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1 /* $OpenBSD: ssh.c,v 1.576 2022/09/17 10:33:18 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 SSLeay 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 "packet.h"
90 #include "sshbuf.h"
91 #include "channels.h"
92 #include "sshkey.h"
93 #include "authfd.h"
94 #include "authfile.h"
95 #include "pathnames.h"
96 #include "dispatch.h"
97 #include "clientloop.h"
98 #include "log.h"
99 #include "misc.h"
100 #include "readconf.h"
101 #include "sshconnect.h"
102 #include "kex.h"
103 #include "mac.h"
104 #include "sshpty.h"
105 #include "match.h"
106 #include "msg.h"
107 #include "version.h"
108 #include "ssherr.h"
109 #include "myproposal.h"
110 #include "utf8.h"
111
112 #ifdef ENABLE_PKCS11
113 #include "ssh-pkcs11.h"
114 #endif
115
116 extern char *__progname;
117
118 /* Saves a copy of argv for setproctitle emulation */
119 #ifndef HAVE_SETPROCTITLE
120 static char **saved_av;
121 #endif
122
123 /* Flag indicating whether debug mode is on.  May be set on the command line. */
124 int debug_flag = 0;
125
126 /* Flag indicating whether a tty should be requested */
127 int tty_flag = 0;
128
129 /*
130  * Flag indicating that the current process should be backgrounded and
131  * a new mux-client launched in the foreground for ControlPersist.
132  */
133 int need_controlpersist_detach = 0;
134
135 /* Copies of flags for ControlPersist foreground mux-client */
136 int ostdin_null_flag, osession_type, otty_flag, orequest_tty;
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 /*
155  * A config can specify a path to forward, overriding SSH_AUTH_SOCK. If this is
156  * not NULL, forward the socket at this path instead.
157  */
158 char *forward_agent_sock_path = NULL;
159
160 /* socket address the host resolves to */
161 struct sockaddr_storage hostaddr;
162
163 /* Private host keys. */
164 Sensitive sensitive_data;
165
166 /* command to be executed */
167 struct sshbuf *command;
168
169 /* # of replies received for global requests */
170 static int forward_confirms_pending = -1;
171
172 /* mux.c */
173 extern int muxserver_sock;
174 extern u_int muxclient_command;
175
176 /* Prints a help message to the user.  This function never returns. */
177
178 static void
179 usage(void)
180 {
181         fprintf(stderr,
182 "usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] [-B bind_interface]\n"
183 "           [-b bind_address] [-c cipher_spec] [-D [bind_address:]port]\n"
184 "           [-E log_file] [-e escape_char] [-F configfile] [-I pkcs11]\n"
185 "           [-i identity_file] [-J [user@]host[:port]] [-L address]\n"
186 "           [-l login_name] [-m mac_spec] [-O ctl_cmd] [-o option] [-p port]\n"
187 "           [-Q query_option] [-R address] [-S ctl_path] [-W host:port]\n"
188 "           [-w local_tun[:remote_tun]] destination [command [argument ...]]\n"
189         );
190         exit(255);
191 }
192
193 static int ssh_session2(struct ssh *, const struct ssh_conn_info *);
194 static void load_public_identity_files(const struct ssh_conn_info *);
195 static void main_sigchld_handler(int);
196
197 /* ~/ expand a list of paths. NB. assumes path[n] is heap-allocated. */
198 static void
199 tilde_expand_paths(char **paths, u_int num_paths)
200 {
201         u_int i;
202         char *cp;
203
204         for (i = 0; i < num_paths; i++) {
205                 cp = tilde_expand_filename(paths[i], getuid());
206                 free(paths[i]);
207                 paths[i] = cp;
208         }
209 }
210
211 /*
212  * Expands the set of percent_expand options used by the majority of keywords
213  * in the client that support percent expansion.
214  * Caller must free returned string.
215  */
216 static char *
217 default_client_percent_expand(const char *str,
218     const struct ssh_conn_info *cinfo)
219 {
220         return percent_expand(str,
221             DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
222             (char *)NULL);
223 }
224
225 /*
226  * Expands the set of percent_expand options used by the majority of keywords
227  * AND perform environment variable substitution.
228  * Caller must free returned string.
229  */
230 static char *
231 default_client_percent_dollar_expand(const char *str,
232     const struct ssh_conn_info *cinfo)
233 {
234         char *ret;
235
236         ret = percent_dollar_expand(str,
237             DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
238             (char *)NULL);
239         if (ret == NULL)
240                 fatal("invalid environment variable expansion");
241         return ret;
242 }
243
244 /*
245  * Attempt to resolve a host name / port to a set of addresses and
246  * optionally return any CNAMEs encountered along the way.
247  * Returns NULL on failure.
248  * NB. this function must operate with a options having undefined members.
249  */
250 static struct addrinfo *
251 resolve_host(const char *name, int port, int logerr, char *cname, size_t clen)
252 {
253         char strport[NI_MAXSERV];
254         struct addrinfo hints, *res;
255         int gaierr;
256         LogLevel loglevel = SYSLOG_LEVEL_DEBUG1;
257
258         if (port <= 0)
259                 port = default_ssh_port();
260         if (cname != NULL)
261                 *cname = '\0';
262         debug3_f("lookup %s:%d", name, port);
263
264         snprintf(strport, sizeof strport, "%d", port);
265         memset(&hints, 0, sizeof(hints));
266         hints.ai_family = options.address_family == -1 ?
267             AF_UNSPEC : options.address_family;
268         hints.ai_socktype = SOCK_STREAM;
269         if (cname != NULL)
270                 hints.ai_flags = AI_CANONNAME;
271         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
272                 if (logerr || (gaierr != EAI_NONAME && gaierr != EAI_NODATA))
273                         loglevel = SYSLOG_LEVEL_ERROR;
274                 do_log2(loglevel, "%s: Could not resolve hostname %.100s: %s",
275                     __progname, name, ssh_gai_strerror(gaierr));
276                 return NULL;
277         }
278         if (cname != NULL && res->ai_canonname != NULL) {
279                 if (strlcpy(cname, res->ai_canonname, clen) >= clen) {
280                         error_f("host \"%s\" cname \"%s\" too long (max %lu)",
281                             name,  res->ai_canonname, (u_long)clen);
282                         if (clen > 0)
283                                 *cname = '\0';
284                 }
285         }
286         return res;
287 }
288
289 /* Returns non-zero if name can only be an address and not a hostname */
290 static int
291 is_addr_fast(const char *name)
292 {
293         return (strchr(name, '%') != NULL || strchr(name, ':') != NULL ||
294             strspn(name, "0123456789.") == strlen(name));
295 }
296
297 /* Returns non-zero if name represents a valid, single address */
298 static int
299 is_addr(const char *name)
300 {
301         char strport[NI_MAXSERV];
302         struct addrinfo hints, *res;
303
304         if (is_addr_fast(name))
305                 return 1;
306
307         snprintf(strport, sizeof strport, "%u", default_ssh_port());
308         memset(&hints, 0, sizeof(hints));
309         hints.ai_family = options.address_family == -1 ?
310             AF_UNSPEC : options.address_family;
311         hints.ai_socktype = SOCK_STREAM;
312         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
313         if (getaddrinfo(name, strport, &hints, &res) != 0)
314                 return 0;
315         if (res == NULL || res->ai_next != NULL) {
316                 freeaddrinfo(res);
317                 return 0;
318         }
319         freeaddrinfo(res);
320         return 1;
321 }
322
323 /*
324  * Attempt to resolve a numeric host address / port to a single address.
325  * Returns a canonical address string.
326  * Returns NULL on failure.
327  * NB. this function must operate with a options having undefined members.
328  */
329 static struct addrinfo *
330 resolve_addr(const char *name, int port, char *caddr, size_t clen)
331 {
332         char addr[NI_MAXHOST], strport[NI_MAXSERV];
333         struct addrinfo hints, *res;
334         int gaierr;
335
336         if (port <= 0)
337                 port = default_ssh_port();
338         snprintf(strport, sizeof strport, "%u", port);
339         memset(&hints, 0, sizeof(hints));
340         hints.ai_family = options.address_family == -1 ?
341             AF_UNSPEC : options.address_family;
342         hints.ai_socktype = SOCK_STREAM;
343         hints.ai_flags = AI_NUMERICHOST|AI_NUMERICSERV;
344         if ((gaierr = getaddrinfo(name, strport, &hints, &res)) != 0) {
345                 debug2_f("could not resolve name %.100s as address: %s",
346                     name, ssh_gai_strerror(gaierr));
347                 return NULL;
348         }
349         if (res == NULL) {
350                 debug_f("getaddrinfo %.100s returned no addresses", name);
351                 return NULL;
352         }
353         if (res->ai_next != NULL) {
354                 debug_f("getaddrinfo %.100s returned multiple addresses", name);
355                 goto fail;
356         }
357         if ((gaierr = getnameinfo(res->ai_addr, res->ai_addrlen,
358             addr, sizeof(addr), NULL, 0, NI_NUMERICHOST)) != 0) {
359                 debug_f("Could not format address for name %.100s: %s",
360                     name, ssh_gai_strerror(gaierr));
361                 goto fail;
362         }
363         if (strlcpy(caddr, addr, clen) >= clen) {
364                 error_f("host \"%s\" addr \"%s\" too long (max %lu)",
365                     name,  addr, (u_long)clen);
366                 if (clen > 0)
367                         *caddr = '\0';
368  fail:
369                 freeaddrinfo(res);
370                 return NULL;
371         }
372         return res;
373 }
374
375 /*
376  * Check whether the cname is a permitted replacement for the hostname
377  * and perform the replacement if it is.
378  * NB. this function must operate with a options having undefined members.
379  */
380 static int
381 check_follow_cname(int direct, char **namep, const char *cname)
382 {
383         int i;
384         struct allowed_cname *rule;
385
386         if (*cname == '\0' || !config_has_permitted_cnames(&options) ||
387             strcmp(*namep, cname) == 0)
388                 return 0;
389         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
390                 return 0;
391         /*
392          * Don't attempt to canonicalize names that will be interpreted by
393          * a proxy or jump host unless the user specifically requests so.
394          */
395         if (!direct &&
396             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
397                 return 0;
398         debug3_f("check \"%s\" CNAME \"%s\"", *namep, cname);
399         for (i = 0; i < options.num_permitted_cnames; i++) {
400                 rule = options.permitted_cnames + i;
401                 if (match_pattern_list(*namep, rule->source_list, 1) != 1 ||
402                     match_pattern_list(cname, rule->target_list, 1) != 1)
403                         continue;
404                 verbose("Canonicalized DNS aliased hostname "
405                     "\"%s\" => \"%s\"", *namep, cname);
406                 free(*namep);
407                 *namep = xstrdup(cname);
408                 return 1;
409         }
410         return 0;
411 }
412
413 /*
414  * Attempt to resolve the supplied hostname after applying the user's
415  * canonicalization rules. Returns the address list for the host or NULL
416  * if no name was found after canonicalization.
417  * NB. this function must operate with a options having undefined members.
418  */
419 static struct addrinfo *
420 resolve_canonicalize(char **hostp, int port)
421 {
422         int i, direct, ndots;
423         char *cp, *fullhost, newname[NI_MAXHOST];
424         struct addrinfo *addrs;
425
426         /*
427          * Attempt to canonicalise addresses, regardless of
428          * whether hostname canonicalisation was requested
429          */
430         if ((addrs = resolve_addr(*hostp, port,
431             newname, sizeof(newname))) != NULL) {
432                 debug2_f("hostname %.100s is address", *hostp);
433                 if (strcasecmp(*hostp, newname) != 0) {
434                         debug2_f("canonicalised address \"%s\" => \"%s\"",
435                             *hostp, newname);
436                         free(*hostp);
437                         *hostp = xstrdup(newname);
438                 }
439                 return addrs;
440         }
441
442         /*
443          * If this looks like an address but didn't parse as one, it might
444          * be an address with an invalid interface scope. Skip further
445          * attempts at canonicalisation.
446          */
447         if (is_addr_fast(*hostp)) {
448                 debug_f("hostname %.100s is an unrecognised address", *hostp);
449                 return NULL;
450         }
451
452         if (options.canonicalize_hostname == SSH_CANONICALISE_NO)
453                 return NULL;
454
455         /*
456          * Don't attempt to canonicalize names that will be interpreted by
457          * a proxy unless the user specifically requests so.
458          */
459         direct = option_clear_or_none(options.proxy_command) &&
460             options.jump_host == NULL;
461         if (!direct &&
462             options.canonicalize_hostname != SSH_CANONICALISE_ALWAYS)
463                 return NULL;
464
465         /* If domain name is anchored, then resolve it now */
466         if ((*hostp)[strlen(*hostp) - 1] == '.') {
467                 debug3_f("name is fully qualified");
468                 fullhost = xstrdup(*hostp);
469                 if ((addrs = resolve_host(fullhost, port, 0,
470                     newname, sizeof(newname))) != NULL)
471                         goto found;
472                 free(fullhost);
473                 goto notfound;
474         }
475
476         /* Don't apply canonicalization to sufficiently-qualified hostnames */
477         ndots = 0;
478         for (cp = *hostp; *cp != '\0'; cp++) {
479                 if (*cp == '.')
480                         ndots++;
481         }
482         if (ndots > options.canonicalize_max_dots) {
483                 debug3_f("not canonicalizing hostname \"%s\" (max dots %d)",
484                     *hostp, options.canonicalize_max_dots);
485                 return NULL;
486         }
487         /* Attempt each supplied suffix */
488         for (i = 0; i < options.num_canonical_domains; i++) {
489                 if (strcasecmp(options.canonical_domains[i], "none") == 0)
490                         break;
491                 xasprintf(&fullhost, "%s.%s.", *hostp,
492                     options.canonical_domains[i]);
493                 debug3_f("attempting \"%s\" => \"%s\"", *hostp, fullhost);
494                 if ((addrs = resolve_host(fullhost, port, 0,
495                     newname, sizeof(newname))) == NULL) {
496                         free(fullhost);
497                         continue;
498                 }
499  found:
500                 /* Remove trailing '.' */
501                 fullhost[strlen(fullhost) - 1] = '\0';
502                 /* Follow CNAME if requested */
503                 if (!check_follow_cname(direct, &fullhost, newname)) {
504                         debug("Canonicalized hostname \"%s\" => \"%s\"",
505                             *hostp, fullhost);
506                 }
507                 free(*hostp);
508                 *hostp = fullhost;
509                 return addrs;
510         }
511  notfound:
512         if (!options.canonicalize_fallback_local)
513                 fatal("%s: Could not resolve host \"%s\"", __progname, *hostp);
514         debug2_f("host %s not found in any suffix", *hostp);
515         return NULL;
516 }
517
518 /*
519  * Check the result of hostkey loading, ignoring some errors and either
520  * discarding the key or fatal()ing for others.
521  */
522 static void
523 check_load(int r, struct sshkey **k, const char *path, const char *message)
524 {
525         switch (r) {
526         case 0:
527                 /* Check RSA keys size and discard if undersized */
528                 if (k != NULL && *k != NULL &&
529                     (r = sshkey_check_rsa_length(*k,
530                     options.required_rsa_size)) != 0) {
531                         error_r(r, "load %s \"%s\"", message, path);
532                         free(*k);
533                         *k = NULL;
534                 }
535                 break;
536         case SSH_ERR_INTERNAL_ERROR:
537         case SSH_ERR_ALLOC_FAIL:
538                 fatal_r(r, "load %s \"%s\"", message, path);
539         case SSH_ERR_SYSTEM_ERROR:
540                 /* Ignore missing files */
541                 if (errno == ENOENT)
542                         break;
543                 /* FALLTHROUGH */
544         default:
545                 error_r(r, "load %s \"%s\"", message, path);
546                 break;
547         }
548 }
549
550 /*
551  * Read per-user configuration file.  Ignore the system wide config
552  * file if the user specifies a config file on the command line.
553  */
554 static void
555 process_config_files(const char *host_name, struct passwd *pw, int final_pass,
556     int *want_final_pass)
557 {
558         char buf[PATH_MAX];
559         int r;
560
561         if (config != NULL) {
562                 if (strcasecmp(config, "none") != 0 &&
563                     !read_config_file(config, pw, host, host_name, &options,
564                     SSHCONF_USERCONF | (final_pass ? SSHCONF_FINAL : 0),
565                     want_final_pass))
566                         fatal("Can't open user config file %.100s: "
567                             "%.100s", config, strerror(errno));
568         } else {
569                 r = snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir,
570                     _PATH_SSH_USER_CONFFILE);
571                 if (r > 0 && (size_t)r < sizeof(buf))
572                         (void)read_config_file(buf, pw, host, host_name,
573                             &options, SSHCONF_CHECKPERM | SSHCONF_USERCONF |
574                             (final_pass ? SSHCONF_FINAL : 0), want_final_pass);
575
576                 /* Read systemwide configuration file after user config. */
577                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, pw,
578                     host, host_name, &options,
579                     final_pass ? SSHCONF_FINAL : 0, want_final_pass);
580         }
581 }
582
583 /* Rewrite the port number in an addrinfo list of addresses */
584 static void
585 set_addrinfo_port(struct addrinfo *addrs, int port)
586 {
587         struct addrinfo *addr;
588
589         for (addr = addrs; addr != NULL; addr = addr->ai_next) {
590                 switch (addr->ai_family) {
591                 case AF_INET:
592                         ((struct sockaddr_in *)addr->ai_addr)->
593                             sin_port = htons(port);
594                         break;
595                 case AF_INET6:
596                         ((struct sockaddr_in6 *)addr->ai_addr)->
597                             sin6_port = htons(port);
598                         break;
599                 }
600         }
601 }
602
603 static void
604 ssh_conn_info_free(struct ssh_conn_info *cinfo)
605 {
606         if (cinfo == NULL)
607                 return;
608         free(cinfo->conn_hash_hex);
609         free(cinfo->shorthost);
610         free(cinfo->uidstr);
611         free(cinfo->keyalias);
612         free(cinfo->thishost);
613         free(cinfo->host_arg);
614         free(cinfo->portstr);
615         free(cinfo->remhost);
616         free(cinfo->remuser);
617         free(cinfo->homedir);
618         free(cinfo->locuser);
619         free(cinfo);
620 }
621
622 /*
623  * Main program for the ssh client.
624  */
625 int
626 main(int ac, char **av)
627 {
628         struct ssh *ssh = NULL;
629         int i, r, opt, exit_status, use_syslog, direct, timeout_ms;
630         int was_addr, config_test = 0, opt_terminated = 0, want_final_pass = 0;
631         char *p, *cp, *line, *argv0, *logfile, *host_arg;
632         char cname[NI_MAXHOST], thishost[NI_MAXHOST];
633         struct stat st;
634         struct passwd *pw;
635         extern int optind, optreset;
636         extern char *optarg;
637         struct Forward fwd;
638         struct addrinfo *addrs = NULL;
639         size_t n, len;
640         u_int j;
641         struct ssh_conn_info *cinfo = NULL;
642
643         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
644         sanitise_stdfd();
645
646         /*
647          * Discard other fds that are hanging around. These can cause problem
648          * with backgrounded ssh processes started by ControlPersist.
649          */
650         closefrom(STDERR_FILENO + 1);
651
652         __progname = ssh_get_progname(av[0]);
653
654 #ifndef HAVE_SETPROCTITLE
655         /* Prepare for later setproctitle emulation */
656         /* Save argv so it isn't clobbered by setproctitle() emulation */
657         saved_av = xcalloc(ac + 1, sizeof(*saved_av));
658         for (i = 0; i < ac; i++)
659                 saved_av[i] = xstrdup(av[i]);
660         saved_av[i] = NULL;
661         compat_init_setproctitle(ac, av);
662         av = saved_av;
663 #endif
664
665         seed_rng();
666
667         /* Get user data. */
668         pw = getpwuid(getuid());
669         if (!pw) {
670                 logit("No user exists for uid %lu", (u_long)getuid());
671                 exit(255);
672         }
673         /* Take a copy of the returned structure. */
674         pw = pwcopy(pw);
675
676         /*
677          * Set our umask to something reasonable, as some files are created
678          * with the default umask.  This will make them world-readable but
679          * writable only by the owner, which is ok for all files for which we
680          * don't set the modes explicitly.
681          */
682         umask(022);
683
684         msetlocale();
685
686         /*
687          * Initialize option structure to indicate that no values have been
688          * set.
689          */
690         initialize_options(&options);
691
692         /*
693          * Prepare main ssh transport/connection structures
694          */
695         if ((ssh = ssh_alloc_session_state()) == NULL)
696                 fatal("Couldn't allocate session state");
697         channel_init_channels(ssh);
698
699         /* Parse command-line arguments. */
700         host = NULL;
701         use_syslog = 0;
702         logfile = NULL;
703         argv0 = av[0];
704
705  again:
706         while ((opt = getopt(ac, av, "1246ab:c:e:fgi:kl:m:no:p:qstvx"
707             "AB:CD:E:F:GI:J:KL:MNO:PQ:R:S:TVw:W:XYy")) != -1) { /* HUZdhjruz */
708                 switch (opt) {
709                 case '1':
710                         fatal("SSH protocol v.1 is no longer supported");
711                         break;
712                 case '2':
713                         /* Ignored */
714                         break;
715                 case '4':
716                         options.address_family = AF_INET;
717                         break;
718                 case '6':
719                         options.address_family = AF_INET6;
720                         break;
721                 case 'n':
722                         options.stdin_null = 1;
723                         break;
724                 case 'f':
725                         options.fork_after_authentication = 1;
726                         options.stdin_null = 1;
727                         break;
728                 case 'x':
729                         options.forward_x11 = 0;
730                         break;
731                 case 'X':
732                         options.forward_x11 = 1;
733                         break;
734                 case 'y':
735                         use_syslog = 1;
736                         break;
737                 case 'E':
738                         logfile = optarg;
739                         break;
740                 case 'G':
741                         config_test = 1;
742                         break;
743                 case 'Y':
744                         options.forward_x11 = 1;
745                         options.forward_x11_trusted = 1;
746                         break;
747                 case 'g':
748                         options.fwd_opts.gateway_ports = 1;
749                         break;
750                 case 'O':
751                         if (options.stdio_forward_host != NULL)
752                                 fatal("Cannot specify multiplexing "
753                                     "command with -W");
754                         else if (muxclient_command != 0)
755                                 fatal("Multiplexing command already specified");
756                         if (strcmp(optarg, "check") == 0)
757                                 muxclient_command = SSHMUX_COMMAND_ALIVE_CHECK;
758                         else if (strcmp(optarg, "forward") == 0)
759                                 muxclient_command = SSHMUX_COMMAND_FORWARD;
760                         else if (strcmp(optarg, "exit") == 0)
761                                 muxclient_command = SSHMUX_COMMAND_TERMINATE;
762                         else if (strcmp(optarg, "stop") == 0)
763                                 muxclient_command = SSHMUX_COMMAND_STOP;
764                         else if (strcmp(optarg, "cancel") == 0)
765                                 muxclient_command = SSHMUX_COMMAND_CANCEL_FWD;
766                         else if (strcmp(optarg, "proxy") == 0)
767                                 muxclient_command = SSHMUX_COMMAND_PROXY;
768                         else
769                                 fatal("Invalid multiplex command.");
770                         break;
771                 case 'P':       /* deprecated */
772                         break;
773                 case 'Q':
774                         cp = NULL;
775                         if (strcmp(optarg, "cipher") == 0 ||
776                             strcasecmp(optarg, "Ciphers") == 0)
777                                 cp = cipher_alg_list('\n', 0);
778                         else if (strcmp(optarg, "cipher-auth") == 0)
779                                 cp = cipher_alg_list('\n', 1);
780                         else if (strcmp(optarg, "mac") == 0 ||
781                             strcasecmp(optarg, "MACs") == 0)
782                                 cp = mac_alg_list('\n');
783                         else if (strcmp(optarg, "kex") == 0 ||
784                             strcasecmp(optarg, "KexAlgorithms") == 0)
785                                 cp = kex_alg_list('\n');
786                         else if (strcmp(optarg, "key") == 0)
787                                 cp = sshkey_alg_list(0, 0, 0, '\n');
788                         else if (strcmp(optarg, "key-cert") == 0)
789                                 cp = sshkey_alg_list(1, 0, 0, '\n');
790                         else if (strcmp(optarg, "key-plain") == 0)
791                                 cp = sshkey_alg_list(0, 1, 0, '\n');
792                         else if (strcmp(optarg, "key-sig") == 0 ||
793                             strcasecmp(optarg, "PubkeyAcceptedKeyTypes") == 0 || /* deprecated name */
794                             strcasecmp(optarg, "PubkeyAcceptedAlgorithms") == 0 ||
795                             strcasecmp(optarg, "HostKeyAlgorithms") == 0 ||
796                             strcasecmp(optarg, "HostbasedKeyTypes") == 0 || /* deprecated name */
797                             strcasecmp(optarg, "HostbasedAcceptedKeyTypes") == 0 || /* deprecated name */
798                             strcasecmp(optarg, "HostbasedAcceptedAlgorithms") == 0)
799                                 cp = sshkey_alg_list(0, 0, 1, '\n');
800                         else if (strcmp(optarg, "sig") == 0)
801                                 cp = sshkey_alg_list(0, 1, 1, '\n');
802                         else if (strcmp(optarg, "protocol-version") == 0)
803                                 cp = xstrdup("2");
804                         else if (strcmp(optarg, "compression") == 0) {
805                                 cp = xstrdup(compression_alg_list(0));
806                                 len = strlen(cp);
807                                 for (n = 0; n < len; n++)
808                                         if (cp[n] == ',')
809                                                 cp[n] = '\n';
810                         } else if (strcmp(optarg, "help") == 0) {
811                                 cp = xstrdup(
812                                     "cipher\ncipher-auth\ncompression\nkex\n"
813                                     "key\nkey-cert\nkey-plain\nkey-sig\nmac\n"
814                                     "protocol-version\nsig");
815                         }
816                         if (cp == NULL)
817                                 fatal("Unsupported query \"%s\"", optarg);
818                         printf("%s\n", cp);
819                         free(cp);
820                         exit(0);
821                         break;
822                 case 'a':
823                         options.forward_agent = 0;
824                         break;
825                 case 'A':
826                         options.forward_agent = 1;
827                         break;
828                 case 'k':
829                         options.gss_deleg_creds = 0;
830                         break;
831                 case 'K':
832                         options.gss_authentication = 1;
833                         options.gss_deleg_creds = 1;
834                         break;
835                 case 'i':
836                         p = tilde_expand_filename(optarg, getuid());
837                         if (stat(p, &st) == -1)
838                                 fprintf(stderr, "Warning: Identity file %s "
839                                     "not accessible: %s.\n", p,
840                                     strerror(errno));
841                         else
842                                 add_identity_file(&options, NULL, p, 1);
843                         free(p);
844                         break;
845                 case 'I':
846 #ifdef ENABLE_PKCS11
847                         free(options.pkcs11_provider);
848                         options.pkcs11_provider = xstrdup(optarg);
849 #else
850                         fprintf(stderr, "no support for PKCS#11.\n");
851 #endif
852                         break;
853                 case 'J':
854                         if (options.jump_host != NULL) {
855                                 fatal("Only a single -J option is permitted "
856                                     "(use commas to separate multiple "
857                                     "jump hops)");
858                         }
859                         if (options.proxy_command != NULL)
860                                 fatal("Cannot specify -J with ProxyCommand");
861                         if (parse_jump(optarg, &options, 1) == -1)
862                                 fatal("Invalid -J argument");
863                         options.proxy_command = xstrdup("none");
864                         break;
865                 case 't':
866                         if (options.request_tty == REQUEST_TTY_YES)
867                                 options.request_tty = REQUEST_TTY_FORCE;
868                         else
869                                 options.request_tty = REQUEST_TTY_YES;
870                         break;
871                 case 'v':
872                         if (debug_flag == 0) {
873                                 debug_flag = 1;
874                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
875                         } else {
876                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
877                                         debug_flag++;
878                                         options.log_level++;
879                                 }
880                         }
881                         break;
882                 case 'V':
883                         fprintf(stderr, "%s, %s\n",
884                             SSH_RELEASE, SSH_OPENSSL_VERSION);
885                         if (opt == 'V')
886                                 exit(0);
887                         break;
888                 case 'w':
889                         if (options.tun_open == -1)
890                                 options.tun_open = SSH_TUNMODE_DEFAULT;
891                         options.tun_local = a2tun(optarg, &options.tun_remote);
892                         if (options.tun_local == SSH_TUNID_ERR) {
893                                 fprintf(stderr,
894                                     "Bad tun device '%s'\n", optarg);
895                                 exit(255);
896                         }
897                         break;
898                 case 'W':
899                         if (options.stdio_forward_host != NULL)
900                                 fatal("stdio forward already specified");
901                         if (muxclient_command != 0)
902                                 fatal("Cannot specify stdio forward with -O");
903                         if (parse_forward(&fwd, optarg, 1, 0)) {
904                                 options.stdio_forward_host = fwd.listen_host;
905                                 options.stdio_forward_port = fwd.listen_port;
906                                 free(fwd.connect_host);
907                         } else {
908                                 fprintf(stderr,
909                                     "Bad stdio forwarding specification '%s'\n",
910                                     optarg);
911                                 exit(255);
912                         }
913                         options.request_tty = REQUEST_TTY_NO;
914                         options.session_type = SESSION_TYPE_NONE;
915                         break;
916                 case 'q':
917                         options.log_level = SYSLOG_LEVEL_QUIET;
918                         break;
919                 case 'e':
920                         if (optarg[0] == '^' && optarg[2] == 0 &&
921                             (u_char) optarg[1] >= 64 &&
922                             (u_char) optarg[1] < 128)
923                                 options.escape_char = (u_char) optarg[1] & 31;
924                         else if (strlen(optarg) == 1)
925                                 options.escape_char = (u_char) optarg[0];
926                         else if (strcmp(optarg, "none") == 0)
927                                 options.escape_char = SSH_ESCAPECHAR_NONE;
928                         else {
929                                 fprintf(stderr, "Bad escape character '%s'.\n",
930                                     optarg);
931                                 exit(255);
932                         }
933                         break;
934                 case 'c':
935                         if (!ciphers_valid(*optarg == '+' || *optarg == '^' ?
936                             optarg + 1 : optarg)) {
937                                 fprintf(stderr, "Unknown cipher type '%s'\n",
938                                     optarg);
939                                 exit(255);
940                         }
941                         free(options.ciphers);
942                         options.ciphers = xstrdup(optarg);
943                         break;
944                 case 'm':
945                         if (mac_valid(optarg)) {
946                                 free(options.macs);
947                                 options.macs = xstrdup(optarg);
948                         } else {
949                                 fprintf(stderr, "Unknown mac type '%s'\n",
950                                     optarg);
951                                 exit(255);
952                         }
953                         break;
954                 case 'M':
955                         if (options.control_master == SSHCTL_MASTER_YES)
956                                 options.control_master = SSHCTL_MASTER_ASK;
957                         else
958                                 options.control_master = SSHCTL_MASTER_YES;
959                         break;
960                 case 'p':
961                         if (options.port == -1) {
962                                 options.port = a2port(optarg);
963                                 if (options.port <= 0) {
964                                         fprintf(stderr, "Bad port '%s'\n",
965                                             optarg);
966                                         exit(255);
967                                 }
968                         }
969                         break;
970                 case 'l':
971                         if (options.user == NULL)
972                                 options.user = optarg;
973                         break;
974
975                 case 'L':
976                         if (parse_forward(&fwd, optarg, 0, 0))
977                                 add_local_forward(&options, &fwd);
978                         else {
979                                 fprintf(stderr,
980                                     "Bad local forwarding specification '%s'\n",
981                                     optarg);
982                                 exit(255);
983                         }
984                         break;
985
986                 case 'R':
987                         if (parse_forward(&fwd, optarg, 0, 1) ||
988                             parse_forward(&fwd, optarg, 1, 1)) {
989                                 add_remote_forward(&options, &fwd);
990                         } else {
991                                 fprintf(stderr,
992                                     "Bad remote forwarding specification "
993                                     "'%s'\n", optarg);
994                                 exit(255);
995                         }
996                         break;
997
998                 case 'D':
999                         if (parse_forward(&fwd, optarg, 1, 0)) {
1000                                 add_local_forward(&options, &fwd);
1001                         } else {
1002                                 fprintf(stderr,
1003                                     "Bad dynamic forwarding specification "
1004                                     "'%s'\n", optarg);
1005                                 exit(255);
1006                         }
1007                         break;
1008
1009                 case 'C':
1010 #ifdef WITH_ZLIB
1011                         options.compression = 1;
1012 #else
1013                         error("Compression not supported, disabling.");
1014 #endif
1015                         break;
1016                 case 'N':
1017                         if (options.session_type != -1 &&
1018                             options.session_type != SESSION_TYPE_NONE)
1019                                 fatal("Cannot specify -N with -s/SessionType");
1020                         options.session_type = SESSION_TYPE_NONE;
1021                         options.request_tty = REQUEST_TTY_NO;
1022                         break;
1023                 case 'T':
1024                         options.request_tty = REQUEST_TTY_NO;
1025                         break;
1026                 case 'o':
1027                         line = xstrdup(optarg);
1028                         if (process_config_line(&options, pw,
1029                             host ? host : "", host ? host : "", line,
1030                             "command-line", 0, NULL, SSHCONF_USERCONF) != 0)
1031                                 exit(255);
1032                         free(line);
1033                         break;
1034                 case 's':
1035                         if (options.session_type != -1 &&
1036                             options.session_type != SESSION_TYPE_SUBSYSTEM)
1037                                 fatal("Cannot specify -s with -N/SessionType");
1038                         options.session_type = SESSION_TYPE_SUBSYSTEM;
1039                         break;
1040                 case 'S':
1041                         free(options.control_path);
1042                         options.control_path = xstrdup(optarg);
1043                         break;
1044                 case 'b':
1045                         options.bind_address = optarg;
1046                         break;
1047                 case 'B':
1048                         options.bind_interface = optarg;
1049                         break;
1050                 case 'F':
1051                         config = optarg;
1052                         break;
1053                 default:
1054                         usage();
1055                 }
1056         }
1057
1058         if (optind > 1 && strcmp(av[optind - 1], "--") == 0)
1059                 opt_terminated = 1;
1060
1061         ac -= optind;
1062         av += optind;
1063
1064         if (ac > 0 && !host) {
1065                 int tport;
1066                 char *tuser;
1067                 switch (parse_ssh_uri(*av, &tuser, &host, &tport)) {
1068                 case -1:
1069                         usage();
1070                         break;
1071                 case 0:
1072                         if (options.user == NULL) {
1073                                 options.user = tuser;
1074                                 tuser = NULL;
1075                         }
1076                         free(tuser);
1077                         if (options.port == -1 && tport != -1)
1078                                 options.port = tport;
1079                         break;
1080                 default:
1081                         p = xstrdup(*av);
1082                         cp = strrchr(p, '@');
1083                         if (cp != NULL) {
1084                                 if (cp == p)
1085                                         usage();
1086                                 if (options.user == NULL) {
1087                                         options.user = p;
1088                                         p = NULL;
1089                                 }
1090                                 *cp++ = '\0';
1091                                 host = xstrdup(cp);
1092                                 free(p);
1093                         } else
1094                                 host = p;
1095                         break;
1096                 }
1097                 if (ac > 1 && !opt_terminated) {
1098                         optind = optreset = 1;
1099                         goto again;
1100                 }
1101                 ac--, av++;
1102         }
1103
1104         /* Check that we got a host name. */
1105         if (!host)
1106                 usage();
1107
1108         host_arg = xstrdup(host);
1109
1110         /* Initialize the command to execute on remote host. */
1111         if ((command = sshbuf_new()) == NULL)
1112                 fatal("sshbuf_new failed");
1113
1114         /*
1115          * Save the command to execute on the remote host in a buffer. There
1116          * is no limit on the length of the command, except by the maximum
1117          * packet size.  Also sets the tty flag if there is no command.
1118          */
1119         if (!ac) {
1120                 /* No command specified - execute shell on a tty. */
1121                 if (options.session_type == SESSION_TYPE_SUBSYSTEM) {
1122                         fprintf(stderr,
1123                             "You must specify a subsystem to invoke.\n");
1124                         usage();
1125                 }
1126         } else {
1127                 /* A command has been specified.  Store it into the buffer. */
1128                 for (i = 0; i < ac; i++) {
1129                         if ((r = sshbuf_putf(command, "%s%s",
1130                             i ? " " : "", av[i])) != 0)
1131                                 fatal_fr(r, "buffer error");
1132                 }
1133         }
1134
1135         ssh_signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
1136
1137         /*
1138          * Initialize "log" output.  Since we are the client all output
1139          * goes to stderr unless otherwise specified by -y or -E.
1140          */
1141         if (use_syslog && logfile != NULL)
1142                 fatal("Can't specify both -y and -E");
1143         if (logfile != NULL)
1144                 log_redirect_stderr_to(logfile);
1145         log_init(argv0,
1146             options.log_level == SYSLOG_LEVEL_NOT_SET ?
1147             SYSLOG_LEVEL_INFO : options.log_level,
1148             options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1149             SYSLOG_FACILITY_USER : options.log_facility,
1150             !use_syslog);
1151
1152         if (debug_flag)
1153                 logit("%s, %s", SSH_RELEASE, SSH_OPENSSL_VERSION);
1154
1155         /* Parse the configuration files */
1156         process_config_files(host_arg, pw, 0, &want_final_pass);
1157         if (want_final_pass)
1158                 debug("configuration requests final Match pass");
1159
1160         /* Hostname canonicalisation needs a few options filled. */
1161         fill_default_options_for_canonicalization(&options);
1162
1163         /* If the user has replaced the hostname then take it into use now */
1164         if (options.hostname != NULL) {
1165                 /* NB. Please keep in sync with readconf.c:match_cfg_line() */
1166                 cp = percent_expand(options.hostname,
1167                     "h", host, (char *)NULL);
1168                 free(host);
1169                 host = cp;
1170                 free(options.hostname);
1171                 options.hostname = xstrdup(host);
1172         }
1173
1174         /* Don't lowercase addresses, they will be explicitly canonicalised */
1175         if ((was_addr = is_addr(host)) == 0)
1176                 lowercase(host);
1177
1178         /*
1179          * Try to canonicalize if requested by configuration or the
1180          * hostname is an address.
1181          */
1182         if (options.canonicalize_hostname != SSH_CANONICALISE_NO || was_addr)
1183                 addrs = resolve_canonicalize(&host, options.port);
1184
1185         /*
1186          * If CanonicalizePermittedCNAMEs have been specified but
1187          * other canonicalization did not happen (by not being requested
1188          * or by failing with fallback) then the hostname may still be changed
1189          * as a result of CNAME following.
1190          *
1191          * Try to resolve the bare hostname name using the system resolver's
1192          * usual search rules and then apply the CNAME follow rules.
1193          *
1194          * Skip the lookup if a ProxyCommand is being used unless the user
1195          * has specifically requested canonicalisation for this case via
1196          * CanonicalizeHostname=always
1197          */
1198         direct = option_clear_or_none(options.proxy_command) &&
1199             options.jump_host == NULL;
1200         if (addrs == NULL && config_has_permitted_cnames(&options) && (direct ||
1201             options.canonicalize_hostname == SSH_CANONICALISE_ALWAYS)) {
1202                 if ((addrs = resolve_host(host, options.port,
1203                     direct, cname, sizeof(cname))) == NULL) {
1204                         /* Don't fatal proxied host names not in the DNS */
1205                         if (direct)
1206                                 cleanup_exit(255); /* logged in resolve_host */
1207                 } else
1208                         check_follow_cname(direct, &host, cname);
1209         }
1210
1211         /*
1212          * If canonicalisation is enabled then re-parse the configuration
1213          * files as new stanzas may match.
1214          */
1215         if (options.canonicalize_hostname != 0 && !want_final_pass) {
1216                 debug("hostname canonicalisation enabled, "
1217                     "will re-parse configuration");
1218                 want_final_pass = 1;
1219         }
1220
1221         if (want_final_pass) {
1222                 debug("re-parsing configuration");
1223                 free(options.hostname);
1224                 options.hostname = xstrdup(host);
1225                 process_config_files(host_arg, pw, 1, NULL);
1226                 /*
1227                  * Address resolution happens early with canonicalisation
1228                  * enabled and the port number may have changed since, so
1229                  * reset it in address list
1230                  */
1231                 if (addrs != NULL && options.port > 0)
1232                         set_addrinfo_port(addrs, options.port);
1233         }
1234
1235         /* Fill configuration defaults. */
1236         if (fill_default_options(&options) != 0)
1237                 cleanup_exit(255);
1238
1239         if (options.user == NULL)
1240                 options.user = xstrdup(pw->pw_name);
1241
1242         /*
1243          * If ProxyJump option specified, then construct a ProxyCommand now.
1244          */
1245         if (options.jump_host != NULL) {
1246                 char port_s[8];
1247                 const char *jumpuser = options.jump_user, *sshbin = argv0;
1248                 int port = options.port, jumpport = options.jump_port;
1249
1250                 if (port <= 0)
1251                         port = default_ssh_port();
1252                 if (jumpport <= 0)
1253                         jumpport = default_ssh_port();
1254                 if (jumpuser == NULL)
1255                         jumpuser = options.user;
1256                 if (strcmp(options.jump_host, host) == 0 && port == jumpport &&
1257                     strcmp(options.user, jumpuser) == 0)
1258                         fatal("jumphost loop via %s", options.jump_host);
1259
1260                 /*
1261                  * Try to use SSH indicated by argv[0], but fall back to
1262                  * "ssh" if it appears unavailable.
1263                  */
1264                 if (strchr(argv0, '/') != NULL && access(argv0, X_OK) != 0)
1265                         sshbin = "ssh";
1266
1267                 /* Consistency check */
1268                 if (options.proxy_command != NULL)
1269                         fatal("inconsistent options: ProxyCommand+ProxyJump");
1270                 /* Never use FD passing for ProxyJump */
1271                 options.proxy_use_fdpass = 0;
1272                 snprintf(port_s, sizeof(port_s), "%d", options.jump_port);
1273                 xasprintf(&options.proxy_command,
1274                     "%s%s%s%s%s%s%s%s%s%s%.*s -W '[%%h]:%%p' %s",
1275                     sshbin,
1276                     /* Optional "-l user" argument if jump_user set */
1277                     options.jump_user == NULL ? "" : " -l ",
1278                     options.jump_user == NULL ? "" : options.jump_user,
1279                     /* Optional "-p port" argument if jump_port set */
1280                     options.jump_port <= 0 ? "" : " -p ",
1281                     options.jump_port <= 0 ? "" : port_s,
1282                     /* Optional additional jump hosts ",..." */
1283                     options.jump_extra == NULL ? "" : " -J ",
1284                     options.jump_extra == NULL ? "" : options.jump_extra,
1285                     /* Optional "-F" argument if -F specified */
1286                     config == NULL ? "" : " -F ",
1287                     config == NULL ? "" : config,
1288                     /* Optional "-v" arguments if -v set */
1289                     debug_flag ? " -" : "",
1290                     debug_flag, "vvv",
1291                     /* Mandatory hostname */
1292                     options.jump_host);
1293                 debug("Setting implicit ProxyCommand from ProxyJump: %s",
1294                     options.proxy_command);
1295         }
1296
1297         if (options.port == 0)
1298                 options.port = default_ssh_port();
1299         channel_set_af(ssh, options.address_family);
1300
1301         /* Tidy and check options */
1302         if (options.host_key_alias != NULL)
1303                 lowercase(options.host_key_alias);
1304         if (options.proxy_command != NULL &&
1305             strcmp(options.proxy_command, "-") == 0 &&
1306             options.proxy_use_fdpass)
1307                 fatal("ProxyCommand=- and ProxyUseFDPass are incompatible");
1308         if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
1309                 if (options.control_persist && options.control_path != NULL) {
1310                         debug("UpdateHostKeys=ask is incompatible with "
1311                             "ControlPersist; disabling");
1312                         options.update_hostkeys = 0;
1313                 } else if (sshbuf_len(command) != 0 ||
1314                     options.remote_command != NULL ||
1315                     options.request_tty == REQUEST_TTY_NO) {
1316                         debug("UpdateHostKeys=ask is incompatible with "
1317                             "remote command execution; disabling");
1318                         options.update_hostkeys = 0;
1319                 } else if (options.log_level < SYSLOG_LEVEL_INFO) {
1320                         /* no point logging anything; user won't see it */
1321                         options.update_hostkeys = 0;
1322                 }
1323         }
1324         if (options.connection_attempts <= 0)
1325                 fatal("Invalid number of ConnectionAttempts");
1326
1327         if (sshbuf_len(command) != 0 && options.remote_command != NULL)
1328                 fatal("Cannot execute command-line and remote command.");
1329
1330         /* Cannot fork to background if no command. */
1331         if (options.fork_after_authentication && sshbuf_len(command) == 0 &&
1332             options.remote_command == NULL &&
1333             options.session_type != SESSION_TYPE_NONE)
1334                 fatal("Cannot fork into background without a command "
1335                     "to execute.");
1336
1337         /* reinit */
1338         log_init(argv0, options.log_level, options.log_facility, !use_syslog);
1339         for (j = 0; j < options.num_log_verbose; j++) {
1340                 if (strcasecmp(options.log_verbose[j], "none") == 0)
1341                         break;
1342                 log_verbose_add(options.log_verbose[j]);
1343         }
1344
1345         if (options.request_tty == REQUEST_TTY_YES ||
1346             options.request_tty == REQUEST_TTY_FORCE)
1347                 tty_flag = 1;
1348
1349         /* Allocate a tty by default if no command specified. */
1350         if (sshbuf_len(command) == 0 && options.remote_command == NULL)
1351                 tty_flag = options.request_tty != REQUEST_TTY_NO;
1352
1353         /* Force no tty */
1354         if (options.request_tty == REQUEST_TTY_NO ||
1355             (muxclient_command && muxclient_command != SSHMUX_COMMAND_PROXY) ||
1356             options.session_type == SESSION_TYPE_NONE)
1357                 tty_flag = 0;
1358         /* Do not allocate a tty if stdin is not a tty. */
1359         if ((!isatty(fileno(stdin)) || options.stdin_null) &&
1360             options.request_tty != REQUEST_TTY_FORCE) {
1361                 if (tty_flag)
1362                         logit("Pseudo-terminal will not be allocated because "
1363                             "stdin is not a terminal.");
1364                 tty_flag = 0;
1365         }
1366
1367         /* Set up strings used to percent_expand() arguments */
1368         cinfo = xcalloc(1, sizeof(*cinfo));
1369         if (gethostname(thishost, sizeof(thishost)) == -1)
1370                 fatal("gethostname: %s", strerror(errno));
1371         cinfo->thishost = xstrdup(thishost);
1372         thishost[strcspn(thishost, ".")] = '\0';
1373         cinfo->shorthost = xstrdup(thishost);
1374         xasprintf(&cinfo->portstr, "%d", options.port);
1375         xasprintf(&cinfo->uidstr, "%llu",
1376             (unsigned long long)pw->pw_uid);
1377         cinfo->keyalias = xstrdup(options.host_key_alias ?
1378             options.host_key_alias : host_arg);
1379         cinfo->conn_hash_hex = ssh_connection_hash(cinfo->thishost, host,
1380             cinfo->portstr, options.user);
1381         cinfo->host_arg = xstrdup(host_arg);
1382         cinfo->remhost = xstrdup(host);
1383         cinfo->remuser = xstrdup(options.user);
1384         cinfo->homedir = xstrdup(pw->pw_dir);
1385         cinfo->locuser = xstrdup(pw->pw_name);
1386
1387         /* Find canonic host name. */
1388         if (strchr(host, '.') == 0) {
1389                 struct addrinfo hints;
1390                 struct addrinfo *ai = NULL;
1391                 int errgai;
1392                 memset(&hints, 0, sizeof(hints));
1393                 hints.ai_family = options.address_family;
1394                 hints.ai_flags = AI_CANONNAME;
1395                 hints.ai_socktype = SOCK_STREAM;
1396                 errgai = getaddrinfo(host, NULL, &hints, &ai);
1397                 if (errgai == 0) {
1398                         if (ai->ai_canonname != NULL)
1399                                 host = xstrdup(ai->ai_canonname);
1400                         freeaddrinfo(ai);
1401                 }
1402         }
1403
1404         /*
1405          * Expand tokens in arguments. NB. LocalCommand is expanded later,
1406          * after port-forwarding is set up, so it may pick up any local
1407          * tunnel interface name allocated.
1408          */
1409         if (options.remote_command != NULL) {
1410                 debug3("expanding RemoteCommand: %s", options.remote_command);
1411                 cp = options.remote_command;
1412                 options.remote_command = default_client_percent_expand(cp,
1413                     cinfo);
1414                 debug3("expanded RemoteCommand: %s", options.remote_command);
1415                 free(cp);
1416                 if ((r = sshbuf_put(command, options.remote_command,
1417                     strlen(options.remote_command))) != 0)
1418                         fatal_fr(r, "buffer error");
1419         }
1420
1421         if (options.control_path != NULL) {
1422                 cp = tilde_expand_filename(options.control_path, getuid());
1423                 free(options.control_path);
1424                 options.control_path = default_client_percent_dollar_expand(cp,
1425                     cinfo);
1426                 free(cp);
1427         }
1428
1429         if (options.identity_agent != NULL) {
1430                 p = tilde_expand_filename(options.identity_agent, getuid());
1431                 cp = default_client_percent_dollar_expand(p, cinfo);
1432                 free(p);
1433                 free(options.identity_agent);
1434                 options.identity_agent = cp;
1435         }
1436
1437         if (options.forward_agent_sock_path != NULL) {
1438                 p = tilde_expand_filename(options.forward_agent_sock_path,
1439                     getuid());
1440                 cp = default_client_percent_dollar_expand(p, cinfo);
1441                 free(p);
1442                 free(options.forward_agent_sock_path);
1443                 options.forward_agent_sock_path = cp;
1444                 if (stat(options.forward_agent_sock_path, &st) != 0) {
1445                         error("Cannot forward agent socket path \"%s\": %s",
1446                             options.forward_agent_sock_path, strerror(errno));
1447                         if (options.exit_on_forward_failure)
1448                                 cleanup_exit(255);
1449                 }
1450         }
1451
1452         if (options.num_system_hostfiles > 0 &&
1453             strcasecmp(options.system_hostfiles[0], "none") == 0) {
1454                 if (options.num_system_hostfiles > 1)
1455                         fatal("Invalid GlobalKnownHostsFiles: \"none\" "
1456                             "appears with other entries");
1457                 free(options.system_hostfiles[0]);
1458                 options.system_hostfiles[0] = NULL;
1459                 options.num_system_hostfiles = 0;
1460         }
1461
1462         if (options.num_user_hostfiles > 0 &&
1463             strcasecmp(options.user_hostfiles[0], "none") == 0) {
1464                 if (options.num_user_hostfiles > 1)
1465                         fatal("Invalid UserKnownHostsFiles: \"none\" "
1466                             "appears with other entries");
1467                 free(options.user_hostfiles[0]);
1468                 options.user_hostfiles[0] = NULL;
1469                 options.num_user_hostfiles = 0;
1470         }
1471         for (j = 0; j < options.num_user_hostfiles; j++) {
1472                 if (options.user_hostfiles[j] == NULL)
1473                         continue;
1474                 cp = tilde_expand_filename(options.user_hostfiles[j], getuid());
1475                 p = default_client_percent_dollar_expand(cp, cinfo);
1476                 if (strcmp(options.user_hostfiles[j], p) != 0)
1477                         debug3("expanded UserKnownHostsFile '%s' -> "
1478                             "'%s'", options.user_hostfiles[j], p);
1479                 free(options.user_hostfiles[j]);
1480                 free(cp);
1481                 options.user_hostfiles[j] = p;
1482         }
1483
1484         for (i = 0; i < options.num_local_forwards; i++) {
1485                 if (options.local_forwards[i].listen_path != NULL) {
1486                         cp = options.local_forwards[i].listen_path;
1487                         p = options.local_forwards[i].listen_path =
1488                             default_client_percent_expand(cp, cinfo);
1489                         if (strcmp(cp, p) != 0)
1490                                 debug3("expanded LocalForward listen path "
1491                                     "'%s' -> '%s'", cp, p);
1492                         free(cp);
1493                 }
1494                 if (options.local_forwards[i].connect_path != NULL) {
1495                         cp = options.local_forwards[i].connect_path;
1496                         p = options.local_forwards[i].connect_path =
1497                             default_client_percent_expand(cp, cinfo);
1498                         if (strcmp(cp, p) != 0)
1499                                 debug3("expanded LocalForward connect path "
1500                                     "'%s' -> '%s'", cp, p);
1501                         free(cp);
1502                 }
1503         }
1504
1505         for (i = 0; i < options.num_remote_forwards; i++) {
1506                 if (options.remote_forwards[i].listen_path != NULL) {
1507                         cp = options.remote_forwards[i].listen_path;
1508                         p = options.remote_forwards[i].listen_path =
1509                             default_client_percent_expand(cp, cinfo);
1510                         if (strcmp(cp, p) != 0)
1511                                 debug3("expanded RemoteForward listen path "
1512                                     "'%s' -> '%s'", cp, p);
1513                         free(cp);
1514                 }
1515                 if (options.remote_forwards[i].connect_path != NULL) {
1516                         cp = options.remote_forwards[i].connect_path;
1517                         p = options.remote_forwards[i].connect_path =
1518                             default_client_percent_expand(cp, cinfo);
1519                         if (strcmp(cp, p) != 0)
1520                                 debug3("expanded RemoteForward connect path "
1521                                     "'%s' -> '%s'", cp, p);
1522                         free(cp);
1523                 }
1524         }
1525
1526         if (config_test) {
1527                 dump_client_config(&options, host);
1528                 exit(0);
1529         }
1530
1531         /* Expand SecurityKeyProvider if it refers to an environment variable */
1532         if (options.sk_provider != NULL && *options.sk_provider == '$' &&
1533             strlen(options.sk_provider) > 1) {
1534                 if ((cp = getenv(options.sk_provider + 1)) == NULL) {
1535                         debug("Authenticator provider %s did not resolve; "
1536                             "disabling", options.sk_provider);
1537                         free(options.sk_provider);
1538                         options.sk_provider = NULL;
1539                 } else {
1540                         debug2("resolved SecurityKeyProvider %s => %s",
1541                             options.sk_provider, cp);
1542                         free(options.sk_provider);
1543                         options.sk_provider = xstrdup(cp);
1544                 }
1545         }
1546
1547         if (muxclient_command != 0 && options.control_path == NULL)
1548                 fatal("No ControlPath specified for \"-O\" command");
1549         if (options.control_path != NULL) {
1550                 int sock;
1551                 if ((sock = muxclient(options.control_path)) >= 0) {
1552                         ssh_packet_set_connection(ssh, sock, sock);
1553                         ssh_packet_set_mux(ssh);
1554                         goto skip_connect;
1555                 }
1556         }
1557
1558         /*
1559          * If hostname canonicalisation was not enabled, then we may not
1560          * have yet resolved the hostname. Do so now.
1561          */
1562         if (addrs == NULL && options.proxy_command == NULL) {
1563                 debug2("resolving \"%s\" port %d", host, options.port);
1564                 if ((addrs = resolve_host(host, options.port, 1,
1565                     cname, sizeof(cname))) == NULL)
1566                         cleanup_exit(255); /* resolve_host logs the error */
1567         }
1568
1569         if (options.connection_timeout >= INT_MAX/1000)
1570                 timeout_ms = INT_MAX;
1571         else
1572                 timeout_ms = options.connection_timeout * 1000;
1573
1574         /* Open a connection to the remote host. */
1575         if (ssh_connect(ssh, host, host_arg, addrs, &hostaddr, options.port,
1576             options.connection_attempts,
1577             &timeout_ms, options.tcp_keep_alive) != 0)
1578                 exit(255);
1579
1580         if (addrs != NULL)
1581                 freeaddrinfo(addrs);
1582
1583         ssh_packet_set_timeout(ssh, options.server_alive_interval,
1584             options.server_alive_count_max);
1585
1586         if (timeout_ms > 0)
1587                 debug3("timeout: %d ms remain after connect", timeout_ms);
1588
1589         /*
1590          * If we successfully made the connection and we have hostbased auth
1591          * enabled, load the public keys so we can later use the ssh-keysign
1592          * helper to sign challenges.
1593          */
1594         sensitive_data.nkeys = 0;
1595         sensitive_data.keys = NULL;
1596         if (options.hostbased_authentication) {
1597                 sensitive_data.nkeys = 10;
1598                 sensitive_data.keys = xcalloc(sensitive_data.nkeys,
1599                     sizeof(struct sshkey));
1600
1601                 /* XXX check errors? */
1602 #define L_PUBKEY(p,o) do { \
1603         if ((o) >= sensitive_data.nkeys) \
1604                 fatal_f("pubkey out of array bounds"); \
1605         check_load(sshkey_load_public(p, &(sensitive_data.keys[o]), NULL), \
1606             &(sensitive_data.keys[o]), p, "pubkey"); \
1607         if (sensitive_data.keys[o] != NULL) \
1608                 debug2("hostbased key %d: %s key from \"%s\"", o, \
1609                     sshkey_ssh_name(sensitive_data.keys[o]), p); \
1610 } while (0)
1611 #define L_CERT(p,o) do { \
1612         if ((o) >= sensitive_data.nkeys) \
1613                 fatal_f("cert out of array bounds"); \
1614         check_load(sshkey_load_cert(p, &(sensitive_data.keys[o])), \
1615             &(sensitive_data.keys[o]), p, "cert"); \
1616         if (sensitive_data.keys[o] != NULL) \
1617                 debug2("hostbased key %d: %s cert from \"%s\"", o, \
1618                     sshkey_ssh_name(sensitive_data.keys[o]), p); \
1619 } while (0)
1620
1621                 if (options.hostbased_authentication == 1) {
1622                         L_CERT(_PATH_HOST_ECDSA_KEY_FILE, 0);
1623                         L_CERT(_PATH_HOST_ED25519_KEY_FILE, 1);
1624                         L_CERT(_PATH_HOST_RSA_KEY_FILE, 2);
1625                         L_CERT(_PATH_HOST_DSA_KEY_FILE, 3);
1626                         L_PUBKEY(_PATH_HOST_ECDSA_KEY_FILE, 4);
1627                         L_PUBKEY(_PATH_HOST_ED25519_KEY_FILE, 5);
1628                         L_PUBKEY(_PATH_HOST_RSA_KEY_FILE, 6);
1629                         L_PUBKEY(_PATH_HOST_DSA_KEY_FILE, 7);
1630                         L_CERT(_PATH_HOST_XMSS_KEY_FILE, 8);
1631                         L_PUBKEY(_PATH_HOST_XMSS_KEY_FILE, 9);
1632                 }
1633         }
1634
1635         /* load options.identity_files */
1636         load_public_identity_files(cinfo);
1637
1638         /* optionally set the SSH_AUTHSOCKET_ENV_NAME variable */
1639         if (options.identity_agent &&
1640             strcmp(options.identity_agent, SSH_AUTHSOCKET_ENV_NAME) != 0) {
1641                 if (strcmp(options.identity_agent, "none") == 0) {
1642                         unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1643                 } else {
1644                         cp = options.identity_agent;
1645                         /* legacy (limited) format */
1646                         if (cp[0] == '$' && cp[1] != '{') {
1647                                 if (!valid_env_name(cp + 1)) {
1648                                         fatal("Invalid IdentityAgent "
1649                                             "environment variable name %s", cp);
1650                                 }
1651                                 if ((p = getenv(cp + 1)) == NULL)
1652                                         unsetenv(SSH_AUTHSOCKET_ENV_NAME);
1653                                 else
1654                                         setenv(SSH_AUTHSOCKET_ENV_NAME, p, 1);
1655                         } else {
1656                                 /* identity_agent specifies a path directly */
1657                                 setenv(SSH_AUTHSOCKET_ENV_NAME, cp, 1);
1658                         }
1659                 }
1660         }
1661
1662         if (options.forward_agent && options.forward_agent_sock_path != NULL) {
1663                 cp = options.forward_agent_sock_path;
1664                 if (cp[0] == '$') {
1665                         if (!valid_env_name(cp + 1)) {
1666                                 fatal("Invalid ForwardAgent environment variable name %s", cp);
1667                         }
1668                         if ((p = getenv(cp + 1)) != NULL)
1669                                 forward_agent_sock_path = xstrdup(p);
1670                         else
1671                                 options.forward_agent = 0;
1672                         free(cp);
1673                 } else {
1674                         forward_agent_sock_path = cp;
1675                 }
1676         }
1677
1678         /* Expand ~ in known host file names. */
1679         tilde_expand_paths(options.system_hostfiles,
1680             options.num_system_hostfiles);
1681         tilde_expand_paths(options.user_hostfiles, options.num_user_hostfiles);
1682
1683         ssh_signal(SIGCHLD, main_sigchld_handler);
1684
1685         /* Log into the remote system.  Never returns if the login fails. */
1686         ssh_login(ssh, &sensitive_data, host, (struct sockaddr *)&hostaddr,
1687             options.port, pw, timeout_ms, cinfo);
1688
1689         /* We no longer need the private host keys.  Clear them now. */
1690         if (sensitive_data.nkeys != 0) {
1691                 for (i = 0; i < sensitive_data.nkeys; i++) {
1692                         if (sensitive_data.keys[i] != NULL) {
1693                                 /* Destroys contents safely */
1694                                 debug3("clear hostkey %d", i);
1695                                 sshkey_free(sensitive_data.keys[i]);
1696                                 sensitive_data.keys[i] = NULL;
1697                         }
1698                 }
1699                 free(sensitive_data.keys);
1700         }
1701         for (i = 0; i < options.num_identity_files; i++) {
1702                 free(options.identity_files[i]);
1703                 options.identity_files[i] = NULL;
1704                 if (options.identity_keys[i]) {
1705                         sshkey_free(options.identity_keys[i]);
1706                         options.identity_keys[i] = NULL;
1707                 }
1708         }
1709         for (i = 0; i < options.num_certificate_files; i++) {
1710                 free(options.certificate_files[i]);
1711                 options.certificate_files[i] = NULL;
1712         }
1713
1714 #ifdef ENABLE_PKCS11
1715         (void)pkcs11_del_provider(options.pkcs11_provider);
1716 #endif
1717
1718  skip_connect:
1719         exit_status = ssh_session2(ssh, cinfo);
1720         ssh_conn_info_free(cinfo);
1721         ssh_packet_close(ssh);
1722
1723         if (options.control_path != NULL && muxserver_sock != -1)
1724                 unlink(options.control_path);
1725
1726         /* Kill ProxyCommand if it is running. */
1727         ssh_kill_proxy_command();
1728
1729         return exit_status;
1730 }
1731
1732 static void
1733 control_persist_detach(void)
1734 {
1735         pid_t pid;
1736
1737         debug_f("backgrounding master process");
1738
1739         /*
1740          * master (current process) into the background, and make the
1741          * foreground process a client of the backgrounded master.
1742          */
1743         switch ((pid = fork())) {
1744         case -1:
1745                 fatal_f("fork: %s", strerror(errno));
1746         case 0:
1747                 /* Child: master process continues mainloop */
1748                 break;
1749         default:
1750                 /* Parent: set up mux client to connect to backgrounded master */
1751                 debug2_f("background process is %ld", (long)pid);
1752                 options.stdin_null = ostdin_null_flag;
1753                 options.request_tty = orequest_tty;
1754                 tty_flag = otty_flag;
1755                 options.session_type = osession_type;
1756                 close(muxserver_sock);
1757                 muxserver_sock = -1;
1758                 options.control_master = SSHCTL_MASTER_NO;
1759                 muxclient(options.control_path);
1760                 /* muxclient() doesn't return on success. */
1761                 fatal("Failed to connect to new control master");
1762         }
1763         if (stdfd_devnull(1, 1, !(log_is_on_stderr() && debug_flag)) == -1)
1764                 error_f("stdfd_devnull failed");
1765         daemon(1, 1);
1766         setproctitle("%s [mux]", options.control_path);
1767 }
1768
1769 /* Do fork() after authentication. Used by "ssh -f" */
1770 static void
1771 fork_postauth(void)
1772 {
1773         if (need_controlpersist_detach)
1774                 control_persist_detach();
1775         debug("forking to background");
1776         options.fork_after_authentication = 0;
1777         if (daemon(1, 1) == -1)
1778                 fatal("daemon() failed: %.200s", strerror(errno));
1779         if (stdfd_devnull(1, 1, !(log_is_on_stderr() && debug_flag)) == -1)
1780                 error_f("stdfd_devnull failed");
1781 }
1782
1783 static void
1784 forwarding_success(void)
1785 {
1786         if (forward_confirms_pending == -1)
1787                 return;
1788         if (--forward_confirms_pending == 0) {
1789                 debug_f("all expected forwarding replies received");
1790                 if (options.fork_after_authentication)
1791                         fork_postauth();
1792         } else {
1793                 debug2_f("%d expected forwarding replies remaining",
1794                     forward_confirms_pending);
1795         }
1796 }
1797
1798 /* Callback for remote forward global requests */
1799 static void
1800 ssh_confirm_remote_forward(struct ssh *ssh, int type, u_int32_t seq, void *ctxt)
1801 {
1802         struct Forward *rfwd = (struct Forward *)ctxt;
1803         u_int port;
1804         int r;
1805
1806         /* XXX verbose() on failure? */
1807         debug("remote forward %s for: listen %s%s%d, connect %s:%d",
1808             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1809             rfwd->listen_path ? rfwd->listen_path :
1810             rfwd->listen_host ? rfwd->listen_host : "",
1811             (rfwd->listen_path || rfwd->listen_host) ? ":" : "",
1812             rfwd->listen_port, rfwd->connect_path ? rfwd->connect_path :
1813             rfwd->connect_host, rfwd->connect_port);
1814         if (rfwd->listen_path == NULL && rfwd->listen_port == 0) {
1815                 if (type == SSH2_MSG_REQUEST_SUCCESS) {
1816                         if ((r = sshpkt_get_u32(ssh, &port)) != 0)
1817                                 fatal_fr(r, "parse packet");
1818                         if (port > 65535) {
1819                                 error("Invalid allocated port %u for remote "
1820                                     "forward to %s:%d", port,
1821                                     rfwd->connect_host, rfwd->connect_port);
1822                                 /* Ensure failure processing runs below */
1823                                 type = SSH2_MSG_REQUEST_FAILURE;
1824                                 channel_update_permission(ssh,
1825                                     rfwd->handle, -1);
1826                         } else {
1827                                 rfwd->allocated_port = (int)port;
1828                                 logit("Allocated port %u for remote "
1829                                     "forward to %s:%d",
1830                                     rfwd->allocated_port, rfwd->connect_path ?
1831                                     rfwd->connect_path : rfwd->connect_host,
1832                                     rfwd->connect_port);
1833                                 channel_update_permission(ssh,
1834                                     rfwd->handle, rfwd->allocated_port);
1835                         }
1836                 } else {
1837                         channel_update_permission(ssh, rfwd->handle, -1);
1838                 }
1839         }
1840
1841         if (type == SSH2_MSG_REQUEST_FAILURE) {
1842                 if (options.exit_on_forward_failure) {
1843                         if (rfwd->listen_path != NULL)
1844                                 fatal("Error: remote port forwarding failed "
1845                                     "for listen path %s", rfwd->listen_path);
1846                         else
1847                                 fatal("Error: remote port forwarding failed "
1848                                     "for listen port %d", rfwd->listen_port);
1849                 } else {
1850                         if (rfwd->listen_path != NULL)
1851                                 logit("Warning: remote port forwarding failed "
1852                                     "for listen path %s", rfwd->listen_path);
1853                         else
1854                                 logit("Warning: remote port forwarding failed "
1855                                     "for listen port %d", rfwd->listen_port);
1856                 }
1857         }
1858         forwarding_success();
1859 }
1860
1861 static void
1862 client_cleanup_stdio_fwd(struct ssh *ssh, int id, void *arg)
1863 {
1864         debug("stdio forwarding: done");
1865         cleanup_exit(0);
1866 }
1867
1868 static void
1869 ssh_stdio_confirm(struct ssh *ssh, int id, int success, void *arg)
1870 {
1871         if (!success)
1872                 fatal("stdio forwarding failed");
1873 }
1874
1875 static void
1876 ssh_tun_confirm(struct ssh *ssh, int id, int success, void *arg)
1877 {
1878         if (!success) {
1879                 error("Tunnel forwarding failed");
1880                 if (options.exit_on_forward_failure)
1881                         cleanup_exit(255);
1882         }
1883
1884         debug_f("tunnel forward established, id=%d", id);
1885         forwarding_success();
1886 }
1887
1888 static void
1889 ssh_init_stdio_forwarding(struct ssh *ssh)
1890 {
1891         Channel *c;
1892         int in, out;
1893
1894         if (options.stdio_forward_host == NULL)
1895                 return;
1896
1897         debug3_f("%s:%d", options.stdio_forward_host,
1898             options.stdio_forward_port);
1899
1900         if ((in = dup(STDIN_FILENO)) == -1 ||
1901             (out = dup(STDOUT_FILENO)) == -1)
1902                 fatal_f("dup() in/out failed");
1903         if ((c = channel_connect_stdio_fwd(ssh, options.stdio_forward_host,
1904             options.stdio_forward_port, in, out,
1905             CHANNEL_NONBLOCK_STDIO)) == NULL)
1906                 fatal_f("channel_connect_stdio_fwd failed");
1907         channel_register_cleanup(ssh, c->self, client_cleanup_stdio_fwd, 0);
1908         channel_register_open_confirm(ssh, c->self, ssh_stdio_confirm, NULL);
1909 }
1910
1911 static void
1912 ssh_init_forward_permissions(struct ssh *ssh, const char *what, char **opens,
1913     u_int num_opens)
1914 {
1915         u_int i;
1916         int port;
1917         char *addr, *arg, *oarg;
1918         int where = FORWARD_LOCAL;
1919
1920         channel_clear_permission(ssh, FORWARD_ADM, where);
1921         if (num_opens == 0)
1922                 return; /* permit any */
1923
1924         /* handle keywords: "any" / "none" */
1925         if (num_opens == 1 && strcmp(opens[0], "any") == 0)
1926                 return;
1927         if (num_opens == 1 && strcmp(opens[0], "none") == 0) {
1928                 channel_disable_admin(ssh, where);
1929                 return;
1930         }
1931         /* Otherwise treat it as a list of permitted host:port */
1932         for (i = 0; i < num_opens; i++) {
1933                 oarg = arg = xstrdup(opens[i]);
1934                 addr = hpdelim(&arg);
1935                 if (addr == NULL)
1936                         fatal_f("missing host in %s", what);
1937                 addr = cleanhostname(addr);
1938                 if (arg == NULL || ((port = permitopen_port(arg)) < 0))
1939                         fatal_f("bad port number in %s", what);
1940                 /* Send it to channels layer */
1941                 channel_add_permission(ssh, FORWARD_ADM,
1942                     where, addr, port);
1943                 free(oarg);
1944         }
1945 }
1946
1947 static void
1948 ssh_init_forwarding(struct ssh *ssh, char **ifname)
1949 {
1950         int success = 0;
1951         int i;
1952
1953         ssh_init_forward_permissions(ssh, "permitremoteopen",
1954             options.permitted_remote_opens,
1955             options.num_permitted_remote_opens);
1956
1957         if (options.exit_on_forward_failure)
1958                 forward_confirms_pending = 0; /* track pending requests */
1959         /* Initiate local TCP/IP port forwardings. */
1960         for (i = 0; i < options.num_local_forwards; i++) {
1961                 debug("Local connections to %.200s:%d forwarded to remote "
1962                     "address %.200s:%d",
1963                     (options.local_forwards[i].listen_path != NULL) ?
1964                     options.local_forwards[i].listen_path :
1965                     (options.local_forwards[i].listen_host == NULL) ?
1966                     (options.fwd_opts.gateway_ports ? "*" : "LOCALHOST") :
1967                     options.local_forwards[i].listen_host,
1968                     options.local_forwards[i].listen_port,
1969                     (options.local_forwards[i].connect_path != NULL) ?
1970                     options.local_forwards[i].connect_path :
1971                     options.local_forwards[i].connect_host,
1972                     options.local_forwards[i].connect_port);
1973                 success += channel_setup_local_fwd_listener(ssh,
1974                     &options.local_forwards[i], &options.fwd_opts);
1975         }
1976         if (i > 0 && success != i && options.exit_on_forward_failure)
1977                 fatal("Could not request local forwarding.");
1978         if (i > 0 && success == 0)
1979                 error("Could not request local forwarding.");
1980
1981         /* Initiate remote TCP/IP port forwardings. */
1982         for (i = 0; i < options.num_remote_forwards; i++) {
1983                 debug("Remote connections from %.200s:%d forwarded to "
1984                     "local address %.200s:%d",
1985                     (options.remote_forwards[i].listen_path != NULL) ?
1986                     options.remote_forwards[i].listen_path :
1987                     (options.remote_forwards[i].listen_host == NULL) ?
1988                     "LOCALHOST" : options.remote_forwards[i].listen_host,
1989                     options.remote_forwards[i].listen_port,
1990                     (options.remote_forwards[i].connect_path != NULL) ?
1991                     options.remote_forwards[i].connect_path :
1992                     options.remote_forwards[i].connect_host,
1993                     options.remote_forwards[i].connect_port);
1994                 if ((options.remote_forwards[i].handle =
1995                     channel_request_remote_forwarding(ssh,
1996                     &options.remote_forwards[i])) >= 0) {
1997                         client_register_global_confirm(
1998                             ssh_confirm_remote_forward,
1999                             &options.remote_forwards[i]);
2000                         forward_confirms_pending++;
2001                 } else if (options.exit_on_forward_failure)
2002                         fatal("Could not request remote forwarding.");
2003                 else
2004                         logit("Warning: Could not request remote forwarding.");
2005         }
2006
2007         /* Initiate tunnel forwarding. */
2008         if (options.tun_open != SSH_TUNMODE_NO) {
2009                 if ((*ifname = client_request_tun_fwd(ssh,
2010                     options.tun_open, options.tun_local,
2011                     options.tun_remote, ssh_tun_confirm, NULL)) != NULL)
2012                         forward_confirms_pending++;
2013                 else if (options.exit_on_forward_failure)
2014                         fatal("Could not request tunnel forwarding.");
2015                 else
2016                         error("Could not request tunnel forwarding.");
2017         }
2018         if (forward_confirms_pending > 0) {
2019                 debug_f("expecting replies for %d forwards",
2020                     forward_confirms_pending);
2021         }
2022 }
2023
2024 static void
2025 check_agent_present(void)
2026 {
2027         int r;
2028
2029         if (options.forward_agent) {
2030                 /* Clear agent forwarding if we don't have an agent. */
2031                 if ((r = ssh_get_authentication_socket(NULL)) != 0) {
2032                         options.forward_agent = 0;
2033                         if (r != SSH_ERR_AGENT_NOT_PRESENT)
2034                                 debug_r(r, "ssh_get_authentication_socket");
2035                 }
2036         }
2037 }
2038
2039 static void
2040 ssh_session2_setup(struct ssh *ssh, int id, int success, void *arg)
2041 {
2042         extern char **environ;
2043         const char *display, *term;
2044         int r, interactive = tty_flag;
2045         char *proto = NULL, *data = NULL;
2046
2047         if (!success)
2048                 return; /* No need for error message, channels code sens one */
2049
2050         display = getenv("DISPLAY");
2051         if (display == NULL && options.forward_x11)
2052                 debug("X11 forwarding requested but DISPLAY not set");
2053         if (options.forward_x11 && client_x11_get_proto(ssh, display,
2054             options.xauth_location, options.forward_x11_trusted,
2055             options.forward_x11_timeout, &proto, &data) == 0) {
2056                 /* Request forwarding with authentication spoofing. */
2057                 debug("Requesting X11 forwarding with authentication "
2058                     "spoofing.");
2059                 x11_request_forwarding_with_spoofing(ssh, id, display, proto,
2060                     data, 1);
2061                 client_expect_confirm(ssh, id, "X11 forwarding", CONFIRM_WARN);
2062                 /* XXX exit_on_forward_failure */
2063                 interactive = 1;
2064         }
2065
2066         check_agent_present();
2067         if (options.forward_agent) {
2068                 debug("Requesting authentication agent forwarding.");
2069                 channel_request_start(ssh, id, "auth-agent-req@openssh.com", 0);
2070                 if ((r = sshpkt_send(ssh)) != 0)
2071                         fatal_fr(r, "send packet");
2072         }
2073
2074         /* Tell the packet module whether this is an interactive session. */
2075         ssh_packet_set_interactive(ssh, interactive,
2076             options.ip_qos_interactive, options.ip_qos_bulk);
2077
2078         if ((term = lookup_env_in_list("TERM", options.setenv,
2079             options.num_setenv)) == NULL || *term == '\0')
2080                 term = getenv("TERM");
2081         client_session2_setup(ssh, id, tty_flag,
2082             options.session_type == SESSION_TYPE_SUBSYSTEM, term,
2083             NULL, fileno(stdin), command, environ);
2084 }
2085
2086 /* open new channel for a session */
2087 static int
2088 ssh_session2_open(struct ssh *ssh)
2089 {
2090         Channel *c;
2091         int window, packetmax, in, out, err;
2092
2093         if (options.stdin_null) {
2094                 in = open(_PATH_DEVNULL, O_RDONLY);
2095         } else {
2096                 in = dup(STDIN_FILENO);
2097         }
2098         out = dup(STDOUT_FILENO);
2099         err = dup(STDERR_FILENO);
2100
2101         if (in == -1 || out == -1 || err == -1)
2102                 fatal("dup() in/out/err failed");
2103
2104         window = CHAN_SES_WINDOW_DEFAULT;
2105         packetmax = CHAN_SES_PACKET_DEFAULT;
2106         if (tty_flag) {
2107                 window >>= 1;
2108                 packetmax >>= 1;
2109         }
2110         c = channel_new(ssh,
2111             "session", SSH_CHANNEL_OPENING, in, out, err,
2112             window, packetmax, CHAN_EXTENDED_WRITE,
2113             "client-session", CHANNEL_NONBLOCK_STDIO);
2114
2115         debug3_f("channel_new: %d", c->self);
2116
2117         channel_send_open(ssh, c->self);
2118         if (options.session_type != SESSION_TYPE_NONE)
2119                 channel_register_open_confirm(ssh, c->self,
2120                     ssh_session2_setup, NULL);
2121
2122         return c->self;
2123 }
2124
2125 static int
2126 ssh_session2(struct ssh *ssh, const struct ssh_conn_info *cinfo)
2127 {
2128         int r, id = -1;
2129         char *cp, *tun_fwd_ifname = NULL;
2130
2131         /* XXX should be pre-session */
2132         if (!options.control_persist)
2133                 ssh_init_stdio_forwarding(ssh);
2134
2135         ssh_init_forwarding(ssh, &tun_fwd_ifname);
2136
2137         if (options.local_command != NULL) {
2138                 debug3("expanding LocalCommand: %s", options.local_command);
2139                 cp = options.local_command;
2140                 options.local_command = percent_expand(cp,
2141                     DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(cinfo),
2142                     "T", tun_fwd_ifname == NULL ? "NONE" : tun_fwd_ifname,
2143                     (char *)NULL);
2144                 debug3("expanded LocalCommand: %s", options.local_command);
2145                 free(cp);
2146         }
2147
2148         /* Start listening for multiplex clients */
2149         if (!ssh_packet_get_mux(ssh))
2150                 muxserver_listen(ssh);
2151
2152         /*
2153          * If we are in control persist mode and have a working mux listen
2154          * socket, then prepare to background ourselves and have a foreground
2155          * client attach as a control client.
2156          * NB. we must save copies of the flags that we override for
2157          * the backgrounding, since we defer attachment of the client until
2158          * after the connection is fully established (in particular,
2159          * async rfwd replies have been received for ExitOnForwardFailure).
2160          */
2161         if (options.control_persist && muxserver_sock != -1) {
2162                 ostdin_null_flag = options.stdin_null;
2163                 osession_type = options.session_type;
2164                 orequest_tty = options.request_tty;
2165                 otty_flag = tty_flag;
2166                 options.stdin_null = 1;
2167                 options.session_type = SESSION_TYPE_NONE;
2168                 tty_flag = 0;
2169                 if (!options.fork_after_authentication &&
2170                     (osession_type != SESSION_TYPE_NONE ||
2171                     options.stdio_forward_host != NULL))
2172                         need_controlpersist_detach = 1;
2173                 options.fork_after_authentication = 1;
2174         }
2175         /*
2176          * ControlPersist mux listen socket setup failed, attempt the
2177          * stdio forward setup that we skipped earlier.
2178          */
2179         if (options.control_persist && muxserver_sock == -1)
2180                 ssh_init_stdio_forwarding(ssh);
2181
2182         if (options.session_type != SESSION_TYPE_NONE)
2183                 id = ssh_session2_open(ssh);
2184         else {
2185                 ssh_packet_set_interactive(ssh,
2186                     options.control_master == SSHCTL_MASTER_NO,
2187                     options.ip_qos_interactive, options.ip_qos_bulk);
2188         }
2189
2190         /* If we don't expect to open a new session, then disallow it */
2191         if (options.control_master == SSHCTL_MASTER_NO &&
2192             (ssh->compat & SSH_NEW_OPENSSH)) {
2193                 debug("Requesting no-more-sessions@openssh.com");
2194                 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2195                     (r = sshpkt_put_cstring(ssh,
2196                     "no-more-sessions@openssh.com")) != 0 ||
2197                     (r = sshpkt_put_u8(ssh, 0)) != 0 ||
2198                     (r = sshpkt_send(ssh)) != 0)
2199                         fatal_fr(r, "send packet");
2200         }
2201
2202         /* Execute a local command */
2203         if (options.local_command != NULL &&
2204             options.permit_local_command)
2205                 ssh_local_cmd(options.local_command);
2206
2207         /*
2208          * stdout is now owned by the session channel; clobber it here
2209          * so future channel closes are propagated to the local fd.
2210          * NB. this can only happen after LocalCommand has completed,
2211          * as it may want to write to stdout.
2212          */
2213         if (!need_controlpersist_detach && stdfd_devnull(0, 1, 0) == -1)
2214                 error_f("stdfd_devnull failed");
2215
2216         /*
2217          * If requested and we are not interested in replies to remote
2218          * forwarding requests, then let ssh continue in the background.
2219          */
2220         if (options.fork_after_authentication) {
2221                 if (options.exit_on_forward_failure &&
2222                     options.num_remote_forwards > 0) {
2223                         debug("deferring postauth fork until remote forward "
2224                             "confirmation received");
2225                 } else
2226                         fork_postauth();
2227         }
2228
2229         return client_loop(ssh, tty_flag, tty_flag ?
2230             options.escape_char : SSH_ESCAPECHAR_NONE, id);
2231 }
2232
2233 /* Loads all IdentityFile and CertificateFile keys */
2234 static void
2235 load_public_identity_files(const struct ssh_conn_info *cinfo)
2236 {
2237         char *filename, *cp;
2238         struct sshkey *public;
2239         int i;
2240         u_int n_ids, n_certs;
2241         char *identity_files[SSH_MAX_IDENTITY_FILES];
2242         struct sshkey *identity_keys[SSH_MAX_IDENTITY_FILES];
2243         int identity_file_userprovided[SSH_MAX_IDENTITY_FILES];
2244         char *certificate_files[SSH_MAX_CERTIFICATE_FILES];
2245         struct sshkey *certificates[SSH_MAX_CERTIFICATE_FILES];
2246         int certificate_file_userprovided[SSH_MAX_CERTIFICATE_FILES];
2247 #ifdef ENABLE_PKCS11
2248         struct sshkey **keys = NULL;
2249         char **comments = NULL;
2250         int nkeys;
2251 #endif /* PKCS11 */
2252
2253         n_ids = n_certs = 0;
2254         memset(identity_files, 0, sizeof(identity_files));
2255         memset(identity_keys, 0, sizeof(identity_keys));
2256         memset(identity_file_userprovided, 0,
2257             sizeof(identity_file_userprovided));
2258         memset(certificate_files, 0, sizeof(certificate_files));
2259         memset(certificates, 0, sizeof(certificates));
2260         memset(certificate_file_userprovided, 0,
2261             sizeof(certificate_file_userprovided));
2262
2263 #ifdef ENABLE_PKCS11
2264         if (options.pkcs11_provider != NULL &&
2265             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
2266             (pkcs11_init(!options.batch_mode) == 0) &&
2267             (nkeys = pkcs11_add_provider(options.pkcs11_provider, NULL,
2268             &keys, &comments)) > 0) {
2269                 for (i = 0; i < nkeys; i++) {
2270                         if (n_ids >= SSH_MAX_IDENTITY_FILES) {
2271                                 sshkey_free(keys[i]);
2272                                 free(comments[i]);
2273                                 continue;
2274                         }
2275                         identity_keys[n_ids] = keys[i];
2276                         identity_files[n_ids] = comments[i]; /* transferred */
2277                         n_ids++;
2278                 }
2279                 free(keys);
2280                 free(comments);
2281         }
2282 #endif /* ENABLE_PKCS11 */
2283         for (i = 0; i < options.num_identity_files; i++) {
2284                 if (n_ids >= SSH_MAX_IDENTITY_FILES ||
2285                     strcasecmp(options.identity_files[i], "none") == 0) {
2286                         free(options.identity_files[i]);
2287                         options.identity_files[i] = NULL;
2288                         continue;
2289                 }
2290                 cp = tilde_expand_filename(options.identity_files[i], getuid());
2291                 filename = default_client_percent_dollar_expand(cp, cinfo);
2292                 free(cp);
2293                 check_load(sshkey_load_public(filename, &public, NULL),
2294                     &public, filename, "pubkey");
2295                 debug("identity file %s type %d", filename,
2296                     public ? public->type : -1);
2297                 free(options.identity_files[i]);
2298                 identity_files[n_ids] = filename;
2299                 identity_keys[n_ids] = public;
2300                 identity_file_userprovided[n_ids] =
2301                     options.identity_file_userprovided[i];
2302                 if (++n_ids >= SSH_MAX_IDENTITY_FILES)
2303                         continue;
2304
2305                 /*
2306                  * If no certificates have been explicitly listed then try
2307                  * to add the default certificate variant too.
2308                  */
2309                 if (options.num_certificate_files != 0)
2310                         continue;
2311                 xasprintf(&cp, "%s-cert", filename);
2312                 check_load(sshkey_load_public(cp, &public, NULL),
2313                     &public, filename, "pubkey");
2314                 debug("identity file %s type %d", cp,
2315                     public ? public->type : -1);
2316                 if (public == NULL) {
2317                         free(cp);
2318                         continue;
2319                 }
2320                 if (!sshkey_is_cert(public)) {
2321                         debug_f("key %s type %s is not a certificate",
2322                             cp, sshkey_type(public));
2323                         sshkey_free(public);
2324                         free(cp);
2325                         continue;
2326                 }
2327                 /* NB. leave filename pointing to private key */
2328                 identity_files[n_ids] = xstrdup(filename);
2329                 identity_keys[n_ids] = public;
2330                 identity_file_userprovided[n_ids] =
2331                     options.identity_file_userprovided[i];
2332                 n_ids++;
2333         }
2334
2335         if (options.num_certificate_files > SSH_MAX_CERTIFICATE_FILES)
2336                 fatal_f("too many certificates");
2337         for (i = 0; i < options.num_certificate_files; i++) {
2338                 cp = tilde_expand_filename(options.certificate_files[i],
2339                     getuid());
2340                 filename = default_client_percent_dollar_expand(cp, cinfo);
2341                 free(cp);
2342
2343                 check_load(sshkey_load_public(filename, &public, NULL),
2344                     &public, filename, "certificate");
2345                 debug("certificate file %s type %d", filename,
2346                     public ? public->type : -1);
2347                 free(options.certificate_files[i]);
2348                 options.certificate_files[i] = NULL;
2349                 if (public == NULL) {
2350                         free(filename);
2351                         continue;
2352                 }
2353                 if (!sshkey_is_cert(public)) {
2354                         debug_f("key %s type %s is not a certificate",
2355                             filename, sshkey_type(public));
2356                         sshkey_free(public);
2357                         free(filename);
2358                         continue;
2359                 }
2360                 certificate_files[n_certs] = filename;
2361                 certificates[n_certs] = public;
2362                 certificate_file_userprovided[n_certs] =
2363                     options.certificate_file_userprovided[i];
2364                 ++n_certs;
2365         }
2366
2367         options.num_identity_files = n_ids;
2368         memcpy(options.identity_files, identity_files, sizeof(identity_files));
2369         memcpy(options.identity_keys, identity_keys, sizeof(identity_keys));
2370         memcpy(options.identity_file_userprovided,
2371             identity_file_userprovided, sizeof(identity_file_userprovided));
2372
2373         options.num_certificate_files = n_certs;
2374         memcpy(options.certificate_files,
2375             certificate_files, sizeof(certificate_files));
2376         memcpy(options.certificates, certificates, sizeof(certificates));
2377         memcpy(options.certificate_file_userprovided,
2378             certificate_file_userprovided,
2379             sizeof(certificate_file_userprovided));
2380 }
2381
2382 static void
2383 main_sigchld_handler(int sig)
2384 {
2385         int save_errno = errno;
2386         pid_t pid;
2387         int status;
2388
2389         while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
2390             (pid == -1 && errno == EINTR))
2391                 ;
2392         errno = save_errno;
2393 }