1 /* $NetBSD: sshd.c,v 1.55 2025/04/09 15:49:33 christos Exp $ */
2 /* $OpenBSD: sshd.c,v 1.617 2025/04/07 08:12:22 dtucker Exp $ */
3
4 /*
5 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
6 * Copyright (c) 2002 Niels Provos. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include "includes.h"
30 __RCSID("$NetBSD: sshd.c,v 1.55 2025/04/09 15:49:33 christos Exp $");
31 #include <sys/types.h>
32 #include <sys/param.h>
33 #include <sys/ioctl.h>
34 #include <sys/wait.h>
35 #include <sys/tree.h>
36 #include <sys/stat.h>
37 #include <sys/socket.h>
38 #include <sys/time.h>
39 #include <sys/queue.h>
40 #include <sys/utsname.h>
41
42 #include <errno.h>
43 #include <fcntl.h>
44 #include <netdb.h>
45 #include <paths.h>
46 #include <poll.h>
47 #include <pwd.h>
48 #include <signal.h>
49 #include <stdio.h>
50 #include <stdlib.h>
51 #include <string.h>
52 #include <stdarg.h>
53 #include <time.h>
54 #include <unistd.h>
55 #include <limits.h>
56
57 #ifdef WITH_OPENSSL
58 #include <openssl/bn.h>
59 #include <openssl/evp.h>
60 #endif
61
62 #include "xmalloc.h"
63 #include "ssh.h"
64 #include "sshpty.h"
65 #include "log.h"
66 #include "sshbuf.h"
67 #include "misc.h"
68 #include "servconf.h"
69 #include "compat.h"
70 #include "digest.h"
71 #include "sshkey.h"
72 #include "authfile.h"
73 #include "pathnames.h"
74 #include "canohost.h"
75 #include "hostfile.h"
76 #include "auth.h"
77 #include "authfd.h"
78 #include "misc.h"
79 #include "msg.h"
80 #include "version.h"
81 #include "ssherr.h"
82 #include "sk-api.h"
83 #include "addr.h"
84 #include "srclimit.h"
85 #include "atomicio.h"
86
87 #ifdef LIBWRAP
88 #include <tcpd.h>
89 #include <syslog.h>
90 int allow_severity = LOG_INFO;
91 int deny_severity = LOG_WARNING;
92 #endif /* LIBWRAP */
93
94 #ifdef WITH_LDAP_PUBKEY
95 #include "ldapauth.h"
96 #endif
97
98 #ifndef HOST_NAME_MAX
99 #define HOST_NAME_MAX MAXHOSTNAMELEN
100 #endif
101
102 /* Re-exec fds */
103 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
104 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 2)
105 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 3)
106
107 extern char *__progname;
108
109 /* Server configuration options. */
110 ServerOptions options;
111
112 /*
113 * Debug mode flag. This can be set on the command line. If debug
114 * mode is enabled, extra debugging output will be sent to the system
115 * log, the daemon will not go to background, and will exit after processing
116 * the first connection.
117 */
118 int debug_flag = 0;
119
120 /* Saved arguments to main(). */
121 static char **saved_argv;
122
123 /*
124 * The sockets that the server is listening; this is used in the SIGHUP
125 * signal handler.
126 */
127 #define MAX_LISTEN_SOCKS 16
128 static int listen_socks[MAX_LISTEN_SOCKS];
129 static int num_listen_socks = 0;
130
131 /*
132 * Any really sensitive data in the application is contained in this
133 * structure. The idea is that this structure could be locked into memory so
134 * that the pages do not get written into swap. However, there are some
135 * problems. The private key contains BIGNUMs, and we do not (in principle)
136 * have access to the internals of them, and locking just the structure is
137 * not very useful. Currently, memory locking is not implemented.
138 */
139 struct {
140 struct sshkey **host_keys; /* all private host keys */
141 struct sshkey **host_pubkeys; /* all public host keys */
142 struct sshkey **host_certificates; /* all public host certificates */
143 int have_ssh2_key;
144 } sensitive_data;
145
146 /* This is set to true when a signal is received. */
147 static volatile sig_atomic_t received_siginfo = 0;
148 static volatile sig_atomic_t received_sigchld = 0;
149 static volatile sig_atomic_t received_sighup = 0;
150 static volatile sig_atomic_t received_sigterm = 0;
151
152 /* record remote hostname or ip */
153 u_int utmp_len = HOST_NAME_MAX+1;
154
155 /*
156 * The early_child/children array below is used for tracking children of the
157 * listening sshd process early in their lifespans, before they have
158 * completed authentication. This tracking is needed for four things:
159 *
160 * 1) Implementing the MaxStartups limit of concurrent unauthenticated
161 * connections.
162 * 2) Avoiding a race condition for SIGHUP processing, where child processes
163 * may have listen_socks open that could collide with main listener process
164 * after it restarts.
165 * 3) Ensuring that rexec'd sshd processes have received their initial state
166 * from the parent listen process before handling SIGHUP.
167 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor,
168 * including and especially those for LoginGraceTime timeouts.
169 *
170 * Child processes signal that they have completed closure of the listen_socks
171 * and (if applicable) received their rexec state by sending a char over their
172 * sock.
173 *
174 * Child processes signal that authentication has completed by sending a
175 * second char over the socket before closing it, otherwise the listener will
176 * continue tracking the child (and using up a MaxStartups slot) until the
177 * preauth subprocess exits, whereupon the listener will log its exit status.
178 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate
179 * they did not authenticate before the LoginGraceTime alarm fired.
180 */
181 struct early_child {
182 int pipefd;
183 int early; /* Indicates child closed listener */
184 char *id; /* human readable connection identifier */
185 pid_t pid;
186 struct xaddr addr;
187 int have_addr;
188 int status, have_status;
189 struct sshbuf *config;
190 struct sshbuf *keys;
191 };
192 static struct early_child *children;
193 static int children_active;
194
195 /* sshd_config buffer */
196 struct sshbuf *cfg;
197 struct sshbuf *config; /* packed */
198
199 /* Included files from the configuration file */
200 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
201
202 /* message to be displayed after login */
203 struct sshbuf *loginmsg;
204
205 static char *listener_proctitle;
206
207 /*
208 * Close all listening sockets
209 */
210 static void
close_listen_socks(void)211 close_listen_socks(void)
212 {
213 int i;
214
215 for (i = 0; i < num_listen_socks; i++)
216 close(listen_socks[i]);
217 num_listen_socks = 0;
218 }
219
220 /* Allocate and initialise the children array */
221 static void
child_alloc(void)222 child_alloc(void)
223 {
224 int i;
225
226 children = xcalloc(options.max_startups, sizeof(*children));
227 for (i = 0; i < options.max_startups; i++) {
228 children[i].pipefd = -1;
229 children[i].pid = -1;
230 }
231 }
232
233 /* Register a new connection in the children array; child pid comes later */
234 static struct early_child *
child_register(int pipefd,int sockfd)235 child_register(int pipefd, int sockfd)
236 {
237 int i, lport, rport;
238 char *laddr = NULL, *raddr = NULL;
239 struct early_child *child = NULL;
240 struct sockaddr_storage addr;
241 socklen_t addrlen = sizeof(addr);
242 struct sockaddr *sa = (struct sockaddr *)&addr;
243
244 for (i = 0; i < options.max_startups; i++) {
245 if (children[i].pipefd != -1 ||
246 children[i].config != NULL ||
247 children[i].keys != NULL ||
248 children[i].pid > 0)
249 continue;
250 child = &(children[i]);
251 break;
252 }
253 if (child == NULL) {
254 fatal_f("error: accepted connection when all %d child "
255 " slots full", options.max_startups);
256 }
257 child->pipefd = pipefd;
258 child->early = 1;
259 if ((child->config = sshbuf_fromb(config)) == NULL)
260 fatal_f("sshbuf_fromb failed");
261 /* record peer address, if available */
262 if (getpeername(sockfd, sa, &addrlen) == 0 &&
263 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0)
264 child->have_addr = 1;
265 /* format peer address string for logs */
266 if ((lport = get_local_port(sockfd)) == 0 ||
267 (rport = get_peer_port(sockfd)) == 0) {
268 /* Not a TCP socket */
269 raddr = get_peer_ipaddr(sockfd);
270 xasprintf(&child->id, "connection from %s", raddr);
271 } else {
272 laddr = get_local_ipaddr(sockfd);
273 raddr = get_peer_ipaddr(sockfd);
274 xasprintf(&child->id, "connection from %s to %s", raddr, laddr);
275 }
276 free(laddr);
277 free(raddr);
278 if (++children_active > options.max_startups)
279 fatal_f("internal error: more children than max_startups");
280
281 return child;
282 }
283
284 /*
285 * Finally free a child entry. Don't call this directly.
286 */
287 static void
child_finish(struct early_child * child)288 child_finish(struct early_child *child)
289 {
290 if (children_active == 0)
291 fatal_f("internal error: children_active underflow");
292 if (child->pipefd != -1)
293 close(child->pipefd);
294 sshbuf_free(child->config);
295 sshbuf_free(child->keys);
296 free(child->id);
297 memset(child, '\0', sizeof(*child));
298 child->pipefd = -1;
299 child->pid = -1;
300 children_active--;
301 }
302
303 /*
304 * Close a child's pipe. This will not stop tracking the child immediately
305 * (it will still be tracked for waitpid()) unless force_final is set, or
306 * child has already exited.
307 */
308 static void
child_close(struct early_child * child,int force_final,int quiet)309 child_close(struct early_child *child, int force_final, int quiet)
310 {
311 if (!quiet)
312 debug_f("enter%s", force_final ? " (forcing)" : "");
313 if (child->pipefd != -1) {
314 close(child->pipefd);
315 child->pipefd = -1;
316 }
317 if (child->pid == -1 || force_final)
318 child_finish(child);
319 }
320
321 /* Record a child exit. Safe to call from signal handlers */
322 static void
child_exit(pid_t pid,int status)323 child_exit(pid_t pid, int status)
324 {
325 int i;
326
327 if (children == NULL || pid <= 0)
328 return;
329 for (i = 0; i < options.max_startups; i++) {
330 if (children[i].pid == pid) {
331 children[i].have_status = 1;
332 children[i].status = status;
333 break;
334 }
335 }
336 }
337
338 /*
339 * Reap a child entry that has exited, as previously flagged
340 * using child_exit().
341 * Handles logging of exit condition and will finalise the child if its pipe
342 * had already been closed.
343 */
344 static void
child_reap(struct early_child * child)345 child_reap(struct early_child *child)
346 {
347 LogLevel level = SYSLOG_LEVEL_DEBUG1;
348 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE;
349 const char *child_status;
350
351 if (child->config)
352 child_status = " (sending config)";
353 else if (child->keys)
354 child_status = " (sending keys)";
355 else if (child->early)
356 child_status = " (early)";
357 else
358 child_status = "";
359
360 /* Log exit information */
361 if (WIFSIGNALED(child->status)) {
362 /*
363 * Increase logging for signals potentially associated
364 * with serious conditions.
365 */
366 if ((was_crash = signal_is_crash(WTERMSIG(child->status))))
367 level = SYSLOG_LEVEL_ERROR;
368 do_log2(level, "session process %ld for %s killed by "
369 "signal %d%s", (long)child->pid, child->id,
370 WTERMSIG(child->status), child_status);
371 if (was_crash)
372 penalty_type = SRCLIMIT_PENALTY_CRASH;
373 } else if (!WIFEXITED(child->status)) {
374 penalty_type = SRCLIMIT_PENALTY_CRASH;
375 error("session process %ld for %s terminated abnormally, "
376 "status=0x%x%s", (long)child->pid, child->id, child->status,
377 child_status);
378 } else {
379 /* Normal exit. We care about the status */
380 switch (WEXITSTATUS(child->status)) {
381 case 0:
382 debug3_f("preauth child %ld for %s completed "
383 "normally%s", (long)child->pid, child->id,
384 child_status);
385 break;
386 case EXIT_LOGIN_GRACE:
387 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED;
388 logit("Timeout before authentication for %s, "
389 "pid = %ld%s", child->id, (long)child->pid,
390 child_status);
391 break;
392 case EXIT_CHILD_CRASH:
393 penalty_type = SRCLIMIT_PENALTY_CRASH;
394 logit("Session process %ld unpriv child crash for %s%s",
395 (long)child->pid, child->id, child_status);
396 break;
397 case EXIT_AUTH_ATTEMPTED:
398 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL;
399 debug_f("preauth child %ld for %s exited "
400 "after unsuccessful auth attempt%s",
401 (long)child->pid, child->id, child_status);
402 break;
403 case EXIT_CONFIG_REFUSED:
404 penalty_type = SRCLIMIT_PENALTY_REFUSECONNECTION;
405 debug_f("preauth child %ld for %s prohibited by"
406 "RefuseConnection%s",
407 (long)child->pid, child->id, child_status);
408 break;
409 default:
410 penalty_type = SRCLIMIT_PENALTY_NOAUTH;
411 debug_f("preauth child %ld for %s exited "
412 "with status %d%s", (long)child->pid, child->id,
413 WEXITSTATUS(child->status), child_status);
414 break;
415 }
416 }
417
418 if (child->have_addr)
419 srclimit_penalise(&child->addr, penalty_type);
420
421 child->pid = -1;
422 child->have_status = 0;
423 if (child->pipefd == -1)
424 child_finish(child);
425 }
426
427 /* Reap all children that have exited; called after SIGCHLD */
428 static void
child_reap_all_exited(void)429 child_reap_all_exited(void)
430 {
431 int i;
432 pid_t pid;
433 int status;
434
435 if (children == NULL)
436 return;
437
438 for (;;) {
439 if ((pid = waitpid(-1, &status, WNOHANG)) == 0)
440 break;
441 else if (pid == -1) {
442 if (errno == EINTR || errno == EAGAIN)
443 continue;
444 if (errno != ECHILD)
445 error_f("waitpid: %s", strerror(errno));
446 break;
447 }
448 child_exit(pid, status);
449 }
450
451 for (i = 0; i < options.max_startups; i++) {
452 if (!children[i].have_status)
453 continue;
454 child_reap(&(children[i]));
455 }
456 }
457
458 static void
close_startup_pipes(void)459 close_startup_pipes(void)
460 {
461 int i;
462
463 if (children == NULL)
464 return;
465 for (i = 0; i < options.max_startups; i++) {
466 if (children[i].pipefd != -1)
467 child_close(&(children[i]), 1, 1);
468 }
469 }
470
471 /* Called after SIGINFO */
472 static void
show_info(void)473 show_info(void)
474 {
475 int i;
476 const char *child_status;
477
478 /* XXX print listening sockets here too */
479 if (children == NULL)
480 return;
481 logit("%d active startups", children_active);
482 for (i = 0; i < options.max_startups; i++) {
483 if (children[i].pipefd == -1 && children[i].pid <= 0)
484 continue;
485 if (children[i].config)
486 child_status = " (sending config)";
487 else if (children[i].keys)
488 child_status = " (sending keys)";
489 else if (children[i].early)
490 child_status = " (early)";
491 else
492 child_status = "";
493 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd,
494 (long)children[i].pid, children[i].id, child_status);
495 }
496 srclimit_penalty_info();
497 }
498
499 /*
500 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
501 * the effect is to reread the configuration file (and to regenerate
502 * the server key).
503 */
504
505 static void
sighup_handler(int sig)506 sighup_handler(int sig)
507 {
508 received_sighup = 1;
509 }
510
511 /*
512 * Called from the main program after receiving SIGHUP.
513 * Restarts the server.
514 */
515 __dead
516 static void
sighup_restart(void)517 sighup_restart(void)
518 {
519 logit("Received SIGHUP; restarting.");
520 if (options.pid_file != NULL)
521 unlink(options.pid_file);
522 close_listen_socks();
523 close_startup_pipes();
524 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
525 execv(saved_argv[0], saved_argv);
526 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
527 strerror(errno));
528 exit(1);
529 }
530
531 /*
532 * Generic signal handler for terminating signals in the master daemon.
533 */
534 static void
sigterm_handler(int sig)535 sigterm_handler(int sig)
536 {
537 received_sigterm = sig;
538 }
539
540 static void
siginfo_handler(int sig)541 siginfo_handler(int sig)
542 {
543 received_siginfo = 1;
544 }
545
546 static void
main_sigchld_handler(int sig)547 main_sigchld_handler(int sig)
548 {
549 received_sigchld = 1;
550 }
551
552 /*
553 * returns 1 if connection should be dropped, 0 otherwise.
554 * dropping starts at connection #max_startups_begin with a probability
555 * of (max_startups_rate/100). the probability increases linearly until
556 * all connections are dropped for startups > max_startups
557 */
558 static int
should_drop_connection(int startups)559 should_drop_connection(int startups)
560 {
561 int p, r;
562
563 if (startups < options.max_startups_begin)
564 return 0;
565 if (startups >= options.max_startups)
566 return 1;
567 if (options.max_startups_rate == 100)
568 return 1;
569
570 p = 100 - options.max_startups_rate;
571 p *= startups - options.max_startups_begin;
572 p /= options.max_startups - options.max_startups_begin;
573 p += options.max_startups_rate;
574 r = arc4random_uniform(100);
575
576 debug_f("p %d, r %d", p, r);
577 return (r < p) ? 1 : 0;
578 }
579
580 /*
581 * Check whether connection should be accepted by MaxStartups or for penalty.
582 * Returns 0 if the connection is accepted. If the connection is refused,
583 * returns 1 and attempts to send notification to client.
584 * Logs when the MaxStartups condition is entered or exited, and periodically
585 * while in that state.
586 */
587 static int
drop_connection(int sock,int startups,int notify_pipe)588 drop_connection(int sock, int startups, int notify_pipe)
589 {
590 static struct log_ratelimit_ctx ratelimit_maxstartups;
591 static struct log_ratelimit_ctx ratelimit_penalty;
592 static int init_done;
593 char *laddr, *raddr;
594 const char *reason = NULL, *subreason = NULL;
595 const char msg[] = "Not allowed at this time\r\n";
596 struct log_ratelimit_ctx *rl = NULL;
597 int ratelimited;
598 u_int ndropped;
599
600 if (!init_done) {
601 init_done = 1;
602 log_ratelimit_init(&ratelimit_maxstartups, 4, 60, 20, 5*60);
603 log_ratelimit_init(&ratelimit_penalty, 8, 60, 30, 2*60);
604 }
605
606 /* PerSourcePenalties */
607 if (!srclimit_penalty_check_allow(sock, &subreason)) {
608 reason = "PerSourcePenalties";
609 rl = &ratelimit_penalty;
610 } else {
611 /* MaxStartups */
612 if (!should_drop_connection(startups) &&
613 srclimit_check_allow(sock, notify_pipe) == 1)
614 return 0;
615 reason = "Maxstartups";
616 rl = &ratelimit_maxstartups;
617 }
618
619 laddr = get_local_ipaddr(sock);
620 raddr = get_peer_ipaddr(sock);
621 ratelimited = log_ratelimit(rl, time(NULL), NULL, &ndropped);
622 do_log2(ratelimited ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
623 "drop connection #%d from [%s]:%d on [%s]:%d %s",
624 startups,
625 raddr, get_peer_port(sock),
626 laddr, get_local_port(sock),
627 subreason != NULL ? subreason : reason);
628 free(laddr);
629 free(raddr);
630 if (ndropped != 0) {
631 logit("%s logging rate-limited: additional %u connections "
632 "dropped", reason, ndropped);
633 }
634
635 /* best-effort notification to client */
636 (void)write(sock, msg, sizeof(msg) - 1);
637 return 1;
638 }
639
640 __dead static void
usage(void)641 usage(void)
642 {
643 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION);
644 fprintf(stderr,
645 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n"
646 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
647 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
648 );
649 exit(1);
650 }
651
652 static struct sshbuf *
pack_hostkeys(void)653 pack_hostkeys(void)
654 {
655 struct sshbuf *m = NULL, *keybuf = NULL, *hostkeys = NULL;
656 int r;
657 u_int i;
658 size_t len;
659
660 if ((m = sshbuf_new()) == NULL ||
661 (keybuf = sshbuf_new()) == NULL ||
662 (hostkeys = sshbuf_new()) == NULL)
663 fatal_f("sshbuf_new failed");
664
665 /* pack hostkeys into a string. Empty key slots get empty strings */
666 for (i = 0; i < options.num_host_key_files; i++) {
667 /* private key */
668 sshbuf_reset(keybuf);
669 if (sensitive_data.host_keys[i] != NULL &&
670 (r = sshkey_private_serialize(sensitive_data.host_keys[i],
671 keybuf)) != 0)
672 fatal_fr(r, "serialize hostkey private");
673 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0)
674 fatal_fr(r, "compose hostkey private");
675 /* public key */
676 if (sensitive_data.host_pubkeys[i] != NULL) {
677 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i],
678 hostkeys)) != 0)
679 fatal_fr(r, "compose hostkey public");
680 } else {
681 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
682 fatal_fr(r, "compose hostkey empty public");
683 }
684 /* cert */
685 if (sensitive_data.host_certificates[i] != NULL) {
686 if ((r = sshkey_puts(
687 sensitive_data.host_certificates[i],
688 hostkeys)) != 0)
689 fatal_fr(r, "compose host cert");
690 } else {
691 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
692 fatal_fr(r, "compose host cert empty");
693 }
694 }
695
696 if ((r = sshbuf_put_u32(m, 0)) != 0 ||
697 (r = sshbuf_put_u8(m, 0)) != 0 ||
698 (r = sshbuf_put_stringb(m, hostkeys)) != 0)
699 fatal_fr(r, "compose message");
700 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff)
701 fatal_f("bad length %zu", len);
702 POKE_U32(sshbuf_mutable_ptr(m), len - 4);
703
704 sshbuf_free(keybuf);
705 sshbuf_free(hostkeys);
706 return m;
707 }
708
709 static struct sshbuf *
pack_config(struct sshbuf * conf)710 pack_config(struct sshbuf *conf)
711 {
712 struct sshbuf *m = NULL, *inc = NULL;
713 struct include_item *item = NULL;
714 size_t len;
715 int r;
716
717 debug3_f("d config len %zu", sshbuf_len(conf));
718
719 if ((m = sshbuf_new()) == NULL ||
720 (inc = sshbuf_new()) == NULL)
721 fatal_f("sshbuf_new failed");
722
723 /* pack includes into a string */
724 TAILQ_FOREACH(item, &includes, entry) {
725 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
726 (r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
727 (r = sshbuf_put_stringb(inc, item->contents)) != 0)
728 fatal_fr(r, "compose includes");
729 }
730
731 if ((r = sshbuf_put_u32(m, 0)) != 0 ||
732 (r = sshbuf_put_u8(m, 0)) != 0 ||
733 (r = sshbuf_put_stringb(m, conf)) != 0 ||
734 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 ||
735 (r = sshbuf_put_stringb(m, inc)) != 0)
736 fatal_fr(r, "compose config");
737
738 if ((len = sshbuf_len(m)) < 5 || len > 0xffffffff)
739 fatal_f("bad length %zu", len);
740 POKE_U32(sshbuf_mutable_ptr(m), len - 4);
741
742 sshbuf_free(inc);
743
744 debug3_f("done");
745 return m;
746 }
747
748 /*
749 * Protocol from reexec master to child:
750 * uint32 size
751 * uint8 type (ignored)
752 * string configuration
753 * uint64 timing_secret
754 * string included_files[] {
755 * string selector
756 * string filename
757 * string contents
758 * }
759 * Second message
760 * uint32 size
761 * uint8 type (ignored)
762 * string host_keys[] {
763 * string private_key
764 * string public_key
765 * string certificate
766 * }
767 */
768 /*
769 * This function is used only if inet_flag or debug_flag is set,
770 * otherwise the data is sent from the main poll loop.
771 * It sends the config from a child process back to the parent.
772 * The parent will read the config after exec.
773 */
774 static void
send_rexec_state(int fd)775 send_rexec_state(int fd)
776 {
777 struct sshbuf *keys;
778 u_int mlen;
779 pid_t pid;
780
781 if ((pid = fork()) == -1)
782 fatal_f("fork failed: %s", strerror(errno));
783 if (pid != 0)
784 return;
785
786 debug3_f("entering fd = %d config len %zu", fd,
787 sshbuf_len(config));
788
789 mlen = sshbuf_len(config);
790 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(config), mlen) != mlen)
791 error_f("write: %s", strerror(errno));
792
793 keys = pack_hostkeys();
794 mlen = sshbuf_len(keys);
795 if (atomicio(vwrite, fd, sshbuf_mutable_ptr(keys), mlen) != mlen)
796 error_f("write: %s", strerror(errno));
797
798 sshbuf_free(keys);
799 debug3_f("done");
800 exit(0);
801 }
802
803 /*
804 * Listen for TCP connections
805 */
806 static void
listen_on_addrs(struct listenaddr * la)807 listen_on_addrs(struct listenaddr *la)
808 {
809 int ret, listen_sock;
810 struct addrinfo *ai;
811 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
812 int socksize;
813 socklen_t socksizelen = sizeof(int);
814
815 for (ai = la->addrs; ai; ai = ai->ai_next) {
816 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
817 continue;
818 if (num_listen_socks >= MAX_LISTEN_SOCKS)
819 fatal("Too many listen sockets. "
820 "Enlarge MAX_LISTEN_SOCKS");
821 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
822 ntop, sizeof(ntop), strport, sizeof(strport),
823 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
824 error("getnameinfo failed: %.100s",
825 ssh_gai_strerror(ret));
826 continue;
827 }
828 /* Create socket for listening. */
829 listen_sock = socket(ai->ai_family, ai->ai_socktype,
830 ai->ai_protocol);
831 if (listen_sock == -1) {
832 /* kernel may not support ipv6 */
833 verbose("socket: %.100s", strerror(errno));
834 continue;
835 }
836 if (set_nonblock(listen_sock) == -1) {
837 close(listen_sock);
838 continue;
839 }
840 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
841 verbose("socket: CLOEXEC: %s", strerror(errno));
842 close(listen_sock);
843 continue;
844 }
845 /* Socket options */
846 set_reuseaddr(listen_sock);
847 if (la->rdomain != NULL &&
848 set_rdomain(listen_sock, la->rdomain) == -1) {
849 close(listen_sock);
850 continue;
851 }
852
853 debug("Bind to port %s on %s.", strport, ntop);
854
855 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF,
856 &socksize, &socksizelen);
857 debug("Server TCP RWIN socket size: %d", socksize);
858 debug("HPN Buffer Size: %d", options.hpn_buffer_size);
859
860 /* Bind the socket to the desired port. */
861 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) {
862 error("Bind to port %s on %s failed: %.200s.",
863 strport, ntop, strerror(errno));
864 close(listen_sock);
865 continue;
866 }
867 listen_socks[num_listen_socks] = listen_sock;
868 num_listen_socks++;
869
870 /* Start listening on the port. */
871 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1)
872 fatal("listen on [%s]:%s: %.100s",
873 ntop, strport, strerror(errno));
874 logit("Server listening on %s port %s%s%s.",
875 ntop, strport,
876 la->rdomain == NULL ? "" : " rdomain ",
877 la->rdomain == NULL ? "" : la->rdomain);
878 }
879 }
880
881 static void
server_listen(void)882 server_listen(void)
883 {
884 u_int i;
885
886 /* Initialise per-source limit tracking. */
887 srclimit_init(options.max_startups,
888 options.per_source_max_startups,
889 options.per_source_masklen_ipv4,
890 options.per_source_masklen_ipv6,
891 &options.per_source_penalty,
892 options.per_source_penalty_exempt);
893
894 for (i = 0; i < options.num_listen_addrs; i++) {
895 listen_on_addrs(&options.listen_addrs[i]);
896 freeaddrinfo(options.listen_addrs[i].addrs);
897 free(options.listen_addrs[i].rdomain);
898 memset(&options.listen_addrs[i], 0,
899 sizeof(options.listen_addrs[i]));
900 }
901 free(options.listen_addrs);
902 options.listen_addrs = NULL;
903 options.num_listen_addrs = 0;
904
905 if (!num_listen_socks)
906 fatal("Cannot bind any address.");
907 }
908
909 /*
910 * The main TCP accept loop. Note that, for the non-debug case, returns
911 * from this function are in a forked subprocess.
912 */
913 static void
server_accept_loop(int * sock_in,int * sock_out,int * newsock,int * config_s,int log_stderr)914 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s,
915 int log_stderr)
916 {
917 struct pollfd *pfd = NULL;
918 int i, ret, npfd, r;
919 int oactive = -1, listening = 0, lameduck = 0;
920 int *startup_pollfd;
921 ssize_t len;
922 const u_char *ptr;
923 char c = 0;
924 struct sockaddr_storage from;
925 struct early_child *child;
926 struct sshbuf *buf;
927 socklen_t fromlen;
928 sigset_t nsigset, osigset;
929
930 /* setup fd set for accept */
931 /* pipes connected to unauthenticated child sshd processes */
932 child_alloc();
933 startup_pollfd = xcalloc(options.max_startups, sizeof(int));
934
935 /*
936 * Prepare signal mask that we use to block signals that might set
937 * received_sigterm/hup/chld/info, so that we are guaranteed
938 * to immediately wake up the ppoll if a signal is received after
939 * the flag is checked.
940 */
941 sigemptyset(&nsigset);
942 sigaddset(&nsigset, SIGHUP);
943 sigaddset(&nsigset, SIGCHLD);
944 sigaddset(&nsigset, SIGINFO);
945 sigaddset(&nsigset, SIGTERM);
946 sigaddset(&nsigset, SIGQUIT);
947
948 /* sized for worst-case */
949 pfd = xcalloc(num_listen_socks + options.max_startups,
950 sizeof(struct pollfd));
951
952 /*
953 * Stay listening for connections until the system crashes or
954 * the daemon is killed with a signal.
955 */
956 for (;;) {
957 sigprocmask(SIG_BLOCK, &nsigset, &osigset);
958 if (received_sigterm) {
959 logit("Received signal %d; terminating.",
960 (int) received_sigterm);
961 close_listen_socks();
962 if (options.pid_file != NULL)
963 unlink(options.pid_file);
964 exit(received_sigterm == SIGTERM ? 0 : 255);
965 }
966 if (received_sigchld) {
967 child_reap_all_exited();
968 received_sigchld = 0;
969 }
970 if (received_siginfo) {
971 show_info();
972 received_siginfo = 0;
973 }
974 if (oactive != children_active) {
975 setproctitle("%s [listener] %d of %d-%d startups",
976 listener_proctitle, children_active,
977 options.max_startups_begin, options.max_startups);
978 oactive = children_active;
979 }
980 if (received_sighup) {
981 if (!lameduck) {
982 debug("Received SIGHUP; waiting for children");
983 close_listen_socks();
984 lameduck = 1;
985 }
986 if (listening <= 0) {
987 sigprocmask(SIG_SETMASK, &osigset, NULL);
988 sighup_restart();
989 }
990 }
991
992 for (i = 0; i < num_listen_socks; i++) {
993 pfd[i].fd = listen_socks[i];
994 pfd[i].events = POLLIN;
995 }
996 npfd = num_listen_socks;
997 for (i = 0; i < options.max_startups; i++) {
998 startup_pollfd[i] = -1;
999 if (children[i].pipefd != -1) {
1000 pfd[npfd].fd = children[i].pipefd;
1001 pfd[npfd].events = POLLIN;
1002 if (children[i].config != NULL ||
1003 children[i].keys != NULL)
1004 pfd[npfd].events |= POLLOUT;
1005 startup_pollfd[i] = npfd++;
1006 }
1007 }
1008
1009 /* Wait until a connection arrives or a child exits. */
1010 ret = ppoll(pfd, npfd, NULL, &osigset);
1011 if (ret == -1 && errno != EINTR) {
1012 error("ppoll: %.100s", strerror(errno));
1013 if (errno == EINVAL)
1014 cleanup_exit(1); /* can't recover */
1015 }
1016 sigprocmask(SIG_SETMASK, &osigset, NULL);
1017 if (ret == -1)
1018 continue;
1019
1020 for (i = 0; i < options.max_startups; i++) {
1021 if (children[i].pipefd == -1 ||
1022 startup_pollfd[i] == -1 ||
1023 !(pfd[startup_pollfd[i]].revents & POLLOUT))
1024 continue;
1025 if (children[i].config)
1026 buf = children[i].config;
1027 else if (children[i].keys)
1028 buf = children[i].keys;
1029 else {
1030 error_f("no buffer to send");
1031 continue;
1032 }
1033 ptr = sshbuf_ptr(buf);
1034 len = sshbuf_len(buf);
1035 ret = write(children[i].pipefd, ptr, len);
1036 if (ret == -1 && (errno == EINTR || errno == EAGAIN))
1037 continue;
1038 if (ret <= 0) {
1039 if (children[i].early)
1040 listening--;
1041 srclimit_done(children[i].pipefd);
1042 child_close(&(children[i]), 0, 0);
1043 continue;
1044 }
1045 if (ret == len) {
1046 /* finished sending buffer */
1047 sshbuf_free(buf);
1048 if (children[i].config == buf) {
1049 /* sent config, now send keys */
1050 children[i].config = NULL;
1051 children[i].keys = pack_hostkeys();
1052 } else if (children[i].keys == buf) {
1053 /* sent both config and keys */
1054 children[i].keys = NULL;
1055 } else {
1056 fatal("config buf not set");
1057 }
1058
1059 } else {
1060 if ((r = sshbuf_consume(buf, ret)) != 0)
1061 fatal_fr(r, "config buf inconsistent");
1062 }
1063 }
1064 for (i = 0; i < options.max_startups; i++) {
1065 if (children[i].pipefd == -1 ||
1066 startup_pollfd[i] == -1 ||
1067 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP)))
1068 continue;
1069 switch (read(children[i].pipefd, &c, sizeof(c))) {
1070 case -1:
1071 if (errno == EINTR || errno == EAGAIN)
1072 continue;
1073 if (errno != EPIPE) {
1074 error_f("startup pipe %d (fd=%d): "
1075 "read %s", i, children[i].pipefd,
1076 strerror(errno));
1077 }
1078 /* FALLTHROUGH */
1079 case 0:
1080 /* child exited preauth */
1081 if (children[i].early)
1082 listening--;
1083 srclimit_done(children[i].pipefd);
1084 child_close(&(children[i]), 0, 0);
1085 break;
1086 case 1:
1087 if (children[i].config) {
1088 error_f("startup pipe %d (fd=%d)"
1089 " early read", i, children[i].pipefd);
1090 if (children[i].early)
1091 listening--;
1092 if (children[i].pid > 0)
1093 kill(children[i].pid, SIGTERM);
1094 srclimit_done(children[i].pipefd);
1095 child_close(&(children[i]), 0, 0);
1096 break;
1097 }
1098 if (children[i].early && c == '\0') {
1099 /* child has finished preliminaries */
1100 listening--;
1101 children[i].early = 0;
1102 debug2_f("child %lu for %s received "
1103 "config", (long)children[i].pid,
1104 children[i].id);
1105 } else if (!children[i].early && c == '\001') {
1106 /* child has completed auth */
1107 debug2_f("child %lu for %s auth done",
1108 (long)children[i].pid,
1109 children[i].id);
1110 child_close(&(children[i]), 1, 0);
1111 } else {
1112 error_f("unexpected message 0x%02x "
1113 "child %ld for %s in state %d",
1114 (int)c, (long)children[i].pid,
1115 children[i].id, children[i].early);
1116 }
1117 break;
1118 }
1119 }
1120 for (i = 0; i < num_listen_socks; i++) {
1121 if (!(pfd[i].revents & POLLIN))
1122 continue;
1123 fromlen = sizeof(from);
1124 *newsock = accept(listen_socks[i],
1125 (struct sockaddr *)&from, &fromlen);
1126 if (*newsock == -1) {
1127 if (errno != EINTR && errno != EWOULDBLOCK &&
1128 errno != ECONNABORTED)
1129 error("accept: %.100s",
1130 strerror(errno));
1131 if (errno == EMFILE || errno == ENFILE)
1132 usleep(100 * 1000);
1133 continue;
1134 }
1135 if (unset_nonblock(*newsock) == -1) {
1136 close(*newsock);
1137 continue;
1138 }
1139 if (socketpair(AF_UNIX,
1140 SOCK_STREAM, 0, config_s) == -1) {
1141 error("reexec socketpair: %s",
1142 strerror(errno));
1143 close(*newsock);
1144 continue;
1145 }
1146 if (drop_connection(*newsock,
1147 children_active, config_s[0])) {
1148 close(*newsock);
1149 close(config_s[0]);
1150 close(config_s[1]);
1151 continue;
1152 }
1153
1154 /*
1155 * Got connection. Fork a child to handle it, unless
1156 * we are in debugging mode.
1157 */
1158 if (debug_flag) {
1159 /*
1160 * In debugging mode. Close the listening
1161 * socket, and start processing the
1162 * connection without forking.
1163 */
1164 debug("Server will not fork when running in debugging mode.");
1165 close_listen_socks();
1166 *sock_in = *newsock;
1167 *sock_out = *newsock;
1168 send_rexec_state(config_s[0]);
1169 close(config_s[0]);
1170 free(pfd);
1171 return;
1172 }
1173
1174 /*
1175 * Normal production daemon. Fork, and have
1176 * the child process the connection. The
1177 * parent continues listening.
1178 */
1179 set_nonblock(config_s[0]);
1180 listening++;
1181 child = child_register(config_s[0], *newsock);
1182 if ((child->pid = fork()) == 0) {
1183 /*
1184 * Child. Close the listening and
1185 * max_startup sockets. Start using
1186 * the accepted socket. Reinitialize
1187 * logging (since our pid has changed).
1188 * We return from this function to handle
1189 * the connection.
1190 */
1191 close_startup_pipes();
1192 close_listen_socks();
1193 *sock_in = *newsock;
1194 *sock_out = *newsock;
1195 log_init(__progname,
1196 options.log_level,
1197 options.log_facility,
1198 log_stderr);
1199 close(config_s[0]);
1200 free(pfd);
1201 return;
1202 }
1203
1204 /* Parent. Stay in the loop. */
1205 if (child->pid == -1)
1206 error("fork: %.100s", strerror(errno));
1207 else
1208 debug("Forked child %ld.", (long)child->pid);
1209
1210 close(config_s[1]);
1211 close(*newsock);
1212 }
1213 }
1214 }
1215
1216 static void
accumulate_host_timing_secret(struct sshbuf * server_cfg,struct sshkey * key)1217 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1218 struct sshkey *key)
1219 {
1220 static struct ssh_digest_ctx *ctx;
1221 u_char *hash;
1222 size_t len;
1223 struct sshbuf *buf;
1224 int r;
1225
1226 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1227 fatal_f("ssh_digest_start");
1228 if (key == NULL) { /* finalize */
1229 /* add server config in case we are using agent for host keys */
1230 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1231 sshbuf_len(server_cfg)) != 0)
1232 fatal_f("ssh_digest_update");
1233 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1234 hash = xmalloc(len);
1235 if (ssh_digest_final(ctx, hash, len) != 0)
1236 fatal_f("ssh_digest_final");
1237 options.timing_secret = PEEK_U64(hash);
1238 freezero(hash, len);
1239 ssh_digest_free(ctx);
1240 ctx = NULL;
1241 return;
1242 }
1243 if ((buf = sshbuf_new()) == NULL)
1244 fatal_f("could not allocate buffer");
1245 if ((r = sshkey_private_serialize(key, buf)) != 0)
1246 fatal_fr(r, "encode %s key", sshkey_ssh_name(key));
1247 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1248 fatal_f("ssh_digest_update");
1249 sshbuf_reset(buf);
1250 sshbuf_free(buf);
1251 }
1252
1253 static char *
prepare_proctitle(int ac,char ** av)1254 prepare_proctitle(int ac, char **av)
1255 {
1256 char *ret = NULL;
1257 int i;
1258
1259 for (i = 0; i < ac; i++)
1260 xextendf(&ret, " ", "%s", av[i]);
1261 return ret;
1262 }
1263
1264 __dead static void
print_config(struct connection_info * connection_info)1265 print_config(struct connection_info *connection_info)
1266 {
1267 connection_info->test = 1;
1268 parse_server_match_config(&options, &includes, connection_info);
1269 dump_config(&options);
1270 exit(0);
1271 }
1272
1273 /*
1274 * Main program for the daemon.
1275 */
1276 int
main(int ac,char ** av)1277 main(int ac, char **av)
1278 {
1279 extern char *optarg;
1280 extern int optind;
1281 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0;
1282 const char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1283 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0;
1284 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0;
1285 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0;
1286 char *args, *fp, *line, *logfile = NULL, **rexec_argv = NULL;
1287 struct stat sb;
1288 u_int i, j;
1289 mode_t new_umask;
1290 struct sshkey *key;
1291 struct sshkey *pubkey;
1292 struct utsname utsname;
1293 struct connection_info connection_info;
1294 sigset_t sigmask;
1295
1296 memset(&connection_info, 0, sizeof(connection_info));
1297
1298 sigemptyset(&sigmask);
1299 sigprocmask(SIG_SETMASK, &sigmask, NULL);
1300
1301 /* Save argv. */
1302 saved_argv = av;
1303 rexec_argc = ac;
1304
1305 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1306 sanitise_stdfd();
1307
1308 /* Initialize configuration options to their default values. */
1309 initialize_server_options(&options);
1310
1311 /* Parse command-line arguments. */
1312 args = argv_assemble(ac, av); /* logged later */
1313 while ((opt = getopt(ac, av,
1314 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) {
1315 switch (opt) {
1316 case '4':
1317 options.address_family = AF_INET;
1318 break;
1319 case '6':
1320 options.address_family = AF_INET6;
1321 break;
1322 case 'f':
1323 config_file_name = optarg;
1324 break;
1325 case 'c':
1326 servconf_add_hostcert("[command-line]", 0,
1327 &options, optarg);
1328 break;
1329 case 'd':
1330 if (debug_flag == 0) {
1331 debug_flag = 1;
1332 options.log_level = SYSLOG_LEVEL_DEBUG1;
1333 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1334 options.log_level++;
1335 break;
1336 case 'D':
1337 no_daemon_flag = 1;
1338 break;
1339 case 'G':
1340 do_dump_cfg = 1;
1341 break;
1342 case 'E':
1343 logfile = optarg;
1344 /* FALLTHROUGH */
1345 case 'e':
1346 log_stderr = 1;
1347 break;
1348 case 'i':
1349 inetd_flag = 1;
1350 break;
1351 case 'r':
1352 logit("-r option is deprecated");
1353 break;
1354 case 'R':
1355 fatal("-R not supported here");
1356 break;
1357 case 'Q':
1358 /* ignored */
1359 break;
1360 case 'q':
1361 options.log_level = SYSLOG_LEVEL_QUIET;
1362 break;
1363 case 'b':
1364 /* protocol 1, ignored */
1365 break;
1366 case 'p':
1367 options.ports_from_cmdline = 1;
1368 if (options.num_ports >= MAX_PORTS) {
1369 fprintf(stderr, "too many ports.\n");
1370 exit(1);
1371 }
1372 options.ports[options.num_ports++] = a2port(optarg);
1373 if (options.ports[options.num_ports-1] <= 0) {
1374 fprintf(stderr, "Bad port number.\n");
1375 exit(1);
1376 }
1377 break;
1378 case 'g':
1379 if ((options.login_grace_time = convtime(optarg)) == -1) {
1380 fprintf(stderr, "Invalid login grace time.\n");
1381 exit(1);
1382 }
1383 break;
1384 case 'k':
1385 /* protocol 1, ignored */
1386 break;
1387 case 'h':
1388 servconf_add_hostkey("[command-line]", 0,
1389 &options, optarg, 1);
1390 break;
1391 case 't':
1392 test_flag = 1;
1393 break;
1394 case 'T':
1395 test_flag = 2;
1396 break;
1397 case 'C':
1398 if (parse_server_match_testspec(&connection_info,
1399 optarg) == -1)
1400 exit(1);
1401 have_connection_info = 1;
1402 break;
1403 case 'u':
1404 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1405 if (utmp_len > HOST_NAME_MAX+1) {
1406 fprintf(stderr, "Invalid utmp length.\n");
1407 exit(1);
1408 }
1409 break;
1410 case 'o':
1411 line = xstrdup(optarg);
1412 if (process_server_config_line(&options, line,
1413 "command-line", 0, NULL, NULL, &includes) != 0)
1414 exit(1);
1415 free(line);
1416 break;
1417 case 'V':
1418 fprintf(stderr, "%s, %s\n",
1419 SSH_VERSION, SSH_OPENSSL_VERSION);
1420 exit(0);
1421 default:
1422 usage();
1423 break;
1424 }
1425 }
1426 if (!test_flag && !inetd_flag && !do_dump_cfg && !path_absolute(av[0]))
1427 fatal("sshd requires execution with an absolute path");
1428
1429 closefrom(STDERR_FILENO + 1);
1430
1431 /* Reserve fds we'll need later for reexec things */
1432 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1)
1433 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno));
1434 while (devnull < REEXEC_MIN_FREE_FD) {
1435 if ((devnull = dup(devnull)) == -1)
1436 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno));
1437 }
1438
1439 #ifdef WITH_OPENSSL
1440 OpenSSL_add_all_algorithms();
1441 #endif
1442
1443 /* If requested, redirect the logs to the specified logfile. */
1444 if (logfile != NULL) {
1445 char *cp, pid_s[32];
1446
1447 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
1448 cp = percent_expand(logfile,
1449 "p", pid_s,
1450 "P", "sshd",
1451 (char *)NULL);
1452 log_redirect_stderr_to(cp);
1453 free(cp);
1454 }
1455
1456 /*
1457 * Force logging to stderr until we have loaded the private host
1458 * key (unless started from inetd)
1459 */
1460 log_init(__progname,
1461 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1462 SYSLOG_LEVEL_INFO : options.log_level,
1463 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1464 SYSLOG_FACILITY_AUTH : options.log_facility,
1465 log_stderr || !inetd_flag || debug_flag);
1466
1467 sensitive_data.have_ssh2_key = 0;
1468
1469 /*
1470 * If we're not doing an extended test do not silently ignore connection
1471 * test params.
1472 */
1473 if (test_flag < 2 && have_connection_info)
1474 fatal("Config test connection parameter (-C) provided without "
1475 "test mode (-T)");
1476
1477 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1478 if (uname(&utsname) != 0) {
1479 memset(&utsname, 0, sizeof(utsname));
1480 strlcpy(utsname.sysname, "UNKNOWN", sizeof(utsname.sysname));
1481 }
1482 debug3("Running on %s %s %s %s", utsname.sysname, utsname.release,
1483 utsname.version, utsname.machine);
1484 debug3("Started with: %s", args);
1485 free(args);
1486
1487 /* Fetch our configuration */
1488 if ((cfg = sshbuf_new()) == NULL)
1489 fatal("sshbuf_new config failed");
1490 if (strcasecmp(config_file_name, "none") != 0)
1491 load_server_config(config_file_name, cfg);
1492
1493 parse_server_config(&options, config_file_name, cfg,
1494 &includes, NULL, 0);
1495
1496 /* Fill in default values for those options not explicitly set. */
1497 fill_default_server_options(&options);
1498
1499 /* Check that options are sensible */
1500 if (options.authorized_keys_command_user == NULL &&
1501 (options.authorized_keys_command != NULL &&
1502 strcasecmp(options.authorized_keys_command, "none") != 0))
1503 fatal("AuthorizedKeysCommand set without "
1504 "AuthorizedKeysCommandUser");
1505 if (options.authorized_principals_command_user == NULL &&
1506 (options.authorized_principals_command != NULL &&
1507 strcasecmp(options.authorized_principals_command, "none") != 0))
1508 fatal("AuthorizedPrincipalsCommand set without "
1509 "AuthorizedPrincipalsCommandUser");
1510
1511 /*
1512 * Check whether there is any path through configured auth methods.
1513 * Unfortunately it is not possible to verify this generally before
1514 * daemonisation in the presence of Match blocks, but this catches
1515 * and warns for trivial misconfigurations that could break login.
1516 */
1517 if (options.num_auth_methods != 0) {
1518 for (i = 0; i < options.num_auth_methods; i++) {
1519 if (auth2_methods_valid(options.auth_methods[i],
1520 1) == 0)
1521 break;
1522 }
1523 if (i >= options.num_auth_methods)
1524 fatal("AuthenticationMethods cannot be satisfied by "
1525 "enabled authentication methods");
1526 }
1527
1528 /* Check that there are no remaining arguments. */
1529 if (optind < ac) {
1530 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1531 exit(1);
1532 }
1533
1534 if (do_dump_cfg)
1535 print_config(&connection_info);
1536
1537 /* load host keys */
1538 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1539 sizeof(struct sshkey *));
1540 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1541 sizeof(struct sshkey *));
1542
1543 if (options.host_key_agent) {
1544 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1545 setenv(SSH_AUTHSOCKET_ENV_NAME,
1546 options.host_key_agent, 1);
1547 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1548 have_agent = 1;
1549 else
1550 error_r(r, "Could not connect to agent \"%s\"",
1551 options.host_key_agent);
1552 }
1553
1554 for (i = 0; i < options.num_host_key_files; i++) {
1555 int ll = options.host_key_file_userprovided[i] ?
1556 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1;
1557
1558 if (options.host_key_files[i] == NULL)
1559 continue;
1560 if ((r = sshkey_load_private(options.host_key_files[i], "",
1561 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1562 do_log2_r(r, ll, "Unable to load host key \"%s\"",
1563 options.host_key_files[i]);
1564 if (sshkey_is_sk(key) &&
1565 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
1566 debug("host key %s requires user presence, ignoring",
1567 options.host_key_files[i]);
1568 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
1569 }
1570 if (r == 0 && key != NULL &&
1571 (r = sshkey_shield_private(key)) != 0) {
1572 do_log2_r(r, ll, "Unable to shield host key \"%s\"",
1573 options.host_key_files[i]);
1574 sshkey_free(key);
1575 key = NULL;
1576 }
1577 if ((r = sshkey_load_public(options.host_key_files[i],
1578 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1579 do_log2_r(r, ll, "Unable to load host key \"%s\"",
1580 options.host_key_files[i]);
1581 if (pubkey != NULL && key != NULL) {
1582 if (!sshkey_equal(pubkey, key)) {
1583 error("Public key for %s does not match "
1584 "private key", options.host_key_files[i]);
1585 sshkey_free(pubkey);
1586 pubkey = NULL;
1587 }
1588 }
1589 if (pubkey == NULL && key != NULL) {
1590 if ((r = sshkey_from_private(key, &pubkey)) != 0)
1591 fatal_r(r, "Could not demote key: \"%s\"",
1592 options.host_key_files[i]);
1593 }
1594 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey,
1595 options.required_rsa_size)) != 0) {
1596 error_fr(r, "Host key %s", options.host_key_files[i]);
1597 sshkey_free(pubkey);
1598 sshkey_free(key);
1599 continue;
1600 }
1601 sensitive_data.host_keys[i] = key;
1602 sensitive_data.host_pubkeys[i] = pubkey;
1603
1604 if (key == NULL && pubkey != NULL && have_agent) {
1605 debug("will rely on agent for hostkey %s",
1606 options.host_key_files[i]);
1607 keytype = pubkey->type;
1608 } else if (key != NULL) {
1609 keytype = key->type;
1610 accumulate_host_timing_secret(cfg, key);
1611 } else {
1612 do_log2(ll, "Unable to load host key: %s",
1613 options.host_key_files[i]);
1614 sensitive_data.host_keys[i] = NULL;
1615 sensitive_data.host_pubkeys[i] = NULL;
1616 continue;
1617 }
1618
1619 switch (keytype) {
1620 case KEY_RSA:
1621 case KEY_DSA:
1622 case KEY_ECDSA:
1623 case KEY_ED25519:
1624 case KEY_ECDSA_SK:
1625 case KEY_ED25519_SK:
1626 case KEY_XMSS:
1627 if (have_agent || key != NULL)
1628 sensitive_data.have_ssh2_key = 1;
1629 break;
1630 }
1631 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1632 SSH_FP_DEFAULT)) == NULL)
1633 fatal("sshkey_fingerprint failed");
1634 debug("%s host key #%d: %s %s",
1635 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1636 free(fp);
1637 }
1638 accumulate_host_timing_secret(cfg, NULL);
1639 if (!sensitive_data.have_ssh2_key) {
1640 logit("sshd: no hostkeys available -- exiting.");
1641 exit(1);
1642 }
1643
1644 /*
1645 * Load certificates. They are stored in an array at identical
1646 * indices to the public keys that they relate to.
1647 */
1648 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1649 sizeof(struct sshkey *));
1650 for (i = 0; i < options.num_host_key_files; i++)
1651 sensitive_data.host_certificates[i] = NULL;
1652
1653 for (i = 0; i < options.num_host_cert_files; i++) {
1654 if (options.host_cert_files[i] == NULL)
1655 continue;
1656 if ((r = sshkey_load_public(options.host_cert_files[i],
1657 &key, NULL)) != 0) {
1658 error_r(r, "Could not load host certificate \"%s\"",
1659 options.host_cert_files[i]);
1660 continue;
1661 }
1662 if (!sshkey_is_cert(key)) {
1663 error("Certificate file is not a certificate: %s",
1664 options.host_cert_files[i]);
1665 sshkey_free(key);
1666 continue;
1667 }
1668 /* Find matching private key */
1669 for (j = 0; j < options.num_host_key_files; j++) {
1670 if (sshkey_equal_public(key,
1671 sensitive_data.host_pubkeys[j])) {
1672 sensitive_data.host_certificates[j] = key;
1673 break;
1674 }
1675 }
1676 if (j >= options.num_host_key_files) {
1677 error("No matching private key for certificate: %s",
1678 options.host_cert_files[i]);
1679 sshkey_free(key);
1680 continue;
1681 }
1682 sensitive_data.host_certificates[j] = key;
1683 debug("host certificate: #%u type %d %s", j, key->type,
1684 sshkey_type(key));
1685 }
1686
1687 /* Ensure privsep directory is correctly configured. */
1688 if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1689 fatal("Privilege separation user %s does not exist",
1690 SSH_PRIVSEP_USER);
1691 endpwent();
1692 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) ||
1693 (S_ISDIR(sb.st_mode) == 0))
1694 fatal("Missing privilege separation directory: %s",
1695 _PATH_PRIVSEP_CHROOT_DIR);
1696 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1697 fatal("%s must be owned by root and not group or "
1698 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1699
1700 if (test_flag > 1)
1701 print_config(&connection_info);
1702
1703 /* Configuration looks good, so exit if in test mode. */
1704 if (test_flag)
1705 exit(0);
1706
1707 /* Prepare arguments for sshd-session */
1708 if (rexec_argc < 0)
1709 fatal("rexec_argc %d < 0", rexec_argc);
1710 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *));
1711 /* Point to the sshd-session binary instead of sshd */
1712 rexec_argv[0] = options.sshd_session_path;
1713 for (i = 1; i < (u_int)rexec_argc; i++) {
1714 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1715 rexec_argv[i] = saved_argv[i];
1716 }
1717 rexec_argv[rexec_argc++] = __UNCONST("-R");
1718 rexec_argv[rexec_argc] = NULL;
1719 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR)))
1720 fatal("%s does not exist or is not executable", rexec_argv[0]);
1721 debug3("using %s for re-exec", rexec_argv[0]);
1722
1723 /* Ensure that the privsep binary exists now too. */
1724 if (stat(options.sshd_auth_path, &sb) != 0 ||
1725 !(sb.st_mode & (S_IXOTH|S_IXUSR))) {
1726 fatal("%s does not exist or is not executable",
1727 options.sshd_auth_path);
1728 }
1729
1730 listener_proctitle = prepare_proctitle(ac, av);
1731
1732 /* Ensure that umask disallows at least group and world write */
1733 new_umask = umask(0077) | 0022;
1734 (void) umask(new_umask);
1735
1736 /* Initialize the log (it is reinitialized below in case we forked). */
1737 if (debug_flag && !inetd_flag)
1738 log_stderr = 1;
1739 log_init(__progname, options.log_level,
1740 options.log_facility, log_stderr);
1741 for (i = 0; i < options.num_log_verbose; i++)
1742 log_verbose_add(options.log_verbose[i]);
1743
1744 /*
1745 * If not in debugging mode, not started from inetd and not already
1746 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1747 * terminal, and fork. The original process exits.
1748 */
1749 already_daemon = daemonized();
1750 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1751
1752 if (daemon(0, 0) == -1)
1753 fatal("daemon() failed: %.200s", strerror(errno));
1754
1755 disconnect_controlling_tty();
1756 }
1757 /* Reinitialize the log (because of the fork above). */
1758 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1759
1760 /*
1761 * Chdir to the root directory so that the current disk can be
1762 * unmounted if desired.
1763 */
1764 if (chdir("/") == -1)
1765 error("chdir(\"/\"): %s", strerror(errno));
1766
1767 /* ignore SIGPIPE */
1768 ssh_signal(SIGPIPE, SIG_IGN);
1769
1770 config = pack_config(cfg);
1771
1772 /* Get a connection, either from inetd or a listening TCP socket */
1773 if (inetd_flag) {
1774 /* Send configuration to ancestor sshd-session process */
1775 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1)
1776 fatal("socketpair: %s", strerror(errno));
1777 send_rexec_state(config_s[0]);
1778 close(config_s[0]);
1779 } else {
1780 server_listen();
1781
1782 ssh_signal(SIGHUP, sighup_handler);
1783 ssh_signal(SIGCHLD, main_sigchld_handler);
1784 ssh_signal(SIGTERM, sigterm_handler);
1785 ssh_signal(SIGQUIT, sigterm_handler);
1786 ssh_signal(SIGINFO, siginfo_handler);
1787
1788 /*
1789 * Write out the pid file after the sigterm handler
1790 * is setup and the listen sockets are bound
1791 */
1792 if (options.pid_file != NULL && !debug_flag) {
1793 FILE *f = fopen(options.pid_file, "w");
1794
1795 if (f == NULL) {
1796 error("Couldn't create pid file \"%s\": %s",
1797 options.pid_file, strerror(errno));
1798 } else {
1799 fprintf(f, "%ld\n", (long) getpid());
1800 fclose(f);
1801 }
1802 }
1803
1804 /* Accept a connection and return in a forked child */
1805 server_accept_loop(&sock_in, &sock_out,
1806 &newsock, config_s, log_stderr);
1807 }
1808
1809 /* This is the child processing a new connection. */
1810 setproctitle("%s", "[accepted]");
1811
1812 /*
1813 * Create a new session and process group since the 4.4BSD
1814 * setlogin() affects the entire process group. We don't
1815 * want the child to be able to affect the parent.
1816 */
1817 if (!debug_flag && !inetd_flag && setsid() == -1)
1818 error("setsid: %.100s", strerror(errno));
1819
1820 debug("rexec start in %d out %d newsock %d config_s %d/%d",
1821 sock_in, sock_out, newsock, config_s[0], config_s[1]);
1822 if (!inetd_flag) {
1823 if (dup2(newsock, STDIN_FILENO) == -1)
1824 fatal("dup2 stdin: %s", strerror(errno));
1825 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1)
1826 fatal("dup2 stdout: %s", strerror(errno));
1827 if (newsock > STDOUT_FILENO)
1828 close(newsock);
1829 }
1830 if (config_s[1] != REEXEC_CONFIG_PASS_FD) {
1831 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1)
1832 fatal("dup2 config_s: %s", strerror(errno));
1833 close(config_s[1]);
1834 }
1835 log_redirect_stderr_to(NULL);
1836 closefrom(REEXEC_MIN_FREE_FD);
1837
1838 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */
1839 execv(rexec_argv[0], rexec_argv);
1840
1841 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1842 }
1843
1844 /* server specific fatal cleanup */
1845 void
cleanup_exit(int i)1846 cleanup_exit(int i)
1847 {
1848 _exit(i);
1849 }
1850