summaryrefslogtreecommitdiffstats
path: root/crypto/openssh/auth-pam.c
blob: ef87bfbfa03913d18da7355ad58f60e1151c8413 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
/*-
 * Copyright (c) 2002 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by ThinkSec AS and
 * NAI Labs, the Security Research Division of Network Associates, Inc.
 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
 * DARPA CHATS research program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org>
 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* Based on $xFreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */
#include "includes.h"
RCSID("$Id: auth-pam.c,v 1.126 2005/07/17 07:18:50 djm Exp $");
RCSID("$FreeBSD$");

#ifdef USE_PAM
#if defined(HAVE_SECURITY_PAM_APPL_H)
#include <security/pam_appl.h>
#elif defined (HAVE_PAM_PAM_APPL_H)
#include <pam/pam_appl.h>
#endif

/* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */
#ifdef PAM_SUN_CODEBASE
# define sshpam_const		/* Solaris, HP-UX, AIX */
#else
# define sshpam_const	const	/* LinuxPAM, OpenPAM */
#endif

#include "auth.h"
#include "auth-pam.h"
#include "buffer.h"
#include "bufaux.h"
#include "canohost.h"
#include "log.h"
#include "monitor_wrap.h"
#include "msg.h"
#include "packet.h"
#include "misc.h"
#include "servconf.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "auth-options.h"

extern ServerOptions options;
extern Buffer loginmsg;
extern int compat20;
extern u_int utmp_len;

/* so we don't silently change behaviour */
#ifdef USE_POSIX_THREADS
# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK"
#endif

/*
 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported
 * and generally a bad idea.  Use at own risk and do not expect support if
 * this breaks.
 */
#ifdef UNSUPPORTED_POSIX_THREADS_HACK
#include <pthread.h>
/*
 * Avoid namespace clash when *not* using pthreads for systems *with*
 * pthreads, which unconditionally define pthread_t via sys/types.h
 * (e.g. Linux)
 */
typedef pthread_t sp_pthread_t;
#else
typedef pid_t sp_pthread_t;
#endif

struct pam_ctxt {
	sp_pthread_t	 pam_thread;
	int		 pam_psock;
	int		 pam_csock;
	int		 pam_done;
};

static void sshpam_free_ctx(void *);
static struct pam_ctxt *cleanup_ctxt;

#ifndef UNSUPPORTED_POSIX_THREADS_HACK
/*
 * Simulate threads with processes.
 */

static int sshpam_thread_status = -1;
static mysig_t sshpam_oldsig;

static void
sshpam_sigchld_handler(int sig)
{
	signal(SIGCHLD, SIG_DFL);
	if (cleanup_ctxt == NULL)
		return;	/* handler called after PAM cleanup, shouldn't happen */
	if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG)
	    <= 0) {
		/* PAM thread has not exitted, privsep slave must have */
		kill(cleanup_ctxt->pam_thread, SIGTERM);
		if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0)
		    <= 0)
			return; /* could not wait */
	}
	if (WIFSIGNALED(sshpam_thread_status) &&
	    WTERMSIG(sshpam_thread_status) == SIGTERM)
		return;	/* terminated by pthread_cancel */
	if (!WIFEXITED(sshpam_thread_status))
		fatal("PAM: authentication thread exited unexpectedly");
	if (WEXITSTATUS(sshpam_thread_status) != 0)
		fatal("PAM: authentication thread exited uncleanly");
}

static void
pthread_exit(void *value __unused)
{
	_exit(0);
}

static int
pthread_create(sp_pthread_t *thread, const void *attr __unused,
    void *(*thread_start)(void *), void *arg)
{
	pid_t pid;
	struct pam_ctxt *ctx = arg;

	sshpam_thread_status = -1;
	switch ((pid = fork())) {
	case -1:
		error("fork(): %s", strerror(errno));
		return (-1);
	case 0:
		close(ctx->pam_psock);
		ctx->pam_psock = -1;
		thread_start(arg);
		_exit(1);
	default:
		*thread = pid;
		close(ctx->pam_csock);
		ctx->pam_csock = -1;
		sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler);
		return (0);
	}
}

static int
pthread_cancel(sp_pthread_t thread)
{
	signal(SIGCHLD, sshpam_oldsig);
	return (kill(thread, SIGTERM));
}

static int
pthread_join(sp_pthread_t thread, void **value __unused)
{
	int status;

	if (sshpam_thread_status != -1)
		return (sshpam_thread_status);
	signal(SIGCHLD, sshpam_oldsig);
	waitpid(thread, &status, 0);
	return (status);
}
#endif


static pam_handle_t *sshpam_handle = NULL;
static int sshpam_err = 0;
static int sshpam_authenticated = 0;
static int sshpam_session_open = 0;
static int sshpam_cred_established = 0;
static int sshpam_account_status = -1;
static char **sshpam_env = NULL;
static Authctxt *sshpam_authctxt = NULL;
static const char *sshpam_password = NULL;
static char badpw[] = "\b\n\r\177INCORRECT";

/* Some PAM implementations don't implement this */
#ifndef HAVE_PAM_GETENVLIST
static char **
pam_getenvlist(pam_handle_t *pamh)
{
	/*
	 * XXX - If necessary, we can still support envrionment passing
	 * for platforms without pam_getenvlist by searching for known
	 * env vars (e.g. KRB5CCNAME) from the PAM environment.
	 */
	 return NULL;
}
#endif

/*
 * Some platforms, notably Solaris, do not enforce password complexity
 * rules during pam_chauthtok() if the real uid of the calling process
 * is 0, on the assumption that it's being called by "passwd" run by root.
 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do
 * the right thing.
 */
#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID
static int
sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags)
{
	int result;

	if (sshpam_authctxt == NULL)
		fatal("PAM: sshpam_authctxt not initialized");
	if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1)
		fatal("%s: setreuid failed: %s", __func__, strerror(errno));
	result = pam_chauthtok(pamh, flags);
	if (setreuid(0, -1) == -1)
		fatal("%s: setreuid failed: %s", __func__, strerror(errno));
	return result;
}
# define pam_chauthtok(a,b)	(sshpam_chauthtok_ruid((a), (b)))
#endif

void
sshpam_password_change_required(int reqd)
{
	debug3("%s %d", __func__, reqd);
	if (sshpam_authctxt == NULL)
		fatal("%s: PAM authctxt not initialized", __func__);
	sshpam_authctxt->force_pwchange = reqd;
	if (reqd) {
		no_port_forwarding_flag |= 2;
		no_agent_forwarding_flag |= 2;
		no_x11_forwarding_flag |= 2;
	} else {
		no_port_forwarding_flag &= ~2;
		no_agent_forwarding_flag &= ~2;
		no_x11_forwarding_flag &= ~2;
	}
}

/* Import regular and PAM environment from subprocess */
static void
import_environments(Buffer *b)
{
	char *env;
	u_int i, num_env;
	int err;

	debug3("PAM: %s entering", __func__);

#ifndef UNSUPPORTED_POSIX_THREADS_HACK
	/* Import variables set by do_pam_account */
	sshpam_account_status = buffer_get_int(b);
	sshpam_password_change_required(buffer_get_int(b));

	/* Import environment from subprocess */
	num_env = buffer_get_int(b);
	sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env));
	debug3("PAM: num env strings %d", num_env);
	for(i = 0; i < num_env; i++)
		sshpam_env[i] = buffer_get_string(b, NULL);

	sshpam_env[num_env] = NULL;

	/* Import PAM environment from subprocess */
	num_env = buffer_get_int(b);
	debug("PAM: num PAM env strings %d", num_env);
	for(i = 0; i < num_env; i++) {
		env = buffer_get_string(b, NULL);

#ifdef HAVE_PAM_PUTENV
		/* Errors are not fatal here */
		if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) {
			error("PAM: pam_putenv: %s",
			    pam_strerror(sshpam_handle, sshpam_err));
		}
#endif
	}
#endif
}

/*
 * Conversation function for authentication thread.
 */
static int
sshpam_thread_conv(int n, sshpam_const struct pam_message **msg,
    struct pam_response **resp, void *data)
{
	Buffer buffer;
	struct pam_ctxt *ctxt;
	struct pam_response *reply;
	int i;

	debug3("PAM: %s entering, %d messages", __func__, n);
	*resp = NULL;

	if (data == NULL) {
		error("PAM: conversation function passed a null context");
		return (PAM_CONV_ERR);
	}
	ctxt = data;
	if (n <= 0 || n > PAM_MAX_NUM_MSG)
		return (PAM_CONV_ERR);

	if ((reply = malloc(n * sizeof(*reply))) == NULL)
		return (PAM_CONV_ERR);
	memset(reply, 0, n * sizeof(*reply));

	buffer_init(&buffer);
	for (i = 0; i < n; ++i) {
		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
		case PAM_PROMPT_ECHO_OFF:
			buffer_put_cstring(&buffer,
			    PAM_MSG_MEMBER(msg, i, msg));
			if (ssh_msg_send(ctxt->pam_csock,
			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
				goto fail;
			if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
				goto fail;
			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
				goto fail;
			reply[i].resp = buffer_get_string(&buffer, NULL);
			break;
		case PAM_PROMPT_ECHO_ON:
			buffer_put_cstring(&buffer,
			    PAM_MSG_MEMBER(msg, i, msg));
			if (ssh_msg_send(ctxt->pam_csock,
			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
				goto fail;
			if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1)
				goto fail;
			if (buffer_get_char(&buffer) != PAM_AUTHTOK)
				goto fail;
			reply[i].resp = buffer_get_string(&buffer, NULL);
			break;
		case PAM_ERROR_MSG:
			buffer_put_cstring(&buffer,
			    PAM_MSG_MEMBER(msg, i, msg));
			if (ssh_msg_send(ctxt->pam_csock,
			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
				goto fail;
			break;
		case PAM_TEXT_INFO:
			buffer_put_cstring(&buffer,
			    PAM_MSG_MEMBER(msg, i, msg));
			if (ssh_msg_send(ctxt->pam_csock,
			    PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1)
				goto fail;
			break;
		default:
			goto fail;
		}
		buffer_clear(&buffer);
	}
	buffer_free(&buffer);
	*resp = reply;
	return (PAM_SUCCESS);

 fail:
	for(i = 0; i < n; i++) {
		if (reply[i].resp != NULL)
			xfree(reply[i].resp);
	}
	xfree(reply);
	buffer_free(&buffer);
	return (PAM_CONV_ERR);
}

/*
 * Authentication thread.
 */
static void *
sshpam_thread(void *ctxtp)
{
	struct pam_ctxt *ctxt = ctxtp;
	Buffer buffer;
	struct pam_conv sshpam_conv;
	int flags = (options.permit_empty_passwd == 0 ?
	    PAM_DISALLOW_NULL_AUTHTOK : 0);
#ifndef UNSUPPORTED_POSIX_THREADS_HACK
	extern char **environ;
	char **env_from_pam;
	u_int i;
	const char *pam_user;
	const char **ptr_pam_user = &pam_user;

	pam_get_item(sshpam_handle, PAM_USER,
	    (sshpam_const void **)ptr_pam_user);
	environ[0] = NULL;

	if (sshpam_authctxt != NULL) {
		setproctitle("%s [pam]",
		    sshpam_authctxt->valid ? pam_user : "unknown");
	}
#endif

	sshpam_conv.conv = sshpam_thread_conv;
	sshpam_conv.appdata_ptr = ctxt;

	if (sshpam_authctxt == NULL)
		fatal("%s: PAM authctxt not initialized", __func__);

	buffer_init(&buffer);
	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
	    (const void *)&sshpam_conv);
	if (sshpam_err != PAM_SUCCESS)
		goto auth_fail;
	sshpam_err = pam_authenticate(sshpam_handle, flags);
	if (sshpam_err != PAM_SUCCESS)
		goto auth_fail;

	if (compat20) {
		if (!do_pam_account())
			goto auth_fail;
		if (sshpam_authctxt->force_pwchange) {
			sshpam_err = pam_chauthtok(sshpam_handle,
			    PAM_CHANGE_EXPIRED_AUTHTOK);
			if (sshpam_err != PAM_SUCCESS)
				goto auth_fail;
			sshpam_password_change_required(0);
		}
	}

	buffer_put_cstring(&buffer, "OK");

#ifndef UNSUPPORTED_POSIX_THREADS_HACK
	/* Export variables set by do_pam_account */
	buffer_put_int(&buffer, sshpam_account_status);
	buffer_put_int(&buffer, sshpam_authctxt->force_pwchange);

	/* Export any environment strings set in child */
	for(i = 0; environ[i] != NULL; i++)
		; /* Count */
	buffer_put_int(&buffer, i);
	for(i = 0; environ[i] != NULL; i++)
		buffer_put_cstring(&buffer, environ[i]);

	/* Export any environment strings set by PAM in child */
	env_from_pam = pam_getenvlist(sshpam_handle);
	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
		; /* Count */
	buffer_put_int(&buffer, i);
	for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++)
		buffer_put_cstring(&buffer, env_from_pam[i]);
#endif /* UNSUPPORTED_POSIX_THREADS_HACK */

	/* XXX - can't do much about an error here */
	ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer);
	buffer_free(&buffer);
	pthread_exit(NULL);

 auth_fail:
	buffer_put_cstring(&buffer,
	    pam_strerror(sshpam_handle, sshpam_err));
	/* XXX - can't do much about an error here */
	ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer);
	buffer_free(&buffer);
	pthread_exit(NULL);

	return (NULL); /* Avoid warning for non-pthread case */
}

void
sshpam_thread_cleanup(void)
{
	struct pam_ctxt *ctxt = cleanup_ctxt;

	debug3("PAM: %s entering", __func__);
	if (ctxt != NULL && ctxt->pam_thread != 0) {
		pthread_cancel(ctxt->pam_thread);
		pthread_join(ctxt->pam_thread, NULL);
		close(ctxt->pam_psock);
		close(ctxt->pam_csock);
		memset(ctxt, 0, sizeof(*ctxt));
		cleanup_ctxt = NULL;
	}
}

static int
sshpam_null_conv(int n, sshpam_const struct pam_message **msg,
    struct pam_response **resp, void *data)
{
	debug3("PAM: %s entering, %d messages", __func__, n);
	return (PAM_CONV_ERR);
}

static struct pam_conv null_conv = { sshpam_null_conv, NULL };

static int
sshpam_store_conv(int n, sshpam_const struct pam_message **msg,
    struct pam_response **resp, void *data)
{
	struct pam_response *reply;
	int i;
	size_t len;

	debug3("PAM: %s called with %d messages", __func__, n);
	*resp = NULL;

	if (n <= 0 || n > PAM_MAX_NUM_MSG)
		return (PAM_CONV_ERR);

	if ((reply = malloc(n * sizeof(*reply))) == NULL)
		return (PAM_CONV_ERR);
	memset(reply, 0, n * sizeof(*reply));

	for (i = 0; i < n; ++i) {
		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
		case PAM_ERROR_MSG:
		case PAM_TEXT_INFO:
			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
			buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len);
			buffer_append(&loginmsg, "\n", 1 );
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		default:
			goto fail;
		}
	}
	*resp = reply;
	return (PAM_SUCCESS);

 fail:
	for(i = 0; i < n; i++) {
		if (reply[i].resp != NULL)
			xfree(reply[i].resp);
	}
	xfree(reply);
	return (PAM_CONV_ERR);
}

static struct pam_conv store_conv = { sshpam_store_conv, NULL };

void
sshpam_cleanup(void)
{
	debug("PAM: cleanup");
	if (sshpam_handle == NULL)
		return;
	pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv);
	if (sshpam_cred_established) {
		pam_setcred(sshpam_handle, PAM_DELETE_CRED);
		sshpam_cred_established = 0;
	}
	if (sshpam_session_open) {
		pam_close_session(sshpam_handle, PAM_SILENT);
		sshpam_session_open = 0;
	}
	sshpam_authenticated = 0;
	pam_end(sshpam_handle, sshpam_err);
	sshpam_handle = NULL;
}

static int
sshpam_init(Authctxt *authctxt)
{
	extern char *__progname;
	const char *pam_rhost, *pam_user, *user = authctxt->user;
	const char **ptr_pam_user = &pam_user;

	if (sshpam_handle != NULL) {
		/* We already have a PAM context; check if the user matches */
		sshpam_err = pam_get_item(sshpam_handle,
		    PAM_USER, (sshpam_const void **)ptr_pam_user);
		if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0)
			return (0);
		pam_end(sshpam_handle, sshpam_err);
		sshpam_handle = NULL;
	}
	debug("PAM: initializing for \"%s\"", user);
	sshpam_err =
	    pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle);
	sshpam_authctxt = authctxt;

	if (sshpam_err != PAM_SUCCESS) {
		pam_end(sshpam_handle, sshpam_err);
		sshpam_handle = NULL;
		return (-1);
	}
	pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns);
	debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost);
	sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost);
	if (sshpam_err != PAM_SUCCESS) {
		pam_end(sshpam_handle, sshpam_err);
		sshpam_handle = NULL;
		return (-1);
	}
#ifdef PAM_TTY_KLUDGE
	/*
	 * Some silly PAM modules (e.g. pam_time) require a TTY to operate.
	 * sshd doesn't set the tty until too late in the auth process and
	 * may not even set one (for tty-less connections)
	 */
	debug("PAM: setting PAM_TTY to \"ssh\"");
	sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh");
	if (sshpam_err != PAM_SUCCESS) {
		pam_end(sshpam_handle, sshpam_err);
		sshpam_handle = NULL;
		return (-1);
	}
#endif
	return (0);
}

static void *
sshpam_init_ctx(Authctxt *authctxt)
{
	struct pam_ctxt *ctxt;
	int socks[2];

	debug3("PAM: %s entering", __func__);
	/* Refuse to start if we don't have PAM enabled */
	if (!options.use_pam)
		return NULL;

	/* Initialize PAM */
	if (sshpam_init(authctxt) == -1) {
		error("PAM: initialization failed");
		return (NULL);
	}

	ctxt = xmalloc(sizeof *ctxt);
	memset(ctxt, 0, sizeof(*ctxt));

	/* Start the authentication thread */
	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
		error("PAM: failed create sockets: %s", strerror(errno));
		xfree(ctxt);
		return (NULL);
	}
	ctxt->pam_psock = socks[0];
	ctxt->pam_csock = socks[1];
	if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) {
		error("PAM: failed to start authentication thread: %s",
		    strerror(errno));
		close(socks[0]);
		close(socks[1]);
		xfree(ctxt);
		return (NULL);
	}
	cleanup_ctxt = ctxt;
	return (ctxt);
}

static int
sshpam_query(void *ctx, char **name, char **info,
    u_int *num, char ***prompts, u_int **echo_on)
{
	Buffer buffer;
	struct pam_ctxt *ctxt = ctx;
	size_t plen;
	u_char type;
	char *msg;
	size_t len, mlen;

	debug3("PAM: %s entering", __func__);
	buffer_init(&buffer);
	*name = xstrdup("");
	*info = xstrdup("");
	*prompts = xmalloc(sizeof(char *));
	**prompts = NULL;
	plen = 0;
	*echo_on = xmalloc(sizeof(u_int));
	while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) {
		type = buffer_get_char(&buffer);
		msg = buffer_get_string(&buffer, NULL);
		mlen = strlen(msg);
		switch (type) {
		case PAM_PROMPT_ECHO_ON:
		case PAM_PROMPT_ECHO_OFF:
			*num = 1;
			len = plen + mlen + 1;
			**prompts = xrealloc(**prompts, len);
			strlcpy(**prompts + plen, msg, len - plen);
			plen += mlen;
			**echo_on = (type == PAM_PROMPT_ECHO_ON);
			xfree(msg);
			return (0);
		case PAM_ERROR_MSG:
		case PAM_TEXT_INFO:
			/* accumulate messages */
			len = plen + mlen + 2;
			**prompts = xrealloc(**prompts, len);
			strlcpy(**prompts + plen, msg, len - plen);
			plen += mlen;
			strlcat(**prompts + plen, "\n", len - plen);
			plen++;
			xfree(msg);
			break;
		case PAM_SUCCESS:
		case PAM_AUTH_ERR:
			if (**prompts != NULL) {
				/* drain any accumulated messages */
				debug("PAM: %s", **prompts);
				buffer_append(&loginmsg, **prompts,
				    strlen(**prompts));
				xfree(**prompts);
				**prompts = NULL;
			}
			if (type == PAM_SUCCESS) {
				if (!sshpam_authctxt->valid ||
				    (sshpam_authctxt->pw->pw_uid == 0 &&
				    options.permit_root_login != PERMIT_YES))
					fatal("Internal error: PAM auth "
					    "succeeded when it should have "
					    "failed");
				import_environments(&buffer);
				*num = 0;
				**echo_on = 0;
				ctxt->pam_done = 1;
				xfree(msg);
				return (0);
			}
			error("PAM: %s for %s%.100s from %.100s", msg,
			    sshpam_authctxt->valid ? "" : "illegal user ",
			    sshpam_authctxt->user,
			    get_remote_name_or_ip(utmp_len, options.use_dns));
			/* FALLTHROUGH */
		default:
			*num = 0;
			**echo_on = 0;
			xfree(msg);
			ctxt->pam_done = -1;
			return (-1);
		}
	}
	return (-1);
}

/* XXX - see also comment in auth-chall.c:verify_response */
static int
sshpam_respond(void *ctx, u_int num, char **resp)
{
	Buffer buffer;
	struct pam_ctxt *ctxt = ctx;

	debug2("PAM: %s entering, %d responses", __func__, num);
	switch (ctxt->pam_done) {
	case 1:
		sshpam_authenticated = 1;
		return (0);
	case 0:
		break;
	default:
		return (-1);
	}
	if (num != 1) {
		error("PAM: expected one response, got %u", num);
		return (-1);
	}
	buffer_init(&buffer);
	if (sshpam_authctxt->valid &&
	    (sshpam_authctxt->pw->pw_uid != 0 ||
	    options.permit_root_login == PERMIT_YES))
		buffer_put_cstring(&buffer, *resp);
	else
		buffer_put_cstring(&buffer, badpw);
	if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) {
		buffer_free(&buffer);
		return (-1);
	}
	buffer_free(&buffer);
	return (1);
}

static void
sshpam_free_ctx(void *ctxtp)
{
	struct pam_ctxt *ctxt = ctxtp;

	debug3("PAM: %s entering", __func__);
	sshpam_thread_cleanup();
	xfree(ctxt);
	/*
	 * We don't call sshpam_cleanup() here because we may need the PAM
	 * handle at a later stage, e.g. when setting up a session.  It's
	 * still on the cleanup list, so pam_end() *will* be called before
	 * the server process terminates.
	 */
}

KbdintDevice sshpam_device = {
	"pam",
	sshpam_init_ctx,
	sshpam_query,
	sshpam_respond,
	sshpam_free_ctx
};

KbdintDevice mm_sshpam_device = {
	"pam",
	mm_sshpam_init_ctx,
	mm_sshpam_query,
	mm_sshpam_respond,
	mm_sshpam_free_ctx
};

/*
 * This replaces auth-pam.c
 */
void
start_pam(Authctxt *authctxt)
{
	if (!options.use_pam)
		fatal("PAM: initialisation requested when UsePAM=no");

	if (sshpam_init(authctxt) == -1)
		fatal("PAM: initialisation failed");
}

void
finish_pam(void)
{
	sshpam_cleanup();
}

u_int
do_pam_account(void)
{
	debug("%s: called", __func__);
	if (sshpam_account_status != -1)
		return (sshpam_account_status);

	sshpam_err = pam_acct_mgmt(sshpam_handle, 0);
	debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err,
	    pam_strerror(sshpam_handle, sshpam_err));

	if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) {
		sshpam_account_status = 0;
		return (sshpam_account_status);
	}

	if (sshpam_err == PAM_NEW_AUTHTOK_REQD)
		sshpam_password_change_required(1);

	sshpam_account_status = 1;
	return (sshpam_account_status);
}

void
do_pam_set_tty(const char *tty)
{
	if (tty != NULL) {
		debug("PAM: setting PAM_TTY to \"%s\"", tty);
		sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty);
		if (sshpam_err != PAM_SUCCESS)
			fatal("PAM: failed to set PAM_TTY: %s",
			    pam_strerror(sshpam_handle, sshpam_err));
	}
}

void
do_pam_setcred(int init)
{
	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
	    (const void *)&store_conv);
	if (sshpam_err != PAM_SUCCESS)
		fatal("PAM: failed to set PAM_CONV: %s",
		    pam_strerror(sshpam_handle, sshpam_err));
	if (init) {
		debug("PAM: establishing credentials");
		sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED);
	} else {
		debug("PAM: reinitializing credentials");
		sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED);
	}
	if (sshpam_err == PAM_SUCCESS) {
		sshpam_cred_established = 1;
		return;
	}
	if (sshpam_authenticated)
		fatal("PAM: pam_setcred(): %s",
		    pam_strerror(sshpam_handle, sshpam_err));
	else
		debug("PAM: pam_setcred(): %s",
		    pam_strerror(sshpam_handle, sshpam_err));
}

static int
sshpam_tty_conv(int n, sshpam_const struct pam_message **msg,
    struct pam_response **resp, void *data)
{
	char input[PAM_MAX_MSG_SIZE];
	struct pam_response *reply;
	int i;

	debug3("PAM: %s called with %d messages", __func__, n);

	*resp = NULL;

	if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO))
		return (PAM_CONV_ERR);

	if ((reply = malloc(n * sizeof(*reply))) == NULL)
		return (PAM_CONV_ERR);
	memset(reply, 0, n * sizeof(*reply));

	for (i = 0; i < n; ++i) {
		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
		case PAM_PROMPT_ECHO_OFF:
			reply[i].resp =
			    read_passphrase(PAM_MSG_MEMBER(msg, i, msg),
			    RP_ALLOW_STDIN);
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		case PAM_PROMPT_ECHO_ON:
			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
			fgets(input, sizeof input, stdin);
			if ((reply[i].resp = strdup(input)) == NULL)
				goto fail;
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		case PAM_ERROR_MSG:
		case PAM_TEXT_INFO:
			fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg));
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		default:
			goto fail;
		}
	}
	*resp = reply;
	return (PAM_SUCCESS);

 fail:
	for(i = 0; i < n; i++) {
		if (reply[i].resp != NULL)
			xfree(reply[i].resp);
	}
	xfree(reply);
	return (PAM_CONV_ERR);
}

static struct pam_conv tty_conv = { sshpam_tty_conv, NULL };

/*
 * XXX this should be done in the authentication phase, but ssh1 doesn't
 * support that
 */
void
do_pam_chauthtok(void)
{
	if (use_privsep)
		fatal("Password expired (unable to change with privsep)");
	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
	    (const void *)&tty_conv);
	if (sshpam_err != PAM_SUCCESS)
		fatal("PAM: failed to set PAM_CONV: %s",
		    pam_strerror(sshpam_handle, sshpam_err));
	debug("PAM: changing password");
	sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK);
	if (sshpam_err != PAM_SUCCESS)
		fatal("PAM: pam_chauthtok(): %s",
		    pam_strerror(sshpam_handle, sshpam_err));
}

void
do_pam_session(void)
{
	debug3("PAM: opening session");
	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
	    (const void *)&store_conv);
	if (sshpam_err != PAM_SUCCESS)
		fatal("PAM: failed to set PAM_CONV: %s",
		    pam_strerror(sshpam_handle, sshpam_err));
	sshpam_err = pam_open_session(sshpam_handle, 0);
	if (sshpam_err == PAM_SUCCESS)
		sshpam_session_open = 1;
	else {
		sshpam_session_open = 0;
		disable_forwarding();
		error("PAM: pam_open_session(): %s",
		    pam_strerror(sshpam_handle, sshpam_err));
	}

}

int
is_pam_session_open(void)
{
	return sshpam_session_open;
}

/*
 * Set a PAM environment string. We need to do this so that the session
 * modules can handle things like Kerberos/GSI credentials that appear
 * during the ssh authentication process.
 */
int
do_pam_putenv(char *name, char *value)
{
	int ret = 1;
#ifdef HAVE_PAM_PUTENV
	char *compound;
	size_t len;

	len = strlen(name) + strlen(value) + 2;
	compound = xmalloc(len);

	snprintf(compound, len, "%s=%s", name, value);
	ret = pam_putenv(sshpam_handle, compound);
	xfree(compound);
#endif

	return (ret);
}

char **
fetch_pam_child_environment(void)
{
	return sshpam_env;
}

char **
fetch_pam_environment(void)
{
	return (pam_getenvlist(sshpam_handle));
}

void
free_pam_environment(char **env)
{
	char **envp;

	if (env == NULL)
		return;

	for (envp = env; *envp; envp++)
		xfree(*envp);
	xfree(env);
}

/*
 * "Blind" conversation function for password authentication.  Assumes that
 * echo-off prompts are for the password and stores messages for later
 * display.
 */
static int
sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg,
    struct pam_response **resp, void *data)
{
	struct pam_response *reply;
	int i;
	size_t len;

	debug3("PAM: %s called with %d messages", __func__, n);

	*resp = NULL;

	if (n <= 0 || n > PAM_MAX_NUM_MSG)
		return (PAM_CONV_ERR);

	if ((reply = malloc(n * sizeof(*reply))) == NULL)
		return (PAM_CONV_ERR);
	memset(reply, 0, n * sizeof(*reply));

	for (i = 0; i < n; ++i) {
		switch (PAM_MSG_MEMBER(msg, i, msg_style)) {
		case PAM_PROMPT_ECHO_OFF:
			if (sshpam_password == NULL)
				goto fail;
			if ((reply[i].resp = strdup(sshpam_password)) == NULL)
				goto fail;
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		case PAM_ERROR_MSG:
		case PAM_TEXT_INFO:
			len = strlen(PAM_MSG_MEMBER(msg, i, msg));
			if (len > 0) {
				buffer_append(&loginmsg,
				    PAM_MSG_MEMBER(msg, i, msg), len);
				buffer_append(&loginmsg, "\n", 1);
			}
			if ((reply[i].resp = strdup("")) == NULL)
				goto fail;
			reply[i].resp_retcode = PAM_SUCCESS;
			break;
		default:
			goto fail;
		}
	}
	*resp = reply;
	return (PAM_SUCCESS);

 fail:
	for(i = 0; i < n; i++) {
		if (reply[i].resp != NULL)
			xfree(reply[i].resp);
	}
	xfree(reply);
	return (PAM_CONV_ERR);
}

static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL };

/*
 * Attempt password authentication via PAM
 */
int
sshpam_auth_passwd(Authctxt *authctxt, const char *password)
{
	int flags = (options.permit_empty_passwd == 0 ?
	    PAM_DISALLOW_NULL_AUTHTOK : 0);

	if (!options.use_pam || sshpam_handle == NULL)
		fatal("PAM: %s called when PAM disabled or failed to "
		    "initialise.", __func__);

	sshpam_password = password;
	sshpam_authctxt = authctxt;

	/*
	 * If the user logging in is invalid, or is root but is not permitted
	 * by PermitRootLogin, use an invalid password to prevent leaking
	 * information via timing (eg if the PAM config has a delay on fail).
	 */
	if (!authctxt->valid || (authctxt->pw->pw_uid == 0 &&
	    options.permit_root_login != PERMIT_YES))
		sshpam_password = badpw;

	sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
	    (const void *)&passwd_conv);
	if (sshpam_err != PAM_SUCCESS)
		fatal("PAM: %s: failed to set PAM_CONV: %s", __func__,
		    pam_strerror(sshpam_handle, sshpam_err));

	sshpam_err = pam_authenticate(sshpam_handle, flags);
	sshpam_password = NULL;
	if (sshpam_err == PAM_SUCCESS && authctxt->valid) {
		debug("PAM: password authentication accepted for %.100s",
		    authctxt->user);
		return 1;
	} else {
		debug("PAM: password authentication failed for %.100s: %s",
		    authctxt->valid ? authctxt->user : "an illegal user",
		    pam_strerror(sshpam_handle, sshpam_err));
		return 0;
	}
}
#endif /* USE_PAM */
OpenPOWER on IntegriCloud