1/* $OpenBSD: auth2.c,v 1.169 2024/05/17 00:30:23 djm 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 <sys/types.h>
27#include <sys/stat.h>
28#include <sys/uio.h>
29
30#include <fcntl.h>
31#include <limits.h>
32#include <pwd.h>
33#include <stdarg.h>
34#include <string.h>
35#include <unistd.h>
36#include <time.h>
37
38#include "stdlib.h"
39#include "atomicio.h"
40#include "xmalloc.h"
41#include "ssh2.h"
42#include "packet.h"
43#include "log.h"
44#include "sshbuf.h"
45#include "misc.h"
46#include "servconf.h"
47#include "sshkey.h"
48#include "hostfile.h"
49#include "auth.h"
50#include "dispatch.h"
51#include "pathnames.h"
52#ifdef GSSAPI
53#include "ssh-gss.h"
54#endif
55#include "monitor_wrap.h"
56#include "ssherr.h"
57#include "digest.h"
58#include "kex.h"
59
60/* import */
61extern ServerOptions options;
62
63/* methods */
64
65extern Authmethod method_none;
66extern Authmethod method_pubkey;
67extern Authmethod method_passwd;
68extern Authmethod method_kbdint;
69extern Authmethod method_hostbased;
70#ifdef GSSAPI
71extern Authmethod method_gssapi;
72#endif
73
74Authmethod *authmethods[] = {
75	&method_none,
76	&method_pubkey,
77#ifdef GSSAPI
78	&method_gssapi,
79#endif
80	&method_passwd,
81	&method_kbdint,
82	&method_hostbased,
83	NULL
84};
85
86/* protocol */
87
88static int input_service_request(int, u_int32_t, struct ssh *);
89static int input_userauth_request(int, u_int32_t, struct ssh *);
90
91/* helper */
92static Authmethod *authmethod_byname(const char *);
93static Authmethod *authmethod_lookup(Authctxt *, const char *);
94static char *authmethods_get(Authctxt *authctxt);
95
96#define MATCH_NONE	0	/* method or submethod mismatch */
97#define MATCH_METHOD	1	/* method matches (no submethod specified) */
98#define MATCH_BOTH	2	/* method and submethod match */
99#define MATCH_PARTIAL	3	/* method matches, submethod can't be checked */
100static int list_starts_with(const char *, const char *, const char *);
101
102char *
103auth2_read_banner(void)
104{
105	struct stat st;
106	char *banner = NULL;
107	size_t len, n;
108	int fd;
109
110	if ((fd = open(options.banner, O_RDONLY)) == -1)
111		return (NULL);
112	if (fstat(fd, &st) == -1) {
113		close(fd);
114		return (NULL);
115	}
116	if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
117		close(fd);
118		return (NULL);
119	}
120
121	len = (size_t)st.st_size;		/* truncate */
122	banner = xmalloc(len + 1);
123	n = atomicio(read, fd, banner, len);
124	close(fd);
125
126	if (n != len) {
127		free(banner);
128		return (NULL);
129	}
130	banner[n] = '\0';
131
132	return (banner);
133}
134
135static void
136userauth_banner(struct ssh *ssh)
137{
138	char *banner = NULL;
139	int r;
140
141	if (options.banner == NULL)
142		return;
143
144	if ((banner = mm_auth2_read_banner()) == NULL)
145		goto done;
146
147	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
148	    (r = sshpkt_put_cstring(ssh, banner)) != 0 ||
149	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||	/* language, unused */
150	    (r = sshpkt_send(ssh)) != 0)
151		fatal_fr(r, "send packet");
152	debug("userauth_banner: sent");
153done:
154	free(banner);
155}
156
157/*
158 * loop until authctxt->success == TRUE
159 */
160void
161do_authentication2(struct ssh *ssh)
162{
163	Authctxt *authctxt = ssh->authctxt;
164
165	ssh_dispatch_init(ssh, &dispatch_protocol_error);
166	if (ssh->kex->ext_info_c)
167		ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
168	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
169	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
170	ssh->authctxt = NULL;
171}
172
173static int
174input_service_request(int type, u_int32_t seq, struct ssh *ssh)
175{
176	Authctxt *authctxt = ssh->authctxt;
177	char *service = NULL;
178	int r, acceptit = 0;
179
180	if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
181	    (r = sshpkt_get_end(ssh)) != 0)
182		goto out;
183
184	if (authctxt == NULL)
185		fatal("input_service_request: no authctxt");
186
187	if (strcmp(service, "ssh-userauth") == 0) {
188		if (!authctxt->success) {
189			acceptit = 1;
190			/* now we can handle user-auth requests */
191			ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
192			    &input_userauth_request);
193		}
194	}
195	/* XXX all other service requests are denied */
196
197	if (acceptit) {
198		if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
199		    (r = sshpkt_put_cstring(ssh, service)) != 0 ||
200		    (r = sshpkt_send(ssh)) != 0 ||
201		    (r = ssh_packet_write_wait(ssh)) != 0)
202			goto out;
203	} else {
204		debug("bad service request %s", service);
205		ssh_packet_disconnect(ssh, "bad service request %s", service);
206	}
207	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error);
208	r = 0;
209 out:
210	free(service);
211	return r;
212}
213
214#define MIN_FAIL_DELAY_SECONDS 0.005
215#define MAX_FAIL_DELAY_SECONDS 5.0
216static double
217user_specific_delay(const char *user)
218{
219	char b[512];
220	size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
221	u_char *hash = xmalloc(len);
222	double delay;
223
224	(void)snprintf(b, sizeof b, "%llu%s",
225	    (unsigned long long)options.timing_secret, user);
226	if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
227		fatal_f("ssh_digest_memory");
228	/* 0-4.2 ms of delay */
229	delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
230	freezero(hash, len);
231	debug3_f("user specific delay %0.3lfms", delay/1000);
232	return MIN_FAIL_DELAY_SECONDS + delay;
233}
234
235static void
236ensure_minimum_time_since(double start, double seconds)
237{
238	struct timespec ts;
239	double elapsed = monotime_double() - start, req = seconds, remain;
240
241	if (elapsed > MAX_FAIL_DELAY_SECONDS) {
242		debug3_f("elapsed %0.3lfms exceeded the max delay "
243		    "requested %0.3lfms)", elapsed*1000, req*1000);
244		return;
245	}
246
247	/* if we've already passed the requested time, scale up */
248	while ((remain = seconds - elapsed) < 0.0)
249		seconds *= 2;
250
251	ts.tv_sec = remain;
252	ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
253	debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
254	    elapsed*1000, remain*1000, req*1000);
255	nanosleep(&ts, NULL);
256}
257
258static int
259input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
260{
261	Authctxt *authctxt = ssh->authctxt;
262	Authmethod *m = NULL;
263	char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
264	int r, authenticated = 0;
265	double tstart = monotime_double();
266
267	if (authctxt == NULL)
268		fatal("input_userauth_request: no authctxt");
269
270	if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
271	    (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
272	    (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
273		goto out;
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 >= 1024)
281		auth_maxtries_exceeded(ssh);
282	if (authctxt->attempt++ == 0) {
283		/* setup auth context */
284		authctxt->pw = mm_getpwnamallow(ssh, user);
285		if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
286			authctxt->valid = 1;
287			debug2_f("setting up authctxt for %s", user);
288		} else {
289			authctxt->valid = 0;
290			/* Invalid user, fake password information */
291			authctxt->pw = fakepw();
292		}
293		ssh_packet_set_log_preamble(ssh, "%suser %s",
294		    authctxt->valid ? "authenticating " : "invalid ", user);
295		setproctitle("%s [net]", authctxt->valid ? user : "unknown");
296		authctxt->user = xstrdup(user);
297		authctxt->service = xstrdup(service);
298		authctxt->style = style ? xstrdup(style) : NULL;
299		mm_inform_authserv(service, style);
300		userauth_banner(ssh);
301		if ((r = kex_server_update_ext_info(ssh)) != 0)
302			fatal_fr(r, "kex_server_update_ext_info failed");
303		if (auth2_setup_methods_lists(authctxt) != 0)
304			ssh_packet_disconnect(ssh,
305			    "no authentication methods enabled");
306	} else if (strcmp(user, authctxt->user) != 0 ||
307	    strcmp(service, authctxt->service) != 0) {
308		ssh_packet_disconnect(ssh, "Change of username or service "
309		    "not allowed: (%s,%s) -> (%s,%s)",
310		    authctxt->user, authctxt->service, user, service);
311	}
312	/* reset state */
313	auth2_challenge_stop(ssh);
314
315#ifdef GSSAPI
316	/* XXX move to auth2_gssapi_stop() */
317	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
318	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
319#endif
320
321	auth2_authctxt_reset_info(authctxt);
322	authctxt->postponed = 0;
323	authctxt->server_caused_failure = 0;
324
325	/* try to authenticate user */
326	m = authmethod_lookup(authctxt, method);
327	if (m != NULL && authctxt->failures < options.max_authtries) {
328		debug2("input_userauth_request: try method %s", method);
329		authenticated =	m->userauth(ssh, method);
330	}
331	if (!authctxt->authenticated && strcmp(method, "none") != 0)
332		ensure_minimum_time_since(tstart,
333		    user_specific_delay(authctxt->user));
334	userauth_finish(ssh, authenticated, method, NULL);
335	r = 0;
336 out:
337	free(service);
338	free(user);
339	free(method);
340	return r;
341}
342
343void
344userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
345    const char *submethod)
346{
347	Authctxt *authctxt = ssh->authctxt;
348	Authmethod *m = NULL;
349	const char *method = packet_method;
350	char *methods;
351	int r, partial = 0;
352
353	if (authenticated) {
354		if (!authctxt->valid) {
355			fatal("INTERNAL ERROR: authenticated invalid user %s",
356			    authctxt->user);
357		}
358		if (authctxt->postponed)
359			fatal("INTERNAL ERROR: authenticated and postponed");
360		/* prefer primary authmethod name to possible synonym */
361		if ((m = authmethod_byname(method)) == NULL)
362			fatal("INTERNAL ERROR: bad method %s", method);
363		method = m->cfg->name;
364	}
365
366	/* Special handling for root */
367	if (authenticated && authctxt->pw->pw_uid == 0 &&
368	    !auth_root_allowed(ssh, method))
369		authenticated = 0;
370
371	if (authenticated && options.num_auth_methods != 0) {
372		if (!auth2_update_methods_lists(authctxt, method, submethod)) {
373			authenticated = 0;
374			partial = 1;
375		}
376	}
377
378	/* Log before sending the reply */
379	auth_log(ssh, authenticated, partial, method, submethod);
380
381	/* Update information exposed to session */
382	if (authenticated || partial)
383		auth2_update_session_info(authctxt, method, submethod);
384
385	if (authctxt->postponed)
386		return;
387
388	if (authenticated == 1) {
389		/* turn off userauth */
390		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
391		    &dispatch_protocol_ignore);
392		if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
393		    (r = sshpkt_send(ssh)) != 0 ||
394		    (r = ssh_packet_write_wait(ssh)) != 0)
395			fatal_fr(r, "send success packet");
396		/* now we can break out */
397		authctxt->success = 1;
398		ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
399	} else {
400		/* Allow initial try of "none" auth without failure penalty */
401		if (!partial && !authctxt->server_caused_failure &&
402		    (authctxt->attempt > 1 || strcmp(method, "none") != 0))
403			authctxt->failures++;
404		if (authctxt->failures >= options.max_authtries)
405			auth_maxtries_exceeded(ssh);
406		methods = authmethods_get(authctxt);
407		debug3_f("failure partial=%d next methods=\"%s\"",
408		    partial, methods);
409		if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
410		    (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
411		    (r = sshpkt_put_u8(ssh, partial)) != 0 ||
412		    (r = sshpkt_send(ssh)) != 0 ||
413		    (r = ssh_packet_write_wait(ssh)) != 0)
414			fatal_fr(r, "send failure packet");
415		free(methods);
416	}
417}
418
419/*
420 * Checks whether method is allowed by at least one AuthenticationMethods
421 * methods list. Returns 1 if allowed, or no methods lists configured.
422 * 0 otherwise.
423 */
424int
425auth2_method_allowed(Authctxt *authctxt, const char *method,
426    const char *submethod)
427{
428	u_int i;
429
430	/*
431	 * NB. authctxt->num_auth_methods might be zero as a result of
432	 * auth2_setup_methods_lists(), so check the configuration.
433	 */
434	if (options.num_auth_methods == 0)
435		return 1;
436	for (i = 0; i < authctxt->num_auth_methods; i++) {
437		if (list_starts_with(authctxt->auth_methods[i], method,
438		    submethod) != MATCH_NONE)
439			return 1;
440	}
441	return 0;
442}
443
444static char *
445authmethods_get(Authctxt *authctxt)
446{
447	struct sshbuf *b;
448	char *list;
449	int i, r;
450
451	if ((b = sshbuf_new()) == NULL)
452		fatal_f("sshbuf_new failed");
453	for (i = 0; authmethods[i] != NULL; i++) {
454		if (strcmp(authmethods[i]->cfg->name, "none") == 0)
455			continue;
456		if (authmethods[i]->cfg->enabled == NULL ||
457		    *(authmethods[i]->cfg->enabled) == 0)
458			continue;
459		if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name,
460		    NULL))
461			continue;
462		if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
463		    authmethods[i]->cfg->name)) != 0)
464			fatal_fr(r, "buffer error");
465	}
466	if ((list = sshbuf_dup_string(b)) == NULL)
467		fatal_f("sshbuf_dup_string failed");
468	sshbuf_free(b);
469	return list;
470}
471
472static Authmethod *
473authmethod_byname(const char *name)
474{
475	int i;
476
477	if (name == NULL)
478		fatal_f("NULL authentication method name");
479	for (i = 0; authmethods[i] != NULL; i++) {
480		if (strcmp(name, authmethods[i]->cfg->name) == 0 ||
481		    (authmethods[i]->cfg->synonym != NULL &&
482		    strcmp(name, authmethods[i]->cfg->synonym) == 0))
483			return authmethods[i];
484	}
485	debug_f("unrecognized authentication method name: %s", name);
486	return NULL;
487}
488
489static Authmethod *
490authmethod_lookup(Authctxt *authctxt, const char *name)
491{
492	Authmethod *method;
493
494	if ((method = authmethod_byname(name)) == NULL)
495		return NULL;
496
497	if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) {
498		debug3_f("method %s not enabled", name);
499		return NULL;
500	}
501	if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) {
502		debug3_f("method %s not allowed "
503		    "by AuthenticationMethods", name);
504		return NULL;
505	}
506	return method;
507}
508
509/*
510 * Prune the AuthenticationMethods supplied in the configuration, removing
511 * any methods lists that include disabled methods. Note that this might
512 * leave authctxt->num_auth_methods == 0, even when multiple required auth
513 * has been requested. For this reason, all tests for whether multiple is
514 * enabled should consult options.num_auth_methods directly.
515 */
516int
517auth2_setup_methods_lists(Authctxt *authctxt)
518{
519	u_int i;
520
521	/* First, normalise away the "any" pseudo-method */
522	if (options.num_auth_methods == 1 &&
523	    strcmp(options.auth_methods[0], "any") == 0) {
524		free(options.auth_methods[0]);
525		options.auth_methods[0] = NULL;
526		options.num_auth_methods = 0;
527	}
528
529	if (options.num_auth_methods == 0)
530		return 0;
531	debug3_f("checking methods");
532	authctxt->auth_methods = xcalloc(options.num_auth_methods,
533	    sizeof(*authctxt->auth_methods));
534	authctxt->num_auth_methods = 0;
535	for (i = 0; i < options.num_auth_methods; i++) {
536		if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
537			logit("Authentication methods list \"%s\" contains "
538			    "disabled method, skipping",
539			    options.auth_methods[i]);
540			continue;
541		}
542		debug("authentication methods list %d: %s",
543		    authctxt->num_auth_methods, options.auth_methods[i]);
544		authctxt->auth_methods[authctxt->num_auth_methods++] =
545		    xstrdup(options.auth_methods[i]);
546	}
547	if (authctxt->num_auth_methods == 0) {
548		error("No AuthenticationMethods left after eliminating "
549		    "disabled methods");
550		return -1;
551	}
552	return 0;
553}
554
555static int
556list_starts_with(const char *methods, const char *method,
557    const char *submethod)
558{
559	size_t l = strlen(method);
560	int match;
561	const char *p;
562
563	if (strncmp(methods, method, l) != 0)
564		return MATCH_NONE;
565	p = methods + l;
566	match = MATCH_METHOD;
567	if (*p == ':') {
568		if (!submethod)
569			return MATCH_PARTIAL;
570		l = strlen(submethod);
571		p += 1;
572		if (strncmp(submethod, p, l))
573			return MATCH_NONE;
574		p += l;
575		match = MATCH_BOTH;
576	}
577	if (*p != ',' && *p != '\0')
578		return MATCH_NONE;
579	return match;
580}
581
582/*
583 * Remove method from the start of a comma-separated list of methods.
584 * Returns 0 if the list of methods did not start with that method or 1
585 * if it did.
586 */
587static int
588remove_method(char **methods, const char *method, const char *submethod)
589{
590	char *omethods = *methods, *p;
591	size_t l = strlen(method);
592	int match;
593
594	match = list_starts_with(omethods, method, submethod);
595	if (match != MATCH_METHOD && match != MATCH_BOTH)
596		return 0;
597	p = omethods + l;
598	if (submethod && match == MATCH_BOTH)
599		p += 1 + strlen(submethod); /* include colon */
600	if (*p == ',')
601		p++;
602	*methods = xstrdup(p);
603	free(omethods);
604	return 1;
605}
606
607/*
608 * Called after successful authentication. Will remove the successful method
609 * from the start of each list in which it occurs. If it was the last method
610 * in any list, then authentication is deemed successful.
611 * Returns 1 if the method completed any authentication list or 0 otherwise.
612 */
613int
614auth2_update_methods_lists(Authctxt *authctxt, const char *method,
615    const char *submethod)
616{
617	u_int i, found = 0;
618
619	debug3_f("updating methods list after \"%s\"", method);
620	for (i = 0; i < authctxt->num_auth_methods; i++) {
621		if (!remove_method(&(authctxt->auth_methods[i]), method,
622		    submethod))
623			continue;
624		found = 1;
625		if (*authctxt->auth_methods[i] == '\0') {
626			debug2("authentication methods list %d complete", i);
627			return 1;
628		}
629		debug3("authentication methods list %d remaining: \"%s\"",
630		    i, authctxt->auth_methods[i]);
631	}
632	/* This should not happen, but would be bad if it did */
633	if (!found)
634		fatal_f("method not in AuthenticationMethods");
635	return 0;
636}
637
638/* Reset method-specific information */
639void auth2_authctxt_reset_info(Authctxt *authctxt)
640{
641	sshkey_free(authctxt->auth_method_key);
642	free(authctxt->auth_method_info);
643	authctxt->auth_method_key = NULL;
644	authctxt->auth_method_info = NULL;
645}
646
647/* Record auth method-specific information for logs */
648void
649auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
650{
651	va_list ap;
652	int i;
653
654	free(authctxt->auth_method_info);
655	authctxt->auth_method_info = NULL;
656
657	va_start(ap, fmt);
658	i = vasprintf(&authctxt->auth_method_info, fmt, ap);
659	va_end(ap);
660
661	if (i == -1)
662		fatal_f("vasprintf failed");
663}
664
665/*
666 * Records a public key used in authentication. This is used for logging
667 * and to ensure that the same key is not subsequently accepted again for
668 * multiple authentication.
669 */
670void
671auth2_record_key(Authctxt *authctxt, int authenticated,
672    const struct sshkey *key)
673{
674	struct sshkey **tmp, *dup;
675	int r;
676
677	if ((r = sshkey_from_private(key, &dup)) != 0)
678		fatal_fr(r, "copy key");
679	sshkey_free(authctxt->auth_method_key);
680	authctxt->auth_method_key = dup;
681
682	if (!authenticated)
683		return;
684
685	/* If authenticated, make sure we don't accept this key again */
686	if ((r = sshkey_from_private(key, &dup)) != 0)
687		fatal_fr(r, "copy key");
688	if (authctxt->nprev_keys >= INT_MAX ||
689	    (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
690	    authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
691		fatal_f("reallocarray failed");
692	authctxt->prev_keys = tmp;
693	authctxt->prev_keys[authctxt->nprev_keys] = dup;
694	authctxt->nprev_keys++;
695
696}
697
698/* Checks whether a key has already been previously used for authentication */
699int
700auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
701{
702	u_int i;
703	char *fp;
704
705	for (i = 0; i < authctxt->nprev_keys; i++) {
706		if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
707			fp = sshkey_fingerprint(authctxt->prev_keys[i],
708			    options.fingerprint_hash, SSH_FP_DEFAULT);
709			debug3_f("key already used: %s %s",
710			    sshkey_type(authctxt->prev_keys[i]),
711			    fp == NULL ? "UNKNOWN" : fp);
712			free(fp);
713			return 1;
714		}
715	}
716	return 0;
717}
718
719/*
720 * Updates authctxt->session_info with details of authentication. Should be
721 * whenever an authentication method succeeds.
722 */
723void
724auth2_update_session_info(Authctxt *authctxt, const char *method,
725    const char *submethod)
726{
727	int r;
728
729	if (authctxt->session_info == NULL) {
730		if ((authctxt->session_info = sshbuf_new()) == NULL)
731			fatal_f("sshbuf_new");
732	}
733
734	/* Append method[/submethod] */
735	if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
736	    method, submethod == NULL ? "" : "/",
737	    submethod == NULL ? "" : submethod)) != 0)
738		fatal_fr(r, "append method");
739
740	/* Append key if present */
741	if (authctxt->auth_method_key != NULL) {
742		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
743		    (r = sshkey_format_text(authctxt->auth_method_key,
744		    authctxt->session_info)) != 0)
745			fatal_fr(r, "append key");
746	}
747
748	if (authctxt->auth_method_info != NULL) {
749		/* Ensure no ambiguity here */
750		if (strchr(authctxt->auth_method_info, '\n') != NULL)
751			fatal_f("auth_method_info contains \\n");
752		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
753		    (r = sshbuf_putf(authctxt->session_info, "%s",
754		    authctxt->auth_method_info)) != 0) {
755			fatal_fr(r, "append method info");
756		}
757	}
758	if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
759		fatal_fr(r, "append");
760}
761
762