825 				    optarg);
826 				exit(255);
827 			}
828 			options.request_tty = REQUEST_TTY_NO;
829 			no_shell_flag = 1;
830 			break;
831 		case 'q':
832 			options.log_level = SYSLOG_LEVEL_QUIET;
833 			break;
834 		case 'e':
835 			if (optarg[0] == '^' && optarg[2] == 0 &&
836 			    (u_char) optarg[1] >= 64 &&
837 			    (u_char) optarg[1] < 128)
838 				options.escape_char = (u_char) optarg[1] & 31;
839 			else if (strlen(optarg) == 1)
840 				options.escape_char = (u_char) optarg[0];
841 			else if (strcmp(optarg, "none") == 0)
842 				options.escape_char = SSH_ESCAPECHAR_NONE;
843 			else {
844 				fprintf(stderr, "Bad escape character '%s'.\n",
845 				    optarg);
846 				exit(255);
847 			}
848 			break;
849 		case 'c':
850 			if (!ciphers_valid(*optarg == '+' ?
851 			    optarg + 1 : optarg)) {
852 				fprintf(stderr, "Unknown cipher type '%s'\n",
853 				    optarg);
854 				exit(255);
855 			}
856 			free(options.ciphers);
857 			options.ciphers = xstrdup(optarg);
858 			break;
859 		case 'm':
860 			if (mac_valid(optarg)) {
861 				free(options.macs);
862 				options.macs = xstrdup(optarg);
863 			} else {
864 				fprintf(stderr, "Unknown mac type '%s'\n",
865 				    optarg);
866 				exit(255);
867 			}
868 			break;
869 		case 'M':
870 			if (options.control_master == SSHCTL_MASTER_YES)
871 				options.control_master = SSHCTL_MASTER_ASK;
872 			else
873 				options.control_master = SSHCTL_MASTER_YES;
874 			break;
875 		case 'p':
876 			if (options.port == -1) {
877 				options.port = a2port(optarg);
878 				if (options.port <= 0) {
879 					fprintf(stderr, "Bad port '%s'\n",
880 					    optarg);
881 					exit(255);
882 				}
883 			}
884 			break;
885 		case 'l':
886 			if (options.user == NULL)
887 				options.user = optarg;
888 			break;
889 
890 		case 'L':
891 			if (parse_forward(&fwd, optarg, 0, 0))
892 				add_local_forward(&options, &fwd);
893 			else {
894 				fprintf(stderr,
895 				    "Bad local forwarding specification '%s'\n",
896 				    optarg);
897 				exit(255);
898 			}
899 			break;
900 
901 		case 'R':
902 			if (parse_forward(&fwd, optarg, 0, 1) ||
903 			    parse_forward(&fwd, optarg, 1, 1)) {
904 				add_remote_forward(&options, &fwd);
905 			} else {
906 				fprintf(stderr,
907 				    "Bad remote forwarding specification "
908 				    "'%s'\n", optarg);
909 				exit(255);
910 			}
911 			break;
912 
913 		case 'D':
914 			if (parse_forward(&fwd, optarg, 1, 0)) {
915 				add_local_forward(&options, &fwd);
916 			} else {
917 				fprintf(stderr,
918 				    "Bad dynamic forwarding specification "
919 				    "'%s'\n", optarg);
920 				exit(255);
921 			}
922 			break;
923 
924 		case 'C':
925 			options.compression = 1;
926 			break;
927 		case 'N':
928 			no_shell_flag = 1;
929 			options.request_tty = REQUEST_TTY_NO;
930 			break;
931 		case 'T':
932 			options.request_tty = REQUEST_TTY_NO;
933 			break;
934 		case 'o':
935 			line = xstrdup(optarg);
936 			if (process_config_line(&options, pw,
937 			    host ? host : "", host ? host : "", line,
938 			    "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
939 				exit(255);
940 			free(line);
941 			break;
942 		case 's':
943 			subsystem_flag = 1;
944 			break;
945 		case 'S':
946 			free(options.control_path);
947 			options.control_path = xstrdup(optarg);
948 			break;
949 		case 'b':
950 			options.bind_address = optarg;
951 			break;
952 		case 'B':
953 			options.bind_interface = optarg;
954 			break;
955 		case 'F':
956 			config = optarg;
957 			break;
958 		default:
959 			usage();
960 		}
961 	}
962 
963 	if (optind > 1 && strcmp(av[optind - 1], "--") == 0)
964 		opt_terminated = 1;
965 
966 	ac -= optind;
967 	av += optind;
968 
969 	if (ac > 0 && !host) {
970 		int tport;
971 		char *tuser;
972 		switch (parse_ssh_uri(*av, &tuser, &host, &tport)) {
973 		case -1:
974 			usage();
975 			break;
976 		case 0:
977 			if (options.user == NULL) {
978 				options.user = tuser;
979 				tuser = NULL;
980 			}
981 			free(tuser);
982 			if (options.port == -1 && tport != -1)
983 				options.port = tport;
984 			break;
985 		default:
986 			p = xstrdup(*av);
987 			cp = strrchr(p, '@');
988 			if (cp != NULL) {
989 				if (cp == p)
990 					usage();
991 				if (options.user == NULL) {
992 					options.user = p;
993 					p = NULL;
994 				}
995 				*cp++ = '\0';
996 				host = xstrdup(cp);
997 				free(p);
998 			} else
999 				host = p;
1000 			break;
1001 		}
1002 		if (ac > 1 && !opt_terminated) {
1003 			optind = optreset = 1;
1004 			goto again;
1005 		}
1006 		ac--, av++;
1007 	}
1008 
1009 	/* Check that we got a host name. */
1010 	if (!host)
1011 		usage();
1012 
1013 	host_arg = xstrdup(host);
1014 
1015 #ifdef WITH_OPENSSL
1016 	OpenSSL_add_all_algorithms();
1017 	ERR_load_crypto_strings();
1018 #endif
1019 
1020 	/* Initialize the command to execute on remote host. */
1021 	if ((command = sshbuf_new()) == NULL)
1022 		fatal("sshbuf_new failed");
1023 
1024 	/*
1025 	 * Save the command to execute on the remote host in a buffer. There
1026 	 * is no limit on the length of the command, except by the maximum
1027 	 * packet size.  Also sets the tty flag if there is no command.
1028 	 */
1029 	if (!ac) {
1030 		/* No command specified - execute shell on a tty. */
1031 		if (subsystem_flag) {
1032 			fprintf(stderr,
1033 			    "You must specify a subsystem to invoke.\n");
1034 			usage();
1035 		}
1036 	} else {
1037 		/* A command has been specified.  Store it into the buffer. */
1038 		for (i = 0; i < ac; i++) {
1039 			if ((r = sshbuf_putf(command, "%s%s",
1040 			    i ? " " : "", av[i])) != 0)
1041 				fatal("%s: buffer error: %s",
1042 				    __func__, ssh_err(r));
1043 		}
1044 	}
1045 
1046 	/*
1047 	 * Initialize "log" output.  Since we are the client all output
1048 	 * goes to stderr unless otherwise specified by -y or -E.
1049 	 */
1050 	if (use_syslog && logfile != NULL)
1051 		fatal("Can't specify both -y and -E");
1052 	if (logfile != NULL)
1053 		log_redirect_stderr_to(logfile);
1054 	log_init(argv0,
1055 	    options.log_level == SYSLOG_LEVEL_NOT_SET ?
1056 	    SYSLOG_LEVEL_INFO : options.log_level,
1057 	    options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1058 	    SYSLOG_FACILITY_USER : options.log_facility,
1059 	    !use_syslog);
1060 
1061 	if (debug_flag)
1062 		logit("%s, %s", SSH_VERSION,
1063 #ifdef WITH_OPENSSL
1064 		    SSLeay_version(SSLEAY_VERSION)
1065 #else
1066 		    "without OpenSSL"
1067 #endif
1068 		);
1069 
1070 	/* Parse the configuration files */
1071 	process_config_files(host_arg, pw, 0);
1072 
1073 	/* Hostname canonicalisation needs a few options filled. */
1074 	fill_default_options_for_canonicalization(&options);
1075 
1076 	/* If the user has replaced the hostname then take it into use now */
1077 	if (options.hostname != NULL) {
1078 		/* NB. Please keep in sync with readconf.c:match_cfg_line() */
1079 		cp = percent_expand(options.hostname,
1080 		    "h", host, (char *)NULL);
1081 		free(host);
1082 		host = cp;
1083 		free(options.hostname);
1084 		options.hostname = xstrdup(host);
1085 	}
1086 
1087 	/* Don't lowercase addresses, they will be explicitly canonicalised */
1088 	if ((was_addr = is_addr(host)) == 0)
1089 		lowercase(host);
1090 
1091 	/*
1092 	 * Try to canonicalize if requested by configuration or the
1093 	 * hostname is an address.
1094 	 */
1095 	if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
1096 		addrs = resolve_canonicalize(&host, options.port);
1097 
1098 	/*
1099 	 * If CanonicalizePermittedCNAMEs have been specified but
1100 	 * other canonicalization did not happen (by not being requested
1101 	 * or by failing with fallback) then the hostname may still be changed
1102 	 * as a result of CNAME following.
1103 	 *
1104 	 * Try to resolve the bare hostname name using the system resolver's
1105 	 * usual search rules and then apply the CNAME follow rules.
1106 	 *
1107 	 * Skip the lookup if a ProxyCommand is being used unless the user
1108 	 * has specifically requested canonicalisation for this case via
1109 	 * CanonicalizeHostname=always
1110 	 */
1111 	direct = option_clear_or_none(options.proxy_command) &&
1112 	    options.jump_host == NULL;
1113 	if (addrs == NULL && options.num_permitted_cnames != 0 && (direct ||
1114 	    options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1115 		if ((addrs = resolve_host(host, options.port,
1116 		    direct, cname, sizeof(cname))) == NULL) {
1117 			/* Don't fatal proxied host names not in the DNS */
1118 			if (direct)
1119 				cleanup_exit(255); /* logged in resolve_host */
1120 		} else
1121 			check_follow_cname(direct, &host, cname);
1122 	}
1123 
1124 	/*
1125 	 * If canonicalisation is enabled then re-parse the configuration
1126 	 * files as new stanzas may match.
1127 	 */
1128 	if (options.canonicalize_hostname != 0) {
1129 		debug("Re-reading configuration after hostname "
1130 		    "canonicalisation");
1131 		free(options.hostname);
1132 		options.hostname = xstrdup(host);
1133 		process_config_files(host_arg, pw, 1);
1134 		/*
1135 		 * Address resolution happens early with canonicalisation
1136 		 * enabled and the port number may have changed since, so
1137 		 * reset it in address list
1138 		 */
1139 		if (addrs != NULL && options.port > 0)
1140 			set_addrinfo_port(addrs, options.port);
1141 	}
1142 
1143 	/* Fill configuration defaults. */
1144 	fill_default_options(&options);
1145 
1146 	/*
1147 	 * If ProxyJump option specified, then construct a ProxyCommand now.
1148 	 */
1149 	if (options.jump_host != NULL) {
1150 		char port_s[8];
1151 		const char *sshbin = argv0;
1152 
1153 		/*
1154 		 * Try to use SSH indicated by argv[0], but fall back to
1155 		 * "ssh" if it appears unavailable.
1156 		 */
1157 		if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
1158 			sshbin = "ssh";
1159 
1160 		/* Consistency check */
1161 		if (options.proxy_command != NULL)
1162 			fatal("inconsistent options: ProxyCommand+ProxyJump");
1163 		/* Never use FD passing for ProxyJump */
1164 		options.proxy_use_fdpass = 0;
1165 		snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
1166 		xasprintf(&options.proxy_command,
1167 		    "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
1168 		    sshbin,
1169 		    /* Optional "-l user" argument if jump_user set */
1170 		    options.jump_user == NULL ? "" : " -l ",
1171 		    options.jump_user == NULL ? "" : options.jump_user,
1172 		    /* Optional "-p port" argument if jump_port set */
1173 		    options.jump_port <= 0 ? "" : " -p ",
1174 		    options.jump_port <= 0 ? "" : port_s,
1175 		    /* Optional additional jump hosts ",..." */
1176 		    options.jump_extra == NULL ? "" : " -J ",
1177 		    options.jump_extra == NULL ? "" : options.jump_extra,
1178 		    /* Optional "-F" argumment if -F specified */
1179 		    config == NULL ? "" : " -F ",
1180 		    config == NULL ? "" : config,
1181 		    /* Optional "-v" arguments if -v set */
1182 		    debug_flag ? " -" : "",
1183 		    debug_flag, "vvv",
1184 		    /* Mandatory hostname */
1185 		    options.jump_host);
1186 		debug("Setting implicit ProxyCommand from ProxyJump: %s",
1187 		    options.proxy_command);
1188 	}
1189 
1190 	if (options.port == 0)
1191 		options.port = default_ssh_port();
1192 	channel_set_af(ssh, options.address_family);
1193 
1194 	/* Tidy and check options */
1195 	if (options.host_key_alias != NULL)
1196 		lowercase(options.host_key_alias);
1197 	if (options.proxy_command != NULL &&
1198 	    strcmp(options.proxy_command, "-") == 0 &&
1199 	    options.proxy_use_fdpass)
1200 		fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1201 	if (options.control_persist &&
1202 	    options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1203 		debug("UpdateHostKeys=ask is incompatible with ControlPersist; "
1204 		    "disabling");
1205 		options.update_hostkeys = 0;
1206 	}
1207 	if (options.connection_attempts <= 0)
1208 		fatal("Invalid number of ConnectionAttempts");
1209 
1210 	if (sshbuf_len(command) != 0 && options.remote_command != NULL)
1211 		fatal("Cannot execute command-line and remote command.");
1212 
1213 	/* Cannot fork to background if no command. */
1214 	if (fork_after_authentication_flag && sshbuf_len(command) == 0 &&
1215 	    options.remote_command == NULL && !no_shell_flag)
1216 		fatal("Cannot fork into background without a command "
1217 		    "to execute.");
1218 
1219 	/* reinit */
1220 	log_init(argv0, options.log_level, options.log_facility, !use_syslog);
1221 
1222 	if (options.request_tty == REQUEST_TTY_YES ||
1223 	    options.request_tty == REQUEST_TTY_FORCE)
1224 		tty_flag = 1;
1225 
1226 	/* Allocate a tty by default if no command specified. */
1227 	if (sshbuf_len(command) == 0 && options.remote_command == NULL)
1228 		tty_flag = options.request_tty != REQUEST_TTY_NO;
1229 
1230 	/* Force no tty */
1231 	if (options.request_tty == REQUEST_TTY_NO ||
1232 	    (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
1233 		tty_flag = 0;
1234 	/* Do not allocate a tty if stdin is not a tty. */
1235 	if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
1236 	    options.request_tty != REQUEST_TTY_FORCE) {
1237 		if (tty_flag)
1238 			logit("Pseudo-terminal will not be allocated because "
1239 			    "stdin is not a terminal.");
1240 		tty_flag = 0;
1241 	}
1242 
1243 	if (options.user == NULL)
1244 		options.user = xstrdup(pw->pw_name);
1245 
1246 	/* Set up strings used to percent_expand() arguments */
1247 	if (gethostname(thishost, sizeof(thishost)) == -1)
1248 		fatal("gethostname: %s", strerror(errno));
1249 	strlcpy(shorthost, thishost, sizeof(shorthost));
1250 	shorthost[strcspn(thishost, ".")] = '\0';
1251 	snprintf(portstr, sizeof(portstr), "%d", options.port);
1252 	snprintf(uidstr, sizeof(uidstr), "%llu",
1253 	    (unsigned long long)pw->pw_uid);
1254 
1255 	if ((md = ssh_digest_start(SSH_DIGEST_SHA1)) == NULL ||
1256 	    ssh_digest_update(md, thishost, strlen(thishost)) < 0 ||
1257 	    ssh_digest_update(md, host, strlen(host)) < 0 ||
1258 	    ssh_digest_update(md, portstr, strlen(portstr)) < 0 ||
1259 	    ssh_digest_update(md, options.user, strlen(options.user)) < 0 ||
1260 	    ssh_digest_final(md, conn_hash, sizeof(conn_hash)) < 0)
1261 		fatal("%s: mux digest failed", __func__);
1262 	ssh_digest_free(md);
1263 	conn_hash_hex = tohex(conn_hash, ssh_digest_bytes(SSH_DIGEST_SHA1));
1264 
1265 	/*
1266 	 * Expand tokens in arguments. NB. LocalCommand is expanded later,
1267 	 * after port-forwarding is set up, so it may pick up any local
1268 	 * tunnel interface name allocated.
1269 	 */
1270 	if (options.remote_command != NULL) {
1271 		debug3("expanding RemoteCommand: %s", options.remote_command);
1272 		cp = options.remote_command;
1273 		options.remote_command = percent_expand(cp,
1274 		    "C", conn_hash_hex,
1275 		    "L", shorthost,
1276 		    "d", pw->pw_dir,
1277 		    "h", host,
1278 		    "i", uidstr,
1279 		    "l", thishost,
1280 		    "n", host_arg,
1281 		    "p", portstr,
1282 		    "r", options.user,
1283 		    "u", pw->pw_name,
1284 		    (char *)NULL);
1285 		debug3("expanded RemoteCommand: %s", options.remote_command);
1286 		free(cp);
1287 		if ((r = sshbuf_put(command, options.remote_command,
1288 		    strlen(options.remote_command))) != 0)
1289 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
1290 	}
1291 
1292 	if (options.control_path != NULL) {
1293 		cp = tilde_expand_filename(options.control_path, getuid());
1294 		free(options.control_path);
1295 		options.control_path = percent_expand(cp,
1296 		    "C", conn_hash_hex,
1297 		    "L", shorthost,
1298 		    "h", host,
1299 		    "i", uidstr,
1300 		    "l", thishost,
1301 		    "n", host_arg,
1302 		    "p", portstr,
1303 		    "r", options.user,
1304 		    "u", pw->pw_name,
1305 		    "i", uidstr,
1306 		    (char *)NULL);
1307 		free(cp);
1308 	}
1309 
1310 	if (config_test) {
1311 		dump_client_config(&options, host);
1312 		exit(0);
1313 	}
1314 
1315 	if (muxclient_command != 0 && options.control_path == NULL)
1316 		fatal("No ControlPath specified for \"-O\" command");
1317 	if (options.control_path != NULL) {
1318 		int sock;
1319 		if ((sock = muxclient(options.control_path)) >= 0) {
1320 			ssh_packet_set_connection(ssh, sock, sock);
1321 			packet_set_mux();
1322 			goto skip_connect;
1323 		}
1324 	}
1325 
1326 	/*
1327 	 * If hostname canonicalisation was not enabled, then we may not
1328 	 * have yet resolved the hostname. Do so now.
1329 	 */
1330 	if (addrs == NULL && options.proxy_command == NULL) {
1331 		debug2("resolving \"%s\" port %d", host, options.port);
1332 		if ((addrs = resolve_host(host, options.port, 1,
1333 		    cname, sizeof(cname))) == NULL)
1334 			cleanup_exit(255); /* resolve_host logs the error */
1335 	}
1336 
1337 	timeout_ms = options.connection_timeout * 1000;
1338 
1339 	/* Open a connection to the remote host. */
1340 	if (ssh_connect(ssh, host, addrs, &hostaddr, options.port,
1341 	    options.address_family, options.connection_attempts,
1342 	    &timeout_ms, options.tcp_keep_alive) != 0)
1343 		exit(255);
1344 
1345 	if (addrs != NULL)
1346 		freeaddrinfo(addrs);
1347 
1348 	packet_set_timeout(options.server_alive_interval,
1349 	    options.server_alive_count_max);
1350 
1351 	ssh = active_state; /* XXX */
1352 
1353 	if (timeout_ms > 0)
1354 		debug3("timeout: %d ms remain after connect", timeout_ms);
1355 
1356 	/*
1357 	 * If we successfully made the connection and we have hostbased auth
1358 	 * enabled, load the public keys so we can later use the ssh-keysign
1359 	 * helper to sign challenges.
1360 	 */
1361 	sensitive_data.nkeys = 0;
1362 	sensitive_data.keys = NULL;
1363 	if (options.hostbased_authentication) {
1364 		sensitive_data.nkeys = 10;
1365 		sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1366 		    sizeof(struct sshkey));
1367 
1368 		/* XXX check errors? */
1369 #define L_PUBKEY(p,o) do { \
1370 	if ((o) >= sensitive_data.nkeys) \
1371 		fatal("%s pubkey out of array bounds", __func__); \
1372 	check_load(sshkey_load_public(p, &(sensitive_data.keys[o]), NULL), \
1373 	    p, "pubkey"); \
1374 } while (0)
1375 #define L_CERT(p,o) do { \
1376 	if ((o) >= sensitive_data.nkeys) \
1377 		fatal("%s cert out of array bounds", __func__); \
1378 	check_load(sshkey_load_cert(p, &(sensitive_data.keys[o])), p, "cert"); \
1379 } while (0)
1380 
1381 		if (options.hostbased_authentication == 1) {
1382 			L_CERT(_PATH_HOST_ECDSA_KEY_FILE, 0);
1383 			L_CERT(_PATH_HOST_ED25519_KEY_FILE, 1);
1384 			L_CERT(_PATH_HOST_RSA_KEY_FILE, 2);
1385 			L_CERT(_PATH_HOST_DSA_KEY_FILE, 3);
1386 			L_PUBKEY(_PATH_HOST_ECDSA_KEY_FILE, 4);
1387 			L_PUBKEY(_PATH_HOST_ED25519_KEY_FILE, 5);
1388 			L_PUBKEY(_PATH_HOST_RSA_KEY_FILE, 6);
1389 			L_PUBKEY(_PATH_HOST_DSA_KEY_FILE, 7);
1390 			L_CERT(_PATH_HOST_XMSS_KEY_FILE, 8);
1391 			L_PUBKEY(_PATH_HOST_XMSS_KEY_FILE, 9);
1392 		}
1393 	}
1394 
1395 	/* Create ~/.ssh * directory if it doesn't already exist. */
1396 	if (config == NULL) {
1397 		r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1398 		    strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1399 		if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) < 0)
1400 			if (mkdir(buf, 0700) < 0)
1401 				error("Could not create directory '%.200s'.",
1402 				    buf);
1403 	}
1404 
1405 	/* load options.identity_files */
1406 	load_public_identity_files(pw);
1407 
1408 	/* optionally set the SSH_AUTHSOCKET_ENV_NAME variable */
1409 	if (options.identity_agent &&
1410 	    strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
1411 		if (strcmp(options.identity_agent, "none") == 0) {
1412 			unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1413 		} else {
1414 			p = tilde_expand_filename(options.identity_agent,
1415 			    getuid());
1416 			cp = percent_expand(p,
1417 			    "d", pw->pw_dir,
1418 			    "h", host,
1419 			    "i", uidstr,
1420 			    "l", thishost,
1421 			    "r", options.user,
1422 			    "u", pw->pw_name,
1423 			    (char *)NULL);
1424 			free(p);
1425 			/*
1426 			 * If identity_agent represents an environment variable
1427 			 * then recheck that it is valid (since processing with
1428 			 * percent_expand() may have changed it) and substitute
1429 			 * its value.
1430 			 */
1431 			if (cp[0] == '$') {
1432 				if (!valid_env_name(cp + 1)) {
1433 					fatal("Invalid IdentityAgent "
1434 					    "environment variable name %s", cp);
1435 				}
1436 				if ((p = getenv(cp + 1)) == NULL)
1437 					unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1438 				else
1439 					setenv(SSH_AUTHSOCKET_ENV_NAME, p, 1);
1440 			} else {
1441 				/* identity_agent specifies a path directly */
1442 				setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
1443 			}
1444 			free(cp);
1445 		}
1446 	}
1447 
1448 	/* Expand ~ in known host file names. */
1449 	tilde_expand_paths(options.system_hostfiles,
1450 	    options.num_system_hostfiles);
1451 	tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1452 
1453 	signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1454 	signal(SIGCHLD, main_sigchld_handler);
1455 
1456 	/* Log into the remote system.  Never returns if the login fails. */
1457 	ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr,
1458 	    options.port, pw, timeout_ms);
1459 
1460 	if (packet_connection_is_on_socket()) {
1461 		verbose("Authenticated to %s ([%s]:%d).", host,
1462 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1463 	} else {
1464 		verbose("Authenticated to %s (via proxy).", host);
1465 	}
1466 
1467 	/* We no longer need the private host keys.  Clear them now. */
1468 	if (sensitive_data.nkeys != 0) {
1469 		for (i = 0; i < sensitive_data.nkeys; i++) {
1470 			if (sensitive_data.keys[i] != NULL) {
1471 				/* Destroys contents safely */
1472 				debug3("clear hostkey %d", i);
1473 				sshkey_free(sensitive_data.keys[i]);
1474 				sensitive_data.keys[i] = NULL;
1475 			}
1476 		}
1477 		free(sensitive_data.keys);
1478 	}
1479 	for (i = 0; i < options.num_identity_files; i++) {
1480 		free(options.identity_files[i]);
1481 		options.identity_files[i] = NULL;
1482 		if (options.identity_keys[i]) {
1483 			sshkey_free(options.identity_keys[i]);
1484 			options.identity_keys[i] = NULL;
1485 		}
1486 	}
1487 	for (i = 0; i < options.num_certificate_files; i++) {
1488 		free(options.certificate_files[i]);
1489 		options.certificate_files[i] = NULL;
1490 	}
1491 
1492  skip_connect:
1493 	exit_status = ssh_session2(ssh, pw);
1494 	packet_close();
1495 
1496 	if (options.control_path != NULL && muxserver_sock != -1)
1497 		unlink(options.control_path);
1498 
1499 	/* Kill ProxyCommand if it is running. */
1500 	ssh_kill_proxy_command();
1501 
1502 	return exit_status;
1503 }
1504 
1505 static void
1506 control_persist_detach(void)
1507 {
1508 	pid_t pid;
1509 	int devnull, keep_stderr;
1510 
1511 	debug("%s: backgrounding master process", __func__);
1512 
1513 	/*
1514 	 * master (current process) into the background, and make the
1515 	 * foreground process a client of the backgrounded master.
1516 	 */
1517 	switch ((pid = fork())) {
1518 	case -1:
1519 		fatal("%s: fork: %s", __func__, strerror(errno));
1520 	case 0:
1521 		/* Child: master process continues mainloop */
1522 		break;
1523 	default:
1524 		/* Parent: set up mux slave to connect to backgrounded master */
1525 		debug2("%s: background process is %ld", __func__, (long)pid);
1526 		stdin_null_flag = ostdin_null_flag;
1527 		options.request_tty = orequest_tty;
1528 		tty_flag = otty_flag;
1529 		close(muxserver_sock);
1530 		muxserver_sock = -1;
1531 		options.control_master = SSHCTL_MASTER_NO;
1532 		muxclient(options.control_path);
1533 		/* muxclient() doesn't return on success. */
1534 		fatal("Failed to connect to new control master");
1535 	}
1536 	if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1537 		error("%s: open(\"/dev/null\"): %s", __func__,
1538 		    strerror(errno));
1539 	} else {
1540 		keep_stderr = log_is_on_stderr() && debug_flag;
1541 		if (dup2(devnull, STDIN_FILENO) == -1 ||
1542 		    dup2(devnull, STDOUT_FILENO) == -1 ||
1543 		    (!keep_stderr && dup2(devnull, STDERR_FILENO) == -1))
1544 			error("%s: dup2: %s", __func__, strerror(errno));
1545 		if (devnull > STDERR_FILENO)
1546 			close(devnull);
1547 	}
1548 	daemon(1, 1);
1549 	setproctitle("%s [mux]", options.control_path);
1550 }
1551 
1552 /* Do fork() after authentication. Used by "ssh -f" */
1553 static void
1554 fork_postauth(void)
1555 {
1556 	if (need_controlpersist_detach)
1557 		control_persist_detach();
1558 	debug("forking to background");
1559 	fork_after_authentication_flag = 0;
1560 	if (daemon(1, 1) < 0)
1561 		fatal("daemon() failed: %.200s", strerror(errno));
1562 }
1563 
1564 /* Callback for remote forward global requests */
1565 static void
1566 ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
1567 {
1568 	struct Forward *rfwd = (struct Forward *)ctxt;
1569 
1570 	/* XXX verbose() on failure? */
1571 	debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1572 	    type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1573 	    rfwd->listen_path ? rfwd->listen_path :
1574 	    rfwd->listen_host ? rfwd->listen_host : "",
1575 	    (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1576 	    rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1577 	    rfwd->connect_host, rfwd->connect_port);
1578 	if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1579 		if (type == SSH2_MSG_REQUEST_SUCCESS) {
1580 			rfwd->allocated_port = packet_get_int();
1581 			logit("Allocated port %u for remote forward to %s:%d",
1582 			    rfwd->allocated_port,
1583 			    rfwd->connect_host, rfwd->connect_port);
1584 			channel_update_permission(ssh,
1585 			    rfwd->handle, rfwd->allocated_port);
1586 		} else {
1587 			channel_update_permission(ssh, rfwd->handle, -1);
1588 		}
1589 	}
1590 
1591 	if (type == SSH2_MSG_REQUEST_FAILURE) {
1592 		if (options.exit_on_forward_failure) {
1593 			if (rfwd->listen_path != NULL)
1594 				fatal("Error: remote port forwarding failed "
1595 				    "for listen path %s", rfwd->listen_path);
1596 			else
1597 				fatal("Error: remote port forwarding failed "
1598 				    "for listen port %d", rfwd->listen_port);
1599 		} else {
1600 			if (rfwd->listen_path != NULL)
1601 				logit("Warning: remote port forwarding failed "
1602 				    "for listen path %s", rfwd->listen_path);
1603 			else
1604 				logit("Warning: remote port forwarding failed "
1605 				    "for listen port %d", rfwd->listen_port);
1606 		}
1607 	}
1608 	if (++remote_forward_confirms_received == options.num_remote_forwards) {
1609 		debug("All remote forwarding requests processed");
1610 		if (fork_after_authentication_flag)
1611 			fork_postauth();
1612 	}
1613 }
1614 
1615 static void
1616 client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
1617 {
1618 	debug("stdio forwarding: done");
1619 	cleanup_exit(0);
1620 }
1621 
1622 static void
1623 ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1624 {
1625 	if (!success)
1626 		fatal("stdio forwarding failed");
1627 }
1628 
1629 static void
1630 ssh_init_stdio_forwarding(struct ssh *ssh)
1631 {
1632 	Channel *c;
1633 	int in, out;
1634 
1635 	if (options.stdio_forward_host == NULL)
1636 		return;
1637 
1638 	debug3("%s: %s:%d", __func__, options.stdio_forward_host,
1639 	    options.stdio_forward_port);
1640 
1641 	if ((in = dup(STDIN_FILENO)) < 0 ||
1642 	    (out = dup(STDOUT_FILENO)) < 0)
1643 		fatal("channel_connect_stdio_fwd: dup() in/out failed");
1644 	if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
1645 	    options.stdio_forward_port, in, out)) == NULL)
1646 		fatal("%s: channel_connect_stdio_fwd failed", __func__);
1647 	channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
1648 	channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
1649 }
1650 
1651 static void
1652 ssh_init_forwarding(struct ssh *ssh, char **ifname)
1653 {
1654 	int success = 0;
1655 	int i;
1656 
1657 	/* Initiate local TCP/IP port forwardings. */
1658 	for (i = 0; i < options.num_local_forwards; i++) {
1659 		debug("Local connections to %.200s:%d forwarded to remote "
1660 		    "address %.200s:%d",
1661 		    (options.local_forwards[i].listen_path != NULL) ?
1662 		    options.local_forwards[i].listen_path :
1663 		    (options.local_forwards[i].listen_host == NULL) ?
1664 		    (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1665 		    options.local_forwards[i].listen_host,
1666 		    options.local_forwards[i].listen_port,
1667 		    (options.local_forwards[i].connect_path != NULL) ?
1668 		    options.local_forwards[i].connect_path :
1669 		    options.local_forwards[i].connect_host,
1670 		    options.local_forwards[i].connect_port);
1671 		success += channel_setup_local_fwd_listener(ssh,
1672 		    &options.local_forwards[i], &options.fwd_opts);
1673 	}
1674 	if (i > 0 && success != i && options.exit_on_forward_failure)
1675 		fatal("Could not request local forwarding.");
1676 	if (i > 0 && success == 0)
1677 		error("Could not request local forwarding.");
1678 
1679 	/* Initiate remote TCP/IP port forwardings. */
1680 	for (i = 0; i < options.num_remote_forwards; i++) {
1681 		debug("Remote connections from %.200s:%d forwarded to "
1682 		    "local address %.200s:%d",
1683 		    (options.remote_forwards[i].listen_path != NULL) ?
1684 		    options.remote_forwards[i].listen_path :
1685 		    (options.remote_forwards[i].listen_host == NULL) ?
1686 		    "LOCALHOST" : options.remote_forwards[i].listen_host,
1687 		    options.remote_forwards[i].listen_port,
1688 		    (options.remote_forwards[i].connect_path != NULL) ?
1689 		    options.remote_forwards[i].connect_path :
1690 		    options.remote_forwards[i].connect_host,
1691 		    options.remote_forwards[i].connect_port);
1692 		options.remote_forwards[i].handle =
1693 		    channel_request_remote_forwarding(ssh,
1694 		    &options.remote_forwards[i]);
1695 		if (options.remote_forwards[i].handle < 0) {
1696 			if (options.exit_on_forward_failure)
1697 				fatal("Could not request remote forwarding.");
1698 			else
1699 				logit("Warning: Could not request remote "
1700 				    "forwarding.");
1701 		} else {
1702 			client_register_global_confirm(
1703 			    ssh_confirm_remote_forward,
1704 			    &options.remote_forwards[i]);
1705 		}
1706 	}
1707 
1708 	/* Initiate tunnel forwarding. */
1709 	if (options.tun_open != SSH_TUNMODE_NO) {
1710 		if ((*ifname = client_request_tun_fwd(ssh,
1711 		    options.tun_open, options.tun_local,
1712 		    options.tun_remote)) == NULL) {
1713 			if (options.exit_on_forward_failure)
1714 				fatal("Could not request tunnel forwarding.");
1715 			else
1716 				error("Could not request tunnel forwarding.");
1717 		}
1718 	}
1719 }
1720 
1721 static void
1722 check_agent_present(void)
1723 {
1724 	int r;
1725 
1726 	if (options.forward_agent) {
1727 		/* Clear agent forwarding if we don't have an agent. */
1728 		if ((r = ssh_get_authentication_socket(NULL)) != 0) {
1729 			options.forward_agent = 0;
1730 			if (r != SSH_ERR_AGENT_NOT_PRESENT)
1731 				debug("ssh_get_authentication_socket: %s",
1732 				    ssh_err(r));
1733 		}
1734 	}
1735 }
1736 
1737 static void
1738 ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
1739 {
1740 	extern char **environ;
1741 	const char *display;
1742 	int interactive = tty_flag;
1743 	char *proto = NULL, *data = NULL;
1744 
1745 	if (!success)
1746 		return; /* No need for error message, channels code sens one */
1747 
1748 	display = getenv("DISPLAY");
1749 	if (display == NULL && options.forward_x11)
1750 		debug("X11 forwarding requested but DISPLAY not set");
1751 	if (options.forward_x11 && client_x11_get_proto(ssh, display,
1752 	    options.xauth_location, options.forward_x11_trusted,
1753 	    options.forward_x11_timeout, &proto, &data) == 0) {
1754 		/* Request forwarding with authentication spoofing. */
1755 		debug("Requesting X11 forwarding with authentication "
1756 		    "spoofing.");
1757 		x11_request_forwarding_with_spoofing(ssh, id, display, proto,
1758 		    data, 1);
1759 		client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
1760 		/* XXX exit_on_forward_failure */
1761 		interactive = 1;
1762 	}
1763 
1764 	check_agent_present();
1765 	if (options.forward_agent) {
1766 		debug("Requesting authentication agent forwarding.");
1767 		channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1768 		packet_send();
1769 	}
1770 
1771 	/* Tell the packet module whether this is an interactive session. */
1772 	packet_set_interactive(interactive,
1773 	    options.ip_qos_interactive, options.ip_qos_bulk);
1774 
1775 	client_session2_setup(ssh, id, tty_flag, subsystem_flag, getenv("TERM"),
1776 	    NULL, fileno(stdin), command, environ);
1777 }
1778 
1779 /* open new channel for a session */
1780 static int
1781 ssh_session2_open(struct ssh *ssh)
1782 {
1783 	Channel *c;
1784 	int window, packetmax, in, out, err;
1785 
1786 	if (stdin_null_flag) {
1787 		in = open(_PATH_DEVNULL, O_RDONLY);
1788 	} else {
1789 		in = dup(STDIN_FILENO);
1790 	}
1791 	out = dup(STDOUT_FILENO);
1792 	err = dup(STDERR_FILENO);
1793 
1794 	if (in < 0 || out < 0 || err < 0)
1795 		fatal("dup() in/out/err failed");
1796 
1797 	/* enable nonblocking unless tty */
1798 	if (!isatty(in))
1799 		set_nonblock(in);
1800 	if (!isatty(out))
1801 		set_nonblock(out);
1802 	if (!isatty(err))
1803 		set_nonblock(err);
1804 
1805 	window = CHAN_SES_WINDOW_DEFAULT;
1806 	packetmax = CHAN_SES_PACKET_DEFAULT;
1807 	if (tty_flag) {
1808 		window >>= 1;
1809 		packetmax >>= 1;
1810 	}
1811 	c = channel_new(ssh,
1812 	    "session", SSH_CHANNEL_OPENING, in, out, err,
1813 	    window, packetmax, CHAN_EXTENDED_WRITE,
1814 	    "client-session", /*nonblock*/0);
1815 
1816 	debug3("%s: channel_new: %d", __func__, c->self);
1817 
1818 	channel_send_open(ssh, c->self);
1819 	if (!no_shell_flag)
1820 		channel_register_open_confirm(ssh, c->self,
1821 		    ssh_session2_setup, NULL);
1822 
1823 	return c->self;
1824 }
1825 
1826 static int
1827 ssh_session2(struct ssh *ssh, struct passwd *pw)
1828 {
1829 	int devnull, id = -1;
1830 	char *cp, *tun_fwd_ifname = NULL;
1831 
1832 	/* XXX should be pre-session */
1833 	if (!options.control_persist)
1834 		ssh_init_stdio_forwarding(ssh);
1835 
1836 	ssh_init_forwarding(ssh, &tun_fwd_ifname);
1837 
1838 	if (options.local_command != NULL) {
1839 		debug3("expanding LocalCommand: %s", options.local_command);
1840 		cp = options.local_command;
1841 		options.local_command = percent_expand(cp,
1842 		    "C", conn_hash_hex,
1843 		    "L", shorthost,
1844 		    "d", pw->pw_dir,
1845 		    "h", host,
1846 		    "i", uidstr,
1847 		    "l", thishost,
1848 		    "n", host_arg,
1849 		    "p", portstr,
1850 		    "r", options.user,
1851 		    "u", pw->pw_name,
1852 		    "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
1853 		    (char *)NULL);
1854 		debug3("expanded LocalCommand: %s", options.local_command);
1855 		free(cp);
1856 	}
1857 
1858 	/* Start listening for multiplex clients */
1859 	if (!packet_get_mux())
1860 		muxserver_listen(ssh);
1861 
1862 	/*
1863 	 * If we are in control persist mode and have a working mux listen
1864 	 * socket, then prepare to background ourselves and have a foreground
1865 	 * client attach as a control slave.
1866 	 * NB. we must save copies of the flags that we override for
1867 	 * the backgrounding, since we defer attachment of the slave until
1868 	 * after the connection is fully established (in particular,
1869 	 * async rfwd replies have been received for ExitOnForwardFailure).
1870 	 */
1871 	if (options.control_persist && muxserver_sock != -1) {
1872 		ostdin_null_flag = stdin_null_flag;
1873 		ono_shell_flag = no_shell_flag;
1874 		orequest_tty = options.request_tty;
1875 		otty_flag = tty_flag;
1876 		stdin_null_flag = 1;
1877 		no_shell_flag = 1;
1878 		tty_flag = 0;
1879 		if (!fork_after_authentication_flag)
1880 			need_controlpersist_detach = 1;
1881 		fork_after_authentication_flag = 1;
1882 	}
1883 	/*
1884 	 * ControlPersist mux listen socket setup failed, attempt the
1885 	 * stdio forward setup that we skipped earlier.
1886 	 */
1887 	if (options.control_persist && muxserver_sock == -1)
1888 		ssh_init_stdio_forwarding(ssh);
1889 
1890 	if (!no_shell_flag)
1891 		id = ssh_session2_open(ssh);
1892 	else {
1893 		packet_set_interactive(
1894 		    options.control_master == SSHCTL_MASTER_NO,
1895 		    options.ip_qos_interactive, options.ip_qos_bulk);
1896 	}
1897 
1898 	/* If we don't expect to open a new session, then disallow it */
1899 	if (options.control_master == SSHCTL_MASTER_NO &&
1900 	    (datafellows & SSH_NEW_OPENSSH)) {
1901 		debug("Requesting no-more-sessions@openssh.com");
1902 		packet_start(SSH2_MSG_GLOBAL_REQUEST);
1903 		packet_put_cstring("no-more-sessions@openssh.com");
1904 		packet_put_char(0);
1905 		packet_send();
1906 	}
1907 
1908 	/* Execute a local command */
1909 	if (options.local_command != NULL &&
1910 	    options.permit_local_command)
1911 		ssh_local_cmd(options.local_command);
1912 
1913 	/*
1914 	 * stdout is now owned by the session channel; clobber it here
1915 	 * so future channel closes are propagated to the local fd.
1916 	 * NB. this can only happen after LocalCommand has completed,
1917 	 * as it may want to write to stdout.
1918 	 */
1919 	if (!need_controlpersist_detach) {
1920 		if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
1921 			error("%s: open %s: %s", __func__,
1922 			    _PATH_DEVNULL, strerror(errno));
1923 		if (dup2(devnull, STDOUT_FILENO) < 0)
1924 			fatal("%s: dup2() stdout failed", __func__);
1925 		if (devnull > STDERR_FILENO)
1926 			close(devnull);
1927 	}
1928 
1929 	/*
1930 	 * If requested and we are not interested in replies to remote
1931 	 * forwarding requests, then let ssh continue in the background.
1932 	 */
1933 	if (fork_after_authentication_flag) {
1934 		if (options.exit_on_forward_failure &&
1935 		    options.num_remote_forwards > 0) {
1936 			debug("deferring postauth fork until remote forward "
1937 			    "confirmation received");
1938 		} else
1939 			fork_postauth();
1940 	}
1941 
1942 	return client_loop(ssh, tty_flag, tty_flag ?
1943 	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
1944 }
1945 
1946 /* Loads all IdentityFile and CertificateFile keys */
1947 static void
1948 load_public_identity_files(struct passwd *pw)
1949 {
1950 	char *filename, *cp;
1951 	struct sshkey *public;
1952 	int i;
1953 	u_int n_ids, n_certs;
1954 	char *identity_files[SSH_MAX_IDENTITY_FILES];
1955 	struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
1956 	int identity_file_userprovided[SSH_MAX_IDENTITY_FILES];
1957 	char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
1958 	struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
1959 	int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES];
1960 #ifdef ENABLE_PKCS11
1961 	struct sshkey **keys;
1962 	int nkeys;
1963 #endif /* PKCS11 */
1964 
1965 	n_ids = n_certs = 0;
1966 	memset(identity_files, 0, sizeof(identity_files));
1967 	memset(identity_keys, 0, sizeof(identity_keys));
1968 	memset(identity_file_userprovided, 0,
1969 	    sizeof(identity_file_userprovided));
1970 	memset(certificate_files, 0, sizeof(certificate_files));
1971 	memset(certificates, 0, sizeof(certificates));
1972 	memset(certificate_file_userprovided, 0,
1973 	    sizeof(certificate_file_userprovided));
1974 
1975 #ifdef ENABLE_PKCS11
1976 	if (options.pkcs11_provider != NULL &&
1977 	    options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1978 	    (pkcs11_init(!options.batch_mode) == 0) &&
1979 	    (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
1980 	    &keys)) > 0) {
1981 		for (i = 0; i < nkeys; i++) {
1982 			if (n_ids >= SSH_MAX_IDENTITY_FILES) {
1983 				sshkey_free(keys[i]);
1984 				continue;
1985 			}
1986 			identity_keys[n_ids] = keys[i];
1987 			identity_files[n_ids] =
1988 			    xstrdup(options.pkcs11_provider); /* XXX */
1989 			n_ids++;
1990 		}
1991 		free(keys);
1992 	}
1993 #endif /* ENABLE_PKCS11 */
1994 	for (i = 0; i < options.num_identity_files; i++) {
1995 		if (n_ids >= SSH_MAX_IDENTITY_FILES ||
1996 		    strcasecmp(options.identity_files[i], "none") == 0) {
1997 			free(options.identity_files[i]);
1998 			options.identity_files[i] = NULL;
1999 			continue;
2000 		}
2001 		cp = tilde_expand_filename(options.identity_files[i], getuid());
2002 		filename = percent_expand(cp, "d", pw->pw_dir,
2003 		    "u", pw->pw_name, "l", thishost, "h", host,
2004 		    "r", options.user, (char *)NULL);
2005 		free(cp);
2006 		check_load(sshkey_load_public(filename, &public, NULL),
2007 		    filename, "pubkey");
2008 		debug("identity file %s type %d", filename,
2009 		    public ? public->type : -1);
2010 		free(options.identity_files[i]);
2011 		identity_files[n_ids] = filename;
2012 		identity_keys[n_ids] = public;
2013 		identity_file_userprovided[n_ids] =
2014 		    options.identity_file_userprovided[i];
2015 		if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2016 			continue;
2017 
2018 		/*
2019 		 * If no certificates have been explicitly listed then try
2020 		 * to add the default certificate variant too.
2021 		 */
2022 		if (options.num_certificate_files != 0)
2023 			continue;
2024 		xasprintf(&cp, "%s-cert", filename);
2025 		check_load(sshkey_load_public(cp, &public, NULL),
2026 		    filename, "pubkey");
2027 		debug("identity file %s type %d", cp,
2028 		    public ? public->type : -1);
2029 		if (public == NULL) {
2030 			free(cp);
2031 			continue;
2032 		}
2033 		if (!sshkey_is_cert(public)) {
2034 			debug("%s: key %s type %s is not a certificate",
2035 			    __func__, cp, sshkey_type(public));
2036 			sshkey_free(public);
2037 			free(cp);
2038 			continue;
2039 		}
2040 		/* NB. leave filename pointing to private key */
2041 		identity_files[n_ids] = xstrdup(filename);
2042 		identity_keys[n_ids] = public;
2043 		identity_file_userprovided[n_ids] =
2044 		    options.identity_file_userprovided[i];
2045 		n_ids++;
2046 	}
2047 
2048 	if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
2049 		fatal("%s: too many certificates", __func__);
2050 	for (i = 0; i < options.num_certificate_files; i++) {
2051 		cp = tilde_expand_filename(options.certificate_files[i],
2052 		    getuid());
2053 		filename = percent_expand(cp,
2054 		    "d", pw->pw_dir,
2055 		    "h", host,
2056 		    "i", uidstr,
2057 		    "l", thishost,
2058 		    "r", options.user,
2059 		    "u", pw->pw_name,
2060 		    (char *)NULL);
2061 		free(cp);
2062 
2063 		check_load(sshkey_load_public(filename, &public, NULL),
2064 		    filename, "certificate");
2065 		debug("certificate file %s type %d", filename,
2066 		    public ? public->type : -1);
2067 		free(options.certificate_files[i]);
2068 		options.certificate_files[i] = NULL;
2069 		if (public == NULL) {
2070 			free(filename);
2071 			continue;
2072 		}
2073 		if (!sshkey_is_cert(public)) {
2074 			debug("%s: key %s type %s is not a certificate",
2075 			    __func__, filename, sshkey_type(public));
2076 			sshkey_free(public);
2077 			free(filename);
2078 			continue;
2079 		}
2080 		certificate_files[n_certs] = filename;
2081 		certificates[n_certs] = public;
2082 		certificate_file_userprovided[n_certs] =
2083 		    options.certificate_file_userprovided[i];
2084 		++n_certs;
2085 	}
2086 
2087 	options.num_identity_files = n_ids;
2088 	memcpy(options.identity_files, identity_files, sizeof(identity_files));
2089 	memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2090 	memcpy(options.identity_file_userprovided,
2091 	    identity_file_userprovided, sizeof(identity_file_userprovided));
2092 
2093 	options.num_certificate_files = n_certs;
2094 	memcpy(options.certificate_files,
2095 	    certificate_files, sizeof(certificate_files));
2096 	memcpy(options.certificates, certificates, sizeof(certificates));
2097 	memcpy(options.certificate_file_userprovided,
2098 	    certificate_file_userprovided,
2099 	    sizeof(certificate_file_userprovided));
2100 }
2101 
2102 static void
2103 main_sigchld_handler(int sig)
2104 {
2105 	int save_errno = errno;
2106 	pid_t pid;
2107 	int status;
2108 
2109 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2110 	    (pid < 0 && errno == EINTR))
2111 		;
2112 	errno = save_errno;
2113 }
2114