summaryrefslogtreecommitdiffstats
path: root/src/login.c
blob: 00508cd5b9b0f9e7e1d779ef121ac56fa8de9d27 (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
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
/*
 * Copyright (c) 1989 - 1994, Julianne Frances Haugh
 * Copyright (c) 1996 - 2001, Marek Michałkiewicz
 * Copyright (c) 2001 - 2006, Tomasz Kłoczko
 * Copyright (c) 2007 - 2012, Nicolas François
 * All rights reserved.
 *
 * 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.
 * 3. The name of the copyright holders or contributors may not be used to
 *    endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * HOLDERS 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.
 */

#include <config.h>

#ident "$Id$"

#include <errno.h>
#include <grp.h>
#ifndef USE_PAM
#include <lastlog.h>
#endif				/* !USE_PAM */
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <assert.h>
#include "defines.h"
#include "faillog.h"
#include "failure.h"
#include "getdef.h"
#include "prototypes.h"
#include "pwauth.h"
/*@-exitarg@*/
#include "exitcodes.h"

#ifdef USE_PAM
#include "pam_defs.h"

static pam_handle_t *pamh = NULL;

#define PAM_FAIL_CHECK if (retcode != PAM_SUCCESS) { \
	fprintf(stderr,"\n%s\n",pam_strerror(pamh, retcode)); \
	SYSLOG((LOG_ERR,"%s",pam_strerror(pamh, retcode))); \
	(void) pam_end(pamh, retcode); \
	exit(1); \
   }
#define PAM_END { retcode = pam_close_session(pamh,0); \
		(void) pam_end(pamh,retcode); }

#endif				/* USE_PAM */

#ifndef USE_PAM
/*
 * Needed for MkLinux DR1/2/2.1 - J.
 */
#ifndef LASTLOG_FILE
#define LASTLOG_FILE "/var/log/lastlog"
#endif
#endif				/* !USE_PAM */

/*
 * Global variables
 */
const char *Prog;

static const char *hostname = "";
static /*@null@*/ /*@only@*/char *username = NULL;
static int reason = PW_LOGIN;

#ifndef USE_PAM
static struct lastlog ll;
#endif				/* !USE_PAM */
static bool pflg = false;
static bool fflg = false;

#ifdef RLOGIN
static bool rflg = false;
#else				/* RLOGIN */
#define rflg false
#endif				/* !RLOGIN */
static bool hflg = false;
static bool preauth_flag = false;

static bool amroot;
static char tmsg[256];

/*
 * External identifiers.
 */

extern char **newenvp;
extern size_t newenvc;
extern char **environ;

#ifndef	ALARM
#define	ALARM	60
#endif

#ifndef	RETRIES
#define	RETRIES	3
#endif

/* local function prototypes */
static void usage (void);
static void setup_tty (void);
static void process_flags (int argc, char *const *argv);
static /*@observer@*/const char *get_failent_user (/*@returned@*/const char *user);
static void update_utmp (const char *user,
                         const char *tty,
                         const char *host,
#ifdef USE_UTMPX
                         /*@null@*/const struct utmpx *utent
#else
                         /*@null@*/const struct utmp *utent
#endif
			);

#ifndef USE_PAM
static struct faillog faillog;

static void bad_time_notify (void);
static void check_nologin (bool login_to_root);
#else
static void get_pam_user (char **ptr_pam_user);
#endif

static void init_env (void);
static RETSIGTYPE alarm_handler (int);

/*
 * usage - print login command usage and exit
 *
 * login [ name ]
 * login -r hostname	(for rlogind)
 * login -h hostname	(for telnetd, etc.)
 * login -f name	(for pre-authenticated login: datakit, xterm, etc.)
 */
static void usage (void)
{
	fprintf (stderr, _("Usage: %s [-p] [name]\n"), Prog);
	if (!amroot) {
		exit (1);
	}
	fprintf (stderr, _("       %s [-p] [-h host] [-f name]\n"), Prog);
#ifdef RLOGIN
	fprintf (stderr, _("       %s [-p] -r host\n"), Prog);
#endif				/* RLOGIN */
	exit (1);
}

static void setup_tty (void)
{
	TERMIO termio;

	if (GTTY (0, &termio) == 0) {	/* get terminal characteristics */
		int erasechar;
		int killchar;

		/*
		 * Add your favorite terminal modes here ...
		 */
		termio.c_lflag |= ISIG | ICANON | ECHO | ECHOE;
		termio.c_iflag |= ICRNL;

#if defined(ECHOKE) && defined(ECHOCTL)
		termio.c_lflag |= ECHOKE | ECHOCTL;
#endif
#if defined(ECHOPRT) && defined(NOFLSH) && defined(TOSTOP)
		termio.c_lflag &= ~(ECHOPRT | NOFLSH | TOSTOP);
#endif
#ifdef ONLCR
		termio.c_oflag |= ONLCR;
#endif

		/* leave these values unchanged if not specified in login.defs */
		erasechar = getdef_num ("ERASECHAR", (int) termio.c_cc[VERASE]);
		killchar = getdef_num ("KILLCHAR", (int) termio.c_cc[VKILL]);
		termio.c_cc[VERASE] = (cc_t) erasechar;
		termio.c_cc[VKILL] = (cc_t) killchar;
		/* Make sure the values were valid.
		 * getdef_num cannot validate this.
		 */
		if (erasechar != (int) termio.c_cc[VERASE]) {
			fprintf (stderr,
			         _("configuration error - cannot parse %s value: '%d'"),
			         "ERASECHAR", erasechar);
			exit (1);
		}
		if (killchar != (int) termio.c_cc[VKILL]) {
			fprintf (stderr,
			         _("configuration error - cannot parse %s value: '%d'"),
			         "KILLCHAR", killchar);
			exit (1);
		}

		/*
		 * ttymon invocation prefers this, but these settings
		 * won't come into effect after the first username login 
		 */
		(void) STTY (0, &termio);
	}
}


#ifndef USE_PAM
/*
 * Tell the user that this is not the right time to login at this tty
 */
static void bad_time_notify (void)
{
	(void) puts (_("Invalid login time"));
	(void) fflush (stdout);
}

static void check_nologin (bool login_to_root)
{
	const char *fname;

	/*
	 * Check to see if system is turned off for non-root users.
	 * This would be useful to prevent users from logging in
	 * during system maintenance. We make sure the message comes
	 * out for root so she knows to remove the file if she's
	 * forgotten about it ...
	 */
	fname = getdef_str ("NOLOGINS_FILE");
	if ((NULL != fname) && (access (fname, F_OK) == 0)) {
		FILE *nlfp;

		/*
		 * Cat the file if it can be opened, otherwise just
		 * print a default message
		 */
		nlfp = fopen (fname, "r");
		if (NULL != nlfp) {
			int c;
			while ((c = getc (nlfp)) != EOF) {
				if (c == '\n') {
					(void) putchar ('\r');
				}

				(void) putchar (c);
			}
			(void) fflush (stdout);
			(void) fclose (nlfp);
		} else {
			(void) puts (_("\nSystem closed for routine maintenance"));
		}
		/*
		 * Non-root users must exit. Root gets the message, but
		 * gets to login.
		 */

		if (!login_to_root) {
			closelog ();
			exit (0);
		}
		(void) puts (_("\n[Disconnect bypassed -- root login allowed.]"));
	}
}
#endif				/* !USE_PAM */

static void process_flags (int argc, char *const *argv)
{
	int arg;
	int flag;

	/*
	 * Check the flags for proper form. Every argument starting with
	 * "-" must be exactly two characters long. This closes all the
	 * clever rlogin, telnet, and getty holes.
	 */
	for (arg = 1; arg < argc; arg++) {
		if (argv[arg][0] == '-' && strlen (argv[arg]) > 2) {
			usage ();
		}
		if (strcmp(argv[arg], "--") == 0) {
			break; /* stop checking on a "--" */
		}
	}

	/*
	 * Process options.
	 */
	while ((flag = getopt (argc, argv, "d:fh:pr:")) != EOF) {
		switch (flag) {
		case 'd':
			/* "-d device" ignored for compatibility */
			break;
		case 'f':
			fflg = true;
			break;
		case 'h':
			hflg = true;
			hostname = optarg;
			reason = PW_TELNET;
			break;
#ifdef	RLOGIN
		case 'r':
			rflg = true;
			hostname = optarg;
			reason = PW_RLOGIN;
			break;
#endif				/* RLOGIN */
		case 'p':
			pflg = true;
			break;
		default:
			usage ();
		}
	}

#ifdef RLOGIN
	/*
	 * Neither -h nor -f should be combined with -r.
	 */

	if (rflg && (hflg || fflg)) {
		usage ();
	}
#endif				/* RLOGIN */

	/*
	 * Allow authentication bypass only if real UID is zero.
	 */

	if ((rflg || fflg || hflg) && !amroot) {
		fprintf (stderr, _("%s: Permission denied.\n"), Prog);
		exit (1);
	}

	/*
	 *  Get the user name.
	 */
	if (optind < argc) {
		assert (NULL == username);
		username = xstrdup (argv[optind]);
		strzero (argv[optind]);
		++optind;
	}

#ifdef	RLOGIN
	if (rflg && (NULL != username)) {
		usage ();
	}
#endif				/* RLOGIN */
	if (fflg && (NULL == username)) {
		usage ();
	}

}


static void init_env (void)
{
#ifndef USE_PAM
	const char *cp;
#endif
	char *tmp;

	tmp = getenv ("LANG");
	if (NULL != tmp) {
		addenv ("LANG", tmp);
	}

	/*
	 * Add the timezone environmental variable so that time functions
	 * work correctly.
	 */
	tmp = getenv ("TZ");
	if (NULL != tmp) {
		addenv ("TZ", tmp);
	}
#ifndef USE_PAM
	else {
		cp = getdef_str ("ENV_TZ");
		if (NULL != cp) {
			addenv (('/' == *cp) ? tz (cp) : cp, NULL);
		}
	}
#endif				/* !USE_PAM */
	/* 
	 * Add the clock frequency so that profiling commands work
	 * correctly.
	 */
	tmp = getenv ("HZ");
	if (NULL != tmp) {
		addenv ("HZ", tmp);
	}
#ifndef USE_PAM
	else {
		cp = getdef_str ("ENV_HZ");
		if (NULL != cp) {
			addenv (cp, NULL);
		}
	}
#endif				/* !USE_PAM */
}


static RETSIGTYPE alarm_handler (unused int sig)
{
	write (STDERR_FILENO, tmsg, strlen (tmsg));
	_exit (0);
}

#ifdef USE_PAM
/*
 * get_pam_user - Get the username according to PAM
 *
 * ptr_pam_user shall point to a malloc'ed string (or NULL).
 */
static void get_pam_user (char **ptr_pam_user)
{
	int retcode;
	void *ptr_user;

	assert (NULL != ptr_pam_user);

	retcode = pam_get_item (pamh, PAM_USER, (const void **)&ptr_user);
	PAM_FAIL_CHECK;

	if (NULL != *ptr_pam_user) {
		free (*ptr_pam_user);
	}
	if (NULL != ptr_user) {
		*ptr_pam_user = xstrdup ((const char *)ptr_user);
	} else {
		*ptr_pam_user = NULL;
	}
}
#endif

/*
 * get_failent_user - Return a string that can be used to log failure
 *                    from an user.
 *
 * This will be either the user argument, or "UNKNOWN".
 *
 * It is quite common to mistyped the password for username, and passwords
 * should not be logged.
 */
static /*@observer@*/const char *get_failent_user (/*@returned@*/const char *user)
{
	const char *failent_user = "UNKNOWN";
	bool log_unkfail_enab = getdef_bool("LOG_UNKFAIL_ENAB");

	if ((NULL != user) && ('\0' != user[0])) {
		if (   log_unkfail_enab
		    || (getpwnam (user) != NULL)) {
			failent_user = user;
		}
	}

	return failent_user;
}

/*
 * update_utmp - Update or create an utmp entry in utmp, wtmp, utmpw, and
 *               wtmpx
 *
 *	utent should be the utmp entry returned by get_current_utmp (or
 *	NULL).
 */
static void update_utmp (const char *user,
                         const char *tty,
                         const char *host,
#ifdef USE_UTMPX
                         /*@null@*/const struct utmpx *utent
#else
                         /*@null@*/const struct utmp *utent
#endif
			 )
{
#ifdef USE_UTMPX
	struct utmpx *utx = prepare_utmpx (user, tty, host, utent);
#else
	struct utmp  *ut  = prepare_utmp  (user, tty, host, utent);
#endif				/* USE_UTMPX */

#ifndef USE_UTMPX
	(void) setutmp  (ut);	/* make entry in the utmp & wtmp files */
	free (ut);
#else
	(void) setutmpx (utx);	/* make entry in the utmpx & wtmpx files */
	free (utx);
#endif				/* USE_UTMPX */
}

/*
 * login - create a new login session for a user
 *
 *	login is typically called by getty as the second step of a
 *	new user session. getty is responsible for setting the line
 *	characteristics to a reasonable set of values and getting
 *	the name of the user to be logged in. login may also be
 *	called to create a new user session on a pty for a variety
 *	of reasons, such as X servers or network logins.
 *
 *	the flags which login supports are
 *	
 *	-p - preserve the environment
 *	-r - perform autologin protocol for rlogin
 *	-f - do not perform authentication, user is preauthenticated
 *	-h - the name of the remote host
 */
int main (int argc, char **argv)
{
	const char *tmptty;
	char tty[BUFSIZ];

#ifdef RLOGIN
	char term[128] = "";
#endif				/* RLOGIN */
#if defined(HAVE_STRFTIME) && !defined(USE_PAM)
	char ptime[80];
#endif
	unsigned int delay;
	unsigned int retries;
	bool subroot = false;
#ifndef USE_PAM
	bool is_console;
#endif
	int err;
	unsigned int timeout;
	const char *cp;
	const char *tmp;
	char fromhost[512];
	struct passwd *pwd = NULL;
	char **envp = environ;
	const char *failent_user;
#ifdef USE_UTMPX
	/*@null@*/struct utmpx *utent;
#else
	/*@null@*/struct utmp *utent;
#endif

#ifdef USE_PAM
	int retcode;
	pid_t child;
	char *pam_user = NULL;
#else
	struct spwd *spwd = NULL;
#endif
	/*
	 * Some quick initialization.
	 */

	sanitize_env ();

	(void) setlocale (LC_ALL, "");
	(void) bindtextdomain (PACKAGE, LOCALEDIR);
	(void) textdomain (PACKAGE);

	initenv ();

	amroot = (getuid () == 0);
	Prog = Basename (argv[0]);

	if (geteuid() != 0) {
		fprintf (stderr, _("%s: Cannot possibly work without effective root\n"), Prog);
		exit (1);
	}

	process_flags (argc, argv);

	if ((isatty (0) == 0) || (isatty (1) == 0) || (isatty (2) == 0)) {
		exit (1);	/* must be a terminal */
	}

	utent = get_current_utmp ();
	/*
	 * Be picky if run by normal users (possible if installed setuid
	 * root), but not if run by root. This way it still allows logins
	 * even if your getty is broken, or if something corrupts utmp,
	 * but users must "exec login" which will use the existing utmp
	 * entry (will not overwrite remote hostname).  --marekm
	 */
	if (!amroot && (NULL == utent)) {
		(void) puts (_("No utmp entry.  You must exec \"login\" from the lowest level \"sh\""));
		exit (1);
	}
	/* NOTE: utent might be NULL afterwards */

	tmptty = ttyname (0);
	if (NULL == tmptty) {
		tmptty = "UNKNOWN";
	}
	STRFCPY (tty, tmptty);

#ifndef USE_PAM
	is_console = console (tty);
#endif

	if (rflg || hflg) {
		/*
		 * Add remote hostname to the environment. I think
		 * (not sure) I saw it once on Irix.  --marekm
		 */
		addenv ("REMOTEHOST", hostname);
	}
	if (fflg) {
		preauth_flag = true;
	}
	if (hflg) {
		reason = PW_RLOGIN;
	}
#ifdef RLOGIN
	if (rflg) {
		assert (NULL == username);
		username = xmalloc (USER_NAME_MAX_LENGTH + 1);
		username[USER_NAME_MAX_LENGTH] = '\0';
		if (do_rlogin (hostname, username, USER_NAME_MAX_LENGTH, term, sizeof term)) {
			preauth_flag = true;
		} else {
			free (username);
			username = NULL;
		}
	}
#endif				/* RLOGIN */

	OPENLOG ("login");

	setup_tty ();

#ifndef USE_PAM
	(void) umask (getdef_num ("UMASK", GETDEF_DEFAULT_UMASK));

	{
		/* 
		 * Use the ULIMIT in the login.defs file, and if
		 * there isn't one, use the default value. The
		 * user may have one for themselves, but otherwise,
		 * just take what you get.
		 */
		long limit = getdef_long ("ULIMIT", -1L);

		if (limit != -1) {
			set_filesize_limit (limit);
		}
	}

#endif
	/*
	 * The entire environment will be preserved if the -p flag
	 * is used.
	 */
	if (pflg) {
		while (NULL != *envp) {	/* add inherited environment, */
			addenv (*envp, NULL); /* some variables change later */
			envp++;
		}
	}

#ifdef RLOGIN
	if (term[0] != '\0') {
		addenv ("TERM", term);
	} else
#endif				/* RLOGIN */
	{
		/* preserve TERM from getty */
		if (!pflg) {
			tmp = getenv ("TERM");
			if (NULL != tmp) {
				addenv ("TERM", tmp);
			}
		}
	}

	init_env ();

	if (optind < argc) {	/* now set command line variables */
		set_env (argc - optind, &argv[optind]);
	}

	if (rflg || hflg) {
		cp = hostname;
#if defined(HAVE_STRUCT_UTMP_UT_HOST) || defined(USE_UTMPX)
	} else if ((NULL != utent) && ('\0' != utent->ut_host[0])) {
		cp = utent->ut_host;
#endif				/* HAVE_STRUCT_UTMP_UT_HOST */
	} else {
		cp = "";
	}

	if ('\0' != *cp) {
		snprintf (fromhost, sizeof fromhost,
		          " on '%.100s' from '%.200s'", tty, cp);
	} else {
		snprintf (fromhost, sizeof fromhost,
		          " on '%.100s'", tty);
	}

      top:
	/* only allow ALARM sec. for login */
	timeout = getdef_unum ("LOGIN_TIMEOUT", ALARM);
	snprintf (tmsg, sizeof tmsg,
	          _("\nLogin timed out after %u seconds.\n"), timeout);
	(void) signal (SIGALRM, alarm_handler);
	if (timeout > 0) {
		(void) alarm (timeout);
	}

	environ = newenvp;	/* make new environment active */
	delay   = getdef_unum ("FAIL_DELAY", 1);
	retries = getdef_unum ("LOGIN_RETRIES", RETRIES);

#ifdef USE_PAM
	retcode = pam_start ("login", username, &conv, &pamh);
	if (retcode != PAM_SUCCESS) {
		fprintf (stderr,
		         _("login: PAM Failure, aborting: %s\n"),
		         pam_strerror (pamh, retcode));
		SYSLOG ((LOG_ERR, "Couldn't initialize PAM: %s",
		         pam_strerror (pamh, retcode)));
		exit (99);
	}

	/*
	 * hostname & tty are either set to NULL or their correct values,
	 * depending on how much we know. We also set PAM's fail delay to
	 * ours.
	 *
	 * PAM_RHOST and PAM_TTY are used for authentication, only use
	 * information coming from login or from the caller (e.g. no utmp)
	 */
	retcode = pam_set_item (pamh, PAM_RHOST, hostname);
	PAM_FAIL_CHECK;
	retcode = pam_set_item (pamh, PAM_TTY, tty);
	PAM_FAIL_CHECK;
#ifdef HAS_PAM_FAIL_DELAY
	retcode = pam_fail_delay (pamh, 1000000 * delay);
	PAM_FAIL_CHECK;
#endif
	/* if fflg, then the user has already been authenticated */
	if (!fflg) {
		unsigned int failcount = 0;
		char hostn[256];
		char loginprompt[256];	/* That's one hell of a prompt :) */

		/* Make the login prompt look like we want it */
		if (gethostname (hostn, sizeof (hostn)) == 0) {
			snprintf (loginprompt,
			          sizeof (loginprompt),
			          _("%s login: "), hostn);
		} else {
			strncpy (loginprompt, _("login: "),
			         sizeof (loginprompt));
		}

		retcode = pam_set_item (pamh, PAM_USER_PROMPT, loginprompt);
		PAM_FAIL_CHECK;

		/* if we didn't get a user on the command line,
		   set it to NULL */
		get_pam_user (&pam_user);
		if ((NULL != pam_user) && ('\0' == pam_user[0])) {
			retcode = pam_set_item (pamh, PAM_USER, NULL);
			PAM_FAIL_CHECK;
		}

		/*
		 * There may be better ways to deal with some of
		 * these conditions, but at least this way I don't
		 * think we'll be giving away information. Perhaps
		 * someday we can trust that all PAM modules will
		 * pay attention to failure count and get rid of
		 * MAX_LOGIN_TRIES?
		 */
		failcount = 0;
		while (true) {
			bool failed = false;

			failcount++;
#ifdef HAS_PAM_FAIL_DELAY
			if (delay > 0) {
				retcode = pam_fail_delay(pamh, 1000000*delay);
				PAM_FAIL_CHECK;
			}
#endif

			retcode = pam_authenticate (pamh, 0);

			get_pam_user (&pam_user);
			failent_user = get_failent_user (pam_user);

			if (retcode == PAM_MAXTRIES) {
				SYSLOG ((LOG_NOTICE,
				         "TOO MANY LOGIN TRIES (%u)%s FOR '%s'",
				         failcount, fromhost, failent_user));
				fprintf (stderr,
				         _("Maximum number of tries exceeded (%u)\n"),
				         failcount);
				PAM_END;
				exit(0);
			} else if (retcode == PAM_ABORT) {
				/* Serious problems, quit now */
				(void) fputs (_("login: abort requested by PAM\n"), stderr);
				SYSLOG ((LOG_ERR,"PAM_ABORT returned from pam_authenticate()"));
				PAM_END;
				exit(99);
			} else if (retcode != PAM_SUCCESS) {
				SYSLOG ((LOG_NOTICE,"FAILED LOGIN (%u)%s FOR '%s', %s",
				         failcount, fromhost, failent_user,
				         pam_strerror (pamh, retcode)));
				failed = true;
			}

			if (!failed) {
				break;
			}

#ifdef WITH_AUDIT
			audit_fd = audit_open ();
			audit_log_acct_message (audit_fd,
			                        AUDIT_USER_LOGIN,
			                        NULL,    /* Prog. name */
			                        "login",
			                        failent_user,
			                        AUDIT_NO_ID,
			                        hostname,
			                        NULL,    /* addr */
			                        tty,
			                        0);      /* result */
			close (audit_fd);
#endif				/* WITH_AUDIT */

			(void) puts ("");
			(void) puts (_("Login incorrect"));

			if (failcount >= retries) {
				SYSLOG ((LOG_NOTICE,
				         "TOO MANY LOGIN TRIES (%u)%s FOR '%s'",
				         failcount, fromhost, failent_user));
				fprintf (stderr,
				         _("Maximum number of tries exceeded (%u)\n"),
				         failcount);
				PAM_END;
				exit(0);
			}

			/*
			 * Let's give it another go around.
			 * Even if a username was given on the command
			 * line, prompt again for the username.
			 */
			retcode = pam_set_item (pamh, PAM_USER, NULL);
			PAM_FAIL_CHECK;
		}

		/* We don't get here unless they were authenticated above */
		(void) alarm (0);
	}

	/* Check the account validity */
	retcode = pam_acct_mgmt (pamh, 0);
	if (retcode == PAM_NEW_AUTHTOK_REQD) {
		retcode = pam_chauthtok (pamh, PAM_CHANGE_EXPIRED_AUTHTOK);
	}
	PAM_FAIL_CHECK;

	/* Open the PAM session */
	get_pam_user (&pam_user);
	retcode = pam_open_session (pamh, hushed (pam_user) ? PAM_SILENT : 0);
	PAM_FAIL_CHECK;

	/* Grab the user information out of the password file for future usage
	 * First get the username that we are actually using, though.
	 *
	 * From now on, we will discard changes of the user (PAM_USER) by
	 * PAM APIs.
	 */
	get_pam_user (&pam_user);
	if (NULL != username) {
		free (username);
	}
	username = xstrdup (pam_user);
	failent_user = get_failent_user (username);

	pwd = xgetpwnam (username);
	if (NULL == pwd) {
		SYSLOG ((LOG_ERR, "cannot find user %s", failent_user));
		fprintf (stderr,
		         _("Cannot find user (%s)\n"),
		         username);
		exit (1);
	}

	/* This set up the process credential (group) and initialize the
	 * supplementary group access list.
	 * This has to be done before pam_setcred
	 */
	if (setup_groups (pwd) != 0) {
		exit (1);
	}

	retcode = pam_setcred (pamh, PAM_ESTABLISH_CRED);
	PAM_FAIL_CHECK;
	/* NOTE: If pam_setcred changes PAM_USER, this will not be taken
	 * into account.
	 */

#else				/* ! USE_PAM */
	while (true) {	/* repeatedly get login/password pairs */
		bool failed;
		/* user_passwd is always a pointer to this constant string
		 * or a passwd or shadow password that will be memzero by
		 * pw_free / spw_free.
		 * Do not free() user_passwd. */
		const char *user_passwd = "!";

		/* Do some cleanup to avoid keeping entries we do not need
		 * anymore. */
		if (NULL != pwd) {
			pw_free (pwd);
			pwd = NULL;
		}
		if (NULL != spwd) {
			spw_free (spwd);
			spwd = NULL;
		}

		failed = false;	/* haven't failed authentication yet */
		if (NULL == username) {	/* need to get a login id */
			if (subroot) {
				closelog ();
				exit (1);
			}
			preauth_flag = false;
			username = xmalloc (USER_NAME_MAX_LENGTH + 1);
			username[USER_NAME_MAX_LENGTH] = '\0';
			login_prompt (_("\n%s login: "), username, USER_NAME_MAX_LENGTH);

			if ('\0' == username[0]) {
				/* Prompt for a new login */
				free (username);
				username = NULL;
				continue;
			}
		}
		/* Get the username to be used to log failures */
		failent_user = get_failent_user (username);

		pwd = xgetpwnam (username);
		if (NULL == pwd) {
			preauth_flag = false;
			failed = true;
		} else {
			user_passwd = pwd->pw_passwd;
			/*
			 * If the encrypted password begins with a "!",
			 * the account is locked and the user cannot
			 * login, even if they have been
			 * "pre-authenticated."
			 */
			if (   ('!' == user_passwd[0])
			    || ('*' == user_passwd[0])) {
				failed = true;
			}
		}

		if (strcmp (user_passwd, SHADOW_PASSWD_STRING) == 0) {
			spwd = xgetspnam (username);
			if (NULL != spwd) {
				user_passwd = spwd->sp_pwdp;
			} else {
				/* The user exists in passwd, but not in
				 * shadow. SHADOW_PASSWD_STRING indicates
				 * that the password shall be in shadow.
				 */
				SYSLOG ((LOG_WARN,
				         "no shadow password for '%s'%s",
				         username, fromhost));
			}
		}

		/*
		 * The -r and -f flags provide a name which has already
		 * been authenticated by some server.
		 */
		if (preauth_flag) {
			goto auth_ok;
		}

		if (pw_auth (user_passwd, username, reason, (char *) 0) == 0) {
			goto auth_ok;
		}

		SYSLOG ((LOG_WARN, "invalid password for '%s' %s",
		         failent_user, fromhost));
		failed = true;

	      auth_ok:
		/*
		 * This is the point where all authenticated users wind up.
		 * If you reach this far, your password has been
		 * authenticated and so on.
		 */
		if (   !failed
		    && (NULL != pwd)
		    && (0 == pwd->pw_uid)
		    && !is_console) {
			SYSLOG ((LOG_CRIT, "ILLEGAL ROOT LOGIN %s", fromhost));
			failed = true;
		}
		if (   !failed
		    && !login_access (username, ('\0' != *hostname) ? hostname : tty)) {
			SYSLOG ((LOG_WARN, "LOGIN '%s' REFUSED %s",
			         username, fromhost));
			failed = true;
		}
		if (   (NULL != pwd)
		    && getdef_bool ("FAILLOG_ENAB")
		    && !failcheck (pwd->pw_uid, &faillog, failed)) {
			SYSLOG ((LOG_CRIT,
			         "exceeded failure limit for '%s' %s",
			         username, fromhost));
			failed = true;
		}
		if (!failed) {
			break;
		}

		/* don't log non-existent users */
		if ((NULL != pwd) && getdef_bool ("FAILLOG_ENAB")) {
			failure (pwd->pw_uid, tty, &faillog);
		}
		if (getdef_str ("FTMP_FILE") != NULL) {
#ifdef USE_UTMPX
			struct utmpx *failent =
				prepare_utmpx (failent_user,
				               tty,
			/* FIXME: or fromhost? */hostname,
				               utent);
#else				/* !USE_UTMPX */
			struct utmp *failent =
				prepare_utmp (failent_user,
				              tty,
				              hostname,
				              utent);
#endif				/* !USE_UTMPX */
			failtmp (failent_user, failent);
			free (failent);
		}

		retries--;
		if (retries <= 0) {
			SYSLOG ((LOG_CRIT, "REPEATED login failures%s",
			         fromhost));
		}

		/*
		 * If this was a passwordless account and we get here, login
		 * was denied (securetty, faillog, etc.). There was no
		 * password prompt, so do it now (will always fail - the bad
		 * guys won't see that the passwordless account exists at
		 * all).  --marekm
		 */
		if (user_passwd[0] == '\0') {
			pw_auth ("!", username, reason, (char *) 0);
		}

		/*
		 * Authentication of this user failed.
		 * The username must be confirmed in the next try.
		 */
		free (username);
		username = NULL;

		/*
		 * Wait a while (a la SVR4 /usr/bin/login) before attempting
		 * to login the user again. If the earlier alarm occurs
		 * before the sleep() below completes, login will exit.
		 */
		if (delay > 0) {
			(void) sleep (delay);
		}

		(void) puts (_("Login incorrect"));

		/* allow only one attempt with -r or -f */
		if (rflg || fflg || (retries <= 0)) {
			closelog ();
			exit (1);
		}
	}			/* while (true) */
#endif				/* ! USE_PAM */
	assert (NULL != username);
	assert (NULL != pwd);

	(void) alarm (0);		/* turn off alarm clock */

#ifndef USE_PAM			/* PAM does this */
	/*
	 * porttime checks moved here, after the user has been
	 * authenticated. now prints a message, as suggested
	 * by Ivan Nejgebauer <ian@unsux.ns.ac.yu>.  --marekm
	 */
	if (   getdef_bool ("PORTTIME_CHECKS_ENAB")
	    && !isttytime (username, tty, time ((time_t *) 0))) {
		SYSLOG ((LOG_WARN, "invalid login time for '%s'%s",
		         username, fromhost));
		closelog ();
		bad_time_notify ();
		exit (1);
	}

	check_nologin (pwd->pw_uid == 0);
#endif

	if (getenv ("IFS")) {	/* don't export user IFS ... */
		addenv ("IFS= \t\n", NULL);	/* ... instead, set a safe IFS */
	}

	if (pwd->pw_shell[0] == '*') {	/* subsystem root */
		pwd->pw_shell++;	/* skip the '*' */
		subsystem (pwd);	/* figure out what to execute */
		subroot = true;	/* say I was here again */
		endpwent ();	/* close all of the file which were */
		endgrent ();	/* open in the original rooted file */
		endspent ();	/* system. they will be re-opened */
#ifdef	SHADOWGRP
		endsgent ();	/* in the new rooted file system */
#endif
		goto top;	/* go do all this all over again */
	}

#ifdef WITH_AUDIT
	audit_fd = audit_open ();
	audit_log_acct_message (audit_fd,
	                        AUDIT_USER_LOGIN,
	                        NULL,    /* Prog. name */
	                        "login",
	                        username,
	                        AUDIT_NO_ID,
	                        hostname,
	                        NULL,    /* addr */
	                        tty,
	                        1);      /* result */
	close (audit_fd);
#endif				/* WITH_AUDIT */

#ifndef USE_PAM			/* pam_lastlog handles this */
	if (   getdef_bool ("LASTLOG_ENAB")
	    && pwd->pw_uid <= (uid_t) getdef_ulong ("LASTLOG_UID_MAX", 0xFFFFFFFFUL)) {
		/* give last login and log this one */
		dolastlog (&ll, pwd, tty, hostname);
	}
#endif

#ifndef USE_PAM			/* PAM handles this as well */
	/*
	 * Have to do this while we still have root privileges, otherwise we
	 * don't have access to /etc/shadow.
	 */
	if (NULL != spwd) {		/* check for age of password */
		if (expire (pwd, spwd)) {
			/* The user updated her password, get the new
			 * entries.
			 * Use the x variants because we need to keep the
			 * entry for a long time, and there might be other
			 * getxxyyy in between.
			 */
			pw_free (pwd);
			pwd = xgetpwnam (username);
			if (NULL == pwd) {
				SYSLOG ((LOG_ERR,
				         "cannot find user %s after update of expired password",
				         username));
				exit (1);
			}
			spw_free (spwd);
			spwd = xgetspnam (username);
		}
	}
	setup_limits (pwd);	/* nice, ulimit etc. */
#endif				/* ! USE_PAM */
	chown_tty (pwd);

#ifdef USE_PAM
	/*
	 * We must fork before setuid() because we need to call
	 * pam_close_session() as root.
	 */
	(void) signal (SIGINT, SIG_IGN);
	child = fork ();
	if (child < 0) {
		/* error in fork() */
		fprintf (stderr, _("%s: failure forking: %s"),
		         Prog, strerror (errno));
		PAM_END;
		exit (0);
	} else if (child != 0) {
		/*
		 * parent - wait for child to finish, then cleanup
		 * session
		 */
		wait (NULL);
		PAM_END;
		exit (0);
	}
	/* child */
#endif

	/* If we were init, we need to start a new session */
	if (getppid() == 1) {
		setsid();
		if (ioctl(0, TIOCSCTTY, 1) != 0) {
			fprintf (stderr, _("TIOCSCTTY failed on %s"), tty);
		}
	}

	/*
	 * The utmp entry needs to be updated to indicate the new status
	 * of the session, the new PID and SID.
	 */
	update_utmp (username, tty, hostname, utent);

	/* The pwd and spwd entries for the user have been copied.
	 *
	 * Close all the files so that unauthorized access won't occur.
	 */
	endpwent ();		/* stop access to password file */
	endgrent ();		/* stop access to group file */
	endspent ();		/* stop access to shadow passwd file */
#ifdef	SHADOWGRP
	endsgent ();		/* stop access to shadow group file */
#endif

	/* Drop root privileges */
#ifndef USE_PAM
	if (setup_uid_gid (pwd, is_console))
#else
	/* The group privileges were already dropped.
	 * See setup_groups() above.
	 */
	if (change_uid (pwd))
#endif
	{
		exit (1);
	}

	setup_env (pwd);	/* set env vars, cd to the home dir */

#ifdef USE_PAM
	{
		const char *const *env;

		env = (const char *const *) pam_getenvlist (pamh);
		while ((NULL != env) && (NULL != *env)) {
			addenv (*env, NULL);
			env++;
		}
	}
#endif

	(void) setlocale (LC_ALL, "");
	(void) bindtextdomain (PACKAGE, LOCALEDIR);
	(void) textdomain (PACKAGE);

	if (!hushed (username)) {
		addenv ("HUSHLOGIN=FALSE", NULL);
		/*
		 * pam_unix, pam_mail and pam_lastlog should take care of
		 * this
		 */
#ifndef USE_PAM
		motd ();	/* print the message of the day */
		if (   getdef_bool ("FAILLOG_ENAB")
		    && (0 != faillog.fail_cnt)) {
			failprint (&faillog);
			/* Reset the lockout times if logged in */
			if (   (0 != faillog.fail_max)
			    && (faillog.fail_cnt >= faillog.fail_max)) {
				(void) puts (_("Warning: login re-enabled after temporary lockout."));
				SYSLOG ((LOG_WARN,
				         "login '%s' re-enabled after temporary lockout (%d failures)",
				         username, (int) faillog.fail_cnt));
			}
		}
		if (   getdef_bool ("LASTLOG_ENAB")
		    && pwd->pw_uid <= (uid_t) getdef_ulong ("LASTLOG_UID_MAX", 0xFFFFFFFFUL)
		    && (ll.ll_time != 0)) {
			time_t ll_time = ll.ll_time;

#ifdef HAVE_STRFTIME
			(void) strftime (ptime, sizeof (ptime),
			                 "%a %b %e %H:%M:%S %z %Y",
			                 localtime (&ll_time));
			printf (_("Last login: %s on %s"),
			        ptime, ll.ll_line);
#else
			printf (_("Last login: %.19s on %s"),
			        ctime (&ll_time), ll.ll_line);
#endif
#ifdef HAVE_LL_HOST		/* __linux__ || SUN4 */
			if ('\0' != ll.ll_host[0]) {
				printf (_(" from %.*s"),
				        (int) sizeof ll.ll_host, ll.ll_host);
			}
#endif
			printf (".\n");
		}
		agecheck (spwd);

		mailcheck ();	/* report on the status of mail */
#endif				/* !USE_PAM */
	} else {
		addenv ("HUSHLOGIN=TRUE", NULL);
	}

	ttytype (tty);

	(void) signal (SIGQUIT, SIG_DFL);	/* default quit signal */
	(void) signal (SIGTERM, SIG_DFL);	/* default terminate signal */
	(void) signal (SIGALRM, SIG_DFL);	/* default alarm signal */
	(void) signal (SIGHUP, SIG_DFL);	/* added this.  --marekm */
	(void) signal (SIGINT, SIG_DFL);	/* default interrupt signal */

	if (0 == pwd->pw_uid) {
		SYSLOG ((LOG_NOTICE, "ROOT LOGIN %s", fromhost));
	} else if (getdef_bool ("LOG_OK_LOGINS")) {
		SYSLOG ((LOG_INFO, "'%s' logged in %s", username, fromhost));
	}
	closelog ();
	tmp = getdef_str ("FAKE_SHELL");
	if (NULL != tmp) {
		err = shell (tmp, pwd->pw_shell, newenvp); /* fake shell */
	} else {
		/* exec the shell finally */
		err = shell (pwd->pw_shell, (char *) 0, newenvp);
	}

	return ((err == ENOENT) ? E_CMD_NOTFOUND : E_CMD_NOEXEC);
}