1 /* $OpenBSD: sshd-session.c,v 1.4 2024/06/26 23:16:52 deraadt Exp $ */
2 /*
3 * SSH2 implementation:
4 * Privilege Separation:
5 *
6 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
7 * Copyright (c) 2002 Niels Provos. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30 #include "includes.h"
31
32 #include <sys/types.h>
33 #include <sys/ioctl.h>
34 #include <sys/socket.h>
35 #ifdef HAVE_SYS_STAT_H
36 # include <sys/stat.h>
37 #endif
38 #ifdef HAVE_SYS_TIME_H
39 # include <sys/time.h>
40 #endif
41 #include "openbsd-compat/sys-tree.h"
42 #include "openbsd-compat/sys-queue.h"
43 #include <sys/wait.h>
44
45 #include <errno.h>
46 #include <fcntl.h>
47 #include <netdb.h>
48 #ifdef HAVE_PATHS_H
49 # include <paths.h>
50 #endif
51 #include <pwd.h>
52 #include <grp.h>
53 #include <signal.h>
54 #include <stdio.h>
55 #include <stdlib.h>
56 #include <string.h>
57 #include <stdarg.h>
58 #include <unistd.h>
59 #include <limits.h>
60
61 #ifdef WITH_OPENSSL
62 #include <openssl/bn.h>
63 #include <openssl/evp.h>
64 #include <openssl/rand.h>
65 #include "openbsd-compat/openssl-compat.h"
66 #endif
67
68 #ifdef HAVE_SECUREWARE
69 #include <sys/security.h>
70 #include <prot.h>
71 #endif
72
73 #include "xmalloc.h"
74 #include "ssh.h"
75 #include "ssh2.h"
76 #include "sshpty.h"
77 #include "packet.h"
78 #include "log.h"
79 #include "sshbuf.h"
80 #include "misc.h"
81 #include "match.h"
82 #include "servconf.h"
83 #include "uidswap.h"
84 #include "compat.h"
85 #include "cipher.h"
86 #include "digest.h"
87 #include "sshkey.h"
88 #include "kex.h"
89 #include "authfile.h"
90 #include "pathnames.h"
91 #include "atomicio.h"
92 #include "canohost.h"
93 #include "hostfile.h"
94 #include "auth.h"
95 #include "authfd.h"
96 #include "msg.h"
97 #include "dispatch.h"
98 #include "channels.h"
99 #include "session.h"
100 #include "monitor.h"
101 #ifdef GSSAPI
102 #include "ssh-gss.h"
103 #endif
104 #include "monitor_wrap.h"
105 #include "ssh-sandbox.h"
106 #include "auth-options.h"
107 #include "version.h"
108 #include "ssherr.h"
109 #include "sk-api.h"
110 #include "srclimit.h"
111 #include "dh.h"
112
113 /* Re-exec fds */
114 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
115 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
116 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
117 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
118
119 extern char *__progname;
120
121 /* Server configuration options. */
122 ServerOptions options;
123
124 /* Name of the server configuration file. */
125 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
126
127 /*
128 * Debug mode flag. This can be set on the command line. If debug
129 * mode is enabled, extra debugging output will be sent to the system
130 * log, the daemon will not go to background, and will exit after processing
131 * the first connection.
132 */
133 int debug_flag = 0;
134
135 /* Flag indicating that the daemon is being started from inetd. */
136 static int inetd_flag = 0;
137
138 /* debug goes to stderr unless inetd_flag is set */
139 static int log_stderr = 0;
140
141 /* Saved arguments to main(). */
142 static char **saved_argv;
143 static int saved_argc;
144
145 /* Daemon's agent connection */
146 int auth_sock = -1;
147 static int have_agent = 0;
148
149 /*
150 * Any really sensitive data in the application is contained in this
151 * structure. The idea is that this structure could be locked into memory so
152 * that the pages do not get written into swap. However, there are some
153 * problems. The private key contains BIGNUMs, and we do not (in principle)
154 * have access to the internals of them, and locking just the structure is
155 * not very useful. Currently, memory locking is not implemented.
156 */
157 struct {
158 u_int num_hostkeys;
159 struct sshkey **host_keys; /* all private host keys */
160 struct sshkey **host_pubkeys; /* all public host keys */
161 struct sshkey **host_certificates; /* all public host certificates */
162 } sensitive_data;
163
164 /* record remote hostname or ip */
165 u_int utmp_len = HOST_NAME_MAX+1;
166
167 static int startup_pipe = -1; /* in child */
168
169 /* variables used for privilege separation */
170 struct monitor *pmonitor = NULL;
171 int privsep_is_preauth = 1;
172 static int privsep_chroot = 1;
173
174 /* Unprivileged user */
175 struct passwd *privsep_pw = NULL;
176
177 /* global connection state and authentication contexts */
178 Authctxt *the_authctxt = NULL;
179 struct ssh *the_active_state;
180
181 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
182 struct sshauthopt *auth_opts = NULL;
183
184 /* sshd_config buffer */
185 struct sshbuf *cfg;
186
187 /* Included files from the configuration file */
188 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
189
190 /* message to be displayed after login */
191 struct sshbuf *loginmsg;
192
193 /* Prototypes for various functions defined later in this file. */
194 void destroy_sensitive_data(void);
195 void demote_sensitive_data(void);
196 static void do_ssh2_kex(struct ssh *);
197
198 /*
199 * Signal handler for the alarm after the login grace period has expired.
200 * As usual, this may only take signal-safe actions, even though it is
201 * terminal.
202 */
203 static void
grace_alarm_handler(int sig)204 grace_alarm_handler(int sig)
205 {
206 /*
207 * Try to kill any processes that we have spawned, E.g. authorized
208 * keys command helpers or privsep children.
209 */
210 if (getpgid(0) == getpid()) {
211 struct sigaction sa;
212
213 /* mask all other signals while in handler */
214 memset(&sa, 0, sizeof(sa));
215 sa.sa_handler = SIG_IGN;
216 sigfillset(&sa.sa_mask);
217 sa.sa_flags = SA_RESTART;
218 (void)sigaction(SIGTERM, &sa, NULL);
219 kill(0, SIGTERM);
220 }
221 _exit(EXIT_LOGIN_GRACE);
222 }
223
224 /* Destroy the host and server keys. They will no longer be needed. */
225 void
destroy_sensitive_data(void)226 destroy_sensitive_data(void)
227 {
228 u_int i;
229
230 for (i = 0; i < options.num_host_key_files; i++) {
231 if (sensitive_data.host_keys[i]) {
232 sshkey_free(sensitive_data.host_keys[i]);
233 sensitive_data.host_keys[i] = NULL;
234 }
235 if (sensitive_data.host_certificates[i]) {
236 sshkey_free(sensitive_data.host_certificates[i]);
237 sensitive_data.host_certificates[i] = NULL;
238 }
239 }
240 }
241
242 /* Demote private to public keys for network child */
243 void
demote_sensitive_data(void)244 demote_sensitive_data(void)
245 {
246 struct sshkey *tmp;
247 u_int i;
248 int r;
249
250 for (i = 0; i < options.num_host_key_files; i++) {
251 if (sensitive_data.host_keys[i]) {
252 if ((r = sshkey_from_private(
253 sensitive_data.host_keys[i], &tmp)) != 0)
254 fatal_r(r, "could not demote host %s key",
255 sshkey_type(sensitive_data.host_keys[i]));
256 sshkey_free(sensitive_data.host_keys[i]);
257 sensitive_data.host_keys[i] = tmp;
258 }
259 /* Certs do not need demotion */
260 }
261 }
262
263 static void
reseed_prngs(void)264 reseed_prngs(void)
265 {
266 u_int32_t rnd[256];
267
268 #ifdef WITH_OPENSSL
269 RAND_poll();
270 #endif
271 arc4random_stir(); /* noop on recent arc4random() implementations */
272 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
273
274 #ifdef WITH_OPENSSL
275 RAND_seed(rnd, sizeof(rnd));
276 /* give libcrypto a chance to notice the PID change */
277 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
278 fatal("%s: RAND_bytes failed", __func__);
279 #endif
280
281 explicit_bzero(rnd, sizeof(rnd));
282 }
283
284 static void
privsep_preauth_child(void)285 privsep_preauth_child(void)
286 {
287 gid_t gidset[1];
288
289 /* Enable challenge-response authentication for privilege separation */
290 privsep_challenge_enable();
291
292 #ifdef GSSAPI
293 /* Cache supported mechanism OIDs for later use */
294 ssh_gssapi_prepare_supported_oids();
295 #endif
296
297 reseed_prngs();
298
299 /* Demote the private keys to public keys. */
300 demote_sensitive_data();
301
302 /* Demote the child */
303 if (privsep_chroot) {
304 /* Change our root directory */
305 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
306 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
307 strerror(errno));
308 if (chdir("/") == -1)
309 fatal("chdir(\"/\"): %s", strerror(errno));
310
311 /* Drop our privileges */
312 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
313 (u_int)privsep_pw->pw_gid);
314 gidset[0] = privsep_pw->pw_gid;
315 if (setgroups(1, gidset) == -1)
316 fatal("setgroups: %.100s", strerror(errno));
317 permanently_set_uid(privsep_pw);
318 }
319 }
320
321 static int
privsep_preauth(struct ssh * ssh)322 privsep_preauth(struct ssh *ssh)
323 {
324 int status, r;
325 pid_t pid;
326 struct ssh_sandbox *box = NULL;
327
328 /* Set up unprivileged child process to deal with network data */
329 pmonitor = monitor_init();
330 /* Store a pointer to the kex for later rekeying */
331 pmonitor->m_pkex = &ssh->kex;
332
333 box = ssh_sandbox_init(pmonitor);
334 pid = fork();
335 if (pid == -1) {
336 fatal("fork of unprivileged child failed");
337 } else if (pid != 0) {
338 debug2("Network child is on pid %ld", (long)pid);
339
340 pmonitor->m_pid = pid;
341 if (have_agent) {
342 r = ssh_get_authentication_socket(&auth_sock);
343 if (r != 0) {
344 error_r(r, "Could not get agent socket");
345 have_agent = 0;
346 }
347 }
348 if (box != NULL)
349 ssh_sandbox_parent_preauth(box, pid);
350 monitor_child_preauth(ssh, pmonitor);
351
352 /* Wait for the child's exit status */
353 while (waitpid(pid, &status, 0) == -1) {
354 if (errno == EINTR)
355 continue;
356 pmonitor->m_pid = -1;
357 fatal_f("waitpid: %s", strerror(errno));
358 }
359 privsep_is_preauth = 0;
360 pmonitor->m_pid = -1;
361 if (WIFEXITED(status)) {
362 if (WEXITSTATUS(status) != 0)
363 fatal_f("preauth child exited with status %d",
364 WEXITSTATUS(status));
365 } else if (WIFSIGNALED(status))
366 fatal_f("preauth child terminated by signal %d",
367 WTERMSIG(status));
368 if (box != NULL)
369 ssh_sandbox_parent_finish(box);
370 return 1;
371 } else {
372 /* child */
373 close(pmonitor->m_sendfd);
374 close(pmonitor->m_log_recvfd);
375
376 /* Arrange for logging to be sent to the monitor */
377 set_log_handler(mm_log_handler, pmonitor);
378
379 privsep_preauth_child();
380 setproctitle("%s", "[net]");
381 if (box != NULL)
382 ssh_sandbox_child(box);
383
384 return 0;
385 }
386 }
387
388 static void
privsep_postauth(struct ssh * ssh,Authctxt * authctxt)389 privsep_postauth(struct ssh *ssh, Authctxt *authctxt)
390 {
391 int skip_privdrop = 0;
392
393 /*
394 * Hack for systems that don't support FD passing: retain privileges
395 * in the post-auth privsep process so it can allocate PTYs directly.
396 * This is basically equivalent to what we did <= 9.7, which was to
397 * disable post-auth privsep entriely.
398 * Cygwin doesn't need to drop privs here although it doesn't support
399 * fd passing, as AFAIK PTY allocation on this platform doesn't require
400 * special privileges to begin with.
401 */
402 #if defined(DISABLE_FD_PASSING) && !defined(HAVE_CYGWIN)
403 skip_privdrop = 1;
404 #endif
405
406 /* New socket pair */
407 monitor_reinit(pmonitor);
408
409 pmonitor->m_pid = fork();
410 if (pmonitor->m_pid == -1)
411 fatal("fork of unprivileged child failed");
412 else if (pmonitor->m_pid != 0) {
413 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
414 sshbuf_reset(loginmsg);
415 monitor_clear_keystate(ssh, pmonitor);
416 monitor_child_postauth(ssh, pmonitor);
417
418 /* NEVERREACHED */
419 exit(0);
420 }
421
422 /* child */
423
424 close(pmonitor->m_sendfd);
425 pmonitor->m_sendfd = -1;
426
427 /* Demote the private keys to public keys. */
428 demote_sensitive_data();
429
430 reseed_prngs();
431
432 /* Drop privileges */
433 if (!skip_privdrop)
434 do_setusercontext(authctxt->pw);
435
436 /* It is safe now to apply the key state */
437 monitor_apply_keystate(ssh, pmonitor);
438
439 /*
440 * Tell the packet layer that authentication was successful, since
441 * this information is not part of the key state.
442 */
443 ssh_packet_set_authenticated(ssh);
444 }
445
446 static void
append_hostkey_type(struct sshbuf * b,const char * s)447 append_hostkey_type(struct sshbuf *b, const char *s)
448 {
449 int r;
450
451 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
452 debug3_f("%s key not permitted by HostkeyAlgorithms", s);
453 return;
454 }
455 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
456 fatal_fr(r, "sshbuf_putf");
457 }
458
459 static char *
list_hostkey_types(void)460 list_hostkey_types(void)
461 {
462 struct sshbuf *b;
463 struct sshkey *key;
464 char *ret;
465 u_int i;
466
467 if ((b = sshbuf_new()) == NULL)
468 fatal_f("sshbuf_new failed");
469 for (i = 0; i < options.num_host_key_files; i++) {
470 key = sensitive_data.host_keys[i];
471 if (key == NULL)
472 key = sensitive_data.host_pubkeys[i];
473 if (key == NULL)
474 continue;
475 switch (key->type) {
476 case KEY_RSA:
477 /* for RSA we also support SHA2 signatures */
478 append_hostkey_type(b, "rsa-sha2-512");
479 append_hostkey_type(b, "rsa-sha2-256");
480 /* FALLTHROUGH */
481 case KEY_DSA:
482 case KEY_ECDSA:
483 case KEY_ED25519:
484 case KEY_ECDSA_SK:
485 case KEY_ED25519_SK:
486 case KEY_XMSS:
487 append_hostkey_type(b, sshkey_ssh_name(key));
488 break;
489 }
490 /* If the private key has a cert peer, then list that too */
491 key = sensitive_data.host_certificates[i];
492 if (key == NULL)
493 continue;
494 switch (key->type) {
495 case KEY_RSA_CERT:
496 /* for RSA we also support SHA2 signatures */
497 append_hostkey_type(b,
498 "rsa-sha2-512-cert-v01@openssh.com");
499 append_hostkey_type(b,
500 "rsa-sha2-256-cert-v01@openssh.com");
501 /* FALLTHROUGH */
502 case KEY_DSA_CERT:
503 case KEY_ECDSA_CERT:
504 case KEY_ED25519_CERT:
505 case KEY_ECDSA_SK_CERT:
506 case KEY_ED25519_SK_CERT:
507 case KEY_XMSS_CERT:
508 append_hostkey_type(b, sshkey_ssh_name(key));
509 break;
510 }
511 }
512 if ((ret = sshbuf_dup_string(b)) == NULL)
513 fatal_f("sshbuf_dup_string failed");
514 sshbuf_free(b);
515 debug_f("%s", ret);
516 return ret;
517 }
518
519 static struct sshkey *
get_hostkey_by_type(int type,int nid,int need_private,struct ssh * ssh)520 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
521 {
522 u_int i;
523 struct sshkey *key;
524
525 for (i = 0; i < options.num_host_key_files; i++) {
526 switch (type) {
527 case KEY_RSA_CERT:
528 case KEY_DSA_CERT:
529 case KEY_ECDSA_CERT:
530 case KEY_ED25519_CERT:
531 case KEY_ECDSA_SK_CERT:
532 case KEY_ED25519_SK_CERT:
533 case KEY_XMSS_CERT:
534 key = sensitive_data.host_certificates[i];
535 break;
536 default:
537 key = sensitive_data.host_keys[i];
538 if (key == NULL && !need_private)
539 key = sensitive_data.host_pubkeys[i];
540 break;
541 }
542 if (key == NULL || key->type != type)
543 continue;
544 switch (type) {
545 case KEY_ECDSA:
546 case KEY_ECDSA_SK:
547 case KEY_ECDSA_CERT:
548 case KEY_ECDSA_SK_CERT:
549 if (key->ecdsa_nid != nid)
550 continue;
551 /* FALLTHROUGH */
552 default:
553 return need_private ?
554 sensitive_data.host_keys[i] : key;
555 }
556 }
557 return NULL;
558 }
559
560 struct sshkey *
get_hostkey_public_by_type(int type,int nid,struct ssh * ssh)561 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
562 {
563 return get_hostkey_by_type(type, nid, 0, ssh);
564 }
565
566 struct sshkey *
get_hostkey_private_by_type(int type,int nid,struct ssh * ssh)567 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
568 {
569 return get_hostkey_by_type(type, nid, 1, ssh);
570 }
571
572 struct sshkey *
get_hostkey_by_index(int ind)573 get_hostkey_by_index(int ind)
574 {
575 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
576 return (NULL);
577 return (sensitive_data.host_keys[ind]);
578 }
579
580 struct sshkey *
get_hostkey_public_by_index(int ind,struct ssh * ssh)581 get_hostkey_public_by_index(int ind, struct ssh *ssh)
582 {
583 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
584 return (NULL);
585 return (sensitive_data.host_pubkeys[ind]);
586 }
587
588 int
get_hostkey_index(struct sshkey * key,int compare,struct ssh * ssh)589 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
590 {
591 u_int i;
592
593 for (i = 0; i < options.num_host_key_files; i++) {
594 if (sshkey_is_cert(key)) {
595 if (key == sensitive_data.host_certificates[i] ||
596 (compare && sensitive_data.host_certificates[i] &&
597 sshkey_equal(key,
598 sensitive_data.host_certificates[i])))
599 return (i);
600 } else {
601 if (key == sensitive_data.host_keys[i] ||
602 (compare && sensitive_data.host_keys[i] &&
603 sshkey_equal(key, sensitive_data.host_keys[i])))
604 return (i);
605 if (key == sensitive_data.host_pubkeys[i] ||
606 (compare && sensitive_data.host_pubkeys[i] &&
607 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
608 return (i);
609 }
610 }
611 return (-1);
612 }
613
614 /* Inform the client of all hostkeys */
615 static void
notify_hostkeys(struct ssh * ssh)616 notify_hostkeys(struct ssh *ssh)
617 {
618 struct sshbuf *buf;
619 struct sshkey *key;
620 u_int i, nkeys;
621 int r;
622 char *fp;
623
624 /* Some clients cannot cope with the hostkeys message, skip those. */
625 if (ssh->compat & SSH_BUG_HOSTKEYS)
626 return;
627
628 if ((buf = sshbuf_new()) == NULL)
629 fatal_f("sshbuf_new");
630 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
631 key = get_hostkey_public_by_index(i, ssh);
632 if (key == NULL || key->type == KEY_UNSPEC ||
633 sshkey_is_cert(key))
634 continue;
635 fp = sshkey_fingerprint(key, options.fingerprint_hash,
636 SSH_FP_DEFAULT);
637 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp);
638 free(fp);
639 if (nkeys == 0) {
640 /*
641 * Start building the request when we find the
642 * first usable key.
643 */
644 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
645 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 ||
646 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */
647 sshpkt_fatal(ssh, r, "%s: start request", __func__);
648 }
649 /* Append the key to the request */
650 sshbuf_reset(buf);
651 if ((r = sshkey_putb(key, buf)) != 0)
652 fatal_fr(r, "couldn't put hostkey %d", i);
653 if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
654 sshpkt_fatal(ssh, r, "%s: append key", __func__);
655 nkeys++;
656 }
657 debug3_f("sent %u hostkeys", nkeys);
658 if (nkeys == 0)
659 fatal_f("no hostkeys");
660 if ((r = sshpkt_send(ssh)) != 0)
661 sshpkt_fatal(ssh, r, "%s: send", __func__);
662 sshbuf_free(buf);
663 }
664
665 static void
usage(void)666 usage(void)
667 {
668 fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION);
669 fprintf(stderr,
670 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n"
671 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
672 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
673 );
674 exit(1);
675 }
676
677 static void
parse_hostkeys(struct sshbuf * hostkeys)678 parse_hostkeys(struct sshbuf *hostkeys)
679 {
680 int r;
681 u_int num_keys = 0;
682 struct sshkey *k;
683 struct sshbuf *kbuf;
684 const u_char *cp;
685 size_t len;
686
687 while (sshbuf_len(hostkeys) != 0) {
688 if (num_keys > 2048)
689 fatal_f("too many hostkeys");
690 sensitive_data.host_keys = xrecallocarray(
691 sensitive_data.host_keys, num_keys, num_keys + 1,
692 sizeof(*sensitive_data.host_pubkeys));
693 sensitive_data.host_pubkeys = xrecallocarray(
694 sensitive_data.host_pubkeys, num_keys, num_keys + 1,
695 sizeof(*sensitive_data.host_pubkeys));
696 sensitive_data.host_certificates = xrecallocarray(
697 sensitive_data.host_certificates, num_keys, num_keys + 1,
698 sizeof(*sensitive_data.host_certificates));
699 /* private key */
700 k = NULL;
701 if ((r = sshbuf_froms(hostkeys, &kbuf)) != 0)
702 fatal_fr(r, "extract privkey");
703 if (sshbuf_len(kbuf) != 0 &&
704 (r = sshkey_private_deserialize(kbuf, &k)) != 0)
705 fatal_fr(r, "parse pubkey");
706 sensitive_data.host_keys[num_keys] = k;
707 sshbuf_free(kbuf);
708 if (k)
709 debug2_f("privkey %u: %s", num_keys, sshkey_ssh_name(k));
710 /* public key */
711 k = NULL;
712 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
713 fatal_fr(r, "extract pubkey");
714 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
715 fatal_fr(r, "parse pubkey");
716 sensitive_data.host_pubkeys[num_keys] = k;
717 if (k)
718 debug2_f("pubkey %u: %s", num_keys, sshkey_ssh_name(k));
719 /* certificate */
720 k = NULL;
721 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
722 fatal_fr(r, "extract pubkey");
723 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
724 fatal_fr(r, "parse pubkey");
725 sensitive_data.host_certificates[num_keys] = k;
726 if (k)
727 debug2_f("cert %u: %s", num_keys, sshkey_ssh_name(k));
728 num_keys++;
729 }
730 sensitive_data.num_hostkeys = num_keys;
731 }
732
733 static void
recv_rexec_state(int fd,struct sshbuf * conf,uint64_t * timing_secretp)734 recv_rexec_state(int fd, struct sshbuf *conf, uint64_t *timing_secretp)
735 {
736 struct sshbuf *m, *inc, *hostkeys;
737 u_char *cp, ver;
738 size_t len;
739 int r;
740 struct include_item *item;
741
742 debug3_f("entering fd = %d", fd);
743
744 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
745 fatal_f("sshbuf_new failed");
746 if (ssh_msg_recv(fd, m) == -1)
747 fatal_f("ssh_msg_recv failed");
748 if ((r = sshbuf_get_u8(m, &ver)) != 0)
749 fatal_fr(r, "parse version");
750 if (ver != 0)
751 fatal_f("rexec version mismatch");
752 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || /* XXX _direct */
753 (r = sshbuf_get_u64(m, timing_secretp)) != 0 ||
754 (r = sshbuf_froms(m, &hostkeys)) != 0 ||
755 (r = sshbuf_get_stringb(m, inc)) != 0)
756 fatal_fr(r, "parse config");
757
758 if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
759 fatal_fr(r, "sshbuf_put");
760
761 while (sshbuf_len(inc) != 0) {
762 item = xcalloc(1, sizeof(*item));
763 if ((item->contents = sshbuf_new()) == NULL)
764 fatal_f("sshbuf_new failed");
765 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
766 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
767 (r = sshbuf_get_stringb(inc, item->contents)) != 0)
768 fatal_fr(r, "parse includes");
769 TAILQ_INSERT_TAIL(&includes, item, entry);
770 }
771
772 parse_hostkeys(hostkeys);
773
774 free(cp);
775 sshbuf_free(m);
776 sshbuf_free(hostkeys);
777 sshbuf_free(inc);
778
779 debug3_f("done");
780 }
781
782 /*
783 * If IP options are supported, make sure there are none (log and
784 * return an error if any are found). Basically we are worried about
785 * source routing; it can be used to pretend you are somebody
786 * (ip-address) you are not. That itself may be "almost acceptable"
787 * under certain circumstances, but rhosts authentication is useless
788 * if source routing is accepted. Notice also that if we just dropped
789 * source routing here, the other side could use IP spoofing to do
790 * rest of the interaction and could still bypass security. So we
791 * exit here if we detect any IP options.
792 */
793 static void
check_ip_options(struct ssh * ssh)794 check_ip_options(struct ssh *ssh)
795 {
796 #ifdef IP_OPTIONS
797 int sock_in = ssh_packet_get_connection_in(ssh);
798 struct sockaddr_storage from;
799 u_char opts[200];
800 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
801 char text[sizeof(opts) * 3 + 1];
802
803 memset(&from, 0, sizeof(from));
804 if (getpeername(sock_in, (struct sockaddr *)&from,
805 &fromlen) == -1)
806 return;
807 if (from.ss_family != AF_INET)
808 return;
809 /* XXX IPv6 options? */
810
811 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
812 &option_size) >= 0 && option_size != 0) {
813 text[0] = '\0';
814 for (i = 0; i < option_size; i++)
815 snprintf(text + i*3, sizeof(text) - i*3,
816 " %2.2x", opts[i]);
817 fatal("Connection from %.100s port %d with IP opts: %.800s",
818 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
819 }
820 return;
821 #endif /* IP_OPTIONS */
822 }
823
824 /* Set the routing domain for this process */
825 static void
set_process_rdomain(struct ssh * ssh,const char * name)826 set_process_rdomain(struct ssh *ssh, const char *name)
827 {
828 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
829 if (name == NULL)
830 return; /* default */
831
832 if (strcmp(name, "%D") == 0) {
833 /* "expands" to routing domain of connection */
834 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
835 return;
836 }
837 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
838 return sys_set_process_rdomain(name);
839 #elif defined(__OpenBSD__)
840 int rtable, ortable = getrtable();
841 const char *errstr;
842
843 if (name == NULL)
844 return; /* default */
845
846 if (strcmp(name, "%D") == 0) {
847 /* "expands" to routing domain of connection */
848 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
849 return;
850 }
851
852 rtable = (int)strtonum(name, 0, 255, &errstr);
853 if (errstr != NULL) /* Shouldn't happen */
854 fatal("Invalid routing domain \"%s\": %s", name, errstr);
855 if (rtable != ortable && setrtable(rtable) != 0)
856 fatal("Unable to set routing domain %d: %s",
857 rtable, strerror(errno));
858 debug_f("set routing domain %d (was %d)", rtable, ortable);
859 #else /* defined(__OpenBSD__) */
860 fatal("Unable to set routing domain: not supported in this platform");
861 #endif
862 }
863
864 /*
865 * Main program for the daemon.
866 */
867 int
main(int ac,char ** av)868 main(int ac, char **av)
869 {
870 struct ssh *ssh = NULL;
871 extern char *optarg;
872 extern int optind;
873 int r, opt, on = 1, remote_port;
874 int sock_in = -1, sock_out = -1, rexeced_flag = 0, have_key = 0;
875 const char *remote_ip, *rdomain;
876 char *line, *laddr, *logfile = NULL;
877 u_int i;
878 u_int64_t ibytes, obytes;
879 mode_t new_umask;
880 Authctxt *authctxt;
881 struct connection_info *connection_info = NULL;
882 sigset_t sigmask;
883 uint64_t timing_secret = 0;
884
885 sigemptyset(&sigmask);
886 sigprocmask(SIG_SETMASK, &sigmask, NULL);
887
888 #ifdef HAVE_SECUREWARE
889 (void)set_auth_parameters(ac, av);
890 #endif
891 __progname = ssh_get_progname(av[0]);
892
893 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
894 saved_argc = ac;
895 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
896 for (i = 0; (int)i < ac; i++)
897 saved_argv[i] = xstrdup(av[i]);
898 saved_argv[i] = NULL;
899
900 #ifndef HAVE_SETPROCTITLE
901 /* Prepare for later setproctitle emulation */
902 compat_init_setproctitle(ac, av);
903 av = saved_argv;
904 #endif
905
906 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
907 sanitise_stdfd();
908
909 /* Initialize configuration options to their default values. */
910 initialize_server_options(&options);
911
912 /* Parse command-line arguments. */
913 while ((opt = getopt(ac, av,
914 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) {
915 switch (opt) {
916 case '4':
917 options.address_family = AF_INET;
918 break;
919 case '6':
920 options.address_family = AF_INET6;
921 break;
922 case 'f':
923 config_file_name = optarg;
924 break;
925 case 'c':
926 servconf_add_hostcert("[command-line]", 0,
927 &options, optarg);
928 break;
929 case 'd':
930 if (debug_flag == 0) {
931 debug_flag = 1;
932 options.log_level = SYSLOG_LEVEL_DEBUG1;
933 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
934 options.log_level++;
935 break;
936 case 'D':
937 /* ignore */
938 break;
939 case 'E':
940 logfile = optarg;
941 /* FALLTHROUGH */
942 case 'e':
943 log_stderr = 1;
944 break;
945 case 'i':
946 inetd_flag = 1;
947 break;
948 case 'r':
949 /* ignore */
950 break;
951 case 'R':
952 rexeced_flag = 1;
953 break;
954 case 'Q':
955 /* ignored */
956 break;
957 case 'q':
958 options.log_level = SYSLOG_LEVEL_QUIET;
959 break;
960 case 'b':
961 /* protocol 1, ignored */
962 break;
963 case 'p':
964 options.ports_from_cmdline = 1;
965 if (options.num_ports >= MAX_PORTS) {
966 fprintf(stderr, "too many ports.\n");
967 exit(1);
968 }
969 options.ports[options.num_ports++] = a2port(optarg);
970 if (options.ports[options.num_ports-1] <= 0) {
971 fprintf(stderr, "Bad port number.\n");
972 exit(1);
973 }
974 break;
975 case 'g':
976 if ((options.login_grace_time = convtime(optarg)) == -1) {
977 fprintf(stderr, "Invalid login grace time.\n");
978 exit(1);
979 }
980 break;
981 case 'k':
982 /* protocol 1, ignored */
983 break;
984 case 'h':
985 servconf_add_hostkey("[command-line]", 0,
986 &options, optarg, 1);
987 break;
988 case 't':
989 case 'T':
990 case 'G':
991 fatal("test/dump modes not supported");
992 break;
993 case 'C':
994 connection_info = server_get_connection_info(ssh, 0, 0);
995 if (parse_server_match_testspec(connection_info,
996 optarg) == -1)
997 exit(1);
998 break;
999 case 'u':
1000 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1001 if (utmp_len > HOST_NAME_MAX+1) {
1002 fprintf(stderr, "Invalid utmp length.\n");
1003 exit(1);
1004 }
1005 break;
1006 case 'o':
1007 line = xstrdup(optarg);
1008 if (process_server_config_line(&options, line,
1009 "command-line", 0, NULL, NULL, &includes) != 0)
1010 exit(1);
1011 free(line);
1012 break;
1013 case 'V':
1014 fprintf(stderr, "%s, %s\n",
1015 SSH_RELEASE, SSH_OPENSSL_VERSION);
1016 exit(0);
1017 default:
1018 usage();
1019 break;
1020 }
1021 }
1022
1023 /* Check that there are no remaining arguments. */
1024 if (optind < ac) {
1025 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1026 exit(1);
1027 }
1028
1029 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1030
1031 if (!rexeced_flag)
1032 fatal("sshd-session should not be executed directly");
1033
1034 closefrom(REEXEC_MIN_FREE_FD);
1035
1036 seed_rng();
1037
1038 /* If requested, redirect the logs to the specified logfile. */
1039 if (logfile != NULL) {
1040 char *cp, pid_s[32];
1041
1042 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
1043 cp = percent_expand(logfile,
1044 "p", pid_s,
1045 "P", "sshd-session",
1046 (char *)NULL);
1047 log_redirect_stderr_to(cp);
1048 free(cp);
1049 }
1050
1051 /*
1052 * Force logging to stderr until we have loaded the private host
1053 * key (unless started from inetd)
1054 */
1055 log_init(__progname,
1056 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1057 SYSLOG_LEVEL_INFO : options.log_level,
1058 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1059 SYSLOG_FACILITY_AUTH : options.log_facility,
1060 log_stderr || !inetd_flag || debug_flag);
1061
1062 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1063
1064 /* Fetch our configuration */
1065 if ((cfg = sshbuf_new()) == NULL)
1066 fatal("sshbuf_new config buf failed");
1067 setproctitle("%s", "[rexeced]");
1068 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg, &timing_secret);
1069 close(REEXEC_CONFIG_PASS_FD);
1070 parse_server_config(&options, "rexec", cfg, &includes, NULL, 1);
1071 /* Fill in default values for those options not explicitly set. */
1072 fill_default_server_options(&options);
1073 options.timing_secret = timing_secret;
1074
1075 /* Store privilege separation user for later use if required. */
1076 privsep_chroot = (getuid() == 0 || geteuid() == 0);
1077 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1078 if (privsep_chroot || options.kerberos_authentication)
1079 fatal("Privilege separation user %s does not exist",
1080 SSH_PRIVSEP_USER);
1081 } else {
1082 privsep_pw = pwcopy(privsep_pw);
1083 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1084 privsep_pw->pw_passwd = xstrdup("*");
1085 }
1086 endpwent();
1087
1088 if (!debug_flag) {
1089 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1090 close(REEXEC_STARTUP_PIPE_FD);
1091 /*
1092 * Signal parent that this child is at a point where
1093 * they can go away if they have a SIGHUP pending.
1094 */
1095 (void)atomicio(vwrite, startup_pipe, "\0", 1);
1096 }
1097
1098 /* Check that options are sensible */
1099 if (options.authorized_keys_command_user == NULL &&
1100 (options.authorized_keys_command != NULL &&
1101 strcasecmp(options.authorized_keys_command, "none") != 0))
1102 fatal("AuthorizedKeysCommand set without "
1103 "AuthorizedKeysCommandUser");
1104 if (options.authorized_principals_command_user == NULL &&
1105 (options.authorized_principals_command != NULL &&
1106 strcasecmp(options.authorized_principals_command, "none") != 0))
1107 fatal("AuthorizedPrincipalsCommand set without "
1108 "AuthorizedPrincipalsCommandUser");
1109
1110 /*
1111 * Check whether there is any path through configured auth methods.
1112 * Unfortunately it is not possible to verify this generally before
1113 * daemonisation in the presence of Match block, but this catches
1114 * and warns for trivial misconfigurations that could break login.
1115 */
1116 if (options.num_auth_methods != 0) {
1117 for (i = 0; i < options.num_auth_methods; i++) {
1118 if (auth2_methods_valid(options.auth_methods[i],
1119 1) == 0)
1120 break;
1121 }
1122 if (i >= options.num_auth_methods)
1123 fatal("AuthenticationMethods cannot be satisfied by "
1124 "enabled authentication methods");
1125 }
1126
1127 #ifdef WITH_OPENSSL
1128 if (options.moduli_file != NULL)
1129 dh_set_moduli_file(options.moduli_file);
1130 #endif
1131
1132 if (options.host_key_agent) {
1133 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1134 setenv(SSH_AUTHSOCKET_ENV_NAME,
1135 options.host_key_agent, 1);
1136 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1137 have_agent = 1;
1138 else
1139 error_r(r, "Could not connect to agent \"%s\"",
1140 options.host_key_agent);
1141 }
1142
1143 if (options.num_host_key_files != sensitive_data.num_hostkeys) {
1144 fatal("internal error: hostkeys confused (config %u recvd %u)",
1145 options.num_host_key_files, sensitive_data.num_hostkeys);
1146 }
1147
1148 for (i = 0; i < options.num_host_key_files; i++) {
1149 if (sensitive_data.host_keys[i] != NULL ||
1150 (have_agent && sensitive_data.host_pubkeys[i] != NULL)) {
1151 have_key = 1;
1152 break;
1153 }
1154 }
1155 if (!have_key)
1156 fatal("internal error: monitor received no hostkeys");
1157
1158 /* Ensure that umask disallows at least group and world write */
1159 new_umask = umask(0077) | 0022;
1160 (void) umask(new_umask);
1161
1162 /* Initialize the log (it is reinitialized below in case we forked). */
1163 if (debug_flag)
1164 log_stderr = 1;
1165 log_init(__progname, options.log_level,
1166 options.log_facility, log_stderr);
1167 for (i = 0; i < options.num_log_verbose; i++)
1168 log_verbose_add(options.log_verbose[i]);
1169
1170 /* Reinitialize the log (because of the fork above). */
1171 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1172
1173 /*
1174 * Chdir to the root directory so that the current disk can be
1175 * unmounted if desired.
1176 */
1177 if (chdir("/") == -1)
1178 error("chdir(\"/\"): %s", strerror(errno));
1179
1180 /* ignore SIGPIPE */
1181 ssh_signal(SIGPIPE, SIG_IGN);
1182
1183 /* Get a connection, either from inetd or rexec */
1184 if (inetd_flag) {
1185 /*
1186 * NB. must be different fd numbers for the !socket case,
1187 * as packet_connection_is_on_socket() depends on this.
1188 */
1189 sock_in = dup(STDIN_FILENO);
1190 sock_out = dup(STDOUT_FILENO);
1191 } else {
1192 /* rexec case; accept()ed socket in ancestor listener */
1193 sock_in = sock_out = dup(STDIN_FILENO);
1194 }
1195
1196 /*
1197 * We intentionally do not close the descriptors 0, 1, and 2
1198 * as our code for setting the descriptors won't work if
1199 * ttyfd happens to be one of those.
1200 */
1201 if (stdfd_devnull(1, 1, !log_stderr) == -1)
1202 error("stdfd_devnull failed");
1203 debug("network sockets: %d, %d", sock_in, sock_out);
1204
1205 /* This is the child processing a new connection. */
1206 setproctitle("%s", "[accepted]");
1207
1208 /* Executed child processes don't need these. */
1209 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1210 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1211
1212 /* We will not restart on SIGHUP since it no longer makes sense. */
1213 ssh_signal(SIGALRM, SIG_DFL);
1214 ssh_signal(SIGHUP, SIG_DFL);
1215 ssh_signal(SIGTERM, SIG_DFL);
1216 ssh_signal(SIGQUIT, SIG_DFL);
1217 ssh_signal(SIGCHLD, SIG_DFL);
1218 ssh_signal(SIGINT, SIG_DFL);
1219
1220 /*
1221 * Register our connection. This turns encryption off because we do
1222 * not have a key.
1223 */
1224 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
1225 fatal("Unable to create connection");
1226 the_active_state = ssh;
1227 ssh_packet_set_server(ssh);
1228
1229 check_ip_options(ssh);
1230
1231 /* Prepare the channels layer */
1232 channel_init_channels(ssh);
1233 channel_set_af(ssh, options.address_family);
1234 server_process_channel_timeouts(ssh);
1235 server_process_permitopen(ssh);
1236
1237 /* Set SO_KEEPALIVE if requested. */
1238 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) &&
1239 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1)
1240 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1241
1242 if ((remote_port = ssh_remote_port(ssh)) < 0) {
1243 debug("ssh_remote_port failed");
1244 cleanup_exit(255);
1245 }
1246
1247 /*
1248 * The rest of the code depends on the fact that
1249 * ssh_remote_ipaddr() caches the remote ip, even if
1250 * the socket goes away.
1251 */
1252 remote_ip = ssh_remote_ipaddr(ssh);
1253
1254 #ifdef SSH_AUDIT_EVENTS
1255 audit_connection_from(remote_ip, remote_port);
1256 #endif
1257
1258 rdomain = ssh_packet_rdomain_in(ssh);
1259
1260 /* Log the connection. */
1261 laddr = get_local_ipaddr(sock_in);
1262 verbose("Connection from %s port %d on %s port %d%s%s%s",
1263 remote_ip, remote_port, laddr, ssh_local_port(ssh),
1264 rdomain == NULL ? "" : " rdomain \"",
1265 rdomain == NULL ? "" : rdomain,
1266 rdomain == NULL ? "" : "\"");
1267 free(laddr);
1268
1269 /*
1270 * We don't want to listen forever unless the other side
1271 * successfully authenticates itself. So we set up an alarm which is
1272 * cleared after successful authentication. A limit of zero
1273 * indicates no limit. Note that we don't set the alarm in debugging
1274 * mode; it is just annoying to have the server exit just when you
1275 * are about to discover the bug.
1276 */
1277 ssh_signal(SIGALRM, grace_alarm_handler);
1278 if (!debug_flag)
1279 alarm(options.login_grace_time);
1280
1281 if ((r = kex_exchange_identification(ssh, -1,
1282 options.version_addendum)) != 0)
1283 sshpkt_fatal(ssh, r, "banner exchange");
1284
1285 ssh_packet_set_nonblocking(ssh);
1286
1287 /* allocate authentication context */
1288 authctxt = xcalloc(1, sizeof(*authctxt));
1289 ssh->authctxt = authctxt;
1290
1291 /* XXX global for cleanup, access from other modules */
1292 the_authctxt = authctxt;
1293
1294 /* Set default key authentication options */
1295 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
1296 fatal("allocation failed");
1297
1298 /* prepare buffer to collect messages to display to user after login */
1299 if ((loginmsg = sshbuf_new()) == NULL)
1300 fatal("sshbuf_new loginmsg failed");
1301 auth_debug_reset();
1302
1303 if (privsep_preauth(ssh) == 1)
1304 goto authenticated;
1305
1306 /* perform the key exchange */
1307 /* authenticate user and start session */
1308 do_ssh2_kex(ssh);
1309 do_authentication2(ssh);
1310
1311 /*
1312 * The unprivileged child now transfers the current keystate and exits.
1313 */
1314 mm_send_keystate(ssh, pmonitor);
1315 ssh_packet_clear_keys(ssh);
1316 exit(0);
1317
1318 authenticated:
1319 /*
1320 * Cancel the alarm we set to limit the time taken for
1321 * authentication.
1322 */
1323 alarm(0);
1324 ssh_signal(SIGALRM, SIG_DFL);
1325 authctxt->authenticated = 1;
1326 if (startup_pipe != -1) {
1327 /* signal listener that authentication completed successfully */
1328 (void)atomicio(vwrite, startup_pipe, "\001", 1);
1329 close(startup_pipe);
1330 startup_pipe = -1;
1331 }
1332
1333 if (options.routing_domain != NULL)
1334 set_process_rdomain(ssh, options.routing_domain);
1335
1336 #ifdef SSH_AUDIT_EVENTS
1337 audit_event(ssh, SSH_AUTH_SUCCESS);
1338 #endif
1339
1340 #ifdef GSSAPI
1341 if (options.gss_authentication) {
1342 temporarily_use_uid(authctxt->pw);
1343 ssh_gssapi_storecreds();
1344 restore_uid();
1345 }
1346 #endif
1347 #ifdef USE_PAM
1348 if (options.use_pam) {
1349 do_pam_setcred();
1350 do_pam_session(ssh);
1351 }
1352 #endif
1353
1354 /*
1355 * In privilege separation, we fork another child and prepare
1356 * file descriptor passing.
1357 */
1358 privsep_postauth(ssh, authctxt);
1359 /* the monitor process [priv] will not return */
1360
1361 ssh_packet_set_timeout(ssh, options.client_alive_interval,
1362 options.client_alive_count_max);
1363
1364 /* Try to send all our hostkeys to the client */
1365 notify_hostkeys(ssh);
1366
1367 /* Start session. */
1368 do_authenticated(ssh, authctxt);
1369
1370 /* The connection has been terminated. */
1371 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
1372 verbose("Transferred: sent %llu, received %llu bytes",
1373 (unsigned long long)obytes, (unsigned long long)ibytes);
1374
1375 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1376
1377 #ifdef USE_PAM
1378 if (options.use_pam)
1379 finish_pam();
1380 #endif /* USE_PAM */
1381
1382 #ifdef SSH_AUDIT_EVENTS
1383 mm_audit_event(ssh, SSH_CONNECTION_CLOSE);
1384 #endif
1385
1386 ssh_packet_close(ssh);
1387
1388 mm_terminate();
1389
1390 exit(0);
1391 }
1392
1393 int
sshd_hostkey_sign(struct ssh * ssh,struct sshkey * privkey,struct sshkey * pubkey,u_char ** signature,size_t * slenp,const u_char * data,size_t dlen,const char * alg)1394 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
1395 struct sshkey *pubkey, u_char **signature, size_t *slenp,
1396 const u_char *data, size_t dlen, const char *alg)
1397 {
1398 if (privkey) {
1399 if (mm_sshkey_sign(ssh, privkey, signature, slenp,
1400 data, dlen, alg, options.sk_provider, NULL,
1401 ssh->compat) < 0)
1402 fatal_f("privkey sign failed");
1403 } else {
1404 if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
1405 data, dlen, alg, options.sk_provider, NULL,
1406 ssh->compat) < 0)
1407 fatal_f("pubkey sign failed");
1408 }
1409 return 0;
1410 }
1411
1412 /* SSH2 key exchange */
1413 static void
do_ssh2_kex(struct ssh * ssh)1414 do_ssh2_kex(struct ssh *ssh)
1415 {
1416 char *hkalgs = NULL, *myproposal[PROPOSAL_MAX];
1417 const char *compression = NULL;
1418 struct kex *kex;
1419 int r;
1420
1421 if (options.rekey_limit || options.rekey_interval)
1422 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
1423 options.rekey_interval);
1424
1425 if (options.compression == COMP_NONE)
1426 compression = "none";
1427 hkalgs = list_hostkey_types();
1428
1429 kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms,
1430 options.ciphers, options.macs, compression, hkalgs);
1431
1432 free(hkalgs);
1433
1434 /* start key exchange */
1435 if ((r = kex_setup(ssh, myproposal)) != 0)
1436 fatal_r(r, "kex_setup");
1437 kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
1438 kex = ssh->kex;
1439
1440 #ifdef WITH_OPENSSL
1441 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1442 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1443 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1444 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1445 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1446 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1447 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1448 #ifdef OPENSSL_HAS_ECC
1449 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1450 #endif
1451 #endif
1452 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1453 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1454 kex->load_host_public_key=&get_hostkey_public_by_type;
1455 kex->load_host_private_key=&get_hostkey_private_by_type;
1456 kex->host_key_index=&get_hostkey_index;
1457 kex->sign = sshd_hostkey_sign;
1458
1459 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
1460 kex_proposal_free_entries(myproposal);
1461
1462 #ifdef DEBUG_KEXDH
1463 /* send 1st encrypted/maced/compressed message */
1464 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
1465 (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
1466 (r = sshpkt_send(ssh)) != 0 ||
1467 (r = ssh_packet_write_wait(ssh)) != 0)
1468 fatal_fr(r, "send test");
1469 #endif
1470 debug("KEX done");
1471 }
1472
1473 /* server specific fatal cleanup */
1474 void
cleanup_exit(int i)1475 cleanup_exit(int i)
1476 {
1477 extern int auth_attempted; /* monitor.c */
1478
1479 if (the_active_state != NULL && the_authctxt != NULL) {
1480 do_cleanup(the_active_state, the_authctxt);
1481 if (privsep_is_preauth &&
1482 pmonitor != NULL && pmonitor->m_pid > 1) {
1483 debug("Killing privsep child %d", pmonitor->m_pid);
1484 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
1485 errno != ESRCH) {
1486 error_f("kill(%d): %s", pmonitor->m_pid,
1487 strerror(errno));
1488 }
1489 }
1490 }
1491 /* Override default fatal exit value when auth was attempted */
1492 if (i == 255 && auth_attempted)
1493 _exit(EXIT_AUTH_ATTEMPTED);
1494 #ifdef SSH_AUDIT_EVENTS
1495 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
1496 if (the_active_state != NULL && mm_is_monitor())
1497 audit_event(the_active_state, SSH_CONNECTION_ABANDON);
1498 #endif
1499 _exit(i);
1500 }
1501