xref: /openssh-portable/monitor.c (revision 4ca6a1fa)
1 /* $OpenBSD: monitor.c,v 1.222 2021/01/27 09:26:54 djm Exp $ */
2 /*
3  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
4  * Copyright 2002 Markus Friedl <markus@openbsd.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include "includes.h"
29 
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <sys/wait.h>
33 
34 #include <errno.h>
35 #include <fcntl.h>
36 #include <limits.h>
37 #ifdef HAVE_PATHS_H
38 #include <paths.h>
39 #endif
40 #include <pwd.h>
41 #include <signal.h>
42 #ifdef HAVE_STDINT_H
43 # include <stdint.h>
44 #endif
45 #include <stdlib.h>
46 #include <string.h>
47 #include <stdarg.h>
48 #include <stdio.h>
49 #include <unistd.h>
50 #ifdef HAVE_POLL_H
51 #include <poll.h>
52 #else
53 # ifdef HAVE_SYS_POLL_H
54 #  include <sys/poll.h>
55 # endif
56 #endif
57 
58 #ifdef WITH_OPENSSL
59 #include <openssl/dh.h>
60 #endif
61 
62 #include "openbsd-compat/sys-tree.h"
63 #include "openbsd-compat/sys-queue.h"
64 #include "openbsd-compat/openssl-compat.h"
65 
66 #include "atomicio.h"
67 #include "xmalloc.h"
68 #include "ssh.h"
69 #include "sshkey.h"
70 #include "sshbuf.h"
71 #include "hostfile.h"
72 #include "auth.h"
73 #include "cipher.h"
74 #include "kex.h"
75 #include "dh.h"
76 #include "auth-pam.h"
77 #include "packet.h"
78 #include "auth-options.h"
79 #include "sshpty.h"
80 #include "channels.h"
81 #include "session.h"
82 #include "sshlogin.h"
83 #include "canohost.h"
84 #include "log.h"
85 #include "misc.h"
86 #include "servconf.h"
87 #include "monitor.h"
88 #ifdef GSSAPI
89 #include "ssh-gss.h"
90 #endif
91 #include "monitor_wrap.h"
92 #include "monitor_fdpass.h"
93 #include "compat.h"
94 #include "ssh2.h"
95 #include "authfd.h"
96 #include "match.h"
97 #include "ssherr.h"
98 #include "sk-api.h"
99 
100 #ifdef GSSAPI
101 static Gssctxt *gsscontext = NULL;
102 #endif
103 
104 /* Imports */
105 extern ServerOptions options;
106 extern u_int utmp_len;
107 extern u_char session_id[];
108 extern struct sshbuf *loginmsg;
109 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
110 
111 /* State exported from the child */
112 static struct sshbuf *child_state;
113 
114 /* Functions on the monitor that answer unprivileged requests */
115 
116 int mm_answer_moduli(struct ssh *, int, struct sshbuf *);
117 int mm_answer_sign(struct ssh *, int, struct sshbuf *);
118 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *);
119 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *);
120 int mm_answer_authserv(struct ssh *, int, struct sshbuf *);
121 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *);
122 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *);
123 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *);
124 int mm_answer_skeyquery(struct ssh *, int, struct sshbuf *);
125 int mm_answer_skeyrespond(struct ssh *, int, struct sshbuf *);
126 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *);
127 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
128 int mm_answer_pty(struct ssh *, int, struct sshbuf *);
129 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
130 int mm_answer_term(struct ssh *, int, struct sshbuf *);
131 int mm_answer_rsa_keyallowed(struct ssh *, int, struct sshbuf *);
132 int mm_answer_rsa_challenge(struct ssh *, int, struct sshbuf *);
133 int mm_answer_rsa_response(struct ssh *, int, struct sshbuf *);
134 int mm_answer_sesskey(struct ssh *, int, struct sshbuf *);
135 int mm_answer_sessid(struct ssh *, int, struct sshbuf *);
136 
137 #ifdef USE_PAM
138 int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
139 int mm_answer_pam_account(struct ssh *, int, struct sshbuf *);
140 int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *);
141 int mm_answer_pam_query(struct ssh *, int, struct sshbuf *);
142 int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *);
143 int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *);
144 #endif
145 
146 #ifdef GSSAPI
147 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
148 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
149 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
150 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
151 #endif
152 
153 #ifdef SSH_AUDIT_EVENTS
154 int mm_answer_audit_event(struct ssh *, int, struct sshbuf *);
155 int mm_answer_audit_command(struct ssh *, int, struct sshbuf *);
156 #endif
157 
158 static Authctxt *authctxt;
159 
160 /* local state for key verify */
161 static u_char *key_blob = NULL;
162 static size_t key_bloblen = 0;
163 static int key_blobtype = MM_NOKEY;
164 static struct sshauthopt *key_opts = NULL;
165 static char *hostbased_cuser = NULL;
166 static char *hostbased_chost = NULL;
167 static char *auth_method = "unknown";
168 static char *auth_submethod = NULL;
169 static u_int session_id2_len = 0;
170 static u_char *session_id2 = NULL;
171 static pid_t monitor_child_pid;
172 
173 struct mon_table {
174 	enum monitor_reqtype type;
175 	int flags;
176 	int (*f)(struct ssh *, int, struct sshbuf *);
177 };
178 
179 #define MON_ISAUTH	0x0004	/* Required for Authentication */
180 #define MON_AUTHDECIDE	0x0008	/* Decides Authentication */
181 #define MON_ONCE	0x0010	/* Disable after calling */
182 #define MON_ALOG	0x0020	/* Log auth attempt without authenticating */
183 
184 #define MON_AUTH	(MON_ISAUTH|MON_AUTHDECIDE)
185 
186 #define MON_PERMIT	0x1000	/* Request is permitted */
187 
188 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
189     struct mon_table **);
190 static int monitor_read_log(struct monitor *);
191 
192 struct mon_table mon_dispatch_proto20[] = {
193 #ifdef WITH_OPENSSL
194     {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
195 #endif
196     {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
197     {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
198     {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
199     {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
200     {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
201 #ifdef USE_PAM
202     {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
203     {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
204     {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx},
205     {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query},
206     {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond},
207     {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
208 #endif
209 #ifdef SSH_AUDIT_EVENTS
210     {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
211 #endif
212 #ifdef BSD_AUTH
213     {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
214     {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
215 #endif
216     {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
217     {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
218 #ifdef GSSAPI
219     {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
220     {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
221     {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
222     {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
223 #endif
224     {0, 0, NULL}
225 };
226 
227 struct mon_table mon_dispatch_postauth20[] = {
228 #ifdef WITH_OPENSSL
229     {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
230 #endif
231     {MONITOR_REQ_SIGN, 0, mm_answer_sign},
232     {MONITOR_REQ_PTY, 0, mm_answer_pty},
233     {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
234     {MONITOR_REQ_TERM, 0, mm_answer_term},
235 #ifdef SSH_AUDIT_EVENTS
236     {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
237     {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
238 #endif
239     {0, 0, NULL}
240 };
241 
242 struct mon_table *mon_dispatch;
243 
244 /* Specifies if a certain message is allowed at the moment */
245 static void
246 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
247 {
248 	while (ent->f != NULL) {
249 		if (ent->type == type) {
250 			ent->flags &= ~MON_PERMIT;
251 			ent->flags |= permit ? MON_PERMIT : 0;
252 			return;
253 		}
254 		ent++;
255 	}
256 }
257 
258 static void
259 monitor_permit_authentications(int permit)
260 {
261 	struct mon_table *ent = mon_dispatch;
262 
263 	while (ent->f != NULL) {
264 		if (ent->flags & MON_AUTH) {
265 			ent->flags &= ~MON_PERMIT;
266 			ent->flags |= permit ? MON_PERMIT : 0;
267 		}
268 		ent++;
269 	}
270 }
271 
272 void
273 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
274 {
275 	struct mon_table *ent;
276 	int authenticated = 0, partial = 0;
277 
278 	debug3("preauth child monitor started");
279 
280 	if (pmonitor->m_recvfd >= 0)
281 		close(pmonitor->m_recvfd);
282 	if (pmonitor->m_log_sendfd >= 0)
283 		close(pmonitor->m_log_sendfd);
284 	pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
285 
286 	authctxt = (Authctxt *)ssh->authctxt;
287 	memset(authctxt, 0, sizeof(*authctxt));
288 	ssh->authctxt = authctxt;
289 
290 	authctxt->loginmsg = loginmsg;
291 
292 	mon_dispatch = mon_dispatch_proto20;
293 	/* Permit requests for moduli and signatures */
294 	monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
295 	monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
296 
297 	/* The first few requests do not require asynchronous access */
298 	while (!authenticated) {
299 		partial = 0;
300 		auth_method = "unknown";
301 		auth_submethod = NULL;
302 		auth2_authctxt_reset_info(authctxt);
303 
304 		authenticated = (monitor_read(ssh, pmonitor,
305 		    mon_dispatch, &ent) == 1);
306 
307 		/* Special handling for multiple required authentications */
308 		if (options.num_auth_methods != 0) {
309 			if (authenticated &&
310 			    !auth2_update_methods_lists(authctxt,
311 			    auth_method, auth_submethod)) {
312 				debug3_f("method %s: partial", auth_method);
313 				authenticated = 0;
314 				partial = 1;
315 			}
316 		}
317 
318 		if (authenticated) {
319 			if (!(ent->flags & MON_AUTHDECIDE))
320 				fatal_f("unexpected authentication from %d",
321 				    ent->type);
322 			if (authctxt->pw->pw_uid == 0 &&
323 			    !auth_root_allowed(ssh, auth_method))
324 				authenticated = 0;
325 #ifdef USE_PAM
326 			/* PAM needs to perform account checks after auth */
327 			if (options.use_pam && authenticated) {
328 				struct sshbuf *m;
329 
330 				if ((m = sshbuf_new()) == NULL)
331 					fatal("%s: sshbuf_new failed",
332 					    __func__);
333 				mm_request_receive_expect(pmonitor->m_sendfd,
334 				    MONITOR_REQ_PAM_ACCOUNT, m);
335 				authenticated = mm_answer_pam_account(
336 				    ssh, pmonitor->m_sendfd, m);
337 				sshbuf_free(m);
338 			}
339 #endif
340 		}
341 		if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
342 			auth_log(ssh, authenticated, partial,
343 			    auth_method, auth_submethod);
344 			if (!partial && !authenticated)
345 				authctxt->failures++;
346 			if (authenticated || partial) {
347 				auth2_update_session_info(authctxt,
348 				    auth_method, auth_submethod);
349 			}
350 		}
351 	}
352 
353 	if (!authctxt->valid)
354 		fatal_f("authenticated invalid user");
355 	if (strcmp(auth_method, "unknown") == 0)
356 		fatal_f("authentication method name unknown");
357 
358 	debug_f("user %s authenticated by privileged process", authctxt->user);
359 	ssh->authctxt = NULL;
360 	ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
361 
362 	mm_get_keystate(ssh, pmonitor);
363 
364 	/* Drain any buffered messages from the child */
365 	while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
366 		;
367 
368 	if (pmonitor->m_recvfd >= 0)
369 		close(pmonitor->m_recvfd);
370 	if (pmonitor->m_log_sendfd >= 0)
371 		close(pmonitor->m_log_sendfd);
372 	pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
373 }
374 
375 static void
376 monitor_set_child_handler(pid_t pid)
377 {
378 	monitor_child_pid = pid;
379 }
380 
381 static void
382 monitor_child_handler(int sig)
383 {
384 	kill(monitor_child_pid, sig);
385 }
386 
387 void
388 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
389 {
390 	close(pmonitor->m_recvfd);
391 	pmonitor->m_recvfd = -1;
392 
393 	monitor_set_child_handler(pmonitor->m_pid);
394 	ssh_signal(SIGHUP, &monitor_child_handler);
395 	ssh_signal(SIGTERM, &monitor_child_handler);
396 	ssh_signal(SIGINT, &monitor_child_handler);
397 #ifdef SIGXFSZ
398 	ssh_signal(SIGXFSZ, SIG_IGN);
399 #endif
400 
401 	mon_dispatch = mon_dispatch_postauth20;
402 
403 	/* Permit requests for moduli and signatures */
404 	monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
405 	monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
406 	monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
407 
408 	if (auth_opts->permit_pty_flag) {
409 		monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
410 		monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
411 	}
412 
413 	for (;;)
414 		monitor_read(ssh, pmonitor, mon_dispatch, NULL);
415 }
416 
417 static int
418 monitor_read_log(struct monitor *pmonitor)
419 {
420 	struct sshbuf *logmsg;
421 	u_int len, level, line;
422 	char *msg, *file, *func;
423 	u_char *p;
424 	int r;
425 
426 	if ((logmsg = sshbuf_new()) == NULL)
427 		fatal_f("sshbuf_new");
428 
429 	/* Read length */
430 	if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
431 		fatal_fr(r, "reserve len");
432 	if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
433 		if (errno == EPIPE) {
434 			sshbuf_free(logmsg);
435 			debug_f("child log fd closed");
436 			close(pmonitor->m_log_recvfd);
437 			pmonitor->m_log_recvfd = -1;
438 			return -1;
439 		}
440 		fatal_f("log fd read: %s", strerror(errno));
441 	}
442 	if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
443 		fatal_fr(r, "parse len");
444 	if (len <= 4 || len > 8192)
445 		fatal_f("invalid log message length %u", len);
446 
447 	/* Read severity, message */
448 	sshbuf_reset(logmsg);
449 	if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
450 		fatal_fr(r, "reserve msg");
451 	if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
452 		fatal_f("log fd read: %s", strerror(errno));
453 	if ((r = sshbuf_get_cstring(logmsg, &file, NULL)) != 0 ||
454 	    (r = sshbuf_get_cstring(logmsg, &func, NULL)) != 0 ||
455 	    (r = sshbuf_get_u32(logmsg, &line)) != 0 ||
456 	    (r = sshbuf_get_u32(logmsg, &level)) != 0 ||
457 	    (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
458 		fatal_fr(r, "parse");
459 
460 	/* Log it */
461 	if (log_level_name(level) == NULL)
462 		fatal_f("invalid log level %u (corrupted message?)", level);
463 	sshlog(file, func, line, 0, level, NULL, "%s [preauth]", msg);
464 
465 	sshbuf_free(logmsg);
466 	free(file);
467 	free(func);
468 	free(msg);
469 
470 	return 0;
471 }
472 
473 static int
474 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent,
475     struct mon_table **pent)
476 {
477 	struct sshbuf *m;
478 	int r, ret;
479 	u_char type;
480 	struct pollfd pfd[2];
481 
482 	for (;;) {
483 		memset(&pfd, 0, sizeof(pfd));
484 		pfd[0].fd = pmonitor->m_sendfd;
485 		pfd[0].events = POLLIN;
486 		pfd[1].fd = pmonitor->m_log_recvfd;
487 		pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
488 		if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
489 			if (errno == EINTR || errno == EAGAIN)
490 				continue;
491 			fatal_f("poll: %s", strerror(errno));
492 		}
493 		if (pfd[1].revents) {
494 			/*
495 			 * Drain all log messages before processing next
496 			 * monitor request.
497 			 */
498 			monitor_read_log(pmonitor);
499 			continue;
500 		}
501 		if (pfd[0].revents)
502 			break;  /* Continues below */
503 	}
504 
505 	if ((m = sshbuf_new()) == NULL)
506 		fatal_f("sshbuf_new");
507 
508 	mm_request_receive(pmonitor->m_sendfd, m);
509 	if ((r = sshbuf_get_u8(m, &type)) != 0)
510 		fatal_fr(r, "parse type");
511 
512 	debug3_f("checking request %d", type);
513 
514 	while (ent->f != NULL) {
515 		if (ent->type == type)
516 			break;
517 		ent++;
518 	}
519 
520 	if (ent->f != NULL) {
521 		if (!(ent->flags & MON_PERMIT))
522 			fatal_f("unpermitted request %d", type);
523 		ret = (*ent->f)(ssh, pmonitor->m_sendfd, m);
524 		sshbuf_free(m);
525 
526 		/* The child may use this request only once, disable it */
527 		if (ent->flags & MON_ONCE) {
528 			debug2_f("%d used once, disabling now", type);
529 			ent->flags &= ~MON_PERMIT;
530 		}
531 
532 		if (pent != NULL)
533 			*pent = ent;
534 
535 		return ret;
536 	}
537 
538 	fatal_f("unsupported request: %d", type);
539 
540 	/* NOTREACHED */
541 	return (-1);
542 }
543 
544 /* allowed key state */
545 static int
546 monitor_allowed_key(const u_char *blob, u_int bloblen)
547 {
548 	/* make sure key is allowed */
549 	if (key_blob == NULL || key_bloblen != bloblen ||
550 	    timingsafe_bcmp(key_blob, blob, key_bloblen))
551 		return (0);
552 	return (1);
553 }
554 
555 static void
556 monitor_reset_key_state(void)
557 {
558 	/* reset state */
559 	free(key_blob);
560 	free(hostbased_cuser);
561 	free(hostbased_chost);
562 	sshauthopt_free(key_opts);
563 	key_blob = NULL;
564 	key_bloblen = 0;
565 	key_blobtype = MM_NOKEY;
566 	key_opts = NULL;
567 	hostbased_cuser = NULL;
568 	hostbased_chost = NULL;
569 }
570 
571 #ifdef WITH_OPENSSL
572 int
573 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
574 {
575 	DH *dh;
576 	const BIGNUM *dh_p, *dh_g;
577 	int r;
578 	u_int min, want, max;
579 
580 	if ((r = sshbuf_get_u32(m, &min)) != 0 ||
581 	    (r = sshbuf_get_u32(m, &want)) != 0 ||
582 	    (r = sshbuf_get_u32(m, &max)) != 0)
583 		fatal_fr(r, "parse");
584 
585 	debug3_f("got parameters: %d %d %d", min, want, max);
586 	/* We need to check here, too, in case the child got corrupted */
587 	if (max < min || want < min || max < want)
588 		fatal_f("bad parameters: %d %d %d", min, want, max);
589 
590 	sshbuf_reset(m);
591 
592 	dh = choose_dh(min, want, max);
593 	if (dh == NULL) {
594 		if ((r = sshbuf_put_u8(m, 0)) != 0)
595 			fatal_fr(r, "assemble empty");
596 		return (0);
597 	} else {
598 		/* Send first bignum */
599 		DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
600 		if ((r = sshbuf_put_u8(m, 1)) != 0 ||
601 		    (r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
602 		    (r = sshbuf_put_bignum2(m, dh_g)) != 0)
603 			fatal_fr(r, "assemble");
604 
605 		DH_free(dh);
606 	}
607 	mm_request_send(sock, MONITOR_ANS_MODULI, m);
608 	return (0);
609 }
610 #endif
611 
612 int
613 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
614 {
615 	extern int auth_sock;			/* XXX move to state struct? */
616 	struct sshkey *key;
617 	struct sshbuf *sigbuf = NULL;
618 	u_char *p = NULL, *signature = NULL;
619 	char *alg = NULL;
620 	size_t datlen, siglen, alglen;
621 	int r, is_proof = 0;
622 	u_int keyid, compat;
623 	const char proof_req[] = "hostkeys-prove-00@openssh.com";
624 
625 	debug3_f("entering");
626 
627 	if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
628 	    (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
629 	    (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
630 	    (r = sshbuf_get_u32(m, &compat)) != 0)
631 		fatal_fr(r, "parse");
632 	if (keyid > INT_MAX)
633 		fatal_f("invalid key ID");
634 
635 	/*
636 	 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
637 	 * SHA384 (48 bytes) and SHA512 (64 bytes).
638 	 *
639 	 * Otherwise, verify the signature request is for a hostkey
640 	 * proof.
641 	 *
642 	 * XXX perform similar check for KEX signature requests too?
643 	 * it's not trivial, since what is signed is the hash, rather
644 	 * than the full kex structure...
645 	 */
646 	if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
647 		/*
648 		 * Construct expected hostkey proof and compare it to what
649 		 * the client sent us.
650 		 */
651 		if (session_id2_len == 0) /* hostkeys is never first */
652 			fatal_f("bad data length: %zu", datlen);
653 		if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
654 			fatal_f("no hostkey for index %d", keyid);
655 		if ((sigbuf = sshbuf_new()) == NULL)
656 			fatal_f("sshbuf_new");
657 		if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
658 		    (r = sshbuf_put_string(sigbuf, session_id2,
659 		    session_id2_len)) != 0 ||
660 		    (r = sshkey_puts(key, sigbuf)) != 0)
661 			fatal_fr(r, "assemble private key proof");
662 		if (datlen != sshbuf_len(sigbuf) ||
663 		    memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
664 			fatal_f("bad data length: %zu, hostkey proof len %zu",
665 			    datlen, sshbuf_len(sigbuf));
666 		sshbuf_free(sigbuf);
667 		is_proof = 1;
668 	}
669 
670 	/* save session id, it will be passed on the first call */
671 	if (session_id2_len == 0) {
672 		session_id2_len = datlen;
673 		session_id2 = xmalloc(session_id2_len);
674 		memcpy(session_id2, p, session_id2_len);
675 	}
676 
677 	if ((key = get_hostkey_by_index(keyid)) != NULL) {
678 		if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
679 		    options.sk_provider, NULL, compat)) != 0)
680 			fatal_fr(r, "sign");
681 	} else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
682 	    auth_sock > 0) {
683 		if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
684 		    p, datlen, alg, compat)) != 0)
685 			fatal_fr(r, "agent sign");
686 	} else
687 		fatal_f("no hostkey from index %d", keyid);
688 
689 	debug3_f("%s signature %p(%zu)", is_proof ? "hostkey proof" : "KEX",
690 	    signature, siglen);
691 
692 	sshbuf_reset(m);
693 	if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
694 		fatal_fr(r, "assemble");
695 
696 	free(alg);
697 	free(p);
698 	free(signature);
699 
700 	mm_request_send(sock, MONITOR_ANS_SIGN, m);
701 
702 	/* Turn on permissions for getpwnam */
703 	monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
704 
705 	return (0);
706 }
707 
708 #define PUTPW(b, id) \
709 	do { \
710 		if ((r = sshbuf_put_string(b, \
711 		    &pwent->id, sizeof(pwent->id))) != 0) \
712 			fatal_fr(r, "assemble %s", #id); \
713 	} while (0)
714 
715 /* Retrieves the password entry and also checks if the user is permitted */
716 int
717 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
718 {
719 	char *username;
720 	struct passwd *pwent;
721 	int r, allowed = 0;
722 	u_int i;
723 
724 	debug3_f("entering");
725 
726 	if (authctxt->attempt++ != 0)
727 		fatal_f("multiple attempts for getpwnam");
728 
729 	if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0)
730 		fatal_fr(r, "parse");
731 
732 	pwent = getpwnamallow(ssh, username);
733 
734 	authctxt->user = xstrdup(username);
735 	setproctitle("%s [priv]", pwent ? username : "unknown");
736 	free(username);
737 
738 	sshbuf_reset(m);
739 
740 	if (pwent == NULL) {
741 		if ((r = sshbuf_put_u8(m, 0)) != 0)
742 			fatal_fr(r, "assemble fakepw");
743 		authctxt->pw = fakepw();
744 		goto out;
745 	}
746 
747 	allowed = 1;
748 	authctxt->pw = pwent;
749 	authctxt->valid = 1;
750 
751 	/* XXX send fake class/dir/shell, etc. */
752 	if ((r = sshbuf_put_u8(m, 1)) != 0)
753 		fatal_fr(r, "assemble ok");
754 	PUTPW(m, pw_uid);
755 	PUTPW(m, pw_gid);
756 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
757 	PUTPW(m, pw_change);
758 #endif
759 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
760 	PUTPW(m, pw_expire);
761 #endif
762 	if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
763 	    (r = sshbuf_put_cstring(m, "*")) != 0 ||
764 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
765 	    (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
766 #endif
767 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
768 	    (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
769 #endif
770 	    (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
771 	    (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
772 		fatal_fr(r, "assemble pw");
773 
774  out:
775 	ssh_packet_set_log_preamble(ssh, "%suser %s",
776 	    authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
777 	if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0)
778 		fatal_fr(r, "assemble options");
779 
780 #define M_CP_STROPT(x) do { \
781 		if (options.x != NULL && \
782 		    (r = sshbuf_put_cstring(m, options.x)) != 0) \
783 			fatal_fr(r, "assemble %s", #x); \
784 	} while (0)
785 #define M_CP_STRARRAYOPT(x, nx) do { \
786 		for (i = 0; i < options.nx; i++) { \
787 			if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \
788 				fatal_fr(r, "assemble %s", #x); \
789 		} \
790 	} while (0)
791 	/* See comment in servconf.h */
792 	COPY_MATCH_STRING_OPTS();
793 #undef M_CP_STROPT
794 #undef M_CP_STRARRAYOPT
795 
796 	/* Create valid auth method lists */
797 	if (auth2_setup_methods_lists(authctxt) != 0) {
798 		/*
799 		 * The monitor will continue long enough to let the child
800 		 * run to it's packet_disconnect(), but it must not allow any
801 		 * authentication to succeed.
802 		 */
803 		debug_f("no valid authentication method lists");
804 	}
805 
806 	debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed);
807 	mm_request_send(sock, MONITOR_ANS_PWNAM, m);
808 
809 	/* Allow service/style information on the auth context */
810 	monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
811 	monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
812 
813 #ifdef USE_PAM
814 	if (options.use_pam)
815 		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
816 #endif
817 
818 	return (0);
819 }
820 
821 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m)
822 {
823 	char *banner;
824 	int r;
825 
826 	sshbuf_reset(m);
827 	banner = auth2_read_banner();
828 	if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
829 		fatal_fr(r, "assemble");
830 	mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
831 	free(banner);
832 
833 	return (0);
834 }
835 
836 int
837 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m)
838 {
839 	int r;
840 
841 	monitor_permit_authentications(1);
842 
843 	if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
844 	    (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
845 		fatal_fr(r, "parse");
846 	debug3_f("service=%s, style=%s", authctxt->service, authctxt->style);
847 
848 	if (strlen(authctxt->style) == 0) {
849 		free(authctxt->style);
850 		authctxt->style = NULL;
851 	}
852 
853 	return (0);
854 }
855 
856 /*
857  * Check that the key type appears in the supplied pattern list, ignoring
858  * mismatches in the signature algorithm. (Signature algorithm checks are
859  * performed in the unprivileged authentication code).
860  * Returns 1 on success, 0 otherwise.
861  */
862 static int
863 key_base_type_match(const char *method, const struct sshkey *key,
864     const char *list)
865 {
866 	char *s, *l, *ol = xstrdup(list);
867 	int found = 0;
868 
869 	l = ol;
870 	for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
871 		if (sshkey_type_from_name(s) == key->type) {
872 			found = 1;
873 			break;
874 		}
875 	}
876 	if (!found) {
877 		error("%s key type %s is not in permitted list %s", method,
878 		    sshkey_ssh_name(key), list);
879 	}
880 
881 	free(ol);
882 	return found;
883 }
884 
885 int
886 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m)
887 {
888 	static int call_count;
889 	char *passwd;
890 	int r, authenticated;
891 	size_t plen;
892 
893 	if (!options.password_authentication)
894 		fatal_f("password authentication not enabled");
895 	if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
896 		fatal_fr(r, "parse");
897 	/* Only authenticate if the context is valid */
898 	authenticated = options.password_authentication &&
899 	    auth_password(ssh, passwd);
900 	freezero(passwd, plen);
901 
902 	sshbuf_reset(m);
903 	if ((r = sshbuf_put_u32(m, authenticated)) != 0)
904 		fatal_fr(r, "assemble");
905 #ifdef USE_PAM
906 	if ((r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0)
907 		fatal_fr(r, "assemble PAM");
908 #endif
909 
910 	debug3("%s: sending result %d", __func__, authenticated);
911 	debug3_f("sending result %d", authenticated);
912 	mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m);
913 
914 	call_count++;
915 	if (plen == 0 && call_count == 1)
916 		auth_method = "none";
917 	else
918 		auth_method = "password";
919 
920 	/* Causes monitor loop to terminate if authenticated */
921 	return (authenticated);
922 }
923 
924 #ifdef BSD_AUTH
925 int
926 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m)
927 {
928 	char *name, *infotxt;
929 	u_int numprompts, *echo_on, success;
930 	char **prompts;
931 	int r;
932 
933 	if (!options.kbd_interactive_authentication)
934 		fatal_f("kbd-int authentication not enabled");
935 	success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
936 	    &prompts, &echo_on) < 0 ? 0 : 1;
937 
938 	sshbuf_reset(m);
939 	if ((r = sshbuf_put_u32(m, success)) != 0)
940 		fatal_fr(r, "assemble");
941 	if (success) {
942 		if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
943 			fatal_fr(r, "assemble prompt");
944 	}
945 
946 	debug3_f("sending challenge success: %u", success);
947 	mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
948 
949 	if (success) {
950 		free(name);
951 		free(infotxt);
952 		free(prompts);
953 		free(echo_on);
954 	}
955 
956 	return (0);
957 }
958 
959 int
960 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m)
961 {
962 	char *response;
963 	int r, authok;
964 
965 	if (!options.kbd_interactive_authentication)
966 		fatal_f("kbd-int authentication not enabled");
967 	if (authctxt->as == NULL)
968 		fatal_f("no bsd auth session");
969 
970 	if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
971 		fatal_fr(r, "parse");
972 	authok = options.challenge_response_authentication &&
973 	    auth_userresponse(authctxt->as, response, 0);
974 	authctxt->as = NULL;
975 	debug3_f("<%s> = <%d>", response, authok);
976 	free(response);
977 
978 	sshbuf_reset(m);
979 	if ((r = sshbuf_put_u32(m, authok)) != 0)
980 		fatal_fr(r, "assemble");
981 
982 	debug3_f("sending authenticated: %d", authok);
983 	mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
984 
985 	auth_method = "keyboard-interactive";
986 	auth_submethod = "bsdauth";
987 
988 	return (authok != 0);
989 }
990 #endif
991 
992 #ifdef USE_PAM
993 int
994 mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m)
995 {
996 	if (!options.use_pam)
997 		fatal("UsePAM not set, but ended up in %s anyway", __func__);
998 
999 	start_pam(ssh);
1000 
1001 	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
1002 	if (options.kbd_interactive_authentication)
1003 		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1004 
1005 	return (0);
1006 }
1007 
1008 int
1009 mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m)
1010 {
1011 	u_int ret;
1012 	int r;
1013 
1014 	if (!options.use_pam)
1015 		fatal("%s: PAM not enabled", __func__);
1016 
1017 	ret = do_pam_account();
1018 
1019 	if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1020 	    (r = sshbuf_put_stringb(m, loginmsg)) != 0)
1021 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1022 
1023 	mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
1024 
1025 	return (ret);
1026 }
1027 
1028 static void *sshpam_ctxt, *sshpam_authok;
1029 extern KbdintDevice sshpam_device;
1030 
1031 int
1032 mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1033 {
1034 	u_int ok = 0;
1035 	int r;
1036 
1037 	debug3("%s", __func__);
1038 	if (!options.kbd_interactive_authentication)
1039 		fatal("%s: kbd-int authentication not enabled", __func__);
1040 	if (sshpam_ctxt != NULL)
1041 		fatal("%s: already called", __func__);
1042 	sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
1043 	sshpam_authok = NULL;
1044 	sshbuf_reset(m);
1045 	if (sshpam_ctxt != NULL) {
1046 		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
1047 		monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
1048 		ok = 1;
1049 	}
1050 	if ((r = sshbuf_put_u32(m, ok)) != 0)
1051 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1052 	mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
1053 	return (0);
1054 }
1055 
1056 int
1057 mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m)
1058 {
1059 	char *name = NULL, *info = NULL, **prompts = NULL;
1060 	u_int i, num = 0, *echo_on = 0;
1061 	int r, ret;
1062 
1063 	debug3("%s", __func__);
1064 	sshpam_authok = NULL;
1065 	if (sshpam_ctxt == NULL)
1066 		fatal("%s: no context", __func__);
1067 	ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
1068 	    &num, &prompts, &echo_on);
1069 	if (ret == 0 && num == 0)
1070 		sshpam_authok = sshpam_ctxt;
1071 	if (num > 1 || name == NULL || info == NULL)
1072 		fatal("sshpam_device.query failed");
1073 	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
1074 	sshbuf_reset(m);
1075 	if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1076 	    (r = sshbuf_put_cstring(m, name)) != 0 ||
1077 	    (r = sshbuf_put_cstring(m, info)) != 0 ||
1078 	    (r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0 ||
1079 	    (r = sshbuf_put_u32(m, num)) != 0)
1080 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1081 	free(name);
1082 	free(info);
1083 	for (i = 0; i < num; ++i) {
1084 		if ((r = sshbuf_put_cstring(m, prompts[i])) != 0 ||
1085 		    (r = sshbuf_put_u32(m, echo_on[i])) != 0)
1086 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
1087 		free(prompts[i]);
1088 	}
1089 	free(prompts);
1090 	free(echo_on);
1091 	auth_method = "keyboard-interactive";
1092 	auth_submethod = "pam";
1093 	mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
1094 	return (0);
1095 }
1096 
1097 int
1098 mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m)
1099 {
1100 	char **resp;
1101 	u_int i, num;
1102 	int r, ret;
1103 
1104 	debug3("%s", __func__);
1105 	if (sshpam_ctxt == NULL)
1106 		fatal("%s: no context", __func__);
1107 	sshpam_authok = NULL;
1108 	if ((r = sshbuf_get_u32(m, &num)) != 0)
1109 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1110 	if (num > 0) {
1111 		resp = xcalloc(num, sizeof(char *));
1112 		for (i = 0; i < num; ++i) {
1113 			if ((r = sshbuf_get_cstring(m, &(resp[i]), NULL)) != 0)
1114 				fatal("%s: buffer error: %s",
1115 				    __func__, ssh_err(r));
1116 		}
1117 		ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
1118 		for (i = 0; i < num; ++i)
1119 			free(resp[i]);
1120 		free(resp);
1121 	} else {
1122 		ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
1123 	}
1124 	sshbuf_reset(m);
1125 	if ((r = sshbuf_put_u32(m, ret)) != 0)
1126 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1127 	mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
1128 	auth_method = "keyboard-interactive";
1129 	auth_submethod = "pam";
1130 	if (ret == 0)
1131 		sshpam_authok = sshpam_ctxt;
1132 	return (0);
1133 }
1134 
1135 int
1136 mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1137 {
1138 	int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
1139 
1140 	debug3("%s", __func__);
1141 	if (sshpam_ctxt == NULL)
1142 		fatal("%s: no context", __func__);
1143 	(sshpam_device.free_ctx)(sshpam_ctxt);
1144 	sshpam_ctxt = sshpam_authok = NULL;
1145 	sshbuf_reset(m);
1146 	mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
1147 	/* Allow another attempt */
1148 	monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1149 	auth_method = "keyboard-interactive";
1150 	auth_submethod = "pam";
1151 	return r;
1152 }
1153 #endif
1154 
1155 int
1156 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m)
1157 {
1158 	struct sshkey *key = NULL;
1159 	char *cuser, *chost;
1160 	u_int pubkey_auth_attempt;
1161 	enum mm_keytype type = 0;
1162 	int r, allowed = 0;
1163 	struct sshauthopt *opts = NULL;
1164 
1165 	debug3_f("entering");
1166 	if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1167 	    (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
1168 	    (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
1169 	    (r = sshkey_froms(m, &key)) != 0 ||
1170 	    (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
1171 		fatal_fr(r, "parse");
1172 
1173 	debug3_f("key_from_blob: %p", key);
1174 
1175 	if (key != NULL && authctxt->valid) {
1176 		/* These should not make it past the privsep child */
1177 		if (sshkey_type_plain(key->type) == KEY_RSA &&
1178 		    (ssh->compat & SSH_BUG_RSASIGMD5) != 0)
1179 			fatal_f("passed a SSH_BUG_RSASIGMD5 key");
1180 
1181 		switch (type) {
1182 		case MM_USERKEY:
1183 			auth_method = "publickey";
1184 			if (!options.pubkey_authentication)
1185 				break;
1186 			if (auth2_key_already_used(authctxt, key))
1187 				break;
1188 			if (!key_base_type_match(auth_method, key,
1189 			    options.pubkey_accepted_algos))
1190 				break;
1191 			allowed = user_key_allowed(ssh, authctxt->pw, key,
1192 			    pubkey_auth_attempt, &opts);
1193 			break;
1194 		case MM_HOSTKEY:
1195 			auth_method = "hostbased";
1196 			if (!options.hostbased_authentication)
1197 				break;
1198 			if (auth2_key_already_used(authctxt, key))
1199 				break;
1200 			if (!key_base_type_match(auth_method, key,
1201 			    options.hostbased_accepted_algos))
1202 				break;
1203 			allowed = hostbased_key_allowed(ssh, authctxt->pw,
1204 			    cuser, chost, key);
1205 			auth2_record_info(authctxt,
1206 			    "client user \"%.100s\", client host \"%.100s\"",
1207 			    cuser, chost);
1208 			break;
1209 		default:
1210 			fatal_f("unknown key type %d", type);
1211 			break;
1212 		}
1213 	}
1214 
1215 	debug3_f("%s authentication%s: %s key is %s", auth_method,
1216 	    pubkey_auth_attempt ? "" : " test",
1217 	    (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
1218 	    allowed ? "allowed" : "not allowed");
1219 
1220 	auth2_record_key(authctxt, 0, key);
1221 
1222 	/* clear temporarily storage (used by verify) */
1223 	monitor_reset_key_state();
1224 
1225 	if (allowed) {
1226 		/* Save temporarily for comparison in verify */
1227 		if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
1228 			fatal_fr(r, "sshkey_to_blob");
1229 		key_blobtype = type;
1230 		key_opts = opts;
1231 		hostbased_cuser = cuser;
1232 		hostbased_chost = chost;
1233 	} else {
1234 		/* Log failed attempt */
1235 		auth_log(ssh, 0, 0, auth_method, NULL);
1236 		free(cuser);
1237 		free(chost);
1238 	}
1239 	sshkey_free(key);
1240 
1241 	sshbuf_reset(m);
1242 	if ((r = sshbuf_put_u32(m, allowed)) != 0)
1243 		fatal_fr(r, "assemble");
1244 	if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
1245 		fatal_fr(r, "sshauthopt_serialise");
1246 	mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
1247 
1248 	if (!allowed)
1249 		sshauthopt_free(opts);
1250 
1251 	return (0);
1252 }
1253 
1254 static int
1255 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen)
1256 {
1257 	struct sshbuf *b;
1258 	const u_char *p;
1259 	char *userstyle, *cp;
1260 	size_t len;
1261 	u_char type;
1262 	int r, fail = 0;
1263 
1264 	if ((b = sshbuf_from(data, datalen)) == NULL)
1265 		fatal_f("sshbuf_from");
1266 
1267 	if (ssh->compat & SSH_OLD_SESSIONID) {
1268 		p = sshbuf_ptr(b);
1269 		len = sshbuf_len(b);
1270 		if ((session_id2 == NULL) ||
1271 		    (len < session_id2_len) ||
1272 		    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1273 			fail++;
1274 		if ((r = sshbuf_consume(b, session_id2_len)) != 0)
1275 			fatal_fr(r, "consume");
1276 	} else {
1277 		if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1278 			fatal_fr(r, "parse sessionid");
1279 		if ((session_id2 == NULL) ||
1280 		    (len != session_id2_len) ||
1281 		    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1282 			fail++;
1283 	}
1284 	if ((r = sshbuf_get_u8(b, &type)) != 0)
1285 		fatal_fr(r, "parse type");
1286 	if (type != SSH2_MSG_USERAUTH_REQUEST)
1287 		fail++;
1288 	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1289 		fatal_fr(r, "parse userstyle");
1290 	xasprintf(&userstyle, "%s%s%s", authctxt->user,
1291 	    authctxt->style ? ":" : "",
1292 	    authctxt->style ? authctxt->style : "");
1293 	if (strcmp(userstyle, cp) != 0) {
1294 		logit("wrong user name passed to monitor: "
1295 		    "expected %s != %.100s", userstyle, cp);
1296 		fail++;
1297 	}
1298 	free(userstyle);
1299 	free(cp);
1300 	if ((r = sshbuf_skip_string(b)) != 0 ||	/* service */
1301 	    (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1302 		fatal_fr(r, "parse method");
1303 	if (strcmp("publickey", cp) != 0)
1304 		fail++;
1305 	free(cp);
1306 	if ((r = sshbuf_get_u8(b, &type)) != 0)
1307 		fatal_fr(r, "parse pktype");
1308 	if (type == 0)
1309 		fail++;
1310 	if ((r = sshbuf_skip_string(b)) != 0 ||	/* pkalg */
1311 	    (r = sshbuf_skip_string(b)) != 0)	/* pkblob */
1312 		fatal_fr(r, "parse pk");
1313 	if (sshbuf_len(b) != 0)
1314 		fail++;
1315 	sshbuf_free(b);
1316 	return (fail == 0);
1317 }
1318 
1319 static int
1320 monitor_valid_hostbasedblob(const u_char *data, u_int datalen,
1321     const char *cuser, const char *chost)
1322 {
1323 	struct sshbuf *b;
1324 	const u_char *p;
1325 	char *cp, *userstyle;
1326 	size_t len;
1327 	int r, fail = 0;
1328 	u_char type;
1329 
1330 	if ((b = sshbuf_from(data, datalen)) == NULL)
1331 		fatal_f("sshbuf_new");
1332 	if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1333 		fatal_fr(r, "parse sessionid");
1334 
1335 	if ((session_id2 == NULL) ||
1336 	    (len != session_id2_len) ||
1337 	    (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1338 		fail++;
1339 
1340 	if ((r = sshbuf_get_u8(b, &type)) != 0)
1341 		fatal_fr(r, "parse type");
1342 	if (type != SSH2_MSG_USERAUTH_REQUEST)
1343 		fail++;
1344 	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1345 		fatal_fr(r, "parse userstyle");
1346 	xasprintf(&userstyle, "%s%s%s", authctxt->user,
1347 	    authctxt->style ? ":" : "",
1348 	    authctxt->style ? authctxt->style : "");
1349 	if (strcmp(userstyle, cp) != 0) {
1350 		logit("wrong user name passed to monitor: "
1351 		    "expected %s != %.100s", userstyle, cp);
1352 		fail++;
1353 	}
1354 	free(userstyle);
1355 	free(cp);
1356 	if ((r = sshbuf_skip_string(b)) != 0 ||	/* service */
1357 	    (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1358 		fatal_fr(r, "parse method");
1359 	if (strcmp(cp, "hostbased") != 0)
1360 		fail++;
1361 	free(cp);
1362 	if ((r = sshbuf_skip_string(b)) != 0 ||	/* pkalg */
1363 	    (r = sshbuf_skip_string(b)) != 0)	/* pkblob */
1364 		fatal_fr(r, "parse pk");
1365 
1366 	/* verify client host, strip trailing dot if necessary */
1367 	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1368 		fatal_fr(r, "parse host");
1369 	if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
1370 		cp[len - 1] = '\0';
1371 	if (strcmp(cp, chost) != 0)
1372 		fail++;
1373 	free(cp);
1374 
1375 	/* verify client user */
1376 	if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1377 		fatal_fr(r, "parse ruser");
1378 	if (strcmp(cp, cuser) != 0)
1379 		fail++;
1380 	free(cp);
1381 
1382 	if (sshbuf_len(b) != 0)
1383 		fail++;
1384 	sshbuf_free(b);
1385 	return (fail == 0);
1386 }
1387 
1388 int
1389 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
1390 {
1391 	struct sshkey *key;
1392 	const u_char *signature, *data, *blob;
1393 	char *sigalg = NULL, *fp = NULL;
1394 	size_t signaturelen, datalen, bloblen;
1395 	int r, ret, req_presence = 0, req_verify = 0, valid_data = 0;
1396 	int encoded_ret;
1397 	struct sshkey_sig_details *sig_details = NULL;
1398 
1399 	if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 ||
1400 	    (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 ||
1401 	    (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 ||
1402 	    (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
1403 		fatal_fr(r, "parse");
1404 
1405 	if (hostbased_cuser == NULL || hostbased_chost == NULL ||
1406 	  !monitor_allowed_key(blob, bloblen))
1407 		fatal_f("bad key, not previously allowed");
1408 
1409 	/* Empty signature algorithm means NULL. */
1410 	if (*sigalg == '\0') {
1411 		free(sigalg);
1412 		sigalg = NULL;
1413 	}
1414 
1415 	/* XXX use sshkey_froms here; need to change key_blob, etc. */
1416 	if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
1417 		fatal_fr(r, "parse key");
1418 
1419 	switch (key_blobtype) {
1420 	case MM_USERKEY:
1421 		valid_data = monitor_valid_userblob(ssh, data, datalen);
1422 		auth_method = "publickey";
1423 		break;
1424 	case MM_HOSTKEY:
1425 		valid_data = monitor_valid_hostbasedblob(data, datalen,
1426 		    hostbased_cuser, hostbased_chost);
1427 		auth_method = "hostbased";
1428 		break;
1429 	default:
1430 		valid_data = 0;
1431 		break;
1432 	}
1433 	if (!valid_data)
1434 		fatal_f("bad signature data blob");
1435 
1436 	if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
1437 	    SSH_FP_DEFAULT)) == NULL)
1438 		fatal_f("sshkey_fingerprint failed");
1439 
1440 	ret = sshkey_verify(key, signature, signaturelen, data, datalen,
1441 	    sigalg, ssh->compat, &sig_details);
1442 	debug3_f("%s %p signature %s%s%s", auth_method, key,
1443 	    (ret == 0) ? "verified" : "unverified",
1444 	    (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : "");
1445 
1446 	if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
1447 		req_presence = (options.pubkey_auth_options &
1448 		    PUBKEYAUTH_TOUCH_REQUIRED) ||
1449 		    !key_opts->no_require_user_presence;
1450 		if (req_presence &&
1451 		    (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
1452 			error("public key %s %s signature for %s%s from %.128s "
1453 			    "port %d rejected: user presence "
1454 			    "(authenticator touch) requirement not met ",
1455 			    sshkey_type(key), fp,
1456 			    authctxt->valid ? "" : "invalid user ",
1457 			    authctxt->user, ssh_remote_ipaddr(ssh),
1458 			    ssh_remote_port(ssh));
1459 			ret = SSH_ERR_SIGNATURE_INVALID;
1460 		}
1461 		req_verify = (options.pubkey_auth_options &
1462 		    PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify;
1463 		if (req_verify &&
1464 		    (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) {
1465 			error("public key %s %s signature for %s%s from %.128s "
1466 			    "port %d rejected: user verification requirement "
1467 			    "not met ", sshkey_type(key), fp,
1468 			    authctxt->valid ? "" : "invalid user ",
1469 			    authctxt->user, ssh_remote_ipaddr(ssh),
1470 			    ssh_remote_port(ssh));
1471 			ret = SSH_ERR_SIGNATURE_INVALID;
1472 		}
1473 	}
1474 	auth2_record_key(authctxt, ret == 0, key);
1475 
1476 	if (key_blobtype == MM_USERKEY)
1477 		auth_activate_options(ssh, key_opts);
1478 	monitor_reset_key_state();
1479 
1480 	sshbuf_reset(m);
1481 
1482 	/* encode ret != 0 as positive integer, since we're sending u32 */
1483 	encoded_ret = (ret != 0);
1484 	if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 ||
1485 	    (r = sshbuf_put_u8(m, sig_details != NULL)) != 0)
1486 		fatal_fr(r, "assemble");
1487 	if (sig_details != NULL) {
1488 		if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 ||
1489 		    (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0)
1490 			fatal_fr(r, "assemble sk");
1491 	}
1492 	sshkey_sig_details_free(sig_details);
1493 	mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
1494 
1495 	free(sigalg);
1496 	free(fp);
1497 	sshkey_free(key);
1498 
1499 	return ret == 0;
1500 }
1501 
1502 static void
1503 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw)
1504 {
1505 	socklen_t fromlen;
1506 	struct sockaddr_storage from;
1507 
1508 	/*
1509 	 * Get IP address of client. If the connection is not a socket, let
1510 	 * the address be 0.0.0.0.
1511 	 */
1512 	memset(&from, 0, sizeof(from));
1513 	fromlen = sizeof(from);
1514 	if (ssh_packet_connection_is_on_socket(ssh)) {
1515 		if (getpeername(ssh_packet_get_connection_in(ssh),
1516 		    (struct sockaddr *)&from, &fromlen) == -1) {
1517 			debug("getpeername: %.100s", strerror(errno));
1518 			cleanup_exit(255);
1519 		}
1520 	}
1521 	/* Record that there was a login on that tty from the remote host. */
1522 	record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
1523 	    session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
1524 	    (struct sockaddr *)&from, fromlen);
1525 }
1526 
1527 static void
1528 mm_session_close(Session *s)
1529 {
1530 	debug3_f("session %d pid %ld", s->self, (long)s->pid);
1531 	if (s->ttyfd != -1) {
1532 		debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd);
1533 		session_pty_cleanup2(s);
1534 	}
1535 	session_unused(s->self);
1536 }
1537 
1538 int
1539 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m)
1540 {
1541 	extern struct monitor *pmonitor;
1542 	Session *s;
1543 	int r, res, fd0;
1544 
1545 	debug3_f("entering");
1546 
1547 	sshbuf_reset(m);
1548 	s = session_new();
1549 	if (s == NULL)
1550 		goto error;
1551 	s->authctxt = authctxt;
1552 	s->pw = authctxt->pw;
1553 	s->pid = pmonitor->m_pid;
1554 	res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
1555 	if (res == 0)
1556 		goto error;
1557 	pty_setowner(authctxt->pw, s->tty);
1558 
1559 	if ((r = sshbuf_put_u32(m, 1)) != 0 ||
1560 	    (r = sshbuf_put_cstring(m, s->tty)) != 0)
1561 		fatal_fr(r, "assemble");
1562 
1563 	/* We need to trick ttyslot */
1564 	if (dup2(s->ttyfd, 0) == -1)
1565 		fatal_f("dup2");
1566 
1567 	mm_record_login(ssh, s, authctxt->pw);
1568 
1569 	/* Now we can close the file descriptor again */
1570 	close(0);
1571 
1572 	/* send messages generated by record_login */
1573 	if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
1574 		fatal_fr(r, "assemble loginmsg");
1575 	sshbuf_reset(loginmsg);
1576 
1577 	mm_request_send(sock, MONITOR_ANS_PTY, m);
1578 
1579 	if (mm_send_fd(sock, s->ptyfd) == -1 ||
1580 	    mm_send_fd(sock, s->ttyfd) == -1)
1581 		fatal_f("send fds failed");
1582 
1583 	/* make sure nothing uses fd 0 */
1584 	if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1585 		fatal_f("open(/dev/null): %s", strerror(errno));
1586 	if (fd0 != 0)
1587 		error_f("fd0 %d != 0", fd0);
1588 
1589 	/* slave side of pty is not needed */
1590 	close(s->ttyfd);
1591 	s->ttyfd = s->ptyfd;
1592 	/* no need to dup() because nobody closes ptyfd */
1593 	s->ptymaster = s->ptyfd;
1594 
1595 	debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd);
1596 
1597 	return (0);
1598 
1599  error:
1600 	if (s != NULL)
1601 		mm_session_close(s);
1602 	if ((r = sshbuf_put_u32(m, 0)) != 0)
1603 		fatal_fr(r, "assemble 0");
1604 	mm_request_send(sock, MONITOR_ANS_PTY, m);
1605 	return (0);
1606 }
1607 
1608 int
1609 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m)
1610 {
1611 	Session *s;
1612 	char *tty;
1613 	int r;
1614 
1615 	debug3_f("entering");
1616 
1617 	if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
1618 		fatal_fr(r, "parse tty");
1619 	if ((s = session_by_tty(tty)) != NULL)
1620 		mm_session_close(s);
1621 	sshbuf_reset(m);
1622 	free(tty);
1623 	return (0);
1624 }
1625 
1626 int
1627 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req)
1628 {
1629 	extern struct monitor *pmonitor;
1630 	int res, status;
1631 
1632 	debug3_f("tearing down sessions");
1633 
1634 	/* The child is terminating */
1635 	session_destroy_all(ssh, &mm_session_close);
1636 
1637 #ifdef USE_PAM
1638 	if (options.use_pam)
1639 		sshpam_cleanup();
1640 #endif
1641 
1642 	while (waitpid(pmonitor->m_pid, &status, 0) == -1)
1643 		if (errno != EINTR)
1644 			exit(1);
1645 
1646 	res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
1647 
1648 	/* Terminate process */
1649 	exit(res);
1650 }
1651 
1652 #ifdef SSH_AUDIT_EVENTS
1653 /* Report that an audit event occurred */
1654 int
1655 mm_answer_audit_event(struct ssh *ssh, int socket, struct sshbuf *m)
1656 {
1657 	u_int n;
1658 	ssh_audit_event_t event;
1659 	int r;
1660 
1661 	debug3("%s entering", __func__);
1662 
1663 	if ((r = sshbuf_get_u32(m, &n)) != 0)
1664 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1665 	event = (ssh_audit_event_t)n;
1666 	switch (event) {
1667 	case SSH_AUTH_FAIL_PUBKEY:
1668 	case SSH_AUTH_FAIL_HOSTBASED:
1669 	case SSH_AUTH_FAIL_GSSAPI:
1670 	case SSH_LOGIN_EXCEED_MAXTRIES:
1671 	case SSH_LOGIN_ROOT_DENIED:
1672 	case SSH_CONNECTION_CLOSE:
1673 	case SSH_INVALID_USER:
1674 		audit_event(ssh, event);
1675 		break;
1676 	default:
1677 		fatal("Audit event type %d not permitted", event);
1678 	}
1679 
1680 	return (0);
1681 }
1682 
1683 int
1684 mm_answer_audit_command(struct ssh *ssh, int socket, struct sshbuf *m)
1685 {
1686 	char *cmd;
1687 	int r;
1688 
1689 	debug3("%s entering", __func__);
1690 	if ((r = sshbuf_get_cstring(m, &cmd, NULL)) != 0)
1691 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1692 	/* sanity check command, if so how? */
1693 	audit_run_command(cmd);
1694 	free(cmd);
1695 	return (0);
1696 }
1697 #endif /* SSH_AUDIT_EVENTS */
1698 
1699 void
1700 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor)
1701 {
1702 	ssh_clear_newkeys(ssh, MODE_IN);
1703 	ssh_clear_newkeys(ssh, MODE_OUT);
1704 	sshbuf_free(child_state);
1705 	child_state = NULL;
1706 }
1707 
1708 void
1709 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
1710 {
1711 	struct kex *kex;
1712 	int r;
1713 
1714 	debug3_f("packet_set_state");
1715 	if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
1716 		fatal_fr(r, "packet_set_state");
1717 	sshbuf_free(child_state);
1718 	child_state = NULL;
1719 
1720 	if ((kex = ssh->kex) != NULL) {
1721 		/* XXX set callbacks */
1722 #ifdef WITH_OPENSSL
1723 		kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1724 		kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1725 		kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1726 		kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1727 		kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1728 		kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1729 		kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1730 # ifdef OPENSSL_HAS_ECC
1731 		kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1732 # endif
1733 #endif /* WITH_OPENSSL */
1734 		kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1735 		kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1736 		kex->load_host_public_key=&get_hostkey_public_by_type;
1737 		kex->load_host_private_key=&get_hostkey_private_by_type;
1738 		kex->host_key_index=&get_hostkey_index;
1739 		kex->sign = sshd_hostkey_sign;
1740 	}
1741 }
1742 
1743 /* This function requires careful sanity checking */
1744 
1745 void
1746 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor)
1747 {
1748 	debug3_f("Waiting for new keys");
1749 
1750 	if ((child_state = sshbuf_new()) == NULL)
1751 		fatal_f("sshbuf_new failed");
1752 	mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
1753 	    child_state);
1754 	debug3_f("GOT new keys");
1755 }
1756 
1757 
1758 /* XXX */
1759 
1760 #define FD_CLOSEONEXEC(x) do { \
1761 	if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
1762 		fatal("fcntl(%d, F_SETFD)", x); \
1763 } while (0)
1764 
1765 static void
1766 monitor_openfds(struct monitor *mon, int do_logfds)
1767 {
1768 	int pair[2];
1769 #ifdef SO_ZEROIZE
1770 	int on = 1;
1771 #endif
1772 
1773 	if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
1774 		fatal_f("socketpair: %s", strerror(errno));
1775 #ifdef SO_ZEROIZE
1776 	if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1777 		error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
1778 	if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1779 		error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
1780 #endif
1781 	FD_CLOSEONEXEC(pair[0]);
1782 	FD_CLOSEONEXEC(pair[1]);
1783 	mon->m_recvfd = pair[0];
1784 	mon->m_sendfd = pair[1];
1785 
1786 	if (do_logfds) {
1787 		if (pipe(pair) == -1)
1788 			fatal_f("pipe: %s", strerror(errno));
1789 		FD_CLOSEONEXEC(pair[0]);
1790 		FD_CLOSEONEXEC(pair[1]);
1791 		mon->m_log_recvfd = pair[0];
1792 		mon->m_log_sendfd = pair[1];
1793 	} else
1794 		mon->m_log_recvfd = mon->m_log_sendfd = -1;
1795 }
1796 
1797 #define MM_MEMSIZE	65536
1798 
1799 struct monitor *
1800 monitor_init(void)
1801 {
1802 	struct monitor *mon;
1803 
1804 	mon = xcalloc(1, sizeof(*mon));
1805 	monitor_openfds(mon, 1);
1806 
1807 	return mon;
1808 }
1809 
1810 void
1811 monitor_reinit(struct monitor *mon)
1812 {
1813 	monitor_openfds(mon, 0);
1814 }
1815 
1816 #ifdef GSSAPI
1817 int
1818 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1819 {
1820 	gss_OID_desc goid;
1821 	OM_uint32 major;
1822 	size_t len;
1823 	u_char *p;
1824 	int r;
1825 
1826 	if (!options.gss_authentication)
1827 		fatal_f("GSSAPI authentication not enabled");
1828 
1829 	if ((r = sshbuf_get_string(m, &p, &len)) != 0)
1830 		fatal_fr(r, "parse");
1831 	goid.elements = p;
1832 	goid.length = len;
1833 
1834 	major = ssh_gssapi_server_ctx(&gsscontext, &goid);
1835 
1836 	free(goid.elements);
1837 
1838 	sshbuf_reset(m);
1839 	if ((r = sshbuf_put_u32(m, major)) != 0)
1840 		fatal_fr(r, "assemble");
1841 
1842 	mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
1843 
1844 	/* Now we have a context, enable the step */
1845 	monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
1846 
1847 	return (0);
1848 }
1849 
1850 int
1851 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1852 {
1853 	gss_buffer_desc in;
1854 	gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
1855 	OM_uint32 major, minor;
1856 	OM_uint32 flags = 0; /* GSI needs this */
1857 	int r;
1858 
1859 	if (!options.gss_authentication)
1860 		fatal_f("GSSAPI authentication not enabled");
1861 
1862 	if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
1863 		fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1864 	major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
1865 	free(in.value);
1866 
1867 	sshbuf_reset(m);
1868 	if ((r = sshbuf_put_u32(m, major)) != 0 ||
1869 	    (r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
1870 	    (r = sshbuf_put_u32(m, flags)) != 0)
1871 		fatal_fr(r, "assemble");
1872 	mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
1873 
1874 	gss_release_buffer(&minor, &out);
1875 
1876 	if (major == GSS_S_COMPLETE) {
1877 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
1878 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1879 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
1880 	}
1881 	return (0);
1882 }
1883 
1884 int
1885 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
1886 {
1887 	gss_buffer_desc gssbuf, mic;
1888 	OM_uint32 ret;
1889 	int r;
1890 
1891 	if (!options.gss_authentication)
1892 		fatal_f("GSSAPI authentication not enabled");
1893 
1894 	if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
1895 	    (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
1896 		fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1897 
1898 	ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
1899 
1900 	free(gssbuf.value);
1901 	free(mic.value);
1902 
1903 	sshbuf_reset(m);
1904 	if ((r = sshbuf_put_u32(m, ret)) != 0)
1905 		fatal_fr(r, "assemble");
1906 
1907 	mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
1908 
1909 	if (!GSS_ERROR(ret))
1910 		monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1911 
1912 	return (0);
1913 }
1914 
1915 int
1916 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
1917 {
1918 	int r, authenticated;
1919 	const char *displayname;
1920 
1921 	if (!options.gss_authentication)
1922 		fatal_f("GSSAPI authentication not enabled");
1923 
1924 	authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
1925 
1926 	sshbuf_reset(m);
1927 	if ((r = sshbuf_put_u32(m, authenticated)) != 0)
1928 		fatal_fr(r, "assemble");
1929 
1930 	debug3_f("sending result %d", authenticated);
1931 	mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
1932 
1933 	auth_method = "gssapi-with-mic";
1934 
1935 	if ((displayname = ssh_gssapi_displayname()) != NULL)
1936 		auth2_record_info(authctxt, "%s", displayname);
1937 
1938 	/* Monitor loop will terminate if authenticated */
1939 	return (authenticated);
1940 }
1941 #endif /* GSSAPI */
1942 
1943