1 /* $OpenBSD: sshd.c,v 1.552 2020/03/13 04:01:57 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * 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 "sshpty.h"
92 #include "packet.h"
93 #include "log.h"
94 #include "sshbuf.h"
95 #include "misc.h"
96 #include "match.h"
97 #include "servconf.h"
98 #include "uidswap.h"
99 #include "compat.h"
100 #include "cipher.h"
101 #include "digest.h"
102 #include "sshkey.h"
103 #include "kex.h"
104 #include "myproposal.h"
105 #include "authfile.h"
106 #include "pathnames.h"
107 #include "atomicio.h"
108 #include "canohost.h"
109 #include "hostfile.h"
110 #include "auth.h"
111 #include "authfd.h"
112 #include "msg.h"
113 #include "dispatch.h"
114 #include "channels.h"
115 #include "session.h"
116 #include "monitor.h"
117 #ifdef GSSAPI
118 #include "ssh-gss.h"
119 #endif
120 #include "monitor_wrap.h"
121 #include "ssh-sandbox.h"
122 #include "auth-options.h"
123 #include "version.h"
124 #include "ssherr.h"
125 #include "sk-api.h"
126
127 /* Re-exec fds */
128 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
129 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
130 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
131 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
132
133 extern char *__progname;
134
135 /* Server configuration options. */
136 ServerOptions options;
137
138 /* Name of the server configuration file. */
139 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
140
141 /*
142 * Debug mode flag. This can be set on the command line. If debug
143 * mode is enabled, extra debugging output will be sent to the system
144 * log, the daemon will not go to background, and will exit after processing
145 * the first connection.
146 */
147 int debug_flag = 0;
148
149 /*
150 * Indicating that the daemon should only test the configuration and keys.
151 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
152 * configuration, optionally using connection information provided by the
153 * "-C" flag.
154 */
155 static int test_flag = 0;
156
157 /* Flag indicating that the daemon is being started from inetd. */
158 static int inetd_flag = 0;
159
160 /* Flag indicating that sshd should not detach and become a daemon. */
161 static int no_daemon_flag = 0;
162
163 /* debug goes to stderr unless inetd_flag is set */
164 static int log_stderr = 0;
165
166 /* Saved arguments to main(). */
167 static char **saved_argv;
168 static int saved_argc;
169
170 /* re-exec */
171 static int rexeced_flag = 0;
172 static int rexec_flag = 1;
173 static int rexec_argc = 0;
174 static char **rexec_argv;
175
176 /*
177 * The sockets that the server is listening; this is used in the SIGHUP
178 * signal handler.
179 */
180 #define MAX_LISTEN_SOCKS 16
181 static int listen_socks[MAX_LISTEN_SOCKS];
182 static int num_listen_socks = 0;
183
184 /* Daemon's agent connection */
185 int auth_sock = -1;
186 static int have_agent = 0;
187
188 /*
189 * Any really sensitive data in the application is contained in this
190 * structure. The idea is that this structure could be locked into memory so
191 * that the pages do not get written into swap. However, there are some
192 * problems. The private key contains BIGNUMs, and we do not (in principle)
193 * have access to the internals of them, and locking just the structure is
194 * not very useful. Currently, memory locking is not implemented.
195 */
196 struct {
197 struct sshkey **host_keys; /* all private host keys */
198 struct sshkey **host_pubkeys; /* all public host keys */
199 struct sshkey **host_certificates; /* all public host certificates */
200 int have_ssh2_key;
201 } sensitive_data;
202
203 /* This is set to true when a signal is received. */
204 static volatile sig_atomic_t received_sighup = 0;
205 static volatile sig_atomic_t received_sigterm = 0;
206
207 /* session identifier, used by RSA-auth */
208 u_char session_id[16];
209
210 /* same for ssh2 */
211 u_char *session_id2 = NULL;
212 u_int session_id2_len = 0;
213
214 /* record remote hostname or ip */
215 u_int utmp_len = HOST_NAME_MAX+1;
216
217 /*
218 * startup_pipes/flags are used for tracking children of the listening sshd
219 * process early in their lifespans. This tracking is needed for three things:
220 *
221 * 1) Implementing the MaxStartups limit of concurrent unauthenticated
222 * connections.
223 * 2) Avoiding a race condition for SIGHUP processing, where child processes
224 * may have listen_socks open that could collide with main listener process
225 * after it restarts.
226 * 3) Ensuring that rexec'd sshd processes have received their initial state
227 * from the parent listen process before handling SIGHUP.
228 *
229 * Child processes signal that they have completed closure of the listen_socks
230 * and (if applicable) received their rexec state by sending a char over their
231 * sock. Child processes signal that authentication has completed by closing
232 * the sock (or by exiting).
233 */
234 static int *startup_pipes = NULL;
235 static int *startup_flags = NULL; /* Indicates child closed listener */
236 static int startup_pipe = -1; /* in child */
237
238 /* variables used for privilege separation */
239 int use_privsep = -1;
240 struct monitor *pmonitor = NULL;
241 int privsep_is_preauth = 1;
242 static int privsep_chroot = 1;
243
244 /* global connection state and authentication contexts */
245 Authctxt *the_authctxt = NULL;
246 struct ssh *the_active_state;
247
248 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
249 struct sshauthopt *auth_opts = NULL;
250
251 /* sshd_config buffer */
252 struct sshbuf *cfg;
253
254 /* Included files from the configuration file */
255 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
256
257 /* message to be displayed after login */
258 struct sshbuf *loginmsg;
259
260 /* Unprivileged user */
261 struct passwd *privsep_pw = NULL;
262
263 /* Prototypes for various functions defined later in this file. */
264 void destroy_sensitive_data(void);
265 void demote_sensitive_data(void);
266 static void do_ssh2_kex(struct ssh *);
267
268 static char *listener_proctitle;
269
270 /*
271 * Close all listening sockets
272 */
273 static void
close_listen_socks(void)274 close_listen_socks(void)
275 {
276 int i;
277
278 for (i = 0; i < num_listen_socks; i++)
279 close(listen_socks[i]);
280 num_listen_socks = -1;
281 }
282
283 static void
close_startup_pipes(void)284 close_startup_pipes(void)
285 {
286 int i;
287
288 if (startup_pipes)
289 for (i = 0; i < options.max_startups; i++)
290 if (startup_pipes[i] != -1)
291 close(startup_pipes[i]);
292 }
293
294 /*
295 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
296 * the effect is to reread the configuration file (and to regenerate
297 * the server key).
298 */
299
300 /*ARGSUSED*/
301 static void
sighup_handler(int sig)302 sighup_handler(int sig)
303 {
304 received_sighup = 1;
305 }
306
307 /*
308 * Called from the main program after receiving SIGHUP.
309 * Restarts the server.
310 */
311 static void
sighup_restart(void)312 sighup_restart(void)
313 {
314 logit("Received SIGHUP; restarting.");
315 if (options.pid_file != NULL)
316 unlink(options.pid_file);
317 platform_pre_restart();
318 close_listen_socks();
319 close_startup_pipes();
320 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
321 execv(saved_argv[0], saved_argv);
322 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
323 strerror(errno));
324 exit(1);
325 }
326
327 /*
328 * Generic signal handler for terminating signals in the master daemon.
329 */
330 /*ARGSUSED*/
331 static void
sigterm_handler(int sig)332 sigterm_handler(int sig)
333 {
334 received_sigterm = sig;
335 }
336
337 /*
338 * SIGCHLD handler. This is called whenever a child dies. This will then
339 * reap any zombies left by exited children.
340 */
341 /*ARGSUSED*/
342 static void
main_sigchld_handler(int sig)343 main_sigchld_handler(int sig)
344 {
345 int save_errno = errno;
346 pid_t pid;
347 int status;
348
349 debug("main_sigchld_handler: %s", strsignal(sig));
350
351 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
352 (pid == -1 && errno == EINTR))
353 ;
354 errno = save_errno;
355 }
356
357 /*
358 * Signal handler for the alarm after the login grace period has expired.
359 */
360 /*ARGSUSED*/
361 static void
grace_alarm_handler(int sig)362 grace_alarm_handler(int sig)
363 {
364 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
365 kill(pmonitor->m_pid, SIGALRM);
366
367 /*
368 * Try to kill any processes that we have spawned, E.g. authorized
369 * keys command helpers.
370 */
371 if (getpgid(0) == getpid()) {
372 ssh_signal(SIGTERM, SIG_IGN);
373 kill(0, SIGTERM);
374 }
375
376 /* XXX pre-format ipaddr/port so we don't need to access active_state */
377 /* Log error and exit. */
378 sigdie("Timeout before authentication for %s port %d",
379 ssh_remote_ipaddr(the_active_state),
380 ssh_remote_port(the_active_state));
381 }
382
383 /* Destroy the host and server keys. They will no longer be needed. */
384 void
destroy_sensitive_data(void)385 destroy_sensitive_data(void)
386 {
387 u_int i;
388
389 for (i = 0; i < options.num_host_key_files; i++) {
390 if (sensitive_data.host_keys[i]) {
391 sshkey_free(sensitive_data.host_keys[i]);
392 sensitive_data.host_keys[i] = NULL;
393 }
394 if (sensitive_data.host_certificates[i]) {
395 sshkey_free(sensitive_data.host_certificates[i]);
396 sensitive_data.host_certificates[i] = NULL;
397 }
398 }
399 }
400
401 /* Demote private to public keys for network child */
402 void
demote_sensitive_data(void)403 demote_sensitive_data(void)
404 {
405 struct sshkey *tmp;
406 u_int i;
407 int r;
408
409 for (i = 0; i < options.num_host_key_files; i++) {
410 if (sensitive_data.host_keys[i]) {
411 if ((r = sshkey_from_private(
412 sensitive_data.host_keys[i], &tmp)) != 0)
413 fatal("could not demote host %s key: %s",
414 sshkey_type(sensitive_data.host_keys[i]),
415 ssh_err(r));
416 sshkey_free(sensitive_data.host_keys[i]);
417 sensitive_data.host_keys[i] = tmp;
418 }
419 /* Certs do not need demotion */
420 }
421 }
422
423 static void
reseed_prngs(void)424 reseed_prngs(void)
425 {
426 u_int32_t rnd[256];
427
428 #ifdef WITH_OPENSSL
429 RAND_poll();
430 #endif
431 arc4random_stir(); /* noop on recent arc4random() implementations */
432 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
433
434 #ifdef WITH_OPENSSL
435 RAND_seed(rnd, sizeof(rnd));
436 /* give libcrypto a chance to notice the PID change */
437 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
438 fatal("%s: RAND_bytes failed", __func__);
439 #endif
440
441 explicit_bzero(rnd, sizeof(rnd));
442 }
443
444 static void
privsep_preauth_child(void)445 privsep_preauth_child(void)
446 {
447 gid_t gidset[1];
448
449 /* Enable challenge-response authentication for privilege separation */
450 privsep_challenge_enable();
451
452 #ifdef GSSAPI
453 /* Cache supported mechanism OIDs for later use */
454 ssh_gssapi_prepare_supported_oids();
455 #endif
456
457 reseed_prngs();
458
459 /* Demote the private keys to public keys. */
460 demote_sensitive_data();
461
462 /* Demote the child */
463 if (privsep_chroot) {
464 /* Change our root directory */
465 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
466 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
467 strerror(errno));
468 if (chdir("/") == -1)
469 fatal("chdir(\"/\"): %s", strerror(errno));
470
471 /* Drop our privileges */
472 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
473 (u_int)privsep_pw->pw_gid);
474 gidset[0] = privsep_pw->pw_gid;
475 if (setgroups(1, gidset) == -1)
476 fatal("setgroups: %.100s", strerror(errno));
477 permanently_set_uid(privsep_pw);
478 }
479 }
480
481 static int
privsep_preauth(struct ssh * ssh)482 privsep_preauth(struct ssh *ssh)
483 {
484 int status, r;
485 pid_t pid;
486 struct ssh_sandbox *box = NULL;
487
488 /* Set up unprivileged child process to deal with network data */
489 pmonitor = monitor_init();
490 /* Store a pointer to the kex for later rekeying */
491 pmonitor->m_pkex = &ssh->kex;
492
493 if (use_privsep == PRIVSEP_ON)
494 box = ssh_sandbox_init(pmonitor);
495 pid = fork();
496 if (pid == -1) {
497 fatal("fork of unprivileged child failed");
498 } else if (pid != 0) {
499 debug2("Network child is on pid %ld", (long)pid);
500
501 pmonitor->m_pid = pid;
502 if (have_agent) {
503 r = ssh_get_authentication_socket(&auth_sock);
504 if (r != 0) {
505 error("Could not get agent socket: %s",
506 ssh_err(r));
507 have_agent = 0;
508 }
509 }
510 if (box != NULL)
511 ssh_sandbox_parent_preauth(box, pid);
512 monitor_child_preauth(ssh, pmonitor);
513
514 /* Wait for the child's exit status */
515 while (waitpid(pid, &status, 0) == -1) {
516 if (errno == EINTR)
517 continue;
518 pmonitor->m_pid = -1;
519 fatal("%s: waitpid: %s", __func__, strerror(errno));
520 }
521 privsep_is_preauth = 0;
522 pmonitor->m_pid = -1;
523 if (WIFEXITED(status)) {
524 if (WEXITSTATUS(status) != 0)
525 fatal("%s: preauth child exited with status %d",
526 __func__, WEXITSTATUS(status));
527 } else if (WIFSIGNALED(status))
528 fatal("%s: preauth child terminated by signal %d",
529 __func__, WTERMSIG(status));
530 if (box != NULL)
531 ssh_sandbox_parent_finish(box);
532 return 1;
533 } else {
534 /* child */
535 close(pmonitor->m_sendfd);
536 close(pmonitor->m_log_recvfd);
537
538 /* Arrange for logging to be sent to the monitor */
539 set_log_handler(mm_log_handler, pmonitor);
540
541 privsep_preauth_child();
542 setproctitle("%s", "[net]");
543 if (box != NULL)
544 ssh_sandbox_child(box);
545
546 return 0;
547 }
548 }
549
550 static void
privsep_postauth(struct ssh * ssh,Authctxt * authctxt)551 privsep_postauth(struct ssh *ssh, Authctxt *authctxt)
552 {
553 #ifdef DISABLE_FD_PASSING
554 if (1) {
555 #else
556 if (authctxt->pw->pw_uid == 0) {
557 #endif
558 /* File descriptor passing is broken or root login */
559 use_privsep = 0;
560 goto skip;
561 }
562
563 /* New socket pair */
564 monitor_reinit(pmonitor);
565
566 pmonitor->m_pid = fork();
567 if (pmonitor->m_pid == -1)
568 fatal("fork of unprivileged child failed");
569 else if (pmonitor->m_pid != 0) {
570 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
571 sshbuf_reset(loginmsg);
572 monitor_clear_keystate(ssh, pmonitor);
573 monitor_child_postauth(ssh, pmonitor);
574
575 /* NEVERREACHED */
576 exit(0);
577 }
578
579 /* child */
580
581 close(pmonitor->m_sendfd);
582 pmonitor->m_sendfd = -1;
583
584 /* Demote the private keys to public keys. */
585 demote_sensitive_data();
586
587 reseed_prngs();
588
589 /* Drop privileges */
590 do_setusercontext(authctxt->pw);
591
592 skip:
593 /* It is safe now to apply the key state */
594 monitor_apply_keystate(ssh, pmonitor);
595
596 /*
597 * Tell the packet layer that authentication was successful, since
598 * this information is not part of the key state.
599 */
600 ssh_packet_set_authenticated(ssh);
601 }
602
603 static void
604 append_hostkey_type(struct sshbuf *b, const char *s)
605 {
606 int r;
607
608 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
609 debug3("%s: %s key not permitted by HostkeyAlgorithms",
610 __func__, s);
611 return;
612 }
613 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
614 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
615 }
616
617 static char *
618 list_hostkey_types(void)
619 {
620 struct sshbuf *b;
621 struct sshkey *key;
622 char *ret;
623 u_int i;
624
625 if ((b = sshbuf_new()) == NULL)
626 fatal("%s: sshbuf_new failed", __func__);
627 for (i = 0; i < options.num_host_key_files; i++) {
628 key = sensitive_data.host_keys[i];
629 if (key == NULL)
630 key = sensitive_data.host_pubkeys[i];
631 if (key == NULL)
632 continue;
633 switch (key->type) {
634 case KEY_RSA:
635 /* for RSA we also support SHA2 signatures */
636 append_hostkey_type(b, "rsa-sha2-512");
637 append_hostkey_type(b, "rsa-sha2-256");
638 /* FALLTHROUGH */
639 case KEY_DSA:
640 case KEY_ECDSA:
641 case KEY_ED25519:
642 case KEY_ECDSA_SK:
643 case KEY_ED25519_SK:
644 case KEY_XMSS:
645 append_hostkey_type(b, sshkey_ssh_name(key));
646 break;
647 }
648 /* If the private key has a cert peer, then list that too */
649 key = sensitive_data.host_certificates[i];
650 if (key == NULL)
651 continue;
652 switch (key->type) {
653 case KEY_RSA_CERT:
654 /* for RSA we also support SHA2 signatures */
655 append_hostkey_type(b,
656 "rsa-sha2-512-cert-v01@openssh.com");
657 append_hostkey_type(b,
658 "rsa-sha2-256-cert-v01@openssh.com");
659 /* FALLTHROUGH */
660 case KEY_DSA_CERT:
661 case KEY_ECDSA_CERT:
662 case KEY_ED25519_CERT:
663 case KEY_ECDSA_SK_CERT:
664 case KEY_ED25519_SK_CERT:
665 case KEY_XMSS_CERT:
666 append_hostkey_type(b, sshkey_ssh_name(key));
667 break;
668 }
669 }
670 if ((ret = sshbuf_dup_string(b)) == NULL)
671 fatal("%s: sshbuf_dup_string failed", __func__);
672 sshbuf_free(b);
673 debug("%s: %s", __func__, ret);
674 return ret;
675 }
676
677 static struct sshkey *
678 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
679 {
680 u_int i;
681 struct sshkey *key;
682
683 for (i = 0; i < options.num_host_key_files; i++) {
684 switch (type) {
685 case KEY_RSA_CERT:
686 case KEY_DSA_CERT:
687 case KEY_ECDSA_CERT:
688 case KEY_ED25519_CERT:
689 case KEY_ECDSA_SK_CERT:
690 case KEY_ED25519_SK_CERT:
691 case KEY_XMSS_CERT:
692 key = sensitive_data.host_certificates[i];
693 break;
694 default:
695 key = sensitive_data.host_keys[i];
696 if (key == NULL && !need_private)
697 key = sensitive_data.host_pubkeys[i];
698 break;
699 }
700 if (key == NULL || key->type != type)
701 continue;
702 switch (type) {
703 case KEY_ECDSA:
704 case KEY_ECDSA_SK:
705 case KEY_ECDSA_CERT:
706 case KEY_ECDSA_SK_CERT:
707 if (key->ecdsa_nid != nid)
708 continue;
709 /* FALLTHROUGH */
710 default:
711 return need_private ?
712 sensitive_data.host_keys[i] : key;
713 }
714 }
715 return NULL;
716 }
717
718 struct sshkey *
719 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
720 {
721 return get_hostkey_by_type(type, nid, 0, ssh);
722 }
723
724 struct sshkey *
725 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
726 {
727 return get_hostkey_by_type(type, nid, 1, ssh);
728 }
729
730 struct sshkey *
731 get_hostkey_by_index(int ind)
732 {
733 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
734 return (NULL);
735 return (sensitive_data.host_keys[ind]);
736 }
737
738 struct sshkey *
739 get_hostkey_public_by_index(int ind, struct ssh *ssh)
740 {
741 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
742 return (NULL);
743 return (sensitive_data.host_pubkeys[ind]);
744 }
745
746 int
747 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
748 {
749 u_int i;
750
751 for (i = 0; i < options.num_host_key_files; i++) {
752 if (sshkey_is_cert(key)) {
753 if (key == sensitive_data.host_certificates[i] ||
754 (compare && sensitive_data.host_certificates[i] &&
755 sshkey_equal(key,
756 sensitive_data.host_certificates[i])))
757 return (i);
758 } else {
759 if (key == sensitive_data.host_keys[i] ||
760 (compare && sensitive_data.host_keys[i] &&
761 sshkey_equal(key, sensitive_data.host_keys[i])))
762 return (i);
763 if (key == sensitive_data.host_pubkeys[i] ||
764 (compare && sensitive_data.host_pubkeys[i] &&
765 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
766 return (i);
767 }
768 }
769 return (-1);
770 }
771
772 /* Inform the client of all hostkeys */
773 static void
774 notify_hostkeys(struct ssh *ssh)
775 {
776 struct sshbuf *buf;
777 struct sshkey *key;
778 u_int i, nkeys;
779 int r;
780 char *fp;
781
782 /* Some clients cannot cope with the hostkeys message, skip those. */
783 if (ssh->compat & SSH_BUG_HOSTKEYS)
784 return;
785
786 if ((buf = sshbuf_new()) == NULL)
787 fatal("%s: sshbuf_new", __func__);
788 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
789 key = get_hostkey_public_by_index(i, ssh);
790 if (key == NULL || key->type == KEY_UNSPEC ||
791 sshkey_is_cert(key))
792 continue;
793 fp = sshkey_fingerprint(key, options.fingerprint_hash,
794 SSH_FP_DEFAULT);
795 debug3("%s: key %d: %s %s", __func__, i,
796 sshkey_ssh_name(key), fp);
797 free(fp);
798 if (nkeys == 0) {
799 /*
800 * Start building the request when we find the
801 * first usable key.
802 */
803 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
804 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 ||
805 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */
806 sshpkt_fatal(ssh, r, "%s: start request", __func__);
807 }
808 /* Append the key to the request */
809 sshbuf_reset(buf);
810 if ((r = sshkey_putb(key, buf)) != 0)
811 fatal("%s: couldn't put hostkey %d: %s",
812 __func__, i, ssh_err(r));
813 if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
814 sshpkt_fatal(ssh, r, "%s: append key", __func__);
815 nkeys++;
816 }
817 debug3("%s: sent %u hostkeys", __func__, nkeys);
818 if (nkeys == 0)
819 fatal("%s: no hostkeys", __func__);
820 if ((r = sshpkt_send(ssh)) != 0)
821 sshpkt_fatal(ssh, r, "%s: send", __func__);
822 sshbuf_free(buf);
823 }
824
825 /*
826 * returns 1 if connection should be dropped, 0 otherwise.
827 * dropping starts at connection #max_startups_begin with a probability
828 * of (max_startups_rate/100). the probability increases linearly until
829 * all connections are dropped for startups > max_startups
830 */
831 static int
832 drop_connection(int startups)
833 {
834 int p, r;
835
836 if (startups < options.max_startups_begin)
837 return 0;
838 if (startups >= options.max_startups)
839 return 1;
840 if (options.max_startups_rate == 100)
841 return 1;
842
843 p = 100 - options.max_startups_rate;
844 p *= startups - options.max_startups_begin;
845 p /= options.max_startups - options.max_startups_begin;
846 p += options.max_startups_rate;
847 r = arc4random_uniform(100);
848
849 debug("drop_connection: p %d, r %d", p, r);
850 return (r < p) ? 1 : 0;
851 }
852
853 static void
854 usage(void)
855 {
856 fprintf(stderr, "%s, %s\n",
857 SSH_RELEASE,
858 #ifdef WITH_OPENSSL
859 OpenSSL_version(OPENSSL_VERSION)
860 #else
861 "without OpenSSL"
862 #endif
863 );
864 fprintf(stderr,
865 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
866 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
867 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
868 );
869 exit(1);
870 }
871
872 static void
873 send_rexec_state(int fd, struct sshbuf *conf)
874 {
875 struct sshbuf *m = NULL, *inc = NULL;
876 struct include_item *item = NULL;
877 int r;
878
879 debug3("%s: entering fd = %d config len %zu", __func__, fd,
880 sshbuf_len(conf));
881
882 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
883 fatal("%s: sshbuf_new failed", __func__);
884
885 /* pack includes into a string */
886 TAILQ_FOREACH(item, &includes, entry) {
887 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
888 (r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
889 (r = sshbuf_put_stringb(inc, item->contents)) != 0)
890 fatal("%s: buffer error: %s", __func__, ssh_err(r));
891 }
892
893 /*
894 * Protocol from reexec master to child:
895 * string configuration
896 * string included_files[] {
897 * string selector
898 * string filename
899 * string contents
900 * }
901 * string rng_seed (if required)
902 */
903 if ((r = sshbuf_put_stringb(m, conf)) != 0 ||
904 (r = sshbuf_put_stringb(m, inc)) != 0)
905 fatal("%s: buffer error: %s", __func__, ssh_err(r));
906 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
907 rexec_send_rng_seed(m);
908 #endif
909 if (ssh_msg_send(fd, 0, m) == -1)
910 fatal("%s: ssh_msg_send failed", __func__);
911
912 sshbuf_free(m);
913 sshbuf_free(inc);
914
915 debug3("%s: done", __func__);
916 }
917
918 static void
919 recv_rexec_state(int fd, struct sshbuf *conf)
920 {
921 struct sshbuf *m, *inc;
922 u_char *cp, ver;
923 size_t len;
924 int r;
925 struct include_item *item;
926
927 debug3("%s: entering fd = %d", __func__, fd);
928
929 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
930 fatal("%s: sshbuf_new failed", __func__);
931 if (ssh_msg_recv(fd, m) == -1)
932 fatal("%s: ssh_msg_recv failed", __func__);
933 if ((r = sshbuf_get_u8(m, &ver)) != 0)
934 fatal("%s: buffer error: %s", __func__, ssh_err(r));
935 if (ver != 0)
936 fatal("%s: rexec version mismatch", __func__);
937 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 ||
938 (r = sshbuf_get_stringb(m, inc)) != 0)
939 fatal("%s: buffer error: %s", __func__, ssh_err(r));
940
941 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
942 rexec_recv_rng_seed(m);
943 #endif
944
945 if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
946 fatal("%s: buffer error: %s", __func__, ssh_err(r));
947
948 while (sshbuf_len(inc) != 0) {
949 item = xcalloc(1, sizeof(*item));
950 if ((item->contents = sshbuf_new()) == NULL)
951 fatal("%s: sshbuf_new failed", __func__);
952 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
953 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
954 (r = sshbuf_get_stringb(inc, item->contents)) != 0)
955 fatal("%s: buffer error: %s", __func__, ssh_err(r));
956 TAILQ_INSERT_TAIL(&includes, item, entry);
957 }
958
959 free(cp);
960 sshbuf_free(m);
961
962 debug3("%s: done", __func__);
963 }
964
965 /* Accept a connection from inetd */
966 static void
967 server_accept_inetd(int *sock_in, int *sock_out)
968 {
969 int fd;
970
971 if (rexeced_flag) {
972 close(REEXEC_CONFIG_PASS_FD);
973 *sock_in = *sock_out = dup(STDIN_FILENO);
974 } else {
975 *sock_in = dup(STDIN_FILENO);
976 *sock_out = dup(STDOUT_FILENO);
977 }
978 /*
979 * We intentionally do not close the descriptors 0, 1, and 2
980 * as our code for setting the descriptors won't work if
981 * ttyfd happens to be one of those.
982 */
983 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
984 dup2(fd, STDIN_FILENO);
985 dup2(fd, STDOUT_FILENO);
986 if (!log_stderr)
987 dup2(fd, STDERR_FILENO);
988 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
989 close(fd);
990 }
991 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
992 }
993
994 /*
995 * Listen for TCP connections
996 */
997 static void
998 listen_on_addrs(struct listenaddr *la)
999 {
1000 int ret, listen_sock;
1001 struct addrinfo *ai;
1002 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1003
1004 for (ai = la->addrs; ai; ai = ai->ai_next) {
1005 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1006 continue;
1007 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1008 fatal("Too many listen sockets. "
1009 "Enlarge MAX_LISTEN_SOCKS");
1010 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1011 ntop, sizeof(ntop), strport, sizeof(strport),
1012 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1013 error("getnameinfo failed: %.100s",
1014 ssh_gai_strerror(ret));
1015 continue;
1016 }
1017 /* Create socket for listening. */
1018 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1019 ai->ai_protocol);
1020 if (listen_sock == -1) {
1021 /* kernel may not support ipv6 */
1022 verbose("socket: %.100s", strerror(errno));
1023 continue;
1024 }
1025 if (set_nonblock(listen_sock) == -1) {
1026 close(listen_sock);
1027 continue;
1028 }
1029 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1030 verbose("socket: CLOEXEC: %s", strerror(errno));
1031 close(listen_sock);
1032 continue;
1033 }
1034 /* Socket options */
1035 set_reuseaddr(listen_sock);
1036 if (la->rdomain != NULL &&
1037 set_rdomain(listen_sock, la->rdomain) == -1) {
1038 close(listen_sock);
1039 continue;
1040 }
1041
1042 /* Only communicate in IPv6 over AF_INET6 sockets. */
1043 if (ai->ai_family == AF_INET6)
1044 sock_set_v6only(listen_sock);
1045
1046 debug("Bind to port %s on %s.", strport, ntop);
1047
1048 /* Bind the socket to the desired port. */
1049 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) {
1050 error("Bind to port %s on %s failed: %.200s.",
1051 strport, ntop, strerror(errno));
1052 close(listen_sock);
1053 continue;
1054 }
1055 listen_socks[num_listen_socks] = listen_sock;
1056 num_listen_socks++;
1057
1058 /* Start listening on the port. */
1059 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1)
1060 fatal("listen on [%s]:%s: %.100s",
1061 ntop, strport, strerror(errno));
1062 logit("Server listening on %s port %s%s%s.",
1063 ntop, strport,
1064 la->rdomain == NULL ? "" : " rdomain ",
1065 la->rdomain == NULL ? "" : la->rdomain);
1066 }
1067 }
1068
1069 static void
1070 server_listen(void)
1071 {
1072 u_int i;
1073
1074 for (i = 0; i < options.num_listen_addrs; i++) {
1075 listen_on_addrs(&options.listen_addrs[i]);
1076 freeaddrinfo(options.listen_addrs[i].addrs);
1077 free(options.listen_addrs[i].rdomain);
1078 memset(&options.listen_addrs[i], 0,
1079 sizeof(options.listen_addrs[i]));
1080 }
1081 free(options.listen_addrs);
1082 options.listen_addrs = NULL;
1083 options.num_listen_addrs = 0;
1084
1085 if (!num_listen_socks)
1086 fatal("Cannot bind any address.");
1087 }
1088
1089 /*
1090 * The main TCP accept loop. Note that, for the non-debug case, returns
1091 * from this function are in a forked subprocess.
1092 */
1093 static void
1094 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1095 {
1096 fd_set *fdset;
1097 int i, j, ret, maxfd;
1098 int ostartups = -1, startups = 0, listening = 0, lameduck = 0;
1099 int startup_p[2] = { -1 , -1 };
1100 char c = 0;
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 child sshd processes */
1113 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1114 startup_flags = xcalloc(options.max_startups, sizeof(int));
1115 for (i = 0; i < options.max_startups; i++)
1116 startup_pipes[i] = -1;
1117
1118 /*
1119 * Stay listening for connections until the system crashes or
1120 * the daemon is killed with a signal.
1121 */
1122 for (;;) {
1123 if (ostartups != startups) {
1124 setproctitle("%s [listener] %d of %d-%d startups",
1125 listener_proctitle, startups,
1126 options.max_startups_begin, options.max_startups);
1127 ostartups = startups;
1128 }
1129 if (received_sighup) {
1130 if (!lameduck) {
1131 debug("Received SIGHUP; waiting for children");
1132 close_listen_socks();
1133 lameduck = 1;
1134 }
1135 if (listening <= 0)
1136 sighup_restart();
1137 }
1138 free(fdset);
1139 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1140 sizeof(fd_mask));
1141
1142 for (i = 0; i < num_listen_socks; i++)
1143 FD_SET(listen_socks[i], fdset);
1144 for (i = 0; i < options.max_startups; i++)
1145 if (startup_pipes[i] != -1)
1146 FD_SET(startup_pipes[i], fdset);
1147
1148 /* Wait in select until there is a connection. */
1149 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1150 if (ret == -1 && errno != EINTR)
1151 error("select: %.100s", strerror(errno));
1152 if (received_sigterm) {
1153 logit("Received signal %d; terminating.",
1154 (int) received_sigterm);
1155 close_listen_socks();
1156 if (options.pid_file != NULL)
1157 unlink(options.pid_file);
1158 exit(received_sigterm == SIGTERM ? 0 : 255);
1159 }
1160 if (ret == -1)
1161 continue;
1162
1163 for (i = 0; i < options.max_startups; i++) {
1164 if (startup_pipes[i] == -1 ||
1165 !FD_ISSET(startup_pipes[i], fdset))
1166 continue;
1167 switch (read(startup_pipes[i], &c, sizeof(c))) {
1168 case -1:
1169 if (errno == EINTR || errno == EAGAIN)
1170 continue;
1171 if (errno != EPIPE) {
1172 error("%s: startup pipe %d (fd=%d): "
1173 "read %s", __func__, i,
1174 startup_pipes[i], strerror(errno));
1175 }
1176 /* FALLTHROUGH */
1177 case 0:
1178 /* child exited or completed auth */
1179 close(startup_pipes[i]);
1180 startup_pipes[i] = -1;
1181 startups--;
1182 if (startup_flags[i])
1183 listening--;
1184 break;
1185 case 1:
1186 /* child has finished preliminaries */
1187 if (startup_flags[i]) {
1188 listening--;
1189 startup_flags[i] = 0;
1190 }
1191 break;
1192 }
1193 }
1194 for (i = 0; i < num_listen_socks; i++) {
1195 if (!FD_ISSET(listen_socks[i], fdset))
1196 continue;
1197 fromlen = sizeof(from);
1198 *newsock = accept(listen_socks[i],
1199 (struct sockaddr *)&from, &fromlen);
1200 if (*newsock == -1) {
1201 if (errno != EINTR && errno != EWOULDBLOCK &&
1202 errno != ECONNABORTED && errno != EAGAIN)
1203 error("accept: %.100s",
1204 strerror(errno));
1205 if (errno == EMFILE || errno == ENFILE)
1206 usleep(100 * 1000);
1207 continue;
1208 }
1209 if (unset_nonblock(*newsock) == -1) {
1210 close(*newsock);
1211 continue;
1212 }
1213 if (drop_connection(startups) == 1) {
1214 char *laddr = get_local_ipaddr(*newsock);
1215 char *raddr = get_peer_ipaddr(*newsock);
1216 char msg[] = "Exceeded MaxStartups\r\n";
1217
1218 verbose("drop connection #%d from [%s]:%d "
1219 "on [%s]:%d past MaxStartups", startups,
1220 raddr, get_peer_port(*newsock),
1221 laddr, get_local_port(*newsock));
1222 free(laddr);
1223 free(raddr);
1224 /* best-effort notification to client */
1225 (void)write(*newsock, msg, strlen(msg));
1226 close(*newsock);
1227 continue;
1228 }
1229 if (pipe(startup_p) == -1) {
1230 close(*newsock);
1231 continue;
1232 }
1233
1234 if (rexec_flag && socketpair(AF_UNIX,
1235 SOCK_STREAM, 0, config_s) == -1) {
1236 error("reexec socketpair: %s",
1237 strerror(errno));
1238 close(*newsock);
1239 close(startup_p[0]);
1240 close(startup_p[1]);
1241 continue;
1242 }
1243
1244 for (j = 0; j < options.max_startups; j++)
1245 if (startup_pipes[j] == -1) {
1246 startup_pipes[j] = startup_p[0];
1247 if (maxfd < startup_p[0])
1248 maxfd = startup_p[0];
1249 startups++;
1250 startup_flags[j] = 1;
1251 break;
1252 }
1253
1254 /*
1255 * Got connection. Fork a child to handle it, unless
1256 * we are in debugging mode.
1257 */
1258 if (debug_flag) {
1259 /*
1260 * In debugging mode. Close the listening
1261 * socket, and start processing the
1262 * connection without forking.
1263 */
1264 debug("Server will not fork when running in debugging mode.");
1265 close_listen_socks();
1266 *sock_in = *newsock;
1267 *sock_out = *newsock;
1268 close(startup_p[0]);
1269 close(startup_p[1]);
1270 startup_pipe = -1;
1271 pid = getpid();
1272 if (rexec_flag) {
1273 send_rexec_state(config_s[0], cfg);
1274 close(config_s[0]);
1275 }
1276 return;
1277 }
1278
1279 /*
1280 * Normal production daemon. Fork, and have
1281 * the child process the connection. The
1282 * parent continues listening.
1283 */
1284 platform_pre_fork();
1285 listening++;
1286 if ((pid = fork()) == 0) {
1287 /*
1288 * Child. Close the listening and
1289 * max_startup sockets. Start using
1290 * the accepted socket. Reinitialize
1291 * logging (since our pid has changed).
1292 * We return from this function to handle
1293 * the connection.
1294 */
1295 platform_post_fork_child();
1296 startup_pipe = startup_p[1];
1297 close_startup_pipes();
1298 close_listen_socks();
1299 *sock_in = *newsock;
1300 *sock_out = *newsock;
1301 log_init(__progname,
1302 options.log_level,
1303 options.log_facility,
1304 log_stderr);
1305 if (rexec_flag)
1306 close(config_s[0]);
1307 else {
1308 /*
1309 * Signal parent that the preliminaries
1310 * for this child are complete. For the
1311 * re-exec case, this happens after the
1312 * child has received the rexec state
1313 * from the server.
1314 */
1315 (void)atomicio(vwrite, startup_pipe,
1316 "\0", 1);
1317 }
1318 return;
1319 }
1320
1321 /* Parent. Stay in the loop. */
1322 platform_post_fork_parent(pid);
1323 if (pid == -1)
1324 error("fork: %.100s", strerror(errno));
1325 else
1326 debug("Forked child %ld.", (long)pid);
1327
1328 close(startup_p[1]);
1329
1330 if (rexec_flag) {
1331 send_rexec_state(config_s[0], cfg);
1332 close(config_s[0]);
1333 close(config_s[1]);
1334 }
1335 close(*newsock);
1336
1337 /*
1338 * Ensure that our random state differs
1339 * from that of the child
1340 */
1341 arc4random_stir();
1342 arc4random_buf(rnd, sizeof(rnd));
1343 #ifdef WITH_OPENSSL
1344 RAND_seed(rnd, sizeof(rnd));
1345 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1346 fatal("%s: RAND_bytes failed", __func__);
1347 #endif
1348 explicit_bzero(rnd, sizeof(rnd));
1349 }
1350 }
1351 }
1352
1353 /*
1354 * If IP options are supported, make sure there are none (log and
1355 * return an error if any are found). Basically we are worried about
1356 * source routing; it can be used to pretend you are somebody
1357 * (ip-address) you are not. That itself may be "almost acceptable"
1358 * under certain circumstances, but rhosts authentication is useless
1359 * if source routing is accepted. Notice also that if we just dropped
1360 * source routing here, the other side could use IP spoofing to do
1361 * rest of the interaction and could still bypass security. So we
1362 * exit here if we detect any IP options.
1363 */
1364 static void
1365 check_ip_options(struct ssh *ssh)
1366 {
1367 #ifdef IP_OPTIONS
1368 int sock_in = ssh_packet_get_connection_in(ssh);
1369 struct sockaddr_storage from;
1370 u_char opts[200];
1371 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1372 char text[sizeof(opts) * 3 + 1];
1373
1374 memset(&from, 0, sizeof(from));
1375 if (getpeername(sock_in, (struct sockaddr *)&from,
1376 &fromlen) == -1)
1377 return;
1378 if (from.ss_family != AF_INET)
1379 return;
1380 /* XXX IPv6 options? */
1381
1382 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1383 &option_size) >= 0 && option_size != 0) {
1384 text[0] = '\0';
1385 for (i = 0; i < option_size; i++)
1386 snprintf(text + i*3, sizeof(text) - i*3,
1387 " %2.2x", opts[i]);
1388 fatal("Connection from %.100s port %d with IP opts: %.800s",
1389 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1390 }
1391 return;
1392 #endif /* IP_OPTIONS */
1393 }
1394
1395 /* Set the routing domain for this process */
1396 static void
1397 set_process_rdomain(struct ssh *ssh, const char *name)
1398 {
1399 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
1400 if (name == NULL)
1401 return; /* default */
1402
1403 if (strcmp(name, "%D") == 0) {
1404 /* "expands" to routing domain of connection */
1405 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1406 return;
1407 }
1408 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
1409 return sys_set_process_rdomain(name);
1410 #elif defined(__OpenBSD__)
1411 int rtable, ortable = getrtable();
1412 const char *errstr;
1413
1414 if (name == NULL)
1415 return; /* default */
1416
1417 if (strcmp(name, "%D") == 0) {
1418 /* "expands" to routing domain of connection */
1419 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1420 return;
1421 }
1422
1423 rtable = (int)strtonum(name, 0, 255, &errstr);
1424 if (errstr != NULL) /* Shouldn't happen */
1425 fatal("Invalid routing domain \"%s\": %s", name, errstr);
1426 if (rtable != ortable && setrtable(rtable) != 0)
1427 fatal("Unable to set routing domain %d: %s",
1428 rtable, strerror(errno));
1429 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
1430 #else /* defined(__OpenBSD__) */
1431 fatal("Unable to set routing domain: not supported in this platform");
1432 #endif
1433 }
1434
1435 static void
1436 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1437 struct sshkey *key)
1438 {
1439 static struct ssh_digest_ctx *ctx;
1440 u_char *hash;
1441 size_t len;
1442 struct sshbuf *buf;
1443 int r;
1444
1445 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1446 fatal("%s: ssh_digest_start", __func__);
1447 if (key == NULL) { /* finalize */
1448 /* add server config in case we are using agent for host keys */
1449 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1450 sshbuf_len(server_cfg)) != 0)
1451 fatal("%s: ssh_digest_update", __func__);
1452 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1453 hash = xmalloc(len);
1454 if (ssh_digest_final(ctx, hash, len) != 0)
1455 fatal("%s: ssh_digest_final", __func__);
1456 options.timing_secret = PEEK_U64(hash);
1457 freezero(hash, len);
1458 ssh_digest_free(ctx);
1459 ctx = NULL;
1460 return;
1461 }
1462 if ((buf = sshbuf_new()) == NULL)
1463 fatal("%s could not allocate buffer", __func__);
1464 if ((r = sshkey_private_serialize(key, buf)) != 0)
1465 fatal("sshkey_private_serialize: %s", ssh_err(r));
1466 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1467 fatal("%s: ssh_digest_update", __func__);
1468 sshbuf_reset(buf);
1469 sshbuf_free(buf);
1470 }
1471
1472 static char *
1473 prepare_proctitle(int ac, char **av)
1474 {
1475 char *ret = NULL;
1476 int i;
1477
1478 for (i = 0; i < ac; i++)
1479 xextendf(&ret, " ", "%s", av[i]);
1480 return ret;
1481 }
1482
1483 /*
1484 * Main program for the daemon.
1485 */
1486 int
1487 main(int ac, char **av)
1488 {
1489 struct ssh *ssh = NULL;
1490 extern char *optarg;
1491 extern int optind;
1492 int r, opt, on = 1, already_daemon, remote_port;
1493 int sock_in = -1, sock_out = -1, newsock = -1;
1494 const char *remote_ip, *rdomain;
1495 char *fp, *line, *laddr, *logfile = NULL;
1496 int config_s[2] = { -1 , -1 };
1497 u_int i, j;
1498 u_int64_t ibytes, obytes;
1499 mode_t new_umask;
1500 struct sshkey *key;
1501 struct sshkey *pubkey;
1502 int keytype;
1503 Authctxt *authctxt;
1504 struct connection_info *connection_info = NULL;
1505
1506 #ifdef HAVE_SECUREWARE
1507 (void)set_auth_parameters(ac, av);
1508 #endif
1509 __progname = ssh_get_progname(av[0]);
1510
1511 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1512 saved_argc = ac;
1513 rexec_argc = ac;
1514 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1515 for (i = 0; (int)i < ac; i++)
1516 saved_argv[i] = xstrdup(av[i]);
1517 saved_argv[i] = NULL;
1518
1519 #ifndef HAVE_SETPROCTITLE
1520 /* Prepare for later setproctitle emulation */
1521 compat_init_setproctitle(ac, av);
1522 av = saved_argv;
1523 #endif
1524
1525 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1526 debug("setgroups(): %.200s", strerror(errno));
1527
1528 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1529 sanitise_stdfd();
1530
1531 seed_rng();
1532
1533 /* Initialize configuration options to their default values. */
1534 initialize_server_options(&options);
1535
1536 /* Parse command-line arguments. */
1537 while ((opt = getopt(ac, av,
1538 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1539 switch (opt) {
1540 case '4':
1541 options.address_family = AF_INET;
1542 break;
1543 case '6':
1544 options.address_family = AF_INET6;
1545 break;
1546 case 'f':
1547 config_file_name = optarg;
1548 break;
1549 case 'c':
1550 servconf_add_hostcert("[command-line]", 0,
1551 &options, optarg);
1552 break;
1553 case 'd':
1554 if (debug_flag == 0) {
1555 debug_flag = 1;
1556 options.log_level = SYSLOG_LEVEL_DEBUG1;
1557 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1558 options.log_level++;
1559 break;
1560 case 'D':
1561 no_daemon_flag = 1;
1562 break;
1563 case 'E':
1564 logfile = optarg;
1565 /* FALLTHROUGH */
1566 case 'e':
1567 log_stderr = 1;
1568 break;
1569 case 'i':
1570 inetd_flag = 1;
1571 break;
1572 case 'r':
1573 rexec_flag = 0;
1574 break;
1575 case 'R':
1576 rexeced_flag = 1;
1577 inetd_flag = 1;
1578 break;
1579 case 'Q':
1580 /* ignored */
1581 break;
1582 case 'q':
1583 options.log_level = SYSLOG_LEVEL_QUIET;
1584 break;
1585 case 'b':
1586 /* protocol 1, ignored */
1587 break;
1588 case 'p':
1589 options.ports_from_cmdline = 1;
1590 if (options.num_ports >= MAX_PORTS) {
1591 fprintf(stderr, "too many ports.\n");
1592 exit(1);
1593 }
1594 options.ports[options.num_ports++] = a2port(optarg);
1595 if (options.ports[options.num_ports-1] <= 0) {
1596 fprintf(stderr, "Bad port number.\n");
1597 exit(1);
1598 }
1599 break;
1600 case 'g':
1601 if ((options.login_grace_time = convtime(optarg)) == -1) {
1602 fprintf(stderr, "Invalid login grace time.\n");
1603 exit(1);
1604 }
1605 break;
1606 case 'k':
1607 /* protocol 1, ignored */
1608 break;
1609 case 'h':
1610 servconf_add_hostkey("[command-line]", 0,
1611 &options, optarg, 1);
1612 break;
1613 case 't':
1614 test_flag = 1;
1615 break;
1616 case 'T':
1617 test_flag = 2;
1618 break;
1619 case 'C':
1620 connection_info = get_connection_info(ssh, 0, 0);
1621 if (parse_server_match_testspec(connection_info,
1622 optarg) == -1)
1623 exit(1);
1624 break;
1625 case 'u':
1626 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1627 if (utmp_len > HOST_NAME_MAX+1) {
1628 fprintf(stderr, "Invalid utmp length.\n");
1629 exit(1);
1630 }
1631 break;
1632 case 'o':
1633 line = xstrdup(optarg);
1634 if (process_server_config_line(&options, line,
1635 "command-line", 0, NULL, NULL, &includes) != 0)
1636 exit(1);
1637 free(line);
1638 break;
1639 case '?':
1640 default:
1641 usage();
1642 break;
1643 }
1644 }
1645 if (rexeced_flag || inetd_flag)
1646 rexec_flag = 0;
1647 if (!test_flag && rexec_flag && !path_absolute(av[0]))
1648 fatal("sshd re-exec requires execution with an absolute path");
1649 if (rexeced_flag)
1650 closefrom(REEXEC_MIN_FREE_FD);
1651 else
1652 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1653
1654 /* If requested, redirect the logs to the specified logfile. */
1655 if (logfile != NULL)
1656 log_redirect_stderr_to(logfile);
1657 /*
1658 * Force logging to stderr until we have loaded the private host
1659 * key (unless started from inetd)
1660 */
1661 log_init(__progname,
1662 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1663 SYSLOG_LEVEL_INFO : options.log_level,
1664 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1665 SYSLOG_FACILITY_AUTH : options.log_facility,
1666 log_stderr || !inetd_flag || debug_flag);
1667
1668 /*
1669 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1670 * root's environment
1671 */
1672 if (getenv("KRB5CCNAME") != NULL)
1673 (void) unsetenv("KRB5CCNAME");
1674
1675 sensitive_data.have_ssh2_key = 0;
1676
1677 /*
1678 * If we're not doing an extended test do not silently ignore connection
1679 * test params.
1680 */
1681 if (test_flag < 2 && connection_info != NULL)
1682 fatal("Config test connection parameter (-C) provided without "
1683 "test mode (-T)");
1684
1685 /* Fetch our configuration */
1686 if ((cfg = sshbuf_new()) == NULL)
1687 fatal("%s: sshbuf_new failed", __func__);
1688 if (rexeced_flag) {
1689 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
1690 if (!debug_flag) {
1691 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1692 close(REEXEC_STARTUP_PIPE_FD);
1693 /*
1694 * Signal parent that this child is at a point where
1695 * they can go away if they have a SIGHUP pending.
1696 */
1697 (void)atomicio(vwrite, startup_pipe, "\0", 1);
1698 }
1699 } else if (strcasecmp(config_file_name, "none") != 0)
1700 load_server_config(config_file_name, cfg);
1701
1702 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1703 cfg, &includes, NULL);
1704
1705 /* Fill in default values for those options not explicitly set. */
1706 fill_default_server_options(&options);
1707
1708 /* challenge-response is implemented via keyboard interactive */
1709 if (options.challenge_response_authentication)
1710 options.kbd_interactive_authentication = 1;
1711
1712 /* Check that options are sensible */
1713 if (options.authorized_keys_command_user == NULL &&
1714 (options.authorized_keys_command != NULL &&
1715 strcasecmp(options.authorized_keys_command, "none") != 0))
1716 fatal("AuthorizedKeysCommand set without "
1717 "AuthorizedKeysCommandUser");
1718 if (options.authorized_principals_command_user == NULL &&
1719 (options.authorized_principals_command != NULL &&
1720 strcasecmp(options.authorized_principals_command, "none") != 0))
1721 fatal("AuthorizedPrincipalsCommand set without "
1722 "AuthorizedPrincipalsCommandUser");
1723
1724 /*
1725 * Check whether there is any path through configured auth methods.
1726 * Unfortunately it is not possible to verify this generally before
1727 * daemonisation in the presence of Match block, but this catches
1728 * and warns for trivial misconfigurations that could break login.
1729 */
1730 if (options.num_auth_methods != 0) {
1731 for (i = 0; i < options.num_auth_methods; i++) {
1732 if (auth2_methods_valid(options.auth_methods[i],
1733 1) == 0)
1734 break;
1735 }
1736 if (i >= options.num_auth_methods)
1737 fatal("AuthenticationMethods cannot be satisfied by "
1738 "enabled authentication methods");
1739 }
1740
1741 /* Check that there are no remaining arguments. */
1742 if (optind < ac) {
1743 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1744 exit(1);
1745 }
1746
1747 debug("sshd version %s, %s", SSH_VERSION,
1748 #ifdef WITH_OPENSSL
1749 OpenSSL_version(OPENSSL_VERSION)
1750 #else
1751 "without OpenSSL"
1752 #endif
1753 );
1754
1755 /* Store privilege separation user for later use if required. */
1756 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1757 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1758 if (privsep_chroot || options.kerberos_authentication)
1759 fatal("Privilege separation user %s does not exist",
1760 SSH_PRIVSEP_USER);
1761 } else {
1762 privsep_pw = pwcopy(privsep_pw);
1763 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1764 privsep_pw->pw_passwd = xstrdup("*");
1765 }
1766 #if !defined(ANDROID)
1767 endpwent();
1768 #endif
1769
1770 /* load host keys */
1771 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1772 sizeof(struct sshkey *));
1773 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1774 sizeof(struct sshkey *));
1775
1776 if (options.host_key_agent) {
1777 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1778 setenv(SSH_AUTHSOCKET_ENV_NAME,
1779 options.host_key_agent, 1);
1780 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1781 have_agent = 1;
1782 else
1783 error("Could not connect to agent \"%s\": %s",
1784 options.host_key_agent, ssh_err(r));
1785 }
1786
1787 for (i = 0; i < options.num_host_key_files; i++) {
1788 int ll = options.host_key_file_userprovided[i] ?
1789 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1;
1790
1791 if (options.host_key_files[i] == NULL)
1792 continue;
1793 if ((r = sshkey_load_private(options.host_key_files[i], "",
1794 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1795 do_log2(ll, "Unable to load host key \"%s\": %s",
1796 options.host_key_files[i], ssh_err(r));
1797 if (sshkey_is_sk(key) &&
1798 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
1799 debug("host key %s requires user presence, ignoring",
1800 options.host_key_files[i]);
1801 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
1802 }
1803 if (r == 0 && key != NULL &&
1804 (r = sshkey_shield_private(key)) != 0) {
1805 do_log2(ll, "Unable to shield host key \"%s\": %s",
1806 options.host_key_files[i], ssh_err(r));
1807 sshkey_free(key);
1808 key = NULL;
1809 }
1810 if ((r = sshkey_load_public(options.host_key_files[i],
1811 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1812 do_log2(ll, "Unable to load host key \"%s\": %s",
1813 options.host_key_files[i], ssh_err(r));
1814 if (pubkey == NULL && key != NULL)
1815 if ((r = sshkey_from_private(key, &pubkey)) != 0)
1816 fatal("Could not demote key: \"%s\": %s",
1817 options.host_key_files[i], ssh_err(r));
1818 sensitive_data.host_keys[i] = key;
1819 sensitive_data.host_pubkeys[i] = pubkey;
1820
1821 if (key == NULL && pubkey != NULL && have_agent) {
1822 debug("will rely on agent for hostkey %s",
1823 options.host_key_files[i]);
1824 keytype = pubkey->type;
1825 } else if (key != NULL) {
1826 keytype = key->type;
1827 accumulate_host_timing_secret(cfg, key);
1828 } else {
1829 do_log2(ll, "Unable to load host key: %s",
1830 options.host_key_files[i]);
1831 sensitive_data.host_keys[i] = NULL;
1832 sensitive_data.host_pubkeys[i] = NULL;
1833 continue;
1834 }
1835
1836 switch (keytype) {
1837 case KEY_RSA:
1838 case KEY_DSA:
1839 case KEY_ECDSA:
1840 case KEY_ED25519:
1841 case KEY_ECDSA_SK:
1842 case KEY_ED25519_SK:
1843 case KEY_XMSS:
1844 if (have_agent || key != NULL)
1845 sensitive_data.have_ssh2_key = 1;
1846 break;
1847 }
1848 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1849 SSH_FP_DEFAULT)) == NULL)
1850 fatal("sshkey_fingerprint failed");
1851 debug("%s host key #%d: %s %s",
1852 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1853 free(fp);
1854 }
1855 accumulate_host_timing_secret(cfg, NULL);
1856 if (!sensitive_data.have_ssh2_key) {
1857 logit("sshd: no hostkeys available -- exiting.");
1858 exit(1);
1859 }
1860
1861 /*
1862 * Load certificates. They are stored in an array at identical
1863 * indices to the public keys that they relate to.
1864 */
1865 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1866 sizeof(struct sshkey *));
1867 for (i = 0; i < options.num_host_key_files; i++)
1868 sensitive_data.host_certificates[i] = NULL;
1869
1870 for (i = 0; i < options.num_host_cert_files; i++) {
1871 if (options.host_cert_files[i] == NULL)
1872 continue;
1873 if ((r = sshkey_load_public(options.host_cert_files[i],
1874 &key, NULL)) != 0) {
1875 error("Could not load host certificate \"%s\": %s",
1876 options.host_cert_files[i], ssh_err(r));
1877 continue;
1878 }
1879 if (!sshkey_is_cert(key)) {
1880 error("Certificate file is not a certificate: %s",
1881 options.host_cert_files[i]);
1882 sshkey_free(key);
1883 continue;
1884 }
1885 /* Find matching private key */
1886 for (j = 0; j < options.num_host_key_files; j++) {
1887 if (sshkey_equal_public(key,
1888 sensitive_data.host_keys[j])) {
1889 sensitive_data.host_certificates[j] = key;
1890 break;
1891 }
1892 }
1893 if (j >= options.num_host_key_files) {
1894 error("No matching private key for certificate: %s",
1895 options.host_cert_files[i]);
1896 sshkey_free(key);
1897 continue;
1898 }
1899 sensitive_data.host_certificates[j] = key;
1900 debug("host certificate: #%u type %d %s", j, key->type,
1901 sshkey_type(key));
1902 }
1903
1904 if (privsep_chroot) {
1905 struct stat st;
1906
1907 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1908 (S_ISDIR(st.st_mode) == 0))
1909 fatal("Missing privilege separation directory: %s",
1910 _PATH_PRIVSEP_CHROOT_DIR);
1911
1912 #ifdef HAVE_CYGWIN
1913 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1914 (st.st_uid != getuid () ||
1915 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1916 #else
1917 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1918 #endif
1919 fatal("%s must be owned by root and not group or "
1920 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1921 }
1922
1923 if (test_flag > 1) {
1924 /*
1925 * If no connection info was provided by -C then use
1926 * use a blank one that will cause no predicate to match.
1927 */
1928 if (connection_info == NULL)
1929 connection_info = get_connection_info(ssh, 0, 0);
1930 connection_info->test = 1;
1931 parse_server_match_config(&options, &includes, connection_info);
1932 dump_config(&options);
1933 }
1934
1935 /* Configuration looks good, so exit if in test mode. */
1936 if (test_flag)
1937 exit(0);
1938
1939 /*
1940 * Clear out any supplemental groups we may have inherited. This
1941 * prevents inadvertent creation of files with bad modes (in the
1942 * portable version at least, it's certainly possible for PAM
1943 * to create a file, and we can't control the code in every
1944 * module which might be used).
1945 */
1946 if (setgroups(0, NULL) < 0)
1947 debug("setgroups() failed: %.200s", strerror(errno));
1948
1949 if (rexec_flag) {
1950 if (rexec_argc < 0)
1951 fatal("rexec_argc %d < 0", rexec_argc);
1952 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1953 for (i = 0; i < (u_int)rexec_argc; i++) {
1954 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1955 rexec_argv[i] = saved_argv[i];
1956 }
1957 rexec_argv[rexec_argc] = "-R";
1958 rexec_argv[rexec_argc + 1] = NULL;
1959 }
1960 listener_proctitle = prepare_proctitle(ac, av);
1961
1962 /* Ensure that umask disallows at least group and world write */
1963 new_umask = umask(0077) | 0022;
1964 (void) umask(new_umask);
1965
1966 /* Initialize the log (it is reinitialized below in case we forked). */
1967 if (debug_flag && (!inetd_flag || rexeced_flag))
1968 log_stderr = 1;
1969 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1970
1971 /*
1972 * If not in debugging mode, not started from inetd and not already
1973 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1974 * terminal, and fork. The original process exits.
1975 */
1976 already_daemon = daemonized();
1977 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1978
1979 if (daemon(0, 0) == -1)
1980 fatal("daemon() failed: %.200s", strerror(errno));
1981
1982 disconnect_controlling_tty();
1983 }
1984 /* Reinitialize the log (because of the fork above). */
1985 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1986
1987 /* Chdir to the root directory so that the current disk can be
1988 unmounted if desired. */
1989 if (chdir("/") == -1)
1990 error("chdir(\"/\"): %s", strerror(errno));
1991
1992 /* ignore SIGPIPE */
1993 ssh_signal(SIGPIPE, SIG_IGN);
1994
1995 /* Get a connection, either from inetd or a listening TCP socket */
1996 if (inetd_flag) {
1997 server_accept_inetd(&sock_in, &sock_out);
1998 } else {
1999 platform_pre_listen();
2000 server_listen();
2001
2002 ssh_signal(SIGHUP, sighup_handler);
2003 ssh_signal(SIGCHLD, main_sigchld_handler);
2004 ssh_signal(SIGTERM, sigterm_handler);
2005 ssh_signal(SIGQUIT, sigterm_handler);
2006
2007 /*
2008 * Write out the pid file after the sigterm handler
2009 * is setup and the listen sockets are bound
2010 */
2011 if (options.pid_file != NULL && !debug_flag) {
2012 FILE *f = fopen(options.pid_file, "w");
2013
2014 if (f == NULL) {
2015 error("Couldn't create pid file \"%s\": %s",
2016 options.pid_file, strerror(errno));
2017 } else {
2018 fprintf(f, "%ld\n", (long) getpid());
2019 fclose(f);
2020 }
2021 }
2022
2023 /* Accept a connection and return in a forked child */
2024 server_accept_loop(&sock_in, &sock_out,
2025 &newsock, config_s);
2026 }
2027
2028 /* This is the child processing a new connection. */
2029 setproctitle("%s", "[accepted]");
2030
2031 /*
2032 * Create a new session and process group since the 4.4BSD
2033 * setlogin() affects the entire process group. We don't
2034 * want the child to be able to affect the parent.
2035 */
2036 #if !defined(SSHD_ACQUIRES_CTTY)
2037 /*
2038 * If setsid is called, on some platforms sshd will later acquire a
2039 * controlling terminal which will result in "could not set
2040 * controlling tty" errors.
2041 */
2042 if (!debug_flag && !inetd_flag && setsid() == -1)
2043 error("setsid: %.100s", strerror(errno));
2044 #endif
2045
2046 if (rexec_flag) {
2047 int fd;
2048
2049 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
2050 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2051 dup2(newsock, STDIN_FILENO);
2052 dup2(STDIN_FILENO, STDOUT_FILENO);
2053 if (startup_pipe == -1)
2054 close(REEXEC_STARTUP_PIPE_FD);
2055 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
2056 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
2057 close(startup_pipe);
2058 startup_pipe = REEXEC_STARTUP_PIPE_FD;
2059 }
2060
2061 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
2062 close(config_s[1]);
2063
2064 execv(rexec_argv[0], rexec_argv);
2065
2066 /* Reexec has failed, fall back and continue */
2067 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
2068 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
2069 log_init(__progname, options.log_level,
2070 options.log_facility, log_stderr);
2071
2072 /* Clean up fds */
2073 close(REEXEC_CONFIG_PASS_FD);
2074 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2075 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2076 dup2(fd, STDIN_FILENO);
2077 dup2(fd, STDOUT_FILENO);
2078 if (fd > STDERR_FILENO)
2079 close(fd);
2080 }
2081 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2082 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2083 }
2084
2085 /* Executed child processes don't need these. */
2086 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2087 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2088
2089 /* We will not restart on SIGHUP since it no longer makes sense. */
2090 ssh_signal(SIGALRM, SIG_DFL);
2091 ssh_signal(SIGHUP, SIG_DFL);
2092 ssh_signal(SIGTERM, SIG_DFL);
2093 ssh_signal(SIGQUIT, SIG_DFL);
2094 ssh_signal(SIGCHLD, SIG_DFL);
2095 ssh_signal(SIGINT, SIG_DFL);
2096
2097 /*
2098 * Register our connection. This turns encryption off because we do
2099 * not have a key.
2100 */
2101 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
2102 fatal("Unable to create connection");
2103 the_active_state = ssh;
2104 ssh_packet_set_server(ssh);
2105
2106 check_ip_options(ssh);
2107
2108 /* Prepare the channels layer */
2109 channel_init_channels(ssh);
2110 channel_set_af(ssh, options.address_family);
2111 process_permitopen(ssh, &options);
2112
2113 /* Set SO_KEEPALIVE if requested. */
2114 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) &&
2115 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1)
2116 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2117
2118 if ((remote_port = ssh_remote_port(ssh)) < 0) {
2119 debug("ssh_remote_port failed");
2120 cleanup_exit(255);
2121 }
2122
2123 if (options.routing_domain != NULL)
2124 set_process_rdomain(ssh, options.routing_domain);
2125
2126 /*
2127 * The rest of the code depends on the fact that
2128 * ssh_remote_ipaddr() caches the remote ip, even if
2129 * the socket goes away.
2130 */
2131 remote_ip = ssh_remote_ipaddr(ssh);
2132
2133 #ifdef SSH_AUDIT_EVENTS
2134 audit_connection_from(remote_ip, remote_port);
2135 #endif
2136
2137 rdomain = ssh_packet_rdomain_in(ssh);
2138
2139 /* Log the connection. */
2140 laddr = get_local_ipaddr(sock_in);
2141 verbose("Connection from %s port %d on %s port %d%s%s%s",
2142 remote_ip, remote_port, laddr, ssh_local_port(ssh),
2143 rdomain == NULL ? "" : " rdomain \"",
2144 rdomain == NULL ? "" : rdomain,
2145 rdomain == NULL ? "" : "\"");
2146 free(laddr);
2147
2148 /*
2149 * We don't want to listen forever unless the other side
2150 * successfully authenticates itself. So we set up an alarm which is
2151 * cleared after successful authentication. A limit of zero
2152 * indicates no limit. Note that we don't set the alarm in debugging
2153 * mode; it is just annoying to have the server exit just when you
2154 * are about to discover the bug.
2155 */
2156 ssh_signal(SIGALRM, grace_alarm_handler);
2157 if (!debug_flag)
2158 alarm(options.login_grace_time);
2159
2160 if ((r = kex_exchange_identification(ssh, -1,
2161 options.version_addendum)) != 0)
2162 sshpkt_fatal(ssh, r, "banner exchange");
2163
2164 ssh_packet_set_nonblocking(ssh);
2165
2166 /* allocate authentication context */
2167 authctxt = xcalloc(1, sizeof(*authctxt));
2168 ssh->authctxt = authctxt;
2169
2170 authctxt->loginmsg = loginmsg;
2171
2172 /* XXX global for cleanup, access from other modules */
2173 the_authctxt = authctxt;
2174
2175 /* Set default key authentication options */
2176 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
2177 fatal("allocation failed");
2178
2179 /* prepare buffer to collect messages to display to user after login */
2180 if ((loginmsg = sshbuf_new()) == NULL)
2181 fatal("%s: sshbuf_new failed", __func__);
2182 auth_debug_reset();
2183
2184 if (use_privsep) {
2185 if (privsep_preauth(ssh) == 1)
2186 goto authenticated;
2187 } else if (have_agent) {
2188 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2189 error("Unable to get agent socket: %s", ssh_err(r));
2190 have_agent = 0;
2191 }
2192 }
2193
2194 /* perform the key exchange */
2195 /* authenticate user and start session */
2196 do_ssh2_kex(ssh);
2197 do_authentication2(ssh);
2198
2199 /*
2200 * If we use privilege separation, the unprivileged child transfers
2201 * the current keystate and exits
2202 */
2203 if (use_privsep) {
2204 mm_send_keystate(ssh, pmonitor);
2205 ssh_packet_clear_keys(ssh);
2206 exit(0);
2207 }
2208
2209 authenticated:
2210 /*
2211 * Cancel the alarm we set to limit the time taken for
2212 * authentication.
2213 */
2214 alarm(0);
2215 ssh_signal(SIGALRM, SIG_DFL);
2216 authctxt->authenticated = 1;
2217 if (startup_pipe != -1) {
2218 close(startup_pipe);
2219 startup_pipe = -1;
2220 }
2221
2222 #ifdef SSH_AUDIT_EVENTS
2223 audit_event(ssh, SSH_AUTH_SUCCESS);
2224 #endif
2225
2226 #ifdef GSSAPI
2227 if (options.gss_authentication) {
2228 temporarily_use_uid(authctxt->pw);
2229 ssh_gssapi_storecreds();
2230 restore_uid();
2231 }
2232 #endif
2233 #ifdef USE_PAM
2234 if (options.use_pam) {
2235 do_pam_setcred(1);
2236 do_pam_session(ssh);
2237 }
2238 #endif
2239
2240 /*
2241 * In privilege separation, we fork another child and prepare
2242 * file descriptor passing.
2243 */
2244 if (use_privsep) {
2245 privsep_postauth(ssh, authctxt);
2246 /* the monitor process [priv] will not return */
2247 }
2248
2249 ssh_packet_set_timeout(ssh, options.client_alive_interval,
2250 options.client_alive_count_max);
2251
2252 /* Try to send all our hostkeys to the client */
2253 notify_hostkeys(ssh);
2254
2255 /* Start session. */
2256 do_authenticated(ssh, authctxt);
2257
2258 /* The connection has been terminated. */
2259 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
2260 verbose("Transferred: sent %llu, received %llu bytes",
2261 (unsigned long long)obytes, (unsigned long long)ibytes);
2262
2263 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2264
2265 #ifdef USE_PAM
2266 if (options.use_pam)
2267 finish_pam();
2268 #endif /* USE_PAM */
2269
2270 #ifdef SSH_AUDIT_EVENTS
2271 PRIVSEP(audit_event(ssh, SSH_CONNECTION_CLOSE));
2272 #endif
2273
2274 ssh_packet_close(ssh);
2275
2276 if (use_privsep)
2277 mm_terminate();
2278
2279 exit(0);
2280 }
2281
2282 int
2283 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
2284 struct sshkey *pubkey, u_char **signature, size_t *slenp,
2285 const u_char *data, size_t dlen, const char *alg)
2286 {
2287 int r;
2288
2289 if (use_privsep) {
2290 if (privkey) {
2291 if (mm_sshkey_sign(ssh, privkey, signature, slenp,
2292 data, dlen, alg, options.sk_provider,
2293 ssh->compat) < 0)
2294 fatal("%s: privkey sign failed", __func__);
2295 } else {
2296 if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
2297 data, dlen, alg, options.sk_provider,
2298 ssh->compat) < 0)
2299 fatal("%s: pubkey sign failed", __func__);
2300 }
2301 } else {
2302 if (privkey) {
2303 if (sshkey_sign(privkey, signature, slenp, data, dlen,
2304 alg, options.sk_provider, ssh->compat) < 0)
2305 fatal("%s: privkey sign failed", __func__);
2306 } else {
2307 if ((r = ssh_agent_sign(auth_sock, pubkey,
2308 signature, slenp, data, dlen, alg,
2309 ssh->compat)) != 0) {
2310 fatal("%s: agent sign failed: %s",
2311 __func__, ssh_err(r));
2312 }
2313 }
2314 }
2315 return 0;
2316 }
2317
2318 /* SSH2 key exchange */
2319 static void
2320 do_ssh2_kex(struct ssh *ssh)
2321 {
2322 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2323 struct kex *kex;
2324 int r;
2325
2326 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2327 options.kex_algorithms);
2328 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2329 options.ciphers);
2330 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2331 options.ciphers);
2332 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2333 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2334
2335 if (options.compression == COMP_NONE) {
2336 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2337 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2338 }
2339
2340 if (options.rekey_limit || options.rekey_interval)
2341 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
2342 options.rekey_interval);
2343
2344 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2345 list_hostkey_types());
2346
2347 /* start key exchange */
2348 if ((r = kex_setup(ssh, myproposal)) != 0)
2349 fatal("kex_setup: %s", ssh_err(r));
2350 kex = ssh->kex;
2351 #ifdef WITH_OPENSSL
2352 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
2353 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
2354 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
2355 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
2356 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
2357 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2358 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2359 # ifdef OPENSSL_HAS_ECC
2360 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
2361 # endif
2362 #endif
2363 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
2364 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server;
2365 kex->load_host_public_key=&get_hostkey_public_by_type;
2366 kex->load_host_private_key=&get_hostkey_private_by_type;
2367 kex->host_key_index=&get_hostkey_index;
2368 kex->sign = sshd_hostkey_sign;
2369
2370 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
2371
2372 session_id2 = kex->session_id;
2373 session_id2_len = kex->session_id_len;
2374
2375 #ifdef DEBUG_KEXDH
2376 /* send 1st encrypted/maced/compressed message */
2377 packet_start(SSH2_MSG_IGNORE);
2378 packet_put_cstring("markus");
2379 packet_send();
2380 packet_write_wait();
2381 #endif
2382 debug("KEX done");
2383 }
2384
2385 /* server specific fatal cleanup */
2386 void
2387 cleanup_exit(int i)
2388 {
2389 if (the_active_state != NULL && the_authctxt != NULL) {
2390 do_cleanup(the_active_state, the_authctxt);
2391 if (use_privsep && privsep_is_preauth &&
2392 pmonitor != NULL && pmonitor->m_pid > 1) {
2393 debug("Killing privsep child %d", pmonitor->m_pid);
2394 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2395 errno != ESRCH)
2396 error("%s: kill(%d): %s", __func__,
2397 pmonitor->m_pid, strerror(errno));
2398 }
2399 }
2400 #ifdef SSH_AUDIT_EVENTS
2401 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2402 if (the_active_state != NULL && (!use_privsep || mm_is_monitor()))
2403 audit_event(the_active_state, SSH_CONNECTION_ABANDON);
2404 #endif
2405 _exit(i);
2406 }
2407