1 /* $OpenBSD: sshd-session.c,v 1.9 2024/09/09 02:39:57 djm 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 #include "blacklist_client.h"
113
114 /* Re-exec fds */
115 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
116 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
117 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
118 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
119
120 extern char *__progname;
121
122 /* Server configuration options. */
123 ServerOptions options;
124
125 /* Name of the server configuration file. */
126 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
127
128 /*
129 * Debug mode flag. This can be set on the command line. If debug
130 * mode is enabled, extra debugging output will be sent to the system
131 * log, the daemon will not go to background, and will exit after processing
132 * the first connection.
133 */
134 int debug_flag = 0;
135
136 /* Flag indicating that the daemon is being started from inetd. */
137 static int inetd_flag = 0;
138
139 /* debug goes to stderr unless inetd_flag is set */
140 static int log_stderr = 0;
141
142 /* Saved arguments to main(). */
143 static char **saved_argv;
144 static int saved_argc;
145
146 /* Daemon's agent connection */
147 int auth_sock = -1;
148 static int have_agent = 0;
149
150 /*
151 * Any really sensitive data in the application is contained in this
152 * structure. The idea is that this structure could be locked into memory so
153 * that the pages do not get written into swap. However, there are some
154 * problems. The private key contains BIGNUMs, and we do not (in principle)
155 * have access to the internals of them, and locking just the structure is
156 * not very useful. Currently, memory locking is not implemented.
157 */
158 struct {
159 u_int num_hostkeys;
160 struct sshkey **host_keys; /* all private host keys */
161 struct sshkey **host_pubkeys; /* all public host keys */
162 struct sshkey **host_certificates; /* all public host certificates */
163 } sensitive_data;
164
165 /* record remote hostname or ip */
166 u_int utmp_len = HOST_NAME_MAX+1;
167
168 static int startup_pipe = -1; /* in child */
169
170 /* variables used for privilege separation */
171 struct monitor *pmonitor = NULL;
172 int privsep_is_preauth = 1;
173 static int privsep_chroot = 1;
174
175 /* Unprivileged user */
176 struct passwd *privsep_pw = NULL;
177
178 /* global connection state and authentication contexts */
179 Authctxt *the_authctxt = NULL;
180 struct ssh *the_active_state;
181
182 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */
183 struct sshauthopt *auth_opts = NULL;
184
185 /* sshd_config buffer */
186 struct sshbuf *cfg;
187
188 /* Included files from the configuration file */
189 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
190
191 /* message to be displayed after login */
192 struct sshbuf *loginmsg;
193
194 /* Prototypes for various functions defined later in this file. */
195 void destroy_sensitive_data(void);
196 void demote_sensitive_data(void);
197 static void do_ssh2_kex(struct ssh *);
198
199 /*
200 * Signal handler for the alarm after the login grace period has expired.
201 * As usual, this may only take signal-safe actions, even though it is
202 * terminal.
203 */
204 static void
grace_alarm_handler(int sig)205 grace_alarm_handler(int sig)
206 {
207 /*
208 * Try to kill any processes that we have spawned, E.g. authorized
209 * keys command helpers or privsep children.
210 */
211 if (getpgid(0) == getpid()) {
212 struct sigaction sa;
213
214 /* mask all other signals while in handler */
215 memset(&sa, 0, sizeof(sa));
216 sa.sa_handler = SIG_IGN;
217 sigfillset(&sa.sa_mask);
218 #if defined(SA_RESTART)
219 sa.sa_flags = SA_RESTART;
220 #endif
221 (void)sigaction(SIGTERM, &sa, NULL);
222 kill(0, SIGTERM);
223 }
224 _exit(EXIT_LOGIN_GRACE);
225 }
226
227 /* Destroy the host and server keys. They will no longer be needed. */
228 void
destroy_sensitive_data(void)229 destroy_sensitive_data(void)
230 {
231 u_int i;
232
233 for (i = 0; i < options.num_host_key_files; i++) {
234 if (sensitive_data.host_keys[i]) {
235 sshkey_free(sensitive_data.host_keys[i]);
236 sensitive_data.host_keys[i] = NULL;
237 }
238 if (sensitive_data.host_certificates[i]) {
239 sshkey_free(sensitive_data.host_certificates[i]);
240 sensitive_data.host_certificates[i] = NULL;
241 }
242 }
243 }
244
245 /* Demote private to public keys for network child */
246 void
demote_sensitive_data(void)247 demote_sensitive_data(void)
248 {
249 struct sshkey *tmp;
250 u_int i;
251 int r;
252
253 for (i = 0; i < options.num_host_key_files; i++) {
254 if (sensitive_data.host_keys[i]) {
255 if ((r = sshkey_from_private(
256 sensitive_data.host_keys[i], &tmp)) != 0)
257 fatal_r(r, "could not demote host %s key",
258 sshkey_type(sensitive_data.host_keys[i]));
259 sshkey_free(sensitive_data.host_keys[i]);
260 sensitive_data.host_keys[i] = tmp;
261 }
262 /* Certs do not need demotion */
263 }
264 }
265
266 static void
reseed_prngs(void)267 reseed_prngs(void)
268 {
269 u_int32_t rnd[256];
270
271 #ifdef WITH_OPENSSL
272 RAND_poll();
273 #endif
274 arc4random_stir(); /* noop on recent arc4random() implementations */
275 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */
276
277 #ifdef WITH_OPENSSL
278 RAND_seed(rnd, sizeof(rnd));
279 /* give libcrypto a chance to notice the PID change */
280 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
281 fatal("%s: RAND_bytes failed", __func__);
282 #endif
283
284 explicit_bzero(rnd, sizeof(rnd));
285 }
286
287 static void
privsep_preauth_child(void)288 privsep_preauth_child(void)
289 {
290 gid_t gidset[1];
291
292 /* Enable challenge-response authentication for privilege separation */
293 privsep_challenge_enable();
294
295 #ifdef GSSAPI
296 /* Cache supported mechanism OIDs for later use */
297 ssh_gssapi_prepare_supported_oids();
298 #endif
299
300 reseed_prngs();
301
302 /* Demote the private keys to public keys. */
303 demote_sensitive_data();
304
305 /* Demote the child */
306 if (privsep_chroot) {
307 /* Change our root directory */
308 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
309 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
310 strerror(errno));
311 if (chdir("/") == -1)
312 fatal("chdir(\"/\"): %s", strerror(errno));
313
314 /* Drop our privileges */
315 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid,
316 (u_int)privsep_pw->pw_gid);
317 gidset[0] = privsep_pw->pw_gid;
318 if (setgroups(1, gidset) == -1)
319 fatal("setgroups: %.100s", strerror(errno));
320 permanently_set_uid(privsep_pw);
321 }
322 }
323
324 static int
privsep_preauth(struct ssh * ssh)325 privsep_preauth(struct ssh *ssh)
326 {
327 int status, r;
328 pid_t pid;
329 struct ssh_sandbox *box = NULL;
330
331 /* Set up unprivileged child process to deal with network data */
332 pmonitor = monitor_init();
333 /* Store a pointer to the kex for later rekeying */
334 pmonitor->m_pkex = &ssh->kex;
335
336 box = ssh_sandbox_init(pmonitor);
337 pid = fork();
338 if (pid == -1) {
339 fatal("fork of unprivileged child failed");
340 } else if (pid != 0) {
341 debug2("Network child is on pid %ld", (long)pid);
342
343 pmonitor->m_pid = pid;
344 if (have_agent) {
345 r = ssh_get_authentication_socket(&auth_sock);
346 if (r != 0) {
347 error_r(r, "Could not get agent socket");
348 have_agent = 0;
349 }
350 }
351 if (box != NULL)
352 ssh_sandbox_parent_preauth(box, pid);
353 monitor_child_preauth(ssh, pmonitor);
354
355 /* Wait for the child's exit status */
356 while (waitpid(pid, &status, 0) == -1) {
357 if (errno == EINTR)
358 continue;
359 pmonitor->m_pid = -1;
360 fatal_f("waitpid: %s", strerror(errno));
361 }
362 privsep_is_preauth = 0;
363 pmonitor->m_pid = -1;
364 if (WIFEXITED(status)) {
365 if (WEXITSTATUS(status) != 0)
366 fatal_f("preauth child exited with status %d",
367 WEXITSTATUS(status));
368 } else if (WIFSIGNALED(status))
369 fatal_f("preauth child terminated by signal %d",
370 WTERMSIG(status));
371 if (box != NULL)
372 ssh_sandbox_parent_finish(box);
373 return 1;
374 } else {
375 /* child */
376 close(pmonitor->m_sendfd);
377 close(pmonitor->m_log_recvfd);
378
379 /* Arrange for logging to be sent to the monitor */
380 set_log_handler(mm_log_handler, pmonitor);
381
382 privsep_preauth_child();
383 setproctitle("%s", "[net]");
384 if (box != NULL)
385 ssh_sandbox_child(box);
386
387 return 0;
388 }
389 }
390
391 static void
privsep_postauth(struct ssh * ssh,Authctxt * authctxt)392 privsep_postauth(struct ssh *ssh, Authctxt *authctxt)
393 {
394 int skip_privdrop = 0;
395
396 /*
397 * Hack for systems that don't support FD passing: retain privileges
398 * in the post-auth privsep process so it can allocate PTYs directly.
399 * This is basically equivalent to what we did <= 9.7, which was to
400 * disable post-auth privsep entriely.
401 * Cygwin doesn't need to drop privs here although it doesn't support
402 * fd passing, as AFAIK PTY allocation on this platform doesn't require
403 * special privileges to begin with.
404 */
405 #if defined(DISABLE_FD_PASSING) && !defined(HAVE_CYGWIN)
406 skip_privdrop = 1;
407 #endif
408
409 /* New socket pair */
410 monitor_reinit(pmonitor);
411
412 pmonitor->m_pid = fork();
413 if (pmonitor->m_pid == -1)
414 fatal("fork of unprivileged child failed");
415 else if (pmonitor->m_pid != 0) {
416 verbose("User child is on pid %ld", (long)pmonitor->m_pid);
417 sshbuf_reset(loginmsg);
418 monitor_clear_keystate(ssh, pmonitor);
419 monitor_child_postauth(ssh, pmonitor);
420
421 /* NEVERREACHED */
422 exit(0);
423 }
424
425 /* child */
426
427 close(pmonitor->m_sendfd);
428 pmonitor->m_sendfd = -1;
429
430 /* Demote the private keys to public keys. */
431 demote_sensitive_data();
432
433 reseed_prngs();
434
435 /* Drop privileges */
436 if (!skip_privdrop)
437 do_setusercontext(authctxt->pw);
438
439 /* It is safe now to apply the key state */
440 monitor_apply_keystate(ssh, pmonitor);
441
442 /*
443 * Tell the packet layer that authentication was successful, since
444 * this information is not part of the key state.
445 */
446 ssh_packet_set_authenticated(ssh);
447 }
448
449 static void
append_hostkey_type(struct sshbuf * b,const char * s)450 append_hostkey_type(struct sshbuf *b, const char *s)
451 {
452 int r;
453
454 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) {
455 debug3_f("%s key not permitted by HostkeyAlgorithms", s);
456 return;
457 }
458 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0)
459 fatal_fr(r, "sshbuf_putf");
460 }
461
462 static char *
list_hostkey_types(void)463 list_hostkey_types(void)
464 {
465 struct sshbuf *b;
466 struct sshkey *key;
467 char *ret;
468 u_int i;
469
470 if ((b = sshbuf_new()) == NULL)
471 fatal_f("sshbuf_new failed");
472 for (i = 0; i < options.num_host_key_files; i++) {
473 key = sensitive_data.host_keys[i];
474 if (key == NULL)
475 key = sensitive_data.host_pubkeys[i];
476 if (key == NULL)
477 continue;
478 switch (key->type) {
479 case KEY_RSA:
480 /* for RSA we also support SHA2 signatures */
481 append_hostkey_type(b, "rsa-sha2-512");
482 append_hostkey_type(b, "rsa-sha2-256");
483 /* FALLTHROUGH */
484 case KEY_DSA:
485 case KEY_ECDSA:
486 case KEY_ED25519:
487 case KEY_ECDSA_SK:
488 case KEY_ED25519_SK:
489 case KEY_XMSS:
490 append_hostkey_type(b, sshkey_ssh_name(key));
491 break;
492 }
493 /* If the private key has a cert peer, then list that too */
494 key = sensitive_data.host_certificates[i];
495 if (key == NULL)
496 continue;
497 switch (key->type) {
498 case KEY_RSA_CERT:
499 /* for RSA we also support SHA2 signatures */
500 append_hostkey_type(b,
501 "rsa-sha2-512-cert-v01@openssh.com");
502 append_hostkey_type(b,
503 "rsa-sha2-256-cert-v01@openssh.com");
504 /* FALLTHROUGH */
505 case KEY_DSA_CERT:
506 case KEY_ECDSA_CERT:
507 case KEY_ED25519_CERT:
508 case KEY_ECDSA_SK_CERT:
509 case KEY_ED25519_SK_CERT:
510 case KEY_XMSS_CERT:
511 append_hostkey_type(b, sshkey_ssh_name(key));
512 break;
513 }
514 }
515 if ((ret = sshbuf_dup_string(b)) == NULL)
516 fatal_f("sshbuf_dup_string failed");
517 sshbuf_free(b);
518 debug_f("%s", ret);
519 return ret;
520 }
521
522 static struct sshkey *
get_hostkey_by_type(int type,int nid,int need_private,struct ssh * ssh)523 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh)
524 {
525 u_int i;
526 struct sshkey *key;
527
528 for (i = 0; i < options.num_host_key_files; i++) {
529 switch (type) {
530 case KEY_RSA_CERT:
531 case KEY_DSA_CERT:
532 case KEY_ECDSA_CERT:
533 case KEY_ED25519_CERT:
534 case KEY_ECDSA_SK_CERT:
535 case KEY_ED25519_SK_CERT:
536 case KEY_XMSS_CERT:
537 key = sensitive_data.host_certificates[i];
538 break;
539 default:
540 key = sensitive_data.host_keys[i];
541 if (key == NULL && !need_private)
542 key = sensitive_data.host_pubkeys[i];
543 break;
544 }
545 if (key == NULL || key->type != type)
546 continue;
547 switch (type) {
548 case KEY_ECDSA:
549 case KEY_ECDSA_SK:
550 case KEY_ECDSA_CERT:
551 case KEY_ECDSA_SK_CERT:
552 if (key->ecdsa_nid != nid)
553 continue;
554 /* FALLTHROUGH */
555 default:
556 return need_private ?
557 sensitive_data.host_keys[i] : key;
558 }
559 }
560 return NULL;
561 }
562
563 struct sshkey *
get_hostkey_public_by_type(int type,int nid,struct ssh * ssh)564 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh)
565 {
566 return get_hostkey_by_type(type, nid, 0, ssh);
567 }
568
569 struct sshkey *
get_hostkey_private_by_type(int type,int nid,struct ssh * ssh)570 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh)
571 {
572 return get_hostkey_by_type(type, nid, 1, ssh);
573 }
574
575 struct sshkey *
get_hostkey_by_index(int ind)576 get_hostkey_by_index(int ind)
577 {
578 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
579 return (NULL);
580 return (sensitive_data.host_keys[ind]);
581 }
582
583 struct sshkey *
get_hostkey_public_by_index(int ind,struct ssh * ssh)584 get_hostkey_public_by_index(int ind, struct ssh *ssh)
585 {
586 if (ind < 0 || (u_int)ind >= options.num_host_key_files)
587 return (NULL);
588 return (sensitive_data.host_pubkeys[ind]);
589 }
590
591 int
get_hostkey_index(struct sshkey * key,int compare,struct ssh * ssh)592 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh)
593 {
594 u_int i;
595
596 for (i = 0; i < options.num_host_key_files; i++) {
597 if (sshkey_is_cert(key)) {
598 if (key == sensitive_data.host_certificates[i] ||
599 (compare && sensitive_data.host_certificates[i] &&
600 sshkey_equal(key,
601 sensitive_data.host_certificates[i])))
602 return (i);
603 } else {
604 if (key == sensitive_data.host_keys[i] ||
605 (compare && sensitive_data.host_keys[i] &&
606 sshkey_equal(key, sensitive_data.host_keys[i])))
607 return (i);
608 if (key == sensitive_data.host_pubkeys[i] ||
609 (compare && sensitive_data.host_pubkeys[i] &&
610 sshkey_equal(key, sensitive_data.host_pubkeys[i])))
611 return (i);
612 }
613 }
614 return (-1);
615 }
616
617 /* Inform the client of all hostkeys */
618 static void
notify_hostkeys(struct ssh * ssh)619 notify_hostkeys(struct ssh *ssh)
620 {
621 struct sshbuf *buf;
622 struct sshkey *key;
623 u_int i, nkeys;
624 int r;
625 char *fp;
626
627 /* Some clients cannot cope with the hostkeys message, skip those. */
628 if (ssh->compat & SSH_BUG_HOSTKEYS)
629 return;
630
631 if ((buf = sshbuf_new()) == NULL)
632 fatal_f("sshbuf_new");
633 for (i = nkeys = 0; i < options.num_host_key_files; i++) {
634 key = get_hostkey_public_by_index(i, ssh);
635 if (key == NULL || key->type == KEY_UNSPEC ||
636 sshkey_is_cert(key))
637 continue;
638 fp = sshkey_fingerprint(key, options.fingerprint_hash,
639 SSH_FP_DEFAULT);
640 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp);
641 free(fp);
642 if (nkeys == 0) {
643 /*
644 * Start building the request when we find the
645 * first usable key.
646 */
647 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
648 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 ||
649 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */
650 sshpkt_fatal(ssh, r, "%s: start request", __func__);
651 }
652 /* Append the key to the request */
653 sshbuf_reset(buf);
654 if ((r = sshkey_putb(key, buf)) != 0)
655 fatal_fr(r, "couldn't put hostkey %d", i);
656 if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
657 sshpkt_fatal(ssh, r, "%s: append key", __func__);
658 nkeys++;
659 }
660 debug3_f("sent %u hostkeys", nkeys);
661 if (nkeys == 0)
662 fatal_f("no hostkeys");
663 if ((r = sshpkt_send(ssh)) != 0)
664 sshpkt_fatal(ssh, r, "%s: send", __func__);
665 sshbuf_free(buf);
666 }
667
668 static void
usage(void)669 usage(void)
670 {
671 fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION);
672 fprintf(stderr,
673 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n"
674 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
675 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
676 );
677 exit(1);
678 }
679
680 static void
parse_hostkeys(struct sshbuf * hostkeys)681 parse_hostkeys(struct sshbuf *hostkeys)
682 {
683 int r;
684 u_int num_keys = 0;
685 struct sshkey *k;
686 struct sshbuf *kbuf;
687 const u_char *cp;
688 size_t len;
689
690 while (sshbuf_len(hostkeys) != 0) {
691 if (num_keys > 2048)
692 fatal_f("too many hostkeys");
693 sensitive_data.host_keys = xrecallocarray(
694 sensitive_data.host_keys, num_keys, num_keys + 1,
695 sizeof(*sensitive_data.host_pubkeys));
696 sensitive_data.host_pubkeys = xrecallocarray(
697 sensitive_data.host_pubkeys, num_keys, num_keys + 1,
698 sizeof(*sensitive_data.host_pubkeys));
699 sensitive_data.host_certificates = xrecallocarray(
700 sensitive_data.host_certificates, num_keys, num_keys + 1,
701 sizeof(*sensitive_data.host_certificates));
702 /* private key */
703 k = NULL;
704 if ((r = sshbuf_froms(hostkeys, &kbuf)) != 0)
705 fatal_fr(r, "extract privkey");
706 if (sshbuf_len(kbuf) != 0 &&
707 (r = sshkey_private_deserialize(kbuf, &k)) != 0)
708 fatal_fr(r, "parse pubkey");
709 sensitive_data.host_keys[num_keys] = k;
710 sshbuf_free(kbuf);
711 if (k)
712 debug2_f("privkey %u: %s", num_keys, sshkey_ssh_name(k));
713 /* public key */
714 k = NULL;
715 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
716 fatal_fr(r, "extract pubkey");
717 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
718 fatal_fr(r, "parse pubkey");
719 sensitive_data.host_pubkeys[num_keys] = k;
720 if (k)
721 debug2_f("pubkey %u: %s", num_keys, sshkey_ssh_name(k));
722 /* certificate */
723 k = NULL;
724 if ((r = sshbuf_get_string_direct(hostkeys, &cp, &len)) != 0)
725 fatal_fr(r, "extract pubkey");
726 if (len != 0 && (r = sshkey_from_blob(cp, len, &k)) != 0)
727 fatal_fr(r, "parse pubkey");
728 sensitive_data.host_certificates[num_keys] = k;
729 if (k)
730 debug2_f("cert %u: %s", num_keys, sshkey_ssh_name(k));
731 num_keys++;
732 }
733 sensitive_data.num_hostkeys = num_keys;
734 }
735
736 static void
recv_rexec_state(int fd,struct sshbuf * conf,uint64_t * timing_secretp)737 recv_rexec_state(int fd, struct sshbuf *conf, uint64_t *timing_secretp)
738 {
739 struct sshbuf *m, *inc, *hostkeys;
740 u_char *cp, ver;
741 size_t len;
742 int r;
743 struct include_item *item;
744
745 debug3_f("entering fd = %d", fd);
746
747 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL)
748 fatal_f("sshbuf_new failed");
749 if (ssh_msg_recv(fd, m) == -1)
750 fatal_f("ssh_msg_recv failed");
751 if ((r = sshbuf_get_u8(m, &ver)) != 0)
752 fatal_fr(r, "parse version");
753 if (ver != 0)
754 fatal_f("rexec version mismatch");
755 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || /* XXX _direct */
756 (r = sshbuf_get_u64(m, timing_secretp)) != 0 ||
757 (r = sshbuf_froms(m, &hostkeys)) != 0 ||
758 (r = sshbuf_get_stringb(m, inc)) != 0)
759 fatal_fr(r, "parse config");
760
761 if (conf != NULL && (r = sshbuf_put(conf, cp, len)))
762 fatal_fr(r, "sshbuf_put");
763
764 while (sshbuf_len(inc) != 0) {
765 item = xcalloc(1, sizeof(*item));
766 if ((item->contents = sshbuf_new()) == NULL)
767 fatal_f("sshbuf_new failed");
768 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 ||
769 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 ||
770 (r = sshbuf_get_stringb(inc, item->contents)) != 0)
771 fatal_fr(r, "parse includes");
772 TAILQ_INSERT_TAIL(&includes, item, entry);
773 }
774
775 parse_hostkeys(hostkeys);
776
777 free(cp);
778 sshbuf_free(m);
779 sshbuf_free(hostkeys);
780 sshbuf_free(inc);
781
782 debug3_f("done");
783 }
784
785 /*
786 * If IP options are supported, make sure there are none (log and
787 * return an error if any are found). Basically we are worried about
788 * source routing; it can be used to pretend you are somebody
789 * (ip-address) you are not. That itself may be "almost acceptable"
790 * under certain circumstances, but rhosts authentication is useless
791 * if source routing is accepted. Notice also that if we just dropped
792 * source routing here, the other side could use IP spoofing to do
793 * rest of the interaction and could still bypass security. So we
794 * exit here if we detect any IP options.
795 */
796 static void
check_ip_options(struct ssh * ssh)797 check_ip_options(struct ssh *ssh)
798 {
799 #ifdef IP_OPTIONS
800 int sock_in = ssh_packet_get_connection_in(ssh);
801 struct sockaddr_storage from;
802 u_char opts[200];
803 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from);
804 char text[sizeof(opts) * 3 + 1];
805
806 memset(&from, 0, sizeof(from));
807 if (getpeername(sock_in, (struct sockaddr *)&from,
808 &fromlen) == -1)
809 return;
810 if (from.ss_family != AF_INET)
811 return;
812 /* XXX IPv6 options? */
813
814 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts,
815 &option_size) >= 0 && option_size != 0) {
816 text[0] = '\0';
817 for (i = 0; i < option_size; i++)
818 snprintf(text + i*3, sizeof(text) - i*3,
819 " %2.2x", opts[i]);
820 fatal("Connection from %.100s port %d with IP opts: %.800s",
821 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text);
822 }
823 #endif /* IP_OPTIONS */
824 }
825
826 /* Set the routing domain for this process */
827 static void
set_process_rdomain(struct ssh * ssh,const char * name)828 set_process_rdomain(struct ssh *ssh, const char *name)
829 {
830 #if defined(HAVE_SYS_SET_PROCESS_RDOMAIN)
831 if (name == NULL)
832 return; /* default */
833
834 if (strcmp(name, "%D") == 0) {
835 /* "expands" to routing domain of connection */
836 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
837 return;
838 }
839 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */
840 return sys_set_process_rdomain(name);
841 #elif defined(__OpenBSD__)
842 int rtable, ortable = getrtable();
843 const char *errstr;
844
845 if (name == NULL)
846 return; /* default */
847
848 if (strcmp(name, "%D") == 0) {
849 /* "expands" to routing domain of connection */
850 if ((name = ssh_packet_rdomain_in(ssh)) == NULL)
851 return;
852 }
853
854 rtable = (int)strtonum(name, 0, 255, &errstr);
855 if (errstr != NULL) /* Shouldn't happen */
856 fatal("Invalid routing domain \"%s\": %s", name, errstr);
857 if (rtable != ortable && setrtable(rtable) != 0)
858 fatal("Unable to set routing domain %d: %s",
859 rtable, strerror(errno));
860 debug_f("set routing domain %d (was %d)", rtable, ortable);
861 #else /* defined(__OpenBSD__) */
862 fatal("Unable to set routing domain: not supported in this platform");
863 #endif
864 }
865
866 /*
867 * Main program for the daemon.
868 */
869 int
main(int ac,char ** av)870 main(int ac, char **av)
871 {
872 struct ssh *ssh = NULL;
873 extern char *optarg;
874 extern int optind;
875 int r, opt, on = 1, remote_port;
876 int sock_in = -1, sock_out = -1, rexeced_flag = 0, have_key = 0;
877 const char *remote_ip, *rdomain;
878 char *line, *laddr, *logfile = NULL;
879 u_int i;
880 u_int64_t ibytes, obytes;
881 mode_t new_umask;
882 Authctxt *authctxt;
883 struct connection_info *connection_info = NULL;
884 sigset_t sigmask;
885 uint64_t timing_secret = 0;
886 struct itimerval itv;
887
888 sigemptyset(&sigmask);
889 sigprocmask(SIG_SETMASK, &sigmask, NULL);
890
891 #ifdef HAVE_SECUREWARE
892 (void)set_auth_parameters(ac, av);
893 #endif
894 __progname = ssh_get_progname(av[0]);
895
896 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
897 saved_argc = ac;
898 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
899 for (i = 0; (int)i < ac; i++)
900 saved_argv[i] = xstrdup(av[i]);
901 saved_argv[i] = NULL;
902
903 #ifndef HAVE_SETPROCTITLE
904 /* Prepare for later setproctitle emulation */
905 compat_init_setproctitle(ac, av);
906 av = saved_argv;
907 #endif
908
909 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
910 sanitise_stdfd();
911
912 /* Initialize configuration options to their default values. */
913 initialize_server_options(&options);
914
915 /* Parse command-line arguments. */
916 while ((opt = getopt(ac, av,
917 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) {
918 switch (opt) {
919 case '4':
920 options.address_family = AF_INET;
921 break;
922 case '6':
923 options.address_family = AF_INET6;
924 break;
925 case 'f':
926 config_file_name = optarg;
927 break;
928 case 'c':
929 servconf_add_hostcert("[command-line]", 0,
930 &options, optarg);
931 break;
932 case 'd':
933 if (debug_flag == 0) {
934 debug_flag = 1;
935 options.log_level = SYSLOG_LEVEL_DEBUG1;
936 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
937 options.log_level++;
938 break;
939 case 'D':
940 /* ignore */
941 break;
942 case 'E':
943 logfile = optarg;
944 /* FALLTHROUGH */
945 case 'e':
946 log_stderr = 1;
947 break;
948 case 'i':
949 inetd_flag = 1;
950 break;
951 case 'r':
952 /* ignore */
953 break;
954 case 'R':
955 rexeced_flag = 1;
956 break;
957 case 'Q':
958 /* ignored */
959 break;
960 case 'q':
961 options.log_level = SYSLOG_LEVEL_QUIET;
962 break;
963 case 'b':
964 /* protocol 1, ignored */
965 break;
966 case 'p':
967 options.ports_from_cmdline = 1;
968 if (options.num_ports >= MAX_PORTS) {
969 fprintf(stderr, "too many ports.\n");
970 exit(1);
971 }
972 options.ports[options.num_ports++] = a2port(optarg);
973 if (options.ports[options.num_ports-1] <= 0) {
974 fprintf(stderr, "Bad port number.\n");
975 exit(1);
976 }
977 break;
978 case 'g':
979 if ((options.login_grace_time = convtime(optarg)) == -1) {
980 fprintf(stderr, "Invalid login grace time.\n");
981 exit(1);
982 }
983 break;
984 case 'k':
985 /* protocol 1, ignored */
986 break;
987 case 'h':
988 servconf_add_hostkey("[command-line]", 0,
989 &options, optarg, 1);
990 break;
991 case 't':
992 case 'T':
993 case 'G':
994 fatal("test/dump modes not supported");
995 break;
996 case 'C':
997 connection_info = server_get_connection_info(ssh, 0, 0);
998 if (parse_server_match_testspec(connection_info,
999 optarg) == -1)
1000 exit(1);
1001 break;
1002 case 'u':
1003 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1004 if (utmp_len > HOST_NAME_MAX+1) {
1005 fprintf(stderr, "Invalid utmp length.\n");
1006 exit(1);
1007 }
1008 break;
1009 case 'o':
1010 line = xstrdup(optarg);
1011 if (process_server_config_line(&options, line,
1012 "command-line", 0, NULL, NULL, &includes) != 0)
1013 exit(1);
1014 free(line);
1015 break;
1016 case 'V':
1017 fprintf(stderr, "%s, %s\n",
1018 SSH_RELEASE, SSH_OPENSSL_VERSION);
1019 exit(0);
1020 default:
1021 usage();
1022 break;
1023 }
1024 }
1025
1026 /* Check that there are no remaining arguments. */
1027 if (optind < ac) {
1028 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1029 exit(1);
1030 }
1031
1032 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1033
1034 if (!rexeced_flag)
1035 fatal("sshd-session should not be executed directly");
1036
1037 closefrom(REEXEC_MIN_FREE_FD);
1038
1039 seed_rng();
1040
1041 /* If requested, redirect the logs to the specified logfile. */
1042 if (logfile != NULL) {
1043 char *cp, pid_s[32];
1044
1045 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
1046 cp = percent_expand(logfile,
1047 "p", pid_s,
1048 "P", "sshd-session",
1049 (char *)NULL);
1050 log_redirect_stderr_to(cp);
1051 free(cp);
1052 }
1053
1054 /*
1055 * Force logging to stderr until we have loaded the private host
1056 * key (unless started from inetd)
1057 */
1058 log_init(__progname,
1059 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1060 SYSLOG_LEVEL_INFO : options.log_level,
1061 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1062 SYSLOG_FACILITY_AUTH : options.log_facility,
1063 log_stderr || !inetd_flag || debug_flag);
1064
1065 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1066
1067 /* Fetch our configuration */
1068 if ((cfg = sshbuf_new()) == NULL)
1069 fatal("sshbuf_new config buf failed");
1070 setproctitle("%s", "[rexeced]");
1071 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg, &timing_secret);
1072 close(REEXEC_CONFIG_PASS_FD);
1073 parse_server_config(&options, "rexec", cfg, &includes, NULL, 1);
1074 /* Fill in default values for those options not explicitly set. */
1075 fill_default_server_options(&options);
1076 options.timing_secret = timing_secret;
1077
1078 /* Store privilege separation user for later use if required. */
1079 privsep_chroot = (getuid() == 0 || geteuid() == 0);
1080 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) {
1081 if (privsep_chroot || options.kerberos_authentication)
1082 fatal("Privilege separation user %s does not exist",
1083 SSH_PRIVSEP_USER);
1084 } else {
1085 privsep_pw = pwcopy(privsep_pw);
1086 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd));
1087 privsep_pw->pw_passwd = xstrdup("*");
1088 }
1089 endpwent();
1090
1091 if (!debug_flag) {
1092 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1093 close(REEXEC_STARTUP_PIPE_FD);
1094 /*
1095 * Signal parent that this child is at a point where
1096 * they can go away if they have a SIGHUP pending.
1097 */
1098 (void)atomicio(vwrite, startup_pipe, "\0", 1);
1099 }
1100
1101 /* Check that options are sensible */
1102 if (options.authorized_keys_command_user == NULL &&
1103 (options.authorized_keys_command != NULL &&
1104 strcasecmp(options.authorized_keys_command, "none") != 0))
1105 fatal("AuthorizedKeysCommand set without "
1106 "AuthorizedKeysCommandUser");
1107 if (options.authorized_principals_command_user == NULL &&
1108 (options.authorized_principals_command != NULL &&
1109 strcasecmp(options.authorized_principals_command, "none") != 0))
1110 fatal("AuthorizedPrincipalsCommand set without "
1111 "AuthorizedPrincipalsCommandUser");
1112
1113 /*
1114 * Check whether there is any path through configured auth methods.
1115 * Unfortunately it is not possible to verify this generally before
1116 * daemonisation in the presence of Match block, but this catches
1117 * and warns for trivial misconfigurations that could break login.
1118 */
1119 if (options.num_auth_methods != 0) {
1120 for (i = 0; i < options.num_auth_methods; i++) {
1121 if (auth2_methods_valid(options.auth_methods[i],
1122 1) == 0)
1123 break;
1124 }
1125 if (i >= options.num_auth_methods)
1126 fatal("AuthenticationMethods cannot be satisfied by "
1127 "enabled authentication methods");
1128 }
1129
1130 #ifdef WITH_OPENSSL
1131 if (options.moduli_file != NULL)
1132 dh_set_moduli_file(options.moduli_file);
1133 #endif
1134
1135 if (options.host_key_agent) {
1136 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1137 setenv(SSH_AUTHSOCKET_ENV_NAME,
1138 options.host_key_agent, 1);
1139 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1140 have_agent = 1;
1141 else
1142 error_r(r, "Could not connect to agent \"%s\"",
1143 options.host_key_agent);
1144 }
1145
1146 if (options.num_host_key_files != sensitive_data.num_hostkeys) {
1147 fatal("internal error: hostkeys confused (config %u recvd %u)",
1148 options.num_host_key_files, sensitive_data.num_hostkeys);
1149 }
1150
1151 for (i = 0; i < options.num_host_key_files; i++) {
1152 if (sensitive_data.host_keys[i] != NULL ||
1153 (have_agent && sensitive_data.host_pubkeys[i] != NULL)) {
1154 have_key = 1;
1155 break;
1156 }
1157 }
1158 if (!have_key)
1159 fatal("internal error: monitor received no hostkeys");
1160
1161 /* Ensure that umask disallows at least group and world write */
1162 new_umask = umask(0077) | 0022;
1163 (void) umask(new_umask);
1164
1165 /* Initialize the log (it is reinitialized below in case we forked). */
1166 if (debug_flag)
1167 log_stderr = 1;
1168 log_init(__progname, options.log_level,
1169 options.log_facility, log_stderr);
1170 for (i = 0; i < options.num_log_verbose; i++)
1171 log_verbose_add(options.log_verbose[i]);
1172
1173 /* Reinitialize the log (because of the fork above). */
1174 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1175
1176 /*
1177 * Chdir to the root directory so that the current disk can be
1178 * unmounted if desired.
1179 */
1180 if (chdir("/") == -1)
1181 error("chdir(\"/\"): %s", strerror(errno));
1182
1183 /* ignore SIGPIPE */
1184 ssh_signal(SIGPIPE, SIG_IGN);
1185
1186 /* Get a connection, either from inetd or rexec */
1187 if (inetd_flag) {
1188 /*
1189 * NB. must be different fd numbers for the !socket case,
1190 * as packet_connection_is_on_socket() depends on this.
1191 */
1192 sock_in = dup(STDIN_FILENO);
1193 sock_out = dup(STDOUT_FILENO);
1194 } else {
1195 /* rexec case; accept()ed socket in ancestor listener */
1196 sock_in = sock_out = dup(STDIN_FILENO);
1197 }
1198
1199 /*
1200 * We intentionally do not close the descriptors 0, 1, and 2
1201 * as our code for setting the descriptors won't work if
1202 * ttyfd happens to be one of those.
1203 */
1204 if (stdfd_devnull(1, 1, !log_stderr) == -1)
1205 error("stdfd_devnull failed");
1206 debug("network sockets: %d, %d", sock_in, sock_out);
1207
1208 /* This is the child processing a new connection. */
1209 setproctitle("%s", "[accepted]");
1210
1211 /* Executed child processes don't need these. */
1212 fcntl(sock_out, F_SETFD, FD_CLOEXEC);
1213 fcntl(sock_in, F_SETFD, FD_CLOEXEC);
1214
1215 /* We will not restart on SIGHUP since it no longer makes sense. */
1216 ssh_signal(SIGALRM, SIG_DFL);
1217 ssh_signal(SIGHUP, SIG_DFL);
1218 ssh_signal(SIGTERM, SIG_DFL);
1219 ssh_signal(SIGQUIT, SIG_DFL);
1220 ssh_signal(SIGCHLD, SIG_DFL);
1221 ssh_signal(SIGINT, SIG_DFL);
1222
1223 /*
1224 * Register our connection. This turns encryption off because we do
1225 * not have a key.
1226 */
1227 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL)
1228 fatal("Unable to create connection");
1229 the_active_state = ssh;
1230 ssh_packet_set_server(ssh);
1231
1232 check_ip_options(ssh);
1233
1234 /* Prepare the channels layer */
1235 channel_init_channels(ssh);
1236 channel_set_af(ssh, options.address_family);
1237 server_process_channel_timeouts(ssh);
1238 server_process_permitopen(ssh);
1239
1240 /* Set SO_KEEPALIVE if requested. */
1241 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) &&
1242 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1)
1243 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1244
1245 if ((remote_port = ssh_remote_port(ssh)) < 0) {
1246 debug("ssh_remote_port failed");
1247 cleanup_exit(255);
1248 }
1249
1250 #ifdef HAVE_LOGIN_CAP
1251 /* Also caches remote hostname for sandboxed child. */
1252 auth_get_canonical_hostname(ssh, options.use_dns);
1253 #endif
1254
1255 /*
1256 * The rest of the code depends on the fact that
1257 * ssh_remote_ipaddr() caches the remote ip, even if
1258 * the socket goes away.
1259 */
1260 remote_ip = ssh_remote_ipaddr(ssh);
1261
1262 #ifdef SSH_AUDIT_EVENTS
1263 audit_connection_from(remote_ip, remote_port);
1264 #endif
1265
1266 rdomain = ssh_packet_rdomain_in(ssh);
1267
1268 /* Log the connection. */
1269 laddr = get_local_ipaddr(sock_in);
1270 verbose("Connection from %s port %d on %s port %d%s%s%s",
1271 remote_ip, remote_port, laddr, ssh_local_port(ssh),
1272 rdomain == NULL ? "" : " rdomain \"",
1273 rdomain == NULL ? "" : rdomain,
1274 rdomain == NULL ? "" : "\"");
1275 free(laddr);
1276
1277 /*
1278 * We don't want to listen forever unless the other side
1279 * successfully authenticates itself. So we set up an alarm which is
1280 * cleared after successful authentication. A limit of zero
1281 * indicates no limit. Note that we don't set the alarm in debugging
1282 * mode; it is just annoying to have the server exit just when you
1283 * are about to discover the bug.
1284 */
1285 ssh_signal(SIGALRM, grace_alarm_handler);
1286 if (!debug_flag && options.login_grace_time > 0) {
1287 int ujitter = arc4random_uniform(4 * 1000000);
1288
1289 timerclear(&itv.it_interval);
1290 itv.it_value.tv_sec = options.login_grace_time;
1291 itv.it_value.tv_sec += ujitter / 1000000;
1292 itv.it_value.tv_usec = ujitter % 1000000;
1293
1294 if (setitimer(ITIMER_REAL, &itv, NULL) == -1)
1295 fatal("login grace time setitimer failed");
1296 }
1297
1298 if ((r = kex_exchange_identification(ssh, -1,
1299 options.version_addendum)) != 0)
1300 sshpkt_fatal(ssh, r, "banner exchange");
1301
1302 ssh_packet_set_nonblocking(ssh);
1303
1304 /* allocate authentication context */
1305 authctxt = xcalloc(1, sizeof(*authctxt));
1306 ssh->authctxt = authctxt;
1307
1308 /* XXX global for cleanup, access from other modules */
1309 the_authctxt = authctxt;
1310
1311 /* Set default key authentication options */
1312 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL)
1313 fatal("allocation failed");
1314
1315 /* prepare buffer to collect messages to display to user after login */
1316 if ((loginmsg = sshbuf_new()) == NULL)
1317 fatal("sshbuf_new loginmsg failed");
1318 auth_debug_reset();
1319
1320 BLACKLIST_INIT();
1321
1322 if (privsep_preauth(ssh) == 1)
1323 goto authenticated;
1324
1325 /* perform the key exchange */
1326 /* authenticate user and start session */
1327 do_ssh2_kex(ssh);
1328 do_authentication2(ssh);
1329
1330 /*
1331 * The unprivileged child now transfers the current keystate and exits.
1332 */
1333 mm_send_keystate(ssh, pmonitor);
1334 ssh_packet_clear_keys(ssh);
1335 exit(0);
1336
1337 authenticated:
1338 /*
1339 * Cancel the alarm we set to limit the time taken for
1340 * authentication.
1341 */
1342 timerclear(&itv.it_interval);
1343 timerclear(&itv.it_value);
1344 if (setitimer(ITIMER_REAL, &itv, NULL) == -1)
1345 fatal("login grace time clear failed");
1346 ssh_signal(SIGALRM, SIG_DFL);
1347 authctxt->authenticated = 1;
1348 if (startup_pipe != -1) {
1349 /* signal listener that authentication completed successfully */
1350 (void)atomicio(vwrite, startup_pipe, "\001", 1);
1351 close(startup_pipe);
1352 startup_pipe = -1;
1353 }
1354
1355 if (options.routing_domain != NULL)
1356 set_process_rdomain(ssh, options.routing_domain);
1357
1358 #ifdef SSH_AUDIT_EVENTS
1359 audit_event(ssh, SSH_AUTH_SUCCESS);
1360 #endif
1361
1362 #ifdef GSSAPI
1363 if (options.gss_authentication) {
1364 temporarily_use_uid(authctxt->pw);
1365 ssh_gssapi_storecreds();
1366 restore_uid();
1367 }
1368 #endif
1369 #ifdef USE_PAM
1370 if (options.use_pam) {
1371 do_pam_setcred();
1372 do_pam_session(ssh);
1373 }
1374 #endif
1375
1376 /*
1377 * In privilege separation, we fork another child and prepare
1378 * file descriptor passing.
1379 */
1380 privsep_postauth(ssh, authctxt);
1381 /* the monitor process [priv] will not return */
1382
1383 ssh_packet_set_timeout(ssh, options.client_alive_interval,
1384 options.client_alive_count_max);
1385
1386 /* Try to send all our hostkeys to the client */
1387 notify_hostkeys(ssh);
1388
1389 /* Start session. */
1390 do_authenticated(ssh, authctxt);
1391
1392 /* The connection has been terminated. */
1393 ssh_packet_get_bytes(ssh, &ibytes, &obytes);
1394 verbose("Transferred: sent %llu, received %llu bytes",
1395 (unsigned long long)obytes, (unsigned long long)ibytes);
1396
1397 verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1398
1399 #ifdef USE_PAM
1400 if (options.use_pam)
1401 finish_pam();
1402 #endif /* USE_PAM */
1403
1404 #ifdef SSH_AUDIT_EVENTS
1405 mm_audit_event(ssh, SSH_CONNECTION_CLOSE);
1406 #endif
1407
1408 ssh_packet_close(ssh);
1409
1410 mm_terminate();
1411
1412 exit(0);
1413 }
1414
1415 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)1416 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey,
1417 struct sshkey *pubkey, u_char **signature, size_t *slenp,
1418 const u_char *data, size_t dlen, const char *alg)
1419 {
1420 if (privkey) {
1421 if (mm_sshkey_sign(ssh, privkey, signature, slenp,
1422 data, dlen, alg, options.sk_provider, NULL,
1423 ssh->compat) < 0)
1424 fatal_f("privkey sign failed");
1425 } else {
1426 if (mm_sshkey_sign(ssh, pubkey, signature, slenp,
1427 data, dlen, alg, options.sk_provider, NULL,
1428 ssh->compat) < 0)
1429 fatal_f("pubkey sign failed");
1430 }
1431 return 0;
1432 }
1433
1434 /* SSH2 key exchange */
1435 static void
do_ssh2_kex(struct ssh * ssh)1436 do_ssh2_kex(struct ssh *ssh)
1437 {
1438 char *hkalgs = NULL, *myproposal[PROPOSAL_MAX];
1439 const char *compression = NULL;
1440 struct kex *kex;
1441 int r;
1442
1443 if (options.rekey_limit || options.rekey_interval)
1444 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
1445 options.rekey_interval);
1446
1447 if (options.compression == COMP_NONE)
1448 compression = "none";
1449 hkalgs = list_hostkey_types();
1450
1451 kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms,
1452 options.ciphers, options.macs, compression, hkalgs);
1453
1454 free(hkalgs);
1455
1456 /* start key exchange */
1457 if ((r = kex_setup(ssh, myproposal)) != 0)
1458 fatal_r(r, "kex_setup");
1459 kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos);
1460 kex = ssh->kex;
1461
1462 #ifdef WITH_OPENSSL
1463 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1464 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1465 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1466 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1467 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1468 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1469 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1470 #ifdef OPENSSL_HAS_ECC
1471 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1472 #endif
1473 #endif
1474 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1475 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1476 kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server;
1477 kex->load_host_public_key=&get_hostkey_public_by_type;
1478 kex->load_host_private_key=&get_hostkey_private_by_type;
1479 kex->host_key_index=&get_hostkey_index;
1480 kex->sign = sshd_hostkey_sign;
1481
1482 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done);
1483 kex_proposal_free_entries(myproposal);
1484
1485 #ifdef DEBUG_KEXDH
1486 /* send 1st encrypted/maced/compressed message */
1487 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
1488 (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
1489 (r = sshpkt_send(ssh)) != 0 ||
1490 (r = ssh_packet_write_wait(ssh)) != 0)
1491 fatal_fr(r, "send test");
1492 #endif
1493 debug("KEX done");
1494 }
1495
1496 /* server specific fatal cleanup */
1497 void
cleanup_exit(int i)1498 cleanup_exit(int i)
1499 {
1500 extern int auth_attempted; /* monitor.c */
1501
1502 if (the_active_state != NULL && the_authctxt != NULL) {
1503 do_cleanup(the_active_state, the_authctxt);
1504 if (privsep_is_preauth &&
1505 pmonitor != NULL && pmonitor->m_pid > 1) {
1506 debug("Killing privsep child %d", pmonitor->m_pid);
1507 if (kill(pmonitor->m_pid, SIGKILL) != 0 &&
1508 errno != ESRCH) {
1509 error_f("kill(%d): %s", pmonitor->m_pid,
1510 strerror(errno));
1511 }
1512 }
1513 }
1514 #ifdef SSH_AUDIT_EVENTS
1515 /* done after do_cleanup so it can cancel the PAM auth 'thread' */
1516 if (the_active_state != NULL && mm_is_monitor())
1517 audit_event(the_active_state, SSH_CONNECTION_ABANDON);
1518 #endif
1519 /* Override default fatal exit value when auth was attempted */
1520 if (i == 255 && auth_attempted)
1521 _exit(EXIT_AUTH_ATTEMPTED);
1522 _exit(i);
1523 }
1524