1/* $OpenBSD: auth2.c,v 1.149 2018/07/11 18:53:29 markus Exp $ */
2/*
3 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
27__RCSID("$FreeBSD$");
28
29#include <sys/types.h>
30#include <sys/stat.h>
31#include <sys/uio.h>
32
33#include <fcntl.h>
34#include <limits.h>
35#include <pwd.h>
36#include <stdarg.h>
37#include <string.h>
38#include <unistd.h>
39
40#include "atomicio.h"
41#include "xmalloc.h"
42#include "ssh2.h"
43#include "packet.h"
44#include "log.h"
45#include "sshbuf.h"
46#include "misc.h"
47#include "servconf.h"
48#include "compat.h"
49#include "sshkey.h"
50#include "hostfile.h"
51#include "auth.h"
52#include "dispatch.h"
53#include "pathnames.h"
54#include "sshbuf.h"
55#include "ssherr.h"
56#include "blacklist_client.h"
57
58#ifdef GSSAPI
59#include "ssh-gss.h"
60#endif
61#include "monitor_wrap.h"
62#include "ssherr.h"
63#include "digest.h"
64
65/* import */
66extern ServerOptions options;
67extern u_char *session_id2;
68extern u_int session_id2_len;
69extern struct sshbuf *loginmsg;
70
71/* methods */
72
73extern Authmethod method_none;
74extern Authmethod method_pubkey;
75extern Authmethod method_passwd;
76extern Authmethod method_kbdint;
77extern Authmethod method_hostbased;
78#ifdef GSSAPI
79extern Authmethod method_gssapi;
80#endif
81
82Authmethod *authmethods[] = {
83	&method_none,
84	&method_pubkey,
85#ifdef GSSAPI
86	&method_gssapi,
87#endif
88	&method_passwd,
89	&method_kbdint,
90	&method_hostbased,
91	NULL
92};
93
94/* protocol */
95
96static int input_service_request(int, u_int32_t, struct ssh *);
97static int input_userauth_request(int, u_int32_t, struct ssh *);
98
99/* helper */
100static Authmethod *authmethod_lookup(Authctxt *, const char *);
101static char *authmethods_get(Authctxt *authctxt);
102
103#define MATCH_NONE	0	/* method or submethod mismatch */
104#define MATCH_METHOD	1	/* method matches (no submethod specified) */
105#define MATCH_BOTH	2	/* method and submethod match */
106#define MATCH_PARTIAL	3	/* method matches, submethod can't be checked */
107static int list_starts_with(const char *, const char *, const char *);
108
109char *
110auth2_read_banner(void)
111{
112	struct stat st;
113	char *banner = NULL;
114	size_t len, n;
115	int fd;
116
117	if ((fd = open(options.banner, O_RDONLY)) == -1)
118		return (NULL);
119	if (fstat(fd, &st) == -1) {
120		close(fd);
121		return (NULL);
122	}
123	if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
124		close(fd);
125		return (NULL);
126	}
127
128	len = (size_t)st.st_size;		/* truncate */
129	banner = xmalloc(len + 1);
130	n = atomicio(read, fd, banner, len);
131	close(fd);
132
133	if (n != len) {
134		free(banner);
135		return (NULL);
136	}
137	banner[n] = '\0';
138
139	return (banner);
140}
141
142void
143userauth_send_banner(const char *msg)
144{
145	packet_start(SSH2_MSG_USERAUTH_BANNER);
146	packet_put_cstring(msg);
147	packet_put_cstring("");		/* language, unused */
148	packet_send();
149	debug("%s: sent", __func__);
150}
151
152static void
153userauth_banner(void)
154{
155	char *banner = NULL;
156
157	if (options.banner == NULL)
158		return;
159
160	if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
161		goto done;
162	userauth_send_banner(banner);
163
164done:
165	free(banner);
166}
167
168/*
169 * loop until authctxt->success == TRUE
170 */
171void
172do_authentication2(Authctxt *authctxt)
173{
174	struct ssh *ssh = active_state;		/* XXX */
175	ssh->authctxt = authctxt;		/* XXX move to caller */
176	ssh_dispatch_init(ssh, &dispatch_protocol_error);
177	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
178	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
179	ssh->authctxt = NULL;
180}
181
182/*ARGSUSED*/
183static int
184input_service_request(int type, u_int32_t seq, struct ssh *ssh)
185{
186	Authctxt *authctxt = ssh->authctxt;
187	u_int len;
188	int acceptit = 0;
189	char *service = packet_get_cstring(&len);
190	packet_check_eom();
191
192	if (authctxt == NULL)
193		fatal("input_service_request: no authctxt");
194
195	if (strcmp(service, "ssh-userauth") == 0) {
196		if (!authctxt->success) {
197			acceptit = 1;
198			/* now we can handle user-auth requests */
199			ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
200		}
201	}
202	/* XXX all other service requests are denied */
203
204	if (acceptit) {
205		packet_start(SSH2_MSG_SERVICE_ACCEPT);
206		packet_put_cstring(service);
207		packet_send();
208		packet_write_wait();
209	} else {
210		debug("bad service request %s", service);
211		packet_disconnect("bad service request %s", service);
212	}
213	free(service);
214	return 0;
215}
216
217#define MIN_FAIL_DELAY_SECONDS 0.005
218static double
219user_specific_delay(const char *user)
220{
221	char b[512];
222	size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
223	u_char *hash = xmalloc(len);
224	double delay;
225
226	(void)snprintf(b, sizeof b, "%llu%s",
227	     (unsigned long long)options.timing_secret, user);
228	if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
229		fatal("%s: ssh_digest_memory", __func__);
230	/* 0-4.2 ms of delay */
231	delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
232	freezero(hash, len);
233	debug3("%s: user specific delay %0.3lfms", __func__, delay/1000);
234	return MIN_FAIL_DELAY_SECONDS + delay;
235}
236
237static void
238ensure_minimum_time_since(double start, double seconds)
239{
240	struct timespec ts;
241	double elapsed = monotime_double() - start, req = seconds, remain;
242
243	/* if we've already passed the requested time, scale up */
244	while ((remain = seconds - elapsed) < 0.0)
245		seconds *= 2;
246
247	ts.tv_sec = remain;
248	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
249	debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
250	    __func__, elapsed*1000, remain*1000, req*1000);
251	nanosleep(&ts, NULL);
252}
253
254/*ARGSUSED*/
255static int
256input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
257{
258	Authctxt *authctxt = ssh->authctxt;
259	Authmethod *m = NULL;
260	char *user, *service, *method, *style = NULL;
261	int authenticated = 0;
262	double tstart = monotime_double();
263#ifdef HAVE_LOGIN_CAP
264	login_cap_t *lc;
265	const char *from_host, *from_ip;
266#endif
267
268	if (authctxt == NULL)
269		fatal("input_userauth_request: no authctxt");
270
271	user = packet_get_cstring(NULL);
272	service = packet_get_cstring(NULL);
273	method = packet_get_cstring(NULL);
274	debug("userauth-request for user %s service %s method %s", user, service, method);
275	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
276
277	if ((style = strchr(user, ':')) != NULL)
278		*style++ = 0;
279
280	if (authctxt->attempt++ == 0) {
281		/* setup auth context */
282		authctxt->pw = PRIVSEP(getpwnamallow(user));
283		authctxt->user = xstrdup(user);
284		if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
285			authctxt->valid = 1;
286			debug2("%s: setting up authctxt for %s",
287			    __func__, user);
288		} else {
289			/* Invalid user, fake password information */
290			authctxt->pw = fakepw();
291#ifdef SSH_AUDIT_EVENTS
292			PRIVSEP(audit_event(SSH_INVALID_USER));
293#endif
294		}
295#ifdef USE_PAM
296		if (options.use_pam)
297			PRIVSEP(start_pam(authctxt));
298#endif
299		ssh_packet_set_log_preamble(ssh, "%suser %s",
300		    authctxt->valid ? "authenticating " : "invalid ", user);
301		setproctitle("%s%s", authctxt->valid ? user : "unknown",
302		    use_privsep ? " [net]" : "");
303		authctxt->service = xstrdup(service);
304		authctxt->style = style ? xstrdup(style) : NULL;
305		if (use_privsep)
306			mm_inform_authserv(service, style);
307		userauth_banner();
308		if (auth2_setup_methods_lists(authctxt) != 0)
309			packet_disconnect("no authentication methods enabled");
310	} else if (strcmp(user, authctxt->user) != 0 ||
311	    strcmp(service, authctxt->service) != 0) {
312		packet_disconnect("Change of username or service not allowed: "
313		    "(%s,%s) -> (%s,%s)",
314		    authctxt->user, authctxt->service, user, service);
315	}
316
317#ifdef HAVE_LOGIN_CAP
318	if (authctxt->pw != NULL &&
319	    (lc = PRIVSEP(login_getpwclass(authctxt->pw))) != NULL) {
320		from_host = auth_get_canonical_hostname(ssh, options.use_dns);
321		from_ip = ssh_remote_ipaddr(ssh);
322		if (!auth_hostok(lc, from_host, from_ip)) {
323			logit("Denied connection for %.200s from %.200s [%.200s].",
324			    authctxt->pw->pw_name, from_host, from_ip);
325			packet_disconnect("Sorry, you are not allowed to connect.");
326		}
327		if (!auth_timeok(lc, time(NULL))) {
328			logit("LOGIN %.200s REFUSED (TIME) FROM %.200s",
329			    authctxt->pw->pw_name, from_host);
330			packet_disconnect("Logins not available right now.");
331		}
332		PRIVSEP(login_close(lc));
333	}
334#endif  /* HAVE_LOGIN_CAP */
335
336	/* reset state */
337	auth2_challenge_stop(ssh);
338
339#ifdef GSSAPI
340	/* XXX move to auth2_gssapi_stop() */
341	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
342	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
343#endif
344
345	auth2_authctxt_reset_info(authctxt);
346	authctxt->postponed = 0;
347	authctxt->server_caused_failure = 0;
348
349	/* try to authenticate user */
350	m = authmethod_lookup(authctxt, method);
351	if (m != NULL && authctxt->failures < options.max_authtries) {
352		debug2("input_userauth_request: try method %s", method);
353		authenticated =	m->userauth(ssh);
354	}
355	if (!authctxt->authenticated)
356		ensure_minimum_time_since(tstart,
357		    user_specific_delay(authctxt->user));
358	userauth_finish(ssh, authenticated, method, NULL);
359
360	free(service);
361	free(user);
362	free(method);
363	return 0;
364}
365
366void
367userauth_finish(struct ssh *ssh, int authenticated, const char *method,
368    const char *submethod)
369{
370	Authctxt *authctxt = ssh->authctxt;
371	char *methods;
372	int partial = 0;
373
374	if (!authctxt->valid && authenticated)
375		fatal("INTERNAL ERROR: authenticated invalid user %s",
376		    authctxt->user);
377	if (authenticated && authctxt->postponed)
378		fatal("INTERNAL ERROR: authenticated and postponed");
379
380	/* Special handling for root */
381	if (authenticated && authctxt->pw->pw_uid == 0 &&
382	    !auth_root_allowed(ssh, method)) {
383		authenticated = 0;
384#ifdef SSH_AUDIT_EVENTS
385		PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
386#endif
387	}
388
389	if (authenticated && options.num_auth_methods != 0) {
390		if (!auth2_update_methods_lists(authctxt, method, submethod)) {
391			authenticated = 0;
392			partial = 1;
393		}
394	}
395
396	/* Log before sending the reply */
397	auth_log(authctxt, authenticated, partial, method, submethod);
398
399	/* Update information exposed to session */
400	if (authenticated || partial)
401		auth2_update_session_info(authctxt, method, submethod);
402
403	if (authctxt->postponed)
404		return;
405
406#ifdef USE_PAM
407	if (options.use_pam && authenticated) {
408		int r;
409
410		if (!PRIVSEP(do_pam_account())) {
411			/* if PAM returned a message, send it to the user */
412			if (sshbuf_len(loginmsg) > 0) {
413				if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0)
414					fatal("%s: buffer error: %s",
415					    __func__, ssh_err(r));
416				userauth_send_banner(sshbuf_ptr(loginmsg));
417				packet_write_wait();
418			}
419			fatal("Access denied for user %s by PAM account "
420			    "configuration", authctxt->user);
421		}
422	}
423#endif
424
425	if (authenticated == 1) {
426		/* turn off userauth */
427		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
428		packet_start(SSH2_MSG_USERAUTH_SUCCESS);
429		packet_send();
430		packet_write_wait();
431		/* now we can break out */
432		authctxt->success = 1;
433		ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
434	} else {
435		/* Allow initial try of "none" auth without failure penalty */
436		if (!partial && !authctxt->server_caused_failure &&
437		    (authctxt->attempt > 1 || strcmp(method, "none") != 0)) {
438			authctxt->failures++;
439			BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh");
440		}
441		if (authctxt->failures >= options.max_authtries) {
442#ifdef SSH_AUDIT_EVENTS
443			PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
444#endif
445			auth_maxtries_exceeded(authctxt);
446		}
447		methods = authmethods_get(authctxt);
448		debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
449		    partial, methods);
450		packet_start(SSH2_MSG_USERAUTH_FAILURE);
451		packet_put_cstring(methods);
452		packet_put_char(partial);
453		packet_send();
454		packet_write_wait();
455		free(methods);
456	}
457}
458
459/*
460 * Checks whether method is allowed by at least one AuthenticationMethods
461 * methods list. Returns 1 if allowed, or no methods lists configured.
462 * 0 otherwise.
463 */
464int
465auth2_method_allowed(Authctxt *authctxt, const char *method,
466    const char *submethod)
467{
468	u_int i;
469
470	/*
471	 * NB. authctxt->num_auth_methods might be zero as a result of
472	 * auth2_setup_methods_lists(), so check the configuration.
473	 */
474	if (options.num_auth_methods == 0)
475		return 1;
476	for (i = 0; i < authctxt->num_auth_methods; i++) {
477		if (list_starts_with(authctxt->auth_methods[i], method,
478		    submethod) != MATCH_NONE)
479			return 1;
480	}
481	return 0;
482}
483
484static char *
485authmethods_get(Authctxt *authctxt)
486{
487	struct sshbuf *b;
488	char *list;
489	int i, r;
490
491	if ((b = sshbuf_new()) == NULL)
492		fatal("%s: sshbuf_new failed", __func__);
493	for (i = 0; authmethods[i] != NULL; i++) {
494		if (strcmp(authmethods[i]->name, "none") == 0)
495			continue;
496		if (authmethods[i]->enabled == NULL ||
497		    *(authmethods[i]->enabled) == 0)
498			continue;
499		if (!auth2_method_allowed(authctxt, authmethods[i]->name,
500		    NULL))
501			continue;
502		if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
503		    authmethods[i]->name)) != 0)
504			fatal("%s: buffer error: %s", __func__, ssh_err(r));
505	}
506	if ((list = sshbuf_dup_string(b)) == NULL)
507		fatal("%s: sshbuf_dup_string failed", __func__);
508	sshbuf_free(b);
509	return list;
510}
511
512static Authmethod *
513authmethod_lookup(Authctxt *authctxt, const char *name)
514{
515	int i;
516
517	if (name != NULL)
518		for (i = 0; authmethods[i] != NULL; i++)
519			if (authmethods[i]->enabled != NULL &&
520			    *(authmethods[i]->enabled) != 0 &&
521			    strcmp(name, authmethods[i]->name) == 0 &&
522			    auth2_method_allowed(authctxt,
523			    authmethods[i]->name, NULL))
524				return authmethods[i];
525	debug2("Unrecognized authentication method name: %s",
526	    name ? name : "NULL");
527	return NULL;
528}
529
530/*
531 * Check a comma-separated list of methods for validity. Is need_enable is
532 * non-zero, then also require that the methods are enabled.
533 * Returns 0 on success or -1 if the methods list is invalid.
534 */
535int
536auth2_methods_valid(const char *_methods, int need_enable)
537{
538	char *methods, *omethods, *method, *p;
539	u_int i, found;
540	int ret = -1;
541
542	if (*_methods == '\0') {
543		error("empty authentication method list");
544		return -1;
545	}
546	omethods = methods = xstrdup(_methods);
547	while ((method = strsep(&methods, ",")) != NULL) {
548		for (found = i = 0; !found && authmethods[i] != NULL; i++) {
549			if ((p = strchr(method, ':')) != NULL)
550				*p = '\0';
551			if (strcmp(method, authmethods[i]->name) != 0)
552				continue;
553			if (need_enable) {
554				if (authmethods[i]->enabled == NULL ||
555				    *(authmethods[i]->enabled) == 0) {
556					error("Disabled method \"%s\" in "
557					    "AuthenticationMethods list \"%s\"",
558					    method, _methods);
559					goto out;
560				}
561			}
562			found = 1;
563			break;
564		}
565		if (!found) {
566			error("Unknown authentication method \"%s\" in list",
567			    method);
568			goto out;
569		}
570	}
571	ret = 0;
572 out:
573	free(omethods);
574	return ret;
575}
576
577/*
578 * Prune the AuthenticationMethods supplied in the configuration, removing
579 * any methods lists that include disabled methods. Note that this might
580 * leave authctxt->num_auth_methods == 0, even when multiple required auth
581 * has been requested. For this reason, all tests for whether multiple is
582 * enabled should consult options.num_auth_methods directly.
583 */
584int
585auth2_setup_methods_lists(Authctxt *authctxt)
586{
587	u_int i;
588
589	if (options.num_auth_methods == 0)
590		return 0;
591	debug3("%s: checking methods", __func__);
592	authctxt->auth_methods = xcalloc(options.num_auth_methods,
593	    sizeof(*authctxt->auth_methods));
594	authctxt->num_auth_methods = 0;
595	for (i = 0; i < options.num_auth_methods; i++) {
596		if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
597			logit("Authentication methods list \"%s\" contains "
598			    "disabled method, skipping",
599			    options.auth_methods[i]);
600			continue;
601		}
602		debug("authentication methods list %d: %s",
603		    authctxt->num_auth_methods, options.auth_methods[i]);
604		authctxt->auth_methods[authctxt->num_auth_methods++] =
605		    xstrdup(options.auth_methods[i]);
606	}
607	if (authctxt->num_auth_methods == 0) {
608		error("No AuthenticationMethods left after eliminating "
609		    "disabled methods");
610		return -1;
611	}
612	return 0;
613}
614
615static int
616list_starts_with(const char *methods, const char *method,
617    const char *submethod)
618{
619	size_t l = strlen(method);
620	int match;
621	const char *p;
622
623	if (strncmp(methods, method, l) != 0)
624		return MATCH_NONE;
625	p = methods + l;
626	match = MATCH_METHOD;
627	if (*p == ':') {
628		if (!submethod)
629			return MATCH_PARTIAL;
630		l = strlen(submethod);
631		p += 1;
632		if (strncmp(submethod, p, l))
633			return MATCH_NONE;
634		p += l;
635		match = MATCH_BOTH;
636	}
637	if (*p != ',' && *p != '\0')
638		return MATCH_NONE;
639	return match;
640}
641
642/*
643 * Remove method from the start of a comma-separated list of methods.
644 * Returns 0 if the list of methods did not start with that method or 1
645 * if it did.
646 */
647static int
648remove_method(char **methods, const char *method, const char *submethod)
649{
650	char *omethods = *methods, *p;
651	size_t l = strlen(method);
652	int match;
653
654	match = list_starts_with(omethods, method, submethod);
655	if (match != MATCH_METHOD && match != MATCH_BOTH)
656		return 0;
657	p = omethods + l;
658	if (submethod && match == MATCH_BOTH)
659		p += 1 + strlen(submethod); /* include colon */
660	if (*p == ',')
661		p++;
662	*methods = xstrdup(p);
663	free(omethods);
664	return 1;
665}
666
667/*
668 * Called after successful authentication. Will remove the successful method
669 * from the start of each list in which it occurs. If it was the last method
670 * in any list, then authentication is deemed successful.
671 * Returns 1 if the method completed any authentication list or 0 otherwise.
672 */
673int
674auth2_update_methods_lists(Authctxt *authctxt, const char *method,
675    const char *submethod)
676{
677	u_int i, found = 0;
678
679	debug3("%s: updating methods list after \"%s\"", __func__, method);
680	for (i = 0; i < authctxt->num_auth_methods; i++) {
681		if (!remove_method(&(authctxt->auth_methods[i]), method,
682		    submethod))
683			continue;
684		found = 1;
685		if (*authctxt->auth_methods[i] == '\0') {
686			debug2("authentication methods list %d complete", i);
687			return 1;
688		}
689		debug3("authentication methods list %d remaining: \"%s\"",
690		    i, authctxt->auth_methods[i]);
691	}
692	/* This should not happen, but would be bad if it did */
693	if (!found)
694		fatal("%s: method not in AuthenticationMethods", __func__);
695	return 0;
696}
697
698/* Reset method-specific information */
699void auth2_authctxt_reset_info(Authctxt *authctxt)
700{
701	sshkey_free(authctxt->auth_method_key);
702	free(authctxt->auth_method_info);
703	authctxt->auth_method_key = NULL;
704	authctxt->auth_method_info = NULL;
705}
706
707/* Record auth method-specific information for logs */
708void
709auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
710{
711	va_list ap;
712        int i;
713
714	free(authctxt->auth_method_info);
715	authctxt->auth_method_info = NULL;
716
717	va_start(ap, fmt);
718	i = vasprintf(&authctxt->auth_method_info, fmt, ap);
719	va_end(ap);
720
721	if (i < 0 || authctxt->auth_method_info == NULL)
722		fatal("%s: vasprintf failed", __func__);
723}
724
725/*
726 * Records a public key used in authentication. This is used for logging
727 * and to ensure that the same key is not subsequently accepted again for
728 * multiple authentication.
729 */
730void
731auth2_record_key(Authctxt *authctxt, int authenticated,
732    const struct sshkey *key)
733{
734	struct sshkey **tmp, *dup;
735	int r;
736
737	if ((r = sshkey_from_private(key, &dup)) != 0)
738		fatal("%s: copy key: %s", __func__, ssh_err(r));
739	sshkey_free(authctxt->auth_method_key);
740	authctxt->auth_method_key = dup;
741
742	if (!authenticated)
743		return;
744
745	/* If authenticated, make sure we don't accept this key again */
746	if ((r = sshkey_from_private(key, &dup)) != 0)
747		fatal("%s: copy key: %s", __func__, ssh_err(r));
748	if (authctxt->nprev_keys >= INT_MAX ||
749	    (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
750	    authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
751		fatal("%s: reallocarray failed", __func__);
752	authctxt->prev_keys = tmp;
753	authctxt->prev_keys[authctxt->nprev_keys] = dup;
754	authctxt->nprev_keys++;
755
756}
757
758/* Checks whether a key has already been previously used for authentication */
759int
760auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
761{
762	u_int i;
763	char *fp;
764
765	for (i = 0; i < authctxt->nprev_keys; i++) {
766		if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
767			fp = sshkey_fingerprint(authctxt->prev_keys[i],
768			    options.fingerprint_hash, SSH_FP_DEFAULT);
769			debug3("%s: key already used: %s %s", __func__,
770			    sshkey_type(authctxt->prev_keys[i]),
771			    fp == NULL ? "UNKNOWN" : fp);
772			free(fp);
773			return 1;
774		}
775	}
776	return 0;
777}
778
779/*
780 * Updates authctxt->session_info with details of authentication. Should be
781 * whenever an authentication method succeeds.
782 */
783void
784auth2_update_session_info(Authctxt *authctxt, const char *method,
785    const char *submethod)
786{
787	int r;
788
789	if (authctxt->session_info == NULL) {
790		if ((authctxt->session_info = sshbuf_new()) == NULL)
791			fatal("%s: sshbuf_new", __func__);
792	}
793
794	/* Append method[/submethod] */
795	if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
796	    method, submethod == NULL ? "" : "/",
797	    submethod == NULL ? "" : submethod)) != 0)
798		fatal("%s: append method: %s", __func__, ssh_err(r));
799
800	/* Append key if present */
801	if (authctxt->auth_method_key != NULL) {
802		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
803		    (r = sshkey_format_text(authctxt->auth_method_key,
804		    authctxt->session_info)) != 0)
805			fatal("%s: append key: %s", __func__, ssh_err(r));
806	}
807
808	if (authctxt->auth_method_info != NULL) {
809		/* Ensure no ambiguity here */
810		if (strchr(authctxt->auth_method_info, '\n') != NULL)
811			fatal("%s: auth_method_info contains \\n", __func__);
812		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
813		    (r = sshbuf_putf(authctxt->session_info, "%s",
814		    authctxt->auth_method_info)) != 0) {
815			fatal("%s: append method info: %s",
816			    __func__, ssh_err(r));
817		}
818	}
819	if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
820		fatal("%s: append: %s", __func__, ssh_err(r));
821}
822
823