GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: usr.bin/ssh/sshd/../auth2.c Lines: 0 303 0.0 %
Date: 2017-11-13 Branches: 0 212 0.0 %

Line Branch Exec Source
1
/* $OpenBSD: auth2.c,v 1.143 2017/06/24 06:34:38 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
27
#include <sys/types.h>
28
#include <sys/stat.h>
29
#include <sys/uio.h>
30
31
#include <fcntl.h>
32
#include <limits.h>
33
#include <pwd.h>
34
#include <stdarg.h>
35
#include <string.h>
36
#include <unistd.h>
37
38
#include "atomicio.h"
39
#include "xmalloc.h"
40
#include "ssh2.h"
41
#include "packet.h"
42
#include "log.h"
43
#include "buffer.h"
44
#include "misc.h"
45
#include "servconf.h"
46
#include "compat.h"
47
#include "key.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
58
/* import */
59
extern ServerOptions options;
60
extern u_char *session_id2;
61
extern u_int session_id2_len;
62
63
/* methods */
64
65
extern Authmethod method_none;
66
extern Authmethod method_pubkey;
67
extern Authmethod method_passwd;
68
extern Authmethod method_kbdint;
69
extern Authmethod method_hostbased;
70
#ifdef GSSAPI
71
extern Authmethod method_gssapi;
72
#endif
73
74
Authmethod *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
88
static int input_service_request(int, u_int32_t, struct ssh *);
89
static int input_userauth_request(int, u_int32_t, struct ssh *);
90
91
/* helper */
92
static Authmethod *authmethod_lookup(Authctxt *, const char *);
93
static char *authmethods_get(Authctxt *authctxt);
94
95
#define MATCH_NONE	0	/* method or submethod mismatch */
96
#define MATCH_METHOD	1	/* method matches (no submethod specified) */
97
#define MATCH_BOTH	2	/* method and submethod match */
98
#define MATCH_PARTIAL	3	/* method matches, submethod can't be checked */
99
static int list_starts_with(const char *, const char *, const char *);
100
101
char *
102
auth2_read_banner(void)
103
{
104
	struct stat st;
105
	char *banner = NULL;
106
	size_t len, n;
107
	int fd;
108
109
	if ((fd = open(options.banner, O_RDONLY)) == -1)
110
		return (NULL);
111
	if (fstat(fd, &st) == -1) {
112
		close(fd);
113
		return (NULL);
114
	}
115
	if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
116
		close(fd);
117
		return (NULL);
118
	}
119
120
	len = (size_t)st.st_size;		/* truncate */
121
	banner = xmalloc(len + 1);
122
	n = atomicio(read, fd, banner, len);
123
	close(fd);
124
125
	if (n != len) {
126
		free(banner);
127
		return (NULL);
128
	}
129
	banner[n] = '\0';
130
131
	return (banner);
132
}
133
134
static void
135
userauth_banner(void)
136
{
137
	char *banner = NULL;
138
139
	if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0)
140
		return;
141
142
	if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
143
		goto done;
144
145
	packet_start(SSH2_MSG_USERAUTH_BANNER);
146
	packet_put_cstring(banner);
147
	packet_put_cstring("");		/* language, unused */
148
	packet_send();
149
	debug("userauth_banner: sent");
150
done:
151
	free(banner);
152
}
153
154
/*
155
 * loop until authctxt->success == TRUE
156
 */
157
void
158
do_authentication2(Authctxt *authctxt)
159
{
160
	struct ssh *ssh = active_state;		/* XXX */
161
	ssh->authctxt = authctxt;		/* XXX move to caller */
162
	ssh_dispatch_init(ssh, &dispatch_protocol_error);
163
	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
164
	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
165
	ssh->authctxt = NULL;
166
}
167
168
/*ARGSUSED*/
169
static int
170
input_service_request(int type, u_int32_t seq, struct ssh *ssh)
171
{
172
	Authctxt *authctxt = ssh->authctxt;
173
	u_int len;
174
	int acceptit = 0;
175
	char *service = packet_get_cstring(&len);
176
	packet_check_eom();
177
178
	if (authctxt == NULL)
179
		fatal("input_service_request: no authctxt");
180
181
	if (strcmp(service, "ssh-userauth") == 0) {
182
		if (!authctxt->success) {
183
			acceptit = 1;
184
			/* now we can handle user-auth requests */
185
			ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
186
		}
187
	}
188
	/* XXX all other service requests are denied */
189
190
	if (acceptit) {
191
		packet_start(SSH2_MSG_SERVICE_ACCEPT);
192
		packet_put_cstring(service);
193
		packet_send();
194
		packet_write_wait();
195
	} else {
196
		debug("bad service request %s", service);
197
		packet_disconnect("bad service request %s", service);
198
	}
199
	free(service);
200
	return 0;
201
}
202
203
/*ARGSUSED*/
204
static int
205
input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
206
{
207
	Authctxt *authctxt = ssh->authctxt;
208
	Authmethod *m = NULL;
209
	char *user, *service, *method, *style = NULL;
210
	int authenticated = 0;
211
212
	if (authctxt == NULL)
213
		fatal("input_userauth_request: no authctxt");
214
215
	user = packet_get_cstring(NULL);
216
	service = packet_get_cstring(NULL);
217
	method = packet_get_cstring(NULL);
218
	debug("userauth-request for user %s service %s method %s", user, service, method);
219
	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
220
221
	if ((style = strchr(user, ':')) != NULL)
222
		*style++ = 0;
223
224
	if (authctxt->attempt++ == 0) {
225
		/* setup auth context */
226
		authctxt->pw = PRIVSEP(getpwnamallow(user));
227
		if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
228
			authctxt->valid = 1;
229
			debug2("%s: setting up authctxt for %s",
230
			    __func__, user);
231
		} else {
232
			/* Invalid user, fake password information */
233
			authctxt->pw = fakepw();
234
		}
235
		ssh_packet_set_log_preamble(ssh, "%suser %s",
236
		    authctxt->valid ? "authenticating " : "invalid ", user);
237
		setproctitle("%s%s", authctxt->valid ? user : "unknown",
238
		    use_privsep ? " [net]" : "");
239
		authctxt->user = xstrdup(user);
240
		authctxt->service = xstrdup(service);
241
		authctxt->style = style ? xstrdup(style) : NULL;
242
		if (use_privsep)
243
			mm_inform_authserv(service, style);
244
		userauth_banner();
245
		if (auth2_setup_methods_lists(authctxt) != 0)
246
			packet_disconnect("no authentication methods enabled");
247
	} else if (strcmp(user, authctxt->user) != 0 ||
248
	    strcmp(service, authctxt->service) != 0) {
249
		packet_disconnect("Change of username or service not allowed: "
250
		    "(%s,%s) -> (%s,%s)",
251
		    authctxt->user, authctxt->service, user, service);
252
	}
253
	/* reset state */
254
	auth2_challenge_stop(ssh);
255
256
#ifdef GSSAPI
257
	/* XXX move to auth2_gssapi_stop() */
258
	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
259
	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
260
#endif
261
262
	auth2_authctxt_reset_info(authctxt);
263
	authctxt->postponed = 0;
264
	authctxt->server_caused_failure = 0;
265
266
	/* try to authenticate user */
267
	m = authmethod_lookup(authctxt, method);
268
	if (m != NULL && authctxt->failures < options.max_authtries) {
269
		debug2("input_userauth_request: try method %s", method);
270
		authenticated =	m->userauth(ssh);
271
	}
272
	userauth_finish(ssh, authenticated, method, NULL);
273
274
	free(service);
275
	free(user);
276
	free(method);
277
	return 0;
278
}
279
280
void
281
userauth_finish(struct ssh *ssh, int authenticated, const char *method,
282
    const char *submethod)
283
{
284
	Authctxt *authctxt = ssh->authctxt;
285
	char *methods;
286
	int partial = 0;
287
288
	if (!authctxt->valid && authenticated)
289
		fatal("INTERNAL ERROR: authenticated invalid user %s",
290
		    authctxt->user);
291
	if (authenticated && authctxt->postponed)
292
		fatal("INTERNAL ERROR: authenticated and postponed");
293
294
	/* Special handling for root */
295
	if (authenticated && authctxt->pw->pw_uid == 0 &&
296
	    !auth_root_allowed(method))
297
		authenticated = 0;
298
299
	if (authenticated && options.num_auth_methods != 0) {
300
		if (!auth2_update_methods_lists(authctxt, method, submethod)) {
301
			authenticated = 0;
302
			partial = 1;
303
		}
304
	}
305
306
	/* Log before sending the reply */
307
	auth_log(authctxt, authenticated, partial, method, submethod);
308
309
	/* Update information exposed to session */
310
	if (authenticated || partial)
311
		auth2_update_session_info(authctxt, method, submethod);
312
313
	if (authctxt->postponed)
314
		return;
315
316
	if (authenticated == 1) {
317
		/* turn off userauth */
318
		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
319
		packet_start(SSH2_MSG_USERAUTH_SUCCESS);
320
		packet_send();
321
		packet_write_wait();
322
		/* now we can break out */
323
		authctxt->success = 1;
324
		ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
325
	} else {
326
		/* Allow initial try of "none" auth without failure penalty */
327
		if (!partial && !authctxt->server_caused_failure &&
328
		    (authctxt->attempt > 1 || strcmp(method, "none") != 0))
329
			authctxt->failures++;
330
		if (authctxt->failures >= options.max_authtries)
331
			auth_maxtries_exceeded(authctxt);
332
		methods = authmethods_get(authctxt);
333
		debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
334
		    partial, methods);
335
		packet_start(SSH2_MSG_USERAUTH_FAILURE);
336
		packet_put_cstring(methods);
337
		packet_put_char(partial);
338
		packet_send();
339
		packet_write_wait();
340
		free(methods);
341
	}
342
}
343
344
/*
345
 * Checks whether method is allowed by at least one AuthenticationMethods
346
 * methods list. Returns 1 if allowed, or no methods lists configured.
347
 * 0 otherwise.
348
 */
349
int
350
auth2_method_allowed(Authctxt *authctxt, const char *method,
351
    const char *submethod)
352
{
353
	u_int i;
354
355
	/*
356
	 * NB. authctxt->num_auth_methods might be zero as a result of
357
	 * auth2_setup_methods_lists(), so check the configuration.
358
	 */
359
	if (options.num_auth_methods == 0)
360
		return 1;
361
	for (i = 0; i < authctxt->num_auth_methods; i++) {
362
		if (list_starts_with(authctxt->auth_methods[i], method,
363
		    submethod) != MATCH_NONE)
364
			return 1;
365
	}
366
	return 0;
367
}
368
369
static char *
370
authmethods_get(Authctxt *authctxt)
371
{
372
	Buffer b;
373
	char *list;
374
	u_int i;
375
376
	buffer_init(&b);
377
	for (i = 0; authmethods[i] != NULL; i++) {
378
		if (strcmp(authmethods[i]->name, "none") == 0)
379
			continue;
380
		if (authmethods[i]->enabled == NULL ||
381
		    *(authmethods[i]->enabled) == 0)
382
			continue;
383
		if (!auth2_method_allowed(authctxt, authmethods[i]->name,
384
		    NULL))
385
			continue;
386
		if (buffer_len(&b) > 0)
387
			buffer_append(&b, ",", 1);
388
		buffer_append(&b, authmethods[i]->name,
389
		    strlen(authmethods[i]->name));
390
	}
391
	if ((list = sshbuf_dup_string(&b)) == NULL)
392
		fatal("%s: sshbuf_dup_string failed", __func__);
393
	buffer_free(&b);
394
	return list;
395
}
396
397
static Authmethod *
398
authmethod_lookup(Authctxt *authctxt, const char *name)
399
{
400
	int i;
401
402
	if (name != NULL)
403
		for (i = 0; authmethods[i] != NULL; i++)
404
			if (authmethods[i]->enabled != NULL &&
405
			    *(authmethods[i]->enabled) != 0 &&
406
			    strcmp(name, authmethods[i]->name) == 0 &&
407
			    auth2_method_allowed(authctxt,
408
			    authmethods[i]->name, NULL))
409
				return authmethods[i];
410
	debug2("Unrecognized authentication method name: %s",
411
	    name ? name : "NULL");
412
	return NULL;
413
}
414
415
/*
416
 * Check a comma-separated list of methods for validity. Is need_enable is
417
 * non-zero, then also require that the methods are enabled.
418
 * Returns 0 on success or -1 if the methods list is invalid.
419
 */
420
int
421
auth2_methods_valid(const char *_methods, int need_enable)
422
{
423
	char *methods, *omethods, *method, *p;
424
	u_int i, found;
425
	int ret = -1;
426
427
	if (*_methods == '\0') {
428
		error("empty authentication method list");
429
		return -1;
430
	}
431
	omethods = methods = xstrdup(_methods);
432
	while ((method = strsep(&methods, ",")) != NULL) {
433
		for (found = i = 0; !found && authmethods[i] != NULL; i++) {
434
			if ((p = strchr(method, ':')) != NULL)
435
				*p = '\0';
436
			if (strcmp(method, authmethods[i]->name) != 0)
437
				continue;
438
			if (need_enable) {
439
				if (authmethods[i]->enabled == NULL ||
440
				    *(authmethods[i]->enabled) == 0) {
441
					error("Disabled method \"%s\" in "
442
					    "AuthenticationMethods list \"%s\"",
443
					    method, _methods);
444
					goto out;
445
				}
446
			}
447
			found = 1;
448
			break;
449
		}
450
		if (!found) {
451
			error("Unknown authentication method \"%s\" in list",
452
			    method);
453
			goto out;
454
		}
455
	}
456
	ret = 0;
457
 out:
458
	free(omethods);
459
	return ret;
460
}
461
462
/*
463
 * Prune the AuthenticationMethods supplied in the configuration, removing
464
 * any methods lists that include disabled methods. Note that this might
465
 * leave authctxt->num_auth_methods == 0, even when multiple required auth
466
 * has been requested. For this reason, all tests for whether multiple is
467
 * enabled should consult options.num_auth_methods directly.
468
 */
469
int
470
auth2_setup_methods_lists(Authctxt *authctxt)
471
{
472
	u_int i;
473
474
	if (options.num_auth_methods == 0)
475
		return 0;
476
	debug3("%s: checking methods", __func__);
477
	authctxt->auth_methods = xcalloc(options.num_auth_methods,
478
	    sizeof(*authctxt->auth_methods));
479
	authctxt->num_auth_methods = 0;
480
	for (i = 0; i < options.num_auth_methods; i++) {
481
		if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
482
			logit("Authentication methods list \"%s\" contains "
483
			    "disabled method, skipping",
484
			    options.auth_methods[i]);
485
			continue;
486
		}
487
		debug("authentication methods list %d: %s",
488
		    authctxt->num_auth_methods, options.auth_methods[i]);
489
		authctxt->auth_methods[authctxt->num_auth_methods++] =
490
		    xstrdup(options.auth_methods[i]);
491
	}
492
	if (authctxt->num_auth_methods == 0) {
493
		error("No AuthenticationMethods left after eliminating "
494
		    "disabled methods");
495
		return -1;
496
	}
497
	return 0;
498
}
499
500
static int
501
list_starts_with(const char *methods, const char *method,
502
    const char *submethod)
503
{
504
	size_t l = strlen(method);
505
	int match;
506
	const char *p;
507
508
	if (strncmp(methods, method, l) != 0)
509
		return MATCH_NONE;
510
	p = methods + l;
511
	match = MATCH_METHOD;
512
	if (*p == ':') {
513
		if (!submethod)
514
			return MATCH_PARTIAL;
515
		l = strlen(submethod);
516
		p += 1;
517
		if (strncmp(submethod, p, l))
518
			return MATCH_NONE;
519
		p += l;
520
		match = MATCH_BOTH;
521
	}
522
	if (*p != ',' && *p != '\0')
523
		return MATCH_NONE;
524
	return match;
525
}
526
527
/*
528
 * Remove method from the start of a comma-separated list of methods.
529
 * Returns 0 if the list of methods did not start with that method or 1
530
 * if it did.
531
 */
532
static int
533
remove_method(char **methods, const char *method, const char *submethod)
534
{
535
	char *omethods = *methods, *p;
536
	size_t l = strlen(method);
537
	int match;
538
539
	match = list_starts_with(omethods, method, submethod);
540
	if (match != MATCH_METHOD && match != MATCH_BOTH)
541
		return 0;
542
	p = omethods + l;
543
	if (submethod && match == MATCH_BOTH)
544
		p += 1 + strlen(submethod); /* include colon */
545
	if (*p == ',')
546
		p++;
547
	*methods = xstrdup(p);
548
	free(omethods);
549
	return 1;
550
}
551
552
/*
553
 * Called after successful authentication. Will remove the successful method
554
 * from the start of each list in which it occurs. If it was the last method
555
 * in any list, then authentication is deemed successful.
556
 * Returns 1 if the method completed any authentication list or 0 otherwise.
557
 */
558
int
559
auth2_update_methods_lists(Authctxt *authctxt, const char *method,
560
    const char *submethod)
561
{
562
	u_int i, found = 0;
563
564
	debug3("%s: updating methods list after \"%s\"", __func__, method);
565
	for (i = 0; i < authctxt->num_auth_methods; i++) {
566
		if (!remove_method(&(authctxt->auth_methods[i]), method,
567
		    submethod))
568
			continue;
569
		found = 1;
570
		if (*authctxt->auth_methods[i] == '\0') {
571
			debug2("authentication methods list %d complete", i);
572
			return 1;
573
		}
574
		debug3("authentication methods list %d remaining: \"%s\"",
575
		    i, authctxt->auth_methods[i]);
576
	}
577
	/* This should not happen, but would be bad if it did */
578
	if (!found)
579
		fatal("%s: method not in AuthenticationMethods", __func__);
580
	return 0;
581
}
582
583
/* Reset method-specific information */
584
void auth2_authctxt_reset_info(Authctxt *authctxt)
585
{
586
	sshkey_free(authctxt->auth_method_key);
587
	free(authctxt->auth_method_info);
588
	authctxt->auth_method_key = NULL;
589
	authctxt->auth_method_info = NULL;
590
}
591
592
/* Record auth method-specific information for logs */
593
void
594
auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
595
{
596
	va_list ap;
597
        int i;
598
599
	free(authctxt->auth_method_info);
600
	authctxt->auth_method_info = NULL;
601
602
	va_start(ap, fmt);
603
	i = vasprintf(&authctxt->auth_method_info, fmt, ap);
604
	va_end(ap);
605
606
	if (i < 0 || authctxt->auth_method_info == NULL)
607
		fatal("%s: vasprintf failed", __func__);
608
}
609
610
/*
611
 * Records a public key used in authentication. This is used for logging
612
 * and to ensure that the same key is not subsequently accepted again for
613
 * multiple authentication.
614
 */
615
void
616
auth2_record_key(Authctxt *authctxt, int authenticated,
617
    const struct sshkey *key)
618
{
619
	struct sshkey **tmp, *dup;
620
	int r;
621
622
	if ((r = sshkey_demote(key, &dup)) != 0)
623
		fatal("%s: copy key: %s", __func__, ssh_err(r));
624
	sshkey_free(authctxt->auth_method_key);
625
	authctxt->auth_method_key = dup;
626
627
	if (!authenticated)
628
		return;
629
630
	/* If authenticated, make sure we don't accept this key again */
631
	if ((r = sshkey_demote(key, &dup)) != 0)
632
		fatal("%s: copy key: %s", __func__, ssh_err(r));
633
	if (authctxt->nprev_keys >= INT_MAX ||
634
	    (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
635
	    authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
636
		fatal("%s: reallocarray failed", __func__);
637
	authctxt->prev_keys = tmp;
638
	authctxt->prev_keys[authctxt->nprev_keys] = dup;
639
	authctxt->nprev_keys++;
640
641
}
642
643
/* Checks whether a key has already been previously used for authentication */
644
int
645
auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
646
{
647
	u_int i;
648
	char *fp;
649
650
	for (i = 0; i < authctxt->nprev_keys; i++) {
651
		if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
652
			fp = sshkey_fingerprint(authctxt->prev_keys[i],
653
			    options.fingerprint_hash, SSH_FP_DEFAULT);
654
			debug3("%s: key already used: %s %s", __func__,
655
			    sshkey_type(authctxt->prev_keys[i]),
656
			    fp == NULL ? "UNKNOWN" : fp);
657
			free(fp);
658
			return 1;
659
		}
660
	}
661
	return 0;
662
}
663
664
/*
665
 * Updates authctxt->session_info with details of authentication. Should be
666
 * whenever an authentication method succeeds.
667
 */
668
void
669
auth2_update_session_info(Authctxt *authctxt, const char *method,
670
    const char *submethod)
671
{
672
	int r;
673
674
	if (authctxt->session_info == NULL) {
675
		if ((authctxt->session_info = sshbuf_new()) == NULL)
676
			fatal("%s: sshbuf_new", __func__);
677
	}
678
679
	/* Append method[/submethod] */
680
	if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
681
	    method, submethod == NULL ? "" : "/",
682
	    submethod == NULL ? "" : submethod)) != 0)
683
		fatal("%s: append method: %s", __func__, ssh_err(r));
684
685
	/* Append key if present */
686
	if (authctxt->auth_method_key != NULL) {
687
		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
688
		    (r = sshkey_format_text(authctxt->auth_method_key,
689
		    authctxt->session_info)) != 0)
690
			fatal("%s: append key: %s", __func__, ssh_err(r));
691
	}
692
693
	if (authctxt->auth_method_info != NULL) {
694
		/* Ensure no ambiguity here */
695
		if (strchr(authctxt->auth_method_info, '\n') != NULL)
696
			fatal("%s: auth_method_info contains \\n", __func__);
697
		if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
698
		    (r = sshbuf_putf(authctxt->session_info, "%s",
699
		    authctxt->auth_method_info)) != 0) {
700
			fatal("%s: append method info: %s",
701
			    __func__, ssh_err(r));
702
		}
703
	}
704
	if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
705
		fatal("%s: append: %s", __func__, ssh_err(r));
706
}
707