1 /* $OpenBSD: sshd.c,v 1.514 2018/08/13 02:41:05 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <[email protected]>
4 * Copyright (c) 1995 Tatu Ylonen <[email protected]>, 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 __RCSID("$FreeBSD$");
47
48 #include <sys/types.h>
49 #include <sys/ioctl.h>
50 #include <sys/mman.h>
51 #include <sys/socket.h>
52 #ifdef HAVE_SYS_STAT_H
53 # include <sys/stat.h>
54 #endif
55 #ifdef HAVE_SYS_TIME_H
56 # include <sys/time.h>
57 #endif
58 #include "openbsd-compat/sys-tree.h"
59 #include "openbsd-compat/sys-queue.h"
60 #include <sys/wait.h>
61
62 #include <errno.h>
63 #include <fcntl.h>
64 #include <netdb.h>
65 #ifdef HAVE_PATHS_H
66 #include <paths.h>
67 #endif
68 #include <grp.h>
69 #include <pwd.h>
70 #include <signal.h>
71 #include <stdarg.h>
72 #include <stdio.h>
73 #include <stdlib.h>
74 #include <string.h>
75 #include <unistd.h>
76 #include <limits.h>
77
78 #ifdef WITH_OPENSSL
79 #include <openssl/dh.h>
80 #include <openssl/bn.h>
81 #include <openssl/rand.h>
82 #include "openbsd-compat/openssl-compat.h"
83 #endif
84
85 #ifdef HAVE_SECUREWARE
86 #include <sys/security.h>
87 #include <prot.h>
88 #endif
89
90 #ifdef __FreeBSD__
91 #include <resolv.h>
92 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H)
93 #include <gssapi/gssapi.h>
94 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H)
95 #include <gssapi.h>
96 #endif
97 #endif
98
99 #include "xmalloc.h"
100 #include "ssh.h"
101 #include "ssh2.h"
102 #include "sshpty.h"
103 #include "packet.h"
104 #include "log.h"
105 #include "sshbuf.h"
106 #include "misc.h"
107 #include "match.h"
108 #include "servconf.h"
109 #include "uidswap.h"
110 #include "compat.h"
111 #include "cipher.h"
112 #include "digest.h"
113 #include "sshkey.h"
114 #include "kex.h"
115 #include "myproposal.h"
116 #include "authfile.h"
117 #include "pathnames.h"
118 #include "atomicio.h"
119 #include "canohost.h"
120 #include "hostfile.h"
121 #include "auth.h"
122 #include "authfd.h"
123 #include "msg.h"
124 #include "dispatch.h"
125 #include "channels.h"
126 #include "session.h"
127 #include "monitor.h"
128 #ifdef GSSAPI
129 #include "ssh-gss.h"
130 #endif
131 #include "monitor_wrap.h"
132 #include "ssh-sandbox.h"
133 #include "auth-options.h"
134 #include "version.h"
135 #include "ssherr.h"
136 #include "blacklist_client.h"
137
138 #ifdef LIBWRAP
139 #include <tcpd.h>
140 #include <syslog.h>
141 int allow_severity;
142 int deny_severity;
143 #endif /* LIBWRAP */
144
145 /* Re-exec fds */
146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
150
151 extern char *__progname;
152
153 /* Server configuration options. */
154 ServerOptions options;
155
156 /* Name of the server configuration file. */
157 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
158
159 /*
160 * Debug mode flag. This can be set on the command line. If debug
161 * mode is enabled, extra debugging output will be sent to the system
162 * log, the daemon will not go to background, and will exit after processing
163 * the first connection.
164 */
165 int debug_flag = 0;
166
167 /*
168 * Indicating that the daemon should only test the configuration and keys.
169 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective
170 * configuration, optionally using connection information provided by the
171 * "-C" flag.
172 */
173 int test_flag = 0;
174
175 /* Flag indicating that the daemon is being started from inetd. */
176 int inetd_flag = 0;
177
178 /* Flag indicating that sshd should not detach and become a daemon. */
179 int no_daemon_flag = 0;
180
181 /* debug goes to stderr unless inetd_flag is set */
182 int log_stderr = 0;
183
184 /* Saved arguments to main(). */
185 char **saved_argv;
186 int saved_argc;
187
188 /* re-exec */
189 int rexeced_flag = 0;
190 int rexec_flag = 1;
191 int rexec_argc = 0;
192 char **rexec_argv;
193
194 /*
195 * The sockets that the server is listening; this is used in the SIGHUP
196 * signal handler.
197 */
198 #define MAX_LISTEN_SOCKS 16
199 int listen_socks[MAX_LISTEN_SOCKS];
200 int num_listen_socks = 0;
201
202 /*
203 * the client's version string, passed by sshd2 in compat mode. if != NULL,
204 * sshd will skip the version-number exchange
205 */
206 char *client_version_string = NULL;
207 char *server_version_string = NULL;
208
209 /* Daemon's agent connection */
210 int auth_sock = -1;
211 int have_agent = 0;
212
213 /*
214 * Any really sensitive data in the application is contained in this
215 * structure. The idea is that this structure could be locked into memory so
216 * that the pages do not get written into swap. However, there are some
217 * problems. The private key contains BIGNUMs, and we do not (in principle)
218 * have access to the internals of them, and locking just the structure is
219 * not very useful. Currently, memory locking is not implemented.
220 */
221 struct {
222 struct sshkey **host_keys; /* all private host keys */
223 struct sshkey **host_pubkeys; /* all public host keys */
224 struct sshkey **host_certificates; /* all public host certificates */
225 int have_ssh2_key;
226 } sensitive_data;
227
228 /* This is set to true when a signal is received. */
229 static volatile sig_atomic_t received_sighup = 0;
230 static volatile sig_atomic_t received_sigterm = 0;
231
232 /* session identifier, used by RSA-auth */
233 u_char session_id[16];
234
235 /* same for ssh2 */
236 u_char *session_id2 = NULL;
237 u_int session_id2_len = 0;
238
239 /* record remote hostname or ip */
240 u_int utmp_len = HOST_NAME_MAX+1;
241
242 /* options.max_startup sized array of fd ints */
243 int *startup_pipes = NULL;
244 int startup_pipe; /* in child */
245
246 /* variables used for privilege separation */
247 int use_privsep = -1;
248 struct monitor *pmonitor = NULL;
249 int privsep_is_preauth = 1;
250 static int privsep_chroot = 1;
251
252 /* global authentication context */
253 Authctxt *the_authctxt = NULL;
254
255 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
256 struct sshauthopt *auth_opts = NULL;
257
258 /* sshd_config buffer */
259 struct sshbuf *cfg;
260
261 /* message to be displayed after login */
262 struct sshbuf *loginmsg;
263
264 /* Unprivileged user */
265 struct passwd *privsep_pw = NULL;
266
267 /* Prototypes for various functions defined later in this file. */
268 void destroy_sensitive_data(void);
269 void demote_sensitive_data(void);
270 static void do_ssh2_kex(void);
271
272 /*
273 * Close all listening sockets
274 */
275 static void
close_listen_socks(void)276 close_listen_socks(void)
277 {
278 int i;
279
280 for (i = 0; i < num_listen_socks; i++)
281 close(listen_socks[i]);
282 num_listen_socks = -1;
283 }
284
285 static void
close_startup_pipes(void)286 close_startup_pipes(void)
287 {
288 int i;
289
290 if (startup_pipes)
291 for (i = 0; i < options.max_startups; i++)
292 if (startup_pipes[i] != -1)
293 close(startup_pipes[i]);
294 }
295
296 /*
297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
298 * the effect is to reread the configuration file (and to regenerate
299 * the server key).
300 */
301
302 /*ARGSUSED*/
303 static void
sighup_handler(int sig)304 sighup_handler(int sig)
305 {
306 int save_errno = errno;
307
308 received_sighup = 1;
309 errno = save_errno;
310 }
311
312 /*
313 * Called from the main program after receiving SIGHUP.
314 * Restarts the server.
315 */
316 static void
sighup_restart(void)317 sighup_restart(void)
318 {
319 logit("Received SIGHUP; restarting.");
320 if (options.pid_file != NULL)
321 unlink(options.pid_file);
322 platform_pre_restart();
323 close_listen_socks();
324 close_startup_pipes();
325 alarm(0); /* alarm timer persists across exec */
326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
327 execv(saved_argv[0], saved_argv);
328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
329 strerror(errno));
330 exit(1);
331 }
332
333 /*
334 * Generic signal handler for terminating signals in the master daemon.
335 */
336 /*ARGSUSED*/
337 static void
sigterm_handler(int sig)338 sigterm_handler(int sig)
339 {
340 received_sigterm = sig;
341 }
342
343 /*
344 * SIGCHLD handler. This is called whenever a child dies. This will then
345 * reap any zombies left by exited children.
346 */
347 /*ARGSUSED*/
348 static void
main_sigchld_handler(int sig)349 main_sigchld_handler(int sig)
350 {
351 int save_errno = errno;
352 pid_t pid;
353 int status;
354
355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
356 (pid < 0 && errno == EINTR))
357 ;
358 errno = save_errno;
359 }
360
361 /*
362 * Signal handler for the alarm after the login grace period has expired.
363 */
364 /*ARGSUSED*/
365 static void
grace_alarm_handler(int sig)366 grace_alarm_handler(int sig)
367 {
368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
369 kill(pmonitor->m_pid, SIGALRM);
370
371 /*
372 * Try to kill any processes that we have spawned, E.g. authorized
373 * keys command helpers.
374 */
375 if (getpgid(0) == getpid()) {
376 signal(SIGTERM, SIG_IGN);
377 kill(0, SIGTERM);
378 }
379
380 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh");
381
382 /* Log error and exit. */
383 sigdie("Timeout before authentication for %s port %d",
384 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state));
385 }
386
387 static void
sshd_exchange_identification(struct ssh * ssh,int sock_in,int sock_out)388 sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out)
389 {
390 u_int i;
391 int remote_major, remote_minor;
392 char *s;
393 char buf[256]; /* Must not be larger than remote_version. */
394 char remote_version[256]; /* Must be at least as big as buf. */
395
396 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n",
397 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION,
398 *options.version_addendum == '\0' ? "" : " ",
399 options.version_addendum);
400
401 /* Send our protocol version identification. */
402 if (atomicio(vwrite, sock_out, server_version_string,
403 strlen(server_version_string))
404 != strlen(server_version_string)) {
405 logit("Could not write ident string to %s port %d",
406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
407 cleanup_exit(255);
408 }
409
410 /* Read other sides version identification. */
411 memset(buf, 0, sizeof(buf));
412 for (i = 0; i < sizeof(buf) - 1; i++) {
413 if (atomicio(read, sock_in, &buf[i], 1) != 1) {
414 logit("Did not receive identification string "
415 "from %s port %d",
416 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
417 cleanup_exit(255);
418 }
419 if (buf[i] == '\r') {
420 buf[i] = 0;
421 /* Kludge for F-Secure Macintosh < 1.0.2 */
422 if (i == 12 &&
423 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
424 break;
425 continue;
426 }
427 if (buf[i] == '\n') {
428 buf[i] = 0;
429 break;
430 }
431 }
432 buf[sizeof(buf) - 1] = 0;
433 client_version_string = xstrdup(buf);
434
435 /*
436 * Check that the versions match. In future this might accept
437 * several versions and set appropriate flags to handle them.
438 */
439 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
440 &remote_major, &remote_minor, remote_version) != 3) {
441 s = "Protocol mismatch.\n";
442 (void) atomicio(vwrite, sock_out, s, strlen(s));
443 logit("Bad protocol version identification '%.100s' "
444 "from %s port %d", client_version_string,
445 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
446 close(sock_in);
447 close(sock_out);
448 cleanup_exit(255);
449 }
450 debug("Client protocol version %d.%d; client software version %.100s",
451 remote_major, remote_minor, remote_version);
452
453 ssh->compat = compat_datafellows(remote_version);
454
455 if ((ssh->compat & SSH_BUG_PROBE) != 0) {
456 logit("probed from %s port %d with %s. Don't panic.",
457 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
458 client_version_string);
459 cleanup_exit(255);
460 }
461 if ((ssh->compat & SSH_BUG_SCANNER) != 0) {
462 logit("scanned from %s port %d with %s. Don't panic.",
463 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
464 client_version_string);
465 cleanup_exit(255);
466 }
467 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
468 logit("Client version \"%.100s\" uses unsafe RSA signature "
469 "scheme; disabling use of RSA keys", remote_version);
470 }
471
472 chop(server_version_string);
473 debug("Local version string %.200s", server_version_string);
474
475 if (remote_major != 2 &&
476 !(remote_major == 1 && remote_minor == 99)) {
477 s = "Protocol major versions differ.\n";
478 (void) atomicio(vwrite, sock_out, s, strlen(s));
479 close(sock_in);
480 close(sock_out);
481 logit("Protocol major versions differ for %s port %d: "
482 "%.200s vs. %.200s",
483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
484 server_version_string, client_version_string);
485 cleanup_exit(255);
486 }
487 }
488
489 /* Destroy the host and server keys. They will no longer be needed. */
490 void
destroy_sensitive_data(void)491 destroy_sensitive_data(void)
492 {
493 u_int i;
494
495 for (i = 0; i < options.num_host_key_files; i++) {
496 if (sensitive_data.host_keys[i]) {
497 sshkey_free(sensitive_data.host_keys[i]);
498 sensitive_data.host_keys[i] = NULL;
499 }
500 if (sensitive_data.host_certificates[i]) {
501 sshkey_free(sensitive_data.host_certificates[i]);
502 sensitive_data.host_certificates[i] = NULL;
503 }
504 }
505 }
506
507 /* Demote private to public keys for network child */
508 void
demote_sensitive_data(void)509 demote_sensitive_data(void)
510 {
511 struct sshkey *tmp;
512 u_int i;
513 int r;
514
515 for (i = 0; i < options.num_host_key_files; i++) {
516 if (sensitive_data.host_keys[i]) {
517 if ((r = sshkey_from_private(
518 sensitive_data.host_keys[i], &tmp)) != 0)
519 fatal("could not demote host %s key: %s",
520 sshkey_type(sensitive_data.host_keys[i]),
521 ssh_err(r));
522 sshkey_free(sensitive_data.host_keys[i]);
523 sensitive_data.host_keys[i] = tmp;
524 }
525 /* Certs do not need demotion */
526 }
527 }
528
529 static void
reseed_prngs(void)530 reseed_prngs(void)
531 {
532 u_int32_t rnd[256];
533
534 #ifdef WITH_OPENSSL
535 RAND_poll();
536 #endif
537 arc4random_stir(); /* noop on recent arc4random() implementations */
538 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
539
540 #ifdef WITH_OPENSSL
541 RAND_seed(rnd, sizeof(rnd));
542 /* give libcrypto a chance to notice the PID change */
543 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
544 fatal("%s: RAND_bytes failed", __func__);
545 #endif
546
547 explicit_bzero(rnd, sizeof(rnd));
548 }
549
550 static void
privsep_preauth_child(void)551 privsep_preauth_child(void)
552 {
553 gid_t gidset[1];
554
555 /* Enable challenge-response authentication for privilege separation */
556 privsep_challenge_enable();
557
558 #ifdef GSSAPI
559 /* Cache supported mechanism OIDs for later use */
560 if (options.gss_authentication)
561 ssh_gssapi_prepare_supported_oids();
562 #endif
563
564 reseed_prngs();
565
566 /* Demote the private keys to public keys. */
567 demote_sensitive_data();
568
569 /* Demote the child */
570 if (privsep_chroot) {
571 /* Change our root directory */
572 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
573 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
574 strerror(errno));
575 if (chdir("/") == -1)
576 fatal("chdir(\"/\"): %s", strerror(errno));
577
578 /* Drop our privileges */
579 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
580 (u_int)privsep_pw->pw_gid);
581 gidset[0] = privsep_pw->pw_gid;
582 if (setgroups(1, gidset) < 0)
583 fatal("setgroups: %.100s", strerror(errno));
584 permanently_set_uid(privsep_pw);
585 }
586 }
587
588 static int
privsep_preauth(Authctxt * authctxt)589 privsep_preauth(Authctxt *authctxt)
590 {
591 int status, r;
592 pid_t pid;
593 struct ssh_sandbox *box = NULL;
594
595 /* Set up unprivileged child process to deal with network data */
596 pmonitor = monitor_init();
597 /* Store a pointer to the kex for later rekeying */
598 pmonitor->m_pkex = &active_state->kex;
599
600 if (use_privsep == PRIVSEP_ON)
601 box = ssh_sandbox_init(pmonitor);
602 pid = fork();
603 if (pid == -1) {
604 fatal("fork of unprivileged child failed");
605 } else if (pid != 0) {
606 debug2("Network child is on pid %ld", (long)pid);
607
608 pmonitor->m_pid = pid;
609 if (have_agent) {
610 r = ssh_get_authentication_socket(&auth_sock);
611 if (r != 0) {
612 error("Could not get agent socket: %s",
613 ssh_err(r));
614 have_agent = 0;
615 }
616 }
617 if (box != NULL)
618 ssh_sandbox_parent_preauth(box, pid);
619 monitor_child_preauth(authctxt, pmonitor);
620
621 /* Wait for the child's exit status */
622 while (waitpid(pid, &status, 0) < 0) {
623 if (errno == EINTR)
624 continue;
625 pmonitor->m_pid = -1;
626 fatal("%s: waitpid: %s", __func__, strerror(errno));
627 }
628 privsep_is_preauth = 0;
629 pmonitor->m_pid = -1;
630 if (WIFEXITED(status)) {
631 if (WEXITSTATUS(status) != 0)
632 fatal("%s: preauth child exited with status %d",
633 __func__, WEXITSTATUS(status));
634 } else if (WIFSIGNALED(status))
635 fatal("%s: preauth child terminated by signal %d",
636 __func__, WTERMSIG(status));
637 if (box != NULL)
638 ssh_sandbox_parent_finish(box);
639 return 1;
640 } else {
641 /* child */
642 close(pmonitor->m_sendfd);
643 close(pmonitor->m_log_recvfd);
644
645 /* Arrange for logging to be sent to the monitor */
646 set_log_handler(mm_log_handler, pmonitor);
647
648 privsep_preauth_child();
649 setproctitle("%s", "[net]");
650 if (box != NULL)
651 ssh_sandbox_child(box);
652
653 return 0;
654 }
655 }
656
657 static void
privsep_postauth(Authctxt * authctxt)658 privsep_postauth(Authctxt *authctxt)
659 {
660 #ifdef DISABLE_FD_PASSING
661 if (1) {
662 #else
663 if (authctxt->pw->pw_uid == 0) {
664 #endif
665 /* File descriptor passing is broken or root login */
666 use_privsep = 0;
667 goto skip;
668 }
669
670 /* New socket pair */
671 monitor_reinit(pmonitor);
672
673 pmonitor->m_pid = fork();
674 if (pmonitor->m_pid == -1)
675 fatal("fork of unprivileged child failed");
676 else if (pmonitor->m_pid != 0) {
677 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
678 sshbuf_reset(loginmsg);
679 monitor_clear_keystate(pmonitor);
680 monitor_child_postauth(pmonitor);
681
682 /* NEVERREACHED */
683 exit(0);
684 }
685
686 /* child */
687
688 close(pmonitor->m_sendfd);
689 pmonitor->m_sendfd = -1;
690
691 /* Demote the private keys to public keys. */
692 demote_sensitive_data();
693
694 reseed_prngs();
695
696 /* Drop privileges */
697 do_setusercontext(authctxt->pw);
698
699 skip:
700 /* It is safe now to apply the key state */
701 monitor_apply_keystate(pmonitor);
702
703 /*
704 * Tell the packet layer that authentication was successful, since
705 * this information is not part of the key state.
706 */
707 packet_set_authenticated();
708 }
709
710 static void
711 append_hostkey_type(struct sshbuf *b, const char *s)
712 {
713 int r;
714
715 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
716 debug3("%s: %s key not permitted by HostkeyAlgorithms",
717 __func__, s);
718 return;
719 }
720 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
721 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r));
722 }
723
724 static char *
725 list_hostkey_types(void)
726 {
727 struct sshbuf *b;
728 struct sshkey *key;
729 char *ret;
730 u_int i;
731
732 if ((b = sshbuf_new()) == NULL)
733 fatal("%s: sshbuf_new failed", __func__);
734 for (i = 0; i < options.num_host_key_files; i++) {
735 key = sensitive_data.host_keys[i];
736 if (key == NULL)
737 key = sensitive_data.host_pubkeys[i];
738 if (key == NULL)
739 continue;
740 switch (key->type) {
741 case KEY_RSA:
742 /* for RSA we also support SHA2 signatures */
743 append_hostkey_type(b, "rsa-sha2-512");
744 append_hostkey_type(b, "rsa-sha2-256");
745 /* FALLTHROUGH */
746 case KEY_DSA:
747 case KEY_ECDSA:
748 case KEY_ED25519:
749 case KEY_XMSS:
750 append_hostkey_type(b, sshkey_ssh_name(key));
751 break;
752 }
753 /* If the private key has a cert peer, then list that too */
754 key = sensitive_data.host_certificates[i];
755 if (key == NULL)
756 continue;
757 switch (key->type) {
758 case KEY_RSA_CERT:
759 /* for RSA we also support SHA2 signatures */
760 append_hostkey_type(b,
761 "[email protected]");
762 append_hostkey_type(b,
763 "[email protected]");
764 /* FALLTHROUGH */
765 case KEY_DSA_CERT:
766 case KEY_ECDSA_CERT:
767 case KEY_ED25519_CERT:
768 case KEY_XMSS_CERT:
769 append_hostkey_type(b, sshkey_ssh_name(key));
770 break;
771 }
772 }
773 if ((ret = sshbuf_dup_string(b)) == NULL)
774 fatal("%s: sshbuf_dup_string failed", __func__);
775 sshbuf_free(b);
776 debug("%s: %s", __func__, ret);
777 return ret;
778 }
779
780 static struct sshkey *
781 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
782 {
783 u_int i;
784 struct sshkey *key;
785
786 for (i = 0; i < options.num_host_key_files; i++) {
787 switch (type) {
788 case KEY_RSA_CERT:
789 case KEY_DSA_CERT:
790 case KEY_ECDSA_CERT:
791 case KEY_ED25519_CERT:
792 case KEY_XMSS_CERT:
793 key = sensitive_data.host_certificates[i];
794 break;
795 default:
796 key = sensitive_data.host_keys[i];
797 if (key == NULL && !need_private)
798 key = sensitive_data.host_pubkeys[i];
799 break;
800 }
801 if (key != NULL && key->type == type &&
802 (key->type != KEY_ECDSA || key->ecdsa_nid == nid))
803 return need_private ?
804 sensitive_data.host_keys[i] : key;
805 }
806 return NULL;
807 }
808
809 struct sshkey *
810 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
811 {
812 return get_hostkey_by_type(type, nid, 0, ssh);
813 }
814
815 struct sshkey *
816 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
817 {
818 return get_hostkey_by_type(type, nid, 1, ssh);
819 }
820
821 struct sshkey *
822 get_hostkey_by_index(int ind)
823 {
824 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
825 return (NULL);
826 return (sensitive_data.host_keys[ind]);
827 }
828
829 struct sshkey *
830 get_hostkey_public_by_index(int ind, struct ssh *ssh)
831 {
832 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
833 return (NULL);
834 return (sensitive_data.host_pubkeys[ind]);
835 }
836
837 int
838 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
839 {
840 u_int i;
841
842 for (i = 0; i < options.num_host_key_files; i++) {
843 if (sshkey_is_cert(key)) {
844 if (key == sensitive_data.host_certificates[i] ||
845 (compare && sensitive_data.host_certificates[i] &&
846 sshkey_equal(key,
847 sensitive_data.host_certificates[i])))
848 return (i);
849 } else {
850 if (key == sensitive_data.host_keys[i] ||
851 (compare && sensitive_data.host_keys[i] &&
852 sshkey_equal(key, sensitive_data.host_keys[i])))
853 return (i);
854 if (key == sensitive_data.host_pubkeys[i] ||
855 (compare && sensitive_data.host_pubkeys[i] &&
856 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
857 return (i);
858 }
859 }
860 return (-1);
861 }
862
863 /* Inform the client of all hostkeys */
864 static void
865 notify_hostkeys(struct ssh *ssh)
866 {
867 struct sshbuf *buf;
868 struct sshkey *key;
869 u_int i, nkeys;
870 int r;
871 char *fp;
872
873 /* Some clients cannot cope with the hostkeys message, skip those. */
874 if (datafellows & SSH_BUG_HOSTKEYS)
875 return;
876
877 if ((buf = sshbuf_new()) == NULL)
878 fatal("%s: sshbuf_new", __func__);
879 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
880 key = get_hostkey_public_by_index(i, ssh);
881 if (key == NULL || key->type == KEY_UNSPEC ||
882 sshkey_is_cert(key))
883 continue;
884 fp = sshkey_fingerprint(key, options.fingerprint_hash,
885 SSH_FP_DEFAULT);
886 debug3("%s: key %d: %s %s", __func__, i,
887 sshkey_ssh_name(key), fp);
888 free(fp);
889 if (nkeys == 0) {
890 packet_start(SSH2_MSG_GLOBAL_REQUEST);
891 packet_put_cstring("[email protected]");
892 packet_put_char(0); /* want-reply */
893 }
894 sshbuf_reset(buf);
895 if ((r = sshkey_putb(key, buf)) != 0)
896 fatal("%s: couldn't put hostkey %d: %s",
897 __func__, i, ssh_err(r));
898 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf));
899 nkeys++;
900 }
901 debug3("%s: sent %u hostkeys", __func__, nkeys);
902 if (nkeys == 0)
903 fatal("%s: no hostkeys", __func__);
904 packet_send();
905 sshbuf_free(buf);
906 }
907
908 /*
909 * returns 1 if connection should be dropped, 0 otherwise.
910 * dropping starts at connection #max_startups_begin with a probability
911 * of (max_startups_rate/100). the probability increases linearly until
912 * all connections are dropped for startups > max_startups
913 */
914 static int
915 drop_connection(int startups)
916 {
917 int p, r;
918
919 if (startups < options.max_startups_begin)
920 return 0;
921 if (startups >= options.max_startups)
922 return 1;
923 if (options.max_startups_rate == 100)
924 return 1;
925
926 p = 100 - options.max_startups_rate;
927 p *= startups - options.max_startups_begin;
928 p /= options.max_startups - options.max_startups_begin;
929 p += options.max_startups_rate;
930 r = arc4random_uniform(100);
931
932 debug("drop_connection: p %d, r %d", p, r);
933 return (r < p) ? 1 : 0;
934 }
935
936 static void
937 usage(void)
938 {
939 if (options.version_addendum && *options.version_addendum != '\0')
940 fprintf(stderr, "%s %s, %s\n",
941 SSH_RELEASE,
942 options.version_addendum, OPENSSL_VERSION_STRING);
943 else
944 fprintf(stderr, "%s, %s\n",
945 SSH_RELEASE, OPENSSL_VERSION_STRING);
946 fprintf(stderr,
947 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n"
948 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
949 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
950 );
951 exit(1);
952 }
953
954 static void
955 send_rexec_state(int fd, struct sshbuf *conf)
956 {
957 struct sshbuf *m;
958 int r;
959
960 debug3("%s: entering fd = %d config len %zu", __func__, fd,
961 sshbuf_len(conf));
962
963 /*
964 * Protocol from reexec master to child:
965 * string configuration
966 * string rngseed (only if OpenSSL is not self-seeded)
967 */
968 if ((m = sshbuf_new()) == NULL)
969 fatal("%s: sshbuf_new failed", __func__);
970 if ((r = sshbuf_put_stringb(m, conf)) != 0)
971 fatal("%s: buffer error: %s", __func__, ssh_err(r));
972
973 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
974 rexec_send_rng_seed(m);
975 #endif
976
977 if (ssh_msg_send(fd, 0, m) == -1)
978 fatal("%s: ssh_msg_send failed", __func__);
979
980 sshbuf_free(m);
981
982 debug3("%s: done", __func__);
983 }
984
985 static void
986 recv_rexec_state(int fd, struct sshbuf *conf)
987 {
988 struct sshbuf *m;
989 u_char *cp, ver;
990 size_t len;
991 int r;
992
993 debug3("%s: entering fd = %d", __func__, fd);
994
995 if ((m = sshbuf_new()) == NULL)
996 fatal("%s: sshbuf_new failed", __func__);
997 if (ssh_msg_recv(fd, m) == -1)
998 fatal("%s: ssh_msg_recv failed", __func__);
999 if ((r = sshbuf_get_u8(m, &ver)) != 0)
1000 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1001 if (ver != 0)
1002 fatal("%s: rexec version mismatch", __func__);
1003 if ((r = sshbuf_get_string(m, &cp, &len)) != 0)
1004 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1005 if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
1006 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1007 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY)
1008 rexec_recv_rng_seed(m);
1009 #endif
1010
1011 free(cp);
1012 sshbuf_free(m);
1013
1014 debug3("%s: done", __func__);
1015 }
1016
1017 /* Accept a connection from inetd */
1018 static void
1019 server_accept_inetd(int *sock_in, int *sock_out)
1020 {
1021 int fd;
1022
1023 startup_pipe = -1;
1024 if (rexeced_flag) {
1025 close(REEXEC_CONFIG_PASS_FD);
1026 *sock_in = *sock_out = dup(STDIN_FILENO);
1027 if (!debug_flag) {
1028 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1029 close(REEXEC_STARTUP_PIPE_FD);
1030 }
1031 } else {
1032 *sock_in = dup(STDIN_FILENO);
1033 *sock_out = dup(STDOUT_FILENO);
1034 }
1035 /*
1036 * We intentionally do not close the descriptors 0, 1, and 2
1037 * as our code for setting the descriptors won't work if
1038 * ttyfd happens to be one of those.
1039 */
1040 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1041 dup2(fd, STDIN_FILENO);
1042 dup2(fd, STDOUT_FILENO);
1043 if (!log_stderr)
1044 dup2(fd, STDERR_FILENO);
1045 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO))
1046 close(fd);
1047 }
1048 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1049 }
1050
1051 /*
1052 * Listen for TCP connections
1053 */
1054 static void
1055 listen_on_addrs(struct listenaddr *la)
1056 {
1057 int ret, listen_sock;
1058 struct addrinfo *ai;
1059 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1060 int socksize;
1061 socklen_t len;
1062
1063 for (ai = la->addrs; ai; ai = ai->ai_next) {
1064 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1065 continue;
1066 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1067 fatal("Too many listen sockets. "
1068 "Enlarge MAX_LISTEN_SOCKS");
1069 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1070 ntop, sizeof(ntop), strport, sizeof(strport),
1071 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1072 error("getnameinfo failed: %.100s",
1073 ssh_gai_strerror(ret));
1074 continue;
1075 }
1076 /* Create socket for listening. */
1077 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1078 ai->ai_protocol);
1079 if (listen_sock < 0) {
1080 /* kernel may not support ipv6 */
1081 verbose("socket: %.100s", strerror(errno));
1082 continue;
1083 }
1084 if (set_nonblock(listen_sock) == -1) {
1085 close(listen_sock);
1086 continue;
1087 }
1088 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
1089 verbose("socket: CLOEXEC: %s", strerror(errno));
1090 close(listen_sock);
1091 continue;
1092 }
1093 /* Socket options */
1094 set_reuseaddr(listen_sock);
1095 if (la->rdomain != NULL &&
1096 set_rdomain(listen_sock, la->rdomain) == -1) {
1097 close(listen_sock);
1098 continue;
1099 }
1100
1101 /* Only communicate in IPv6 over AF_INET6 sockets. */
1102 if (ai->ai_family == AF_INET6)
1103 sock_set_v6only(listen_sock);
1104
1105 debug("Bind to port %s on %s.", strport, ntop);
1106
1107 len = sizeof(socksize);
1108 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len);
1109 debug("Server TCP RWIN socket size: %d", socksize);
1110
1111 /* Bind the socket to the desired port. */
1112 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1113 error("Bind to port %s on %s failed: %.200s.",
1114 strport, ntop, strerror(errno));
1115 close(listen_sock);
1116 continue;
1117 }
1118 listen_socks[num_listen_socks] = listen_sock;
1119 num_listen_socks++;
1120
1121 /* Start listening on the port. */
1122 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1123 fatal("listen on [%s]:%s: %.100s",
1124 ntop, strport, strerror(errno));
1125 logit("Server listening on %s port %s%s%s.",
1126 ntop, strport,
1127 la->rdomain == NULL ? "" : " rdomain ",
1128 la->rdomain == NULL ? "" : la->rdomain);
1129 }
1130 }
1131
1132 static void
1133 server_listen(void)
1134 {
1135 u_int i;
1136
1137 for (i = 0; i < options.num_listen_addrs; i++) {
1138 listen_on_addrs(&options.listen_addrs[i]);
1139 freeaddrinfo(options.listen_addrs[i].addrs);
1140 free(options.listen_addrs[i].rdomain);
1141 memset(&options.listen_addrs[i], 0,
1142 sizeof(options.listen_addrs[i]));
1143 }
1144 free(options.listen_addrs);
1145 options.listen_addrs = NULL;
1146 options.num_listen_addrs = 0;
1147
1148 if (!num_listen_socks)
1149 fatal("Cannot bind any address.");
1150 }
1151
1152 /*
1153 * The main TCP accept loop. Note that, for the non-debug case, returns
1154 * from this function are in a forked subprocess.
1155 */
1156 static void
1157 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1158 {
1159 fd_set *fdset;
1160 int i, j, ret, maxfd;
1161 int startups = 0;
1162 int startup_p[2] = { -1 , -1 };
1163 struct sockaddr_storage from;
1164 socklen_t fromlen;
1165 pid_t pid;
1166 u_char rnd[256];
1167
1168 /* setup fd set for accept */
1169 fdset = NULL;
1170 maxfd = 0;
1171 for (i = 0; i < num_listen_socks; i++)
1172 if (listen_socks[i] > maxfd)
1173 maxfd = listen_socks[i];
1174 /* pipes connected to unauthenticated childs */
1175 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1176 for (i = 0; i < options.max_startups; i++)
1177 startup_pipes[i] = -1;
1178
1179 /*
1180 * Stay listening for connections until the system crashes or
1181 * the daemon is killed with a signal.
1182 */
1183 for (;;) {
1184 if (received_sighup)
1185 sighup_restart();
1186 free(fdset);
1187 fdset = xcalloc(howmany(maxfd + 1, NFDBITS),
1188 sizeof(fd_mask));
1189
1190 for (i = 0; i < num_listen_socks; i++)
1191 FD_SET(listen_socks[i], fdset);
1192 for (i = 0; i < options.max_startups; i++)
1193 if (startup_pipes[i] != -1)
1194 FD_SET(startup_pipes[i], fdset);
1195
1196 /* Wait in select until there is a connection. */
1197 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1198 if (ret < 0 && errno != EINTR)
1199 error("select: %.100s", strerror(errno));
1200 if (received_sigterm) {
1201 logit("Received signal %d; terminating.",
1202 (int) received_sigterm);
1203 close_listen_socks();
1204 if (options.pid_file != NULL)
1205 unlink(options.pid_file);
1206 exit(received_sigterm == SIGTERM ? 0 : 255);
1207 }
1208 if (ret < 0)
1209 continue;
1210
1211 for (i = 0; i < options.max_startups; i++)
1212 if (startup_pipes[i] != -1 &&
1213 FD_ISSET(startup_pipes[i], fdset)) {
1214 /*
1215 * the read end of the pipe is ready
1216 * if the child has closed the pipe
1217 * after successful authentication
1218 * or if the child has died
1219 */
1220 close(startup_pipes[i]);
1221 startup_pipes[i] = -1;
1222 startups--;
1223 }
1224 for (i = 0; i < num_listen_socks; i++) {
1225 if (!FD_ISSET(listen_socks[i], fdset))
1226 continue;
1227 fromlen = sizeof(from);
1228 *newsock = accept(listen_socks[i],
1229 (struct sockaddr *)&from, &fromlen);
1230 if (*newsock < 0) {
1231 if (errno != EINTR && errno != EWOULDBLOCK &&
1232 errno != ECONNABORTED && errno != EAGAIN)
1233 error("accept: %.100s",
1234 strerror(errno));
1235 if (errno == EMFILE || errno == ENFILE)
1236 usleep(100 * 1000);
1237 continue;
1238 }
1239 if (unset_nonblock(*newsock) == -1) {
1240 close(*newsock);
1241 continue;
1242 }
1243 if (drop_connection(startups) == 1) {
1244 char *laddr = get_local_ipaddr(*newsock);
1245 char *raddr = get_peer_ipaddr(*newsock);
1246
1247 verbose("drop connection #%d from [%s]:%d "
1248 "on [%s]:%d past MaxStartups", startups,
1249 raddr, get_peer_port(*newsock),
1250 laddr, get_local_port(*newsock));
1251 free(laddr);
1252 free(raddr);
1253 close(*newsock);
1254 continue;
1255 }
1256 if (pipe(startup_p) == -1) {
1257 close(*newsock);
1258 continue;
1259 }
1260
1261 if (rexec_flag && socketpair(AF_UNIX,
1262 SOCK_STREAM, 0, config_s) == -1) {
1263 error("reexec socketpair: %s",
1264 strerror(errno));
1265 close(*newsock);
1266 close(startup_p[0]);
1267 close(startup_p[1]);
1268 continue;
1269 }
1270
1271 for (j = 0; j < options.max_startups; j++)
1272 if (startup_pipes[j] == -1) {
1273 startup_pipes[j] = startup_p[0];
1274 if (maxfd < startup_p[0])
1275 maxfd = startup_p[0];
1276 startups++;
1277 break;
1278 }
1279
1280 /*
1281 * Got connection. Fork a child to handle it, unless
1282 * we are in debugging mode.
1283 */
1284 if (debug_flag) {
1285 /*
1286 * In debugging mode. Close the listening
1287 * socket, and start processing the
1288 * connection without forking.
1289 */
1290 debug("Server will not fork when running in debugging mode.");
1291 close_listen_socks();
1292 *sock_in = *newsock;
1293 *sock_out = *newsock;
1294 close(startup_p[0]);
1295 close(startup_p[1]);
1296 startup_pipe = -1;
1297 pid = getpid();
1298 if (rexec_flag) {
1299 send_rexec_state(config_s[0], cfg);
1300 close(config_s[0]);
1301 }
1302 break;
1303 }
1304
1305 /*
1306 * Normal production daemon. Fork, and have
1307 * the child process the connection. The
1308 * parent continues listening.
1309 */
1310 platform_pre_fork();
1311 if ((pid = fork()) == 0) {
1312 /*
1313 * Child. Close the listening and
1314 * max_startup sockets. Start using
1315 * the accepted socket. Reinitialize
1316 * logging (since our pid has changed).
1317 * We break out of the loop to handle
1318 * the connection.
1319 */
1320 platform_post_fork_child();
1321 startup_pipe = startup_p[1];
1322 close_startup_pipes();
1323 close_listen_socks();
1324 *sock_in = *newsock;
1325 *sock_out = *newsock;
1326 log_init(__progname,
1327 options.log_level,
1328 options.log_facility,
1329 log_stderr);
1330 if (rexec_flag)
1331 close(config_s[0]);
1332 break;
1333 }
1334
1335 /* Parent. Stay in the loop. */
1336 platform_post_fork_parent(pid);
1337 if (pid < 0)
1338 error("fork: %.100s", strerror(errno));
1339 else
1340 debug("Forked child %ld.", (long)pid);
1341
1342 close(startup_p[1]);
1343
1344 if (rexec_flag) {
1345 send_rexec_state(config_s[0], cfg);
1346 close(config_s[0]);
1347 close(config_s[1]);
1348 }
1349 close(*newsock);
1350
1351 /*
1352 * Ensure that our random state differs
1353 * from that of the child
1354 */
1355 arc4random_stir();
1356 arc4random_buf(rnd, sizeof(rnd));
1357 #ifdef WITH_OPENSSL
1358 RAND_seed(rnd, sizeof(rnd));
1359 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1360 fatal("%s: RAND_bytes failed", __func__);
1361 #endif
1362 explicit_bzero(rnd, sizeof(rnd));
1363 }
1364
1365 /* child process check (or debug mode) */
1366 if (num_listen_socks < 0)
1367 break;
1368 }
1369 }
1370
1371 /*
1372 * If IP options are supported, make sure there are none (log and
1373 * return an error if any are found). Basically we are worried about
1374 * source routing; it can be used to pretend you are somebody
1375 * (ip-address) you are not. That itself may be "almost acceptable"
1376 * under certain circumstances, but rhosts authentication is useless
1377 * if source routing is accepted. Notice also that if we just dropped
1378 * source routing here, the other side could use IP spoofing to do
1379 * rest of the interaction and could still bypass security. So we
1380 * exit here if we detect any IP options.
1381 */
1382 static void
1383 check_ip_options(struct ssh *ssh)
1384 {
1385 #ifdef IP_OPTIONS
1386 int sock_in = ssh_packet_get_connection_in(ssh);
1387 struct sockaddr_storage from;
1388 u_char opts[200];
1389 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
1390 char text[sizeof(opts) * 3 + 1];
1391
1392 memset(&from, 0, sizeof(from));
1393 if (getpeername(sock_in, (struct sockaddr *)&from,
1394 &fromlen) < 0)
1395 return;
1396 if (from.ss_family != AF_INET)
1397 return;
1398 /* XXX IPv6 options? */
1399
1400 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
1401 &option_size) >= 0 && option_size != 0) {
1402 text[0] = '\0';
1403 for (i = 0; i < option_size; i++)
1404 snprintf(text + i*3, sizeof(text) - i*3,
1405 " %2.2x", opts[i]);
1406 fatal("Connection from %.100s port %d with IP opts: %.800s",
1407 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
1408 }
1409 return;
1410 #endif /* IP_OPTIONS */
1411 }
1412
1413 /* Set the routing domain for this process */
1414 static void
1415 set_process_rdomain(struct ssh *ssh, const char *name)
1416 {
1417 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
1418 if (name == NULL)
1419 return; /* default */
1420
1421 if (strcmp(name, "%D") == 0) {
1422 /* "expands" to routing domain of connection */
1423 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1424 return;
1425 }
1426 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
1427 return sys_set_process_rdomain(name);
1428 #elif defined(__OpenBSD__)
1429 int rtable, ortable = getrtable();
1430 const char *errstr;
1431
1432 if (name == NULL)
1433 return; /* default */
1434
1435 if (strcmp(name, "%D") == 0) {
1436 /* "expands" to routing domain of connection */
1437 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
1438 return;
1439 }
1440
1441 rtable = (int)strtonum(name, 0, 255, &errstr);
1442 if (errstr != NULL) /* Shouldn't happen */
1443 fatal("Invalid routing domain \"%s\": %s", name, errstr);
1444 if (rtable != ortable && setrtable(rtable) != 0)
1445 fatal("Unable to set routing domain %d: %s",
1446 rtable, strerror(errno));
1447 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable);
1448 #else /* defined(__OpenBSD__) */
1449 fatal("Unable to set routing domain: not supported in this platform");
1450 #endif
1451 }
1452
1453 static void
1454 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1455 const struct sshkey *key)
1456 {
1457 static struct ssh_digest_ctx *ctx;
1458 u_char *hash;
1459 size_t len;
1460 struct sshbuf *buf;
1461 int r;
1462
1463 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1464 fatal("%s: ssh_digest_start", __func__);
1465 if (key == NULL) { /* finalize */
1466 /* add server config in case we are using agent for host keys */
1467 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1468 sshbuf_len(server_cfg)) != 0)
1469 fatal("%s: ssh_digest_update", __func__);
1470 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1471 hash = xmalloc(len);
1472 if (ssh_digest_final(ctx, hash, len) != 0)
1473 fatal("%s: ssh_digest_final", __func__);
1474 options.timing_secret = PEEK_U64(hash);
1475 freezero(hash, len);
1476 ssh_digest_free(ctx);
1477 ctx = NULL;
1478 return;
1479 }
1480 if ((buf = sshbuf_new()) == NULL)
1481 fatal("%s could not allocate buffer", __func__);
1482 if ((r = sshkey_private_serialize(key, buf)) != 0)
1483 fatal("sshkey_private_serialize: %s", ssh_err(r));
1484 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1485 fatal("%s: ssh_digest_update", __func__);
1486 sshbuf_reset(buf);
1487 sshbuf_free(buf);
1488 }
1489
1490 /*
1491 * Main program for the daemon.
1492 */
1493 int
1494 main(int ac, char **av)
1495 {
1496 struct ssh *ssh = NULL;
1497 extern char *optarg;
1498 extern int optind;
1499 int r, opt, on = 1, already_daemon, remote_port;
1500 int sock_in = -1, sock_out = -1, newsock = -1;
1501 const char *remote_ip, *rdomain;
1502 char *fp, *line, *laddr, *logfile = NULL;
1503 int config_s[2] = { -1 , -1 };
1504 u_int i, j;
1505 u_int64_t ibytes, obytes;
1506 mode_t new_umask;
1507 struct sshkey *key;
1508 struct sshkey *pubkey;
1509 int keytype;
1510 Authctxt *authctxt;
1511 struct connection_info *connection_info = NULL;
1512
1513 ssh_malloc_init(); /* must be called before any mallocs */
1514
1515 #ifdef HAVE_SECUREWARE
1516 (void)set_auth_parameters(ac, av);
1517 #endif
1518 __progname = ssh_get_progname(av[0]);
1519
1520 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1521 saved_argc = ac;
1522 rexec_argc = ac;
1523 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1524 for (i = 0; (int)i < ac; i++)
1525 saved_argv[i] = xstrdup(av[i]);
1526 saved_argv[i] = NULL;
1527
1528 #ifndef HAVE_SETPROCTITLE
1529 /* Prepare for later setproctitle emulation */
1530 compat_init_setproctitle(ac, av);
1531 av = saved_argv;
1532 #endif
1533
1534 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1535 debug("setgroups(): %.200s", strerror(errno));
1536
1537 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1538 sanitise_stdfd();
1539
1540 /* Initialize configuration options to their default values. */
1541 initialize_server_options(&options);
1542
1543 /* Parse command-line arguments. */
1544 while ((opt = getopt(ac, av,
1545 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) {
1546 switch (opt) {
1547 case '4':
1548 options.address_family = AF_INET;
1549 break;
1550 case '6':
1551 options.address_family = AF_INET6;
1552 break;
1553 case 'f':
1554 config_file_name = optarg;
1555 break;
1556 case 'c':
1557 servconf_add_hostcert("[command-line]", 0,
1558 &options, optarg);
1559 break;
1560 case 'd':
1561 if (debug_flag == 0) {
1562 debug_flag = 1;
1563 options.log_level = SYSLOG_LEVEL_DEBUG1;
1564 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1565 options.log_level++;
1566 break;
1567 case 'D':
1568 no_daemon_flag = 1;
1569 break;
1570 case 'E':
1571 logfile = optarg;
1572 /* FALLTHROUGH */
1573 case 'e':
1574 log_stderr = 1;
1575 break;
1576 case 'i':
1577 inetd_flag = 1;
1578 break;
1579 case 'r':
1580 rexec_flag = 0;
1581 break;
1582 case 'R':
1583 rexeced_flag = 1;
1584 inetd_flag = 1;
1585 break;
1586 case 'Q':
1587 /* ignored */
1588 break;
1589 case 'q':
1590 options.log_level = SYSLOG_LEVEL_QUIET;
1591 break;
1592 case 'b':
1593 /* protocol 1, ignored */
1594 break;
1595 case 'p':
1596 options.ports_from_cmdline = 1;
1597 if (options.num_ports >= MAX_PORTS) {
1598 fprintf(stderr, "too many ports.\n");
1599 exit(1);
1600 }
1601 options.ports[options.num_ports++] = a2port(optarg);
1602 if (options.ports[options.num_ports-1] <= 0) {
1603 fprintf(stderr, "Bad port number.\n");
1604 exit(1);
1605 }
1606 break;
1607 case 'g':
1608 if ((options.login_grace_time = convtime(optarg)) == -1) {
1609 fprintf(stderr, "Invalid login grace time.\n");
1610 exit(1);
1611 }
1612 break;
1613 case 'k':
1614 /* protocol 1, ignored */
1615 break;
1616 case 'h':
1617 servconf_add_hostkey("[command-line]", 0,
1618 &options, optarg);
1619 break;
1620 case 't':
1621 test_flag = 1;
1622 break;
1623 case 'T':
1624 test_flag = 2;
1625 break;
1626 case 'C':
1627 connection_info = get_connection_info(0, 0);
1628 if (parse_server_match_testspec(connection_info,
1629 optarg) == -1)
1630 exit(1);
1631 break;
1632 case 'u':
1633 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1634 if (utmp_len > HOST_NAME_MAX+1) {
1635 fprintf(stderr, "Invalid utmp length.\n");
1636 exit(1);
1637 }
1638 break;
1639 case 'o':
1640 line = xstrdup(optarg);
1641 if (process_server_config_line(&options, line,
1642 "command-line", 0, NULL, NULL) != 0)
1643 exit(1);
1644 free(line);
1645 break;
1646 case '?':
1647 default:
1648 usage();
1649 break;
1650 }
1651 }
1652 if (rexeced_flag || inetd_flag)
1653 rexec_flag = 0;
1654 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1655 fatal("sshd re-exec requires execution with an absolute path");
1656 if (rexeced_flag)
1657 closefrom(REEXEC_MIN_FREE_FD);
1658 else
1659 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1660
1661 #ifdef WITH_OPENSSL
1662 OpenSSL_add_all_algorithms();
1663 #endif
1664
1665 /* If requested, redirect the logs to the specified logfile. */
1666 if (logfile != NULL)
1667 log_redirect_stderr_to(logfile);
1668 /*
1669 * Force logging to stderr until we have loaded the private host
1670 * key (unless started from inetd)
1671 */
1672 log_init(__progname,
1673 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1674 SYSLOG_LEVEL_INFO : options.log_level,
1675 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1676 SYSLOG_FACILITY_AUTH : options.log_facility,
1677 log_stderr || !inetd_flag);
1678
1679 /*
1680 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1681 * root's environment
1682 */
1683 if (getenv("KRB5CCNAME") != NULL)
1684 (void) unsetenv("KRB5CCNAME");
1685
1686 sensitive_data.have_ssh2_key = 0;
1687
1688 /*
1689 * If we're not doing an extended test do not silently ignore connection
1690 * test params.
1691 */
1692 if (test_flag < 2 && connection_info != NULL)
1693 fatal("Config test connection parameter (-C) provided without "
1694 "test mode (-T)");
1695
1696 /* Fetch our configuration */
1697 if ((cfg = sshbuf_new()) == NULL)
1698 fatal("%s: sshbuf_new failed", __func__);
1699 if (rexeced_flag)
1700 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg);
1701 else if (strcasecmp(config_file_name, "none") != 0)
1702 load_server_config(config_file_name, cfg);
1703
1704 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1705 cfg, NULL);
1706
1707 seed_rng();
1708
1709 /* Fill in default values for those options not explicitly set. */
1710 fill_default_server_options(&options);
1711
1712 /* challenge-response is implemented via keyboard interactive */
1713 if (options.challenge_response_authentication)
1714 options.kbd_interactive_authentication = 1;
1715
1716 /* Check that options are sensible */
1717 if (options.authorized_keys_command_user == NULL &&
1718 (options.authorized_keys_command != NULL &&
1719 strcasecmp(options.authorized_keys_command, "none") != 0))
1720 fatal("AuthorizedKeysCommand set without "
1721 "AuthorizedKeysCommandUser");
1722 if (options.authorized_principals_command_user == NULL &&
1723 (options.authorized_principals_command != NULL &&
1724 strcasecmp(options.authorized_principals_command, "none") != 0))
1725 fatal("AuthorizedPrincipalsCommand set without "
1726 "AuthorizedPrincipalsCommandUser");
1727
1728 /*
1729 * Check whether there is any path through configured auth methods.
1730 * Unfortunately it is not possible to verify this generally before
1731 * daemonisation in the presence of Match block, but this catches
1732 * and warns for trivial misconfigurations that could break login.
1733 */
1734 if (options.num_auth_methods != 0) {
1735 for (i = 0; i < options.num_auth_methods; i++) {
1736 if (auth2_methods_valid(options.auth_methods[i],
1737 1) == 0)
1738 break;
1739 }
1740 if (i >= options.num_auth_methods)
1741 fatal("AuthenticationMethods cannot be satisfied by "
1742 "enabled authentication methods");
1743 }
1744
1745 /* Check that there are no remaining arguments. */
1746 if (optind < ac) {
1747 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1748 exit(1);
1749 }
1750
1751 debug("sshd version %s, %s", SSH_VERSION,
1752 #ifdef WITH_OPENSSL
1753 SSLeay_version(SSLEAY_VERSION)
1754 #else
1755 "without OpenSSL"
1756 #endif
1757 );
1758
1759 /* Store privilege separation user for later use if required. */
1760 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0);
1761 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1762 if (privsep_chroot || options.kerberos_authentication)
1763 fatal("Privilege separation user %s does not exist",
1764 SSH_PRIVSEP_USER);
1765 } else {
1766 privsep_pw = pwcopy(privsep_pw);
1767 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1768 privsep_pw->pw_passwd = xstrdup("*");
1769 }
1770 endpwent();
1771
1772 /* load host keys */
1773 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1774 sizeof(struct sshkey *));
1775 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1776 sizeof(struct sshkey *));
1777
1778 if (options.host_key_agent) {
1779 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1780 setenv(SSH_AUTHSOCKET_ENV_NAME,
1781 options.host_key_agent, 1);
1782 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1783 have_agent = 1;
1784 else
1785 error("Could not connect to agent \"%s\": %s",
1786 options.host_key_agent, ssh_err(r));
1787 }
1788
1789 for (i = 0; i < options.num_host_key_files; i++) {
1790 if (options.host_key_files[i] == NULL)
1791 continue;
1792 if ((r = sshkey_load_private(options.host_key_files[i], "",
1793 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1794 error("Error loading host key \"%s\": %s",
1795 options.host_key_files[i], ssh_err(r));
1796 if ((r = sshkey_load_public(options.host_key_files[i],
1797 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1798 error("Error loading host key \"%s\": %s",
1799 options.host_key_files[i], ssh_err(r));
1800 if (pubkey == NULL && key != NULL)
1801 if ((r = sshkey_from_private(key, &pubkey)) != 0)
1802 fatal("Could not demote key: \"%s\": %s",
1803 options.host_key_files[i], ssh_err(r));
1804 sensitive_data.host_keys[i] = key;
1805 sensitive_data.host_pubkeys[i] = pubkey;
1806
1807 if (key == NULL && pubkey != NULL && have_agent) {
1808 debug("will rely on agent for hostkey %s",
1809 options.host_key_files[i]);
1810 keytype = pubkey->type;
1811 } else if (key != NULL) {
1812 keytype = key->type;
1813 accumulate_host_timing_secret(cfg, key);
1814 } else {
1815 error("Could not load host key: %s",
1816 options.host_key_files[i]);
1817 sensitive_data.host_keys[i] = NULL;
1818 sensitive_data.host_pubkeys[i] = NULL;
1819 continue;
1820 }
1821
1822 switch (keytype) {
1823 case KEY_RSA:
1824 case KEY_DSA:
1825 case KEY_ECDSA:
1826 case KEY_ED25519:
1827 case KEY_XMSS:
1828 if (have_agent || key != NULL)
1829 sensitive_data.have_ssh2_key = 1;
1830 break;
1831 }
1832 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1833 SSH_FP_DEFAULT)) == NULL)
1834 fatal("sshkey_fingerprint failed");
1835 debug("%s host key #%d: %s %s",
1836 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1837 free(fp);
1838 }
1839 accumulate_host_timing_secret(cfg, NULL);
1840 if (!sensitive_data.have_ssh2_key) {
1841 logit("sshd: no hostkeys available -- exiting.");
1842 exit(1);
1843 }
1844
1845 /*
1846 * Load certificates. They are stored in an array at identical
1847 * indices to the public keys that they relate to.
1848 */
1849 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1850 sizeof(struct sshkey *));
1851 for (i = 0; i < options.num_host_key_files; i++)
1852 sensitive_data.host_certificates[i] = NULL;
1853
1854 for (i = 0; i < options.num_host_cert_files; i++) {
1855 if (options.host_cert_files[i] == NULL)
1856 continue;
1857 if ((r = sshkey_load_public(options.host_cert_files[i],
1858 &key, NULL)) != 0) {
1859 error("Could not load host certificate \"%s\": %s",
1860 options.host_cert_files[i], ssh_err(r));
1861 continue;
1862 }
1863 if (!sshkey_is_cert(key)) {
1864 error("Certificate file is not a certificate: %s",
1865 options.host_cert_files[i]);
1866 sshkey_free(key);
1867 continue;
1868 }
1869 /* Find matching private key */
1870 for (j = 0; j < options.num_host_key_files; j++) {
1871 if (sshkey_equal_public(key,
1872 sensitive_data.host_keys[j])) {
1873 sensitive_data.host_certificates[j] = key;
1874 break;
1875 }
1876 }
1877 if (j >= options.num_host_key_files) {
1878 error("No matching private key for certificate: %s",
1879 options.host_cert_files[i]);
1880 sshkey_free(key);
1881 continue;
1882 }
1883 sensitive_data.host_certificates[j] = key;
1884 debug("host certificate: #%u type %d %s", j, key->type,
1885 sshkey_type(key));
1886 }
1887
1888 if (privsep_chroot) {
1889 struct stat st;
1890
1891 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1892 (S_ISDIR(st.st_mode) == 0))
1893 fatal("Missing privilege separation directory: %s",
1894 _PATH_PRIVSEP_CHROOT_DIR);
1895
1896 #ifdef HAVE_CYGWIN
1897 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1898 (st.st_uid != getuid () ||
1899 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1900 #else
1901 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1902 #endif
1903 fatal("%s must be owned by root and not group or "
1904 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1905 }
1906
1907 if (test_flag > 1) {
1908 /*
1909 * If no connection info was provided by -C then use
1910 * use a blank one that will cause no predicate to match.
1911 */
1912 if (connection_info == NULL)
1913 connection_info = get_connection_info(0, 0);
1914 parse_server_match_config(&options, connection_info);
1915 dump_config(&options);
1916 }
1917
1918 /* Configuration looks good, so exit if in test mode. */
1919 if (test_flag)
1920 exit(0);
1921
1922 /*
1923 * Clear out any supplemental groups we may have inherited. This
1924 * prevents inadvertent creation of files with bad modes (in the
1925 * portable version at least, it's certainly possible for PAM
1926 * to create a file, and we can't control the code in every
1927 * module which might be used).
1928 */
1929 if (setgroups(0, NULL) < 0)
1930 debug("setgroups() failed: %.200s", strerror(errno));
1931
1932 if (rexec_flag) {
1933 if (rexec_argc < 0)
1934 fatal("rexec_argc %d < 0", rexec_argc);
1935 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1936 for (i = 0; i < (u_int)rexec_argc; i++) {
1937 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1938 rexec_argv[i] = saved_argv[i];
1939 }
1940 rexec_argv[rexec_argc] = "-R";
1941 rexec_argv[rexec_argc + 1] = NULL;
1942 }
1943
1944 /* Ensure that umask disallows at least group and world write */
1945 new_umask = umask(0077) | 0022;
1946 (void) umask(new_umask);
1947
1948 /* Initialize the log (it is reinitialized below in case we forked). */
1949 if (debug_flag && (!inetd_flag || rexeced_flag))
1950 log_stderr = 1;
1951 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1952
1953 /*
1954 * If not in debugging mode, not started from inetd and not already
1955 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1956 * terminal, and fork. The original process exits.
1957 */
1958 already_daemon = daemonized();
1959 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1960
1961 if (daemon(0, 0) < 0)
1962 fatal("daemon() failed: %.200s", strerror(errno));
1963
1964 disconnect_controlling_tty();
1965 }
1966 /* Reinitialize the log (because of the fork above). */
1967 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1968
1969 /* Avoid killing the process in high-pressure swapping environments. */
1970 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0)
1971 debug("madvise(): %.200s", strerror(errno));
1972
1973 /* Chdir to the root directory so that the current disk can be
1974 unmounted if desired. */
1975 if (chdir("/") == -1)
1976 error("chdir(\"/\"): %s", strerror(errno));
1977
1978 /* ignore SIGPIPE */
1979 signal(SIGPIPE, SIG_IGN);
1980
1981 /* Get a connection, either from inetd or a listening TCP socket */
1982 if (inetd_flag) {
1983 server_accept_inetd(&sock_in, &sock_out);
1984 } else {
1985 platform_pre_listen();
1986 server_listen();
1987
1988 signal(SIGHUP, sighup_handler);
1989 signal(SIGCHLD, main_sigchld_handler);
1990 signal(SIGTERM, sigterm_handler);
1991 signal(SIGQUIT, sigterm_handler);
1992
1993 /*
1994 * Write out the pid file after the sigterm handler
1995 * is setup and the listen sockets are bound
1996 */
1997 if (options.pid_file != NULL && !debug_flag) {
1998 FILE *f = fopen(options.pid_file, "w");
1999
2000 if (f == NULL) {
2001 error("Couldn't create pid file \"%s\": %s",
2002 options.pid_file, strerror(errno));
2003 } else {
2004 fprintf(f, "%ld\n", (long) getpid());
2005 fclose(f);
2006 }
2007 }
2008
2009 /* Accept a connection and return in a forked child */
2010 server_accept_loop(&sock_in, &sock_out,
2011 &newsock, config_s);
2012 }
2013
2014 /* This is the child processing a new connection. */
2015 setproctitle("%s", "[accepted]");
2016
2017 /*
2018 * Create a new session and process group since the 4.4BSD
2019 * setlogin() affects the entire process group. We don't
2020 * want the child to be able to affect the parent.
2021 */
2022 #if !defined(SSHD_ACQUIRES_CTTY)
2023 /*
2024 * If setsid is called, on some platforms sshd will later acquire a
2025 * controlling terminal which will result in "could not set
2026 * controlling tty" errors.
2027 */
2028 if (!debug_flag && !inetd_flag && setsid() < 0)
2029 error("setsid: %.100s", strerror(errno));
2030 #endif
2031
2032 if (rexec_flag) {
2033 int fd;
2034
2035 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
2036 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2037 dup2(newsock, STDIN_FILENO);
2038 dup2(STDIN_FILENO, STDOUT_FILENO);
2039 if (startup_pipe == -1)
2040 close(REEXEC_STARTUP_PIPE_FD);
2041 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
2042 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
2043 close(startup_pipe);
2044 startup_pipe = REEXEC_STARTUP_PIPE_FD;
2045 }
2046
2047 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
2048 close(config_s[1]);
2049
2050 execv(rexec_argv[0], rexec_argv);
2051
2052 /* Reexec has failed, fall back and continue */
2053 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
2054 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
2055 log_init(__progname, options.log_level,
2056 options.log_facility, log_stderr);
2057
2058 /* Clean up fds */
2059 close(REEXEC_CONFIG_PASS_FD);
2060 newsock = sock_out = sock_in = dup(STDIN_FILENO);
2061 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
2062 dup2(fd, STDIN_FILENO);
2063 dup2(fd, STDOUT_FILENO);
2064 if (fd > STDERR_FILENO)
2065 close(fd);
2066 }
2067 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
2068 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
2069 }
2070
2071 /* Executed child processes don't need these. */
2072 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
2073 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
2074
2075 /*
2076 * Disable the key regeneration alarm. We will not regenerate the
2077 * key since we are no longer in a position to give it to anyone. We
2078 * will not restart on SIGHUP since it no longer makes sense.
2079 */
2080 alarm(0);
2081 signal(SIGALRM, SIG_DFL);
2082 signal(SIGHUP, SIG_DFL);
2083 signal(SIGTERM, SIG_DFL);
2084 signal(SIGQUIT, SIG_DFL);
2085 signal(SIGCHLD, SIG_DFL);
2086 signal(SIGINT, SIG_DFL);
2087
2088 #ifdef __FreeBSD__
2089 /*
2090 * Initialize the resolver. This may not happen automatically
2091 * before privsep chroot().
2092 */
2093 if ((_res.options & RES_INIT) == 0) {
2094 debug("res_init()");
2095 res_init();
2096 }
2097 #ifdef GSSAPI
2098 /*
2099 * Force GSS-API to parse its configuration and load any
2100 * mechanism plugins.
2101 */
2102 {
2103 gss_OID_set mechs;
2104 OM_uint32 minor_status;
2105 gss_indicate_mechs(&minor_status, &mechs);
2106 gss_release_oid_set(&minor_status, &mechs);
2107 }
2108 #endif
2109 #endif
2110
2111 /*
2112 * Register our connection. This turns encryption off because we do
2113 * not have a key.
2114 */
2115 packet_set_connection(sock_in, sock_out);
2116 packet_set_server();
2117 ssh = active_state; /* XXX */
2118
2119 check_ip_options(ssh);
2120
2121 /* Prepare the channels layer */
2122 channel_init_channels(ssh);
2123 channel_set_af(ssh, options.address_family);
2124 process_permitopen(ssh, &options);
2125
2126 /* Set SO_KEEPALIVE if requested. */
2127 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
2128 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
2129 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
2130
2131 if ((remote_port = ssh_remote_port(ssh)) < 0) {
2132 debug("ssh_remote_port failed");
2133 cleanup_exit(255);
2134 }
2135
2136 if (options.routing_domain != NULL)
2137 set_process_rdomain(ssh, options.routing_domain);
2138
2139 /*
2140 * The rest of the code depends on the fact that
2141 * ssh_remote_ipaddr() caches the remote ip, even if
2142 * the socket goes away.
2143 */
2144 remote_ip = ssh_remote_ipaddr(ssh);
2145
2146 #ifdef HAVE_LOGIN_CAP
2147 /* Also caches remote hostname for sandboxed child. */
2148 auth_get_canonical_hostname(ssh, options.use_dns);
2149 #endif
2150
2151 #ifdef SSH_AUDIT_EVENTS
2152 audit_connection_from(remote_ip, remote_port);
2153 #endif
2154 #ifdef LIBWRAP
2155 allow_severity = options.log_facility|LOG_INFO;
2156 deny_severity = options.log_facility|LOG_WARNING;
2157 /* Check whether logins are denied from this host. */
2158 if (packet_connection_is_on_socket()) {
2159 struct request_info req;
2160
2161 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
2162 fromhost(&req);
2163
2164 if (!hosts_access(&req)) {
2165 debug("Connection refused by tcp wrapper");
2166 refuse(&req);
2167 /* NOTREACHED */
2168 fatal("libwrap refuse returns");
2169 }
2170 }
2171 #endif /* LIBWRAP */
2172
2173 rdomain = ssh_packet_rdomain_in(ssh);
2174
2175 /* Log the connection. */
2176 laddr = get_local_ipaddr(sock_in);
2177 verbose("Connection from %s port %d on %s port %d%s%s%s",
2178 remote_ip, remote_port, laddr, ssh_local_port(ssh),
2179 rdomain == NULL ? "" : " rdomain \"",
2180 rdomain == NULL ? "" : rdomain,
2181 rdomain == NULL ? "" : "\"");
2182 free(laddr);
2183
2184 /*
2185 * We don't want to listen forever unless the other side
2186 * successfully authenticates itself. So we set up an alarm which is
2187 * cleared after successful authentication. A limit of zero
2188 * indicates no limit. Note that we don't set the alarm in debugging
2189 * mode; it is just annoying to have the server exit just when you
2190 * are about to discover the bug.
2191 */
2192 signal(SIGALRM, grace_alarm_handler);
2193 if (!debug_flag)
2194 alarm(options.login_grace_time);
2195
2196 sshd_exchange_identification(ssh, sock_in, sock_out);
2197 packet_set_nonblocking();
2198
2199 /* allocate authentication context */
2200 authctxt = xcalloc(1, sizeof(*authctxt));
2201
2202 authctxt->loginmsg = loginmsg;
2203
2204 /* XXX global for cleanup, access from other modules */
2205 the_authctxt = authctxt;
2206
2207 /* Set default key authentication options */
2208 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
2209 fatal("allocation failed");
2210
2211 /* prepare buffer to collect messages to display to user after login */
2212 if ((loginmsg = sshbuf_new()) == NULL)
2213 fatal("%s: sshbuf_new failed", __func__);
2214 auth_debug_reset();
2215
2216 BLACKLIST_INIT();
2217
2218 if (use_privsep) {
2219 if (privsep_preauth(authctxt) == 1)
2220 goto authenticated;
2221 } else if (have_agent) {
2222 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
2223 error("Unable to get agent socket: %s", ssh_err(r));
2224 have_agent = 0;
2225 }
2226 }
2227
2228 /* perform the key exchange */
2229 /* authenticate user and start session */
2230 do_ssh2_kex();
2231 do_authentication2(authctxt);
2232
2233 /*
2234 * If we use privilege separation, the unprivileged child transfers
2235 * the current keystate and exits
2236 */
2237 if (use_privsep) {
2238 mm_send_keystate(pmonitor);
2239 packet_clear_keys();
2240 exit(0);
2241 }
2242
2243 authenticated:
2244 /*
2245 * Cancel the alarm we set to limit the time taken for
2246 * authentication.
2247 */
2248 alarm(0);
2249 signal(SIGALRM, SIG_DFL);
2250 authctxt->authenticated = 1;
2251 if (startup_pipe != -1) {
2252 close(startup_pipe);
2253 startup_pipe = -1;
2254 }
2255
2256 #ifdef SSH_AUDIT_EVENTS
2257 audit_event(SSH_AUTH_SUCCESS);
2258 #endif
2259
2260 #ifdef GSSAPI
2261 if (options.gss_authentication) {
2262 temporarily_use_uid(authctxt->pw);
2263 ssh_gssapi_storecreds();
2264 restore_uid();
2265 }
2266 #endif
2267 #ifdef USE_PAM
2268 if (options.use_pam) {
2269 do_pam_setcred(1);
2270 do_pam_session(ssh);
2271 }
2272 #endif
2273
2274 /*
2275 * In privilege separation, we fork another child and prepare
2276 * file descriptor passing.
2277 */
2278 if (use_privsep) {
2279 privsep_postauth(authctxt);
2280 /* the monitor process [priv] will not return */
2281 }
2282
2283 packet_set_timeout(options.client_alive_interval,
2284 options.client_alive_count_max);
2285
2286 /* Try to send all our hostkeys to the client */
2287 notify_hostkeys(ssh);
2288
2289 /* Start session. */
2290 do_authenticated(ssh, authctxt);
2291
2292 /* The connection has been terminated. */
2293 packet_get_bytes(&ibytes, &obytes);
2294 verbose("Transferred: sent %llu, received %llu bytes",
2295 (unsigned long long)obytes, (unsigned long long)ibytes);
2296
2297 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2298
2299 #ifdef USE_PAM
2300 if (options.use_pam)
2301 finish_pam();
2302 #endif /* USE_PAM */
2303
2304 #ifdef SSH_AUDIT_EVENTS
2305 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2306 #endif
2307
2308 packet_close();
2309
2310 if (use_privsep)
2311 mm_terminate();
2312
2313 exit(0);
2314 }
2315
2316 int
2317 sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey,
2318 u_char **signature, size_t *slenp, const u_char *data, size_t dlen,
2319 const char *alg, u_int flag)
2320 {
2321 int r;
2322
2323 if (privkey) {
2324 if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen,
2325 alg, datafellows)) < 0)
2326 fatal("%s: key_sign failed", __func__);
2327 } else if (use_privsep) {
2328 if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen,
2329 alg, datafellows) < 0)
2330 fatal("%s: pubkey_sign failed", __func__);
2331 } else {
2332 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp,
2333 data, dlen, alg, datafellows)) != 0)
2334 fatal("%s: ssh_agent_sign failed: %s",
2335 __func__, ssh_err(r));
2336 }
2337 return 0;
2338 }
2339
2340 /* SSH2 key exchange */
2341 static void
2342 do_ssh2_kex(void)
2343 {
2344 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER };
2345 struct kex *kex;
2346 int r;
2347
2348 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
2349 options.kex_algorithms);
2350 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(
2351 options.ciphers);
2352 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(
2353 options.ciphers);
2354 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2355 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2356
2357 if (options.compression == COMP_NONE) {
2358 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2359 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2360 }
2361
2362 if (options.rekey_limit || options.rekey_interval)
2363 packet_set_rekey_limits(options.rekey_limit,
2364 options.rekey_interval);
2365
2366 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal(
2367 list_hostkey_types());
2368
2369 /* start key exchange */
2370 if ((r = kex_setup(active_state, myproposal)) != 0)
2371 fatal("kex_setup: %s", ssh_err(r));
2372 kex = active_state->kex;
2373 #ifdef WITH_OPENSSL
2374 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2375 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2376 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server;
2377 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server;
2378 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server;
2379 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2380 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2381 # ifdef OPENSSL_HAS_ECC
2382 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2383 # endif
2384 #endif
2385 kex->kex[KEX_C25519_SHA256] = kexc25519_server;
2386 kex->server = 1;
2387 kex->client_version_string=client_version_string;
2388 kex->server_version_string=server_version_string;
2389 kex->load_host_public_key=&get_hostkey_public_by_type;
2390 kex->load_host_private_key=&get_hostkey_private_by_type;
2391 kex->host_key_index=&get_hostkey_index;
2392 kex->sign = sshd_hostkey_sign;
2393
2394 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
2395
2396 session_id2 = kex->session_id;
2397 session_id2_len = kex->session_id_len;
2398
2399 #ifdef DEBUG_KEXDH
2400 /* send 1st encrypted/maced/compressed message */
2401 packet_start(SSH2_MSG_IGNORE);
2402 packet_put_cstring("markus");
2403 packet_send();
2404 packet_write_wait();
2405 #endif
2406 debug("KEX done");
2407 }
2408
2409 /* server specific fatal cleanup */
2410 void
2411 cleanup_exit(int i)
2412 {
2413 struct ssh *ssh = active_state; /* XXX */
2414
2415 if (the_authctxt) {
2416 do_cleanup(ssh, the_authctxt);
2417 if (use_privsep && privsep_is_preauth &&
2418 pmonitor != NULL && pmonitor->m_pid > 1) {
2419 debug("Killing privsep child %d", pmonitor->m_pid);
2420 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
2421 errno != ESRCH)
2422 error("%s: kill(%d): %s", __func__,
2423 pmonitor->m_pid, strerror(errno));
2424 }
2425 }
2426 #ifdef SSH_AUDIT_EVENTS
2427 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2428 if (!use_privsep || mm_is_monitor())
2429 audit_event(SSH_CONNECTION_ABANDON);
2430 #endif
2431 _exit(i);
2432 }
2433