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1 /* $OpenBSD: sshd.c,v 1.485 2017/03/15 03:52:30 deraadt 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  * This program is the ssh daemon.  It listens for connections from clients,
7  * and performs authentication, executes use commands or shell, and forwards
8  * information to/from the application to the user client over an encrypted
9  * connection.  This can also handle forwarding of X11, TCP/IP, and
10  * authentication agent connections.
11  *
12  * As far as I am concerned, the code I have written for this software
13  * can be used freely for any purpose.  Any derived versions of this
14  * software must be clearly marked as such, and if the derived work is
15  * incompatible with the protocol description in the RFC file, it must be
16  * called by a name other than "ssh" or "Secure Shell".
17  *
18  * SSH2 implementation:
19  * Privilege Separation:
20  *
21  * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
22  * Copyright (c) 2002 Niels Provos.  All rights reserved.
23  *
24  * Redistribution and use in source and binary forms, with or without
25  * modification, are permitted provided that the following conditions
26  * are met:
27  * 1. Redistributions of source code must retain the above copyright
28  *    notice, this list of conditions and the following disclaimer.
29  * 2. Redistributions in binary form must reproduce the above copyright
30  *    notice, this list of conditions and the following disclaimer in the
31  *    documentation and/or other materials provided with the distribution.
32  *
33  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
43  */
44 
45 #include "includes.h"
46 
47 #include <sys/types.h>
48 #include <sys/ioctl.h>
49 #include <sys/socket.h>
50 #ifdef HAVE_SYS_STAT_H
51 # include <sys/stat.h>
52 #endif
53 #ifdef HAVE_SYS_TIME_H
54 # include <sys/time.h>
55 #endif
56 #include "openbsd-compat/sys-tree.h"
57 #include "openbsd-compat/sys-queue.h"
58 #include <sys/wait.h>
59 
60 #include <errno.h>
61 #include <fcntl.h>
62 #include <netdb.h>
63 #ifdef HAVE_PATHS_H
64 #include <paths.h>
65 #endif
66 #include <grp.h>
67 #include <pwd.h>
68 #include <signal.h>
69 #include <stdarg.h>
70 #include <stdio.h>
71 #include <stdlib.h>
72 #include <string.h>
73 #include <unistd.h>
74 #include <limits.h>
75 
76 #ifdef WITH_OPENSSL
77 #include <openssl/dh.h>
78 #include <openssl/bn.h>
79 #include <openssl/rand.h>
80 #include "openbsd-compat/openssl-compat.h"
81 #endif
82 
83 #ifdef HAVE_SECUREWARE
84 #include <sys/security.h>
85 #include <prot.h>
86 #endif
87 
88 #include "xmalloc.h"
89 #include "ssh.h"
90 #include "ssh2.h"
91 #include "rsa.h"
92 #include "sshpty.h"
93 #include "packet.h"
94 #include "log.h"
95 #include "buffer.h"
96 #include "misc.h"
97 #include "match.h"
98 #include "servconf.h"
99 #include "uidswap.h"
100 #include "compat.h"
101 #include "cipher.h"
102 #include "digest.h"
103 #include "key.h"
104 #include "kex.h"
105 #include "myproposal.h"
106 #include "authfile.h"
107 #include "pathnames.h"
108 #include "atomicio.h"
109 #include "canohost.h"
110 #include "hostfile.h"
111 #include "auth.h"
112 #include "authfd.h"
113 #include "msg.h"
114 #include "dispatch.h"
115 #include "channels.h"
116 #include "session.h"
117 #include "monitor.h"
118 #ifdef GSSAPI
119 #include "ssh-gss.h"
120 #endif
121 #include "monitor_wrap.h"
122 #include "ssh-sandbox.h"
123 #include "version.h"
124 #include "ssherr.h"
125 
126 /* Re-exec fds */
127 #define REEXEC_DEVCRYPTO_RESERVED_FD	(STDERR_FILENO + 1)
128 #define REEXEC_STARTUP_PIPE_FD		(STDERR_FILENO + 2)
129 #define REEXEC_CONFIG_PASS_FD		(STDERR_FILENO + 3)
130 #define REEXEC_MIN_FREE_FD		(STDERR_FILENO + 4)
131 
132 extern char *__progname;
133 
134 /* Server configuration options. */
135 ServerOptions options;
136 
137 /* Name of the server configuration file. */
138 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
139 
140 /*
141  * Debug mode flag.  This can be set on the command line.  If debug
142  * mode is enabled, extra debugging output will be sent to the system
143  * log, the daemon will not go to background, and will exit after processing
144  * the first connection.
145  */
146 int debug_flag = 0;
147 
148 /* Flag indicating that the daemon should only test the configuration and keys. */
149 int test_flag = 0;
150 
151 /* Flag indicating that the daemon is being started from inetd. */
152 int inetd_flag = 0;
153 
154 /* Flag indicating that sshd should not detach and become a daemon. */
155 int no_daemon_flag = 0;
156 
157 /* debug goes to stderr unless inetd_flag is set */
158 int log_stderr = 0;
159 
160 /* Saved arguments to main(). */
161 char **saved_argv;
162 int saved_argc;
163 
164 /* re-exec */
165 int rexeced_flag = 0;
166 int rexec_flag = 1;
167 int rexec_argc = 0;
168 char **rexec_argv;
169 
170 /*
171  * The sockets that the server is listening; this is used in the SIGHUP
172  * signal handler.
173  */
174 #define	MAX_LISTEN_SOCKS	16
175 int listen_socks[MAX_LISTEN_SOCKS];
176 int num_listen_socks = 0;
177 
178 /*
179  * the client's version string, passed by sshd2 in compat mode. if != NULL,
180  * sshd will skip the version-number exchange
181  */
182 char *client_version_string = NULL;
183 char *server_version_string = NULL;
184 
185 /* Daemon's agent connection */
186 int auth_sock = -1;
187 int have_agent = 0;
188 
189 /*
190  * Any really sensitive data in the application is contained in this
191  * structure. The idea is that this structure could be locked into memory so
192  * that the pages do not get written into swap.  However, there are some
193  * problems. The private key contains BIGNUMs, and we do not (in principle)
194  * have access to the internals of them, and locking just the structure is
195  * not very useful.  Currently, memory locking is not implemented.
196  */
197 struct {
198 	Key	**host_keys;		/* all private host keys */
199 	Key	**host_pubkeys;		/* all public host keys */
200 	Key	**host_certificates;	/* all public host certificates */
201 	int	have_ssh2_key;
202 } sensitive_data;
203 
204 /* This is set to true when a signal is received. */
205 static volatile sig_atomic_t received_sighup = 0;
206 static volatile sig_atomic_t received_sigterm = 0;
207 
208 /* session identifier, used by RSA-auth */
209 u_char session_id[16];
210 
211 /* same for ssh2 */
212 u_char *session_id2 = NULL;
213 u_int session_id2_len = 0;
214 
215 /* record remote hostname or ip */
216 u_int utmp_len = HOST_NAME_MAX+1;
217 
218 /* options.max_startup sized array of fd ints */
219 int *startup_pipes = NULL;
220 int startup_pipe;		/* in child */
221 
222 /* variables used for privilege separation */
223 int use_privsep = -1;
224 struct monitor *pmonitor = NULL;
225 int privsep_is_preauth = 1;
226 
227 /* global authentication context */
228 Authctxt *the_authctxt = NULL;
229 
230 /* sshd_config buffer */
231 Buffer cfg;
232 
233 /* message to be displayed after login */
234 Buffer loginmsg;
235 
236 /* Unprivileged user */
237 struct passwd *privsep_pw = NULL;
238 
239 /* Prototypes for various functions defined later in this file. */
240 void destroy_sensitive_data(void);
241 void demote_sensitive_data(void);
242 static void do_ssh2_kex(void);
243 
244 /*
245  * Close all listening sockets
246  */
247 static void
close_listen_socks(void)248 close_listen_socks(void)
249 {
250 	int i;
251 
252 	for (i = 0; i < num_listen_socks; i++)
253 		close(listen_socks[i]);
254 	num_listen_socks = -1;
255 }
256 
257 static void
close_startup_pipes(void)258 close_startup_pipes(void)
259 {
260 	int i;
261 
262 	if (startup_pipes)
263 		for (i = 0; i < options.max_startups; i++)
264 			if (startup_pipes[i] != -1)
265 				close(startup_pipes[i]);
266 }
267 
268 /*
269  * Signal handler for SIGHUP.  Sshd execs itself when it receives SIGHUP;
270  * the effect is to reread the configuration file (and to regenerate
271  * the server key).
272  */
273 
274 /*ARGSUSED*/
275 static void
sighup_handler(int sig)276 sighup_handler(int sig)
277 {
278 	int save_errno = errno;
279 
280 	received_sighup = 1;
281 	signal(SIGHUP, sighup_handler);
282 	errno = save_errno;
283 }
284 
285 /*
286  * Called from the main program after receiving SIGHUP.
287  * Restarts the server.
288  */
289 static void
sighup_restart(void)290 sighup_restart(void)
291 {
292 	logit("Received SIGHUP; restarting.");
293 	if (options.pid_file != NULL)
294 		unlink(options.pid_file);
295 	platform_pre_restart();
296 	close_listen_socks();
297 	close_startup_pipes();
298 	alarm(0);  /* alarm timer persists across exec */
299 	signal(SIGHUP, SIG_IGN); /* will be restored after exec */
300 	execv(saved_argv[0], saved_argv);
301 	logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
302 	    strerror(errno));
303 	exit(1);
304 }
305 
306 /*
307  * Generic signal handler for terminating signals in the master daemon.
308  */
309 /*ARGSUSED*/
310 static void
sigterm_handler(int sig)311 sigterm_handler(int sig)
312 {
313 	received_sigterm = sig;
314 }
315 
316 /*
317  * SIGCHLD handler.  This is called whenever a child dies.  This will then
318  * reap any zombies left by exited children.
319  */
320 /*ARGSUSED*/
321 static void
main_sigchld_handler(int sig)322 main_sigchld_handler(int sig)
323 {
324 	int save_errno = errno;
325 	pid_t pid;
326 	int status;
327 
328 	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
329 	    (pid < 0 && errno == EINTR))
330 		;
331 
332 	signal(SIGCHLD, main_sigchld_handler);
333 	errno = save_errno;
334 }
335 
336 /*
337  * Signal handler for the alarm after the login grace period has expired.
338  */
339 /*ARGSUSED*/
340 static void
grace_alarm_handler(int sig)341 grace_alarm_handler(int sig)
342 {
343 	if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
344 		kill(pmonitor->m_pid, SIGALRM);
345 
346 	/*
347 	 * Try to kill any processes that we have spawned, E.g. authorized
348 	 * keys command helpers.
349 	 */
350 	if (getpgid(0) == getpid()) {
351 		signal(SIGTERM, SIG_IGN);
352 		kill(0, SIGTERM);
353 	}
354 
355 	/* Log error and exit. */
356 	sigdie("Timeout before authentication for %s port %d",
357 	    ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
358 }
359 
360 static void
sshd_exchange_identification(struct ssh * ssh,int sock_in,int sock_out)361 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
362 {
363 	u_int i;
364 	int remote_major, remote_minor;
365 	char *s;
366 	char buf[256];			/* Must not be larger than remote_version. */
367 	char remote_version[256];	/* Must be at least as big as buf. */
368 
369 	xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
370 	    PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
371 	    *options.version_addendum == '\0' ? "" : " ",
372 	    options.version_addendum);
373 
374 	/* Send our protocol version identification. */
375 	if (atomicio(vwrite, sock_out, server_version_string,
376 	    strlen(server_version_string))
377 	    != strlen(server_version_string)) {
378 		logit("Could not write ident string to %s port %d",
379 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
380 		cleanup_exit(255);
381 	}
382 
383 	/* Read other sides version identification. */
384 	memset(buf, 0, sizeof(buf));
385 	for (i = 0; i < sizeof(buf) - 1; i++) {
386 		if (atomicio(read, sock_in, &buf[i], 1) != 1) {
387 			logit("Did not receive identification string "
388 			    "from %s port %d",
389 			    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
390 			cleanup_exit(255);
391 		}
392 		if (buf[i] == '\r') {
393 			buf[i] = 0;
394 			/* Kludge for F-Secure Macintosh < 1.0.2 */
395 			if (i == 12 &&
396 			    strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
397 				break;
398 			continue;
399 		}
400 		if (buf[i] == '\n') {
401 			buf[i] = 0;
402 			break;
403 		}
404 	}
405 	buf[sizeof(buf) - 1] = 0;
406 	client_version_string = xstrdup(buf);
407 
408 	/*
409 	 * Check that the versions match.  In future this might accept
410 	 * several versions and set appropriate flags to handle them.
411 	 */
412 	if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
413 	    &remote_major, &remote_minor, remote_version) != 3) {
414 		s = "Protocol mismatch.\n";
415 		(void) atomicio(vwrite, sock_out, s, strlen(s));
416 		logit("Bad protocol version identification '%.100s' "
417 		    "from %s port %d", client_version_string,
418 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
419 		close(sock_in);
420 		close(sock_out);
421 		cleanup_exit(255);
422 	}
423 	debug("Client protocol version %d.%d; client software version %.100s",
424 	    remote_major, remote_minor, remote_version);
425 
426 	ssh->compat = compat_datafellows(remote_version);
427 
428 	if ((ssh->compat & SSH_BUG_PROBE) != 0) {
429 		logit("probed from %s port %d with %s.  Don't panic.",
430 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
431 		    client_version_string);
432 		cleanup_exit(255);
433 	}
434 	if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
435 		logit("scanned from %s port %d with %s.  Don't panic.",
436 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
437 		    client_version_string);
438 		cleanup_exit(255);
439 	}
440 	if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
441 		logit("Client version \"%.100s\" uses unsafe RSA signature "
442 		    "scheme; disabling use of RSA keys", remote_version);
443 	}
444 	if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) {
445 		fatal("Client version \"%.100s\" uses unsafe key agreement; "
446 		    "refusing connection", remote_version);
447 	}
448 
449 	chop(server_version_string);
450 	debug("Local version string %.200s", server_version_string);
451 
452 	if (remote_major == 2 ||
453 	    (remote_major == 1 && remote_minor == 99)) {
454 		enable_compat20();
455 	} else {
456 		s = "Protocol major versions differ.\n";
457 		(void) atomicio(vwrite, sock_out, s, strlen(s));
458 		close(sock_in);
459 		close(sock_out);
460 		logit("Protocol major versions differ for %s port %d: "
461 		    "%.200s vs. %.200s",
462 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
463 		    server_version_string, client_version_string);
464 		cleanup_exit(255);
465 	}
466 }
467 
468 /* Destroy the host and server keys.  They will no longer be needed. */
469 void
destroy_sensitive_data(void)470 destroy_sensitive_data(void)
471 {
472 	int i;
473 
474 	for (i = 0; i < options.num_host_key_files; i++) {
475 		if (sensitive_data.host_keys[i]) {
476 			key_free(sensitive_data.host_keys[i]);
477 			sensitive_data.host_keys[i] = NULL;
478 		}
479 		if (sensitive_data.host_certificates[i]) {
480 			key_free(sensitive_data.host_certificates[i]);
481 			sensitive_data.host_certificates[i] = NULL;
482 		}
483 	}
484 }
485 
486 /* Demote private to public keys for network child */
487 void
demote_sensitive_data(void)488 demote_sensitive_data(void)
489 {
490 	Key *tmp;
491 	int i;
492 
493 	for (i = 0; i < options.num_host_key_files; i++) {
494 		if (sensitive_data.host_keys[i]) {
495 			tmp = key_demote(sensitive_data.host_keys[i]);
496 			key_free(sensitive_data.host_keys[i]);
497 			sensitive_data.host_keys[i] = tmp;
498 		}
499 		/* Certs do not need demotion */
500 	}
501 }
502 
503 static void
reseed_prngs(void)504 reseed_prngs(void)
505 {
506 	u_int32_t rnd[256];
507 
508 #ifdef WITH_OPENSSL
509 	RAND_poll();
510 #endif
511 	arc4random_stir(); /* noop on recent arc4random() implementations */
512 	arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
513 
514 #ifdef WITH_OPENSSL
515 	RAND_seed(rnd, sizeof(rnd));
516 	/* give libcrypto a chance to notice the PID change */
517 	if ((RAND_bytes((u_char *)rnd, 1)) != 1)
518 		fatal("%s: RAND_bytes failed", __func__);
519 #endif
520 
521 	explicit_bzero(rnd, sizeof(rnd));
522 }
523 
524 static void
privsep_preauth_child(void)525 privsep_preauth_child(void)
526 {
527 	gid_t gidset[1];
528 
529 	/* Enable challenge-response authentication for privilege separation */
530 	privsep_challenge_enable();
531 
532 #ifdef GSSAPI
533 	/* Cache supported mechanism OIDs for later use */
534 	if (options.gss_authentication)
535 		ssh_gssapi_prepare_supported_oids();
536 #endif
537 
538 	reseed_prngs();
539 
540 	/* Demote the private keys to public keys. */
541 	demote_sensitive_data();
542 
543 	/* Demote the child */
544 	if (getuid() == 0 || geteuid() == 0) {
545 		/* Change our root directory */
546 		if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
547 			fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
548 			    strerror(errno));
549 		if (chdir("/") == -1)
550 			fatal("chdir(\"/\"): %s", strerror(errno));
551 
552 		/* Drop our privileges */
553 		debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
554 		    (u_int)privsep_pw->pw_gid);
555 		gidset[0] = privsep_pw->pw_gid;
556 		if (setgroups(1, gidset) < 0)
557 			fatal("setgroups: %.100s", strerror(errno));
558 		permanently_set_uid(privsep_pw);
559 	}
560 }
561 
562 static int
privsep_preauth(Authctxt * authctxt)563 privsep_preauth(Authctxt *authctxt)
564 {
565 	int status, r;
566 	pid_t pid;
567 	struct ssh_sandbox *box = NULL;
568 
569 	/* Set up unprivileged child process to deal with network data */
570 	pmonitor = monitor_init();
571 	/* Store a pointer to the kex for later rekeying */
572 	pmonitor->m_pkex = &active_state->kex;
573 
574 	if (use_privsep == PRIVSEP_ON)
575 		box = ssh_sandbox_init(pmonitor);
576 	pid = fork();
577 	if (pid == -1) {
578 		fatal("fork of unprivileged child failed");
579 	} else if (pid != 0) {
580 		debug2("Network child is on pid %ld", (long)pid);
581 
582 		pmonitor->m_pid = pid;
583 		if (have_agent) {
584 			r = ssh_get_authentication_socket(&auth_sock);
585 			if (r != 0) {
586 				error("Could not get agent socket: %s",
587 				    ssh_err(r));
588 				have_agent = 0;
589 			}
590 		}
591 		if (box != NULL)
592 			ssh_sandbox_parent_preauth(box, pid);
593 		monitor_child_preauth(authctxt, pmonitor);
594 
595 		/* Wait for the child's exit status */
596 		while (waitpid(pid, &status, 0) < 0) {
597 			if (errno == EINTR)
598 				continue;
599 			pmonitor->m_pid = -1;
600 			fatal("%s: waitpid: %s", __func__, strerror(errno));
601 		}
602 		privsep_is_preauth = 0;
603 		pmonitor->m_pid = -1;
604 		if (WIFEXITED(status)) {
605 			if (WEXITSTATUS(status) != 0)
606 				fatal("%s: preauth child exited with status %d",
607 				    __func__, WEXITSTATUS(status));
608 		} else if (WIFSIGNALED(status))
609 			fatal("%s: preauth child terminated by signal %d",
610 			    __func__, WTERMSIG(status));
611 		if (box != NULL)
612 			ssh_sandbox_parent_finish(box);
613 		return 1;
614 	} else {
615 		/* child */
616 		close(pmonitor->m_sendfd);
617 		close(pmonitor->m_log_recvfd);
618 
619 		/* Arrange for logging to be sent to the monitor */
620 		set_log_handler(mm_log_handler, pmonitor);
621 
622 		privsep_preauth_child();
623 		setproctitle("%s", "[net]");
624 		if (box != NULL)
625 			ssh_sandbox_child(box);
626 
627 		return 0;
628 	}
629 }
630 
631 static void
privsep_postauth(Authctxt * authctxt)632 privsep_postauth(Authctxt *authctxt)
633 {
634 #ifdef DISABLE_FD_PASSING
635 	if (1) {
636 #else
637 	if (authctxt->pw->pw_uid == 0) {
638 #endif
639 		/* File descriptor passing is broken or root login */
640 		use_privsep = 0;
641 		goto skip;
642 	}
643 
644 	/* New socket pair */
645 	monitor_reinit(pmonitor);
646 
647 	pmonitor->m_pid = fork();
648 	if (pmonitor->m_pid == -1)
649 		fatal("fork of unprivileged child failed");
650 	else if (pmonitor->m_pid != 0) {
651 		verbose("User child is on pid %ld", (long)pmonitor->m_pid);
652 		buffer_clear(&loginmsg);
653 		monitor_child_postauth(pmonitor);
654 
655 		/* NEVERREACHED */
656 		exit(0);
657 	}
658 
659 	/* child */
660 
661 	close(pmonitor->m_sendfd);
662 	pmonitor->m_sendfd = -1;
663 
664 	/* Demote the private keys to public keys. */
665 	demote_sensitive_data();
666 
667 	reseed_prngs();
668 
669 	/* Drop privileges */
670 	do_setusercontext(authctxt->pw);
671 
672  skip:
673 	/* It is safe now to apply the key state */
674 	monitor_apply_keystate(pmonitor);
675 
676 	/*
677 	 * Tell the packet layer that authentication was successful, since
678 	 * this information is not part of the key state.
679 	 */
680 	packet_set_authenticated();
681 }
682 
683 static char *
684 list_hostkey_types(void)
685 {
686 	Buffer b;
687 	const char *p;
688 	char *ret;
689 	int i;
690 	Key *key;
691 
692 	buffer_init(&b);
693 	for (i = 0; i < options.num_host_key_files; i++) {
694 		key = sensitive_data.host_keys[i];
695 		if (key == NULL)
696 			key = sensitive_data.host_pubkeys[i];
697 		if (key == NULL)
698 			continue;
699 		/* Check that the key is accepted in HostkeyAlgorithms */
700 		if (match_pattern_list(sshkey_ssh_name(key),
701 		    options.hostkeyalgorithms, 0) != 1) {
702 			debug3("%s: %s key not permitted by HostkeyAlgorithms",
703 			    __func__, sshkey_ssh_name(key));
704 			continue;
705 		}
706 		switch (key->type) {
707 		case KEY_RSA:
708 		case KEY_DSA:
709 		case KEY_ECDSA:
710 		case KEY_ED25519:
711 			if (buffer_len(&b) > 0)
712 				buffer_append(&b, ",", 1);
713 			p = key_ssh_name(key);
714 			buffer_append(&b, p, strlen(p));
715 
716 			/* for RSA we also support SHA2 signatures */
717 			if (key->type == KEY_RSA) {
718 				p = ",rsa-sha2-512,rsa-sha2-256";
719 				buffer_append(&b, p, strlen(p));
720 			}
721 			break;
722 		}
723 		/* If the private key has a cert peer, then list that too */
724 		key = sensitive_data.host_certificates[i];
725 		if (key == NULL)
726 			continue;
727 		switch (key->type) {
728 		case KEY_RSA_CERT:
729 		case KEY_DSA_CERT:
730 		case KEY_ECDSA_CERT:
731 		case KEY_ED25519_CERT:
732 			if (buffer_len(&b) > 0)
733 				buffer_append(&b, ",", 1);
734 			p = key_ssh_name(key);
735 			buffer_append(&b, p, strlen(p));
736 			break;
737 		}
738 	}
739 	if ((ret = sshbuf_dup_string(&b)) == NULL)
740 		fatal("%s: sshbuf_dup_string failed", __func__);
741 	buffer_free(&b);
742 	debug("list_hostkey_types: %s", ret);
743 	return ret;
744 }
745 
746 static Key *
747 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
748 {
749 	int i;
750 	Key *key;
751 
752 	for (i = 0; i < options.num_host_key_files; i++) {
753 		switch (type) {
754 		case KEY_RSA_CERT:
755 		case KEY_DSA_CERT:
756 		case KEY_ECDSA_CERT:
757 		case KEY_ED25519_CERT:
758 			key = sensitive_data.host_certificates[i];
759 			break;
760 		default:
761 			key = sensitive_data.host_keys[i];
762 			if (key == NULL && !need_private)
763 				key = sensitive_data.host_pubkeys[i];
764 			break;
765 		}
766 		if (key != NULL && key->type == type &&
767 		    (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
768 			return need_private ?
769 			    sensitive_data.host_keys[i] : key;
770 	}
771 	return NULL;
772 }
773 
774 Key *
775 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
776 {
777 	return get_hostkey_by_type(type, nid, 0, ssh);
778 }
779 
780 Key *
781 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
782 {
783 	return get_hostkey_by_type(type, nid, 1, ssh);
784 }
785 
786 Key *
787 get_hostkey_by_index(int ind)
788 {
789 	if (ind < 0 || ind >= options.num_host_key_files)
790 		return (NULL);
791 	return (sensitive_data.host_keys[ind]);
792 }
793 
794 Key *
795 get_hostkey_public_by_index(int ind, struct ssh *ssh)
796 {
797 	if (ind < 0 || ind >= options.num_host_key_files)
798 		return (NULL);
799 	return (sensitive_data.host_pubkeys[ind]);
800 }
801 
802 int
803 get_hostkey_index(Key *key, int compare, struct ssh *ssh)
804 {
805 	int i;
806 
807 	for (i = 0; i < options.num_host_key_files; i++) {
808 		if (key_is_cert(key)) {
809 			if (key == sensitive_data.host_certificates[i] ||
810 			    (compare && sensitive_data.host_certificates[i] &&
811 			    sshkey_equal(key,
812 			    sensitive_data.host_certificates[i])))
813 				return (i);
814 		} else {
815 			if (key == sensitive_data.host_keys[i] ||
816 			    (compare && sensitive_data.host_keys[i] &&
817 			    sshkey_equal(key, sensitive_data.host_keys[i])))
818 				return (i);
819 			if (key == sensitive_data.host_pubkeys[i] ||
820 			    (compare && sensitive_data.host_pubkeys[i] &&
821 			    sshkey_equal(key, sensitive_data.host_pubkeys[i])))
822 				return (i);
823 		}
824 	}
825 	return (-1);
826 }
827 
828 /* Inform the client of all hostkeys */
829 static void
830 notify_hostkeys(struct ssh *ssh)
831 {
832 	struct sshbuf *buf;
833 	struct sshkey *key;
834 	int i, nkeys, r;
835 	char *fp;
836 
837 	/* Some clients cannot cope with the hostkeys message, skip those. */
838 	if (datafellows & SSH_BUG_HOSTKEYS)
839 		return;
840 
841 	if ((buf = sshbuf_new()) == NULL)
842 		fatal("%s: sshbuf_new", __func__);
843 	for (i = nkeys = 0; i < options.num_host_key_files; i++) {
844 		key = get_hostkey_public_by_index(i, ssh);
845 		if (key == NULL || key->type == KEY_UNSPEC ||
846 		    sshkey_is_cert(key))
847 			continue;
848 		fp = sshkey_fingerprint(key, options.fingerprint_hash,
849 		    SSH_FP_DEFAULT);
850 		debug3("%s: key %d: %s %s", __func__, i,
851 		    sshkey_ssh_name(key), fp);
852 		free(fp);
853 		if (nkeys == 0) {
854 			packet_start(SSH2_MSG_GLOBAL_REQUEST);
855 			packet_put_cstring("hostkeys-00@openssh.com");
856 			packet_put_char(0); /* want-reply */
857 		}
858 		sshbuf_reset(buf);
859 		if ((r = sshkey_putb(key, buf)) != 0)
860 			fatal("%s: couldn't put hostkey %d: %s",
861 			    __func__, i, ssh_err(r));
862 		packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
863 		nkeys++;
864 	}
865 	debug3("%s: sent %d hostkeys", __func__, nkeys);
866 	if (nkeys == 0)
867 		fatal("%s: no hostkeys", __func__);
868 	packet_send();
869 	sshbuf_free(buf);
870 }
871 
872 /*
873  * returns 1 if connection should be dropped, 0 otherwise.
874  * dropping starts at connection #max_startups_begin with a probability
875  * of (max_startups_rate/100). the probability increases linearly until
876  * all connections are dropped for startups > max_startups
877  */
878 static int
879 drop_connection(int startups)
880 {
881 	int p, r;
882 
883 	if (startups < options.max_startups_begin)
884 		return 0;
885 	if (startups >= options.max_startups)
886 		return 1;
887 	if (options.max_startups_rate == 100)
888 		return 1;
889 
890 	p  = 100 - options.max_startups_rate;
891 	p *= startups - options.max_startups_begin;
892 	p /= options.max_startups - options.max_startups_begin;
893 	p += options.max_startups_rate;
894 	r = arc4random_uniform(100);
895 
896 	debug("drop_connection: p %d, r %d", p, r);
897 	return (r < p) ? 1 : 0;
898 }
899 
900 static void
901 usage(void)
902 {
903 	fprintf(stderr, "%s, %s\n",
904 	    SSH_RELEASE,
905 #ifdef WITH_OPENSSL
906 	    SSLeay_version(SSLEAY_VERSION)
907 #else
908 	    "without OpenSSL"
909 #endif
910 	);
911 	fprintf(stderr,
912 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
913 "            [-E log_file] [-f config_file] [-g login_grace_time]\n"
914 "            [-h host_key_file] [-o option] [-p port] [-u len]\n"
915 	);
916 	exit(1);
917 }
918 
919 static void
920 send_rexec_state(int fd, struct sshbuf *conf)
921 {
922 	struct sshbuf *m;
923 	int r;
924 
925 	debug3("%s: entering fd = %d config len %zu", __func__, fd,
926 	    sshbuf_len(conf));
927 
928 	/*
929 	 * Protocol from reexec master to child:
930 	 *	string	configuration
931 	 *	string rngseed		(only if OpenSSL is not self-seeded)
932 	 */
933 	if ((m = sshbuf_new()) == NULL)
934 		fatal("%s: sshbuf_new failed", __func__);
935 	if ((r = sshbuf_put_stringb(m, conf)) != 0)
936 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
937 
938 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
939 	rexec_send_rng_seed(m);
940 #endif
941 
942 	if (ssh_msg_send(fd, 0, m) == -1)
943 		fatal("%s: ssh_msg_send failed", __func__);
944 
945 	sshbuf_free(m);
946 
947 	debug3("%s: done", __func__);
948 }
949 
950 static void
951 recv_rexec_state(int fd, Buffer *conf)
952 {
953 	Buffer m;
954 	char *cp;
955 	u_int len;
956 
957 	debug3("%s: entering fd = %d", __func__, fd);
958 
959 	buffer_init(&m);
960 
961 	if (ssh_msg_recv(fd, &m) == -1)
962 		fatal("%s: ssh_msg_recv failed", __func__);
963 	if (buffer_get_char(&m) != 0)
964 		fatal("%s: rexec version mismatch", __func__);
965 
966 	cp = buffer_get_string(&m, &len);
967 	if (conf != NULL)
968 		buffer_append(conf, cp, len);
969 	free(cp);
970 
971 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
972 	rexec_recv_rng_seed(&m);
973 #endif
974 
975 	buffer_free(&m);
976 
977 	debug3("%s: done", __func__);
978 }
979 
980 /* Accept a connection from inetd */
981 static void
982 server_accept_inetd(int *sock_in, int *sock_out)
983 {
984 	int fd;
985 
986 	startup_pipe = -1;
987 	if (rexeced_flag) {
988 		close(REEXEC_CONFIG_PASS_FD);
989 		*sock_in = *sock_out = dup(STDIN_FILENO);
990 		if (!debug_flag) {
991 			startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
992 			close(REEXEC_STARTUP_PIPE_FD);
993 		}
994 	} else {
995 		*sock_in = dup(STDIN_FILENO);
996 		*sock_out = dup(STDOUT_FILENO);
997 	}
998 	/*
999 	 * We intentionally do not close the descriptors 0, 1, and 2
1000 	 * as our code for setting the descriptors won't work if
1001 	 * ttyfd happens to be one of those.
1002 	 */
1003 	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1004 		dup2(fd, STDIN_FILENO);
1005 		dup2(fd, STDOUT_FILENO);
1006 		if (!log_stderr)
1007 			dup2(fd, STDERR_FILENO);
1008 		if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1009 			close(fd);
1010 	}
1011 	debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1012 }
1013 
1014 /*
1015  * Listen for TCP connections
1016  */
1017 static void
1018 server_listen(void)
1019 {
1020 	int ret, listen_sock, on = 1;
1021 	struct addrinfo *ai;
1022 	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1023 
1024 	for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1025 		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1026 			continue;
1027 		if (num_listen_socks >= MAX_LISTEN_SOCKS)
1028 			fatal("Too many listen sockets. "
1029 			    "Enlarge MAX_LISTEN_SOCKS");
1030 		if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1031 		    ntop, sizeof(ntop), strport, sizeof(strport),
1032 		    NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1033 			error("getnameinfo failed: %.100s",
1034 			    ssh_gai_strerror(ret));
1035 			continue;
1036 		}
1037 		/* Create socket for listening. */
1038 		listen_sock = socket(ai->ai_family, ai->ai_socktype,
1039 		    ai->ai_protocol);
1040 		if (listen_sock < 0) {
1041 			/* kernel may not support ipv6 */
1042 			verbose("socket: %.100s", strerror(errno));
1043 			continue;
1044 		}
1045 		if (set_nonblock(listen_sock) == -1) {
1046 			close(listen_sock);
1047 			continue;
1048 		}
1049 		if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1050 			verbose("socket: CLOEXEC: %s", strerror(errno));
1051 			close(listen_sock);
1052 			continue;
1053 		}
1054 		/*
1055 		 * Set socket options.
1056 		 * Allow local port reuse in TIME_WAIT.
1057 		 */
1058 		if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1059 		    &on, sizeof(on)) == -1)
1060 			error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1061 
1062 		/* Only communicate in IPv6 over AF_INET6 sockets. */
1063 		if (ai->ai_family == AF_INET6)
1064 			sock_set_v6only(listen_sock);
1065 
1066 		debug("Bind to port %s on %s.", strport, ntop);
1067 
1068 		/* Bind the socket to the desired port. */
1069 		if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1070 			error("Bind to port %s on %s failed: %.200s.",
1071 			    strport, ntop, strerror(errno));
1072 			close(listen_sock);
1073 			continue;
1074 		}
1075 		listen_socks[num_listen_socks] = listen_sock;
1076 		num_listen_socks++;
1077 
1078 		/* Start listening on the port. */
1079 		if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1080 			fatal("listen on [%s]:%s: %.100s",
1081 			    ntop, strport, strerror(errno));
1082 		logit("Server listening on %s port %s.", ntop, strport);
1083 	}
1084 	freeaddrinfo(options.listen_addrs);
1085 
1086 	if (!num_listen_socks)
1087 		fatal("Cannot bind any address.");
1088 }
1089 
1090 /*
1091  * The main TCP accept loop. Note that, for the non-debug case, returns
1092  * from this function are in a forked subprocess.
1093  */
1094 static void
1095 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1096 {
1097 	fd_set *fdset;
1098 	int i, j, ret, maxfd;
1099 	int startups = 0;
1100 	int startup_p[2] = { -1 , -1 };
1101 	struct sockaddr_storage from;
1102 	socklen_t fromlen;
1103 	pid_t pid;
1104 	u_char rnd[256];
1105 
1106 	/* setup fd set for accept */
1107 	fdset = NULL;
1108 	maxfd = 0;
1109 	for (i = 0; i < num_listen_socks; i++)
1110 		if (listen_socks[i] > maxfd)
1111 			maxfd = listen_socks[i];
1112 	/* pipes connected to unauthenticated childs */
1113 	startup_pipes = xcalloc(options.max_startups, sizeof(int));
1114 	for (i = 0; i < options.max_startups; i++)
1115 		startup_pipes[i] = -1;
1116 
1117 	/*
1118 	 * Stay listening for connections until the system crashes or
1119 	 * the daemon is killed with a signal.
1120 	 */
1121 	for (;;) {
1122 		if (received_sighup)
1123 			sighup_restart();
1124 		free(fdset);
1125 		fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1126 		    sizeof(fd_mask));
1127 
1128 		for (i = 0; i < num_listen_socks; i++)
1129 			FD_SET(listen_socks[i], fdset);
1130 		for (i = 0; i < options.max_startups; i++)
1131 			if (startup_pipes[i] != -1)
1132 				FD_SET(startup_pipes[i], fdset);
1133 
1134 		/* Wait in select until there is a connection. */
1135 		ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1136 		if (ret < 0 && errno != EINTR)
1137 			error("select: %.100s", strerror(errno));
1138 		if (received_sigterm) {
1139 			logit("Received signal %d; terminating.",
1140 			    (int) received_sigterm);
1141 			close_listen_socks();
1142 			if (options.pid_file != NULL)
1143 				unlink(options.pid_file);
1144 			exit(received_sigterm == SIGTERM ? 0 : 255);
1145 		}
1146 		if (ret < 0)
1147 			continue;
1148 
1149 		for (i = 0; i < options.max_startups; i++)
1150 			if (startup_pipes[i] != -1 &&
1151 			    FD_ISSET(startup_pipes[i], fdset)) {
1152 				/*
1153 				 * the read end of the pipe is ready
1154 				 * if the child has closed the pipe
1155 				 * after successful authentication
1156 				 * or if the child has died
1157 				 */
1158 				close(startup_pipes[i]);
1159 				startup_pipes[i] = -1;
1160 				startups--;
1161 			}
1162 		for (i = 0; i < num_listen_socks; i++) {
1163 			if (!FD_ISSET(listen_socks[i], fdset))
1164 				continue;
1165 			fromlen = sizeof(from);
1166 			*newsock = accept(listen_socks[i],
1167 			    (struct sockaddr *)&from, &fromlen);
1168 			if (*newsock < 0) {
1169 				if (errno != EINTR && errno != EWOULDBLOCK &&
1170 				    errno != ECONNABORTED && errno != EAGAIN)
1171 					error("accept: %.100s",
1172 					    strerror(errno));
1173 				if (errno == EMFILE || errno == ENFILE)
1174 					usleep(100 * 1000);
1175 				continue;
1176 			}
1177 			if (unset_nonblock(*newsock) == -1) {
1178 				close(*newsock);
1179 				continue;
1180 			}
1181 			if (drop_connection(startups) == 1) {
1182 				char *laddr = get_local_ipaddr(*newsock);
1183 				char *raddr = get_peer_ipaddr(*newsock);
1184 
1185 				verbose("drop connection #%d from [%s]:%d "
1186 				    "on [%s]:%d past MaxStartups", startups,
1187 				    raddr, get_peer_port(*newsock),
1188 				    laddr, get_local_port(*newsock));
1189 				free(laddr);
1190 				free(raddr);
1191 				close(*newsock);
1192 				continue;
1193 			}
1194 			if (pipe(startup_p) == -1) {
1195 				close(*newsock);
1196 				continue;
1197 			}
1198 
1199 			if (rexec_flag && socketpair(AF_UNIX,
1200 			    SOCK_STREAM, 0, config_s) == -1) {
1201 				error("reexec socketpair: %s",
1202 				    strerror(errno));
1203 				close(*newsock);
1204 				close(startup_p[0]);
1205 				close(startup_p[1]);
1206 				continue;
1207 			}
1208 
1209 			for (j = 0; j < options.max_startups; j++)
1210 				if (startup_pipes[j] == -1) {
1211 					startup_pipes[j] = startup_p[0];
1212 					if (maxfd < startup_p[0])
1213 						maxfd = startup_p[0];
1214 					startups++;
1215 					break;
1216 				}
1217 
1218 			/*
1219 			 * Got connection.  Fork a child to handle it, unless
1220 			 * we are in debugging mode.
1221 			 */
1222 			if (debug_flag) {
1223 				/*
1224 				 * In debugging mode.  Close the listening
1225 				 * socket, and start processing the
1226 				 * connection without forking.
1227 				 */
1228 				debug("Server will not fork when running in debugging mode.");
1229 				close_listen_socks();
1230 				*sock_in = *newsock;
1231 				*sock_out = *newsock;
1232 				close(startup_p[0]);
1233 				close(startup_p[1]);
1234 				startup_pipe = -1;
1235 				pid = getpid();
1236 				if (rexec_flag) {
1237 					send_rexec_state(config_s[0],
1238 					    &cfg);
1239 					close(config_s[0]);
1240 				}
1241 				break;
1242 			}
1243 
1244 			/*
1245 			 * Normal production daemon.  Fork, and have
1246 			 * the child process the connection. The
1247 			 * parent continues listening.
1248 			 */
1249 			platform_pre_fork();
1250 			if ((pid = fork()) == 0) {
1251 				/*
1252 				 * Child.  Close the listening and
1253 				 * max_startup sockets.  Start using
1254 				 * the accepted socket. Reinitialize
1255 				 * logging (since our pid has changed).
1256 				 * We break out of the loop to handle
1257 				 * the connection.
1258 				 */
1259 				platform_post_fork_child();
1260 				startup_pipe = startup_p[1];
1261 				close_startup_pipes();
1262 				close_listen_socks();
1263 				*sock_in = *newsock;
1264 				*sock_out = *newsock;
1265 				log_init(__progname,
1266 				    options.log_level,
1267 				    options.log_facility,
1268 				    log_stderr);
1269 				if (rexec_flag)
1270 					close(config_s[0]);
1271 				break;
1272 			}
1273 
1274 			/* Parent.  Stay in the loop. */
1275 			platform_post_fork_parent(pid);
1276 			if (pid < 0)
1277 				error("fork: %.100s", strerror(errno));
1278 			else
1279 				debug("Forked child %ld.", (long)pid);
1280 
1281 			close(startup_p[1]);
1282 
1283 			if (rexec_flag) {
1284 				send_rexec_state(config_s[0], &cfg);
1285 				close(config_s[0]);
1286 				close(config_s[1]);
1287 			}
1288 			close(*newsock);
1289 
1290 			/*
1291 			 * Ensure that our random state differs
1292 			 * from that of the child
1293 			 */
1294 			arc4random_stir();
1295 			arc4random_buf(rnd, sizeof(rnd));
1296 #ifdef WITH_OPENSSL
1297 			RAND_seed(rnd, sizeof(rnd));
1298 			if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1299 				fatal("%s: RAND_bytes failed", __func__);
1300 #endif
1301 			explicit_bzero(rnd, sizeof(rnd));
1302 		}
1303 
1304 		/* child process check (or debug mode) */
1305 		if (num_listen_socks < 0)
1306 			break;
1307 	}
1308 }
1309 
1310 /*
1311  * If IP options are supported, make sure there are none (log and
1312  * return an error if any are found).  Basically we are worried about
1313  * source routing; it can be used to pretend you are somebody
1314  * (ip-address) you are not. That itself may be "almost acceptable"
1315  * under certain circumstances, but rhosts autentication is useless
1316  * if source routing is accepted. Notice also that if we just dropped
1317  * source routing here, the other side could use IP spoofing to do
1318  * rest of the interaction and could still bypass security.  So we
1319  * exit here if we detect any IP options.
1320  */
1321 static void
1322 check_ip_options(struct ssh *ssh)
1323 {
1324 #ifdef IP_OPTIONS
1325 	int sock_in = ssh_packet_get_connection_in(ssh);
1326 	struct sockaddr_storage from;
1327 	u_char opts[200];
1328 	socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1329 	char text[sizeof(opts) * 3 + 1];
1330 
1331 	memset(&from, 0, sizeof(from));
1332 	if (getpeername(sock_in, (struct sockaddr *)&from,
1333 	    &fromlen) < 0)
1334 		return;
1335 	if (from.ss_family != AF_INET)
1336 		return;
1337 	/* XXX IPv6 options? */
1338 
1339 	if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1340 	    &option_size) >= 0 && option_size != 0) {
1341 		text[0] = '\0';
1342 		for (i = 0; i < option_size; i++)
1343 			snprintf(text + i*3, sizeof(text) - i*3,
1344 			    " %2.2x", opts[i]);
1345 		fatal("Connection from %.100s port %d with IP opts: %.800s",
1346 		    ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1347 	}
1348 	return;
1349 #endif /* IP_OPTIONS */
1350 }
1351 
1352 /*
1353  * Main program for the daemon.
1354  */
1355 int
1356 main(int ac, char **av)
1357 {
1358 	struct ssh *ssh = NULL;
1359 	extern char *optarg;
1360 	extern int optind;
1361 	int r, opt, i, j, on = 1, already_daemon;
1362 	int sock_in = -1, sock_out = -1, newsock = -1;
1363 	const char *remote_ip;
1364 	int remote_port;
1365 	char *fp, *line, *laddr, *logfile = NULL;
1366 	int config_s[2] = { -1 , -1 };
1367 	u_int n;
1368 	u_int64_t ibytes, obytes;
1369 	mode_t new_umask;
1370 	Key *key;
1371 	Key *pubkey;
1372 	int keytype;
1373 	Authctxt *authctxt;
1374 	struct connection_info *connection_info = get_connection_info(0, 0);
1375 
1376 	ssh_malloc_init();	/* must be called before any mallocs */
1377 
1378 #ifdef HAVE_SECUREWARE
1379 	(void)set_auth_parameters(ac, av);
1380 #endif
1381 	__progname = ssh_get_progname(av[0]);
1382 
1383 	/* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1384 	saved_argc = ac;
1385 	rexec_argc = ac;
1386 	saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1387 	for (i = 0; i < ac; i++)
1388 		saved_argv[i] = xstrdup(av[i]);
1389 	saved_argv[i] = NULL;
1390 
1391 #ifndef HAVE_SETPROCTITLE
1392 	/* Prepare for later setproctitle emulation */
1393 	compat_init_setproctitle(ac, av);
1394 	av = saved_argv;
1395 #endif
1396 
1397 	if (geteuid() == 0 && setgroups(0, NULL) == -1)
1398 		debug("setgroups(): %.200s", strerror(errno));
1399 
1400 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1401 	sanitise_stdfd();
1402 
1403 	/* Initialize configuration options to their default values. */
1404 	initialize_server_options(&options);
1405 
1406 	/* Parse command-line arguments. */
1407 	while ((opt = getopt(ac, av,
1408 	    "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1409 		switch (opt) {
1410 		case '4':
1411 			options.address_family = AF_INET;
1412 			break;
1413 		case '6':
1414 			options.address_family = AF_INET6;
1415 			break;
1416 		case 'f':
1417 			config_file_name = optarg;
1418 			break;
1419 		case 'c':
1420 			if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1421 				fprintf(stderr, "too many host certificates.\n");
1422 				exit(1);
1423 			}
1424 			options.host_cert_files[options.num_host_cert_files++] =
1425 			   derelativise_path(optarg);
1426 			break;
1427 		case 'd':
1428 			if (debug_flag == 0) {
1429 				debug_flag = 1;
1430 				options.log_level = SYSLOG_LEVEL_DEBUG1;
1431 			} else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1432 				options.log_level++;
1433 			break;
1434 		case 'D':
1435 			no_daemon_flag = 1;
1436 			break;
1437 		case 'E':
1438 			logfile = optarg;
1439 			/* FALLTHROUGH */
1440 		case 'e':
1441 			log_stderr = 1;
1442 			break;
1443 		case 'i':
1444 			inetd_flag = 1;
1445 			break;
1446 		case 'r':
1447 			rexec_flag = 0;
1448 			break;
1449 		case 'R':
1450 			rexeced_flag = 1;
1451 			inetd_flag = 1;
1452 			break;
1453 		case 'Q':
1454 			/* ignored */
1455 			break;
1456 		case 'q':
1457 			options.log_level = SYSLOG_LEVEL_QUIET;
1458 			break;
1459 		case 'b':
1460 			/* protocol 1, ignored */
1461 			break;
1462 		case 'p':
1463 			options.ports_from_cmdline = 1;
1464 			if (options.num_ports >= MAX_PORTS) {
1465 				fprintf(stderr, "too many ports.\n");
1466 				exit(1);
1467 			}
1468 			options.ports[options.num_ports++] = a2port(optarg);
1469 			if (options.ports[options.num_ports-1] <= 0) {
1470 				fprintf(stderr, "Bad port number.\n");
1471 				exit(1);
1472 			}
1473 			break;
1474 		case 'g':
1475 			if ((options.login_grace_time = convtime(optarg)) == -1) {
1476 				fprintf(stderr, "Invalid login grace time.\n");
1477 				exit(1);
1478 			}
1479 			break;
1480 		case 'k':
1481 			/* protocol 1, ignored */
1482 			break;
1483 		case 'h':
1484 			if (options.num_host_key_files >= MAX_HOSTKEYS) {
1485 				fprintf(stderr, "too many host keys.\n");
1486 				exit(1);
1487 			}
1488 			options.host_key_files[options.num_host_key_files++] =
1489 			   derelativise_path(optarg);
1490 			break;
1491 		case 't':
1492 			test_flag = 1;
1493 			break;
1494 		case 'T':
1495 			test_flag = 2;
1496 			break;
1497 		case 'C':
1498 			if (parse_server_match_testspec(connection_info,
1499 			    optarg) == -1)
1500 				exit(1);
1501 			break;
1502 		case 'u':
1503 			utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1504 			if (utmp_len > HOST_NAME_MAX+1) {
1505 				fprintf(stderr, "Invalid utmp length.\n");
1506 				exit(1);
1507 			}
1508 			break;
1509 		case 'o':
1510 			line = xstrdup(optarg);
1511 			if (process_server_config_line(&options, line,
1512 			    "command-line", 0, NULL, NULL) != 0)
1513 				exit(1);
1514 			free(line);
1515 			break;
1516 		case '?':
1517 		default:
1518 			usage();
1519 			break;
1520 		}
1521 	}
1522 	if (rexeced_flag || inetd_flag)
1523 		rexec_flag = 0;
1524 	if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1525 		fatal("sshd re-exec requires execution with an absolute path");
1526 	if (rexeced_flag)
1527 		closefrom(REEXEC_MIN_FREE_FD);
1528 	else
1529 		closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1530 
1531 #ifdef WITH_OPENSSL
1532 	OpenSSL_add_all_algorithms();
1533 #endif
1534 
1535 	/* If requested, redirect the logs to the specified logfile. */
1536 	if (logfile != NULL)
1537 		log_redirect_stderr_to(logfile);
1538 	/*
1539 	 * Force logging to stderr until we have loaded the private host
1540 	 * key (unless started from inetd)
1541 	 */
1542 	log_init(__progname,
1543 	    options.log_level == SYSLOG_LEVEL_NOT_SET ?
1544 	    SYSLOG_LEVEL_INFO : options.log_level,
1545 	    options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1546 	    SYSLOG_FACILITY_AUTH : options.log_facility,
1547 	    log_stderr || !inetd_flag);
1548 
1549 	/*
1550 	 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1551 	 * root's environment
1552 	 */
1553 	if (getenv("KRB5CCNAME") != NULL)
1554 		(void) unsetenv("KRB5CCNAME");
1555 
1556 #ifdef _UNICOS
1557 	/* Cray can define user privs drop all privs now!
1558 	 * Not needed on PRIV_SU systems!
1559 	 */
1560 	drop_cray_privs();
1561 #endif
1562 
1563 	sensitive_data.have_ssh2_key = 0;
1564 
1565 	/*
1566 	 * If we're doing an extended config test, make sure we have all of
1567 	 * the parameters we need.  If we're not doing an extended test,
1568 	 * do not silently ignore connection test params.
1569 	 */
1570 	if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1571 		fatal("user, host and addr are all required when testing "
1572 		   "Match configs");
1573 	if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1574 		fatal("Config test connection parameter (-C) provided without "
1575 		   "test mode (-T)");
1576 
1577 	/* Fetch our configuration */
1578 	buffer_init(&cfg);
1579 	if (rexeced_flag)
1580 		recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1581 	else if (strcasecmp(config_file_name, "none") != 0)
1582 		load_server_config(config_file_name, &cfg);
1583 
1584 	parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1585 	    &cfg, NULL);
1586 
1587 	seed_rng();
1588 
1589 	/* Fill in default values for those options not explicitly set. */
1590 	fill_default_server_options(&options);
1591 
1592 	/* challenge-response is implemented via keyboard interactive */
1593 	if (options.challenge_response_authentication)
1594 		options.kbd_interactive_authentication = 1;
1595 
1596 	/* Check that options are sensible */
1597 	if (options.authorized_keys_command_user == NULL &&
1598 	    (options.authorized_keys_command != NULL &&
1599 	    strcasecmp(options.authorized_keys_command, "none") != 0))
1600 		fatal("AuthorizedKeysCommand set without "
1601 		    "AuthorizedKeysCommandUser");
1602 	if (options.authorized_principals_command_user == NULL &&
1603 	    (options.authorized_principals_command != NULL &&
1604 	    strcasecmp(options.authorized_principals_command, "none") != 0))
1605 		fatal("AuthorizedPrincipalsCommand set without "
1606 		    "AuthorizedPrincipalsCommandUser");
1607 
1608 	/*
1609 	 * Check whether there is any path through configured auth methods.
1610 	 * Unfortunately it is not possible to verify this generally before
1611 	 * daemonisation in the presence of Match block, but this catches
1612 	 * and warns for trivial misconfigurations that could break login.
1613 	 */
1614 	if (options.num_auth_methods != 0) {
1615 		for (n = 0; n < options.num_auth_methods; n++) {
1616 			if (auth2_methods_valid(options.auth_methods[n],
1617 			    1) == 0)
1618 				break;
1619 		}
1620 		if (n >= options.num_auth_methods)
1621 			fatal("AuthenticationMethods cannot be satisfied by "
1622 			    "enabled authentication methods");
1623 	}
1624 
1625 	/* set default channel AF */
1626 	channel_set_af(options.address_family);
1627 
1628 	/* Check that there are no remaining arguments. */
1629 	if (optind < ac) {
1630 		fprintf(stderr, "Extra argument %s.\n", av[optind]);
1631 		exit(1);
1632 	}
1633 
1634 	debug("sshd version %s, %s", SSH_VERSION,
1635 #ifdef WITH_OPENSSL
1636 	    SSLeay_version(SSLEAY_VERSION)
1637 #else
1638 	    "without OpenSSL"
1639 #endif
1640 	);
1641 
1642 	/* Store privilege separation user for later use if required. */
1643 	if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1644 		if (use_privsep || options.kerberos_authentication)
1645 			fatal("Privilege separation user %s does not exist",
1646 			    SSH_PRIVSEP_USER);
1647 	} else {
1648 #if defined(ANDROID)
1649 /* Android does not do passwords and passes NULL for them. This breaks strlen */
1650           if (privsep_pw->pw_passwd) {
1651 #endif
1652 		explicit_bzero(privsep_pw->pw_passwd,
1653 		    strlen(privsep_pw->pw_passwd));
1654 		privsep_pw = pwcopy(privsep_pw);
1655 		free(privsep_pw->pw_passwd);
1656 #if defined(ANDROID)
1657           }
1658 #endif
1659 		privsep_pw->pw_passwd = xstrdup("*");
1660 	}
1661 #if !defined(ANDROID)
1662 	endpwent();
1663 #endif
1664 
1665 	/* load host keys */
1666 	sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1667 	    sizeof(Key *));
1668 	sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1669 	    sizeof(Key *));
1670 
1671 	if (options.host_key_agent) {
1672 		if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1673 			setenv(SSH_AUTHSOCKET_ENV_NAME,
1674 			    options.host_key_agent, 1);
1675 		if ((r = ssh_get_authentication_socket(NULL)) == 0)
1676 			have_agent = 1;
1677 		else
1678 			error("Could not connect to agent \"%s\": %s",
1679 			    options.host_key_agent, ssh_err(r));
1680 	}
1681 
1682 	for (i = 0; i < options.num_host_key_files; i++) {
1683 		if (options.host_key_files[i] == NULL)
1684 			continue;
1685 		key = key_load_private(options.host_key_files[i], "", NULL);
1686 		pubkey = key_load_public(options.host_key_files[i], NULL);
1687 
1688 		if ((pubkey != NULL && pubkey->type == KEY_RSA1) ||
1689 		    (key != NULL && key->type == KEY_RSA1)) {
1690 			verbose("Ignoring RSA1 key %s",
1691 			    options.host_key_files[i]);
1692 			key_free(key);
1693 			key_free(pubkey);
1694 			continue;
1695 		}
1696 		if (pubkey == NULL && key != NULL)
1697 			pubkey = key_demote(key);
1698 		sensitive_data.host_keys[i] = key;
1699 		sensitive_data.host_pubkeys[i] = pubkey;
1700 
1701 		if (key == NULL && pubkey != NULL && have_agent) {
1702 			debug("will rely on agent for hostkey %s",
1703 			    options.host_key_files[i]);
1704 			keytype = pubkey->type;
1705 		} else if (key != NULL) {
1706 			keytype = key->type;
1707 		} else {
1708 			error("Could not load host key: %s",
1709 			    options.host_key_files[i]);
1710 			sensitive_data.host_keys[i] = NULL;
1711 			sensitive_data.host_pubkeys[i] = NULL;
1712 			continue;
1713 		}
1714 
1715 		switch (keytype) {
1716 		case KEY_RSA:
1717 		case KEY_DSA:
1718 		case KEY_ECDSA:
1719 		case KEY_ED25519:
1720 			if (have_agent || key != NULL)
1721 				sensitive_data.have_ssh2_key = 1;
1722 			break;
1723 		}
1724 		if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1725 		    SSH_FP_DEFAULT)) == NULL)
1726 			fatal("sshkey_fingerprint failed");
1727 		debug("%s host key #%d: %s %s",
1728 		    key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1729 		free(fp);
1730 	}
1731 	if (!sensitive_data.have_ssh2_key) {
1732 		logit("sshd: no hostkeys available -- exiting.");
1733 		exit(1);
1734 	}
1735 
1736 	/*
1737 	 * Load certificates. They are stored in an array at identical
1738 	 * indices to the public keys that they relate to.
1739 	 */
1740 	sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1741 	    sizeof(Key *));
1742 	for (i = 0; i < options.num_host_key_files; i++)
1743 		sensitive_data.host_certificates[i] = NULL;
1744 
1745 	for (i = 0; i < options.num_host_cert_files; i++) {
1746 		if (options.host_cert_files[i] == NULL)
1747 			continue;
1748 		key = key_load_public(options.host_cert_files[i], NULL);
1749 		if (key == NULL) {
1750 			error("Could not load host certificate: %s",
1751 			    options.host_cert_files[i]);
1752 			continue;
1753 		}
1754 		if (!key_is_cert(key)) {
1755 			error("Certificate file is not a certificate: %s",
1756 			    options.host_cert_files[i]);
1757 			key_free(key);
1758 			continue;
1759 		}
1760 		/* Find matching private key */
1761 		for (j = 0; j < options.num_host_key_files; j++) {
1762 			if (key_equal_public(key,
1763 			    sensitive_data.host_keys[j])) {
1764 				sensitive_data.host_certificates[j] = key;
1765 				break;
1766 			}
1767 		}
1768 		if (j >= options.num_host_key_files) {
1769 			error("No matching private key for certificate: %s",
1770 			    options.host_cert_files[i]);
1771 			key_free(key);
1772 			continue;
1773 		}
1774 		sensitive_data.host_certificates[j] = key;
1775 		debug("host certificate: #%d type %d %s", j, key->type,
1776 		    key_type(key));
1777 	}
1778 
1779 	if (use_privsep) {
1780 		struct stat st;
1781 
1782 		if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1783 		    (S_ISDIR(st.st_mode) == 0))
1784 			fatal("Missing privilege separation directory: %s",
1785 			    _PATH_PRIVSEP_CHROOT_DIR);
1786 
1787 #ifdef HAVE_CYGWIN
1788 		if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1789 		    (st.st_uid != getuid () ||
1790 		    (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1791 #else
1792 		if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1793 #endif
1794 			fatal("%s must be owned by root and not group or "
1795 			    "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1796 	}
1797 
1798 	if (test_flag > 1) {
1799 		if (server_match_spec_complete(connection_info) == 1)
1800 			parse_server_match_config(&options, connection_info);
1801 		dump_config(&options);
1802 	}
1803 
1804 	/* Configuration looks good, so exit if in test mode. */
1805 	if (test_flag)
1806 		exit(0);
1807 
1808 	/*
1809 	 * Clear out any supplemental groups we may have inherited.  This
1810 	 * prevents inadvertent creation of files with bad modes (in the
1811 	 * portable version at least, it's certainly possible for PAM
1812 	 * to create a file, and we can't control the code in every
1813 	 * module which might be used).
1814 	 */
1815 	if (setgroups(0, NULL) < 0)
1816 		debug("setgroups() failed: %.200s", strerror(errno));
1817 
1818 	if (rexec_flag) {
1819 		rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1820 		for (i = 0; i < rexec_argc; i++) {
1821 			debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1822 			rexec_argv[i] = saved_argv[i];
1823 		}
1824 		rexec_argv[rexec_argc] = "-R";
1825 		rexec_argv[rexec_argc + 1] = NULL;
1826 	}
1827 
1828 	/* Ensure that umask disallows at least group and world write */
1829 	new_umask = umask(0077) | 0022;
1830 	(void) umask(new_umask);
1831 
1832 	/* Initialize the log (it is reinitialized below in case we forked). */
1833 	if (debug_flag && (!inetd_flag || rexeced_flag))
1834 		log_stderr = 1;
1835 	log_init(__progname, options.log_level, options.log_facility, log_stderr);
1836 
1837 	/*
1838 	 * If not in debugging mode, not started from inetd and not already
1839 	 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1840 	 * terminal, and fork.  The original process exits.
1841 	 */
1842 	already_daemon = daemonized();
1843 	if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1844 
1845 		if (daemon(0, 0) < 0)
1846 			fatal("daemon() failed: %.200s", strerror(errno));
1847 
1848 		disconnect_controlling_tty();
1849 	}
1850 	/* Reinitialize the log (because of the fork above). */
1851 	log_init(__progname, options.log_level, options.log_facility, log_stderr);
1852 
1853 	/* Chdir to the root directory so that the current disk can be
1854 	   unmounted if desired. */
1855 	if (chdir("/") == -1)
1856 		error("chdir(\"/\"): %s", strerror(errno));
1857 
1858 	/* ignore SIGPIPE */
1859 	signal(SIGPIPE, SIG_IGN);
1860 
1861 	/* Get a connection, either from inetd or a listening TCP socket */
1862 	if (inetd_flag) {
1863 		server_accept_inetd(&sock_in, &sock_out);
1864 	} else {
1865 		platform_pre_listen();
1866 		server_listen();
1867 
1868 		signal(SIGHUP, sighup_handler);
1869 		signal(SIGCHLD, main_sigchld_handler);
1870 		signal(SIGTERM, sigterm_handler);
1871 		signal(SIGQUIT, sigterm_handler);
1872 
1873 		/*
1874 		 * Write out the pid file after the sigterm handler
1875 		 * is setup and the listen sockets are bound
1876 		 */
1877 		if (options.pid_file != NULL && !debug_flag) {
1878 			FILE *f = fopen(options.pid_file, "w");
1879 
1880 			if (f == NULL) {
1881 				error("Couldn't create pid file \"%s\": %s",
1882 				    options.pid_file, strerror(errno));
1883 			} else {
1884 				fprintf(f, "%ld\n", (long) getpid());
1885 				fclose(f);
1886 			}
1887 		}
1888 
1889 		/* Accept a connection and return in a forked child */
1890 		server_accept_loop(&sock_in, &sock_out,
1891 		    &newsock, config_s);
1892 	}
1893 
1894 	/* This is the child processing a new connection. */
1895 	setproctitle("%s", "[accepted]");
1896 
1897 	/*
1898 	 * Create a new session and process group since the 4.4BSD
1899 	 * setlogin() affects the entire process group.  We don't
1900 	 * want the child to be able to affect the parent.
1901 	 */
1902 #if !defined(SSHD_ACQUIRES_CTTY)
1903 	/*
1904 	 * If setsid is called, on some platforms sshd will later acquire a
1905 	 * controlling terminal which will result in "could not set
1906 	 * controlling tty" errors.
1907 	 */
1908 	if (!debug_flag && !inetd_flag && setsid() < 0)
1909 		error("setsid: %.100s", strerror(errno));
1910 #endif
1911 
1912 	if (rexec_flag) {
1913 		int fd;
1914 
1915 		debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1916 		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1917 		dup2(newsock, STDIN_FILENO);
1918 		dup2(STDIN_FILENO, STDOUT_FILENO);
1919 		if (startup_pipe == -1)
1920 			close(REEXEC_STARTUP_PIPE_FD);
1921 		else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
1922 			dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1923 			close(startup_pipe);
1924 			startup_pipe = REEXEC_STARTUP_PIPE_FD;
1925 		}
1926 
1927 		dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1928 		close(config_s[1]);
1929 
1930 		execv(rexec_argv[0], rexec_argv);
1931 
1932 		/* Reexec has failed, fall back and continue */
1933 		error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1934 		recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1935 		log_init(__progname, options.log_level,
1936 		    options.log_facility, log_stderr);
1937 
1938 		/* Clean up fds */
1939 		close(REEXEC_CONFIG_PASS_FD);
1940 		newsock = sock_out = sock_in = dup(STDIN_FILENO);
1941 		if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1942 			dup2(fd, STDIN_FILENO);
1943 			dup2(fd, STDOUT_FILENO);
1944 			if (fd > STDERR_FILENO)
1945 				close(fd);
1946 		}
1947 		debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1948 		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1949 	}
1950 
1951 	/* Executed child processes don't need these. */
1952 	fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1953 	fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1954 
1955 	/*
1956 	 * Disable the key regeneration alarm.  We will not regenerate the
1957 	 * key since we are no longer in a position to give it to anyone. We
1958 	 * will not restart on SIGHUP since it no longer makes sense.
1959 	 */
1960 	alarm(0);
1961 	signal(SIGALRM, SIG_DFL);
1962 	signal(SIGHUP, SIG_DFL);
1963 	signal(SIGTERM, SIG_DFL);
1964 	signal(SIGQUIT, SIG_DFL);
1965 	signal(SIGCHLD, SIG_DFL);
1966 	signal(SIGINT, SIG_DFL);
1967 
1968 	/*
1969 	 * Register our connection.  This turns encryption off because we do
1970 	 * not have a key.
1971 	 */
1972 	packet_set_connection(sock_in, sock_out);
1973 	packet_set_server();
1974 	ssh = active_state; /* XXX */
1975 	check_ip_options(ssh);
1976 
1977 	/* Set SO_KEEPALIVE if requested. */
1978 	if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1979 	    setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1980 		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1981 
1982 	if ((remote_port = ssh_remote_port(ssh)) < 0) {
1983 		debug("ssh_remote_port failed");
1984 		cleanup_exit(255);
1985 	}
1986 
1987 	/*
1988 	 * The rest of the code depends on the fact that
1989 	 * ssh_remote_ipaddr() caches the remote ip, even if
1990 	 * the socket goes away.
1991 	 */
1992 	remote_ip = ssh_remote_ipaddr(ssh);
1993 
1994 #ifdef SSH_AUDIT_EVENTS
1995 	audit_connection_from(remote_ip, remote_port);
1996 #endif
1997 
1998 	/* Log the connection. */
1999 	laddr = get_local_ipaddr(sock_in);
2000 	verbose("Connection from %s port %d on %s port %d",
2001 	    remote_ip, remote_port, laddr,  ssh_local_port(ssh));
2002 	free(laddr);
2003 
2004 	/*
2005 	 * We don't want to listen forever unless the other side
2006 	 * successfully authenticates itself.  So we set up an alarm which is
2007 	 * cleared after successful authentication.  A limit of zero
2008 	 * indicates no limit. Note that we don't set the alarm in debugging
2009 	 * mode; it is just annoying to have the server exit just when you
2010 	 * are about to discover the bug.
2011 	 */
2012 	signal(SIGALRM, grace_alarm_handler);
2013 	if (!debug_flag)
2014 		alarm(options.login_grace_time);
2015 
2016 	sshd_exchange_identification(ssh, sock_in, sock_out);
2017 	packet_set_nonblocking();
2018 
2019 	/* allocate authentication context */
2020 	authctxt = xcalloc(1, sizeof(*authctxt));
2021 
2022 	authctxt->loginmsg = &loginmsg;
2023 
2024 	/* XXX global for cleanup, access from other modules */
2025 	the_authctxt = authctxt;
2026 
2027 	/* prepare buffer to collect messages to display to user after login */
2028 	buffer_init(&loginmsg);
2029 	auth_debug_reset();
2030 
2031 	if (use_privsep) {
2032 		if (privsep_preauth(authctxt) == 1)
2033 			goto authenticated;
2034 	} else if (have_agent) {
2035 		if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2036 			error("Unable to get agent socket: %s", ssh_err(r));
2037 			have_agent = 0;
2038 		}
2039 	}
2040 
2041 	/* perform the key exchange */
2042 	/* authenticate user and start session */
2043 	do_ssh2_kex();
2044 	do_authentication2(authctxt);
2045 
2046 	/*
2047 	 * If we use privilege separation, the unprivileged child transfers
2048 	 * the current keystate and exits
2049 	 */
2050 	if (use_privsep) {
2051 		mm_send_keystate(pmonitor);
2052 		exit(0);
2053 	}
2054 
2055  authenticated:
2056 	/*
2057 	 * Cancel the alarm we set to limit the time taken for
2058 	 * authentication.
2059 	 */
2060 	alarm(0);
2061 	signal(SIGALRM, SIG_DFL);
2062 	authctxt->authenticated = 1;
2063 	if (startup_pipe != -1) {
2064 		close(startup_pipe);
2065 		startup_pipe = -1;
2066 	}
2067 
2068 #ifdef SSH_AUDIT_EVENTS
2069 	audit_event(SSH_AUTH_SUCCESS);
2070 #endif
2071 
2072 #ifdef GSSAPI
2073 	if (options.gss_authentication) {
2074 		temporarily_use_uid(authctxt->pw);
2075 		ssh_gssapi_storecreds();
2076 		restore_uid();
2077 	}
2078 #endif
2079 #ifdef USE_PAM
2080 	if (options.use_pam) {
2081 		do_pam_setcred(1);
2082 		do_pam_session();
2083 	}
2084 #endif
2085 
2086 	/*
2087 	 * In privilege separation, we fork another child and prepare
2088 	 * file descriptor passing.
2089 	 */
2090 	if (use_privsep) {
2091 		privsep_postauth(authctxt);
2092 		/* the monitor process [priv] will not return */
2093 	}
2094 
2095 	packet_set_timeout(options.client_alive_interval,
2096 	    options.client_alive_count_max);
2097 
2098 	/* Try to send all our hostkeys to the client */
2099 	notify_hostkeys(active_state);
2100 
2101 	/* Start session. */
2102 	do_authenticated(authctxt);
2103 
2104 	/* The connection has been terminated. */
2105 	packet_get_bytes(&ibytes, &obytes);
2106 	verbose("Transferred: sent %llu, received %llu bytes",
2107 	    (unsigned long long)obytes, (unsigned long long)ibytes);
2108 
2109 	verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2110 
2111 #ifdef USE_PAM
2112 	if (options.use_pam)
2113 		finish_pam();
2114 #endif /* USE_PAM */
2115 
2116 #ifdef SSH_AUDIT_EVENTS
2117 	PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2118 #endif
2119 
2120 	packet_close();
2121 
2122 	if (use_privsep)
2123 		mm_terminate();
2124 
2125 	exit(0);
2126 }
2127 
2128 int
2129 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen,
2130     const u_char *data, size_t dlen, const char *alg, u_int flag)
2131 {
2132 	int r;
2133 	u_int xxx_slen, xxx_dlen = dlen;
2134 
2135 	if (privkey) {
2136 		if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen,
2137 		    alg) < 0))
2138 			fatal("%s: key_sign failed", __func__);
2139 		if (slen)
2140 			*slen = xxx_slen;
2141 	} else if (use_privsep) {
2142 		if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen,
2143 		    alg) < 0)
2144 			fatal("%s: pubkey_sign failed", __func__);
2145 		if (slen)
2146 			*slen = xxx_slen;
2147 	} else {
2148 		if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen,
2149 		    data, dlen, alg, datafellows)) != 0)
2150 			fatal("%s: ssh_agent_sign failed: %s",
2151 			    __func__, ssh_err(r));
2152 	}
2153 	return 0;
2154 }
2155 
2156 /* SSH2 key exchange */
2157 static void
2158 do_ssh2_kex(void)
2159 {
2160 	char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2161 	struct kex *kex;
2162 	int r;
2163 
2164 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2165 	    options.kex_algorithms);
2166 	myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2167 	    options.ciphers);
2168 	myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2169 	    options.ciphers);
2170 	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2171 	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2172 
2173 	if (options.compression == COMP_NONE) {
2174 		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2175 		    myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2176 	}
2177 
2178 	if (options.rekey_limit || options.rekey_interval)
2179 		packet_set_rekey_limits(options.rekey_limit,
2180 		    options.rekey_interval);
2181 
2182 	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2183 	    list_hostkey_types());
2184 
2185 	/* start key exchange */
2186 	if ((r = kex_setup(active_state, myproposal)) != 0)
2187 		fatal("kex_setup: %s", ssh_err(r));
2188 	kex = active_state->kex;
2189 #ifdef WITH_OPENSSL
2190 	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2191 	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2192 	kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2193 	kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2194 	kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2195 	kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2196 	kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2197 # ifdef OPENSSL_HAS_ECC
2198 	kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2199 # endif
2200 #endif
2201 	kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2202 	kex->server = 1;
2203 	kex->client_version_string=client_version_string;
2204 	kex->server_version_string=server_version_string;
2205 	kex->load_host_public_key=&get_hostkey_public_by_type;
2206 	kex->load_host_private_key=&get_hostkey_private_by_type;
2207 	kex->host_key_index=&get_hostkey_index;
2208 	kex->sign = sshd_hostkey_sign;
2209 
2210 	dispatch_run(DISPATCH_BLOCK, &kex->done, active_state);
2211 
2212 	session_id2 = kex->session_id;
2213 	session_id2_len = kex->session_id_len;
2214 
2215 #ifdef DEBUG_KEXDH
2216 	/* send 1st encrypted/maced/compressed message */
2217 	packet_start(SSH2_MSG_IGNORE);
2218 	packet_put_cstring("markus");
2219 	packet_send();
2220 	packet_write_wait();
2221 #endif
2222 	debug("KEX done");
2223 }
2224 
2225 /* server specific fatal cleanup */
2226 void
2227 cleanup_exit(int i)
2228 {
2229 	if (the_authctxt) {
2230 		do_cleanup(the_authctxt);
2231 		if (use_privsep && privsep_is_preauth &&
2232 		    pmonitor != NULL && pmonitor->m_pid > 1) {
2233 			debug("Killing privsep child %d", pmonitor->m_pid);
2234 			if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2235 			    errno != ESRCH)
2236 				error("%s: kill(%d): %s", __func__,
2237 				    pmonitor->m_pid, strerror(errno));
2238 		}
2239 	}
2240 #ifdef SSH_AUDIT_EVENTS
2241 	/* done after do_cleanup so it can cancel the PAM auth 'thread' */
2242 	if (!use_privsep || mm_is_monitor())
2243 		audit_event(SSH_CONNECTION_ABANDON);
2244 #endif
2245 	_exit(i);
2246 }
2247