xref: /openssh-portable/ssh.c (revision de1f3564)
1 /* $OpenBSD: ssh.c,v 1.520 2020/02/18 08:49:49 dtucker 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 
45 #include <sys/types.h>
46 #ifdef HAVE_SYS_STAT_H
47 # include <sys/stat.h>
48 #endif
49 #include <sys/resource.h>
50 #include <sys/ioctl.h>
51 #include <sys/socket.h>
52 #include <sys/wait.h>
53 
54 #include <ctype.h>
55 #include <errno.h>
56 #include <fcntl.h>
57 #include <netdb.h>
58 #ifdef HAVE_PATHS_H
59 #include <paths.h>
60 #endif
61 #include <pwd.h>
62 #include <signal.h>
63 #include <stdarg.h>
64 #include <stddef.h>
65 #include <stdio.h>
66 #include <stdlib.h>
67 #include <string.h>
68 #include <stdarg.h>
69 #include <unistd.h>
70 #include <limits.h>
71 #include <locale.h>
72 
73 #include <netinet/in.h>
74 #include <arpa/inet.h>
75 
76 #ifdef WITH_OPENSSL
77 #include <openssl/evp.h>
78 #include <openssl/err.h>
79 #endif
80 #include "openbsd-compat/openssl-compat.h"
81 #include "openbsd-compat/sys-queue.h"
82 
83 #include "xmalloc.h"
84 #include "ssh.h"
85 #include "ssh2.h"
86 #include "canohost.h"
87 #include "compat.h"
88 #include "cipher.h"
89 #include "digest.h"
90 #include "packet.h"
91 #include "sshbuf.h"
92 #include "channels.h"
93 #include "sshkey.h"
94 #include "authfd.h"
95 #include "authfile.h"
96 #include "pathnames.h"
97 #include "dispatch.h"
98 #include "clientloop.h"
99 #include "log.h"
100 #include "misc.h"
101 #include "readconf.h"
102 #include "sshconnect.h"
103 #include "kex.h"
104 #include "mac.h"
105 #include "sshpty.h"
106 #include "match.h"
107 #include "msg.h"
108 #include "version.h"
109 #include "ssherr.h"
110 #include "myproposal.h"
111 #include "utf8.h"
112 
113 #ifdef ENABLE_PKCS11
114 #include "ssh-pkcs11.h"
115 #endif
116 
117 extern char *__progname;
118 
119 /* Saves a copy of argv for setproctitle emulation */
120 #ifndef HAVE_SETPROCTITLE
121 static char **saved_av;
122 #endif
123 
124 /* Flag indicating whether debug mode is on.  May be set on the command line. */
125 int debug_flag = 0;
126 
127 /* Flag indicating whether a tty should be requested */
128 int tty_flag = 0;
129 
130 /* don't exec a shell */
131 int no_shell_flag = 0;
132 
133 /*
134  * Flag indicating that nothing should be read from stdin.  This can be set
135  * on the command line.
136  */
137 int stdin_null_flag = 0;
138 
139 /*
140  * Flag indicating that the current process should be backgrounded and
141  * a new slave launched in the foreground for ControlPersist.
142  */
143 int need_controlpersist_detach = 0;
144 
145 /* Copies of flags for ControlPersist foreground slave */
146 int ostdin_null_flag, ono_shell_flag, otty_flag, orequest_tty;
147 
148 /*
149  * Flag indicating that ssh should fork after authentication.  This is useful
150  * so that the passphrase can be entered manually, and then ssh goes to the
151  * background.
152  */
153 int fork_after_authentication_flag = 0;
154 
155 /*
156  * General data structure for command line options and options configurable
157  * in configuration files.  See readconf.h.
158  */
159 Options options;
160 
161 /* optional user configfile */
162 char *config = NULL;
163 
164 /*
165  * Name of the host we are connecting to.  This is the name given on the
166  * command line, or the Hostname specified for the user-supplied name in a
167  * configuration file.
168  */
169 char *host;
170 
171 /*
172  * A config can specify a path to forward, overriding SSH_AUTH_SOCK. If this is
173  * not NULL, forward the socket at this path instead.
174  */
175 char *forward_agent_sock_path = NULL;
176 
177 /* Various strings used to to percent_expand() arguments */
178 static char thishost[NI_MAXHOST], shorthost[NI_MAXHOST], portstr[NI_MAXSERV];
179 static char uidstr[32], *host_arg, *conn_hash_hex;
180 
181 /* socket address the host resolves to */
182 struct sockaddr_storage hostaddr;
183 
184 /* Private host keys. */
185 Sensitive sensitive_data;
186 
187 /* command to be executed */
188 struct sshbuf *command;
189 
190 /* Should we execute a command or invoke a subsystem? */
191 int subsystem_flag = 0;
192 
193 /* # of replies received for global requests */
194 static int remote_forward_confirms_received = 0;
195 
196 /* mux.c */
197 extern int muxserver_sock;
198 extern u_int muxclient_command;
199 
200 /* Prints a help message to the user.  This function never returns. */
201 
202 static void
203 usage(void)
204 {
205 	fprintf(stderr,
206 "usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
207 "           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
208 "           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
209 "           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
210 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
211 "           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
212 "           [-w local_tun[:remote_tun]] destination [command]\n"
213 	);
214 	exit(255);
215 }
216 
217 static int ssh_session2(struct ssh *, struct passwd *);
218 static void load_public_identity_files(struct passwd *);
219 static void main_sigchld_handler(int);
220 
221 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
222 static void
223 tilde_expand_paths(char **paths, u_int num_paths)
224 {
225 	u_int i;
226 	char *cp;
227 
228 	for (i = 0; i < num_paths; i++) {
229 		cp = tilde_expand_filename(paths[i], getuid());
230 		free(paths[i]);
231 		paths[i] = cp;
232 	}
233 }
234 
235 /*
236  * Attempt to resolve a host name / port to a set of addresses and
237  * optionally return any CNAMEs encountered along the way.
238  * Returns NULL on failure.
239  * NB. this function must operate with a options having undefined members.
240  */
241 static struct addrinfo *
242 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
243 {
244 	char strport[NI_MAXSERV];
245 	struct addrinfo hints, *res;
246 	int gaierr;
247 	LogLevel loglevel = SYSLOG_LEVEL_DEBUG1;
248 
249 	if (port <= 0)
250 		port = default_ssh_port();
251 
252 	snprintf(strport, sizeof strport, "%d", port);
253 	memset(&hints, 0, sizeof(hints));
254 	hints.ai_family = options.address_family == -1 ?
255 	    AF_UNSPEC : options.address_family;
256 	hints.ai_socktype = SOCK_STREAM;
257 	if (cname != NULL)
258 		hints.ai_flags = AI_CANONNAME;
259 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
260 		if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
261 			loglevel = SYSLOG_LEVEL_ERROR;
262 		do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
263 		    __progname, name, ssh_gai_strerror(gaierr));
264 		return NULL;
265 	}
266 	if (cname != NULL && res->ai_canonname != NULL) {
267 		if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
268 			error("%s: host \"%s\" cname \"%s\" too long (max %lu)",
269 			    __func__, name,  res->ai_canonname, (u_long)clen);
270 			if (clen > 0)
271 				*cname = '\0';
272 		}
273 	}
274 	return res;
275 }
276 
277 /* Returns non-zero if name can only be an address and not a hostname */
278 static int
279 is_addr_fast(const char *name)
280 {
281 	return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
282 	    strspn(name, "0123456789.") == strlen(name));
283 }
284 
285 /* Returns non-zero if name represents a valid, single address */
286 static int
287 is_addr(const char *name)
288 {
289 	char strport[NI_MAXSERV];
290 	struct addrinfo hints, *res;
291 
292 	if (is_addr_fast(name))
293 		return 1;
294 
295 	snprintf(strport, sizeof strport, "%u", default_ssh_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 (getaddrinfo(name, strport, &hints, &res) != 0)
302 		return 0;
303 	if (res == NULL || res->ai_next != NULL) {
304 		freeaddrinfo(res);
305 		return 0;
306 	}
307 	freeaddrinfo(res);
308 	return 1;
309 }
310 
311 /*
312  * Attempt to resolve a numeric host address / port to a single address.
313  * Returns a canonical address string.
314  * Returns NULL on failure.
315  * NB. this function must operate with a options having undefined members.
316  */
317 static struct addrinfo *
318 resolve_addr(const char *name, int port, char *caddr, size_t clen)
319 {
320 	char addr[NI_MAXHOST], strport[NI_MAXSERV];
321 	struct addrinfo hints, *res;
322 	int gaierr;
323 
324 	if (port <= 0)
325 		port = default_ssh_port();
326 	snprintf(strport, sizeof strport, "%u", port);
327 	memset(&hints, 0, sizeof(hints));
328 	hints.ai_family = options.address_family == -1 ?
329 	    AF_UNSPEC : options.address_family;
330 	hints.ai_socktype = SOCK_STREAM;
331 	hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
332 	if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
333 		debug2("%s: could not resolve name %.100s as address: %s",
334 		    __func__, name, ssh_gai_strerror(gaierr));
335 		return NULL;
336 	}
337 	if (res == NULL) {
338 		debug("%s: getaddrinfo %.100s returned no addresses",
339 		 __func__, name);
340 		return NULL;
341 	}
342 	if (res->ai_next != NULL) {
343 		debug("%s: getaddrinfo %.100s returned multiple addresses",
344 		    __func__, name);
345 		goto fail;
346 	}
347 	if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
348 	    addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
349 		debug("%s: Could not format address for name %.100s: %s",
350 		    __func__, name, ssh_gai_strerror(gaierr));
351 		goto fail;
352 	}
353 	if (strlcpy(caddr, addr, clen) >= clen) {
354 		error("%s: host \"%s\" addr \"%s\" too long (max %lu)",
355 		    __func__, name,  addr, (u_long)clen);
356 		if (clen > 0)
357 			*caddr = '\0';
358  fail:
359 		freeaddrinfo(res);
360 		return NULL;
361 	}
362 	return res;
363 }
364 
365 /*
366  * Check whether the cname is a permitted replacement for the hostname
367  * and perform the replacement if it is.
368  * NB. this function must operate with a options having undefined members.
369  */
370 static int
371 check_follow_cname(int direct, char **namep, const char *cname)
372 {
373 	int i;
374 	struct allowed_cname *rule;
375 
376 	if (*cname == '\0' || options.num_permitted_cnames == 0 ||
377 	    strcmp(*namep, cname) == 0)
378 		return 0;
379 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
380 		return 0;
381 	/*
382 	 * Don't attempt to canonicalize names that will be interpreted by
383 	 * a proxy or jump host unless the user specifically requests so.
384 	 */
385 	if (!direct &&
386 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
387 		return 0;
388 	debug3("%s: check \"%s\" CNAME \"%s\"", __func__, *namep, cname);
389 	for (i = 0; i < options.num_permitted_cnames; i++) {
390 		rule = options.permitted_cnames + i;
391 		if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
392 		    match_pattern_list(cname, rule->target_list, 1) != 1)
393 			continue;
394 		verbose("Canonicalized DNS aliased hostname "
395 		    "\"%s\" => \"%s\"", *namep, cname);
396 		free(*namep);
397 		*namep = xstrdup(cname);
398 		return 1;
399 	}
400 	return 0;
401 }
402 
403 /*
404  * Attempt to resolve the supplied hostname after applying the user's
405  * canonicalization rules. Returns the address list for the host or NULL
406  * if no name was found after canonicalization.
407  * NB. this function must operate with a options having undefined members.
408  */
409 static struct addrinfo *
410 resolve_canonicalize(char **hostp, int port)
411 {
412 	int i, direct, ndots;
413 	char *cp, *fullhost, newname[NI_MAXHOST];
414 	struct addrinfo *addrs;
415 
416 	/*
417 	 * Attempt to canonicalise addresses, regardless of
418 	 * whether hostname canonicalisation was requested
419 	 */
420 	if ((addrs = resolve_addr(*hostp, port,
421 	    newname, sizeof(newname))) != NULL) {
422 		debug2("%s: hostname %.100s is address", __func__, *hostp);
423 		if (strcasecmp(*hostp, newname) != 0) {
424 			debug2("%s: canonicalised address \"%s\" => \"%s\"",
425 			    __func__, *hostp, newname);
426 			free(*hostp);
427 			*hostp = xstrdup(newname);
428 		}
429 		return addrs;
430 	}
431 
432 	/*
433 	 * If this looks like an address but didn't parse as one, it might
434 	 * be an address with an invalid interface scope. Skip further
435 	 * attempts at canonicalisation.
436 	 */
437 	if (is_addr_fast(*hostp)) {
438 		debug("%s: hostname %.100s is an unrecognised address",
439 		    __func__, *hostp);
440 		return NULL;
441 	}
442 
443 	if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
444 		return NULL;
445 
446 	/*
447 	 * Don't attempt to canonicalize names that will be interpreted by
448 	 * a proxy unless the user specifically requests so.
449 	 */
450 	direct = option_clear_or_none(options.proxy_command) &&
451 	    options.jump_host == NULL;
452 	if (!direct &&
453 	    options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
454 		return NULL;
455 
456 	/* If domain name is anchored, then resolve it now */
457 	if ((*hostp)[strlen(*hostp) - 1] == '.') {
458 		debug3("%s: name is fully qualified", __func__);
459 		fullhost = xstrdup(*hostp);
460 		if ((addrs = resolve_host(fullhost, port, 0,
461 		    newname, sizeof(newname))) != NULL)
462 			goto found;
463 		free(fullhost);
464 		goto notfound;
465 	}
466 
467 	/* Don't apply canonicalization to sufficiently-qualified hostnames */
468 	ndots = 0;
469 	for (cp = *hostp; *cp != '\0'; cp++) {
470 		if (*cp == '.')
471 			ndots++;
472 	}
473 	if (ndots > options.canonicalize_max_dots) {
474 		debug3("%s: not canonicalizing hostname \"%s\" (max dots %d)",
475 		    __func__, *hostp, options.canonicalize_max_dots);
476 		return NULL;
477 	}
478 	/* Attempt each supplied suffix */
479 	for (i = 0; i < options.num_canonical_domains; i++) {
480 		*newname = '\0';
481 		xasprintf(&fullhost, "%s.%s.", *hostp,
482 		    options.canonical_domains[i]);
483 		debug3("%s: attempting \"%s\" => \"%s\"", __func__,
484 		    *hostp, fullhost);
485 		if ((addrs = resolve_host(fullhost, port, 0,
486 		    newname, sizeof(newname))) == NULL) {
487 			free(fullhost);
488 			continue;
489 		}
490  found:
491 		/* Remove trailing '.' */
492 		fullhost[strlen(fullhost) - 1] = '\0';
493 		/* Follow CNAME if requested */
494 		if (!check_follow_cname(direct, &fullhost, newname)) {
495 			debug("Canonicalized hostname \"%s\" => \"%s\"",
496 			    *hostp, fullhost);
497 		}
498 		free(*hostp);
499 		*hostp = fullhost;
500 		return addrs;
501 	}
502  notfound:
503 	if (!options.canonicalize_fallback_local)
504 		fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
505 	debug2("%s: host %s not found in any suffix", __func__, *hostp);
506 	return NULL;
507 }
508 
509 /*
510  * Check the result of hostkey loading, ignoring some errors and
511  * fatal()ing for others.
512  */
513 static void
514 check_load(int r, const char *path, const char *message)
515 {
516 	switch (r) {
517 	case 0:
518 		break;
519 	case SSH_ERR_INTERNAL_ERROR:
520 	case SSH_ERR_ALLOC_FAIL:
521 		fatal("load %s \"%s\": %s", message, path, ssh_err(r));
522 	case SSH_ERR_SYSTEM_ERROR:
523 		/* Ignore missing files */
524 		if (errno == ENOENT)
525 			break;
526 		/* FALLTHROUGH */
527 	default:
528 		error("load %s \"%s\": %s", message, path, ssh_err(r));
529 		break;
530 	}
531 }
532 
533 /*
534  * Read per-user configuration file.  Ignore the system wide config
535  * file if the user specifies a config file on the command line.
536  */
537 static void
538 process_config_files(const char *host_name, struct passwd *pw, int final_pass,
539     int *want_final_pass)
540 {
541 	char buf[PATH_MAX];
542 	int r;
543 
544 	if (config != NULL) {
545 		if (strcasecmp(config, "none") != 0 &&
546 		    !read_config_file(config, pw, host, host_name, &options,
547 		    SSHCONF_USERCONF | (final_pass ? SSHCONF_FINAL : 0),
548 		    want_final_pass))
549 			fatal("Can't open user config file %.100s: "
550 			    "%.100s", config, strerror(errno));
551 	} else {
552 		r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
553 		    _PATH_SSH_USER_CONFFILE);
554 		if (r > 0 && (size_t)r < sizeof(buf))
555 			(void)read_config_file(buf, pw, host, host_name,
556 			    &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
557 			    (final_pass ? SSHCONF_FINAL : 0), want_final_pass);
558 
559 		/* Read systemwide configuration file after user config. */
560 		(void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
561 		    host, host_name, &options,
562 		    final_pass ? SSHCONF_FINAL : 0, want_final_pass);
563 	}
564 }
565 
566 /* Rewrite the port number in an addrinfo list of addresses */
567 static void
568 set_addrinfo_port(struct addrinfo *addrs, int port)
569 {
570 	struct addrinfo *addr;
571 
572 	for (addr = addrs; addr != NULL; addr = addr->ai_next) {
573 		switch (addr->ai_family) {
574 		case AF_INET:
575 			((struct sockaddr_in *)addr->ai_addr)->
576 			    sin_port = htons(port);
577 			break;
578 		case AF_INET6:
579 			((struct sockaddr_in6 *)addr->ai_addr)->
580 			    sin6_port = htons(port);
581 			break;
582 		}
583 	}
584 }
585 
586 /*
587  * Main program for the ssh client.
588  */
589 int
590 main(int ac, char **av)
591 {
592 	struct ssh *ssh = NULL;
593 	int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
594 	int was_addr, config_test = 0, opt_terminated = 0, want_final_pass = 0;
595 	char *p, *cp, *line, *argv0, buf[PATH_MAX], *logfile;
596 	char cname[NI_MAXHOST];
597 	struct stat st;
598 	struct passwd *pw;
599 	extern int optind, optreset;
600 	extern char *optarg;
601 	struct Forward fwd;
602 	struct addrinfo *addrs = NULL;
603 	struct ssh_digest_ctx *md;
604 	u_char conn_hash[SSH_DIGEST_MAX_LENGTH];
605 	size_t n, len;
606 
607 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
608 	sanitise_stdfd();
609 
610 	__progname = ssh_get_progname(av[0]);
611 
612 #ifndef HAVE_SETPROCTITLE
613 	/* Prepare for later setproctitle emulation */
614 	/* Save argv so it isn't clobbered by setproctitle() emulation */
615 	saved_av = xcalloc(ac + 1, sizeof(*saved_av));
616 	for (i = 0; i < ac; i++)
617 		saved_av[i] = xstrdup(av[i]);
618 	saved_av[i] = NULL;
619 	compat_init_setproctitle(ac, av);
620 	av = saved_av;
621 #endif
622 
623 	seed_rng();
624 
625 	/*
626 	 * Discard other fds that are hanging around. These can cause problem
627 	 * with backgrounded ssh processes started by ControlPersist.
628 	 */
629 	closefrom(STDERR_FILENO + 1);
630 
631 	/* Get user data. */
632 	pw = getpwuid(getuid());
633 	if (!pw) {
634 		logit("No user exists for uid %lu", (u_long)getuid());
635 		exit(255);
636 	}
637 	/* Take a copy of the returned structure. */
638 	pw = pwcopy(pw);
639 
640 	/*
641 	 * Set our umask to something reasonable, as some files are created
642 	 * with the default umask.  This will make them world-readable but
643 	 * writable only by the owner, which is ok for all files for which we
644 	 * don't set the modes explicitly.
645 	 */
646 	umask(022);
647 
648 	msetlocale();
649 
650 	/*
651 	 * Initialize option structure to indicate that no values have been
652 	 * set.
653 	 */
654 	initialize_options(&options);
655 
656 	/*
657 	 * Prepare main ssh transport/connection structures
658 	 */
659 	if ((ssh = ssh_alloc_session_state()) == NULL)
660 		fatal("Couldn't allocate session state");
661 	channel_init_channels(ssh);
662 
663 	/* Parse command-line arguments. */
664 	host = NULL;
665 	use_syslog = 0;
666 	logfile = NULL;
667 	argv0 = av[0];
668 
669  again:
670 	while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
671 	    "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) {
672 		switch (opt) {
673 		case '1':
674 			fatal("SSH protocol v.1 is no longer supported");
675 			break;
676 		case '2':
677 			/* Ignored */
678 			break;
679 		case '4':
680 			options.address_family = AF_INET;
681 			break;
682 		case '6':
683 			options.address_family = AF_INET6;
684 			break;
685 		case 'n':
686 			stdin_null_flag = 1;
687 			break;
688 		case 'f':
689 			fork_after_authentication_flag = 1;
690 			stdin_null_flag = 1;
691 			break;
692 		case 'x':
693 			options.forward_x11 = 0;
694 			break;
695 		case 'X':
696 			options.forward_x11 = 1;
697 			break;
698 		case 'y':
699 			use_syslog = 1;
700 			break;
701 		case 'E':
702 			logfile = optarg;
703 			break;
704 		case 'G':
705 			config_test = 1;
706 			break;
707 		case 'Y':
708 			options.forward_x11 = 1;
709 			options.forward_x11_trusted = 1;
710 			break;
711 		case 'g':
712 			options.fwd_opts.gateway_ports = 1;
713 			break;
714 		case 'O':
715 			if (options.stdio_forward_host != NULL)
716 				fatal("Cannot specify multiplexing "
717 				    "command with -W");
718 			else if (muxclient_command != 0)
719 				fatal("Multiplexing command already specified");
720 			if (strcmp(optarg, "check") == 0)
721 				muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
722 			else if (strcmp(optarg, "forward") == 0)
723 				muxclient_command = SSHMUX_COMMAND_FORWARD;
724 			else if (strcmp(optarg, "exit") == 0)
725 				muxclient_command = SSHMUX_COMMAND_TERMINATE;
726 			else if (strcmp(optarg, "stop") == 0)
727 				muxclient_command = SSHMUX_COMMAND_STOP;
728 			else if (strcmp(optarg, "cancel") == 0)
729 				muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
730 			else if (strcmp(optarg, "proxy") == 0)
731 				muxclient_command = SSHMUX_COMMAND_PROXY;
732 			else
733 				fatal("Invalid multiplex command.");
734 			break;
735 		case 'P':	/* deprecated */
736 			break;
737 		case 'Q':
738 			cp = NULL;
739 			if (strcmp(optarg, "cipher") == 0 ||
740 			    strcasecmp(optarg, "Ciphers") == 0)
741 				cp = cipher_alg_list('\n', 0);
742 			else if (strcmp(optarg, "cipher-auth") == 0)
743 				cp = cipher_alg_list('\n', 1);
744 			else if (strcmp(optarg, "mac") == 0 ||
745 			    strcasecmp(optarg, "MACs") == 0)
746 				cp = mac_alg_list('\n');
747 			else if (strcmp(optarg, "kex") == 0 ||
748 			    strcasecmp(optarg, "KexAlgorithms") == 0)
749 				cp = kex_alg_list('\n');
750 			else if (strcmp(optarg, "key") == 0)
751 				cp = sshkey_alg_list(0, 0, 0, '\n');
752 			else if (strcmp(optarg, "key-cert") == 0)
753 				cp = sshkey_alg_list(1, 0, 0, '\n');
754 			else if (strcmp(optarg, "key-plain") == 0)
755 				cp = sshkey_alg_list(0, 1, 0, '\n');
756 			else if (strcmp(optarg, "key-sig") == 0 ||
757 			    strcasecmp(optarg, "PubkeyAcceptedKeyTypes") == 0 ||
758 			    strcasecmp(optarg, "HostKeyAlgorithms") == 0 ||
759 			    strcasecmp(optarg, "HostbasedKeyTypes") == 0 ||
760 			    strcasecmp(optarg, "HostbasedAcceptedKeyTypes") == 0)
761 				cp = sshkey_alg_list(0, 0, 1, '\n');
762 			else if (strcmp(optarg, "sig") == 0)
763 				cp = sshkey_alg_list(0, 1, 1, '\n');
764 			else if (strcmp(optarg, "protocol-version") == 0)
765 				cp = xstrdup("2");
766 			else if (strcmp(optarg, "compression") == 0) {
767 				cp = xstrdup(compression_alg_list(0));
768 				len = strlen(cp);
769 				for (n = 0; n < len; n++)
770 					if (cp[n] == ',')
771 						cp[n] = '\n';
772 			} else if (strcmp(optarg, "help") == 0) {
773 				cp = xstrdup(
774 				    "cipher\ncipher-auth\ncompression\nkex\n"
775 				    "key\nkey-cert\nkey-plain\nkey-sig\nmac\n"
776 				    "protocol-version\nsig");
777 			}
778 			if (cp == NULL)
779 				fatal("Unsupported query \"%s\"", optarg);
780 			printf("%s\n", cp);
781 			free(cp);
782 			exit(0);
783 			break;
784 		case 'a':
785 			options.forward_agent = 0;
786 			break;
787 		case 'A':
788 			options.forward_agent = 1;
789 			break;
790 		case 'k':
791 			options.gss_deleg_creds = 0;
792 			break;
793 		case 'K':
794 			options.gss_authentication = 1;
795 			options.gss_deleg_creds = 1;
796 			break;
797 		case 'i':
798 			p = tilde_expand_filename(optarg, getuid());
799 			if (stat(p, &st) == -1)
800 				fprintf(stderr, "Warning: Identity file %s "
801 				    "not accessible: %s.\n", p,
802 				    strerror(errno));
803 			else
804 				add_identity_file(&options, NULL, p, 1);
805 			free(p);
806 			break;
807 		case 'I':
808 #ifdef ENABLE_PKCS11
809 			free(options.pkcs11_provider);
810 			options.pkcs11_provider = xstrdup(optarg);
811 #else
812 			fprintf(stderr, "no support for PKCS#11.\n");
813 #endif
814 			break;
815 		case 'J':
816 			if (options.jump_host != NULL) {
817 				fatal("Only a single -J option is permitted "
818 				    "(use commas to separate multiple "
819 				    "jump hops)");
820 			}
821 			if (options.proxy_command != NULL)
822 				fatal("Cannot specify -J with ProxyCommand");
823 			if (parse_jump(optarg, &options, 1) == -1)
824 				fatal("Invalid -J argument");
825 			options.proxy_command = xstrdup("none");
826 			break;
827 		case 't':
828 			if (options.request_tty == REQUEST_TTY_YES)
829 				options.request_tty = REQUEST_TTY_FORCE;
830 			else
831 				options.request_tty = REQUEST_TTY_YES;
832 			break;
833 		case 'v':
834 			if (debug_flag == 0) {
835 				debug_flag = 1;
836 				options.log_level = SYSLOG_LEVEL_DEBUG1;
837 			} else {
838 				if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
839 					debug_flag++;
840 					options.log_level++;
841 				}
842 			}
843 			break;
844 		case 'V':
845 			fprintf(stderr, "%s, %s\n",
846 			    SSH_RELEASE,
847 #ifdef WITH_OPENSSL
848 			    OpenSSL_version(OPENSSL_VERSION)
849 #else
850 			    "without OpenSSL"
851 #endif
852 			);
853 			if (opt == 'V')
854 				exit(0);
855 			break;
856 		case 'w':
857 			if (options.tun_open == -1)
858 				options.tun_open = SSH_TUNMODE_DEFAULT;
859 			options.tun_local = a2tun(optarg, &options.tun_remote);
860 			if (options.tun_local == SSH_TUNID_ERR) {
861 				fprintf(stderr,
862 				    "Bad tun device '%s'\n", optarg);
863 				exit(255);
864 			}
865 			break;
866 		case 'W':
867 			if (options.stdio_forward_host != NULL)
868 				fatal("stdio forward already specified");
869 			if (muxclient_command != 0)
870 				fatal("Cannot specify stdio forward with -O");
871 			if (parse_forward(&fwd, optarg, 1, 0)) {
872 				options.stdio_forward_host = fwd.listen_host;
873 				options.stdio_forward_port = fwd.listen_port;
874 				free(fwd.connect_host);
875 			} else {
876 				fprintf(stderr,
877 				    "Bad stdio forwarding specification '%s'\n",
878 				    optarg);
879 				exit(255);
880 			}
881 			options.request_tty = REQUEST_TTY_NO;
882 			no_shell_flag = 1;
883 			break;
884 		case 'q':
885 			options.log_level = SYSLOG_LEVEL_QUIET;
886 			break;
887 		case 'e':
888 			if (optarg[0] == '^' && optarg[2] == 0 &&
889 			    (u_char) optarg[1] >= 64 &&
890 			    (u_char) optarg[1] < 128)
891 				options.escape_char = (u_char) optarg[1] & 31;
892 			else if (strlen(optarg) == 1)
893 				options.escape_char = (u_char) optarg[0];
894 			else if (strcmp(optarg, "none") == 0)
895 				options.escape_char = SSH_ESCAPECHAR_NONE;
896 			else {
897 				fprintf(stderr, "Bad escape character '%s'.\n",
898 				    optarg);
899 				exit(255);
900 			}
901 			break;
902 		case 'c':
903 			if (!ciphers_valid(*optarg == '+' || *optarg == '^' ?
904 			    optarg + 1 : optarg)) {
905 				fprintf(stderr, "Unknown cipher type '%s'\n",
906 				    optarg);
907 				exit(255);
908 			}
909 			free(options.ciphers);
910 			options.ciphers = xstrdup(optarg);
911 			break;
912 		case 'm':
913 			if (mac_valid(optarg)) {
914 				free(options.macs);
915 				options.macs = xstrdup(optarg);
916 			} else {
917 				fprintf(stderr, "Unknown mac type '%s'\n",
918 				    optarg);
919 				exit(255);
920 			}
921 			break;
922 		case 'M':
923 			if (options.control_master == SSHCTL_MASTER_YES)
924 				options.control_master = SSHCTL_MASTER_ASK;
925 			else
926 				options.control_master = SSHCTL_MASTER_YES;
927 			break;
928 		case 'p':
929 			if (options.port == -1) {
930 				options.port = a2port(optarg);
931 				if (options.port <= 0) {
932 					fprintf(stderr, "Bad port '%s'\n",
933 					    optarg);
934 					exit(255);
935 				}
936 			}
937 			break;
938 		case 'l':
939 			if (options.user == NULL)
940 				options.user = optarg;
941 			break;
942 
943 		case 'L':
944 			if (parse_forward(&fwd, optarg, 0, 0))
945 				add_local_forward(&options, &fwd);
946 			else {
947 				fprintf(stderr,
948 				    "Bad local forwarding specification '%s'\n",
949 				    optarg);
950 				exit(255);
951 			}
952 			break;
953 
954 		case 'R':
955 			if (parse_forward(&fwd, optarg, 0, 1) ||
956 			    parse_forward(&fwd, optarg, 1, 1)) {
957 				add_remote_forward(&options, &fwd);
958 			} else {
959 				fprintf(stderr,
960 				    "Bad remote forwarding specification "
961 				    "'%s'\n", optarg);
962 				exit(255);
963 			}
964 			break;
965 
966 		case 'D':
967 			if (parse_forward(&fwd, optarg, 1, 0)) {
968 				add_local_forward(&options, &fwd);
969 			} else {
970 				fprintf(stderr,
971 				    "Bad dynamic forwarding specification "
972 				    "'%s'\n", optarg);
973 				exit(255);
974 			}
975 			break;
976 
977 		case 'C':
978 #ifdef WITH_ZLIB
979 			options.compression = 1;
980 #else
981 			error("Compression not supported, disabling.");
982 #endif
983 			break;
984 		case 'N':
985 			no_shell_flag = 1;
986 			options.request_tty = REQUEST_TTY_NO;
987 			break;
988 		case 'T':
989 			options.request_tty = REQUEST_TTY_NO;
990 			break;
991 		case 'o':
992 			line = xstrdup(optarg);
993 			if (process_config_line(&options, pw,
994 			    host ? host : "", host ? host : "", line,
995 			    "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
996 				exit(255);
997 			free(line);
998 			break;
999 		case 's':
1000 			subsystem_flag = 1;
1001 			break;
1002 		case 'S':
1003 			free(options.control_path);
1004 			options.control_path = xstrdup(optarg);
1005 			break;
1006 		case 'b':
1007 			options.bind_address = optarg;
1008 			break;
1009 		case 'B':
1010 			options.bind_interface = optarg;
1011 			break;
1012 		case 'F':
1013 			config = optarg;
1014 			break;
1015 		default:
1016 			usage();
1017 		}
1018 	}
1019 
1020 	if (optind > 1 && strcmp(av[optind - 1], "--") == 0)
1021 		opt_terminated = 1;
1022 
1023 	ac -= optind;
1024 	av += optind;
1025 
1026 	if (ac > 0 && !host) {
1027 		int tport;
1028 		char *tuser;
1029 		switch (parse_ssh_uri(*av, &tuser, &host, &tport)) {
1030 		case -1:
1031 			usage();
1032 			break;
1033 		case 0:
1034 			if (options.user == NULL) {
1035 				options.user = tuser;
1036 				tuser = NULL;
1037 			}
1038 			free(tuser);
1039 			if (options.port == -1 && tport != -1)
1040 				options.port = tport;
1041 			break;
1042 		default:
1043 			p = xstrdup(*av);
1044 			cp = strrchr(p, '@');
1045 			if (cp != NULL) {
1046 				if (cp == p)
1047 					usage();
1048 				if (options.user == NULL) {
1049 					options.user = p;
1050 					p = NULL;
1051 				}
1052 				*cp++ = '\0';
1053 				host = xstrdup(cp);
1054 				free(p);
1055 			} else
1056 				host = p;
1057 			break;
1058 		}
1059 		if (ac > 1 && !opt_terminated) {
1060 			optind = optreset = 1;
1061 			goto again;
1062 		}
1063 		ac--, av++;
1064 	}
1065 
1066 	/* Check that we got a host name. */
1067 	if (!host)
1068 		usage();
1069 
1070 	host_arg = xstrdup(host);
1071 
1072 	/* Initialize the command to execute on remote host. */
1073 	if ((command = sshbuf_new()) == NULL)
1074 		fatal("sshbuf_new failed");
1075 
1076 	/*
1077 	 * Save the command to execute on the remote host in a buffer. There
1078 	 * is no limit on the length of the command, except by the maximum
1079 	 * packet size.  Also sets the tty flag if there is no command.
1080 	 */
1081 	if (!ac) {
1082 		/* No command specified - execute shell on a tty. */
1083 		if (subsystem_flag) {
1084 			fprintf(stderr,
1085 			    "You must specify a subsystem to invoke.\n");
1086 			usage();
1087 		}
1088 	} else {
1089 		/* A command has been specified.  Store it into the buffer. */
1090 		for (i = 0; i < ac; i++) {
1091 			if ((r = sshbuf_putf(command, "%s%s",
1092 			    i ? " " : "", av[i])) != 0)
1093 				fatal("%s: buffer error: %s",
1094 				    __func__, ssh_err(r));
1095 		}
1096 	}
1097 
1098 	/*
1099 	 * Initialize "log" output.  Since we are the client all output
1100 	 * goes to stderr unless otherwise specified by -y or -E.
1101 	 */
1102 	if (use_syslog && logfile != NULL)
1103 		fatal("Can't specify both -y and -E");
1104 	if (logfile != NULL)
1105 		log_redirect_stderr_to(logfile);
1106 	log_init(argv0,
1107 	    options.log_level == SYSLOG_LEVEL_NOT_SET ?
1108 	    SYSLOG_LEVEL_INFO : options.log_level,
1109 	    options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1110 	    SYSLOG_FACILITY_USER : options.log_facility,
1111 	    !use_syslog);
1112 
1113 	if (debug_flag)
1114 		logit("%s, %s", SSH_RELEASE,
1115 #ifdef WITH_OPENSSL
1116 		    OpenSSL_version(OPENSSL_VERSION)
1117 #else
1118 		    "without OpenSSL"
1119 #endif
1120 		);
1121 
1122 	/* Parse the configuration files */
1123 	process_config_files(host_arg, pw, 0, &want_final_pass);
1124 	if (want_final_pass)
1125 		debug("configuration requests final Match pass");
1126 
1127 	/* Hostname canonicalisation needs a few options filled. */
1128 	fill_default_options_for_canonicalization(&options);
1129 
1130 	/* If the user has replaced the hostname then take it into use now */
1131 	if (options.hostname != NULL) {
1132 		/* NB. Please keep in sync with readconf.c:match_cfg_line() */
1133 		cp = percent_expand(options.hostname,
1134 		    "h", host, (char *)NULL);
1135 		free(host);
1136 		host = cp;
1137 		free(options.hostname);
1138 		options.hostname = xstrdup(host);
1139 	}
1140 
1141 	/* Don't lowercase addresses, they will be explicitly canonicalised */
1142 	if ((was_addr = is_addr(host)) == 0)
1143 		lowercase(host);
1144 
1145 	/*
1146 	 * Try to canonicalize if requested by configuration or the
1147 	 * hostname is an address.
1148 	 */
1149 	if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
1150 		addrs = resolve_canonicalize(&host, options.port);
1151 
1152 	/*
1153 	 * If CanonicalizePermittedCNAMEs have been specified but
1154 	 * other canonicalization did not happen (by not being requested
1155 	 * or by failing with fallback) then the hostname may still be changed
1156 	 * as a result of CNAME following.
1157 	 *
1158 	 * Try to resolve the bare hostname name using the system resolver's
1159 	 * usual search rules and then apply the CNAME follow rules.
1160 	 *
1161 	 * Skip the lookup if a ProxyCommand is being used unless the user
1162 	 * has specifically requested canonicalisation for this case via
1163 	 * CanonicalizeHostname=always
1164 	 */
1165 	direct = option_clear_or_none(options.proxy_command) &&
1166 	    options.jump_host == NULL;
1167 	if (addrs == NULL && options.num_permitted_cnames != 0 && (direct ||
1168 	    options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1169 		if ((addrs = resolve_host(host, options.port,
1170 		    direct, cname, sizeof(cname))) == NULL) {
1171 			/* Don't fatal proxied host names not in the DNS */
1172 			if (direct)
1173 				cleanup_exit(255); /* logged in resolve_host */
1174 		} else
1175 			check_follow_cname(direct, &host, cname);
1176 	}
1177 
1178 	/*
1179 	 * If canonicalisation is enabled then re-parse the configuration
1180 	 * files as new stanzas may match.
1181 	 */
1182 	if (options.canonicalize_hostname != 0 && !want_final_pass) {
1183 		debug("hostname canonicalisation enabled, "
1184 		    "will re-parse configuration");
1185 		want_final_pass = 1;
1186 	}
1187 
1188 	if (want_final_pass) {
1189 		debug("re-parsing configuration");
1190 		free(options.hostname);
1191 		options.hostname = xstrdup(host);
1192 		process_config_files(host_arg, pw, 1, NULL);
1193 		/*
1194 		 * Address resolution happens early with canonicalisation
1195 		 * enabled and the port number may have changed since, so
1196 		 * reset it in address list
1197 		 */
1198 		if (addrs != NULL && options.port > 0)
1199 			set_addrinfo_port(addrs, options.port);
1200 	}
1201 
1202 	/* Fill configuration defaults. */
1203 	fill_default_options(&options);
1204 
1205 	/*
1206 	 * If ProxyJump option specified, then construct a ProxyCommand now.
1207 	 */
1208 	if (options.jump_host != NULL) {
1209 		char port_s[8];
1210 		const char *sshbin = argv0;
1211 		int port = options.port, jumpport = options.jump_port;
1212 
1213 		if (port <= 0)
1214 			port = default_ssh_port();
1215 		if (jumpport <= 0)
1216 			jumpport = default_ssh_port();
1217 		if (strcmp(options.jump_host, host) == 0 && port == jumpport)
1218 			fatal("jumphost loop via %s", options.jump_host);
1219 
1220 		/*
1221 		 * Try to use SSH indicated by argv[0], but fall back to
1222 		 * "ssh" if it appears unavailable.
1223 		 */
1224 		if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
1225 			sshbin = "ssh";
1226 
1227 		/* Consistency check */
1228 		if (options.proxy_command != NULL)
1229 			fatal("inconsistent options: ProxyCommand+ProxyJump");
1230 		/* Never use FD passing for ProxyJump */
1231 		options.proxy_use_fdpass = 0;
1232 		snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
1233 		xasprintf(&options.proxy_command,
1234 		    "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
1235 		    sshbin,
1236 		    /* Optional "-l user" argument if jump_user set */
1237 		    options.jump_user == NULL ? "" : " -l ",
1238 		    options.jump_user == NULL ? "" : options.jump_user,
1239 		    /* Optional "-p port" argument if jump_port set */
1240 		    options.jump_port <= 0 ? "" : " -p ",
1241 		    options.jump_port <= 0 ? "" : port_s,
1242 		    /* Optional additional jump hosts ",..." */
1243 		    options.jump_extra == NULL ? "" : " -J ",
1244 		    options.jump_extra == NULL ? "" : options.jump_extra,
1245 		    /* Optional "-F" argumment if -F specified */
1246 		    config == NULL ? "" : " -F ",
1247 		    config == NULL ? "" : config,
1248 		    /* Optional "-v" arguments if -v set */
1249 		    debug_flag ? " -" : "",
1250 		    debug_flag, "vvv",
1251 		    /* Mandatory hostname */
1252 		    options.jump_host);
1253 		debug("Setting implicit ProxyCommand from ProxyJump: %s",
1254 		    options.proxy_command);
1255 	}
1256 
1257 	if (options.port == 0)
1258 		options.port = default_ssh_port();
1259 	channel_set_af(ssh, options.address_family);
1260 
1261 	/* Tidy and check options */
1262 	if (options.host_key_alias != NULL)
1263 		lowercase(options.host_key_alias);
1264 	if (options.proxy_command != NULL &&
1265 	    strcmp(options.proxy_command, "-") == 0 &&
1266 	    options.proxy_use_fdpass)
1267 		fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1268 	if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1269 		if (options.control_persist && options.control_path != NULL) {
1270 			debug("UpdateHostKeys=ask is incompatible with "
1271 			    "ControlPersist; disabling");
1272 			options.update_hostkeys = 0;
1273 		} else if (sshbuf_len(command) != 0 ||
1274 		    options.remote_command != NULL ||
1275 		    options.request_tty == REQUEST_TTY_NO) {
1276 			debug("UpdateHostKeys=ask is incompatible with "
1277 			    "remote command execution; disabling");
1278 			options.update_hostkeys = 0;
1279 		} else if (options.log_level < SYSLOG_LEVEL_INFO) {
1280 			/* no point logging anything; user won't see it */
1281 			options.update_hostkeys = 0;
1282 		}
1283 	}
1284 	if (options.connection_attempts <= 0)
1285 		fatal("Invalid number of ConnectionAttempts");
1286 
1287 	if (sshbuf_len(command) != 0 && options.remote_command != NULL)
1288 		fatal("Cannot execute command-line and remote command.");
1289 
1290 	/* Cannot fork to background if no command. */
1291 	if (fork_after_authentication_flag && sshbuf_len(command) == 0 &&
1292 	    options.remote_command == NULL && !no_shell_flag)
1293 		fatal("Cannot fork into background without a command "
1294 		    "to execute.");
1295 
1296 	/* reinit */
1297 	log_init(argv0, options.log_level, options.log_facility, !use_syslog);
1298 
1299 	if (options.request_tty == REQUEST_TTY_YES ||
1300 	    options.request_tty == REQUEST_TTY_FORCE)
1301 		tty_flag = 1;
1302 
1303 	/* Allocate a tty by default if no command specified. */
1304 	if (sshbuf_len(command) == 0 && options.remote_command == NULL)
1305 		tty_flag = options.request_tty != REQUEST_TTY_NO;
1306 
1307 	/* Force no tty */
1308 	if (options.request_tty == REQUEST_TTY_NO ||
1309 	    (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY))
1310 		tty_flag = 0;
1311 	/* Do not allocate a tty if stdin is not a tty. */
1312 	if ((!isatty(fileno(stdin)) || stdin_null_flag) &&
1313 	    options.request_tty != REQUEST_TTY_FORCE) {
1314 		if (tty_flag)
1315 			logit("Pseudo-terminal will not be allocated because "
1316 			    "stdin is not a terminal.");
1317 		tty_flag = 0;
1318 	}
1319 
1320 	if (options.user == NULL)
1321 		options.user = xstrdup(pw->pw_name);
1322 
1323 	/* Set up strings used to percent_expand() arguments */
1324 	if (gethostname(thishost, sizeof(thishost)) == -1)
1325 		fatal("gethostname: %s", strerror(errno));
1326 	strlcpy(shorthost, thishost, sizeof(shorthost));
1327 	shorthost[strcspn(thishost, ".")] = '\0';
1328 	snprintf(portstr, sizeof(portstr), "%d", options.port);
1329 	snprintf(uidstr, sizeof(uidstr), "%llu",
1330 	    (unsigned long long)pw->pw_uid);
1331 
1332 	if ((md = ssh_digest_start(SSH_DIGEST_SHA1)) == NULL ||
1333 	    ssh_digest_update(md, thishost, strlen(thishost)) < 0 ||
1334 	    ssh_digest_update(md, host, strlen(host)) < 0 ||
1335 	    ssh_digest_update(md, portstr, strlen(portstr)) < 0 ||
1336 	    ssh_digest_update(md, options.user, strlen(options.user)) < 0 ||
1337 	    ssh_digest_final(md, conn_hash, sizeof(conn_hash)) < 0)
1338 		fatal("%s: mux digest failed", __func__);
1339 	ssh_digest_free(md);
1340 	conn_hash_hex = tohex(conn_hash, ssh_digest_bytes(SSH_DIGEST_SHA1));
1341 
1342 	/*
1343 	 * Expand tokens in arguments. NB. LocalCommand is expanded later,
1344 	 * after port-forwarding is set up, so it may pick up any local
1345 	 * tunnel interface name allocated.
1346 	 */
1347 	if (options.remote_command != NULL) {
1348 		debug3("expanding RemoteCommand: %s", options.remote_command);
1349 		cp = options.remote_command;
1350 		options.remote_command = percent_expand(cp,
1351 		    "C", conn_hash_hex,
1352 		    "L", shorthost,
1353 		    "d", pw->pw_dir,
1354 		    "h", host,
1355 		    "i", uidstr,
1356 		    "l", thishost,
1357 		    "n", host_arg,
1358 		    "p", portstr,
1359 		    "r", options.user,
1360 		    "u", pw->pw_name,
1361 		    (char *)NULL);
1362 		debug3("expanded RemoteCommand: %s", options.remote_command);
1363 		free(cp);
1364 		if ((r = sshbuf_put(command, options.remote_command,
1365 		    strlen(options.remote_command))) != 0)
1366 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
1367 	}
1368 
1369 	if (options.control_path != NULL) {
1370 		cp = tilde_expand_filename(options.control_path, getuid());
1371 		free(options.control_path);
1372 		options.control_path = percent_expand(cp,
1373 		    "C", conn_hash_hex,
1374 		    "L", shorthost,
1375 		    "h", host,
1376 		    "i", uidstr,
1377 		    "l", thishost,
1378 		    "n", host_arg,
1379 		    "p", portstr,
1380 		    "r", options.user,
1381 		    "u", pw->pw_name,
1382 		    "i", uidstr,
1383 		    (char *)NULL);
1384 		free(cp);
1385 	}
1386 
1387 	if (config_test) {
1388 		dump_client_config(&options, host);
1389 		exit(0);
1390 	}
1391 
1392 	/* Expand SecurityKeyProvider if it refers to an environment variable */
1393 	if (options.sk_provider != NULL && *options.sk_provider == '$' &&
1394 	    strlen(options.sk_provider) > 1) {
1395 		if ((cp = getenv(options.sk_provider + 1)) == NULL) {
1396 			debug("Authenticator provider %s did not resolve; "
1397 			    "disabling", options.sk_provider);
1398 			free(options.sk_provider);
1399 			options.sk_provider = NULL;
1400 		} else {
1401 			debug2("resolved SecurityKeyProvider %s => %s",
1402 			    options.sk_provider, cp);
1403 			free(options.sk_provider);
1404 			options.sk_provider = xstrdup(cp);
1405 		}
1406 	}
1407 
1408 	if (muxclient_command != 0 && options.control_path == NULL)
1409 		fatal("No ControlPath specified for \"-O\" command");
1410 	if (options.control_path != NULL) {
1411 		int sock;
1412 		if ((sock = muxclient(options.control_path)) >= 0) {
1413 			ssh_packet_set_connection(ssh, sock, sock);
1414 			ssh_packet_set_mux(ssh);
1415 			goto skip_connect;
1416 		}
1417 	}
1418 
1419 	/*
1420 	 * If hostname canonicalisation was not enabled, then we may not
1421 	 * have yet resolved the hostname. Do so now.
1422 	 */
1423 	if (addrs == NULL && options.proxy_command == NULL) {
1424 		debug2("resolving \"%s\" port %d", host, options.port);
1425 		if ((addrs = resolve_host(host, options.port, 1,
1426 		    cname, sizeof(cname))) == NULL)
1427 			cleanup_exit(255); /* resolve_host logs the error */
1428 	}
1429 
1430 	timeout_ms = options.connection_timeout * 1000;
1431 
1432 	/* Open a connection to the remote host. */
1433 	if (ssh_connect(ssh, host, host_arg, addrs, &hostaddr, options.port,
1434 	    options.address_family, options.connection_attempts,
1435 	    &timeout_ms, options.tcp_keep_alive) != 0)
1436  		exit(255);
1437 
1438 	if (addrs != NULL)
1439 		freeaddrinfo(addrs);
1440 
1441 	ssh_packet_set_timeout(ssh, options.server_alive_interval,
1442 	    options.server_alive_count_max);
1443 
1444 	if (timeout_ms > 0)
1445 		debug3("timeout: %d ms remain after connect", timeout_ms);
1446 
1447 	/*
1448 	 * If we successfully made the connection and we have hostbased auth
1449 	 * enabled, load the public keys so we can later use the ssh-keysign
1450 	 * helper to sign challenges.
1451 	 */
1452 	sensitive_data.nkeys = 0;
1453 	sensitive_data.keys = NULL;
1454 	if (options.hostbased_authentication) {
1455 		sensitive_data.nkeys = 10;
1456 		sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1457 		    sizeof(struct sshkey));
1458 
1459 		/* XXX check errors? */
1460 #define L_PUBKEY(p,o) do { \
1461 	if ((o) >= sensitive_data.nkeys) \
1462 		fatal("%s pubkey out of array bounds", __func__); \
1463 	check_load(sshkey_load_public(p, &(sensitive_data.keys[o]), NULL), \
1464 	    p, "pubkey"); \
1465 } while (0)
1466 #define L_CERT(p,o) do { \
1467 	if ((o) >= sensitive_data.nkeys) \
1468 		fatal("%s cert out of array bounds", __func__); \
1469 	check_load(sshkey_load_cert(p, &(sensitive_data.keys[o])), p, "cert"); \
1470 } while (0)
1471 
1472 		if (options.hostbased_authentication == 1) {
1473 			L_CERT(_PATH_HOST_ECDSA_KEY_FILE, 0);
1474 			L_CERT(_PATH_HOST_ED25519_KEY_FILE, 1);
1475 			L_CERT(_PATH_HOST_RSA_KEY_FILE, 2);
1476 			L_CERT(_PATH_HOST_DSA_KEY_FILE, 3);
1477 			L_PUBKEY(_PATH_HOST_ECDSA_KEY_FILE, 4);
1478 			L_PUBKEY(_PATH_HOST_ED25519_KEY_FILE, 5);
1479 			L_PUBKEY(_PATH_HOST_RSA_KEY_FILE, 6);
1480 			L_PUBKEY(_PATH_HOST_DSA_KEY_FILE, 7);
1481 			L_CERT(_PATH_HOST_XMSS_KEY_FILE, 8);
1482 			L_PUBKEY(_PATH_HOST_XMSS_KEY_FILE, 9);
1483 		}
1484 	}
1485 
1486 	/* Create ~/.ssh * directory if it doesn't already exist. */
1487 	if (config == NULL) {
1488 		r = snprintf(buf, sizeof buf, "%s%s%s", pw->pw_dir,
1489 		    strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
1490 		if (r > 0 && (size_t)r < sizeof(buf) && stat(buf, &st) == -1) {
1491 #ifdef WITH_SELINUX
1492 			ssh_selinux_setfscreatecon(buf);
1493 #endif
1494 			if (mkdir(buf, 0700) < 0)
1495 				error("Could not create directory '%.200s'.",
1496 				    buf);
1497 #ifdef WITH_SELINUX
1498 			ssh_selinux_setfscreatecon(NULL);
1499 #endif
1500 		}
1501 	}
1502 	/* load options.identity_files */
1503 	load_public_identity_files(pw);
1504 
1505 	/* optionally set the SSH_AUTHSOCKET_ENV_NAME variable */
1506 	if (options.identity_agent &&
1507 	    strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
1508 		if (strcmp(options.identity_agent, "none") == 0) {
1509 			unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1510 		} else {
1511 			p = tilde_expand_filename(options.identity_agent,
1512 			    getuid());
1513 			cp = percent_expand(p,
1514 			    "d", pw->pw_dir,
1515 			    "h", host,
1516 			    "i", uidstr,
1517 			    "l", thishost,
1518 			    "r", options.user,
1519 			    "u", pw->pw_name,
1520 			    (char *)NULL);
1521 			free(p);
1522 			/*
1523 			 * If identity_agent represents an environment variable
1524 			 * then recheck that it is valid (since processing with
1525 			 * percent_expand() may have changed it) and substitute
1526 			 * its value.
1527 			 */
1528 			if (cp[0] == '$') {
1529 				if (!valid_env_name(cp + 1)) {
1530 					fatal("Invalid IdentityAgent "
1531 					    "environment variable name %s", cp);
1532 				}
1533 				if ((p = getenv(cp + 1)) == NULL)
1534 					unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1535 				else
1536 					setenv(SSH_AUTHSOCKET_ENV_NAME, p, 1);
1537 			} else {
1538 				/* identity_agent specifies a path directly */
1539 				setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
1540 			}
1541 			free(cp);
1542 		}
1543 	}
1544 
1545 	if (options.forward_agent && (options.forward_agent_sock_path != NULL)) {
1546 		p = tilde_expand_filename(options.forward_agent_sock_path, getuid());
1547 		cp = percent_expand(p,
1548 		    "d", pw->pw_dir,
1549 		    "h", host,
1550 		    "i", uidstr,
1551 		    "l", thishost,
1552 		    "r", options.user,
1553 		    "u", pw->pw_name,
1554 		    (char *)NULL);
1555 		free(p);
1556 
1557 		if (cp[0] == '$') {
1558 			if (!valid_env_name(cp + 1)) {
1559 				fatal("Invalid ForwardAgent environment variable name %s", cp);
1560 			}
1561 			if ((p = getenv(cp + 1)) != NULL)
1562 				forward_agent_sock_path = p;
1563 			else
1564 				options.forward_agent = 0;
1565 			free(cp);
1566 		} else {
1567 			forward_agent_sock_path = cp;
1568 		}
1569 	}
1570 
1571 	/* Expand ~ in known host file names. */
1572 	tilde_expand_paths(options.system_hostfiles,
1573 	    options.num_system_hostfiles);
1574 	tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1575 
1576 	ssh_signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1577 	ssh_signal(SIGCHLD, main_sigchld_handler);
1578 
1579 	/* Log into the remote system.  Never returns if the login fails. */
1580 	ssh_login(ssh, &sensitive_data, host, (struct sockaddr *)&hostaddr,
1581 	    options.port, pw, timeout_ms);
1582 
1583 	if (ssh_packet_connection_is_on_socket(ssh)) {
1584 		verbose("Authenticated to %s ([%s]:%d).", host,
1585 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
1586 	} else {
1587 		verbose("Authenticated to %s (via proxy).", host);
1588 	}
1589 
1590 	/* We no longer need the private host keys.  Clear them now. */
1591 	if (sensitive_data.nkeys != 0) {
1592 		for (i = 0; i < sensitive_data.nkeys; i++) {
1593 			if (sensitive_data.keys[i] != NULL) {
1594 				/* Destroys contents safely */
1595 				debug3("clear hostkey %d", i);
1596 				sshkey_free(sensitive_data.keys[i]);
1597 				sensitive_data.keys[i] = NULL;
1598 			}
1599 		}
1600 		free(sensitive_data.keys);
1601 	}
1602 	for (i = 0; i < options.num_identity_files; i++) {
1603 		free(options.identity_files[i]);
1604 		options.identity_files[i] = NULL;
1605 		if (options.identity_keys[i]) {
1606 			sshkey_free(options.identity_keys[i]);
1607 			options.identity_keys[i] = NULL;
1608 		}
1609 	}
1610 	for (i = 0; i < options.num_certificate_files; i++) {
1611 		free(options.certificate_files[i]);
1612 		options.certificate_files[i] = NULL;
1613 	}
1614 
1615  skip_connect:
1616 	exit_status = ssh_session2(ssh, pw);
1617 	ssh_packet_close(ssh);
1618 
1619 	if (options.control_path != NULL && muxserver_sock != -1)
1620 		unlink(options.control_path);
1621 
1622 	/* Kill ProxyCommand if it is running. */
1623 	ssh_kill_proxy_command();
1624 
1625 	return exit_status;
1626 }
1627 
1628 static void
1629 control_persist_detach(void)
1630 {
1631 	pid_t pid;
1632 	int devnull, keep_stderr;
1633 
1634 	debug("%s: backgrounding master process", __func__);
1635 
1636 	/*
1637 	 * master (current process) into the background, and make the
1638 	 * foreground process a client of the backgrounded master.
1639 	 */
1640 	switch ((pid = fork())) {
1641 	case -1:
1642 		fatal("%s: fork: %s", __func__, strerror(errno));
1643 	case 0:
1644 		/* Child: master process continues mainloop */
1645 		break;
1646 	default:
1647 		/* Parent: set up mux slave to connect to backgrounded master */
1648 		debug2("%s: background process is %ld", __func__, (long)pid);
1649 		stdin_null_flag = ostdin_null_flag;
1650 		options.request_tty = orequest_tty;
1651 		tty_flag = otty_flag;
1652 		close(muxserver_sock);
1653 		muxserver_sock = -1;
1654 		options.control_master = SSHCTL_MASTER_NO;
1655 		muxclient(options.control_path);
1656 		/* muxclient() doesn't return on success. */
1657 		fatal("Failed to connect to new control master");
1658 	}
1659 	if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
1660 		error("%s: open(\"/dev/null\"): %s", __func__,
1661 		    strerror(errno));
1662 	} else {
1663 		keep_stderr = log_is_on_stderr() && debug_flag;
1664 		if (dup2(devnull, STDIN_FILENO) == -1 ||
1665 		    dup2(devnull, STDOUT_FILENO) == -1 ||
1666 		    (!keep_stderr && dup2(devnull, STDERR_FILENO) == -1))
1667 			error("%s: dup2: %s", __func__, strerror(errno));
1668 		if (devnull > STDERR_FILENO)
1669 			close(devnull);
1670 	}
1671 	daemon(1, 1);
1672 	setproctitle("%s [mux]", options.control_path);
1673 }
1674 
1675 /* Do fork() after authentication. Used by "ssh -f" */
1676 static void
1677 fork_postauth(void)
1678 {
1679 	if (need_controlpersist_detach)
1680 		control_persist_detach();
1681 	debug("forking to background");
1682 	fork_after_authentication_flag = 0;
1683 	if (daemon(1, 1) == -1)
1684 		fatal("daemon() failed: %.200s", strerror(errno));
1685 }
1686 
1687 /* Callback for remote forward global requests */
1688 static void
1689 ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
1690 {
1691 	struct Forward *rfwd = (struct Forward *)ctxt;
1692 	u_int port;
1693 	int r;
1694 
1695 	/* XXX verbose() on failure? */
1696 	debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1697 	    type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1698 	    rfwd->listen_path ? rfwd->listen_path :
1699 	    rfwd->listen_host ? rfwd->listen_host : "",
1700 	    (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1701 	    rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1702 	    rfwd->connect_host, rfwd->connect_port);
1703 	if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1704 		if (type == SSH2_MSG_REQUEST_SUCCESS) {
1705 			if ((r = sshpkt_get_u32(ssh, &port)) != 0)
1706 				fatal("%s: %s", __func__, ssh_err(r));
1707 			if (port > 65535) {
1708 				error("Invalid allocated port %u for remote "
1709 				    "forward to %s:%d", port,
1710 				    rfwd->connect_host, rfwd->connect_port);
1711 				/* Ensure failure processing runs below */
1712 				type = SSH2_MSG_REQUEST_FAILURE;
1713 				channel_update_permission(ssh,
1714 				    rfwd->handle, -1);
1715 			} else {
1716 				rfwd->allocated_port = (int)port;
1717 				logit("Allocated port %u for remote "
1718 				    "forward to %s:%d",
1719 				    rfwd->allocated_port, rfwd->connect_host,
1720 				    rfwd->connect_port);
1721 				channel_update_permission(ssh,
1722 				    rfwd->handle, rfwd->allocated_port);
1723 			}
1724 		} else {
1725 			channel_update_permission(ssh, rfwd->handle, -1);
1726 		}
1727 	}
1728 
1729 	if (type == SSH2_MSG_REQUEST_FAILURE) {
1730 		if (options.exit_on_forward_failure) {
1731 			if (rfwd->listen_path != NULL)
1732 				fatal("Error: remote port forwarding failed "
1733 				    "for listen path %s", rfwd->listen_path);
1734 			else
1735 				fatal("Error: remote port forwarding failed "
1736 				    "for listen port %d", rfwd->listen_port);
1737 		} else {
1738 			if (rfwd->listen_path != NULL)
1739 				logit("Warning: remote port forwarding failed "
1740 				    "for listen path %s", rfwd->listen_path);
1741 			else
1742 				logit("Warning: remote port forwarding failed "
1743 				    "for listen port %d", rfwd->listen_port);
1744 		}
1745 	}
1746 	if (++remote_forward_confirms_received == options.num_remote_forwards) {
1747 		debug("All remote forwarding requests processed");
1748 		if (fork_after_authentication_flag)
1749 			fork_postauth();
1750 	}
1751 }
1752 
1753 static void
1754 client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
1755 {
1756 	debug("stdio forwarding: done");
1757 	cleanup_exit(0);
1758 }
1759 
1760 static void
1761 ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1762 {
1763 	if (!success)
1764 		fatal("stdio forwarding failed");
1765 }
1766 
1767 static void
1768 ssh_init_stdio_forwarding(struct ssh *ssh)
1769 {
1770 	Channel *c;
1771 	int in, out;
1772 
1773 	if (options.stdio_forward_host == NULL)
1774 		return;
1775 
1776 	debug3("%s: %s:%d", __func__, options.stdio_forward_host,
1777 	    options.stdio_forward_port);
1778 
1779 	if ((in = dup(STDIN_FILENO)) == -1 ||
1780 	    (out = dup(STDOUT_FILENO)) == -1)
1781 		fatal("channel_connect_stdio_fwd: dup() in/out failed");
1782 	if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
1783 	    options.stdio_forward_port, in, out)) == NULL)
1784 		fatal("%s: channel_connect_stdio_fwd failed", __func__);
1785 	channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
1786 	channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
1787 }
1788 
1789 static void
1790 ssh_init_forwarding(struct ssh *ssh, char **ifname)
1791 {
1792 	int success = 0;
1793 	int i;
1794 
1795 	/* Initiate local TCP/IP port forwardings. */
1796 	for (i = 0; i < options.num_local_forwards; i++) {
1797 		debug("Local connections to %.200s:%d forwarded to remote "
1798 		    "address %.200s:%d",
1799 		    (options.local_forwards[i].listen_path != NULL) ?
1800 		    options.local_forwards[i].listen_path :
1801 		    (options.local_forwards[i].listen_host == NULL) ?
1802 		    (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1803 		    options.local_forwards[i].listen_host,
1804 		    options.local_forwards[i].listen_port,
1805 		    (options.local_forwards[i].connect_path != NULL) ?
1806 		    options.local_forwards[i].connect_path :
1807 		    options.local_forwards[i].connect_host,
1808 		    options.local_forwards[i].connect_port);
1809 		success += channel_setup_local_fwd_listener(ssh,
1810 		    &options.local_forwards[i], &options.fwd_opts);
1811 	}
1812 	if (i > 0 && success != i && options.exit_on_forward_failure)
1813 		fatal("Could not request local forwarding.");
1814 	if (i > 0 && success == 0)
1815 		error("Could not request local forwarding.");
1816 
1817 	/* Initiate remote TCP/IP port forwardings. */
1818 	for (i = 0; i < options.num_remote_forwards; i++) {
1819 		debug("Remote connections from %.200s:%d forwarded to "
1820 		    "local address %.200s:%d",
1821 		    (options.remote_forwards[i].listen_path != NULL) ?
1822 		    options.remote_forwards[i].listen_path :
1823 		    (options.remote_forwards[i].listen_host == NULL) ?
1824 		    "LOCALHOST" : options.remote_forwards[i].listen_host,
1825 		    options.remote_forwards[i].listen_port,
1826 		    (options.remote_forwards[i].connect_path != NULL) ?
1827 		    options.remote_forwards[i].connect_path :
1828 		    options.remote_forwards[i].connect_host,
1829 		    options.remote_forwards[i].connect_port);
1830 		options.remote_forwards[i].handle =
1831 		    channel_request_remote_forwarding(ssh,
1832 		    &options.remote_forwards[i]);
1833 		if (options.remote_forwards[i].handle < 0) {
1834 			if (options.exit_on_forward_failure)
1835 				fatal("Could not request remote forwarding.");
1836 			else
1837 				logit("Warning: Could not request remote "
1838 				    "forwarding.");
1839 		} else {
1840 			client_register_global_confirm(
1841 			    ssh_confirm_remote_forward,
1842 			    &options.remote_forwards[i]);
1843 		}
1844 	}
1845 
1846 	/* Initiate tunnel forwarding. */
1847 	if (options.tun_open != SSH_TUNMODE_NO) {
1848 		if ((*ifname = client_request_tun_fwd(ssh,
1849 		    options.tun_open, options.tun_local,
1850 		    options.tun_remote)) == NULL) {
1851 			if (options.exit_on_forward_failure)
1852 				fatal("Could not request tunnel forwarding.");
1853 			else
1854 				error("Could not request tunnel forwarding.");
1855 		}
1856 	}
1857 }
1858 
1859 static void
1860 check_agent_present(void)
1861 {
1862 	int r;
1863 
1864 	if (options.forward_agent) {
1865 		/* Clear agent forwarding if we don't have an agent. */
1866 		if ((r = ssh_get_authentication_socket(NULL)) != 0) {
1867 			options.forward_agent = 0;
1868 			if (r != SSH_ERR_AGENT_NOT_PRESENT)
1869 				debug("ssh_get_authentication_socket: %s",
1870 				    ssh_err(r));
1871 		}
1872 	}
1873 }
1874 
1875 static void
1876 ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
1877 {
1878 	extern char **environ;
1879 	const char *display;
1880 	int r, interactive = tty_flag;
1881 	char *proto = NULL, *data = NULL;
1882 
1883 	if (!success)
1884 		return; /* No need for error message, channels code sens one */
1885 
1886 	display = getenv("DISPLAY");
1887 	if (display == NULL && options.forward_x11)
1888 		debug("X11 forwarding requested but DISPLAY not set");
1889 	if (options.forward_x11 && client_x11_get_proto(ssh, display,
1890 	    options.xauth_location, options.forward_x11_trusted,
1891 	    options.forward_x11_timeout, &proto, &data) == 0) {
1892 		/* Request forwarding with authentication spoofing. */
1893 		debug("Requesting X11 forwarding with authentication "
1894 		    "spoofing.");
1895 		x11_request_forwarding_with_spoofing(ssh, id, display, proto,
1896 		    data, 1);
1897 		client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
1898 		/* XXX exit_on_forward_failure */
1899 		interactive = 1;
1900 	}
1901 
1902 	check_agent_present();
1903 	if (options.forward_agent) {
1904 		debug("Requesting authentication agent forwarding.");
1905 		channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
1906 		if ((r = sshpkt_send(ssh)) != 0)
1907 			fatal("%s: %s", __func__, ssh_err(r));
1908 	}
1909 
1910 	/* Tell the packet module whether this is an interactive session. */
1911 	ssh_packet_set_interactive(ssh, interactive,
1912 	    options.ip_qos_interactive, options.ip_qos_bulk);
1913 
1914 	client_session2_setup(ssh, id, tty_flag, subsystem_flag, getenv("TERM"),
1915 	    NULL, fileno(stdin), command, environ);
1916 }
1917 
1918 /* open new channel for a session */
1919 static int
1920 ssh_session2_open(struct ssh *ssh)
1921 {
1922 	Channel *c;
1923 	int window, packetmax, in, out, err;
1924 
1925 	if (stdin_null_flag) {
1926 		in = open(_PATH_DEVNULL, O_RDONLY);
1927 	} else {
1928 		in = dup(STDIN_FILENO);
1929 	}
1930 	out = dup(STDOUT_FILENO);
1931 	err = dup(STDERR_FILENO);
1932 
1933 	if (in == -1 || out == -1 || err == -1)
1934 		fatal("dup() in/out/err failed");
1935 
1936 	/* enable nonblocking unless tty */
1937 	if (!isatty(in))
1938 		set_nonblock(in);
1939 	if (!isatty(out))
1940 		set_nonblock(out);
1941 	if (!isatty(err))
1942 		set_nonblock(err);
1943 
1944 	window = CHAN_SES_WINDOW_DEFAULT;
1945 	packetmax = CHAN_SES_PACKET_DEFAULT;
1946 	if (tty_flag) {
1947 		window >>= 1;
1948 		packetmax >>= 1;
1949 	}
1950 	c = channel_new(ssh,
1951 	    "session", SSH_CHANNEL_OPENING, in, out, err,
1952 	    window, packetmax, CHAN_EXTENDED_WRITE,
1953 	    "client-session", /*nonblock*/0);
1954 
1955 	debug3("%s: channel_new: %d", __func__, c->self);
1956 
1957 	channel_send_open(ssh, c->self);
1958 	if (!no_shell_flag)
1959 		channel_register_open_confirm(ssh, c->self,
1960 		    ssh_session2_setup, NULL);
1961 
1962 	return c->self;
1963 }
1964 
1965 static int
1966 ssh_session2(struct ssh *ssh, struct passwd *pw)
1967 {
1968 	int r, devnull, id = -1;
1969 	char *cp, *tun_fwd_ifname = NULL;
1970 
1971 	/* XXX should be pre-session */
1972 	if (!options.control_persist)
1973 		ssh_init_stdio_forwarding(ssh);
1974 
1975 	ssh_init_forwarding(ssh, &tun_fwd_ifname);
1976 
1977 	if (options.local_command != NULL) {
1978 		debug3("expanding LocalCommand: %s", options.local_command);
1979 		cp = options.local_command;
1980 		options.local_command = percent_expand(cp,
1981 		    "C", conn_hash_hex,
1982 		    "L", shorthost,
1983 		    "d", pw->pw_dir,
1984 		    "h", host,
1985 		    "i", uidstr,
1986 		    "l", thishost,
1987 		    "n", host_arg,
1988 		    "p", portstr,
1989 		    "r", options.user,
1990 		    "u", pw->pw_name,
1991 		    "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
1992 		    (char *)NULL);
1993 		debug3("expanded LocalCommand: %s", options.local_command);
1994 		free(cp);
1995 	}
1996 
1997 	/* Start listening for multiplex clients */
1998 	if (!ssh_packet_get_mux(ssh))
1999 		muxserver_listen(ssh);
2000 
2001 	/*
2002 	 * If we are in control persist mode and have a working mux listen
2003 	 * socket, then prepare to background ourselves and have a foreground
2004 	 * client attach as a control slave.
2005 	 * NB. we must save copies of the flags that we override for
2006 	 * the backgrounding, since we defer attachment of the slave until
2007 	 * after the connection is fully established (in particular,
2008 	 * async rfwd replies have been received for ExitOnForwardFailure).
2009 	 */
2010 	if (options.control_persist && muxserver_sock != -1) {
2011 		ostdin_null_flag = stdin_null_flag;
2012 		ono_shell_flag = no_shell_flag;
2013 		orequest_tty = options.request_tty;
2014 		otty_flag = tty_flag;
2015 		stdin_null_flag = 1;
2016 		no_shell_flag = 1;
2017 		tty_flag = 0;
2018 		if (!fork_after_authentication_flag)
2019 			need_controlpersist_detach = 1;
2020 		fork_after_authentication_flag = 1;
2021 	}
2022 	/*
2023 	 * ControlPersist mux listen socket setup failed, attempt the
2024 	 * stdio forward setup that we skipped earlier.
2025 	 */
2026 	if (options.control_persist && muxserver_sock == -1)
2027 		ssh_init_stdio_forwarding(ssh);
2028 
2029 	if (!no_shell_flag)
2030 		id = ssh_session2_open(ssh);
2031 	else {
2032 		ssh_packet_set_interactive(ssh,
2033 		    options.control_master == SSHCTL_MASTER_NO,
2034 		    options.ip_qos_interactive, options.ip_qos_bulk);
2035 	}
2036 
2037 	/* If we don't expect to open a new session, then disallow it */
2038 	if (options.control_master == SSHCTL_MASTER_NO &&
2039 	    (datafellows & SSH_NEW_OPENSSH)) {
2040 		debug("Requesting no-more-sessions@openssh.com");
2041 		if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2042 		    (r = sshpkt_put_cstring(ssh,
2043 		    "no-more-sessions@openssh.com")) != 0 ||
2044 		    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
2045 		    (r = sshpkt_send(ssh)) != 0)
2046 			fatal("%s: %s", __func__, ssh_err(r));
2047 	}
2048 
2049 	/* Execute a local command */
2050 	if (options.local_command != NULL &&
2051 	    options.permit_local_command)
2052 		ssh_local_cmd(options.local_command);
2053 
2054 	/*
2055 	 * stdout is now owned by the session channel; clobber it here
2056 	 * so future channel closes are propagated to the local fd.
2057 	 * NB. this can only happen after LocalCommand has completed,
2058 	 * as it may want to write to stdout.
2059 	 */
2060 	if (!need_controlpersist_detach) {
2061 		if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1)
2062 			error("%s: open %s: %s", __func__,
2063 			    _PATH_DEVNULL, strerror(errno));
2064 		if (dup2(devnull, STDOUT_FILENO) == -1)
2065 			fatal("%s: dup2() stdout failed", __func__);
2066 		if (devnull > STDERR_FILENO)
2067 			close(devnull);
2068 	}
2069 
2070 	/*
2071 	 * If requested and we are not interested in replies to remote
2072 	 * forwarding requests, then let ssh continue in the background.
2073 	 */
2074 	if (fork_after_authentication_flag) {
2075 		if (options.exit_on_forward_failure &&
2076 		    options.num_remote_forwards > 0) {
2077 			debug("deferring postauth fork until remote forward "
2078 			    "confirmation received");
2079 		} else
2080 			fork_postauth();
2081 	}
2082 
2083 	return client_loop(ssh, tty_flag, tty_flag ?
2084 	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
2085 }
2086 
2087 /* Loads all IdentityFile and CertificateFile keys */
2088 static void
2089 load_public_identity_files(struct passwd *pw)
2090 {
2091 	char *filename, *cp;
2092 	struct sshkey *public;
2093 	int i;
2094 	u_int n_ids, n_certs;
2095 	char *identity_files[SSH_MAX_IDENTITY_FILES];
2096 	struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
2097 	int identity_file_userprovided[SSH_MAX_IDENTITY_FILES];
2098 	char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
2099 	struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
2100 	int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES];
2101 #ifdef ENABLE_PKCS11
2102 	struct sshkey **keys = NULL;
2103 	char **comments = NULL;
2104 	int nkeys;
2105 #endif /* PKCS11 */
2106 
2107 	n_ids = n_certs = 0;
2108 	memset(identity_files, 0, sizeof(identity_files));
2109 	memset(identity_keys, 0, sizeof(identity_keys));
2110 	memset(identity_file_userprovided, 0,
2111 	    sizeof(identity_file_userprovided));
2112 	memset(certificate_files, 0, sizeof(certificate_files));
2113 	memset(certificates, 0, sizeof(certificates));
2114 	memset(certificate_file_userprovided, 0,
2115 	    sizeof(certificate_file_userprovided));
2116 
2117 #ifdef ENABLE_PKCS11
2118 	if (options.pkcs11_provider != NULL &&
2119 	    options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
2120 	    (pkcs11_init(!options.batch_mode) == 0) &&
2121 	    (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
2122 	    &keys, &comments)) > 0) {
2123 		for (i = 0; i < nkeys; i++) {
2124 			if (n_ids >= SSH_MAX_IDENTITY_FILES) {
2125 				sshkey_free(keys[i]);
2126 				free(comments[i]);
2127 				continue;
2128 			}
2129 			identity_keys[n_ids] = keys[i];
2130 			identity_files[n_ids] = comments[i]; /* transferred */
2131 			n_ids++;
2132 		}
2133 		free(keys);
2134 		free(comments);
2135 	}
2136 #endif /* ENABLE_PKCS11 */
2137 	for (i = 0; i < options.num_identity_files; i++) {
2138 		if (n_ids >= SSH_MAX_IDENTITY_FILES ||
2139 		    strcasecmp(options.identity_files[i], "none") == 0) {
2140 			free(options.identity_files[i]);
2141 			options.identity_files[i] = NULL;
2142 			continue;
2143 		}
2144 		cp = tilde_expand_filename(options.identity_files[i], getuid());
2145 		filename = percent_expand(cp, "d", pw->pw_dir,
2146 		    "u", pw->pw_name, "l", thishost, "h", host,
2147 		    "r", options.user, (char *)NULL);
2148 		free(cp);
2149 		check_load(sshkey_load_public(filename, &public, NULL),
2150 		    filename, "pubkey");
2151 		debug("identity file %s type %d", filename,
2152 		    public ? public->type : -1);
2153 		free(options.identity_files[i]);
2154 		identity_files[n_ids] = filename;
2155 		identity_keys[n_ids] = public;
2156 		identity_file_userprovided[n_ids] =
2157 		    options.identity_file_userprovided[i];
2158 		if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2159 			continue;
2160 
2161 		/*
2162 		 * If no certificates have been explicitly listed then try
2163 		 * to add the default certificate variant too.
2164 		 */
2165 		if (options.num_certificate_files != 0)
2166 			continue;
2167 		xasprintf(&cp, "%s-cert", filename);
2168 		check_load(sshkey_load_public(cp, &public, NULL),
2169 		    filename, "pubkey");
2170 		debug("identity file %s type %d", cp,
2171 		    public ? public->type : -1);
2172 		if (public == NULL) {
2173 			free(cp);
2174 			continue;
2175 		}
2176 		if (!sshkey_is_cert(public)) {
2177 			debug("%s: key %s type %s is not a certificate",
2178 			    __func__, cp, sshkey_type(public));
2179 			sshkey_free(public);
2180 			free(cp);
2181 			continue;
2182 		}
2183 		/* NB. leave filename pointing to private key */
2184 		identity_files[n_ids] = xstrdup(filename);
2185 		identity_keys[n_ids] = public;
2186 		identity_file_userprovided[n_ids] =
2187 		    options.identity_file_userprovided[i];
2188 		n_ids++;
2189 	}
2190 
2191 	if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
2192 		fatal("%s: too many certificates", __func__);
2193 	for (i = 0; i < options.num_certificate_files; i++) {
2194 		cp = tilde_expand_filename(options.certificate_files[i],
2195 		    getuid());
2196 		filename = percent_expand(cp,
2197 		    "d", pw->pw_dir,
2198 		    "h", host,
2199 		    "i", uidstr,
2200 		    "l", thishost,
2201 		    "r", options.user,
2202 		    "u", pw->pw_name,
2203 		    (char *)NULL);
2204 		free(cp);
2205 
2206 		check_load(sshkey_load_public(filename, &public, NULL),
2207 		    filename, "certificate");
2208 		debug("certificate file %s type %d", filename,
2209 		    public ? public->type : -1);
2210 		free(options.certificate_files[i]);
2211 		options.certificate_files[i] = NULL;
2212 		if (public == NULL) {
2213 			free(filename);
2214 			continue;
2215 		}
2216 		if (!sshkey_is_cert(public)) {
2217 			debug("%s: key %s type %s is not a certificate",
2218 			    __func__, filename, sshkey_type(public));
2219 			sshkey_free(public);
2220 			free(filename);
2221 			continue;
2222 		}
2223 		certificate_files[n_certs] = filename;
2224 		certificates[n_certs] = public;
2225 		certificate_file_userprovided[n_certs] =
2226 		    options.certificate_file_userprovided[i];
2227 		++n_certs;
2228 	}
2229 
2230 	options.num_identity_files = n_ids;
2231 	memcpy(options.identity_files, identity_files, sizeof(identity_files));
2232 	memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2233 	memcpy(options.identity_file_userprovided,
2234 	    identity_file_userprovided, sizeof(identity_file_userprovided));
2235 
2236 	options.num_certificate_files = n_certs;
2237 	memcpy(options.certificate_files,
2238 	    certificate_files, sizeof(certificate_files));
2239 	memcpy(options.certificates, certificates, sizeof(certificates));
2240 	memcpy(options.certificate_file_userprovided,
2241 	    certificate_file_userprovided,
2242 	    sizeof(certificate_file_userprovided));
2243 }
2244 
2245 static void
2246 main_sigchld_handler(int sig)
2247 {
2248 	int save_errno = errno;
2249 	pid_t pid;
2250 	int status;
2251 
2252 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2253 	    (pid == -1 && errno == EINTR))
2254 		;
2255 	errno = save_errno;
2256 }
2257