1 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 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
75 #include <openssl/dh.h>
76 #include <openssl/bn.h>
77 #include <openssl/md5.h>
78 #include <openssl/rand.h>
79 #include "openbsd-compat/openssl-compat.h"
80
81 #ifdef HAVE_SECUREWARE
82 #include <sys/security.h>
83 #include <prot.h>
84 #endif
85
86 #include "xmalloc.h"
87 #include "ssh.h"
88 #include "ssh1.h"
89 #include "ssh2.h"
90 #include "rsa.h"
91 #include "sshpty.h"
92 #include "packet.h"
93 #include "log.h"
94 #include "buffer.h"
95 #include "servconf.h"
96 #include "uidswap.h"
97 #include "compat.h"
98 #include "cipher.h"
99 #include "key.h"
100 #include "kex.h"
101 #include "dh.h"
102 #include "myproposal.h"
103 #include "authfile.h"
104 #include "pathnames.h"
105 #include "atomicio.h"
106 #include "canohost.h"
107 #include "hostfile.h"
108 #include "auth.h"
109 #include "misc.h"
110 #include "msg.h"
111 #include "dispatch.h"
112 #include "channels.h"
113 #include "session.h"
114 #include "monitor_mm.h"
115 #include "monitor.h"
116 #ifdef GSSAPI
117 #include "ssh-gss.h"
118 #endif
119 #include "monitor_wrap.h"
120 #include "roaming.h"
121 #include "ssh-sandbox.h"
122 #include "version.h"
123
124 #ifdef LIBWRAP
125 #include <tcpd.h>
126 #include <syslog.h>
127 int allow_severity;
128 int deny_severity;
129 #endif /* LIBWRAP */
130
131 #ifndef O_NOCTTY
132 #define O_NOCTTY 0
133 #endif
134
135 /* Re-exec fds */
136 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
137 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
138 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
139 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
140
141 extern char *__progname;
142
143 /* Server configuration options. */
144 ServerOptions options;
145
146 /* Name of the server configuration file. */
147 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
148
149 /*
150 * Debug mode flag. This can be set on the command line. If debug
151 * mode is enabled, extra debugging output will be sent to the system
152 * log, the daemon will not go to background, and will exit after processing
153 * the first connection.
154 */
155 int debug_flag = 0;
156
157 /* Flag indicating that the daemon should only test the configuration and keys. */
158 int test_flag = 0;
159
160 /* Flag indicating that the daemon is being started from inetd. */
161 int inetd_flag = 0;
162
163 /* Flag indicating that sshd should not detach and become a daemon. */
164 int no_daemon_flag = 0;
165
166 /* debug goes to stderr unless inetd_flag is set */
167 int log_stderr = 0;
168
169 /* Saved arguments to main(). */
170 char **saved_argv;
171 int saved_argc;
172
173 /* re-exec */
174 int rexeced_flag = 0;
175 int rexec_flag = 1;
176 int rexec_argc = 0;
177 char **rexec_argv;
178
179 /*
180 * The sockets that the server is listening; this is used in the SIGHUP
181 * signal handler.
182 */
183 #define MAX_LISTEN_SOCKS 16
184 int listen_socks[MAX_LISTEN_SOCKS];
185 int num_listen_socks = 0;
186
187 /*
188 * the client's version string, passed by sshd2 in compat mode. if != NULL,
189 * sshd will skip the version-number exchange
190 */
191 char *client_version_string = NULL;
192 char *server_version_string = NULL;
193
194 /* for rekeying XXX fixme */
195 Kex *xxx_kex;
196
197 /*
198 * Any really sensitive data in the application is contained in this
199 * structure. The idea is that this structure could be locked into memory so
200 * that the pages do not get written into swap. However, there are some
201 * problems. The private key contains BIGNUMs, and we do not (in principle)
202 * have access to the internals of them, and locking just the structure is
203 * not very useful. Currently, memory locking is not implemented.
204 */
205 struct {
206 Key *server_key; /* ephemeral server key */
207 Key *ssh1_host_key; /* ssh1 host key */
208 Key **host_keys; /* all private host keys */
209 Key **host_certificates; /* all public host certificates */
210 int have_ssh1_key;
211 int have_ssh2_key;
212 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
213 } sensitive_data;
214
215 /*
216 * Flag indicating whether the RSA server key needs to be regenerated.
217 * Is set in the SIGALRM handler and cleared when the key is regenerated.
218 */
219 static volatile sig_atomic_t key_do_regen = 0;
220
221 /* This is set to true when a signal is received. */
222 static volatile sig_atomic_t received_sighup = 0;
223 static volatile sig_atomic_t received_sigterm = 0;
224
225 /* session identifier, used by RSA-auth */
226 u_char session_id[16];
227
228 /* same for ssh2 */
229 u_char *session_id2 = NULL;
230 u_int session_id2_len = 0;
231
232 /* record remote hostname or ip */
233 u_int utmp_len = MAXHOSTNAMELEN;
234
235 /* options.max_startup sized array of fd ints */
236 int *startup_pipes = NULL;
237 int startup_pipe; /* in child */
238
239 /* variables used for privilege separation */
240 int use_privsep = -1;
241 struct monitor *pmonitor = NULL;
242
243 /* global authentication context */
244 Authctxt *the_authctxt = NULL;
245
246 /* sshd_config buffer */
247 Buffer cfg;
248
249 /* message to be displayed after login */
250 Buffer loginmsg;
251
252 /* Unprivileged user */
253 struct passwd *privsep_pw = NULL;
254
255 /* Prototypes for various functions defined later in this file. */
256 void destroy_sensitive_data(void);
257 void demote_sensitive_data(void);
258
259 static void do_ssh1_kex(void);
260 static void do_ssh2_kex(void);
261
262 /*
263 * Close all listening sockets
264 */
265 static void
close_listen_socks(void)266 close_listen_socks(void)
267 {
268 int i;
269
270 for (i = 0; i < num_listen_socks; i++)
271 close(listen_socks[i]);
272 num_listen_socks = -1;
273 }
274
275 static void
close_startup_pipes(void)276 close_startup_pipes(void)
277 {
278 int i;
279
280 if (startup_pipes)
281 for (i = 0; i < options.max_startups; i++)
282 if (startup_pipes[i] != -1)
283 close(startup_pipes[i]);
284 }
285
286 /*
287 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
288 * the effect is to reread the configuration file (and to regenerate
289 * the server key).
290 */
291
292 /*ARGSUSED*/
293 static void
sighup_handler(int sig)294 sighup_handler(int sig)
295 {
296 int save_errno = errno;
297
298 received_sighup = 1;
299 signal(SIGHUP, sighup_handler);
300 errno = save_errno;
301 }
302
303 /*
304 * Called from the main program after receiving SIGHUP.
305 * Restarts the server.
306 */
307 static void
sighup_restart(void)308 sighup_restart(void)
309 {
310 logit("Received SIGHUP; restarting.");
311 close_listen_socks();
312 close_startup_pipes();
313 alarm(0); /* alarm timer persists across exec */
314 signal(SIGHUP, SIG_IGN); /* will be restored after exec */
315 execv(saved_argv[0], saved_argv);
316 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
317 strerror(errno));
318 exit(1);
319 }
320
321 /*
322 * Generic signal handler for terminating signals in the master daemon.
323 */
324 /*ARGSUSED*/
325 static void
sigterm_handler(int sig)326 sigterm_handler(int sig)
327 {
328 received_sigterm = sig;
329 }
330
331 /*
332 * SIGCHLD handler. This is called whenever a child dies. This will then
333 * reap any zombies left by exited children.
334 */
335 /*ARGSUSED*/
336 static void
main_sigchld_handler(int sig)337 main_sigchld_handler(int sig)
338 {
339 int save_errno = errno;
340 pid_t pid;
341 int status;
342
343 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
344 (pid < 0 && errno == EINTR))
345 ;
346
347 signal(SIGCHLD, main_sigchld_handler);
348 errno = save_errno;
349 }
350
351 /*
352 * Signal handler for the alarm after the login grace period has expired.
353 */
354 /*ARGSUSED*/
355 static void
grace_alarm_handler(int sig)356 grace_alarm_handler(int sig)
357 {
358 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
359 kill(pmonitor->m_pid, SIGALRM);
360
361 /* Log error and exit. */
362 sigdie("Timeout before authentication for %s", get_remote_ipaddr());
363 }
364
365 /*
366 * Signal handler for the key regeneration alarm. Note that this
367 * alarm only occurs in the daemon waiting for connections, and it does not
368 * do anything with the private key or random state before forking.
369 * Thus there should be no concurrency control/asynchronous execution
370 * problems.
371 */
372 static void
generate_ephemeral_server_key(void)373 generate_ephemeral_server_key(void)
374 {
375 verbose("Generating %s%d bit RSA key.",
376 sensitive_data.server_key ? "new " : "", options.server_key_bits);
377 if (sensitive_data.server_key != NULL)
378 key_free(sensitive_data.server_key);
379 sensitive_data.server_key = key_generate(KEY_RSA1,
380 options.server_key_bits);
381 verbose("RSA key generation complete.");
382
383 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
384 arc4random_stir();
385 }
386
387 /*ARGSUSED*/
388 static void
key_regeneration_alarm(int sig)389 key_regeneration_alarm(int sig)
390 {
391 int save_errno = errno;
392
393 signal(SIGALRM, SIG_DFL);
394 errno = save_errno;
395 key_do_regen = 1;
396 }
397
398 static void
sshd_exchange_identification(int sock_in,int sock_out)399 sshd_exchange_identification(int sock_in, int sock_out)
400 {
401 u_int i;
402 int mismatch;
403 int remote_major, remote_minor;
404 int major, minor;
405 char *s, *newline = "\n";
406 char buf[256]; /* Must not be larger than remote_version. */
407 char remote_version[256]; /* Must be at least as big as buf. */
408
409 if ((options.protocol & SSH_PROTO_1) &&
410 (options.protocol & SSH_PROTO_2)) {
411 major = PROTOCOL_MAJOR_1;
412 minor = 99;
413 } else if (options.protocol & SSH_PROTO_2) {
414 major = PROTOCOL_MAJOR_2;
415 minor = PROTOCOL_MINOR_2;
416 newline = "\r\n";
417 } else {
418 major = PROTOCOL_MAJOR_1;
419 minor = PROTOCOL_MINOR_1;
420 }
421 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
422 SSH_VERSION, newline);
423 server_version_string = xstrdup(buf);
424
425 /* Send our protocol version identification. */
426 if (roaming_atomicio(vwrite, sock_out, server_version_string,
427 strlen(server_version_string))
428 != strlen(server_version_string)) {
429 logit("Could not write ident string to %s", get_remote_ipaddr());
430 cleanup_exit(255);
431 }
432
433 /* Read other sides version identification. */
434 memset(buf, 0, sizeof(buf));
435 for (i = 0; i < sizeof(buf) - 1; i++) {
436 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
437 logit("Did not receive identification string from %s",
438 get_remote_ipaddr());
439 cleanup_exit(255);
440 }
441 if (buf[i] == '\r') {
442 buf[i] = 0;
443 /* Kludge for F-Secure Macintosh < 1.0.2 */
444 if (i == 12 &&
445 strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
446 break;
447 continue;
448 }
449 if (buf[i] == '\n') {
450 buf[i] = 0;
451 break;
452 }
453 }
454 buf[sizeof(buf) - 1] = 0;
455 client_version_string = xstrdup(buf);
456
457 /*
458 * Check that the versions match. In future this might accept
459 * several versions and set appropriate flags to handle them.
460 */
461 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
462 &remote_major, &remote_minor, remote_version) != 3) {
463 s = "Protocol mismatch.\n";
464 (void) atomicio(vwrite, sock_out, s, strlen(s));
465 close(sock_in);
466 close(sock_out);
467 logit("Bad protocol version identification '%.100s' from %s",
468 client_version_string, get_remote_ipaddr());
469 cleanup_exit(255);
470 }
471 debug("Client protocol version %d.%d; client software version %.100s",
472 remote_major, remote_minor, remote_version);
473
474 compat_datafellows(remote_version);
475
476 if (datafellows & SSH_BUG_PROBE) {
477 logit("probed from %s with %s. Don't panic.",
478 get_remote_ipaddr(), client_version_string);
479 cleanup_exit(255);
480 }
481
482 if (datafellows & SSH_BUG_SCANNER) {
483 logit("scanned from %s with %s. Don't panic.",
484 get_remote_ipaddr(), client_version_string);
485 cleanup_exit(255);
486 }
487
488 mismatch = 0;
489 switch (remote_major) {
490 case 1:
491 if (remote_minor == 99) {
492 if (options.protocol & SSH_PROTO_2)
493 enable_compat20();
494 else
495 mismatch = 1;
496 break;
497 }
498 if (!(options.protocol & SSH_PROTO_1)) {
499 mismatch = 1;
500 break;
501 }
502 if (remote_minor < 3) {
503 packet_disconnect("Your ssh version is too old and "
504 "is no longer supported. Please install a newer version.");
505 } else if (remote_minor == 3) {
506 /* note that this disables agent-forwarding */
507 enable_compat13();
508 }
509 break;
510 case 2:
511 if (options.protocol & SSH_PROTO_2) {
512 enable_compat20();
513 break;
514 }
515 /* FALLTHROUGH */
516 default:
517 mismatch = 1;
518 break;
519 }
520 chop(server_version_string);
521 debug("Local version string %.200s", server_version_string);
522
523 if (mismatch) {
524 s = "Protocol major versions differ.\n";
525 (void) atomicio(vwrite, sock_out, s, strlen(s));
526 close(sock_in);
527 close(sock_out);
528 logit("Protocol major versions differ for %s: %.200s vs. %.200s",
529 get_remote_ipaddr(),
530 server_version_string, client_version_string);
531 cleanup_exit(255);
532 }
533 }
534
535 /* Destroy the host and server keys. They will no longer be needed. */
536 void
destroy_sensitive_data(void)537 destroy_sensitive_data(void)
538 {
539 int i;
540
541 if (sensitive_data.server_key) {
542 key_free(sensitive_data.server_key);
543 sensitive_data.server_key = NULL;
544 }
545 for (i = 0; i < options.num_host_key_files; i++) {
546 if (sensitive_data.host_keys[i]) {
547 key_free(sensitive_data.host_keys[i]);
548 sensitive_data.host_keys[i] = NULL;
549 }
550 if (sensitive_data.host_certificates[i]) {
551 key_free(sensitive_data.host_certificates[i]);
552 sensitive_data.host_certificates[i] = NULL;
553 }
554 }
555 sensitive_data.ssh1_host_key = NULL;
556 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
557 }
558
559 /* Demote private to public keys for network child */
560 void
demote_sensitive_data(void)561 demote_sensitive_data(void)
562 {
563 Key *tmp;
564 int i;
565
566 if (sensitive_data.server_key) {
567 tmp = key_demote(sensitive_data.server_key);
568 key_free(sensitive_data.server_key);
569 sensitive_data.server_key = tmp;
570 }
571
572 for (i = 0; i < options.num_host_key_files; i++) {
573 if (sensitive_data.host_keys[i]) {
574 tmp = key_demote(sensitive_data.host_keys[i]);
575 key_free(sensitive_data.host_keys[i]);
576 sensitive_data.host_keys[i] = tmp;
577 if (tmp->type == KEY_RSA1)
578 sensitive_data.ssh1_host_key = tmp;
579 }
580 /* Certs do not need demotion */
581 }
582
583 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
584 }
585
586 static void
privsep_preauth_child(void)587 privsep_preauth_child(void)
588 {
589 u_int32_t rnd[256];
590 gid_t gidset[1];
591
592 /* Enable challenge-response authentication for privilege separation */
593 privsep_challenge_enable();
594
595 arc4random_stir();
596 arc4random_buf(rnd, sizeof(rnd));
597 RAND_seed(rnd, sizeof(rnd));
598
599 /* Demote the private keys to public keys. */
600 demote_sensitive_data();
601
602 /* Change our root directory */
603 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
604 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
605 strerror(errno));
606 if (chdir("/") == -1)
607 fatal("chdir(\"/\"): %s", strerror(errno));
608
609 /* Drop our privileges */
610 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
611 (u_int)privsep_pw->pw_gid);
612 #if 0
613 /* XXX not ready, too heavy after chroot */
614 do_setusercontext(privsep_pw);
615 #else
616 gidset[0] = privsep_pw->pw_gid;
617 if (setgroups(1, gidset) < 0)
618 fatal("setgroups: %.100s", strerror(errno));
619 permanently_set_uid(privsep_pw);
620 #endif
621 }
622
623 static int
privsep_preauth(Authctxt * authctxt)624 privsep_preauth(Authctxt *authctxt)
625 {
626 int status;
627 pid_t pid;
628 struct ssh_sandbox *box = NULL;
629
630 /* Set up unprivileged child process to deal with network data */
631 pmonitor = monitor_init();
632 /* Store a pointer to the kex for later rekeying */
633 pmonitor->m_pkex = &xxx_kex;
634
635 if (use_privsep == PRIVSEP_SANDBOX)
636 box = ssh_sandbox_init();
637 pid = fork();
638 if (pid == -1) {
639 fatal("fork of unprivileged child failed");
640 } else if (pid != 0) {
641 debug2("Network child is on pid %ld", (long)pid);
642
643 if (box != NULL)
644 ssh_sandbox_parent_preauth(box, pid);
645 pmonitor->m_pid = pid;
646 monitor_child_preauth(authctxt, pmonitor);
647
648 /* Sync memory */
649 monitor_sync(pmonitor);
650
651 /* Wait for the child's exit status */
652 while (waitpid(pid, &status, 0) < 0) {
653 if (errno != EINTR)
654 fatal("%s: waitpid: %s", __func__,
655 strerror(errno));
656 }
657 if (WIFEXITED(status)) {
658 if (WEXITSTATUS(status) != 0)
659 fatal("%s: preauth child exited with status %d",
660 __func__, WEXITSTATUS(status));
661 } else if (WIFSIGNALED(status))
662 fatal("%s: preauth child terminated by signal %d",
663 __func__, WTERMSIG(status));
664 if (box != NULL)
665 ssh_sandbox_parent_finish(box);
666 return 1;
667 } else {
668 /* child */
669 close(pmonitor->m_sendfd);
670 close(pmonitor->m_log_recvfd);
671
672 /* Arrange for logging to be sent to the monitor */
673 set_log_handler(mm_log_handler, pmonitor);
674
675 /* Demote the child */
676 if (getuid() == 0 || geteuid() == 0)
677 privsep_preauth_child();
678 setproctitle("%s", "[net]");
679 if (box != NULL)
680 ssh_sandbox_child(box);
681
682 return 0;
683 }
684 }
685
686 static void
privsep_postauth(Authctxt * authctxt)687 privsep_postauth(Authctxt *authctxt)
688 {
689 u_int32_t rnd[256];
690
691 #ifdef DISABLE_FD_PASSING
692 if (1) {
693 #else
694 if (authctxt->pw->pw_uid == 0 || options.use_login) {
695 #endif
696 /* File descriptor passing is broken or root login */
697 use_privsep = 0;
698 goto skip;
699 }
700
701 /* New socket pair */
702 monitor_reinit(pmonitor);
703
704 pmonitor->m_pid = fork();
705 if (pmonitor->m_pid == -1)
706 fatal("fork of unprivileged child failed");
707 else if (pmonitor->m_pid != 0) {
708 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
709 buffer_clear(&loginmsg);
710 monitor_child_postauth(pmonitor);
711
712 /* NEVERREACHED */
713 exit(0);
714 }
715
716 /* child */
717
718 close(pmonitor->m_sendfd);
719 pmonitor->m_sendfd = -1;
720
721 /* Demote the private keys to public keys. */
722 demote_sensitive_data();
723
724 arc4random_stir();
725 arc4random_buf(rnd, sizeof(rnd));
726 RAND_seed(rnd, sizeof(rnd));
727
728 /* Drop privileges */
729 do_setusercontext(authctxt->pw);
730
731 skip:
732 /* It is safe now to apply the key state */
733 monitor_apply_keystate(pmonitor);
734
735 /*
736 * Tell the packet layer that authentication was successful, since
737 * this information is not part of the key state.
738 */
739 packet_set_authenticated();
740 }
741
742 static char *
743 list_hostkey_types(void)
744 {
745 Buffer b;
746 const char *p;
747 char *ret;
748 int i;
749 Key *key;
750
751 buffer_init(&b);
752 for (i = 0; i < options.num_host_key_files; i++) {
753 key = sensitive_data.host_keys[i];
754 if (key == NULL)
755 continue;
756 switch (key->type) {
757 case KEY_RSA:
758 case KEY_DSA:
759 case KEY_ECDSA:
760 if (buffer_len(&b) > 0)
761 buffer_append(&b, ",", 1);
762 p = key_ssh_name(key);
763 buffer_append(&b, p, strlen(p));
764 break;
765 }
766 /* If the private key has a cert peer, then list that too */
767 key = sensitive_data.host_certificates[i];
768 if (key == NULL)
769 continue;
770 switch (key->type) {
771 case KEY_RSA_CERT_V00:
772 case KEY_DSA_CERT_V00:
773 case KEY_RSA_CERT:
774 case KEY_DSA_CERT:
775 case KEY_ECDSA_CERT:
776 if (buffer_len(&b) > 0)
777 buffer_append(&b, ",", 1);
778 p = key_ssh_name(key);
779 buffer_append(&b, p, strlen(p));
780 break;
781 }
782 }
783 buffer_append(&b, "\0", 1);
784 ret = xstrdup(buffer_ptr(&b));
785 buffer_free(&b);
786 debug("list_hostkey_types: %s", ret);
787 return ret;
788 }
789
790 static Key *
791 get_hostkey_by_type(int type, int need_private)
792 {
793 int i;
794 Key *key;
795
796 for (i = 0; i < options.num_host_key_files; i++) {
797 switch (type) {
798 case KEY_RSA_CERT_V00:
799 case KEY_DSA_CERT_V00:
800 case KEY_RSA_CERT:
801 case KEY_DSA_CERT:
802 case KEY_ECDSA_CERT:
803 key = sensitive_data.host_certificates[i];
804 break;
805 default:
806 key = sensitive_data.host_keys[i];
807 break;
808 }
809 if (key != NULL && key->type == type)
810 return need_private ?
811 sensitive_data.host_keys[i] : key;
812 }
813 return NULL;
814 }
815
816 Key *
817 get_hostkey_public_by_type(int type)
818 {
819 return get_hostkey_by_type(type, 0);
820 }
821
822 Key *
823 get_hostkey_private_by_type(int type)
824 {
825 return get_hostkey_by_type(type, 1);
826 }
827
828 Key *
829 get_hostkey_by_index(int ind)
830 {
831 if (ind < 0 || ind >= options.num_host_key_files)
832 return (NULL);
833 return (sensitive_data.host_keys[ind]);
834 }
835
836 int
837 get_hostkey_index(Key *key)
838 {
839 int i;
840
841 for (i = 0; i < options.num_host_key_files; i++) {
842 if (key_is_cert(key)) {
843 if (key == sensitive_data.host_certificates[i])
844 return (i);
845 } else {
846 if (key == sensitive_data.host_keys[i])
847 return (i);
848 }
849 }
850 return (-1);
851 }
852
853 /*
854 * returns 1 if connection should be dropped, 0 otherwise.
855 * dropping starts at connection #max_startups_begin with a probability
856 * of (max_startups_rate/100). the probability increases linearly until
857 * all connections are dropped for startups > max_startups
858 */
859 static int
860 drop_connection(int startups)
861 {
862 int p, r;
863
864 if (startups < options.max_startups_begin)
865 return 0;
866 if (startups >= options.max_startups)
867 return 1;
868 if (options.max_startups_rate == 100)
869 return 1;
870
871 p = 100 - options.max_startups_rate;
872 p *= startups - options.max_startups_begin;
873 p /= options.max_startups - options.max_startups_begin;
874 p += options.max_startups_rate;
875 r = arc4random_uniform(100);
876
877 debug("drop_connection: p %d, r %d", p, r);
878 return (r < p) ? 1 : 0;
879 }
880
881 static void
882 usage(void)
883 {
884 fprintf(stderr, "%s, %s\n",
885 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION));
886 fprintf(stderr,
887 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n"
888 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n"
889 " [-k key_gen_time] [-o option] [-p port] [-u len]\n"
890 );
891 exit(1);
892 }
893
894 static void
895 send_rexec_state(int fd, Buffer *conf)
896 {
897 Buffer m;
898
899 debug3("%s: entering fd = %d config len %d", __func__, fd,
900 buffer_len(conf));
901
902 /*
903 * Protocol from reexec master to child:
904 * string configuration
905 * u_int ephemeral_key_follows
906 * bignum e (only if ephemeral_key_follows == 1)
907 * bignum n "
908 * bignum d "
909 * bignum iqmp "
910 * bignum p "
911 * bignum q "
912 * string rngseed (only if OpenSSL is not self-seeded)
913 */
914 buffer_init(&m);
915 buffer_put_cstring(&m, buffer_ptr(conf));
916
917 if (sensitive_data.server_key != NULL &&
918 sensitive_data.server_key->type == KEY_RSA1) {
919 buffer_put_int(&m, 1);
920 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
921 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
922 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
923 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
924 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
925 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
926 } else
927 buffer_put_int(&m, 0);
928
929 #ifndef OPENSSL_PRNG_ONLY
930 rexec_send_rng_seed(&m);
931 #endif
932
933 if (ssh_msg_send(fd, 0, &m) == -1)
934 fatal("%s: ssh_msg_send failed", __func__);
935
936 buffer_free(&m);
937
938 debug3("%s: done", __func__);
939 }
940
941 static void
942 recv_rexec_state(int fd, Buffer *conf)
943 {
944 Buffer m;
945 char *cp;
946 u_int len;
947
948 debug3("%s: entering fd = %d", __func__, fd);
949
950 buffer_init(&m);
951
952 if (ssh_msg_recv(fd, &m) == -1)
953 fatal("%s: ssh_msg_recv failed", __func__);
954 if (buffer_get_char(&m) != 0)
955 fatal("%s: rexec version mismatch", __func__);
956
957 cp = buffer_get_string(&m, &len);
958 if (conf != NULL)
959 buffer_append(conf, cp, len + 1);
960 xfree(cp);
961
962 if (buffer_get_int(&m)) {
963 if (sensitive_data.server_key != NULL)
964 key_free(sensitive_data.server_key);
965 sensitive_data.server_key = key_new_private(KEY_RSA1);
966 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
967 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
968 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
969 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
970 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
971 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
972 rsa_generate_additional_parameters(
973 sensitive_data.server_key->rsa);
974 }
975
976 #ifndef OPENSSL_PRNG_ONLY
977 rexec_recv_rng_seed(&m);
978 #endif
979
980 buffer_free(&m);
981
982 debug3("%s: done", __func__);
983 }
984
985 /* Accept a connection from inetd */
986 static void
987 server_accept_inetd(int *sock_in, int *sock_out)
988 {
989 int fd;
990
991 startup_pipe = -1;
992 if (rexeced_flag) {
993 close(REEXEC_CONFIG_PASS_FD);
994 *sock_in = *sock_out = dup(STDIN_FILENO);
995 if (!debug_flag) {
996 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
997 close(REEXEC_STARTUP_PIPE_FD);
998 }
999 } else {
1000 *sock_in = dup(STDIN_FILENO);
1001 *sock_out = dup(STDOUT_FILENO);
1002 }
1003 /*
1004 * We intentionally do not close the descriptors 0, 1, and 2
1005 * as our code for setting the descriptors won't work if
1006 * ttyfd happens to be one of those.
1007 */
1008 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1009 dup2(fd, STDIN_FILENO);
1010 dup2(fd, STDOUT_FILENO);
1011 if (fd > STDOUT_FILENO)
1012 close(fd);
1013 }
1014 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
1015 }
1016
1017 /*
1018 * Listen for TCP connections
1019 */
1020 static void
1021 server_listen(void)
1022 {
1023 int ret, listen_sock, on = 1;
1024 struct addrinfo *ai;
1025 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1026
1027 for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1028 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1029 continue;
1030 if (num_listen_socks >= MAX_LISTEN_SOCKS)
1031 fatal("Too many listen sockets. "
1032 "Enlarge MAX_LISTEN_SOCKS");
1033 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1034 ntop, sizeof(ntop), strport, sizeof(strport),
1035 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1036 error("getnameinfo failed: %.100s",
1037 ssh_gai_strerror(ret));
1038 continue;
1039 }
1040 /* Create socket for listening. */
1041 listen_sock = socket(ai->ai_family, ai->ai_socktype,
1042 ai->ai_protocol);
1043 if (listen_sock < 0) {
1044 /* kernel may not support ipv6 */
1045 verbose("socket: %.100s", strerror(errno));
1046 continue;
1047 }
1048 if (set_nonblock(listen_sock) == -1) {
1049 close(listen_sock);
1050 continue;
1051 }
1052 /*
1053 * Set socket options.
1054 * Allow local port reuse in TIME_WAIT.
1055 */
1056 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1057 &on, sizeof(on)) == -1)
1058 error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1059
1060 /* Only communicate in IPv6 over AF_INET6 sockets. */
1061 if (ai->ai_family == AF_INET6)
1062 sock_set_v6only(listen_sock);
1063
1064 debug("Bind to port %s on %s.", strport, ntop);
1065
1066 /* Bind the socket to the desired port. */
1067 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1068 error("Bind to port %s on %s failed: %.200s.",
1069 strport, ntop, strerror(errno));
1070 close(listen_sock);
1071 continue;
1072 }
1073 listen_socks[num_listen_socks] = listen_sock;
1074 num_listen_socks++;
1075
1076 /* Start listening on the port. */
1077 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1078 fatal("listen on [%s]:%s: %.100s",
1079 ntop, strport, strerror(errno));
1080 logit("Server listening on %s port %s.", ntop, strport);
1081 }
1082 freeaddrinfo(options.listen_addrs);
1083
1084 if (!num_listen_socks)
1085 fatal("Cannot bind any address.");
1086 }
1087
1088 /*
1089 * The main TCP accept loop. Note that, for the non-debug case, returns
1090 * from this function are in a forked subprocess.
1091 */
1092 static void
1093 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
1094 {
1095 fd_set *fdset;
1096 int i, j, ret, maxfd;
1097 int key_used = 0, startups = 0;
1098 int startup_p[2] = { -1 , -1 };
1099 struct sockaddr_storage from;
1100 socklen_t fromlen;
1101 pid_t pid;
1102
1103 /* setup fd set for accept */
1104 fdset = NULL;
1105 maxfd = 0;
1106 for (i = 0; i < num_listen_socks; i++)
1107 if (listen_socks[i] > maxfd)
1108 maxfd = listen_socks[i];
1109 /* pipes connected to unauthenticated childs */
1110 startup_pipes = xcalloc(options.max_startups, sizeof(int));
1111 for (i = 0; i < options.max_startups; i++)
1112 startup_pipes[i] = -1;
1113
1114 /*
1115 * Stay listening for connections until the system crashes or
1116 * the daemon is killed with a signal.
1117 */
1118 for (;;) {
1119 if (received_sighup)
1120 sighup_restart();
1121 if (fdset != NULL)
1122 xfree(fdset);
1123 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1124 sizeof(fd_mask));
1125
1126 for (i = 0; i < num_listen_socks; i++)
1127 FD_SET(listen_socks[i], fdset);
1128 for (i = 0; i < options.max_startups; i++)
1129 if (startup_pipes[i] != -1)
1130 FD_SET(startup_pipes[i], fdset);
1131
1132 /* Wait in select until there is a connection. */
1133 ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1134 if (ret < 0 && errno != EINTR)
1135 error("select: %.100s", strerror(errno));
1136 if (received_sigterm) {
1137 logit("Received signal %d; terminating.",
1138 (int) received_sigterm);
1139 close_listen_socks();
1140 unlink(options.pid_file);
1141 exit(received_sigterm == SIGTERM ? 0 : 255);
1142 }
1143 if (key_used && key_do_regen) {
1144 generate_ephemeral_server_key();
1145 key_used = 0;
1146 key_do_regen = 0;
1147 }
1148 if (ret < 0)
1149 continue;
1150
1151 for (i = 0; i < options.max_startups; i++)
1152 if (startup_pipes[i] != -1 &&
1153 FD_ISSET(startup_pipes[i], fdset)) {
1154 /*
1155 * the read end of the pipe is ready
1156 * if the child has closed the pipe
1157 * after successful authentication
1158 * or if the child has died
1159 */
1160 close(startup_pipes[i]);
1161 startup_pipes[i] = -1;
1162 startups--;
1163 }
1164 for (i = 0; i < num_listen_socks; i++) {
1165 if (!FD_ISSET(listen_socks[i], fdset))
1166 continue;
1167 fromlen = sizeof(from);
1168 *newsock = accept(listen_socks[i],
1169 (struct sockaddr *)&from, &fromlen);
1170 if (*newsock < 0) {
1171 if (errno != EINTR && errno != EAGAIN &&
1172 errno != EWOULDBLOCK)
1173 error("accept: %.100s", strerror(errno));
1174 continue;
1175 }
1176 if (unset_nonblock(*newsock) == -1) {
1177 close(*newsock);
1178 continue;
1179 }
1180 if (drop_connection(startups) == 1) {
1181 debug("drop connection #%d", startups);
1182 close(*newsock);
1183 continue;
1184 }
1185 if (pipe(startup_p) == -1) {
1186 close(*newsock);
1187 continue;
1188 }
1189
1190 if (rexec_flag && socketpair(AF_UNIX,
1191 SOCK_STREAM, 0, config_s) == -1) {
1192 error("reexec socketpair: %s",
1193 strerror(errno));
1194 close(*newsock);
1195 close(startup_p[0]);
1196 close(startup_p[1]);
1197 continue;
1198 }
1199
1200 for (j = 0; j < options.max_startups; j++)
1201 if (startup_pipes[j] == -1) {
1202 startup_pipes[j] = startup_p[0];
1203 if (maxfd < startup_p[0])
1204 maxfd = startup_p[0];
1205 startups++;
1206 break;
1207 }
1208
1209 /*
1210 * Got connection. Fork a child to handle it, unless
1211 * we are in debugging mode.
1212 */
1213 if (debug_flag) {
1214 /*
1215 * In debugging mode. Close the listening
1216 * socket, and start processing the
1217 * connection without forking.
1218 */
1219 debug("Server will not fork when running in debugging mode.");
1220 close_listen_socks();
1221 *sock_in = *newsock;
1222 *sock_out = *newsock;
1223 close(startup_p[0]);
1224 close(startup_p[1]);
1225 startup_pipe = -1;
1226 pid = getpid();
1227 if (rexec_flag) {
1228 send_rexec_state(config_s[0],
1229 &cfg);
1230 close(config_s[0]);
1231 }
1232 break;
1233 }
1234
1235 /*
1236 * Normal production daemon. Fork, and have
1237 * the child process the connection. The
1238 * parent continues listening.
1239 */
1240 platform_pre_fork();
1241 if ((pid = fork()) == 0) {
1242 /*
1243 * Child. Close the listening and
1244 * max_startup sockets. Start using
1245 * the accepted socket. Reinitialize
1246 * logging (since our pid has changed).
1247 * We break out of the loop to handle
1248 * the connection.
1249 */
1250 platform_post_fork_child();
1251 startup_pipe = startup_p[1];
1252 close_startup_pipes();
1253 close_listen_socks();
1254 *sock_in = *newsock;
1255 *sock_out = *newsock;
1256 log_init(__progname,
1257 options.log_level,
1258 options.log_facility,
1259 log_stderr);
1260 if (rexec_flag)
1261 close(config_s[0]);
1262 break;
1263 }
1264
1265 /* Parent. Stay in the loop. */
1266 platform_post_fork_parent(pid);
1267 if (pid < 0)
1268 error("fork: %.100s", strerror(errno));
1269 else
1270 debug("Forked child %ld.", (long)pid);
1271
1272 close(startup_p[1]);
1273
1274 if (rexec_flag) {
1275 send_rexec_state(config_s[0], &cfg);
1276 close(config_s[0]);
1277 close(config_s[1]);
1278 }
1279
1280 /*
1281 * Mark that the key has been used (it
1282 * was "given" to the child).
1283 */
1284 if ((options.protocol & SSH_PROTO_1) &&
1285 key_used == 0) {
1286 /* Schedule server key regeneration alarm. */
1287 signal(SIGALRM, key_regeneration_alarm);
1288 alarm(options.key_regeneration_time);
1289 key_used = 1;
1290 }
1291
1292 close(*newsock);
1293
1294 /*
1295 * Ensure that our random state differs
1296 * from that of the child
1297 */
1298 arc4random_stir();
1299 }
1300
1301 /* child process check (or debug mode) */
1302 if (num_listen_socks < 0)
1303 break;
1304 }
1305 }
1306
1307
1308 /*
1309 * Main program for the daemon.
1310 */
1311 int
1312 main(int ac, char **av)
1313 {
1314 extern char *optarg;
1315 extern int optind;
1316 int opt, i, j, on = 1;
1317 int sock_in = -1, sock_out = -1, newsock = -1;
1318 const char *remote_ip;
1319 char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1320 int remote_port;
1321 char *line, *p, *cp;
1322 int config_s[2] = { -1 , -1 };
1323 u_int64_t ibytes, obytes;
1324 mode_t new_umask;
1325 Key *key;
1326 Authctxt *authctxt;
1327
1328 #ifdef HAVE_SECUREWARE
1329 (void)set_auth_parameters(ac, av);
1330 #endif
1331 __progname = ssh_get_progname(av[0]);
1332
1333 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1334 saved_argc = ac;
1335 rexec_argc = ac;
1336 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1337 for (i = 0; i < ac; i++)
1338 saved_argv[i] = xstrdup(av[i]);
1339 saved_argv[i] = NULL;
1340
1341 #ifndef HAVE_SETPROCTITLE
1342 /* Prepare for later setproctitle emulation */
1343 compat_init_setproctitle(ac, av);
1344 av = saved_argv;
1345 #endif
1346
1347 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1348 debug("setgroups(): %.200s", strerror(errno));
1349
1350 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1351 sanitise_stdfd();
1352
1353 /* Initialize configuration options to their default values. */
1354 initialize_server_options(&options);
1355
1356 /* Parse command-line arguments. */
1357 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1358 switch (opt) {
1359 case '4':
1360 options.address_family = AF_INET;
1361 break;
1362 case '6':
1363 options.address_family = AF_INET6;
1364 break;
1365 case 'f':
1366 config_file_name = optarg;
1367 break;
1368 case 'c':
1369 if (options.num_host_cert_files >= MAX_HOSTCERTS) {
1370 fprintf(stderr, "too many host certificates.\n");
1371 exit(1);
1372 }
1373 options.host_cert_files[options.num_host_cert_files++] =
1374 derelativise_path(optarg);
1375 break;
1376 case 'd':
1377 if (debug_flag == 0) {
1378 debug_flag = 1;
1379 options.log_level = SYSLOG_LEVEL_DEBUG1;
1380 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1381 options.log_level++;
1382 break;
1383 case 'D':
1384 no_daemon_flag = 1;
1385 break;
1386 case 'e':
1387 log_stderr = 1;
1388 break;
1389 case 'i':
1390 inetd_flag = 1;
1391 break;
1392 case 'r':
1393 rexec_flag = 0;
1394 break;
1395 case 'R':
1396 rexeced_flag = 1;
1397 inetd_flag = 1;
1398 break;
1399 case 'Q':
1400 /* ignored */
1401 break;
1402 case 'q':
1403 options.log_level = SYSLOG_LEVEL_QUIET;
1404 break;
1405 case 'b':
1406 options.server_key_bits = (int)strtonum(optarg, 256,
1407 32768, NULL);
1408 break;
1409 case 'p':
1410 options.ports_from_cmdline = 1;
1411 if (options.num_ports >= MAX_PORTS) {
1412 fprintf(stderr, "too many ports.\n");
1413 exit(1);
1414 }
1415 options.ports[options.num_ports++] = a2port(optarg);
1416 if (options.ports[options.num_ports-1] <= 0) {
1417 fprintf(stderr, "Bad port number.\n");
1418 exit(1);
1419 }
1420 break;
1421 case 'g':
1422 if ((options.login_grace_time = convtime(optarg)) == -1) {
1423 fprintf(stderr, "Invalid login grace time.\n");
1424 exit(1);
1425 }
1426 break;
1427 case 'k':
1428 if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1429 fprintf(stderr, "Invalid key regeneration interval.\n");
1430 exit(1);
1431 }
1432 break;
1433 case 'h':
1434 if (options.num_host_key_files >= MAX_HOSTKEYS) {
1435 fprintf(stderr, "too many host keys.\n");
1436 exit(1);
1437 }
1438 options.host_key_files[options.num_host_key_files++] =
1439 derelativise_path(optarg);
1440 break;
1441 case 't':
1442 test_flag = 1;
1443 break;
1444 case 'T':
1445 test_flag = 2;
1446 break;
1447 case 'C':
1448 cp = optarg;
1449 while ((p = strsep(&cp, ",")) && *p != '\0') {
1450 if (strncmp(p, "addr=", 5) == 0)
1451 test_addr = xstrdup(p + 5);
1452 else if (strncmp(p, "host=", 5) == 0)
1453 test_host = xstrdup(p + 5);
1454 else if (strncmp(p, "user=", 5) == 0)
1455 test_user = xstrdup(p + 5);
1456 else {
1457 fprintf(stderr, "Invalid test "
1458 "mode specification %s\n", p);
1459 exit(1);
1460 }
1461 }
1462 break;
1463 case 'u':
1464 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1465 if (utmp_len > MAXHOSTNAMELEN) {
1466 fprintf(stderr, "Invalid utmp length.\n");
1467 exit(1);
1468 }
1469 break;
1470 case 'o':
1471 line = xstrdup(optarg);
1472 if (process_server_config_line(&options, line,
1473 "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1474 exit(1);
1475 xfree(line);
1476 break;
1477 case '?':
1478 default:
1479 usage();
1480 break;
1481 }
1482 }
1483 if (rexeced_flag || inetd_flag)
1484 rexec_flag = 0;
1485 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1486 fatal("sshd re-exec requires execution with an absolute path");
1487 if (rexeced_flag)
1488 closefrom(REEXEC_MIN_FREE_FD);
1489 else
1490 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1491
1492 OpenSSL_add_all_algorithms();
1493
1494 /*
1495 * Force logging to stderr until we have loaded the private host
1496 * key (unless started from inetd)
1497 */
1498 log_init(__progname,
1499 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1500 SYSLOG_LEVEL_INFO : options.log_level,
1501 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1502 SYSLOG_FACILITY_AUTH : options.log_facility,
1503 log_stderr || !inetd_flag);
1504
1505 /*
1506 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1507 * root's environment
1508 */
1509 if (getenv("KRB5CCNAME") != NULL)
1510 unsetenv("KRB5CCNAME");
1511
1512 #ifdef _UNICOS
1513 /* Cray can define user privs drop all privs now!
1514 * Not needed on PRIV_SU systems!
1515 */
1516 drop_cray_privs();
1517 #endif
1518
1519 sensitive_data.server_key = NULL;
1520 sensitive_data.ssh1_host_key = NULL;
1521 sensitive_data.have_ssh1_key = 0;
1522 sensitive_data.have_ssh2_key = 0;
1523
1524 /*
1525 * If we're doing an extended config test, make sure we have all of
1526 * the parameters we need. If we're not doing an extended test,
1527 * do not silently ignore connection test params.
1528 */
1529 if (test_flag >= 2 &&
1530 (test_user != NULL || test_host != NULL || test_addr != NULL)
1531 && (test_user == NULL || test_host == NULL || test_addr == NULL))
1532 fatal("user, host and addr are all required when testing "
1533 "Match configs");
1534 if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1535 test_addr != NULL))
1536 fatal("Config test connection parameter (-C) provided without "
1537 "test mode (-T)");
1538
1539 /* Fetch our configuration */
1540 buffer_init(&cfg);
1541 if (rexeced_flag)
1542 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1543 else
1544 load_server_config(config_file_name, &cfg);
1545
1546 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1547 &cfg, NULL, NULL, NULL);
1548
1549 seed_rng();
1550
1551 /* Fill in default values for those options not explicitly set. */
1552 fill_default_server_options(&options);
1553
1554 /* challenge-response is implemented via keyboard interactive */
1555 if (options.challenge_response_authentication)
1556 options.kbd_interactive_authentication = 1;
1557
1558 /* set default channel AF */
1559 channel_set_af(options.address_family);
1560
1561 /* Check that there are no remaining arguments. */
1562 if (optind < ac) {
1563 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1564 exit(1);
1565 }
1566
1567 debug("sshd version %.100s", SSH_RELEASE);
1568
1569 /* Store privilege separation user for later use if required. */
1570 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1571 if (use_privsep || options.kerberos_authentication)
1572 fatal("Privilege separation user %s does not exist",
1573 SSH_PRIVSEP_USER);
1574 } else {
1575 if (privsep_pw->pw_passwd)
1576 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd));
1577 privsep_pw = pwcopy(privsep_pw);
1578 if (privsep_pw->pw_passwd)
1579 xfree(privsep_pw->pw_passwd);
1580 privsep_pw->pw_passwd = xstrdup("*");
1581 }
1582 endpwent();
1583
1584 /* load private host keys */
1585 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1586 sizeof(Key *));
1587 for (i = 0; i < options.num_host_key_files; i++)
1588 sensitive_data.host_keys[i] = NULL;
1589
1590 for (i = 0; i < options.num_host_key_files; i++) {
1591 key = key_load_private(options.host_key_files[i], "", NULL);
1592 sensitive_data.host_keys[i] = key;
1593 if (key == NULL) {
1594 error("Could not load host key: %s",
1595 options.host_key_files[i]);
1596 sensitive_data.host_keys[i] = NULL;
1597 continue;
1598 }
1599 switch (key->type) {
1600 case KEY_RSA1:
1601 sensitive_data.ssh1_host_key = key;
1602 sensitive_data.have_ssh1_key = 1;
1603 break;
1604 case KEY_RSA:
1605 case KEY_DSA:
1606 case KEY_ECDSA:
1607 sensitive_data.have_ssh2_key = 1;
1608 break;
1609 }
1610 debug("private host key: #%d type %d %s", i, key->type,
1611 key_type(key));
1612 }
1613 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1614 logit("Disabling protocol version 1. Could not load host key");
1615 options.protocol &= ~SSH_PROTO_1;
1616 }
1617 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1618 logit("Disabling protocol version 2. Could not load host key");
1619 options.protocol &= ~SSH_PROTO_2;
1620 }
1621 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1622 logit("sshd: no hostkeys available -- exiting.");
1623 exit(1);
1624 }
1625
1626 /*
1627 * Load certificates. They are stored in an array at identical
1628 * indices to the public keys that they relate to.
1629 */
1630 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1631 sizeof(Key *));
1632 for (i = 0; i < options.num_host_key_files; i++)
1633 sensitive_data.host_certificates[i] = NULL;
1634
1635 for (i = 0; i < options.num_host_cert_files; i++) {
1636 key = key_load_public(options.host_cert_files[i], NULL);
1637 if (key == NULL) {
1638 error("Could not load host certificate: %s",
1639 options.host_cert_files[i]);
1640 continue;
1641 }
1642 if (!key_is_cert(key)) {
1643 error("Certificate file is not a certificate: %s",
1644 options.host_cert_files[i]);
1645 key_free(key);
1646 continue;
1647 }
1648 /* Find matching private key */
1649 for (j = 0; j < options.num_host_key_files; j++) {
1650 if (key_equal_public(key,
1651 sensitive_data.host_keys[j])) {
1652 sensitive_data.host_certificates[j] = key;
1653 break;
1654 }
1655 }
1656 if (j >= options.num_host_key_files) {
1657 error("No matching private key for certificate: %s",
1658 options.host_cert_files[i]);
1659 key_free(key);
1660 continue;
1661 }
1662 sensitive_data.host_certificates[j] = key;
1663 debug("host certificate: #%d type %d %s", j, key->type,
1664 key_type(key));
1665 }
1666 /* Check certain values for sanity. */
1667 if (options.protocol & SSH_PROTO_1) {
1668 if (options.server_key_bits < 512 ||
1669 options.server_key_bits > 32768) {
1670 fprintf(stderr, "Bad server key size.\n");
1671 exit(1);
1672 }
1673 /*
1674 * Check that server and host key lengths differ sufficiently. This
1675 * is necessary to make double encryption work with rsaref. Oh, I
1676 * hate software patents. I dont know if this can go? Niels
1677 */
1678 if (options.server_key_bits >
1679 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1680 SSH_KEY_BITS_RESERVED && options.server_key_bits <
1681 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1682 SSH_KEY_BITS_RESERVED) {
1683 options.server_key_bits =
1684 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1685 SSH_KEY_BITS_RESERVED;
1686 debug("Forcing server key to %d bits to make it differ from host key.",
1687 options.server_key_bits);
1688 }
1689 }
1690
1691 if (use_privsep) {
1692 struct stat st;
1693
1694 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1695 (S_ISDIR(st.st_mode) == 0))
1696 fatal("Missing privilege separation directory: %s",
1697 _PATH_PRIVSEP_CHROOT_DIR);
1698
1699 #ifdef HAVE_CYGWIN
1700 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1701 (st.st_uid != getuid () ||
1702 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1703 #else
1704 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1705 #endif
1706 fatal("%s must be owned by root and not group or "
1707 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1708 }
1709
1710 if (test_flag > 1) {
1711 if (test_user != NULL && test_addr != NULL && test_host != NULL)
1712 parse_server_match_config(&options, test_user,
1713 test_host, test_addr);
1714 dump_config(&options);
1715 }
1716
1717 /* Configuration looks good, so exit if in test mode. */
1718 if (test_flag)
1719 exit(0);
1720
1721 /*
1722 * Clear out any supplemental groups we may have inherited. This
1723 * prevents inadvertent creation of files with bad modes (in the
1724 * portable version at least, it's certainly possible for PAM
1725 * to create a file, and we can't control the code in every
1726 * module which might be used).
1727 */
1728 if (setgroups(0, NULL) < 0)
1729 debug("setgroups() failed: %.200s", strerror(errno));
1730
1731 if (rexec_flag) {
1732 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1733 for (i = 0; i < rexec_argc; i++) {
1734 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1735 rexec_argv[i] = saved_argv[i];
1736 }
1737 rexec_argv[rexec_argc] = "-R";
1738 rexec_argv[rexec_argc + 1] = NULL;
1739 }
1740
1741 /* Ensure that umask disallows at least group and world write */
1742 new_umask = umask(0077) | 0022;
1743 (void) umask(new_umask);
1744
1745 /* Initialize the log (it is reinitialized below in case we forked). */
1746 if (debug_flag && (!inetd_flag || rexeced_flag))
1747 log_stderr = 1;
1748 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1749
1750 /*
1751 * If not in debugging mode, and not started from inetd, disconnect
1752 * from the controlling terminal, and fork. The original process
1753 * exits.
1754 */
1755 if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1756 #ifdef TIOCNOTTY
1757 int fd;
1758 #endif /* TIOCNOTTY */
1759 if (daemon(0, 0) < 0)
1760 fatal("daemon() failed: %.200s", strerror(errno));
1761
1762 /* Disconnect from the controlling tty. */
1763 #ifdef TIOCNOTTY
1764 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1765 if (fd >= 0) {
1766 (void) ioctl(fd, TIOCNOTTY, NULL);
1767 close(fd);
1768 }
1769 #endif /* TIOCNOTTY */
1770 }
1771 /* Reinitialize the log (because of the fork above). */
1772 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1773
1774 /* Initialize the random number generator. */
1775 arc4random_stir();
1776
1777 /* Chdir to the root directory so that the current disk can be
1778 unmounted if desired. */
1779 chdir("/");
1780
1781 /* ignore SIGPIPE */
1782 signal(SIGPIPE, SIG_IGN);
1783
1784 /* Get a connection, either from inetd or a listening TCP socket */
1785 if (inetd_flag) {
1786 server_accept_inetd(&sock_in, &sock_out);
1787 } else {
1788 platform_pre_listen();
1789 server_listen();
1790
1791 if (options.protocol & SSH_PROTO_1)
1792 generate_ephemeral_server_key();
1793
1794 signal(SIGHUP, sighup_handler);
1795 signal(SIGCHLD, main_sigchld_handler);
1796 signal(SIGTERM, sigterm_handler);
1797 signal(SIGQUIT, sigterm_handler);
1798
1799 /*
1800 * Write out the pid file after the sigterm handler
1801 * is setup and the listen sockets are bound
1802 */
1803 if (!debug_flag) {
1804 FILE *f = fopen(options.pid_file, "w");
1805
1806 if (f == NULL) {
1807 error("Couldn't create pid file \"%s\": %s",
1808 options.pid_file, strerror(errno));
1809 } else {
1810 fprintf(f, "%ld\n", (long) getpid());
1811 fclose(f);
1812 }
1813 }
1814
1815 /* Accept a connection and return in a forked child */
1816 server_accept_loop(&sock_in, &sock_out,
1817 &newsock, config_s);
1818 }
1819
1820 /* This is the child processing a new connection. */
1821 setproctitle("%s", "[accepted]");
1822
1823 /*
1824 * Create a new session and process group since the 4.4BSD
1825 * setlogin() affects the entire process group. We don't
1826 * want the child to be able to affect the parent.
1827 */
1828 #if !defined(SSHD_ACQUIRES_CTTY)
1829 /*
1830 * If setsid is called, on some platforms sshd will later acquire a
1831 * controlling terminal which will result in "could not set
1832 * controlling tty" errors.
1833 */
1834 if (!debug_flag && !inetd_flag && setsid() < 0)
1835 error("setsid: %.100s", strerror(errno));
1836 #endif
1837
1838 if (rexec_flag) {
1839 int fd;
1840
1841 debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1842 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1843 dup2(newsock, STDIN_FILENO);
1844 dup2(STDIN_FILENO, STDOUT_FILENO);
1845 if (startup_pipe == -1)
1846 close(REEXEC_STARTUP_PIPE_FD);
1847 else
1848 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1849
1850 dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1851 close(config_s[1]);
1852 if (startup_pipe != -1)
1853 close(startup_pipe);
1854
1855 execv(rexec_argv[0], rexec_argv);
1856
1857 /* Reexec has failed, fall back and continue */
1858 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1859 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1860 log_init(__progname, options.log_level,
1861 options.log_facility, log_stderr);
1862
1863 /* Clean up fds */
1864 startup_pipe = REEXEC_STARTUP_PIPE_FD;
1865 close(config_s[1]);
1866 close(REEXEC_CONFIG_PASS_FD);
1867 newsock = sock_out = sock_in = dup(STDIN_FILENO);
1868 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1869 dup2(fd, STDIN_FILENO);
1870 dup2(fd, STDOUT_FILENO);
1871 if (fd > STDERR_FILENO)
1872 close(fd);
1873 }
1874 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1875 sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1876 }
1877
1878 /* Executed child processes don't need these. */
1879 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1880 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1881
1882 /*
1883 * Disable the key regeneration alarm. We will not regenerate the
1884 * key since we are no longer in a position to give it to anyone. We
1885 * will not restart on SIGHUP since it no longer makes sense.
1886 */
1887 alarm(0);
1888 signal(SIGALRM, SIG_DFL);
1889 signal(SIGHUP, SIG_DFL);
1890 signal(SIGTERM, SIG_DFL);
1891 signal(SIGQUIT, SIG_DFL);
1892 signal(SIGCHLD, SIG_DFL);
1893 signal(SIGINT, SIG_DFL);
1894
1895 /*
1896 * Register our connection. This turns encryption off because we do
1897 * not have a key.
1898 */
1899 packet_set_connection(sock_in, sock_out);
1900 packet_set_server();
1901
1902 /* Set SO_KEEPALIVE if requested. */
1903 if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1904 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1905 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1906
1907 if ((remote_port = get_remote_port()) < 0) {
1908 debug("get_remote_port failed");
1909 cleanup_exit(255);
1910 }
1911
1912 /*
1913 * We use get_canonical_hostname with usedns = 0 instead of
1914 * get_remote_ipaddr here so IP options will be checked.
1915 */
1916 (void) get_canonical_hostname(0);
1917 /*
1918 * The rest of the code depends on the fact that
1919 * get_remote_ipaddr() caches the remote ip, even if
1920 * the socket goes away.
1921 */
1922 remote_ip = get_remote_ipaddr();
1923
1924 #ifdef SSH_AUDIT_EVENTS
1925 audit_connection_from(remote_ip, remote_port);
1926 #endif
1927 #ifdef LIBWRAP
1928 allow_severity = options.log_facility|LOG_INFO;
1929 deny_severity = options.log_facility|LOG_WARNING;
1930 /* Check whether logins are denied from this host. */
1931 if (packet_connection_is_on_socket()) {
1932 struct request_info req;
1933
1934 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1935 fromhost(&req);
1936
1937 if (!hosts_access(&req)) {
1938 debug("Connection refused by tcp wrapper");
1939 refuse(&req);
1940 /* NOTREACHED */
1941 fatal("libwrap refuse returns");
1942 }
1943 }
1944 #endif /* LIBWRAP */
1945
1946 /* Log the connection. */
1947 verbose("Connection from %.500s port %d", remote_ip, remote_port);
1948
1949 /*
1950 * We don't want to listen forever unless the other side
1951 * successfully authenticates itself. So we set up an alarm which is
1952 * cleared after successful authentication. A limit of zero
1953 * indicates no limit. Note that we don't set the alarm in debugging
1954 * mode; it is just annoying to have the server exit just when you
1955 * are about to discover the bug.
1956 */
1957 signal(SIGALRM, grace_alarm_handler);
1958 if (!debug_flag)
1959 alarm(options.login_grace_time);
1960
1961 sshd_exchange_identification(sock_in, sock_out);
1962
1963 /* In inetd mode, generate ephemeral key only for proto 1 connections */
1964 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1965 generate_ephemeral_server_key();
1966
1967 packet_set_nonblocking();
1968
1969 /* allocate authentication context */
1970 authctxt = xcalloc(1, sizeof(*authctxt));
1971
1972 authctxt->loginmsg = &loginmsg;
1973
1974 /* XXX global for cleanup, access from other modules */
1975 the_authctxt = authctxt;
1976
1977 /* prepare buffer to collect messages to display to user after login */
1978 buffer_init(&loginmsg);
1979 auth_debug_reset();
1980
1981 if (use_privsep)
1982 if (privsep_preauth(authctxt) == 1)
1983 goto authenticated;
1984
1985 /* perform the key exchange */
1986 /* authenticate user and start session */
1987 if (compat20) {
1988 do_ssh2_kex();
1989 do_authentication2(authctxt);
1990 } else {
1991 do_ssh1_kex();
1992 do_authentication(authctxt);
1993 }
1994 /*
1995 * If we use privilege separation, the unprivileged child transfers
1996 * the current keystate and exits
1997 */
1998 if (use_privsep) {
1999 mm_send_keystate(pmonitor);
2000 exit(0);
2001 }
2002
2003 authenticated:
2004 /*
2005 * Cancel the alarm we set to limit the time taken for
2006 * authentication.
2007 */
2008 alarm(0);
2009 signal(SIGALRM, SIG_DFL);
2010 authctxt->authenticated = 1;
2011 if (startup_pipe != -1) {
2012 close(startup_pipe);
2013 startup_pipe = -1;
2014 }
2015
2016 #ifdef SSH_AUDIT_EVENTS
2017 audit_event(SSH_AUTH_SUCCESS);
2018 #endif
2019
2020 #ifdef GSSAPI
2021 if (options.gss_authentication) {
2022 temporarily_use_uid(authctxt->pw);
2023 ssh_gssapi_storecreds();
2024 restore_uid();
2025 }
2026 #endif
2027 #ifdef USE_PAM
2028 if (options.use_pam) {
2029 do_pam_setcred(1);
2030 do_pam_session();
2031 }
2032 #endif
2033
2034 /*
2035 * In privilege separation, we fork another child and prepare
2036 * file descriptor passing.
2037 */
2038 if (use_privsep) {
2039 privsep_postauth(authctxt);
2040 /* the monitor process [priv] will not return */
2041 if (!compat20)
2042 destroy_sensitive_data();
2043 }
2044
2045 packet_set_timeout(options.client_alive_interval,
2046 options.client_alive_count_max);
2047
2048 /* Start session. */
2049 do_authenticated(authctxt);
2050
2051 /* The connection has been terminated. */
2052 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
2053 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
2054 verbose("Transferred: sent %llu, received %llu bytes",
2055 (unsigned long long)obytes, (unsigned long long)ibytes);
2056
2057 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
2058
2059 #ifdef USE_PAM
2060 if (options.use_pam)
2061 finish_pam();
2062 #endif /* USE_PAM */
2063
2064 #ifdef SSH_AUDIT_EVENTS
2065 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE));
2066 #endif
2067
2068 packet_close();
2069
2070 if (use_privsep)
2071 mm_terminate();
2072
2073 exit(0);
2074 }
2075
2076 /*
2077 * Decrypt session_key_int using our private server key and private host key
2078 * (key with larger modulus first).
2079 */
2080 int
2081 ssh1_session_key(BIGNUM *session_key_int)
2082 {
2083 int rsafail = 0;
2084
2085 if (BN_cmp(sensitive_data.server_key->rsa->n,
2086 sensitive_data.ssh1_host_key->rsa->n) > 0) {
2087 /* Server key has bigger modulus. */
2088 if (BN_num_bits(sensitive_data.server_key->rsa->n) <
2089 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
2090 SSH_KEY_BITS_RESERVED) {
2091 fatal("do_connection: %s: "
2092 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
2093 get_remote_ipaddr(),
2094 BN_num_bits(sensitive_data.server_key->rsa->n),
2095 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2096 SSH_KEY_BITS_RESERVED);
2097 }
2098 if (rsa_private_decrypt(session_key_int, session_key_int,
2099 sensitive_data.server_key->rsa) <= 0)
2100 rsafail++;
2101 if (rsa_private_decrypt(session_key_int, session_key_int,
2102 sensitive_data.ssh1_host_key->rsa) <= 0)
2103 rsafail++;
2104 } else {
2105 /* Host key has bigger modulus (or they are equal). */
2106 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
2107 BN_num_bits(sensitive_data.server_key->rsa->n) +
2108 SSH_KEY_BITS_RESERVED) {
2109 fatal("do_connection: %s: "
2110 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
2111 get_remote_ipaddr(),
2112 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
2113 BN_num_bits(sensitive_data.server_key->rsa->n),
2114 SSH_KEY_BITS_RESERVED);
2115 }
2116 if (rsa_private_decrypt(session_key_int, session_key_int,
2117 sensitive_data.ssh1_host_key->rsa) < 0)
2118 rsafail++;
2119 if (rsa_private_decrypt(session_key_int, session_key_int,
2120 sensitive_data.server_key->rsa) < 0)
2121 rsafail++;
2122 }
2123 return (rsafail);
2124 }
2125 /*
2126 * SSH1 key exchange
2127 */
2128 static void
2129 do_ssh1_kex(void)
2130 {
2131 int i, len;
2132 int rsafail = 0;
2133 BIGNUM *session_key_int;
2134 u_char session_key[SSH_SESSION_KEY_LENGTH];
2135 u_char cookie[8];
2136 u_int cipher_type, auth_mask, protocol_flags;
2137
2138 /*
2139 * Generate check bytes that the client must send back in the user
2140 * packet in order for it to be accepted; this is used to defy ip
2141 * spoofing attacks. Note that this only works against somebody
2142 * doing IP spoofing from a remote machine; any machine on the local
2143 * network can still see outgoing packets and catch the random
2144 * cookie. This only affects rhosts authentication, and this is one
2145 * of the reasons why it is inherently insecure.
2146 */
2147 arc4random_buf(cookie, sizeof(cookie));
2148
2149 /*
2150 * Send our public key. We include in the packet 64 bits of random
2151 * data that must be matched in the reply in order to prevent IP
2152 * spoofing.
2153 */
2154 packet_start(SSH_SMSG_PUBLIC_KEY);
2155 for (i = 0; i < 8; i++)
2156 packet_put_char(cookie[i]);
2157
2158 /* Store our public server RSA key. */
2159 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
2160 packet_put_bignum(sensitive_data.server_key->rsa->e);
2161 packet_put_bignum(sensitive_data.server_key->rsa->n);
2162
2163 /* Store our public host RSA key. */
2164 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2165 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
2166 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
2167
2168 /* Put protocol flags. */
2169 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
2170
2171 /* Declare which ciphers we support. */
2172 packet_put_int(cipher_mask_ssh1(0));
2173
2174 /* Declare supported authentication types. */
2175 auth_mask = 0;
2176 if (options.rhosts_rsa_authentication)
2177 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
2178 if (options.rsa_authentication)
2179 auth_mask |= 1 << SSH_AUTH_RSA;
2180 if (options.challenge_response_authentication == 1)
2181 auth_mask |= 1 << SSH_AUTH_TIS;
2182 if (options.password_authentication)
2183 auth_mask |= 1 << SSH_AUTH_PASSWORD;
2184 packet_put_int(auth_mask);
2185
2186 /* Send the packet and wait for it to be sent. */
2187 packet_send();
2188 packet_write_wait();
2189
2190 debug("Sent %d bit server key and %d bit host key.",
2191 BN_num_bits(sensitive_data.server_key->rsa->n),
2192 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
2193
2194 /* Read clients reply (cipher type and session key). */
2195 packet_read_expect(SSH_CMSG_SESSION_KEY);
2196
2197 /* Get cipher type and check whether we accept this. */
2198 cipher_type = packet_get_char();
2199
2200 if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
2201 packet_disconnect("Warning: client selects unsupported cipher.");
2202
2203 /* Get check bytes from the packet. These must match those we
2204 sent earlier with the public key packet. */
2205 for (i = 0; i < 8; i++)
2206 if (cookie[i] != packet_get_char())
2207 packet_disconnect("IP Spoofing check bytes do not match.");
2208
2209 debug("Encryption type: %.200s", cipher_name(cipher_type));
2210
2211 /* Get the encrypted integer. */
2212 if ((session_key_int = BN_new()) == NULL)
2213 fatal("do_ssh1_kex: BN_new failed");
2214 packet_get_bignum(session_key_int);
2215
2216 protocol_flags = packet_get_int();
2217 packet_set_protocol_flags(protocol_flags);
2218 packet_check_eom();
2219
2220 /* Decrypt session_key_int using host/server keys */
2221 rsafail = PRIVSEP(ssh1_session_key(session_key_int));
2222
2223 /*
2224 * Extract session key from the decrypted integer. The key is in the
2225 * least significant 256 bits of the integer; the first byte of the
2226 * key is in the highest bits.
2227 */
2228 if (!rsafail) {
2229 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
2230 len = BN_num_bytes(session_key_int);
2231 if (len < 0 || (u_int)len > sizeof(session_key)) {
2232 error("do_ssh1_kex: bad session key len from %s: "
2233 "session_key_int %d > sizeof(session_key) %lu",
2234 get_remote_ipaddr(), len, (u_long)sizeof(session_key));
2235 rsafail++;
2236 } else {
2237 memset(session_key, 0, sizeof(session_key));
2238 BN_bn2bin(session_key_int,
2239 session_key + sizeof(session_key) - len);
2240
2241 derive_ssh1_session_id(
2242 sensitive_data.ssh1_host_key->rsa->n,
2243 sensitive_data.server_key->rsa->n,
2244 cookie, session_id);
2245 /*
2246 * Xor the first 16 bytes of the session key with the
2247 * session id.
2248 */
2249 for (i = 0; i < 16; i++)
2250 session_key[i] ^= session_id[i];
2251 }
2252 }
2253 if (rsafail) {
2254 int bytes = BN_num_bytes(session_key_int);
2255 u_char *buf = xmalloc(bytes);
2256 MD5_CTX md;
2257
2258 logit("do_connection: generating a fake encryption key");
2259 BN_bn2bin(session_key_int, buf);
2260 MD5_Init(&md);
2261 MD5_Update(&md, buf, bytes);
2262 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2263 MD5_Final(session_key, &md);
2264 MD5_Init(&md);
2265 MD5_Update(&md, session_key, 16);
2266 MD5_Update(&md, buf, bytes);
2267 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
2268 MD5_Final(session_key + 16, &md);
2269 memset(buf, 0, bytes);
2270 xfree(buf);
2271 for (i = 0; i < 16; i++)
2272 session_id[i] = session_key[i] ^ session_key[i + 16];
2273 }
2274 /* Destroy the private and public keys. No longer. */
2275 destroy_sensitive_data();
2276
2277 if (use_privsep)
2278 mm_ssh1_session_id(session_id);
2279
2280 /* Destroy the decrypted integer. It is no longer needed. */
2281 BN_clear_free(session_key_int);
2282
2283 /* Set the session key. From this on all communications will be encrypted. */
2284 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2285
2286 /* Destroy our copy of the session key. It is no longer needed. */
2287 memset(session_key, 0, sizeof(session_key));
2288
2289 debug("Received session key; encryption turned on.");
2290
2291 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
2292 packet_start(SSH_SMSG_SUCCESS);
2293 packet_send();
2294 packet_write_wait();
2295 }
2296
2297 /*
2298 * SSH2 key exchange: diffie-hellman-group1-sha1
2299 */
2300 static void
2301 do_ssh2_kex(void)
2302 {
2303 Kex *kex;
2304
2305 if (options.ciphers != NULL) {
2306 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2307 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
2308 }
2309 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2310 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2311 myproposal[PROPOSAL_ENC_ALGS_STOC] =
2312 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2313
2314 if (options.macs != NULL) {
2315 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2316 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
2317 }
2318 if (options.compression == COMP_NONE) {
2319 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2320 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
2321 } else if (options.compression == COMP_DELAYED) {
2322 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2323 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
2324 }
2325 if (options.kex_algorithms != NULL)
2326 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
2327
2328 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2329
2330 /* start key exchange */
2331 kex = kex_setup(myproposal);
2332 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
2333 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
2334 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
2335 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
2336 kex->kex[KEX_ECDH_SHA2] = kexecdh_server;
2337 kex->server = 1;
2338 kex->client_version_string=client_version_string;
2339 kex->server_version_string=server_version_string;
2340 kex->load_host_public_key=&get_hostkey_public_by_type;
2341 kex->load_host_private_key=&get_hostkey_private_by_type;
2342 kex->host_key_index=&get_hostkey_index;
2343
2344 xxx_kex = kex;
2345
2346 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
2347
2348 session_id2 = kex->session_id;
2349 session_id2_len = kex->session_id_len;
2350
2351 #ifdef DEBUG_KEXDH
2352 /* send 1st encrypted/maced/compressed message */
2353 packet_start(SSH2_MSG_IGNORE);
2354 packet_put_cstring("markus");
2355 packet_send();
2356 packet_write_wait();
2357 #endif
2358 debug("KEX done");
2359 }
2360
2361 /* server specific fatal cleanup */
2362 void
2363 cleanup_exit(int i)
2364 {
2365 if (the_authctxt)
2366 do_cleanup(the_authctxt);
2367 #ifdef SSH_AUDIT_EVENTS
2368 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
2369 if (!use_privsep || mm_is_monitor())
2370 audit_event(SSH_CONNECTION_ABANDON);
2371 #endif
2372 _exit(i);
2373 }
2374