1 /* $OpenBSD: sshd.c,v 1.609 2024/06/27 23:01:15 djm Exp $ */
2 /*
3 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
4 * Copyright (c) 2002 Niels Provos. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include "includes.h"
28
29 #include <sys/types.h>
30 #include <sys/ioctl.h>
31 #include <sys/socket.h>
32 #ifdef HAVE_SYS_STAT_H
33 # include <sys/stat.h>
34 #endif
35 #ifdef HAVE_SYS_TIME_H
36 # include <sys/time.h>
37 #endif
38 #include "openbsd-compat/sys-tree.h"
39 #include "openbsd-compat/sys-queue.h"
40 #include <sys/wait.h>
41
42 #include <errno.h>
43 #include <fcntl.h>
44 #include <netdb.h>
45 #ifdef HAVE_PATHS_H
46 #include <paths.h>
47 #endif
48 #include <grp.h>
49 #ifdef HAVE_POLL_H
50 #include <poll.h>
51 #endif
52 #include <pwd.h>
53 #include <signal.h>
54 #include <stdarg.h>
55 #include <stdio.h>
56 #include <stdlib.h>
57 #include <string.h>
58 #include <unistd.h>
59 #include <limits.h>
60
61 #ifdef WITH_OPENSSL
62 #include <openssl/evp.h>
63 #include <openssl/rand.h>
64 #include "openbsd-compat/openssl-compat.h"
65 #endif
66
67 #ifdef HAVE_SECUREWARE
68 #include <sys/security.h>
69 #include <prot.h>
70 #endif
71
72 #include "xmalloc.h"
73 #include "ssh.h"
74 #include "sshpty.h"
75 #include "log.h"
76 #include "sshbuf.h"
77 #include "misc.h"
78 #include "servconf.h"
79 #include "compat.h"
80 #include "digest.h"
81 #include "sshkey.h"
82 #include "authfile.h"
83 #include "pathnames.h"
84 #include "canohost.h"
85 #include "hostfile.h"
86 #include "auth.h"
87 #include "authfd.h"
88 #include "msg.h"
89 #include "version.h"
90 #include "ssherr.h"
91 #include "sk-api.h"
92 #include "addr.h"
93 #include "srclimit.h"
94
95 /* Re-exec fds */
96 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
97 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
98 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
99 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
100
101 extern char *__progname;
102
103 /* Server configuration options. */
104 ServerOptions options;
105
106 /*
107 * Debug mode flag. This can be set on the command line. If debug
108 * mode is enabled, extra debugging output will be sent to the system
109 * log, the daemon will not go to background, and will exit after processing
110 * the first connection.
111 */
112 int debug_flag = 0;
113
114 /* Saved arguments to main(). */
115 static char **saved_argv;
116 static int saved_argc;
117
118 /*
119 * The sockets that the server is listening; this is used in the SIGHUP
120 * signal handler.
121 */
122 #define MAX_LISTEN_SOCKS 16
123 static int listen_socks[MAX_LISTEN_SOCKS];
124 static int num_listen_socks = 0;
125
126 /*
127 * Any really sensitive data in the application is contained in this
128 * structure. The idea is that this structure could be locked into memory so
129 * that the pages do not get written into swap. However, there are some
130 * problems. The private key contains BIGNUMs, and we do not (in principle)
131 * have access to the internals of them, and locking just the structure is
132 * not very useful. Currently, memory locking is not implemented.
133 */
134 struct {
135 struct sshkey **host_keys; /* all private host keys */
136 struct sshkey **host_pubkeys; /* all public host keys */
137 struct sshkey **host_certificates; /* all public host certificates */
138 int have_ssh2_key;
139 } sensitive_data;
140
141 /* This is set to true when a signal is received. */
142 static volatile sig_atomic_t received_siginfo = 0;
143 static volatile sig_atomic_t received_sigchld = 0;
144 static volatile sig_atomic_t received_sighup = 0;
145 static volatile sig_atomic_t received_sigterm = 0;
146
147 /* record remote hostname or ip */
148 u_int utmp_len = HOST_NAME_MAX+1;
149
150 /*
151 * The early_child/children array below is used for tracking children of the
152 * listening sshd process early in their lifespans, before they have
153 * completed authentication. This tracking is needed for four things:
154 *
155 * 1) Implementing the MaxStartups limit of concurrent unauthenticated
156 * connections.
157 * 2) Avoiding a race condition for SIGHUP processing, where child processes
158 * may have listen_socks open that could collide with main listener process
159 * after it restarts.
160 * 3) Ensuring that rexec'd sshd processes have received their initial state
161 * from the parent listen process before handling SIGHUP.
162 * 4) Tracking and logging unsuccessful exits from the preauth sshd monitor,
163 * including and especially those for LoginGraceTime timeouts.
164 *
165 * Child processes signal that they have completed closure of the listen_socks
166 * and (if applicable) received their rexec state by sending a char over their
167 * sock.
168 *
169 * Child processes signal that authentication has completed by sending a
170 * second char over the socket before closing it, otherwise the listener will
171 * continue tracking the child (and using up a MaxStartups slot) until the
172 * preauth subprocess exits, whereupon the listener will log its exit status.
173 * preauth processes will exit with a status of EXIT_LOGIN_GRACE to indicate
174 * they did not authenticate before the LoginGraceTime alarm fired.
175 */
176 struct early_child {
177 int pipefd;
178 int early; /* Indicates child closed listener */
179 char *id; /* human readable connection identifier */
180 pid_t pid;
181 struct xaddr addr;
182 int have_addr;
183 int status, have_status;
184 };
185 static struct early_child *children;
186 static int children_active;
187 static int startup_pipe = -1; /* in child */
188
189 /* sshd_config buffer */
190 struct sshbuf *cfg;
191
192 /* Included files from the configuration file */
193 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes);
194
195 /* message to be displayed after login */
196 struct sshbuf *loginmsg;
197
198 /* Unprivileged user */
199 struct passwd *privsep_pw = NULL;
200
201 static char *listener_proctitle;
202
203 /*
204 * Close all listening sockets
205 */
206 static void
close_listen_socks(void)207 close_listen_socks(void)
208 {
209 int i;
210
211 for (i = 0; i < num_listen_socks; i++)
212 close(listen_socks[i]);
213 num_listen_socks = 0;
214 }
215
216 /* Allocate and initialise the children array */
217 static void
child_alloc(void)218 child_alloc(void)
219 {
220 int i;
221
222 children = xcalloc(options.max_startups, sizeof(*children));
223 for (i = 0; i < options.max_startups; i++) {
224 children[i].pipefd = -1;
225 children[i].pid = -1;
226 }
227 }
228
229 /* Register a new connection in the children array; child pid comes later */
230 static struct early_child *
child_register(int pipefd,int sockfd)231 child_register(int pipefd, int sockfd)
232 {
233 int i, lport, rport;
234 char *laddr = NULL, *raddr = NULL;
235 struct early_child *child = NULL;
236 struct sockaddr_storage addr;
237 socklen_t addrlen = sizeof(addr);
238 struct sockaddr *sa = (struct sockaddr *)&addr;
239
240 for (i = 0; i < options.max_startups; i++) {
241 if (children[i].pipefd != -1 || children[i].pid > 0)
242 continue;
243 child = &(children[i]);
244 break;
245 }
246 if (child == NULL) {
247 fatal_f("error: accepted connection when all %d child "
248 " slots full", options.max_startups);
249 }
250 child->pipefd = pipefd;
251 child->early = 1;
252 /* record peer address, if available */
253 if (getpeername(sockfd, sa, &addrlen) == 0 &&
254 addr_sa_to_xaddr(sa, addrlen, &child->addr) == 0)
255 child->have_addr = 1;
256 /* format peer address string for logs */
257 if ((lport = get_local_port(sockfd)) == 0 ||
258 (rport = get_peer_port(sockfd)) == 0) {
259 /* Not a TCP socket */
260 raddr = get_peer_ipaddr(sockfd);
261 xasprintf(&child->id, "connection from %s", raddr);
262 } else {
263 laddr = get_local_ipaddr(sockfd);
264 raddr = get_peer_ipaddr(sockfd);
265 xasprintf(&child->id, "connection from %s to %s", laddr, raddr);
266 }
267 free(laddr);
268 free(raddr);
269 if (++children_active > options.max_startups)
270 fatal_f("internal error: more children than max_startups");
271
272 return child;
273 }
274
275 /*
276 * Finally free a child entry. Don't call this directly.
277 */
278 static void
child_finish(struct early_child * child)279 child_finish(struct early_child *child)
280 {
281 if (children_active == 0)
282 fatal_f("internal error: children_active underflow");
283 if (child->pipefd != -1)
284 close(child->pipefd);
285 free(child->id);
286 memset(child, '\0', sizeof(*child));
287 child->pipefd = -1;
288 child->pid = -1;
289 children_active--;
290 }
291
292 /*
293 * Close a child's pipe. This will not stop tracking the child immediately
294 * (it will still be tracked for waitpid()) unless force_final is set, or
295 * child has already exited.
296 */
297 static void
child_close(struct early_child * child,int force_final,int quiet)298 child_close(struct early_child *child, int force_final, int quiet)
299 {
300 if (!quiet)
301 debug_f("enter%s", force_final ? " (forcing)" : "");
302 if (child->pipefd != -1) {
303 close(child->pipefd);
304 child->pipefd = -1;
305 }
306 if (child->pid == -1 || force_final)
307 child_finish(child);
308 }
309
310 /* Record a child exit. Safe to call from signal handlers */
311 static void
child_exit(pid_t pid,int status)312 child_exit(pid_t pid, int status)
313 {
314 int i;
315
316 if (children == NULL || pid <= 0)
317 return;
318 for (i = 0; i < options.max_startups; i++) {
319 if (children[i].pid == pid) {
320 children[i].have_status = 1;
321 children[i].status = status;
322 break;
323 }
324 }
325 }
326
327 /*
328 * Reap a child entry that has exited, as previously flagged
329 * using child_exit().
330 * Handles logging of exit condition and will finalise the child if its pipe
331 * had already been closed.
332 */
333 static void
child_reap(struct early_child * child)334 child_reap(struct early_child *child)
335 {
336 LogLevel level = SYSLOG_LEVEL_DEBUG1;
337 int was_crash, penalty_type = SRCLIMIT_PENALTY_NONE;
338
339 /* Log exit information */
340 if (WIFSIGNALED(child->status)) {
341 /*
342 * Increase logging for signals potentially associated
343 * with serious conditions.
344 */
345 if ((was_crash = signal_is_crash(WTERMSIG(child->status))))
346 level = SYSLOG_LEVEL_ERROR;
347 do_log2(level, "session process %ld for %s killed by "
348 "signal %d%s", (long)child->pid, child->id,
349 WTERMSIG(child->status), child->early ? " (early)" : "");
350 if (was_crash)
351 penalty_type = SRCLIMIT_PENALTY_CRASH;
352 } else if (!WIFEXITED(child->status)) {
353 penalty_type = SRCLIMIT_PENALTY_CRASH;
354 error("session process %ld for %s terminated abnormally, "
355 "status=0x%x%s", (long)child->pid, child->id, child->status,
356 child->early ? " (early)" : "");
357 } else {
358 /* Normal exit. We care about the status */
359 switch (WEXITSTATUS(child->status)) {
360 case 0:
361 debug3_f("preauth child %ld for %s completed "
362 "normally %s", (long)child->pid, child->id,
363 child->early ? " (early)" : "");
364 break;
365 case EXIT_LOGIN_GRACE:
366 penalty_type = SRCLIMIT_PENALTY_GRACE_EXCEEDED;
367 logit("Timeout before authentication for %s, "
368 "pid = %ld%s", child->id, (long)child->pid,
369 child->early ? " (early)" : "");
370 break;
371 case EXIT_CHILD_CRASH:
372 penalty_type = SRCLIMIT_PENALTY_CRASH;
373 logit("Session process %ld unpriv child crash for %s%s",
374 (long)child->pid, child->id,
375 child->early ? " (early)" : "");
376 break;
377 case EXIT_AUTH_ATTEMPTED:
378 penalty_type = SRCLIMIT_PENALTY_AUTHFAIL;
379 debug_f("preauth child %ld for %s exited "
380 "after unsuccessful auth attempt %s",
381 (long)child->pid, child->id,
382 child->early ? " (early)" : "");
383 break;
384 default:
385 penalty_type = SRCLIMIT_PENALTY_NOAUTH;
386 debug_f("preauth child %ld for %s exited "
387 "with status %d%s", (long)child->pid, child->id,
388 WEXITSTATUS(child->status),
389 child->early ? " (early)" : "");
390 break;
391 }
392 }
393
394 if (child->have_addr)
395 srclimit_penalise(&child->addr, penalty_type);
396
397 child->pid = -1;
398 child->have_status = 0;
399 if (child->pipefd == -1)
400 child_finish(child);
401 }
402
403 /* Reap all children that have exited; called after SIGCHLD */
404 static void
child_reap_all_exited(void)405 child_reap_all_exited(void)
406 {
407 int i;
408 pid_t pid;
409 int status;
410
411 if (children == NULL)
412 return;
413
414 for (;;) {
415 if ((pid = waitpid(-1, &status, WNOHANG)) == 0)
416 break;
417 else if (pid == -1) {
418 if (errno == EINTR || errno == EAGAIN)
419 continue;
420 if (errno != ECHILD)
421 error_f("waitpid: %s", strerror(errno));
422 break;
423 }
424 child_exit(pid, status);
425 }
426
427 for (i = 0; i < options.max_startups; i++) {
428 if (!children[i].have_status)
429 continue;
430 child_reap(&(children[i]));
431 }
432 }
433
434 static void
close_startup_pipes(void)435 close_startup_pipes(void)
436 {
437 int i;
438
439 if (children == NULL)
440 return;
441 for (i = 0; i < options.max_startups; i++) {
442 if (children[i].pipefd != -1)
443 child_close(&(children[i]), 1, 1);
444 }
445 }
446
447 /* Called after SIGINFO */
448 static void
show_info(void)449 show_info(void)
450 {
451 int i;
452
453 /* XXX print listening sockets here too */
454 if (children == NULL)
455 return;
456 logit("%d active startups", children_active);
457 for (i = 0; i < options.max_startups; i++) {
458 if (children[i].pipefd == -1 && children[i].pid <= 0)
459 continue;
460 logit("child %d: fd=%d pid=%ld %s%s", i, children[i].pipefd,
461 (long)children[i].pid, children[i].id,
462 children[i].early ? " (early)" : "");
463 }
464 srclimit_penalty_info();
465 }
466
467 /*
468 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
469 * the effect is to reread the configuration file (and to regenerate
470 * the server key).
471 */
472
473 static void
sighup_handler(int sig)474 sighup_handler(int sig)
475 {
476 received_sighup = 1;
477 }
478
479 /*
480 * Called from the main program after receiving SIGHUP.
481 * Restarts the server.
482 */
483 static void
sighup_restart(void)484 sighup_restart(void)
485 {
486 logit("Received SIGHUP; restarting.");
487 if (options.pid_file != NULL)
488 unlink(options.pid_file);
489 platform_pre_restart();
490 close_listen_socks();
491 close_startup_pipes();
492 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */
493 execv(saved_argv[0], saved_argv);
494 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
495 strerror(errno));
496 exit(1);
497 }
498
499 /*
500 * Generic signal handler for terminating signals in the master daemon.
501 */
502 static void
sigterm_handler(int sig)503 sigterm_handler(int sig)
504 {
505 received_sigterm = sig;
506 }
507
508 #ifdef SIGINFO
509 static void
siginfo_handler(int sig)510 siginfo_handler(int sig)
511 {
512 received_siginfo = 1;
513 }
514 #endif
515
516 static void
main_sigchld_handler(int sig)517 main_sigchld_handler(int sig)
518 {
519 received_sigchld = 1;
520 }
521
522 /*
523 * returns 1 if connection should be dropped, 0 otherwise.
524 * dropping starts at connection #max_startups_begin with a probability
525 * of (max_startups_rate/100). the probability increases linearly until
526 * all connections are dropped for startups > max_startups
527 */
528 static int
should_drop_connection(int startups)529 should_drop_connection(int startups)
530 {
531 int p, r;
532
533 if (startups < options.max_startups_begin)
534 return 0;
535 if (startups >= options.max_startups)
536 return 1;
537 if (options.max_startups_rate == 100)
538 return 1;
539
540 p = 100 - options.max_startups_rate;
541 p *= startups - options.max_startups_begin;
542 p /= options.max_startups - options.max_startups_begin;
543 p += options.max_startups_rate;
544 r = arc4random_uniform(100);
545
546 debug_f("p %d, r %d", p, r);
547 return (r < p) ? 1 : 0;
548 }
549
550 /*
551 * Check whether connection should be accepted by MaxStartups or for penalty.
552 * Returns 0 if the connection is accepted. If the connection is refused,
553 * returns 1 and attempts to send notification to client.
554 * Logs when the MaxStartups condition is entered or exited, and periodically
555 * while in that state.
556 */
557 static int
drop_connection(int sock,int startups,int notify_pipe)558 drop_connection(int sock, int startups, int notify_pipe)
559 {
560 char *laddr, *raddr;
561 const char *reason = NULL, msg[] = "Not allowed at this time\r\n";
562 static time_t last_drop, first_drop;
563 static u_int ndropped;
564 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE;
565 time_t now;
566
567 if (!srclimit_penalty_check_allow(sock, &reason)) {
568 drop_level = SYSLOG_LEVEL_INFO;
569 goto handle;
570 }
571
572 now = monotime();
573 if (!should_drop_connection(startups) &&
574 srclimit_check_allow(sock, notify_pipe) == 1) {
575 if (last_drop != 0 &&
576 startups < options.max_startups_begin - 1) {
577 /* XXX maybe need better hysteresis here */
578 logit("exited MaxStartups throttling after %s, "
579 "%u connections dropped",
580 fmt_timeframe(now - first_drop), ndropped);
581 last_drop = 0;
582 }
583 return 0;
584 }
585
586 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60)
587 if (last_drop == 0) {
588 error("beginning MaxStartups throttling");
589 drop_level = SYSLOG_LEVEL_INFO;
590 first_drop = now;
591 ndropped = 0;
592 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) {
593 /* Periodic logs */
594 error("in MaxStartups throttling for %s, "
595 "%u connections dropped",
596 fmt_timeframe(now - first_drop), ndropped + 1);
597 drop_level = SYSLOG_LEVEL_INFO;
598 }
599 last_drop = now;
600 ndropped++;
601 reason = "past Maxstartups";
602
603 handle:
604 laddr = get_local_ipaddr(sock);
605 raddr = get_peer_ipaddr(sock);
606 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d %s",
607 startups,
608 raddr, get_peer_port(sock),
609 laddr, get_local_port(sock),
610 reason);
611 free(laddr);
612 free(raddr);
613 /* best-effort notification to client */
614 (void)write(sock, msg, sizeof(msg) - 1);
615 return 1;
616 }
617
618 static void
usage(void)619 usage(void)
620 {
621 fprintf(stderr, "%s, %s\n", SSH_RELEASE, SSH_OPENSSL_VERSION);
622 fprintf(stderr,
623 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n"
624 " [-E log_file] [-f config_file] [-g login_grace_time]\n"
625 " [-h host_key_file] [-o option] [-p port] [-u len]\n"
626 );
627 exit(1);
628 }
629
630 static struct sshbuf *
pack_hostkeys(void)631 pack_hostkeys(void)
632 {
633 struct sshbuf *keybuf = NULL, *hostkeys = NULL;
634 int r;
635 u_int i;
636
637 if ((keybuf = sshbuf_new()) == NULL ||
638 (hostkeys = sshbuf_new()) == NULL)
639 fatal_f("sshbuf_new failed");
640
641 /* pack hostkeys into a string. Empty key slots get empty strings */
642 for (i = 0; i < options.num_host_key_files; i++) {
643 /* private key */
644 sshbuf_reset(keybuf);
645 if (sensitive_data.host_keys[i] != NULL &&
646 (r = sshkey_private_serialize(sensitive_data.host_keys[i],
647 keybuf)) != 0)
648 fatal_fr(r, "serialize hostkey private");
649 if ((r = sshbuf_put_stringb(hostkeys, keybuf)) != 0)
650 fatal_fr(r, "compose hostkey private");
651 /* public key */
652 if (sensitive_data.host_pubkeys[i] != NULL) {
653 if ((r = sshkey_puts(sensitive_data.host_pubkeys[i],
654 hostkeys)) != 0)
655 fatal_fr(r, "compose hostkey public");
656 } else {
657 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
658 fatal_fr(r, "compose hostkey empty public");
659 }
660 /* cert */
661 if (sensitive_data.host_certificates[i] != NULL) {
662 if ((r = sshkey_puts(
663 sensitive_data.host_certificates[i],
664 hostkeys)) != 0)
665 fatal_fr(r, "compose host cert");
666 } else {
667 if ((r = sshbuf_put_string(hostkeys, NULL, 0)) != 0)
668 fatal_fr(r, "compose host cert empty");
669 }
670 }
671
672 sshbuf_free(keybuf);
673 return hostkeys;
674 }
675
676 static void
send_rexec_state(int fd,struct sshbuf * conf)677 send_rexec_state(int fd, struct sshbuf *conf)
678 {
679 struct sshbuf *m = NULL, *inc = NULL, *hostkeys = NULL;
680 struct include_item *item = NULL;
681 int r, sz;
682
683 debug3_f("entering fd = %d config len %zu", fd,
684 sshbuf_len(conf));
685
686 if ((m = sshbuf_new()) == NULL ||
687 (inc = sshbuf_new()) == NULL)
688 fatal_f("sshbuf_new failed");
689
690 /* pack includes into a string */
691 TAILQ_FOREACH(item, &includes, entry) {
692 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 ||
693 (r = sshbuf_put_cstring(inc, item->filename)) != 0 ||
694 (r = sshbuf_put_stringb(inc, item->contents)) != 0)
695 fatal_fr(r, "compose includes");
696 }
697
698 hostkeys = pack_hostkeys();
699
700 /*
701 * Protocol from reexec master to child:
702 * string configuration
703 * uint64 timing_secret
704 * string host_keys[] {
705 * string private_key
706 * string public_key
707 * string certificate
708 * }
709 * string included_files[] {
710 * string selector
711 * string filename
712 * string contents
713 * }
714 */
715 if ((r = sshbuf_put_stringb(m, conf)) != 0 ||
716 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 ||
717 (r = sshbuf_put_stringb(m, hostkeys)) != 0 ||
718 (r = sshbuf_put_stringb(m, inc)) != 0)
719 fatal_fr(r, "compose config");
720
721 /* We need to fit the entire message inside the socket send buffer */
722 sz = ROUNDUP(sshbuf_len(m) + 5, 16*1024);
723 if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sz, sizeof sz) == -1)
724 fatal_f("setsockopt SO_SNDBUF: %s", strerror(errno));
725
726 if (ssh_msg_send(fd, 0, m) == -1)
727 error_f("ssh_msg_send failed");
728
729 sshbuf_free(m);
730 sshbuf_free(inc);
731 sshbuf_free(hostkeys);
732
733 debug3_f("done");
734 }
735
736 /*
737 * Listen for TCP connections
738 */
739 static void
listen_on_addrs(struct listenaddr * la)740 listen_on_addrs(struct listenaddr *la)
741 {
742 int ret, listen_sock;
743 struct addrinfo *ai;
744 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
745
746 for (ai = la->addrs; ai; ai = ai->ai_next) {
747 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
748 continue;
749 if (num_listen_socks >= MAX_LISTEN_SOCKS)
750 fatal("Too many listen sockets. "
751 "Enlarge MAX_LISTEN_SOCKS");
752 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
753 ntop, sizeof(ntop), strport, sizeof(strport),
754 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
755 error("getnameinfo failed: %.100s",
756 ssh_gai_strerror(ret));
757 continue;
758 }
759 /* Create socket for listening. */
760 listen_sock = socket(ai->ai_family, ai->ai_socktype,
761 ai->ai_protocol);
762 if (listen_sock == -1) {
763 /* kernel may not support ipv6 */
764 verbose("socket: %.100s", strerror(errno));
765 continue;
766 }
767 if (set_nonblock(listen_sock) == -1) {
768 close(listen_sock);
769 continue;
770 }
771 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) {
772 verbose("socket: CLOEXEC: %s", strerror(errno));
773 close(listen_sock);
774 continue;
775 }
776 /* Socket options */
777 set_reuseaddr(listen_sock);
778 if (la->rdomain != NULL &&
779 set_rdomain(listen_sock, la->rdomain) == -1) {
780 close(listen_sock);
781 continue;
782 }
783
784 /* Only communicate in IPv6 over AF_INET6 sockets. */
785 if (ai->ai_family == AF_INET6)
786 sock_set_v6only(listen_sock);
787
788 debug("Bind to port %s on %s.", strport, ntop);
789
790 /* Bind the socket to the desired port. */
791 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) {
792 error("Bind to port %s on %s failed: %.200s.",
793 strport, ntop, strerror(errno));
794 close(listen_sock);
795 continue;
796 }
797 listen_socks[num_listen_socks] = listen_sock;
798 num_listen_socks++;
799
800 /* Start listening on the port. */
801 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1)
802 fatal("listen on [%s]:%s: %.100s",
803 ntop, strport, strerror(errno));
804 logit("Server listening on %s port %s%s%s.",
805 ntop, strport,
806 la->rdomain == NULL ? "" : " rdomain ",
807 la->rdomain == NULL ? "" : la->rdomain);
808 }
809 }
810
811 static void
server_listen(void)812 server_listen(void)
813 {
814 u_int i;
815
816 /* Initialise per-source limit tracking. */
817 srclimit_init(options.max_startups,
818 options.per_source_max_startups,
819 options.per_source_masklen_ipv4,
820 options.per_source_masklen_ipv6,
821 &options.per_source_penalty,
822 options.per_source_penalty_exempt);
823
824 for (i = 0; i < options.num_listen_addrs; i++) {
825 listen_on_addrs(&options.listen_addrs[i]);
826 freeaddrinfo(options.listen_addrs[i].addrs);
827 free(options.listen_addrs[i].rdomain);
828 memset(&options.listen_addrs[i], 0,
829 sizeof(options.listen_addrs[i]));
830 }
831 free(options.listen_addrs);
832 options.listen_addrs = NULL;
833 options.num_listen_addrs = 0;
834
835 if (!num_listen_socks)
836 fatal("Cannot bind any address.");
837 }
838
839 /*
840 * The main TCP accept loop. Note that, for the non-debug case, returns
841 * from this function are in a forked subprocess.
842 */
843 static void
server_accept_loop(int * sock_in,int * sock_out,int * newsock,int * config_s,int log_stderr)844 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s,
845 int log_stderr)
846 {
847 struct pollfd *pfd = NULL;
848 int i, ret, npfd;
849 int oactive = -1, listening = 0, lameduck = 0;
850 int startup_p[2] = { -1 , -1 }, *startup_pollfd;
851 char c = 0;
852 struct sockaddr_storage from;
853 struct early_child *child;
854 socklen_t fromlen;
855 u_char rnd[256];
856 sigset_t nsigset, osigset;
857
858 /* pipes connected to unauthenticated child sshd processes */
859 child_alloc();
860 startup_pollfd = xcalloc(options.max_startups, sizeof(int));
861
862 /*
863 * Prepare signal mask that we use to block signals that might set
864 * received_sigterm/hup/chld/info, so that we are guaranteed
865 * to immediately wake up the ppoll if a signal is received after
866 * the flag is checked.
867 */
868 sigemptyset(&nsigset);
869 sigaddset(&nsigset, SIGHUP);
870 sigaddset(&nsigset, SIGCHLD);
871 #ifdef SIGINFO
872 sigaddset(&nsigset, SIGINFO);
873 #endif
874 sigaddset(&nsigset, SIGTERM);
875 sigaddset(&nsigset, SIGQUIT);
876
877 /* sized for worst-case */
878 pfd = xcalloc(num_listen_socks + options.max_startups,
879 sizeof(struct pollfd));
880
881 /*
882 * Stay listening for connections until the system crashes or
883 * the daemon is killed with a signal.
884 */
885 for (;;) {
886 sigprocmask(SIG_BLOCK, &nsigset, &osigset);
887 if (received_sigterm) {
888 logit("Received signal %d; terminating.",
889 (int) received_sigterm);
890 close_listen_socks();
891 if (options.pid_file != NULL)
892 unlink(options.pid_file);
893 exit(received_sigterm == SIGTERM ? 0 : 255);
894 }
895 if (received_sigchld) {
896 child_reap_all_exited();
897 received_sigchld = 0;
898 }
899 if (received_siginfo) {
900 show_info();
901 received_siginfo = 0;
902 }
903 if (oactive != children_active) {
904 setproctitle("%s [listener] %d of %d-%d startups",
905 listener_proctitle, children_active,
906 options.max_startups_begin, options.max_startups);
907 oactive = children_active;
908 }
909 if (received_sighup) {
910 if (!lameduck) {
911 debug("Received SIGHUP; waiting for children");
912 close_listen_socks();
913 lameduck = 1;
914 }
915 if (listening <= 0) {
916 sigprocmask(SIG_SETMASK, &osigset, NULL);
917 sighup_restart();
918 }
919 }
920
921 for (i = 0; i < num_listen_socks; i++) {
922 pfd[i].fd = listen_socks[i];
923 pfd[i].events = POLLIN;
924 }
925 npfd = num_listen_socks;
926 for (i = 0; i < options.max_startups; i++) {
927 startup_pollfd[i] = -1;
928 if (children[i].pipefd != -1) {
929 pfd[npfd].fd = children[i].pipefd;
930 pfd[npfd].events = POLLIN;
931 startup_pollfd[i] = npfd++;
932 }
933 }
934
935 /* Wait until a connection arrives or a child exits. */
936 ret = ppoll(pfd, npfd, NULL, &osigset);
937 if (ret == -1 && errno != EINTR) {
938 error("ppoll: %.100s", strerror(errno));
939 if (errno == EINVAL)
940 cleanup_exit(1); /* can't recover */
941 }
942 sigprocmask(SIG_SETMASK, &osigset, NULL);
943 if (ret == -1)
944 continue;
945
946 for (i = 0; i < options.max_startups; i++) {
947 if (children[i].pipefd == -1 ||
948 startup_pollfd[i] == -1 ||
949 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP)))
950 continue;
951 switch (read(children[i].pipefd, &c, sizeof(c))) {
952 case -1:
953 if (errno == EINTR || errno == EAGAIN)
954 continue;
955 if (errno != EPIPE) {
956 error_f("startup pipe %d (fd=%d): "
957 "read %s", i, children[i].pipefd,
958 strerror(errno));
959 }
960 /* FALLTHROUGH */
961 case 0:
962 /* child exited preauth */
963 if (children[i].early)
964 listening--;
965 srclimit_done(children[i].pipefd);
966 child_close(&(children[i]), 0, 0);
967 break;
968 case 1:
969 if (children[i].early && c == '\0') {
970 /* child has finished preliminaries */
971 listening--;
972 children[i].early = 0;
973 debug2_f("child %lu for %s received "
974 "config", (long)children[i].pid,
975 children[i].id);
976 } else if (!children[i].early && c == '\001') {
977 /* child has completed auth */
978 debug2_f("child %lu for %s auth done",
979 (long)children[i].pid,
980 children[i].id);
981 child_close(&(children[i]), 1, 0);
982 } else {
983 error_f("unexpected message 0x%02x "
984 "child %ld for %s in state %d",
985 (int)c, (long)children[i].pid,
986 children[i].id, children[i].early);
987 }
988 break;
989 }
990 }
991 for (i = 0; i < num_listen_socks; i++) {
992 if (!(pfd[i].revents & POLLIN))
993 continue;
994 fromlen = sizeof(from);
995 *newsock = accept(listen_socks[i],
996 (struct sockaddr *)&from, &fromlen);
997 if (*newsock == -1) {
998 if (errno != EINTR && errno != EWOULDBLOCK &&
999 errno != ECONNABORTED && errno != EAGAIN)
1000 error("accept: %.100s",
1001 strerror(errno));
1002 if (errno == EMFILE || errno == ENFILE)
1003 usleep(100 * 1000);
1004 continue;
1005 }
1006 if (unset_nonblock(*newsock) == -1) {
1007 close(*newsock);
1008 continue;
1009 }
1010 if (pipe(startup_p) == -1) {
1011 error_f("pipe(startup_p): %s", strerror(errno));
1012 close(*newsock);
1013 continue;
1014 }
1015 if (drop_connection(*newsock,
1016 children_active, startup_p[0])) {
1017 close(*newsock);
1018 close(startup_p[0]);
1019 close(startup_p[1]);
1020 continue;
1021 }
1022
1023 if (socketpair(AF_UNIX,
1024 SOCK_STREAM, 0, config_s) == -1) {
1025 error("reexec socketpair: %s",
1026 strerror(errno));
1027 close(*newsock);
1028 close(startup_p[0]);
1029 close(startup_p[1]);
1030 continue;
1031 }
1032
1033 /*
1034 * Got connection. Fork a child to handle it, unless
1035 * we are in debugging mode.
1036 */
1037 if (debug_flag) {
1038 /*
1039 * In debugging mode. Close the listening
1040 * socket, and start processing the
1041 * connection without forking.
1042 */
1043 debug("Server will not fork when running in debugging mode.");
1044 close_listen_socks();
1045 *sock_in = *newsock;
1046 *sock_out = *newsock;
1047 close(startup_p[0]);
1048 close(startup_p[1]);
1049 startup_pipe = -1;
1050 send_rexec_state(config_s[0], cfg);
1051 close(config_s[0]);
1052 free(pfd);
1053 return;
1054 }
1055
1056 /*
1057 * Normal production daemon. Fork, and have
1058 * the child process the connection. The
1059 * parent continues listening.
1060 */
1061 platform_pre_fork();
1062 listening++;
1063 child = child_register(startup_p[0], *newsock);
1064 if ((child->pid = fork()) == 0) {
1065 /*
1066 * Child. Close the listening and
1067 * max_startup sockets. Start using
1068 * the accepted socket. Reinitialize
1069 * logging (since our pid has changed).
1070 * We return from this function to handle
1071 * the connection.
1072 */
1073 platform_post_fork_child();
1074 startup_pipe = startup_p[1];
1075 close_startup_pipes();
1076 close_listen_socks();
1077 *sock_in = *newsock;
1078 *sock_out = *newsock;
1079 log_init(__progname,
1080 options.log_level,
1081 options.log_facility,
1082 log_stderr);
1083 close(config_s[0]);
1084 free(pfd);
1085 return;
1086 }
1087
1088 /* Parent. Stay in the loop. */
1089 platform_post_fork_parent(child->pid);
1090 if (child->pid == -1)
1091 error("fork: %.100s", strerror(errno));
1092 else
1093 debug("Forked child %ld.", (long)child->pid);
1094
1095 close(startup_p[1]);
1096
1097 close(config_s[1]);
1098 send_rexec_state(config_s[0], cfg);
1099 close(config_s[0]);
1100 close(*newsock);
1101
1102 /*
1103 * Ensure that our random state differs
1104 * from that of the child
1105 */
1106 arc4random_stir();
1107 arc4random_buf(rnd, sizeof(rnd));
1108 #ifdef WITH_OPENSSL
1109 RAND_seed(rnd, sizeof(rnd));
1110 if ((RAND_bytes((u_char *)rnd, 1)) != 1)
1111 fatal("%s: RAND_bytes failed", __func__);
1112 #endif
1113 explicit_bzero(rnd, sizeof(rnd));
1114 }
1115 }
1116 }
1117
1118 static void
accumulate_host_timing_secret(struct sshbuf * server_cfg,struct sshkey * key)1119 accumulate_host_timing_secret(struct sshbuf *server_cfg,
1120 struct sshkey *key)
1121 {
1122 static struct ssh_digest_ctx *ctx;
1123 u_char *hash;
1124 size_t len;
1125 struct sshbuf *buf;
1126 int r;
1127
1128 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL)
1129 fatal_f("ssh_digest_start");
1130 if (key == NULL) { /* finalize */
1131 /* add server config in case we are using agent for host keys */
1132 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg),
1133 sshbuf_len(server_cfg)) != 0)
1134 fatal_f("ssh_digest_update");
1135 len = ssh_digest_bytes(SSH_DIGEST_SHA512);
1136 hash = xmalloc(len);
1137 if (ssh_digest_final(ctx, hash, len) != 0)
1138 fatal_f("ssh_digest_final");
1139 options.timing_secret = PEEK_U64(hash);
1140 freezero(hash, len);
1141 ssh_digest_free(ctx);
1142 ctx = NULL;
1143 return;
1144 }
1145 if ((buf = sshbuf_new()) == NULL)
1146 fatal_f("could not allocate buffer");
1147 if ((r = sshkey_private_serialize(key, buf)) != 0)
1148 fatal_fr(r, "encode %s key", sshkey_ssh_name(key));
1149 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0)
1150 fatal_f("ssh_digest_update");
1151 sshbuf_reset(buf);
1152 sshbuf_free(buf);
1153 }
1154
1155 static char *
prepare_proctitle(int ac,char ** av)1156 prepare_proctitle(int ac, char **av)
1157 {
1158 char *ret = NULL;
1159 int i;
1160
1161 for (i = 0; i < ac; i++)
1162 xextendf(&ret, " ", "%s", av[i]);
1163 return ret;
1164 }
1165
1166 static void
print_config(struct connection_info * connection_info)1167 print_config(struct connection_info *connection_info)
1168 {
1169 connection_info->test = 1;
1170 parse_server_match_config(&options, &includes, connection_info);
1171 dump_config(&options);
1172 exit(0);
1173 }
1174
1175 /*
1176 * Main program for the daemon.
1177 */
1178 int
main(int ac,char ** av)1179 main(int ac, char **av)
1180 {
1181 extern char *optarg;
1182 extern int optind;
1183 int log_stderr = 0, inetd_flag = 0, test_flag = 0, no_daemon_flag = 0;
1184 char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1185 int r, opt, do_dump_cfg = 0, keytype, already_daemon, have_agent = 0;
1186 int sock_in = -1, sock_out = -1, newsock = -1, rexec_argc = 0;
1187 int devnull, config_s[2] = { -1 , -1 }, have_connection_info = 0;
1188 int need_chroot = 1;
1189 char *fp, *line, *logfile = NULL, **rexec_argv = NULL;
1190 struct stat sb;
1191 u_int i, j;
1192 mode_t new_umask;
1193 struct sshkey *key;
1194 struct sshkey *pubkey;
1195 struct connection_info connection_info;
1196 sigset_t sigmask;
1197
1198 memset(&connection_info, 0, sizeof(connection_info));
1199 #ifdef HAVE_SECUREWARE
1200 (void)set_auth_parameters(ac, av);
1201 #endif
1202 __progname = ssh_get_progname(av[0]);
1203
1204 sigemptyset(&sigmask);
1205 sigprocmask(SIG_SETMASK, &sigmask, NULL);
1206
1207 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */
1208 saved_argc = ac;
1209 rexec_argc = ac;
1210 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv));
1211 for (i = 0; (int)i < ac; i++)
1212 saved_argv[i] = xstrdup(av[i]);
1213 saved_argv[i] = NULL;
1214
1215 #ifndef HAVE_SETPROCTITLE
1216 /* Prepare for later setproctitle emulation */
1217 compat_init_setproctitle(ac, av);
1218 av = saved_argv;
1219 #endif
1220
1221 if (geteuid() == 0 && setgroups(0, NULL) == -1)
1222 debug("setgroups(): %.200s", strerror(errno));
1223
1224 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1225 sanitise_stdfd();
1226
1227 /* Initialize configuration options to their default values. */
1228 initialize_server_options(&options);
1229
1230 /* Parse command-line arguments. */
1231 while ((opt = getopt(ac, av,
1232 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) {
1233 switch (opt) {
1234 case '4':
1235 options.address_family = AF_INET;
1236 break;
1237 case '6':
1238 options.address_family = AF_INET6;
1239 break;
1240 case 'f':
1241 config_file_name = optarg;
1242 break;
1243 case 'c':
1244 servconf_add_hostcert("[command-line]", 0,
1245 &options, optarg);
1246 break;
1247 case 'd':
1248 if (debug_flag == 0) {
1249 debug_flag = 1;
1250 options.log_level = SYSLOG_LEVEL_DEBUG1;
1251 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1252 options.log_level++;
1253 break;
1254 case 'D':
1255 no_daemon_flag = 1;
1256 break;
1257 case 'G':
1258 do_dump_cfg = 1;
1259 break;
1260 case 'E':
1261 logfile = optarg;
1262 /* FALLTHROUGH */
1263 case 'e':
1264 log_stderr = 1;
1265 break;
1266 case 'i':
1267 inetd_flag = 1;
1268 break;
1269 case 'r':
1270 logit("-r option is deprecated");
1271 break;
1272 case 'R':
1273 fatal("-R not supported here");
1274 break;
1275 case 'Q':
1276 /* ignored */
1277 break;
1278 case 'q':
1279 options.log_level = SYSLOG_LEVEL_QUIET;
1280 break;
1281 case 'b':
1282 /* protocol 1, ignored */
1283 break;
1284 case 'p':
1285 options.ports_from_cmdline = 1;
1286 if (options.num_ports >= MAX_PORTS) {
1287 fprintf(stderr, "too many ports.\n");
1288 exit(1);
1289 }
1290 options.ports[options.num_ports++] = a2port(optarg);
1291 if (options.ports[options.num_ports-1] <= 0) {
1292 fprintf(stderr, "Bad port number.\n");
1293 exit(1);
1294 }
1295 break;
1296 case 'g':
1297 if ((options.login_grace_time = convtime(optarg)) == -1) {
1298 fprintf(stderr, "Invalid login grace time.\n");
1299 exit(1);
1300 }
1301 break;
1302 case 'k':
1303 /* protocol 1, ignored */
1304 break;
1305 case 'h':
1306 servconf_add_hostkey("[command-line]", 0,
1307 &options, optarg, 1);
1308 break;
1309 case 't':
1310 test_flag = 1;
1311 break;
1312 case 'T':
1313 test_flag = 2;
1314 break;
1315 case 'C':
1316 if (parse_server_match_testspec(&connection_info,
1317 optarg) == -1)
1318 exit(1);
1319 have_connection_info = 1;
1320 break;
1321 case 'u':
1322 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL);
1323 if (utmp_len > HOST_NAME_MAX+1) {
1324 fprintf(stderr, "Invalid utmp length.\n");
1325 exit(1);
1326 }
1327 break;
1328 case 'o':
1329 line = xstrdup(optarg);
1330 if (process_server_config_line(&options, line,
1331 "command-line", 0, NULL, NULL, &includes) != 0)
1332 exit(1);
1333 free(line);
1334 break;
1335 case 'V':
1336 fprintf(stderr, "%s, %s\n",
1337 SSH_RELEASE, SSH_OPENSSL_VERSION);
1338 exit(0);
1339 default:
1340 usage();
1341 break;
1342 }
1343 }
1344 if (!test_flag && !do_dump_cfg && !path_absolute(av[0]))
1345 fatal("sshd requires execution with an absolute path");
1346
1347 closefrom(STDERR_FILENO + 1);
1348
1349 /* Reserve fds we'll need later for reexec things */
1350 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1)
1351 fatal("open %s: %s", _PATH_DEVNULL, strerror(errno));
1352 while (devnull < REEXEC_MIN_FREE_FD) {
1353 if ((devnull = dup(devnull)) == -1)
1354 fatal("dup %s: %s", _PATH_DEVNULL, strerror(errno));
1355 }
1356
1357 seed_rng();
1358
1359 /* If requested, redirect the logs to the specified logfile. */
1360 if (logfile != NULL) {
1361 char *cp, pid_s[32];
1362
1363 snprintf(pid_s, sizeof(pid_s), "%ld", (unsigned long)getpid());
1364 cp = percent_expand(logfile,
1365 "p", pid_s,
1366 "P", "sshd",
1367 (char *)NULL);
1368 log_redirect_stderr_to(cp);
1369 free(cp);
1370 }
1371
1372 /*
1373 * Force logging to stderr until we have loaded the private host
1374 * key (unless started from inetd)
1375 */
1376 log_init(__progname,
1377 options.log_level == SYSLOG_LEVEL_NOT_SET ?
1378 SYSLOG_LEVEL_INFO : options.log_level,
1379 options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1380 SYSLOG_FACILITY_AUTH : options.log_facility,
1381 log_stderr || !inetd_flag || debug_flag);
1382
1383 /*
1384 * Unset KRB5CCNAME, otherwise the user's session may inherit it from
1385 * root's environment
1386 */
1387 if (getenv("KRB5CCNAME") != NULL)
1388 (void) unsetenv("KRB5CCNAME");
1389
1390 sensitive_data.have_ssh2_key = 0;
1391
1392 /*
1393 * If we're not doing an extended test do not silently ignore connection
1394 * test params.
1395 */
1396 if (test_flag < 2 && have_connection_info)
1397 fatal("Config test connection parameter (-C) provided without "
1398 "test mode (-T)");
1399
1400 /* Fetch our configuration */
1401 if ((cfg = sshbuf_new()) == NULL)
1402 fatal("sshbuf_new config failed");
1403 if (strcasecmp(config_file_name, "none") != 0)
1404 load_server_config(config_file_name, cfg);
1405
1406 parse_server_config(&options, config_file_name, cfg,
1407 &includes, NULL, 0);
1408
1409 /* Fill in default values for those options not explicitly set. */
1410 fill_default_server_options(&options);
1411
1412 /* Check that options are sensible */
1413 if (options.authorized_keys_command_user == NULL &&
1414 (options.authorized_keys_command != NULL &&
1415 strcasecmp(options.authorized_keys_command, "none") != 0))
1416 fatal("AuthorizedKeysCommand set without "
1417 "AuthorizedKeysCommandUser");
1418 if (options.authorized_principals_command_user == NULL &&
1419 (options.authorized_principals_command != NULL &&
1420 strcasecmp(options.authorized_principals_command, "none") != 0))
1421 fatal("AuthorizedPrincipalsCommand set without "
1422 "AuthorizedPrincipalsCommandUser");
1423
1424 /*
1425 * Check whether there is any path through configured auth methods.
1426 * Unfortunately it is not possible to verify this generally before
1427 * daemonisation in the presence of Match blocks, but this catches
1428 * and warns for trivial misconfigurations that could break login.
1429 */
1430 if (options.num_auth_methods != 0) {
1431 for (i = 0; i < options.num_auth_methods; i++) {
1432 if (auth2_methods_valid(options.auth_methods[i],
1433 1) == 0)
1434 break;
1435 }
1436 if (i >= options.num_auth_methods)
1437 fatal("AuthenticationMethods cannot be satisfied by "
1438 "enabled authentication methods");
1439 }
1440
1441 /* Check that there are no remaining arguments. */
1442 if (optind < ac) {
1443 fprintf(stderr, "Extra argument %s.\n", av[optind]);
1444 exit(1);
1445 }
1446
1447 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION);
1448
1449 if (do_dump_cfg)
1450 print_config(&connection_info);
1451
1452 /* load host keys */
1453 sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1454 sizeof(struct sshkey *));
1455 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files,
1456 sizeof(struct sshkey *));
1457
1458 if (options.host_key_agent) {
1459 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME))
1460 setenv(SSH_AUTHSOCKET_ENV_NAME,
1461 options.host_key_agent, 1);
1462 if ((r = ssh_get_authentication_socket(NULL)) == 0)
1463 have_agent = 1;
1464 else
1465 error_r(r, "Could not connect to agent \"%s\"",
1466 options.host_key_agent);
1467 }
1468
1469 for (i = 0; i < options.num_host_key_files; i++) {
1470 int ll = options.host_key_file_userprovided[i] ?
1471 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1;
1472
1473 if (options.host_key_files[i] == NULL)
1474 continue;
1475 if ((r = sshkey_load_private(options.host_key_files[i], "",
1476 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1477 do_log2_r(r, ll, "Unable to load host key \"%s\"",
1478 options.host_key_files[i]);
1479 if (sshkey_is_sk(key) &&
1480 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
1481 debug("host key %s requires user presence, ignoring",
1482 options.host_key_files[i]);
1483 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
1484 }
1485 if (r == 0 && key != NULL &&
1486 (r = sshkey_shield_private(key)) != 0) {
1487 do_log2_r(r, ll, "Unable to shield host key \"%s\"",
1488 options.host_key_files[i]);
1489 sshkey_free(key);
1490 key = NULL;
1491 }
1492 if ((r = sshkey_load_public(options.host_key_files[i],
1493 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR)
1494 do_log2_r(r, ll, "Unable to load host key \"%s\"",
1495 options.host_key_files[i]);
1496 if (pubkey != NULL && key != NULL) {
1497 if (!sshkey_equal(pubkey, key)) {
1498 error("Public key for %s does not match "
1499 "private key", options.host_key_files[i]);
1500 sshkey_free(pubkey);
1501 pubkey = NULL;
1502 }
1503 }
1504 if (pubkey == NULL && key != NULL) {
1505 if ((r = sshkey_from_private(key, &pubkey)) != 0)
1506 fatal_r(r, "Could not demote key: \"%s\"",
1507 options.host_key_files[i]);
1508 }
1509 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey,
1510 options.required_rsa_size)) != 0) {
1511 error_fr(r, "Host key %s", options.host_key_files[i]);
1512 sshkey_free(pubkey);
1513 sshkey_free(key);
1514 continue;
1515 }
1516 sensitive_data.host_keys[i] = key;
1517 sensitive_data.host_pubkeys[i] = pubkey;
1518
1519 if (key == NULL && pubkey != NULL && have_agent) {
1520 debug("will rely on agent for hostkey %s",
1521 options.host_key_files[i]);
1522 keytype = pubkey->type;
1523 } else if (key != NULL) {
1524 keytype = key->type;
1525 accumulate_host_timing_secret(cfg, key);
1526 } else {
1527 do_log2(ll, "Unable to load host key: %s",
1528 options.host_key_files[i]);
1529 sensitive_data.host_keys[i] = NULL;
1530 sensitive_data.host_pubkeys[i] = NULL;
1531 continue;
1532 }
1533
1534 switch (keytype) {
1535 case KEY_RSA:
1536 case KEY_DSA:
1537 case KEY_ECDSA:
1538 case KEY_ED25519:
1539 case KEY_ECDSA_SK:
1540 case KEY_ED25519_SK:
1541 case KEY_XMSS:
1542 if (have_agent || key != NULL)
1543 sensitive_data.have_ssh2_key = 1;
1544 break;
1545 }
1546 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash,
1547 SSH_FP_DEFAULT)) == NULL)
1548 fatal("sshkey_fingerprint failed");
1549 debug("%s host key #%d: %s %s",
1550 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp);
1551 free(fp);
1552 }
1553 accumulate_host_timing_secret(cfg, NULL);
1554 if (!sensitive_data.have_ssh2_key) {
1555 logit("sshd: no hostkeys available -- exiting.");
1556 exit(1);
1557 }
1558
1559 /*
1560 * Load certificates. They are stored in an array at identical
1561 * indices to the public keys that they relate to.
1562 */
1563 sensitive_data.host_certificates = xcalloc(options.num_host_key_files,
1564 sizeof(struct sshkey *));
1565 for (i = 0; i < options.num_host_key_files; i++)
1566 sensitive_data.host_certificates[i] = NULL;
1567
1568 for (i = 0; i < options.num_host_cert_files; i++) {
1569 if (options.host_cert_files[i] == NULL)
1570 continue;
1571 if ((r = sshkey_load_public(options.host_cert_files[i],
1572 &key, NULL)) != 0) {
1573 error_r(r, "Could not load host certificate \"%s\"",
1574 options.host_cert_files[i]);
1575 continue;
1576 }
1577 if (!sshkey_is_cert(key)) {
1578 error("Certificate file is not a certificate: %s",
1579 options.host_cert_files[i]);
1580 sshkey_free(key);
1581 continue;
1582 }
1583 /* Find matching private key */
1584 for (j = 0; j < options.num_host_key_files; j++) {
1585 if (sshkey_equal_public(key,
1586 sensitive_data.host_pubkeys[j])) {
1587 sensitive_data.host_certificates[j] = key;
1588 break;
1589 }
1590 }
1591 if (j >= options.num_host_key_files) {
1592 error("No matching private key for certificate: %s",
1593 options.host_cert_files[i]);
1594 sshkey_free(key);
1595 continue;
1596 }
1597 sensitive_data.host_certificates[j] = key;
1598 debug("host certificate: #%u type %d %s", j, key->type,
1599 sshkey_type(key));
1600 }
1601
1602 /* Ensure privsep directory is correctly configured. */
1603 need_chroot = ((getuid() == 0 || geteuid() == 0) ||
1604 options.kerberos_authentication);
1605 if ((getpwnam(SSH_PRIVSEP_USER)) == NULL && need_chroot) {
1606 fatal("Privilege separation user %s does not exist",
1607 SSH_PRIVSEP_USER);
1608 }
1609 endpwent();
1610
1611 if (need_chroot) {
1612 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &sb) == -1) ||
1613 (S_ISDIR(sb.st_mode) == 0))
1614 fatal("Missing privilege separation directory: %s",
1615 _PATH_PRIVSEP_CHROOT_DIR);
1616 #ifdef HAVE_CYGWIN
1617 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) &&
1618 (sb.st_uid != getuid () ||
1619 (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0))
1620 #else
1621 if (sb.st_uid != 0 || (sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1622 #endif
1623 fatal("%s must be owned by root and not group or "
1624 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1625 }
1626
1627 if (test_flag > 1)
1628 print_config(&connection_info);
1629
1630 /* Configuration looks good, so exit if in test mode. */
1631 if (test_flag)
1632 exit(0);
1633
1634 /*
1635 * Clear out any supplemental groups we may have inherited. This
1636 * prevents inadvertent creation of files with bad modes (in the
1637 * portable version at least, it's certainly possible for PAM
1638 * to create a file, and we can't control the code in every
1639 * module which might be used).
1640 */
1641 if (setgroups(0, NULL) < 0)
1642 debug("setgroups() failed: %.200s", strerror(errno));
1643
1644 /* Prepare arguments for sshd-session */
1645 if (rexec_argc < 0)
1646 fatal("rexec_argc %d < 0", rexec_argc);
1647 rexec_argv = xcalloc(rexec_argc + 3, sizeof(char *));
1648 /* Point to the sshd-session binary instead of sshd */
1649 rexec_argv[0] = options.sshd_session_path;
1650 for (i = 1; i < (u_int)rexec_argc; i++) {
1651 debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1652 rexec_argv[i] = saved_argv[i];
1653 }
1654 rexec_argv[rexec_argc++] = "-R";
1655 rexec_argv[rexec_argc] = NULL;
1656 if (stat(rexec_argv[0], &sb) != 0 || !(sb.st_mode & (S_IXOTH|S_IXUSR)))
1657 fatal("%s does not exist or is not executable", rexec_argv[0]);
1658 debug3("using %s for re-exec", rexec_argv[0]);
1659
1660 listener_proctitle = prepare_proctitle(ac, av);
1661
1662 /* Ensure that umask disallows at least group and world write */
1663 new_umask = umask(0077) | 0022;
1664 (void) umask(new_umask);
1665
1666 /* Initialize the log (it is reinitialized below in case we forked). */
1667 if (debug_flag && !inetd_flag)
1668 log_stderr = 1;
1669 log_init(__progname, options.log_level,
1670 options.log_facility, log_stderr);
1671 for (i = 0; i < options.num_log_verbose; i++)
1672 log_verbose_add(options.log_verbose[i]);
1673
1674 /*
1675 * If not in debugging mode, not started from inetd and not already
1676 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling
1677 * terminal, and fork. The original process exits.
1678 */
1679 already_daemon = daemonized();
1680 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) {
1681
1682 if (daemon(0, 0) == -1)
1683 fatal("daemon() failed: %.200s", strerror(errno));
1684
1685 disconnect_controlling_tty();
1686 }
1687 /* Reinitialize the log (because of the fork above). */
1688 log_init(__progname, options.log_level, options.log_facility, log_stderr);
1689
1690 /*
1691 * Chdir to the root directory so that the current disk can be
1692 * unmounted if desired.
1693 */
1694 if (chdir("/") == -1)
1695 error("chdir(\"/\"): %s", strerror(errno));
1696
1697 /* ignore SIGPIPE */
1698 ssh_signal(SIGPIPE, SIG_IGN);
1699
1700 /* Get a connection, either from inetd or a listening TCP socket */
1701 if (inetd_flag) {
1702 /* Send configuration to ancestor sshd-session process */
1703 if (socketpair(AF_UNIX, SOCK_STREAM, 0, config_s) == -1)
1704 fatal("socketpair: %s", strerror(errno));
1705 send_rexec_state(config_s[0], cfg);
1706 close(config_s[0]);
1707 } else {
1708 platform_pre_listen();
1709 server_listen();
1710
1711 ssh_signal(SIGHUP, sighup_handler);
1712 ssh_signal(SIGCHLD, main_sigchld_handler);
1713 ssh_signal(SIGTERM, sigterm_handler);
1714 ssh_signal(SIGQUIT, sigterm_handler);
1715 #ifdef SIGINFO
1716 ssh_signal(SIGINFO, siginfo_handler);
1717 #endif
1718
1719 platform_post_listen();
1720
1721 /*
1722 * Write out the pid file after the sigterm handler
1723 * is setup and the listen sockets are bound
1724 */
1725 if (options.pid_file != NULL && !debug_flag) {
1726 FILE *f = fopen(options.pid_file, "w");
1727
1728 if (f == NULL) {
1729 error("Couldn't create pid file \"%s\": %s",
1730 options.pid_file, strerror(errno));
1731 } else {
1732 fprintf(f, "%ld\n", (long) getpid());
1733 fclose(f);
1734 }
1735 }
1736
1737 /* Accept a connection and return in a forked child */
1738 server_accept_loop(&sock_in, &sock_out,
1739 &newsock, config_s, log_stderr);
1740 }
1741
1742 /* This is the child processing a new connection. */
1743 setproctitle("%s", "[accepted]");
1744
1745 /*
1746 * Create a new session and process group since the 4.4BSD
1747 * setlogin() affects the entire process group. We don't
1748 * want the child to be able to affect the parent.
1749 */
1750 if (!debug_flag && !inetd_flag && setsid() == -1)
1751 error("setsid: %.100s", strerror(errno));
1752
1753 debug("rexec start in %d out %d newsock %d pipe %d sock %d/%d",
1754 sock_in, sock_out, newsock, startup_pipe, config_s[0], config_s[1]);
1755 if (!inetd_flag) {
1756 if (dup2(newsock, STDIN_FILENO) == -1)
1757 fatal("dup2 stdin: %s", strerror(errno));
1758 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1)
1759 fatal("dup2 stdout: %s", strerror(errno));
1760 if (newsock > STDOUT_FILENO)
1761 close(newsock);
1762 }
1763 if (config_s[1] != REEXEC_CONFIG_PASS_FD) {
1764 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1)
1765 fatal("dup2 config_s: %s", strerror(errno));
1766 close(config_s[1]);
1767 }
1768 if (startup_pipe == -1)
1769 close(REEXEC_STARTUP_PIPE_FD);
1770 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) {
1771 if (dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD) == -1)
1772 fatal("dup2 startup_p: %s", strerror(errno));
1773 close(startup_pipe);
1774 }
1775 log_redirect_stderr_to(NULL);
1776 closefrom(REEXEC_MIN_FREE_FD);
1777
1778 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */
1779 execv(rexec_argv[0], rexec_argv);
1780
1781 fatal("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1782 }
1783
1784 /* server specific fatal cleanup */
1785 void
cleanup_exit(int i)1786 cleanup_exit(int i)
1787 {
1788 _exit(i);
1789 }
1790