sshd.c revision 262566
1/* $OpenBSD: sshd.c,v 1.414 2014/01/09 23:26:48 djm Exp $ */
2/* $FreeBSD: stable/10/crypto/openssh/sshd.c 262566 2014-02-27 17:29:02Z des $ */
3/*
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 *                    All rights reserved
7 * This program is the ssh daemon.  It listens for connections from clients,
8 * and performs authentication, executes use commands or shell, and forwards
9 * information to/from the application to the user client over an encrypted
10 * connection.  This can also handle forwarding of X11, TCP/IP, and
11 * authentication agent connections.
12 *
13 * As far as I am concerned, the code I have written for this software
14 * can be used freely for any purpose.  Any derived versions of this
15 * software must be clearly marked as such, and if the derived work is
16 * incompatible with the protocol description in the RFC file, it must be
17 * called by a name other than "ssh" or "Secure Shell".
18 *
19 * SSH2 implementation:
20 * Privilege Separation:
21 *
22 * Copyright (c) 2000, 2001, 2002 Markus Friedl.  All rights reserved.
23 * Copyright (c) 2002 Niels Provos.  All rights reserved.
24 *
25 * Redistribution and use in source and binary forms, with or without
26 * modification, are permitted provided that the following conditions
27 * are met:
28 * 1. Redistributions of source code must retain the above copyright
29 *    notice, this list of conditions and the following disclaimer.
30 * 2. Redistributions in binary form must reproduce the above copyright
31 *    notice, this list of conditions and the following disclaimer in the
32 *    documentation and/or other materials provided with the distribution.
33 *
34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
44 */
45
46#include "includes.h"
47__RCSID("$FreeBSD: stable/10/crypto/openssh/sshd.c 262566 2014-02-27 17:29:02Z des $");
48
49#include <sys/types.h>
50#include <sys/ioctl.h>
51#include <sys/mman.h>
52#include <sys/socket.h>
53#ifdef HAVE_SYS_STAT_H
54# include <sys/stat.h>
55#endif
56#ifdef HAVE_SYS_TIME_H
57# include <sys/time.h>
58#endif
59#include "openbsd-compat/sys-tree.h"
60#include "openbsd-compat/sys-queue.h"
61#include <sys/wait.h>
62
63#include <errno.h>
64#include <fcntl.h>
65#include <netdb.h>
66#ifdef HAVE_PATHS_H
67#include <paths.h>
68#endif
69#include <grp.h>
70#include <pwd.h>
71#include <signal.h>
72#include <stdarg.h>
73#include <stdio.h>
74#include <stdlib.h>
75#include <string.h>
76#include <unistd.h>
77
78#include <openssl/dh.h>
79#include <openssl/bn.h>
80#include <openssl/md5.h>
81#include <openssl/rand.h>
82#include "openbsd-compat/openssl-compat.h"
83
84#ifdef HAVE_SECUREWARE
85#include <sys/security.h>
86#include <prot.h>
87#endif
88
89#ifdef __FreeBSD__
90#include <resolv.h>
91#if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
92#include <gssapi/gssapi.h>
93#elif defined(GSSAPI) && defined(HAVE_GSSAPI_H)
94#include <gssapi.h>
95#endif
96#endif
97
98#include "xmalloc.h"
99#include "ssh.h"
100#include "ssh1.h"
101#include "ssh2.h"
102#include "rsa.h"
103#include "sshpty.h"
104#include "packet.h"
105#include "log.h"
106#include "buffer.h"
107#include "servconf.h"
108#include "uidswap.h"
109#include "compat.h"
110#include "cipher.h"
111#include "key.h"
112#include "kex.h"
113#include "dh.h"
114#include "myproposal.h"
115#include "authfile.h"
116#include "pathnames.h"
117#include "atomicio.h"
118#include "canohost.h"
119#include "hostfile.h"
120#include "auth.h"
121#include "authfd.h"
122#include "misc.h"
123#include "msg.h"
124#include "dispatch.h"
125#include "channels.h"
126#include "session.h"
127#include "monitor_mm.h"
128#include "monitor.h"
129#ifdef GSSAPI
130#include "ssh-gss.h"
131#endif
132#include "monitor_wrap.h"
133#include "roaming.h"
134#include "ssh-sandbox.h"
135#include "version.h"
136
137#ifdef LIBWRAP
138#include <tcpd.h>
139#include <syslog.h>
140int allow_severity;
141int deny_severity;
142#endif /* LIBWRAP */
143
144#ifndef O_NOCTTY
145#define O_NOCTTY	0
146#endif
147
148/* Re-exec fds */
149#define REEXEC_DEVCRYPTO_RESERVED_FD	(STDERR_FILENO + 1)
150#define REEXEC_STARTUP_PIPE_FD		(STDERR_FILENO + 2)
151#define REEXEC_CONFIG_PASS_FD		(STDERR_FILENO + 3)
152#define REEXEC_MIN_FREE_FD		(STDERR_FILENO + 4)
153
154extern char *__progname;
155
156/* Server configuration options. */
157ServerOptions options;
158
159/* Name of the server configuration file. */
160char *config_file_name = _PATH_SERVER_CONFIG_FILE;
161
162/*
163 * Debug mode flag.  This can be set on the command line.  If debug
164 * mode is enabled, extra debugging output will be sent to the system
165 * log, the daemon will not go to background, and will exit after processing
166 * the first connection.
167 */
168int debug_flag = 0;
169
170/* Flag indicating that the daemon should only test the configuration and keys. */
171int test_flag = 0;
172
173/* Flag indicating that the daemon is being started from inetd. */
174int inetd_flag = 0;
175
176/* Flag indicating that sshd should not detach and become a daemon. */
177int no_daemon_flag = 0;
178
179/* debug goes to stderr unless inetd_flag is set */
180int log_stderr = 0;
181
182/* Saved arguments to main(). */
183char **saved_argv;
184int saved_argc;
185
186/* re-exec */
187int rexeced_flag = 0;
188int rexec_flag = 1;
189int rexec_argc = 0;
190char **rexec_argv;
191
192/*
193 * The sockets that the server is listening; this is used in the SIGHUP
194 * signal handler.
195 */
196#define	MAX_LISTEN_SOCKS	16
197int listen_socks[MAX_LISTEN_SOCKS];
198int num_listen_socks = 0;
199
200/*
201 * the client's version string, passed by sshd2 in compat mode. if != NULL,
202 * sshd will skip the version-number exchange
203 */
204char *client_version_string = NULL;
205char *server_version_string = NULL;
206
207/* for rekeying XXX fixme */
208Kex *xxx_kex;
209
210/* Daemon's agent connection */
211AuthenticationConnection *auth_conn = NULL;
212int have_agent = 0;
213
214/*
215 * Any really sensitive data in the application is contained in this
216 * structure. The idea is that this structure could be locked into memory so
217 * that the pages do not get written into swap.  However, there are some
218 * problems. The private key contains BIGNUMs, and we do not (in principle)
219 * have access to the internals of them, and locking just the structure is
220 * not very useful.  Currently, memory locking is not implemented.
221 */
222struct {
223	Key	*server_key;		/* ephemeral server key */
224	Key	*ssh1_host_key;		/* ssh1 host key */
225	Key	**host_keys;		/* all private host keys */
226	Key	**host_pubkeys;		/* all public host keys */
227	Key	**host_certificates;	/* all public host certificates */
228	int	have_ssh1_key;
229	int	have_ssh2_key;
230	u_char	ssh1_cookie[SSH_SESSION_KEY_LENGTH];
231} sensitive_data;
232
233/*
234 * Flag indicating whether the RSA server key needs to be regenerated.
235 * Is set in the SIGALRM handler and cleared when the key is regenerated.
236 */
237static volatile sig_atomic_t key_do_regen = 0;
238
239/* This is set to true when a signal is received. */
240static volatile sig_atomic_t received_sighup = 0;
241static volatile sig_atomic_t received_sigterm = 0;
242
243/* session identifier, used by RSA-auth */
244u_char session_id[16];
245
246/* same for ssh2 */
247u_char *session_id2 = NULL;
248u_int session_id2_len = 0;
249
250/* record remote hostname or ip */
251u_int utmp_len = MAXHOSTNAMELEN;
252
253/* options.max_startup sized array of fd ints */
254int *startup_pipes = NULL;
255int startup_pipe;		/* in child */
256
257/* variables used for privilege separation */
258int use_privsep = -1;
259struct monitor *pmonitor = NULL;
260int privsep_is_preauth = 1;
261
262/* global authentication context */
263Authctxt *the_authctxt = NULL;
264
265/* sshd_config buffer */
266Buffer cfg;
267
268/* message to be displayed after login */
269Buffer loginmsg;
270
271/* Unprivileged user */
272struct passwd *privsep_pw = NULL;
273
274/* Prototypes for various functions defined later in this file. */
275void destroy_sensitive_data(void);
276void demote_sensitive_data(void);
277
278static void do_ssh1_kex(void);
279static void do_ssh2_kex(void);
280
281/*
282 * Close all listening sockets
283 */
284static void
285close_listen_socks(void)
286{
287	int i;
288
289	for (i = 0; i < num_listen_socks; i++)
290		close(listen_socks[i]);
291	num_listen_socks = -1;
292}
293
294static void
295close_startup_pipes(void)
296{
297	int i;
298
299	if (startup_pipes)
300		for (i = 0; i < options.max_startups; i++)
301			if (startup_pipes[i] != -1)
302				close(startup_pipes[i]);
303}
304
305/*
306 * Signal handler for SIGHUP.  Sshd execs itself when it receives SIGHUP;
307 * the effect is to reread the configuration file (and to regenerate
308 * the server key).
309 */
310
311/*ARGSUSED*/
312static void
313sighup_handler(int sig)
314{
315	int save_errno = errno;
316
317	received_sighup = 1;
318	signal(SIGHUP, sighup_handler);
319	errno = save_errno;
320}
321
322/*
323 * Called from the main program after receiving SIGHUP.
324 * Restarts the server.
325 */
326static void
327sighup_restart(void)
328{
329	logit("Received SIGHUP; restarting.");
330	platform_pre_restart();
331	close_listen_socks();
332	close_startup_pipes();
333	alarm(0);  /* alarm timer persists across exec */
334	signal(SIGHUP, SIG_IGN); /* will be restored after exec */
335	execv(saved_argv[0], saved_argv);
336	logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
337	    strerror(errno));
338	exit(1);
339}
340
341/*
342 * Generic signal handler for terminating signals in the master daemon.
343 */
344/*ARGSUSED*/
345static void
346sigterm_handler(int sig)
347{
348	received_sigterm = sig;
349}
350
351/*
352 * SIGCHLD handler.  This is called whenever a child dies.  This will then
353 * reap any zombies left by exited children.
354 */
355/*ARGSUSED*/
356static void
357main_sigchld_handler(int sig)
358{
359	int save_errno = errno;
360	pid_t pid;
361	int status;
362
363	while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
364	    (pid < 0 && errno == EINTR))
365		;
366
367	signal(SIGCHLD, main_sigchld_handler);
368	errno = save_errno;
369}
370
371/*
372 * Signal handler for the alarm after the login grace period has expired.
373 */
374/*ARGSUSED*/
375static void
376grace_alarm_handler(int sig)
377{
378	if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
379		kill(pmonitor->m_pid, SIGALRM);
380
381	/*
382	 * Try to kill any processes that we have spawned, E.g. authorized
383	 * keys command helpers.
384	 */
385	if (getpgid(0) == getpid()) {
386		signal(SIGTERM, SIG_IGN);
387		kill(0, SIGTERM);
388	}
389
390	/* Log error and exit. */
391	sigdie("Timeout before authentication for %s", get_remote_ipaddr());
392}
393
394/*
395 * Signal handler for the key regeneration alarm.  Note that this
396 * alarm only occurs in the daemon waiting for connections, and it does not
397 * do anything with the private key or random state before forking.
398 * Thus there should be no concurrency control/asynchronous execution
399 * problems.
400 */
401static void
402generate_ephemeral_server_key(void)
403{
404	verbose("Generating %s%d bit RSA key.",
405	    sensitive_data.server_key ? "new " : "", options.server_key_bits);
406	if (sensitive_data.server_key != NULL)
407		key_free(sensitive_data.server_key);
408	sensitive_data.server_key = key_generate(KEY_RSA1,
409	    options.server_key_bits);
410	verbose("RSA key generation complete.");
411
412	arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
413}
414
415/*ARGSUSED*/
416static void
417key_regeneration_alarm(int sig)
418{
419	int save_errno = errno;
420
421	signal(SIGALRM, SIG_DFL);
422	errno = save_errno;
423	key_do_regen = 1;
424}
425
426static void
427sshd_exchange_identification(int sock_in, int sock_out)
428{
429	u_int i;
430	int mismatch;
431	int remote_major, remote_minor;
432	int major, minor;
433	char *s, *newline = "\n";
434	char buf[256];			/* Must not be larger than remote_version. */
435	char remote_version[256];	/* Must be at least as big as buf. */
436
437	if ((options.protocol & SSH_PROTO_1) &&
438	    (options.protocol & SSH_PROTO_2)) {
439		major = PROTOCOL_MAJOR_1;
440		minor = 99;
441	} else if (options.protocol & SSH_PROTO_2) {
442		major = PROTOCOL_MAJOR_2;
443		minor = PROTOCOL_MINOR_2;
444		newline = "\r\n";
445	} else {
446		major = PROTOCOL_MAJOR_1;
447		minor = PROTOCOL_MINOR_1;
448	}
449
450	xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s%s",
451	    major, minor, SSH_VERSION,
452	    options.hpn_disabled ? "" : SSH_VERSION_HPN,
453	    *options.version_addendum == '\0' ? "" : " ",
454	    options.version_addendum, newline);
455
456	/* Send our protocol version identification. */
457	if (roaming_atomicio(vwrite, sock_out, server_version_string,
458	    strlen(server_version_string))
459	    != strlen(server_version_string)) {
460		logit("Could not write ident string to %s", get_remote_ipaddr());
461		cleanup_exit(255);
462	}
463
464	/* Read other sides version identification. */
465	memset(buf, 0, sizeof(buf));
466	for (i = 0; i < sizeof(buf) - 1; i++) {
467		if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
468			logit("Did not receive identification string from %s",
469			    get_remote_ipaddr());
470			cleanup_exit(255);
471		}
472		if (buf[i] == '\r') {
473			buf[i] = 0;
474			/* Kludge for F-Secure Macintosh < 1.0.2 */
475			if (i == 12 &&
476			    strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
477				break;
478			continue;
479		}
480		if (buf[i] == '\n') {
481			buf[i] = 0;
482			break;
483		}
484	}
485	buf[sizeof(buf) - 1] = 0;
486	client_version_string = xstrdup(buf);
487
488	/*
489	 * Check that the versions match.  In future this might accept
490	 * several versions and set appropriate flags to handle them.
491	 */
492	if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
493	    &remote_major, &remote_minor, remote_version) != 3) {
494		s = "Protocol mismatch.\n";
495		(void) atomicio(vwrite, sock_out, s, strlen(s));
496		logit("Bad protocol version identification '%.100s' "
497		    "from %s port %d", client_version_string,
498		    get_remote_ipaddr(), get_remote_port());
499		close(sock_in);
500		close(sock_out);
501		cleanup_exit(255);
502	}
503	debug("Client protocol version %d.%d; client software version %.100s",
504	    remote_major, remote_minor, remote_version);
505
506	compat_datafellows(remote_version);
507
508	if ((datafellows & SSH_BUG_PROBE) != 0) {
509		logit("probed from %s with %s.  Don't panic.",
510		    get_remote_ipaddr(), client_version_string);
511		cleanup_exit(255);
512	}
513	if ((datafellows & SSH_BUG_SCANNER) != 0) {
514		logit("scanned from %s with %s.  Don't panic.",
515		    get_remote_ipaddr(), client_version_string);
516		cleanup_exit(255);
517	}
518	if ((datafellows & SSH_BUG_RSASIGMD5) != 0) {
519		logit("Client version \"%.100s\" uses unsafe RSA signature "
520		    "scheme; disabling use of RSA keys", remote_version);
521	}
522	if ((datafellows & SSH_BUG_DERIVEKEY) != 0) {
523		fatal("Client version \"%.100s\" uses unsafe key agreement; "
524		    "refusing connection", remote_version);
525	}
526
527	mismatch = 0;
528	switch (remote_major) {
529	case 1:
530		if (remote_minor == 99) {
531			if (options.protocol & SSH_PROTO_2)
532				enable_compat20();
533			else
534				mismatch = 1;
535			break;
536		}
537		if (!(options.protocol & SSH_PROTO_1)) {
538			mismatch = 1;
539			break;
540		}
541		if (remote_minor < 3) {
542			packet_disconnect("Your ssh version is too old and "
543			    "is no longer supported.  Please install a newer version.");
544		} else if (remote_minor == 3) {
545			/* note that this disables agent-forwarding */
546			enable_compat13();
547		}
548		break;
549	case 2:
550		if (options.protocol & SSH_PROTO_2) {
551			enable_compat20();
552			break;
553		}
554		/* FALLTHROUGH */
555	default:
556		mismatch = 1;
557		break;
558	}
559	chop(server_version_string);
560	debug("Local version string %.200s", server_version_string);
561
562	if (mismatch) {
563		s = "Protocol major versions differ.\n";
564		(void) atomicio(vwrite, sock_out, s, strlen(s));
565		close(sock_in);
566		close(sock_out);
567		logit("Protocol major versions differ for %s: %.200s vs. %.200s",
568		    get_remote_ipaddr(),
569		    server_version_string, client_version_string);
570		cleanup_exit(255);
571	}
572}
573
574/* Destroy the host and server keys.  They will no longer be needed. */
575void
576destroy_sensitive_data(void)
577{
578	int i;
579
580	if (sensitive_data.server_key) {
581		key_free(sensitive_data.server_key);
582		sensitive_data.server_key = NULL;
583	}
584	for (i = 0; i < options.num_host_key_files; i++) {
585		if (sensitive_data.host_keys[i]) {
586			key_free(sensitive_data.host_keys[i]);
587			sensitive_data.host_keys[i] = NULL;
588		}
589		if (sensitive_data.host_certificates[i]) {
590			key_free(sensitive_data.host_certificates[i]);
591			sensitive_data.host_certificates[i] = NULL;
592		}
593	}
594	sensitive_data.ssh1_host_key = NULL;
595	memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
596}
597
598/* Demote private to public keys for network child */
599void
600demote_sensitive_data(void)
601{
602	Key *tmp;
603	int i;
604
605	if (sensitive_data.server_key) {
606		tmp = key_demote(sensitive_data.server_key);
607		key_free(sensitive_data.server_key);
608		sensitive_data.server_key = tmp;
609	}
610
611	for (i = 0; i < options.num_host_key_files; i++) {
612		if (sensitive_data.host_keys[i]) {
613			tmp = key_demote(sensitive_data.host_keys[i]);
614			key_free(sensitive_data.host_keys[i]);
615			sensitive_data.host_keys[i] = tmp;
616			if (tmp->type == KEY_RSA1)
617				sensitive_data.ssh1_host_key = tmp;
618		}
619		/* Certs do not need demotion */
620	}
621
622	/* We do not clear ssh1_host key and cookie.  XXX - Okay Niels? */
623}
624
625static void
626privsep_preauth_child(void)
627{
628	u_int32_t rnd[256];
629	gid_t gidset[1];
630
631	/* Enable challenge-response authentication for privilege separation */
632	privsep_challenge_enable();
633
634	arc4random_stir();
635	arc4random_buf(rnd, sizeof(rnd));
636	RAND_seed(rnd, sizeof(rnd));
637	bzero(rnd, sizeof(rnd));
638
639	/* Demote the private keys to public keys. */
640	demote_sensitive_data();
641
642	/* Change our root directory */
643	if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
644		fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
645		    strerror(errno));
646	if (chdir("/") == -1)
647		fatal("chdir(\"/\"): %s", strerror(errno));
648
649	/* Drop our privileges */
650	debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
651	    (u_int)privsep_pw->pw_gid);
652#if 0
653	/* XXX not ready, too heavy after chroot */
654	do_setusercontext(privsep_pw);
655#else
656	gidset[0] = privsep_pw->pw_gid;
657	if (setgroups(1, gidset) < 0)
658		fatal("setgroups: %.100s", strerror(errno));
659	permanently_set_uid(privsep_pw);
660#endif
661}
662
663static int
664privsep_preauth(Authctxt *authctxt)
665{
666	int status;
667	pid_t pid;
668	struct ssh_sandbox *box = NULL;
669
670	/* Set up unprivileged child process to deal with network data */
671	pmonitor = monitor_init();
672	/* Store a pointer to the kex for later rekeying */
673	pmonitor->m_pkex = &xxx_kex;
674
675	if (use_privsep == PRIVSEP_ON)
676		box = ssh_sandbox_init(pmonitor);
677	pid = fork();
678	if (pid == -1) {
679		fatal("fork of unprivileged child failed");
680	} else if (pid != 0) {
681		debug2("Network child is on pid %ld", (long)pid);
682
683		pmonitor->m_pid = pid;
684		if (have_agent)
685			auth_conn = ssh_get_authentication_connection();
686		if (box != NULL)
687			ssh_sandbox_parent_preauth(box, pid);
688		monitor_child_preauth(authctxt, pmonitor);
689
690		/* Sync memory */
691		monitor_sync(pmonitor);
692
693		/* Wait for the child's exit status */
694		while (waitpid(pid, &status, 0) < 0) {
695			if (errno == EINTR)
696				continue;
697			pmonitor->m_pid = -1;
698			fatal("%s: waitpid: %s", __func__, strerror(errno));
699		}
700		privsep_is_preauth = 0;
701		pmonitor->m_pid = -1;
702		if (WIFEXITED(status)) {
703			if (WEXITSTATUS(status) != 0)
704				fatal("%s: preauth child exited with status %d",
705				    __func__, WEXITSTATUS(status));
706		} else if (WIFSIGNALED(status))
707			fatal("%s: preauth child terminated by signal %d",
708			    __func__, WTERMSIG(status));
709		if (box != NULL)
710			ssh_sandbox_parent_finish(box);
711		return 1;
712	} else {
713		/* child */
714		close(pmonitor->m_sendfd);
715		close(pmonitor->m_log_recvfd);
716
717		/* Arrange for logging to be sent to the monitor */
718		set_log_handler(mm_log_handler, pmonitor);
719
720		/* Demote the child */
721		if (getuid() == 0 || geteuid() == 0)
722			privsep_preauth_child();
723		setproctitle("%s", "[net]");
724		if (box != NULL)
725			ssh_sandbox_child(box);
726
727		return 0;
728	}
729}
730
731static void
732privsep_postauth(Authctxt *authctxt)
733{
734	u_int32_t rnd[256];
735
736#ifdef DISABLE_FD_PASSING
737	if (1) {
738#else
739	if (authctxt->pw->pw_uid == 0 || options.use_login) {
740#endif
741		/* File descriptor passing is broken or root login */
742		use_privsep = 0;
743		goto skip;
744	}
745
746	/* New socket pair */
747	monitor_reinit(pmonitor);
748
749	pmonitor->m_pid = fork();
750	if (pmonitor->m_pid == -1)
751		fatal("fork of unprivileged child failed");
752	else if (pmonitor->m_pid != 0) {
753		verbose("User child is on pid %ld", (long)pmonitor->m_pid);
754		buffer_clear(&loginmsg);
755		monitor_child_postauth(pmonitor);
756
757		/* NEVERREACHED */
758		exit(0);
759	}
760
761	/* child */
762
763	close(pmonitor->m_sendfd);
764	pmonitor->m_sendfd = -1;
765
766	/* Demote the private keys to public keys. */
767	demote_sensitive_data();
768
769	arc4random_stir();
770	arc4random_buf(rnd, sizeof(rnd));
771	RAND_seed(rnd, sizeof(rnd));
772	bzero(rnd, sizeof(rnd));
773
774	/* Drop privileges */
775	do_setusercontext(authctxt->pw);
776
777 skip:
778	/* It is safe now to apply the key state */
779	monitor_apply_keystate(pmonitor);
780
781	/*
782	 * Tell the packet layer that authentication was successful, since
783	 * this information is not part of the key state.
784	 */
785	packet_set_authenticated();
786}
787
788static char *
789list_hostkey_types(void)
790{
791	Buffer b;
792	const char *p;
793	char *ret;
794	int i;
795	Key *key;
796
797	buffer_init(&b);
798	for (i = 0; i < options.num_host_key_files; i++) {
799		key = sensitive_data.host_keys[i];
800		if (key == NULL)
801			key = sensitive_data.host_pubkeys[i];
802		if (key == NULL)
803			continue;
804		switch (key->type) {
805		case KEY_RSA:
806		case KEY_DSA:
807		case KEY_ECDSA:
808		case KEY_ED25519:
809			if (buffer_len(&b) > 0)
810				buffer_append(&b, ",", 1);
811			p = key_ssh_name(key);
812			buffer_append(&b, p, strlen(p));
813			break;
814		}
815		/* If the private key has a cert peer, then list that too */
816		key = sensitive_data.host_certificates[i];
817		if (key == NULL)
818			continue;
819		switch (key->type) {
820		case KEY_RSA_CERT_V00:
821		case KEY_DSA_CERT_V00:
822		case KEY_RSA_CERT:
823		case KEY_DSA_CERT:
824		case KEY_ECDSA_CERT:
825		case KEY_ED25519_CERT:
826			if (buffer_len(&b) > 0)
827				buffer_append(&b, ",", 1);
828			p = key_ssh_name(key);
829			buffer_append(&b, p, strlen(p));
830			break;
831		}
832	}
833	buffer_append(&b, "\0", 1);
834	ret = xstrdup(buffer_ptr(&b));
835	buffer_free(&b);
836	debug("list_hostkey_types: %s", ret);
837	return ret;
838}
839
840static Key *
841get_hostkey_by_type(int type, int need_private)
842{
843	int i;
844	Key *key;
845
846	for (i = 0; i < options.num_host_key_files; i++) {
847		switch (type) {
848		case KEY_RSA_CERT_V00:
849		case KEY_DSA_CERT_V00:
850		case KEY_RSA_CERT:
851		case KEY_DSA_CERT:
852		case KEY_ECDSA_CERT:
853		case KEY_ED25519_CERT:
854			key = sensitive_data.host_certificates[i];
855			break;
856		default:
857			key = sensitive_data.host_keys[i];
858			if (key == NULL && !need_private)
859				key = sensitive_data.host_pubkeys[i];
860			break;
861		}
862		if (key != NULL && key->type == type)
863			return need_private ?
864			    sensitive_data.host_keys[i] : key;
865	}
866	return NULL;
867}
868
869Key *
870get_hostkey_public_by_type(int type)
871{
872	return get_hostkey_by_type(type, 0);
873}
874
875Key *
876get_hostkey_private_by_type(int type)
877{
878	return get_hostkey_by_type(type, 1);
879}
880
881Key *
882get_hostkey_by_index(int ind)
883{
884	if (ind < 0 || ind >= options.num_host_key_files)
885		return (NULL);
886	return (sensitive_data.host_keys[ind]);
887}
888
889Key *
890get_hostkey_public_by_index(int ind)
891{
892	if (ind < 0 || ind >= options.num_host_key_files)
893		return (NULL);
894	return (sensitive_data.host_pubkeys[ind]);
895}
896
897int
898get_hostkey_index(Key *key)
899{
900	int i;
901
902	for (i = 0; i < options.num_host_key_files; i++) {
903		if (key_is_cert(key)) {
904			if (key == sensitive_data.host_certificates[i])
905				return (i);
906		} else {
907			if (key == sensitive_data.host_keys[i])
908				return (i);
909			if (key == sensitive_data.host_pubkeys[i])
910				return (i);
911		}
912	}
913	return (-1);
914}
915
916/*
917 * returns 1 if connection should be dropped, 0 otherwise.
918 * dropping starts at connection #max_startups_begin with a probability
919 * of (max_startups_rate/100). the probability increases linearly until
920 * all connections are dropped for startups > max_startups
921 */
922static int
923drop_connection(int startups)
924{
925	int p, r;
926
927	if (startups < options.max_startups_begin)
928		return 0;
929	if (startups >= options.max_startups)
930		return 1;
931	if (options.max_startups_rate == 100)
932		return 1;
933
934	p  = 100 - options.max_startups_rate;
935	p *= startups - options.max_startups_begin;
936	p /= options.max_startups - options.max_startups_begin;
937	p += options.max_startups_rate;
938	r = arc4random_uniform(100);
939
940	debug("drop_connection: p %d, r %d", p, r);
941	return (r < p) ? 1 : 0;
942}
943
944static void
945usage(void)
946{
947	if (options.version_addendum && *options.version_addendum != '\0')
948		fprintf(stderr, "%s%s %s, %s\n",
949		    SSH_RELEASE, options.hpn_disabled ? "" : SSH_VERSION_HPN,
950		    options.version_addendum, SSLeay_version(SSLEAY_VERSION));
951	else
952		fprintf(stderr, "%s%s, %s\n",
953		    SSH_RELEASE, options.hpn_disabled ? "" : SSH_VERSION_HPN,
954		    SSLeay_version(SSLEAY_VERSION));
955	fprintf(stderr,
956"usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
957"            [-E log_file] [-f config_file] [-g login_grace_time]\n"
958"            [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n"
959"            [-u len]\n"
960	);
961	exit(1);
962}
963
964static void
965send_rexec_state(int fd, Buffer *conf)
966{
967	Buffer m;
968
969	debug3("%s: entering fd = %d config len %d", __func__, fd,
970	    buffer_len(conf));
971
972	/*
973	 * Protocol from reexec master to child:
974	 *	string	configuration
975	 *	u_int	ephemeral_key_follows
976	 *	bignum	e		(only if ephemeral_key_follows == 1)
977	 *	bignum	n			"
978	 *	bignum	d			"
979	 *	bignum	iqmp			"
980	 *	bignum	p			"
981	 *	bignum	q			"
982	 *	string rngseed		(only if OpenSSL is not self-seeded)
983	 */
984	buffer_init(&m);
985	buffer_put_cstring(&m, buffer_ptr(conf));
986
987	if (sensitive_data.server_key != NULL &&
988	    sensitive_data.server_key->type == KEY_RSA1) {
989		buffer_put_int(&m, 1);
990		buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
991		buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
992		buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
993		buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
994		buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
995		buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
996	} else
997		buffer_put_int(&m, 0);
998
999#ifndef OPENSSL_PRNG_ONLY
1000	rexec_send_rng_seed(&m);
1001#endif
1002
1003	if (ssh_msg_send(fd, 0, &m) == -1)
1004		fatal("%s: ssh_msg_send failed", __func__);
1005
1006	buffer_free(&m);
1007
1008	debug3("%s: done", __func__);
1009}
1010
1011static void
1012recv_rexec_state(int fd, Buffer *conf)
1013{
1014	Buffer m;
1015	char *cp;
1016	u_int len;
1017
1018	debug3("%s: entering fd = %d", __func__, fd);
1019
1020	buffer_init(&m);
1021
1022	if (ssh_msg_recv(fd, &m) == -1)
1023		fatal("%s: ssh_msg_recv failed", __func__);
1024	if (buffer_get_char(&m) != 0)
1025		fatal("%s: rexec version mismatch", __func__);
1026
1027	cp = buffer_get_string(&m, &len);
1028	if (conf != NULL)
1029		buffer_append(conf, cp, len + 1);
1030	free(cp);
1031
1032	if (buffer_get_int(&m)) {
1033		if (sensitive_data.server_key != NULL)
1034			key_free(sensitive_data.server_key);
1035		sensitive_data.server_key = key_new_private(KEY_RSA1);
1036		buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
1037		buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
1038		buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
1039		buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
1040		buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
1041		buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
1042		rsa_generate_additional_parameters(
1043		    sensitive_data.server_key->rsa);
1044	}
1045
1046#ifndef OPENSSL_PRNG_ONLY
1047	rexec_recv_rng_seed(&m);
1048#endif
1049
1050	buffer_free(&m);
1051
1052	debug3("%s: done", __func__);
1053}
1054
1055/* Accept a connection from inetd */
1056static void
1057server_accept_inetd(int *sock_in, int *sock_out)
1058{
1059	int fd;
1060
1061	startup_pipe = -1;
1062	if (rexeced_flag) {
1063		close(REEXEC_CONFIG_PASS_FD);
1064		*sock_in = *sock_out = dup(STDIN_FILENO);
1065		if (!debug_flag) {
1066			startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1067			close(REEXEC_STARTUP_PIPE_FD);
1068		}
1069	} else {
1070		*sock_in = dup(STDIN_FILENO);
1071		*sock_out = dup(STDOUT_FILENO);
1072	}
1073	/*
1074	 * We intentionally do not close the descriptors 0, 1, and 2
1075	 * as our code for setting the descriptors won't work if
1076	 * ttyfd happens to be one of those.
1077	 */
1078	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1079		dup2(fd, STDIN_FILENO);
1080		dup2(fd, STDOUT_FILENO);
1081		if (!log_stderr)
1082			dup2(fd, STDERR_FILENO);
1083		if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1084			close(fd);
1085	}
1086	debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1087}
1088
1089/*
1090 * Listen for TCP connections
1091 */
1092static void
1093server_listen(void)
1094{
1095	int ret, listen_sock, on = 1;
1096	struct addrinfo *ai;
1097	char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1098	int socksize;
1099	socklen_t len;
1100
1101	for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1102		if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1103			continue;
1104		if (num_listen_socks >= MAX_LISTEN_SOCKS)
1105			fatal("Too many listen sockets. "
1106			    "Enlarge MAX_LISTEN_SOCKS");
1107		if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1108		    ntop, sizeof(ntop), strport, sizeof(strport),
1109		    NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1110			error("getnameinfo failed: %.100s",
1111			    ssh_gai_strerror(ret));
1112			continue;
1113		}
1114		/* Create socket for listening. */
1115		listen_sock = socket(ai->ai_family, ai->ai_socktype,
1116		    ai->ai_protocol);
1117		if (listen_sock < 0) {
1118			/* kernel may not support ipv6 */
1119			verbose("socket: %.100s", strerror(errno));
1120			continue;
1121		}
1122		if (set_nonblock(listen_sock) == -1) {
1123			close(listen_sock);
1124			continue;
1125		}
1126		/*
1127		 * Set socket options.
1128		 * Allow local port reuse in TIME_WAIT.
1129		 */
1130		if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1131		    &on, sizeof(on)) == -1)
1132			error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1133
1134		/* Only communicate in IPv6 over AF_INET6 sockets. */
1135		if (ai->ai_family == AF_INET6)
1136			sock_set_v6only(listen_sock);
1137
1138		debug("Bind to port %s on %s.", strport, ntop);
1139
1140		len = sizeof(socksize);
1141		getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
1142		debug("Server TCP RWIN socket size: %d", socksize);
1143		debug("HPN Buffer Size: %d", options.hpn_buffer_size);
1144
1145		/* Bind the socket to the desired port. */
1146		if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1147			error("Bind to port %s on %s failed: %.200s.",
1148			    strport, ntop, strerror(errno));
1149			close(listen_sock);
1150			continue;
1151		}
1152		listen_socks[num_listen_socks] = listen_sock;
1153		num_listen_socks++;
1154
1155		/* Start listening on the port. */
1156		if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1157			fatal("listen on [%s]:%s: %.100s",
1158			    ntop, strport, strerror(errno));
1159		logit("Server listening on %s port %s.", ntop, strport);
1160	}
1161	freeaddrinfo(options.listen_addrs);
1162
1163	if (!num_listen_socks)
1164		fatal("Cannot bind any address.");
1165}
1166
1167/*
1168 * The main TCP accept loop. Note that, for the non-debug case, returns
1169 * from this function are in a forked subprocess.
1170 */
1171static void
1172server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1173{
1174	fd_set *fdset;
1175	int i, j, ret, maxfd;
1176	int key_used = 0, startups = 0;
1177	int startup_p[2] = { -1 , -1 };
1178	struct sockaddr_storage from;
1179	socklen_t fromlen;
1180	pid_t pid;
1181	u_char rnd[256];
1182
1183	/* setup fd set for accept */
1184	fdset = NULL;
1185	maxfd = 0;
1186	for (i = 0; i < num_listen_socks; i++)
1187		if (listen_socks[i] > maxfd)
1188			maxfd = listen_socks[i];
1189	/* pipes connected to unauthenticated childs */
1190	startup_pipes = xcalloc(options.max_startups, sizeof(int));
1191	for (i = 0; i < options.max_startups; i++)
1192		startup_pipes[i] = -1;
1193
1194	/*
1195	 * Stay listening for connections until the system crashes or
1196	 * the daemon is killed with a signal.
1197	 */
1198	for (;;) {
1199		if (received_sighup)
1200			sighup_restart();
1201		if (fdset != NULL)
1202			free(fdset);
1203		fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1204		    sizeof(fd_mask));
1205
1206		for (i = 0; i < num_listen_socks; i++)
1207			FD_SET(listen_socks[i], fdset);
1208		for (i = 0; i < options.max_startups; i++)
1209			if (startup_pipes[i] != -1)
1210				FD_SET(startup_pipes[i], fdset);
1211
1212		/* Wait in select until there is a connection. */
1213		ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1214		if (ret < 0 && errno != EINTR)
1215			error("select: %.100s", strerror(errno));
1216		if (received_sigterm) {
1217			logit("Received signal %d; terminating.",
1218			    (int) received_sigterm);
1219			close_listen_socks();
1220			unlink(options.pid_file);
1221			exit(received_sigterm == SIGTERM ? 0 : 255);
1222		}
1223		if (key_used && key_do_regen) {
1224			generate_ephemeral_server_key();
1225			key_used = 0;
1226			key_do_regen = 0;
1227		}
1228		if (ret < 0)
1229			continue;
1230
1231		for (i = 0; i < options.max_startups; i++)
1232			if (startup_pipes[i] != -1 &&
1233			    FD_ISSET(startup_pipes[i], fdset)) {
1234				/*
1235				 * the read end of the pipe is ready
1236				 * if the child has closed the pipe
1237				 * after successful authentication
1238				 * or if the child has died
1239				 */
1240				close(startup_pipes[i]);
1241				startup_pipes[i] = -1;
1242				startups--;
1243			}
1244		for (i = 0; i < num_listen_socks; i++) {
1245			if (!FD_ISSET(listen_socks[i], fdset))
1246				continue;
1247			fromlen = sizeof(from);
1248			*newsock = accept(listen_socks[i],
1249			    (struct sockaddr *)&from, &fromlen);
1250			if (*newsock < 0) {
1251				if (errno != EINTR && errno != EWOULDBLOCK &&
1252				    errno != ECONNABORTED && errno != EAGAIN)
1253					error("accept: %.100s",
1254					    strerror(errno));
1255				if (errno == EMFILE || errno == ENFILE)
1256					usleep(100 * 1000);
1257				continue;
1258			}
1259			if (unset_nonblock(*newsock) == -1) {
1260				close(*newsock);
1261				continue;
1262			}
1263			if (drop_connection(startups) == 1) {
1264				debug("drop connection #%d", startups);
1265				close(*newsock);
1266				continue;
1267			}
1268			if (pipe(startup_p) == -1) {
1269				close(*newsock);
1270				continue;
1271			}
1272
1273			if (rexec_flag && socketpair(AF_UNIX,
1274			    SOCK_STREAM, 0, config_s) == -1) {
1275				error("reexec socketpair: %s",
1276				    strerror(errno));
1277				close(*newsock);
1278				close(startup_p[0]);
1279				close(startup_p[1]);
1280				continue;
1281			}
1282
1283			for (j = 0; j < options.max_startups; j++)
1284				if (startup_pipes[j] == -1) {
1285					startup_pipes[j] = startup_p[0];
1286					if (maxfd < startup_p[0])
1287						maxfd = startup_p[0];
1288					startups++;
1289					break;
1290				}
1291
1292			/*
1293			 * Got connection.  Fork a child to handle it, unless
1294			 * we are in debugging mode.
1295			 */
1296			if (debug_flag) {
1297				/*
1298				 * In debugging mode.  Close the listening
1299				 * socket, and start processing the
1300				 * connection without forking.
1301				 */
1302				debug("Server will not fork when running in debugging mode.");
1303				close_listen_socks();
1304				*sock_in = *newsock;
1305				*sock_out = *newsock;
1306				close(startup_p[0]);
1307				close(startup_p[1]);
1308				startup_pipe = -1;
1309				pid = getpid();
1310				if (rexec_flag) {
1311					send_rexec_state(config_s[0],
1312					    &cfg);
1313					close(config_s[0]);
1314				}
1315				break;
1316			}
1317
1318			/*
1319			 * Normal production daemon.  Fork, and have
1320			 * the child process the connection. The
1321			 * parent continues listening.
1322			 */
1323			platform_pre_fork();
1324			if ((pid = fork()) == 0) {
1325				/*
1326				 * Child.  Close the listening and
1327				 * max_startup sockets.  Start using
1328				 * the accepted socket. Reinitialize
1329				 * logging (since our pid has changed).
1330				 * We break out of the loop to handle
1331				 * the connection.
1332				 */
1333				platform_post_fork_child();
1334				startup_pipe = startup_p[1];
1335				close_startup_pipes();
1336				close_listen_socks();
1337				*sock_in = *newsock;
1338				*sock_out = *newsock;
1339				log_init(__progname,
1340				    options.log_level,
1341				    options.log_facility,
1342				    log_stderr);
1343				if (rexec_flag)
1344					close(config_s[0]);
1345				break;
1346			}
1347
1348			/* Parent.  Stay in the loop. */
1349			platform_post_fork_parent(pid);
1350			if (pid < 0)
1351				error("fork: %.100s", strerror(errno));
1352			else
1353				debug("Forked child %ld.", (long)pid);
1354
1355			close(startup_p[1]);
1356
1357			if (rexec_flag) {
1358				send_rexec_state(config_s[0], &cfg);
1359				close(config_s[0]);
1360				close(config_s[1]);
1361			}
1362
1363			/*
1364			 * Mark that the key has been used (it
1365			 * was "given" to the child).
1366			 */
1367			if ((options.protocol & SSH_PROTO_1) &&
1368			    key_used == 0) {
1369				/* Schedule server key regeneration alarm. */
1370				signal(SIGALRM, key_regeneration_alarm);
1371				alarm(options.key_regeneration_time);
1372				key_used = 1;
1373			}
1374
1375			close(*newsock);
1376
1377			/*
1378			 * Ensure that our random state differs
1379			 * from that of the child
1380			 */
1381			arc4random_stir();
1382			arc4random_buf(rnd, sizeof(rnd));
1383			RAND_seed(rnd, sizeof(rnd));
1384			bzero(rnd, sizeof(rnd));
1385		}
1386
1387		/* child process check (or debug mode) */
1388		if (num_listen_socks < 0)
1389			break;
1390	}
1391}
1392
1393
1394/*
1395 * Main program for the daemon.
1396 */
1397int
1398main(int ac, char **av)
1399{
1400	extern char *optarg;
1401	extern int optind;
1402	int opt, i, j, on = 1;
1403	int sock_in = -1, sock_out = -1, newsock = -1;
1404	const char *remote_ip;
1405	int remote_port;
1406	char *line, *logfile = NULL;
1407	int config_s[2] = { -1 , -1 };
1408	u_int n;
1409	u_int64_t ibytes, obytes;
1410	mode_t new_umask;
1411	Key *key;
1412	Key *pubkey;
1413	int keytype;
1414	Authctxt *authctxt;
1415	struct connection_info *connection_info = get_connection_info(0, 0);
1416
1417#ifdef HAVE_SECUREWARE
1418	(void)set_auth_parameters(ac, av);
1419#endif
1420	__progname = ssh_get_progname(av[0]);
1421
1422	/* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1423	saved_argc = ac;
1424	rexec_argc = ac;
1425	saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1426	for (i = 0; i < ac; i++)
1427		saved_argv[i] = xstrdup(av[i]);
1428	saved_argv[i] = NULL;
1429
1430#ifndef HAVE_SETPROCTITLE
1431	/* Prepare for later setproctitle emulation */
1432	compat_init_setproctitle(ac, av);
1433	av = saved_argv;
1434#endif
1435
1436	if (geteuid() == 0 && setgroups(0, NULL) == -1)
1437		debug("setgroups(): %.200s", strerror(errno));
1438
1439	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1440	sanitise_stdfd();
1441
1442	/* Initialize configuration options to their default values. */
1443	initialize_server_options(&options);
1444
1445	/* Parse command-line arguments. */
1446	while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) {
1447		switch (opt) {
1448		case '4':
1449			options.address_family = AF_INET;
1450			break;
1451		case '6':
1452			options.address_family = AF_INET6;
1453			break;
1454		case 'f':
1455			config_file_name = optarg;
1456			break;
1457		case 'c':
1458			if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1459				fprintf(stderr, "too many host certificates.\n");
1460				exit(1);
1461			}
1462			options.host_cert_files[options.num_host_cert_files++] =
1463			   derelativise_path(optarg);
1464			break;
1465		case 'd':
1466			if (debug_flag == 0) {
1467				debug_flag = 1;
1468				options.log_level = SYSLOG_LEVEL_DEBUG1;
1469			} else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1470				options.log_level++;
1471			break;
1472		case 'D':
1473			no_daemon_flag = 1;
1474			break;
1475		case 'E':
1476			logfile = xstrdup(optarg);
1477			/* FALLTHROUGH */
1478		case 'e':
1479			log_stderr = 1;
1480			break;
1481		case 'i':
1482			inetd_flag = 1;
1483			break;
1484		case 'r':
1485			rexec_flag = 0;
1486			break;
1487		case 'R':
1488			rexeced_flag = 1;
1489			inetd_flag = 1;
1490			break;
1491		case 'Q':
1492			/* ignored */
1493			break;
1494		case 'q':
1495			options.log_level = SYSLOG_LEVEL_QUIET;
1496			break;
1497		case 'b':
1498			options.server_key_bits = (int)strtonum(optarg, 256,
1499			    32768, NULL);
1500			break;
1501		case 'p':
1502			options.ports_from_cmdline = 1;
1503			if (options.num_ports >= MAX_PORTS) {
1504				fprintf(stderr, "too many ports.\n");
1505				exit(1);
1506			}
1507			options.ports[options.num_ports++] = a2port(optarg);
1508			if (options.ports[options.num_ports-1] <= 0) {
1509				fprintf(stderr, "Bad port number.\n");
1510				exit(1);
1511			}
1512			break;
1513		case 'g':
1514			if ((options.login_grace_time = convtime(optarg)) == -1) {
1515				fprintf(stderr, "Invalid login grace time.\n");
1516				exit(1);
1517			}
1518			break;
1519		case 'k':
1520			if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1521				fprintf(stderr, "Invalid key regeneration interval.\n");
1522				exit(1);
1523			}
1524			break;
1525		case 'h':
1526			if (options.num_host_key_files >= MAX_HOSTKEYS) {
1527				fprintf(stderr, "too many host keys.\n");
1528				exit(1);
1529			}
1530			options.host_key_files[options.num_host_key_files++] =
1531			   derelativise_path(optarg);
1532			break;
1533		case 't':
1534			test_flag = 1;
1535			break;
1536		case 'T':
1537			test_flag = 2;
1538			break;
1539		case 'C':
1540			if (parse_server_match_testspec(connection_info,
1541			    optarg) == -1)
1542				exit(1);
1543			break;
1544		case 'u':
1545			utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1546			if (utmp_len > MAXHOSTNAMELEN) {
1547				fprintf(stderr, "Invalid utmp length.\n");
1548				exit(1);
1549			}
1550			break;
1551		case 'o':
1552			line = xstrdup(optarg);
1553			if (process_server_config_line(&options, line,
1554			    "command-line", 0, NULL, NULL) != 0)
1555				exit(1);
1556			free(line);
1557			break;
1558		case '?':
1559		default:
1560			usage();
1561			break;
1562		}
1563	}
1564	if (rexeced_flag || inetd_flag)
1565		rexec_flag = 0;
1566	if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1567		fatal("sshd re-exec requires execution with an absolute path");
1568	if (rexeced_flag)
1569		closefrom(REEXEC_MIN_FREE_FD);
1570	else
1571		closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1572
1573	OpenSSL_add_all_algorithms();
1574
1575	/* If requested, redirect the logs to the specified logfile. */
1576	if (logfile != NULL) {
1577		log_redirect_stderr_to(logfile);
1578		free(logfile);
1579	}
1580	/*
1581	 * Force logging to stderr until we have loaded the private host
1582	 * key (unless started from inetd)
1583	 */
1584	log_init(__progname,
1585	    options.log_level == SYSLOG_LEVEL_NOT_SET ?
1586	    SYSLOG_LEVEL_INFO : options.log_level,
1587	    options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1588	    SYSLOG_FACILITY_AUTH : options.log_facility,
1589	    log_stderr || !inetd_flag);
1590
1591	/*
1592	 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1593	 * root's environment
1594	 */
1595	if (getenv("KRB5CCNAME") != NULL)
1596		(void) unsetenv("KRB5CCNAME");
1597
1598#ifdef _UNICOS
1599	/* Cray can define user privs drop all privs now!
1600	 * Not needed on PRIV_SU systems!
1601	 */
1602	drop_cray_privs();
1603#endif
1604
1605	sensitive_data.server_key = NULL;
1606	sensitive_data.ssh1_host_key = NULL;
1607	sensitive_data.have_ssh1_key = 0;
1608	sensitive_data.have_ssh2_key = 0;
1609
1610	/*
1611	 * If we're doing an extended config test, make sure we have all of
1612	 * the parameters we need.  If we're not doing an extended test,
1613	 * do not silently ignore connection test params.
1614	 */
1615	if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0)
1616		fatal("user, host and addr are all required when testing "
1617		   "Match configs");
1618	if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0)
1619		fatal("Config test connection parameter (-C) provided without "
1620		   "test mode (-T)");
1621
1622	/* Fetch our configuration */
1623	buffer_init(&cfg);
1624	if (rexeced_flag)
1625		recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1626	else
1627		load_server_config(config_file_name, &cfg);
1628
1629	parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1630	    &cfg, NULL);
1631
1632	seed_rng();
1633
1634	/* Fill in default values for those options not explicitly set. */
1635	fill_default_server_options(&options);
1636
1637	/* challenge-response is implemented via keyboard interactive */
1638	if (options.challenge_response_authentication)
1639		options.kbd_interactive_authentication = 1;
1640
1641	/* Check that options are sensible */
1642	if (options.authorized_keys_command_user == NULL &&
1643	    (options.authorized_keys_command != NULL &&
1644	    strcasecmp(options.authorized_keys_command, "none") != 0))
1645		fatal("AuthorizedKeysCommand set without "
1646		    "AuthorizedKeysCommandUser");
1647
1648	/*
1649	 * Check whether there is any path through configured auth methods.
1650	 * Unfortunately it is not possible to verify this generally before
1651	 * daemonisation in the presence of Match block, but this catches
1652	 * and warns for trivial misconfigurations that could break login.
1653	 */
1654	if (options.num_auth_methods != 0) {
1655		if ((options.protocol & SSH_PROTO_1))
1656			fatal("AuthenticationMethods is not supported with "
1657			    "SSH protocol 1");
1658		for (n = 0; n < options.num_auth_methods; n++) {
1659			if (auth2_methods_valid(options.auth_methods[n],
1660			    1) == 0)
1661				break;
1662		}
1663		if (n >= options.num_auth_methods)
1664			fatal("AuthenticationMethods cannot be satisfied by "
1665			    "enabled authentication methods");
1666	}
1667
1668	/* set default channel AF */
1669	channel_set_af(options.address_family);
1670
1671	/* Check that there are no remaining arguments. */
1672	if (optind < ac) {
1673		fprintf(stderr, "Extra argument %s.\n", av[optind]);
1674		exit(1);
1675	}
1676
1677	debug("sshd version %.100s%.100s%s%.100s, %.100s",
1678	    SSH_RELEASE,
1679	    options.hpn_disabled ? "" : SSH_VERSION_HPN,
1680	    *options.version_addendum == '\0' ? "" : " ",
1681	    options.version_addendum,
1682	    SSLeay_version(SSLEAY_VERSION));
1683
1684	/* Store privilege separation user for later use if required. */
1685	if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1686		if (use_privsep || options.kerberos_authentication)
1687			fatal("Privilege separation user %s does not exist",
1688			    SSH_PRIVSEP_USER);
1689	} else {
1690		memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1691		privsep_pw = pwcopy(privsep_pw);
1692		free(privsep_pw->pw_passwd);
1693		privsep_pw->pw_passwd = xstrdup("*");
1694	}
1695	endpwent();
1696
1697	/* load host keys */
1698	sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1699	    sizeof(Key *));
1700	sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1701	    sizeof(Key *));
1702	for (i = 0; i < options.num_host_key_files; i++) {
1703		sensitive_data.host_keys[i] = NULL;
1704		sensitive_data.host_pubkeys[i] = NULL;
1705	}
1706
1707	if (options.host_key_agent) {
1708		if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1709			setenv(SSH_AUTHSOCKET_ENV_NAME,
1710			    options.host_key_agent, 1);
1711		have_agent = ssh_agent_present();
1712	}
1713
1714	for (i = 0; i < options.num_host_key_files; i++) {
1715		key = key_load_private(options.host_key_files[i], "", NULL);
1716		pubkey = key_load_public(options.host_key_files[i], NULL);
1717		sensitive_data.host_keys[i] = key;
1718		sensitive_data.host_pubkeys[i] = pubkey;
1719
1720		if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 &&
1721		    have_agent) {
1722			debug("will rely on agent for hostkey %s",
1723			    options.host_key_files[i]);
1724			keytype = pubkey->type;
1725		} else if (key != NULL) {
1726			keytype = key->type;
1727		} else {
1728			error("Could not load host key: %s",
1729			    options.host_key_files[i]);
1730			sensitive_data.host_keys[i] = NULL;
1731			sensitive_data.host_pubkeys[i] = NULL;
1732			continue;
1733		}
1734
1735		switch (keytype) {
1736		case KEY_RSA1:
1737			sensitive_data.ssh1_host_key = key;
1738			sensitive_data.have_ssh1_key = 1;
1739			break;
1740		case KEY_RSA:
1741		case KEY_DSA:
1742		case KEY_ECDSA:
1743		case KEY_ED25519:
1744			sensitive_data.have_ssh2_key = 1;
1745			break;
1746		}
1747		debug("private host key: #%d type %d %s", i, keytype,
1748		    key_type(key ? key : pubkey));
1749	}
1750	if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1751		logit("Disabling protocol version 1. Could not load host key");
1752		options.protocol &= ~SSH_PROTO_1;
1753	}
1754	if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1755		logit("Disabling protocol version 2. Could not load host key");
1756		options.protocol &= ~SSH_PROTO_2;
1757	}
1758	if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1759		logit("sshd: no hostkeys available -- exiting.");
1760		exit(1);
1761	}
1762
1763	/*
1764	 * Load certificates. They are stored in an array at identical
1765	 * indices to the public keys that they relate to.
1766	 */
1767	sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1768	    sizeof(Key *));
1769	for (i = 0; i < options.num_host_key_files; i++)
1770		sensitive_data.host_certificates[i] = NULL;
1771
1772	for (i = 0; i < options.num_host_cert_files; i++) {
1773		key = key_load_public(options.host_cert_files[i], NULL);
1774		if (key == NULL) {
1775			error("Could not load host certificate: %s",
1776			    options.host_cert_files[i]);
1777			continue;
1778		}
1779		if (!key_is_cert(key)) {
1780			error("Certificate file is not a certificate: %s",
1781			    options.host_cert_files[i]);
1782			key_free(key);
1783			continue;
1784		}
1785		/* Find matching private key */
1786		for (j = 0; j < options.num_host_key_files; j++) {
1787			if (key_equal_public(key,
1788			    sensitive_data.host_keys[j])) {
1789				sensitive_data.host_certificates[j] = key;
1790				break;
1791			}
1792		}
1793		if (j >= options.num_host_key_files) {
1794			error("No matching private key for certificate: %s",
1795			    options.host_cert_files[i]);
1796			key_free(key);
1797			continue;
1798		}
1799		sensitive_data.host_certificates[j] = key;
1800		debug("host certificate: #%d type %d %s", j, key->type,
1801		    key_type(key));
1802	}
1803	/* Check certain values for sanity. */
1804	if (options.protocol & SSH_PROTO_1) {
1805		if (options.server_key_bits < 512 ||
1806		    options.server_key_bits > 32768) {
1807			fprintf(stderr, "Bad server key size.\n");
1808			exit(1);
1809		}
1810		/*
1811		 * Check that server and host key lengths differ sufficiently. This
1812		 * is necessary to make double encryption work with rsaref. Oh, I
1813		 * hate software patents. I dont know if this can go? Niels
1814		 */
1815		if (options.server_key_bits >
1816		    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1817		    SSH_KEY_BITS_RESERVED && options.server_key_bits <
1818		    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1819		    SSH_KEY_BITS_RESERVED) {
1820			options.server_key_bits =
1821			    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1822			    SSH_KEY_BITS_RESERVED;
1823			debug("Forcing server key to %d bits to make it differ from host key.",
1824			    options.server_key_bits);
1825		}
1826	}
1827
1828	if (use_privsep) {
1829		struct stat st;
1830
1831		if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1832		    (S_ISDIR(st.st_mode) == 0))
1833			fatal("Missing privilege separation directory: %s",
1834			    _PATH_PRIVSEP_CHROOT_DIR);
1835
1836#ifdef HAVE_CYGWIN
1837		if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1838		    (st.st_uid != getuid () ||
1839		    (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1840#else
1841		if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1842#endif
1843			fatal("%s must be owned by root and not group or "
1844			    "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1845	}
1846
1847	if (test_flag > 1) {
1848		if (server_match_spec_complete(connection_info) == 1)
1849			parse_server_match_config(&options, connection_info);
1850		dump_config(&options);
1851	}
1852
1853	/* Configuration looks good, so exit if in test mode. */
1854	if (test_flag)
1855		exit(0);
1856
1857	/*
1858	 * Clear out any supplemental groups we may have inherited.  This
1859	 * prevents inadvertent creation of files with bad modes (in the
1860	 * portable version at least, it's certainly possible for PAM
1861	 * to create a file, and we can't control the code in every
1862	 * module which might be used).
1863	 */
1864	if (setgroups(0, NULL) < 0)
1865		debug("setgroups() failed: %.200s", strerror(errno));
1866
1867	if (rexec_flag) {
1868		rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1869		for (i = 0; i < rexec_argc; i++) {
1870			debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1871			rexec_argv[i] = saved_argv[i];
1872		}
1873		rexec_argv[rexec_argc] = "-R";
1874		rexec_argv[rexec_argc + 1] = NULL;
1875	}
1876
1877	/* Ensure that umask disallows at least group and world write */
1878	new_umask = umask(0077) | 0022;
1879	(void) umask(new_umask);
1880
1881	/* Initialize the log (it is reinitialized below in case we forked). */
1882	if (debug_flag && (!inetd_flag || rexeced_flag))
1883		log_stderr = 1;
1884	log_init(__progname, options.log_level, options.log_facility, log_stderr);
1885
1886	/*
1887	 * If not in debugging mode, and not started from inetd, disconnect
1888	 * from the controlling terminal, and fork.  The original process
1889	 * exits.
1890	 */
1891	if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1892#ifdef TIOCNOTTY
1893		int fd;
1894#endif /* TIOCNOTTY */
1895		if (daemon(0, 0) < 0)
1896			fatal("daemon() failed: %.200s", strerror(errno));
1897
1898		/* Disconnect from the controlling tty. */
1899#ifdef TIOCNOTTY
1900		fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1901		if (fd >= 0) {
1902			(void) ioctl(fd, TIOCNOTTY, NULL);
1903			close(fd);
1904		}
1905#endif /* TIOCNOTTY */
1906	}
1907	/* Reinitialize the log (because of the fork above). */
1908	log_init(__progname, options.log_level, options.log_facility, log_stderr);
1909
1910	/* Avoid killing the process in high-pressure swapping environments. */
1911	if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1912		debug("madvise(): %.200s", strerror(errno));
1913
1914	/* Chdir to the root directory so that the current disk can be
1915	   unmounted if desired. */
1916	if (chdir("/") == -1)
1917		error("chdir(\"/\"): %s", strerror(errno));
1918
1919	/* ignore SIGPIPE */
1920	signal(SIGPIPE, SIG_IGN);
1921
1922	/* Get a connection, either from inetd or a listening TCP socket */
1923	if (inetd_flag) {
1924		server_accept_inetd(&sock_in, &sock_out);
1925	} else {
1926		platform_pre_listen();
1927		server_listen();
1928
1929		if (options.protocol & SSH_PROTO_1)
1930			generate_ephemeral_server_key();
1931
1932		signal(SIGHUP, sighup_handler);
1933		signal(SIGCHLD, main_sigchld_handler);
1934		signal(SIGTERM, sigterm_handler);
1935		signal(SIGQUIT, sigterm_handler);
1936
1937		/*
1938		 * Write out the pid file after the sigterm handler
1939		 * is setup and the listen sockets are bound
1940		 */
1941		if (!debug_flag) {
1942			FILE *f = fopen(options.pid_file, "w");
1943
1944			if (f == NULL) {
1945				error("Couldn't create pid file \"%s\": %s",
1946				    options.pid_file, strerror(errno));
1947			} else {
1948				fprintf(f, "%ld\n", (long) getpid());
1949				fclose(f);
1950			}
1951		}
1952
1953		/* Accept a connection and return in a forked child */
1954		server_accept_loop(&sock_in, &sock_out,
1955		    &newsock, config_s);
1956	}
1957
1958	/* This is the child processing a new connection. */
1959	setproctitle("%s", "[accepted]");
1960
1961	/*
1962	 * Create a new session and process group since the 4.4BSD
1963	 * setlogin() affects the entire process group.  We don't
1964	 * want the child to be able to affect the parent.
1965	 */
1966#if !defined(SSHD_ACQUIRES_CTTY)
1967	/*
1968	 * If setsid is called, on some platforms sshd will later acquire a
1969	 * controlling terminal which will result in "could not set
1970	 * controlling tty" errors.
1971	 */
1972	if (!debug_flag && !inetd_flag && setsid() < 0)
1973		error("setsid: %.100s", strerror(errno));
1974#endif
1975
1976	if (rexec_flag) {
1977		int fd;
1978
1979		debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1980		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1981		dup2(newsock, STDIN_FILENO);
1982		dup2(STDIN_FILENO, STDOUT_FILENO);
1983		if (startup_pipe == -1)
1984			close(REEXEC_STARTUP_PIPE_FD);
1985		else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
1986			dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1987			close(startup_pipe);
1988			startup_pipe = REEXEC_STARTUP_PIPE_FD;
1989		}
1990
1991		dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1992		close(config_s[1]);
1993
1994		execv(rexec_argv[0], rexec_argv);
1995
1996		/* Reexec has failed, fall back and continue */
1997		error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1998		recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1999		log_init(__progname, options.log_level,
2000		    options.log_facility, log_stderr);
2001
2002		/* Clean up fds */
2003		close(REEXEC_CONFIG_PASS_FD);
2004		newsock = sock_out = sock_in = dup(STDIN_FILENO);
2005		if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2006			dup2(fd, STDIN_FILENO);
2007			dup2(fd, STDOUT_FILENO);
2008			if (fd > STDERR_FILENO)
2009				close(fd);
2010		}
2011		debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2012		    sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2013	}
2014
2015	/* Executed child processes don't need these. */
2016	fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2017	fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2018
2019	/*
2020	 * Disable the key regeneration alarm.  We will not regenerate the
2021	 * key since we are no longer in a position to give it to anyone. We
2022	 * will not restart on SIGHUP since it no longer makes sense.
2023	 */
2024	alarm(0);
2025	signal(SIGALRM, SIG_DFL);
2026	signal(SIGHUP, SIG_DFL);
2027	signal(SIGTERM, SIG_DFL);
2028	signal(SIGQUIT, SIG_DFL);
2029	signal(SIGCHLD, SIG_DFL);
2030	signal(SIGINT, SIG_DFL);
2031
2032#ifdef __FreeBSD__
2033	/*
2034	 * Initialize the resolver.  This may not happen automatically
2035	 * before privsep chroot().
2036	 */
2037	if ((_res.options & RES_INIT) == 0) {
2038		debug("res_init()");
2039		res_init();
2040	}
2041#ifdef GSSAPI
2042	/*
2043	 * Force GSS-API to parse its configuration and load any
2044	 * mechanism plugins.
2045	 */
2046	{
2047		gss_OID_set mechs;
2048		OM_uint32 minor_status;
2049		gss_indicate_mechs(&minor_status, &mechs);
2050		gss_release_oid_set(&minor_status, &mechs);
2051	}
2052#endif
2053#endif
2054
2055	/*
2056	 * Register our connection.  This turns encryption off because we do
2057	 * not have a key.
2058	 */
2059	packet_set_connection(sock_in, sock_out);
2060	packet_set_server();
2061
2062	/* Set SO_KEEPALIVE if requested. */
2063	if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
2064	    setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
2065		error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2066
2067	if ((remote_port = get_remote_port()) < 0) {
2068		debug("get_remote_port failed");
2069		cleanup_exit(255);
2070	}
2071
2072	/*
2073	 * We use get_canonical_hostname with usedns = 0 instead of
2074	 * get_remote_ipaddr here so IP options will be checked.
2075	 */
2076	(void) get_canonical_hostname(0);
2077	/*
2078	 * The rest of the code depends on the fact that
2079	 * get_remote_ipaddr() caches the remote ip, even if
2080	 * the socket goes away.
2081	 */
2082	remote_ip = get_remote_ipaddr();
2083
2084#ifdef SSH_AUDIT_EVENTS
2085	audit_connection_from(remote_ip, remote_port);
2086#endif
2087#ifdef LIBWRAP
2088	allow_severity = options.log_facility|LOG_INFO;
2089	deny_severity = options.log_facility|LOG_WARNING;
2090	/* Check whether logins are denied from this host. */
2091	if (packet_connection_is_on_socket()) {
2092		struct request_info req;
2093
2094		request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
2095		fromhost(&req);
2096
2097		if (!hosts_access(&req)) {
2098			debug("Connection refused by tcp wrapper");
2099			refuse(&req);
2100			/* NOTREACHED */
2101			fatal("libwrap refuse returns");
2102		}
2103	}
2104#endif /* LIBWRAP */
2105
2106	/* Log the connection. */
2107	verbose("Connection from %s port %d on %s port %d",
2108	    remote_ip, remote_port,
2109	    get_local_ipaddr(sock_in), get_local_port());
2110
2111	/* Set HPN options for the child. */
2112	channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size);
2113
2114	/*
2115	 * We don't want to listen forever unless the other side
2116	 * successfully authenticates itself.  So we set up an alarm which is
2117	 * cleared after successful authentication.  A limit of zero
2118	 * indicates no limit. Note that we don't set the alarm in debugging
2119	 * mode; it is just annoying to have the server exit just when you
2120	 * are about to discover the bug.
2121	 */
2122	signal(SIGALRM, grace_alarm_handler);
2123	if (!debug_flag)
2124		alarm(options.login_grace_time);
2125
2126	sshd_exchange_identification(sock_in, sock_out);
2127
2128	/* In inetd mode, generate ephemeral key only for proto 1 connections */
2129	if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
2130		generate_ephemeral_server_key();
2131
2132	packet_set_nonblocking();
2133
2134	/* allocate authentication context */
2135	authctxt = xcalloc(1, sizeof(*authctxt));
2136
2137	authctxt->loginmsg = &loginmsg;
2138
2139	/* XXX global for cleanup, access from other modules */
2140	the_authctxt = authctxt;
2141
2142	/* prepare buffer to collect messages to display to user after login */
2143	buffer_init(&loginmsg);
2144	auth_debug_reset();
2145
2146	if (use_privsep) {
2147		if (privsep_preauth(authctxt) == 1)
2148			goto authenticated;
2149	} else if (compat20 && have_agent)
2150		auth_conn = ssh_get_authentication_connection();
2151
2152	/* perform the key exchange */
2153	/* authenticate user and start session */
2154	if (compat20) {
2155		do_ssh2_kex();
2156		do_authentication2(authctxt);
2157	} else {
2158		do_ssh1_kex();
2159		do_authentication(authctxt);
2160	}
2161	/*
2162	 * If we use privilege separation, the unprivileged child transfers
2163	 * the current keystate and exits
2164	 */
2165	if (use_privsep) {
2166		mm_send_keystate(pmonitor);
2167		exit(0);
2168	}
2169
2170 authenticated:
2171	/*
2172	 * Cancel the alarm we set to limit the time taken for
2173	 * authentication.
2174	 */
2175	alarm(0);
2176	signal(SIGALRM, SIG_DFL);
2177	authctxt->authenticated = 1;
2178	if (startup_pipe != -1) {
2179		close(startup_pipe);
2180		startup_pipe = -1;
2181	}
2182
2183#ifdef SSH_AUDIT_EVENTS
2184	audit_event(SSH_AUTH_SUCCESS);
2185#endif
2186
2187#ifdef GSSAPI
2188	if (options.gss_authentication) {
2189		temporarily_use_uid(authctxt->pw);
2190		ssh_gssapi_storecreds();
2191		restore_uid();
2192	}
2193#endif
2194#ifdef USE_PAM
2195	if (options.use_pam) {
2196		do_pam_setcred(1);
2197		do_pam_session();
2198	}
2199#endif
2200
2201	/*
2202	 * In privilege separation, we fork another child and prepare
2203	 * file descriptor passing.
2204	 */
2205	if (use_privsep) {
2206		privsep_postauth(authctxt);
2207		/* the monitor process [priv] will not return */
2208		if (!compat20)
2209			destroy_sensitive_data();
2210	}
2211
2212	packet_set_timeout(options.client_alive_interval,
2213	    options.client_alive_count_max);
2214
2215	/* Start session. */
2216	do_authenticated(authctxt);
2217
2218	/* The connection has been terminated. */
2219	packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2220	packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2221	verbose("Transferred: sent %llu, received %llu bytes",
2222	    (unsigned long long)obytes, (unsigned long long)ibytes);
2223
2224	verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2225
2226#ifdef USE_PAM
2227	if (options.use_pam)
2228		finish_pam();
2229#endif /* USE_PAM */
2230
2231#ifdef SSH_AUDIT_EVENTS
2232	PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2233#endif
2234
2235	packet_close();
2236
2237	if (use_privsep)
2238		mm_terminate();
2239
2240	exit(0);
2241}
2242
2243/*
2244 * Decrypt session_key_int using our private server key and private host key
2245 * (key with larger modulus first).
2246 */
2247int
2248ssh1_session_key(BIGNUM *session_key_int)
2249{
2250	int rsafail = 0;
2251
2252	if (BN_cmp(sensitive_data.server_key->rsa->n,
2253	    sensitive_data.ssh1_host_key->rsa->n) > 0) {
2254		/* Server key has bigger modulus. */
2255		if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2256		    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2257		    SSH_KEY_BITS_RESERVED) {
2258			fatal("do_connection: %s: "
2259			    "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2260			    get_remote_ipaddr(),
2261			    BN_num_bits(sensitive_data.server_key->rsa->n),
2262			    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2263			    SSH_KEY_BITS_RESERVED);
2264		}
2265		if (rsa_private_decrypt(session_key_int, session_key_int,
2266		    sensitive_data.server_key->rsa) <= 0)
2267			rsafail++;
2268		if (rsa_private_decrypt(session_key_int, session_key_int,
2269		    sensitive_data.ssh1_host_key->rsa) <= 0)
2270			rsafail++;
2271	} else {
2272		/* Host key has bigger modulus (or they are equal). */
2273		if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2274		    BN_num_bits(sensitive_data.server_key->rsa->n) +
2275		    SSH_KEY_BITS_RESERVED) {
2276			fatal("do_connection: %s: "
2277			    "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2278			    get_remote_ipaddr(),
2279			    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2280			    BN_num_bits(sensitive_data.server_key->rsa->n),
2281			    SSH_KEY_BITS_RESERVED);
2282		}
2283		if (rsa_private_decrypt(session_key_int, session_key_int,
2284		    sensitive_data.ssh1_host_key->rsa) < 0)
2285			rsafail++;
2286		if (rsa_private_decrypt(session_key_int, session_key_int,
2287		    sensitive_data.server_key->rsa) < 0)
2288			rsafail++;
2289	}
2290	return (rsafail);
2291}
2292/*
2293 * SSH1 key exchange
2294 */
2295static void
2296do_ssh1_kex(void)
2297{
2298	int i, len;
2299	int rsafail = 0;
2300	BIGNUM *session_key_int;
2301	u_char session_key[SSH_SESSION_KEY_LENGTH];
2302	u_char cookie[8];
2303	u_int cipher_type, auth_mask, protocol_flags;
2304
2305	/*
2306	 * Generate check bytes that the client must send back in the user
2307	 * packet in order for it to be accepted; this is used to defy ip
2308	 * spoofing attacks.  Note that this only works against somebody
2309	 * doing IP spoofing from a remote machine; any machine on the local
2310	 * network can still see outgoing packets and catch the random
2311	 * cookie.  This only affects rhosts authentication, and this is one
2312	 * of the reasons why it is inherently insecure.
2313	 */
2314	arc4random_buf(cookie, sizeof(cookie));
2315
2316	/*
2317	 * Send our public key.  We include in the packet 64 bits of random
2318	 * data that must be matched in the reply in order to prevent IP
2319	 * spoofing.
2320	 */
2321	packet_start(SSH_SMSG_PUBLIC_KEY);
2322	for (i = 0; i < 8; i++)
2323		packet_put_char(cookie[i]);
2324
2325	/* Store our public server RSA key. */
2326	packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2327	packet_put_bignum(sensitive_data.server_key->rsa->e);
2328	packet_put_bignum(sensitive_data.server_key->rsa->n);
2329
2330	/* Store our public host RSA key. */
2331	packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2332	packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2333	packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2334
2335	/* Put protocol flags. */
2336	packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2337
2338	/* Declare which ciphers we support. */
2339	packet_put_int(cipher_mask_ssh1(0));
2340
2341	/* Declare supported authentication types. */
2342	auth_mask = 0;
2343	if (options.rhosts_rsa_authentication)
2344		auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2345	if (options.rsa_authentication)
2346		auth_mask |= 1 << SSH_AUTH_RSA;
2347	if (options.challenge_response_authentication == 1)
2348		auth_mask |= 1 << SSH_AUTH_TIS;
2349	if (options.password_authentication)
2350		auth_mask |= 1 << SSH_AUTH_PASSWORD;
2351	packet_put_int(auth_mask);
2352
2353	/* Send the packet and wait for it to be sent. */
2354	packet_send();
2355	packet_write_wait();
2356
2357	debug("Sent %d bit server key and %d bit host key.",
2358	    BN_num_bits(sensitive_data.server_key->rsa->n),
2359	    BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2360
2361	/* Read clients reply (cipher type and session key). */
2362	packet_read_expect(SSH_CMSG_SESSION_KEY);
2363
2364	/* Get cipher type and check whether we accept this. */
2365	cipher_type = packet_get_char();
2366
2367	if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2368		packet_disconnect("Warning: client selects unsupported cipher.");
2369
2370	/* Get check bytes from the packet.  These must match those we
2371	   sent earlier with the public key packet. */
2372	for (i = 0; i < 8; i++)
2373		if (cookie[i] != packet_get_char())
2374			packet_disconnect("IP Spoofing check bytes do not match.");
2375
2376	debug("Encryption type: %.200s", cipher_name(cipher_type));
2377
2378	/* Get the encrypted integer. */
2379	if ((session_key_int = BN_new()) == NULL)
2380		fatal("do_ssh1_kex: BN_new failed");
2381	packet_get_bignum(session_key_int);
2382
2383	protocol_flags = packet_get_int();
2384	packet_set_protocol_flags(protocol_flags);
2385	packet_check_eom();
2386
2387	/* Decrypt session_key_int using host/server keys */
2388	rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2389
2390	/*
2391	 * Extract session key from the decrypted integer.  The key is in the
2392	 * least significant 256 bits of the integer; the first byte of the
2393	 * key is in the highest bits.
2394	 */
2395	if (!rsafail) {
2396		(void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2397		len = BN_num_bytes(session_key_int);
2398		if (len < 0 || (u_int)len > sizeof(session_key)) {
2399			error("do_ssh1_kex: bad session key len from %s: "
2400			    "session_key_int %d > sizeof(session_key) %lu",
2401			    get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2402			rsafail++;
2403		} else {
2404			memset(session_key, 0, sizeof(session_key));
2405			BN_bn2bin(session_key_int,
2406			    session_key + sizeof(session_key) - len);
2407
2408			derive_ssh1_session_id(
2409			    sensitive_data.ssh1_host_key->rsa->n,
2410			    sensitive_data.server_key->rsa->n,
2411			    cookie, session_id);
2412			/*
2413			 * Xor the first 16 bytes of the session key with the
2414			 * session id.
2415			 */
2416			for (i = 0; i < 16; i++)
2417				session_key[i] ^= session_id[i];
2418		}
2419	}
2420	if (rsafail) {
2421		int bytes = BN_num_bytes(session_key_int);
2422		u_char *buf = xmalloc(bytes);
2423		MD5_CTX md;
2424
2425		logit("do_connection: generating a fake encryption key");
2426		BN_bn2bin(session_key_int, buf);
2427		MD5_Init(&md);
2428		MD5_Update(&md, buf, bytes);
2429		MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2430		MD5_Final(session_key, &md);
2431		MD5_Init(&md);
2432		MD5_Update(&md, session_key, 16);
2433		MD5_Update(&md, buf, bytes);
2434		MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2435		MD5_Final(session_key + 16, &md);
2436		memset(buf, 0, bytes);
2437		free(buf);
2438		for (i = 0; i < 16; i++)
2439			session_id[i] = session_key[i] ^ session_key[i + 16];
2440	}
2441	/* Destroy the private and public keys. No longer. */
2442	destroy_sensitive_data();
2443
2444	if (use_privsep)
2445		mm_ssh1_session_id(session_id);
2446
2447	/* Destroy the decrypted integer.  It is no longer needed. */
2448	BN_clear_free(session_key_int);
2449
2450	/* Set the session key.  From this on all communications will be encrypted. */
2451	packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2452
2453	/* Destroy our copy of the session key.  It is no longer needed. */
2454	memset(session_key, 0, sizeof(session_key));
2455
2456	debug("Received session key; encryption turned on.");
2457
2458	/* Send an acknowledgment packet.  Note that this packet is sent encrypted. */
2459	packet_start(SSH_SMSG_SUCCESS);
2460	packet_send();
2461	packet_write_wait();
2462}
2463
2464void
2465sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen,
2466    u_char *data, u_int dlen)
2467{
2468	if (privkey) {
2469		if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0))
2470			fatal("%s: key_sign failed", __func__);
2471	} else if (use_privsep) {
2472		if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0)
2473			fatal("%s: pubkey_sign failed", __func__);
2474	} else {
2475		if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data,
2476		    dlen))
2477			fatal("%s: ssh_agent_sign failed", __func__);
2478	}
2479}
2480
2481/*
2482 * SSH2 key exchange: diffie-hellman-group1-sha1
2483 */
2484static void
2485do_ssh2_kex(void)
2486{
2487	Kex *kex;
2488
2489	if (options.ciphers != NULL) {
2490		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2491		myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2492#ifdef	NONE_CIPHER_ENABLED
2493	} else if (options.none_enabled == 1) {
2494		debug ("WARNING: None cipher enabled");
2495		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2496		myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE;
2497#endif
2498	}
2499	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2500	    compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2501	myproposal[PROPOSAL_ENC_ALGS_STOC] =
2502	    compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2503
2504	if (options.macs != NULL) {
2505		myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2506		myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2507	}
2508	if (options.compression == COMP_NONE) {
2509		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2510		myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2511	} else if (options.compression == COMP_DELAYED) {
2512		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2513		myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2514	}
2515	if (options.kex_algorithms != NULL)
2516		myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2517
2518	if (options.rekey_limit || options.rekey_interval)
2519		packet_set_rekey_limits((u_int32_t)options.rekey_limit,
2520		    (time_t)options.rekey_interval);
2521
2522	myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2523	    list_hostkey_types());
2524
2525	/* start key exchange */
2526	kex = kex_setup(myproposal);
2527	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2528	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2529	kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2530	kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2531	kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2532	kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2533	kex->server = 1;
2534	kex->client_version_string=client_version_string;
2535	kex->server_version_string=server_version_string;
2536	kex->load_host_public_key=&get_hostkey_public_by_type;
2537	kex->load_host_private_key=&get_hostkey_private_by_type;
2538	kex->host_key_index=&get_hostkey_index;
2539	kex->sign = sshd_hostkey_sign;
2540
2541	xxx_kex = kex;
2542
2543	dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2544
2545	session_id2 = kex->session_id;
2546	session_id2_len = kex->session_id_len;
2547
2548#ifdef DEBUG_KEXDH
2549	/* send 1st encrypted/maced/compressed message */
2550	packet_start(SSH2_MSG_IGNORE);
2551	packet_put_cstring("markus");
2552	packet_send();
2553	packet_write_wait();
2554#endif
2555	debug("KEX done");
2556}
2557
2558/* server specific fatal cleanup */
2559void
2560cleanup_exit(int i)
2561{
2562	if (the_authctxt) {
2563		do_cleanup(the_authctxt);
2564		if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) {
2565			debug("Killing privsep child %d", pmonitor->m_pid);
2566			if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2567			    errno != ESRCH)
2568				error("%s: kill(%d): %s", __func__,
2569				    pmonitor->m_pid, strerror(errno));
2570		}
2571	}
2572#ifdef SSH_AUDIT_EVENTS
2573	/* done after do_cleanup so it can cancel the PAM auth 'thread' */
2574	if (!use_privsep || mm_is_monitor())
2575		audit_event(SSH_CONNECTION_ABANDON);
2576#endif
2577	_exit(i);
2578}
2579