summaryrefslogtreecommitdiff
path: root/modules/pam_env/pam_env.c
blob: d2b4cb10f2a12047a4333ef508e94ae9a5a6f48d (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
/*
 * pam_env module
 *
 * Written by Dave Kinchlea <kinch@kinch.ark.com> 1997/01/31
 * Inspired by Andrew Morgan <morgan@kernel.org>, who also supplied the
 * template for this file (via pam_mail)
 */

#define DEFAULT_ETC_ENVFILE     "/etc/environment"
#ifdef VENDORDIR
#define VENDOR_DEFAULT_ETC_ENVFILE (VENDORDIR "/environment")
#endif
#define DEFAULT_READ_ENVFILE    1

#define DEFAULT_USER_ENVFILE    ".pam_environment"
#define DEFAULT_USER_READ_ENVFILE 0

#include "config.h"

#include <ctype.h>
#include <errno.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#ifdef USE_ECONF
#include <libeconf.h>
#endif

#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <security/_pam_macros.h>
#include <security/pam_ext.h>
#include "pam_inline.h"

/* This little structure makes it easier to keep variables together */

typedef struct var {
  char *name;
  char *value;
  char *defval;
  char *override;
} VAR;

#define DEFAULT_CONF_FILE	(SCONFIGDIR "/pam_env.conf")
#ifdef VENDOR_SCONFIGDIR
#define VENDOR_DEFAULT_CONF_FILE (VENDOR_SCONFIGDIR "/pam_env.conf")
#endif

#define BUF_SIZE 8192
#define MAX_ENV  8192

#define GOOD_LINE    0
#define BAD_LINE     100       /* This must be > the largest PAM_* error code */

#define DEFINE_VAR   101
#define UNDEFINE_VAR 102
#define ILLEGAL_VAR  103

/* This is a special value used to designate an empty string */
static char quote='\0';

static void free_string_array(char **array)
{
    if (array == NULL)
      return;
    for (char **entry = array; *entry != NULL; ++entry) {
      pam_overwrite_string(*entry);
      free(*entry);
    }
    free(array);
}

/* argument parsing */

#define PAM_DEBUG_ARG       0x01

static int
_pam_parse (const pam_handle_t *pamh, int argc, const char **argv,
	    const char **conffile, const char **envfile, int *readenv,
	    const char **user_envfile, int *user_readenv)
{
    int ctrl=0;

    *user_envfile = DEFAULT_USER_ENVFILE;
    *envfile = NULL;
    *readenv = DEFAULT_READ_ENVFILE;
    *user_readenv = DEFAULT_USER_READ_ENVFILE;
    *conffile = NULL;

    /* step through arguments */
    for (; argc-- > 0; ++argv) {
	const char *str;

	/* generic options */

	if (!strcmp(*argv,"debug"))
	    ctrl |= PAM_DEBUG_ARG;
	else if ((str = pam_str_skip_prefix(*argv, "conffile=")) != NULL) {
	  if (str[0] == '\0') {
	    pam_syslog(pamh, LOG_ERR,
		       "conffile= specification missing argument - ignored");
	  } else {
	    *conffile = str;
	    D(("new Configuration File: %s", *conffile));
	  }
	} else if ((str = pam_str_skip_prefix(*argv, "envfile=")) != NULL) {
	  if (str[0] == '\0') {
	    pam_syslog (pamh, LOG_ERR,
			"envfile= specification missing argument - ignored");
	  } else {
	    *envfile = str;
	    D(("new Env File: %s", *envfile));
	  }
	} else if ((str = pam_str_skip_prefix(*argv, "user_envfile=")) != NULL) {
	  if (str[0] == '\0') {
	    pam_syslog (pamh, LOG_ERR,
			"user_envfile= specification missing argument - ignored");
	  } else {
	    *user_envfile = str;
	    D(("new User Env File: %s", *user_envfile));
	  }
	} else if ((str = pam_str_skip_prefix(*argv, "readenv=")) != NULL) {
	  *readenv = atoi(str);
	} else if ((str = pam_str_skip_prefix(*argv, "user_readenv=")) != NULL) {
	  *user_readenv = atoi(str);
	} else
	  pam_syslog(pamh, LOG_ERR, "unknown option: %s", *argv);
    }

    if (*user_readenv)
	pam_syslog(pamh, LOG_DEBUG, "deprecated reading of user environment enabled");

    return ctrl;
}

#ifdef USE_ECONF

#define ENVIRONMENT "environment"
#define PAM_ENV "pam_env"

static int
isDirectory(const char *path) {
   struct stat statbuf;
   if (stat(path, &statbuf) != 0)
       return 0;
   return S_ISDIR(statbuf.st_mode);
}

static int
econf_read_file(const pam_handle_t *pamh, const char *filename, const char *delim,
			   const char *name, const char *suffix, const char *subpath,
			   char ***lines)
{
    econf_file *key_file = NULL;
    econf_err error;
    size_t key_number = 0;
    char **keys = NULL;
    const char *base_dir = "";

    if (filename != NULL) {
      if (isDirectory(filename)) {
	/* Set base directory which can be different from root */
	D(("filename argument is a directory: %s", filename));
	base_dir = filename;
      } else {
	/* Read only one file */
	error = econf_readFile (&key_file, filename, delim, "#");
	D(("File name is: %s", filename));
	if (error != ECONF_SUCCESS) {
	  pam_syslog(pamh, LOG_ERR, "Unable to open env file: %s: %s", filename,
		     econf_errString(error));
          if (error == ECONF_NOFILE)
            return PAM_IGNORE;
          else
            return PAM_ABORT;
	}
      }
    }
    if (filename == NULL || base_dir[0] != '\0') {
      /* Read and merge all setting in e.g. /usr/etc and /etc */
      char *vendor_dir = NULL, *sysconf_dir;
      if (subpath != NULL && subpath[0] != '\0') {
#ifdef VENDORDIR
	if (asprintf(&vendor_dir, "%s%s/%s/", base_dir, VENDORDIR, subpath) < 0) {
	  pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
	  return PAM_BUF_ERR;
	}
#endif
	if (asprintf(&sysconf_dir, "%s%s/%s/", base_dir, SYSCONFDIR, subpath) < 0) {
	  pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
	  free(vendor_dir);
	  return PAM_BUF_ERR;
	}
      } else {
#ifdef VENDORDIR
	if (asprintf(&vendor_dir, "%s%s/", base_dir, VENDORDIR) < 0) {
	  pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
	  return PAM_BUF_ERR;
	}
#endif
	if (asprintf(&sysconf_dir, "%s%s/", base_dir, SYSCONFDIR) < 0) {
	  pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
	  free(vendor_dir);
	  return PAM_BUF_ERR;
	}
      }

      D(("Read configuration from directory %s and %s", vendor_dir, sysconf_dir));
      error = econf_readDirs (&key_file, vendor_dir, sysconf_dir, name, suffix,
			      delim, "#");
      free(vendor_dir);
      free(sysconf_dir);
      if (error != ECONF_SUCCESS) {
        if (error == ECONF_NOFILE) {
	  pam_syslog(pamh, LOG_ERR, "Configuration file not found: %s%s", name, suffix);
          return PAM_IGNORE;
        } else {
          char *error_filename = NULL;
          uint64_t error_line = 0;

          econf_errLocation(&error_filename, &error_line);
          pam_syslog(pamh, LOG_ERR, "Unable to read configuration file %s line %ld: %s",
                     error_filename,
                     error_line,
                     econf_errString(error));
          free(error_filename);
          return PAM_ABORT;
	}
      }
    }

    error = econf_getKeys(key_file, NULL, &key_number, &keys);
    if (error != ECONF_SUCCESS && error != ECONF_NOKEY) {
      pam_syslog(pamh, LOG_ERR, "Unable to read keys: %s",
		 econf_errString(error));
      econf_freeFile(key_file);
      return PAM_ABORT;
    }

    *lines = malloc((key_number +1)* sizeof(char**));
    if (*lines == NULL) {
      pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
      econf_free(keys);
      econf_freeFile(key_file);
      return PAM_BUF_ERR;
    }

    (*lines)[key_number] = 0;

    for (size_t i = 0; i < key_number; i++) {
      char *val;

      error = econf_getStringValue (key_file, NULL, keys[i], &val);
      if (error != ECONF_SUCCESS) {
	pam_syslog(pamh, LOG_ERR, "Unable to get string from key %s: %s",
		   keys[i],
		   econf_errString(error));
      } else {
        if (asprintf(&(*lines)[i],"%s%c%s", keys[i], delim[0], val) < 0) {
	  pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
          econf_free(keys);
          econf_freeFile(key_file);
	  (*lines)[i] = NULL;
	  free_string_array(*lines);
	  free (val);
	  return PAM_BUF_ERR;
	}
	free (val);
      }
    }

    econf_free(keys);
    econf_free(key_file);
    return PAM_SUCCESS;
}

#else

/*
 * This is where we read a line of the PAM config file. The line may be
 * preceded by lines of comments and also extended with "\\\n"
 */
static int
_assemble_line(FILE *f, char *buffer, int buf_len)
{
    char *p = buffer;
    char *s, *os;
    int used = 0;
    int whitespace;

    /* loop broken with a 'break' when a non-'\\n' ended line is read */

    D(("called."));
    for (;;) {
	if (used >= buf_len) {
	    /* Overflow */
	    D(("_assemble_line: overflow"));
	    return -1;
	}
	if (fgets(p, buf_len - used, f) == NULL) {
	    if (used) {
		/* Incomplete read */
		return -1;
	    } else {
		/* EOF */
		return 0;
	    }
	}
	if (p[0] == '\0') {
	    D(("_assemble_line: corrupted or binary file"));
	    return -1;
	}
	if (p[strlen(p)-1] != '\n' && !feof(f)) {
	    D(("_assemble_line: line too long"));
	    return -1;
	}

	/* skip leading spaces --- line may be blank */

	whitespace = strspn(p, " \n\t");
	s = p + whitespace;
	if (*s && (*s != '#')) {
	    used += whitespace;
	    os = s;

	    /*
	     * we are only interested in characters before the first '#'
	     * character
	     */

	    while (*s && *s != '#')
		 ++s;
	    if (*s == '#') {
		 *s = '\0';
		 used += strlen(os);
		 break;                /* the line has been read */
	    }

	    s = os;

	    /*
	     * Check for backslash by scanning back from the end of
	     * the entered line, the '\n' has been included since
	     * normally a line is terminated with this
	     * character. fgets() should only return one though!
	     */

	    s += strlen(s);
	    while (s > os && ((*--s == ' ') || (*s == '\t')
			      || (*s == '\n')));

	    /* check if it ends with a backslash */
	    if (*s == '\\') {
		*s = '\0';              /* truncate the line here */
		used += strlen(os);
		p = s;                  /* there is more ... */
	    } else {
		/* End of the line! */
		used += strlen(os);
		break;                  /* this is the complete line */
	    }

	} else {
	    /* Nothing in this line */
	    /* Don't move p         */
	}
    }

    return used;
}

static int read_file(const pam_handle_t *pamh, const char*filename, char ***lines)
{
    FILE *conf;
    char buffer[BUF_SIZE];

    D(("Parsed file name is: %s", filename));

    if ((conf = fopen(filename,"r")) == NULL) {
      pam_syslog(pamh, LOG_ERR, "Unable to open env file: %s", filename);
      return PAM_IGNORE;
    }

    size_t i = 0;
    *lines = malloc((i + 1)* sizeof(char**));
    if (*lines == NULL) {
      pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
      (void) fclose(conf);
      return PAM_BUF_ERR;
    }
    (*lines)[i] = 0;
    while (_assemble_line(conf, buffer, BUF_SIZE) > 0) {
      char **tmp = NULL;
      D(("Read line: %s", buffer));
      tmp = realloc(*lines, (++i + 1) * sizeof(char**));
      if (tmp == NULL) {
	pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
	(void) fclose(conf);
	free_string_array(*lines);
	pam_overwrite_array(buffer);
	return PAM_BUF_ERR;
      }
      *lines = tmp;
      (*lines)[i-1] = strdup(buffer);
      if ((*lines)[i-1] == NULL) {
        pam_syslog(pamh, LOG_ERR, "Cannot allocate memory.");
        (void) fclose(conf);
        free_string_array(*lines);
        pam_overwrite_array(buffer);
        return PAM_BUF_ERR;
      }
      (*lines)[i] = 0;
    }

    (void) fclose(conf);
    pam_overwrite_array(buffer);
    return PAM_SUCCESS;
}
#endif

static int
_parse_line(const pam_handle_t *pamh, const char *buffer, VAR *var)
{
  /*
   * parse buffer into var, legal syntax is
   * VARIABLE [DEFAULT=[[string]] [OVERRIDE=[value]]
   *
   * Any other options defined make this a bad line,
   * error logged and no var set
   */

  int length, quoteflg=0;
  const char *ptr, *tmpptr;
  char **valptr;

  D(("Called buffer = <%s>", buffer));

  length = strcspn(buffer," \t\n");

  if ((var->name = malloc(length + 1)) == NULL) {
    pam_syslog(pamh, LOG_CRIT, "Couldn't malloc %d bytes", length+1);
    return PAM_BUF_ERR;
  }

  /*
   * The first thing on the line HAS to be the variable name,
   * it may be the only thing though.
   */
  strncpy(var->name, buffer, length);
  var->name[length] = '\0';
  D(("var->name = <%s>, length = %d", var->name, length));

  /*
   * Now we check for arguments, we only support two kinds and ('cause I am lazy)
   * each one can actually be listed any number of times
   */

  ptr = buffer+length;
  while ((length = strspn(ptr, " \t")) > 0) {
    ptr += length;                              /* remove leading whitespace */
    D((ptr));
    if ((tmpptr = pam_str_skip_prefix(ptr, "DEFAULT=")) != NULL) {
      ptr = tmpptr;
      D(("Default arg found: <%s>", ptr));
      valptr=&(var->defval);
    } else if ((tmpptr = pam_str_skip_prefix(ptr, "OVERRIDE=")) != NULL) {
      ptr = tmpptr;
      D(("Override arg found: <%s>", ptr));
      valptr=&(var->override);
    } else {
      D(("Unrecognized options: <%s> - ignoring line", ptr));
      pam_syslog(pamh, LOG_ERR, "Unrecognized Option: %s - ignoring line", ptr);
      return BAD_LINE;
    }

    if ('"' != *ptr) {       /* Escaped quotes not supported */
      length = strcspn(ptr, " \t\n");
      tmpptr = ptr+length;
    } else {
      tmpptr = strchr(++ptr, '"');
      if (!tmpptr) {
	D(("Unterminated quoted string: %s", ptr-1));
	pam_syslog(pamh, LOG_ERR, "Unterminated quoted string: %s", ptr-1);
	return BAD_LINE;
      }
      length = tmpptr - ptr;
      if (*++tmpptr && ' ' != *tmpptr && '\t' != *tmpptr && '\n' != *tmpptr) {
	D(("Quotes must cover the entire string: <%s>", ptr));
	pam_syslog(pamh, LOG_ERR, "Quotes must cover the entire string: <%s>", ptr);
	return BAD_LINE;
      }
      quoteflg++;
    }
    if (length) {
      if ((*valptr = malloc(length + 1)) == NULL) {
	D(("Couldn't malloc %d bytes", length+1));
	pam_syslog(pamh, LOG_CRIT, "Couldn't malloc %d bytes", length+1);
	return PAM_BUF_ERR;
      }
      (void)strncpy(*valptr,ptr,length);
      (*valptr)[length]='\0';
    } else if (quoteflg) {
      quoteflg--;
      *valptr = &quote;      /* a quick hack to handle the empty string */
    }
    ptr = tmpptr;         /* Start the search where we stopped */
  } /* while */

  /*
   * The line is parsed, all is well.
   */

  D(("Exit."));
  ptr = NULL; tmpptr = NULL; valptr = NULL;
  return GOOD_LINE;
}

static const char *
_pam_get_item_byname(pam_handle_t *pamh, const char *name)
{
  /*
   * This function just allows me to use names as given in the config
   * file and translate them into the appropriate PAM_ITEM macro
   */

  int item;
  const void *itemval;

  D(("Called."));
  if (strcmp(name, "PAM_USER") == 0 || strcmp(name, "HOME") == 0 || strcmp(name, "SHELL") == 0) {
    item = PAM_USER;
  } else if (strcmp(name, "PAM_USER_PROMPT") == 0) {
    item = PAM_USER_PROMPT;
  } else if (strcmp(name, "PAM_TTY") == 0) {
    item = PAM_TTY;
  } else if (strcmp(name, "PAM_RUSER") == 0) {
    item = PAM_RUSER;
  } else if (strcmp(name, "PAM_RHOST") == 0) {
    item = PAM_RHOST;
  } else {
    D(("Unknown PAM_ITEM: <%s>", name));
    pam_syslog (pamh, LOG_ERR, "Unknown PAM_ITEM: <%s>", name);
    return NULL;
  }

  if (pam_get_item(pamh, item, &itemval) != PAM_SUCCESS) {
    D(("pam_get_item failed"));
    return NULL;     /* let pam_get_item() log the error */
  }

  if (itemval && (strcmp(name, "HOME") == 0 || strcmp(name, "SHELL") == 0)) {
    struct passwd *user_entry;
    user_entry = pam_modutil_getpwnam (pamh, itemval);
    if (!user_entry) {
      pam_syslog(pamh, LOG_ERR, "No such user!?");
      return NULL;
    }
    return (strcmp(name, "SHELL") == 0) ?
      user_entry->pw_shell :
      user_entry->pw_dir;
  }

  D(("Exit."));
  return itemval;
}

static int
_expand_arg(pam_handle_t *pamh, char **value)
{
  const char *orig=*value, *tmpptr=NULL;
  char *ptr;       /*
		    * Sure would be nice to use tmpptr but it needs to be
		    * a constant so that the compiler will shut up when I
		    * call pam_getenv and _pam_get_item_byname -- sigh
		    */

  /* No unexpanded variable can be bigger than BUF_SIZE */
  char type, tmpval[BUF_SIZE];

  /* I know this shouldn't be hard-coded but it's so much easier this way */
  char tmp[MAX_ENV] = {};
  size_t idx = 0;

  /*
   * (possibly non-existent) environment variables can be used as values
   * by prepending a "$" and wrapping in {} (ie: ${HOST}), can escape with "\"
   * (possibly non-existent) PAM items can be used as values
   * by prepending a "@" and wrapping in {} (ie: @{PAM_RHOST}, can escape
   *
   */
  D(("Expanding <%s>",orig));
  while (*orig) {     /* while there is some input to deal with */
    if ('\\' == *orig) {
      ++orig;
      if ('$' != *orig && '@' != *orig) {
	D(("Unrecognized escaped character: <%c> - ignoring", *orig));
	pam_syslog(pamh, LOG_ERR,
		   "Unrecognized escaped character: <%c> - ignoring",
		   *orig);
      } else if (idx + 1 < MAX_ENV) {
	tmp[idx++] = *orig++;        /* Note the increment */
      } else {
	/* is it really a good idea to try to log this? */
	D(("Variable buffer overflow: <%s> + <%s>", tmp, tmpptr));
	pam_syslog (pamh, LOG_ERR, "Variable buffer overflow: <%s> + <%s>",
		 tmp, tmpptr);
	goto buf_err;
      }
      continue;
    }
    if ('$' == *orig || '@' == *orig) {
      if ('{' != *(orig+1)) {
	D(("Expandable variables must be wrapped in {}"
	   " <%s> - ignoring", orig));
	pam_syslog(pamh, LOG_ERR, "Expandable variables must be wrapped in {}"
		 " <%s> - ignoring", orig);
	if (idx + 1 < MAX_ENV) {
	  tmp[idx++] = *orig++;        /* Note the increment */
	}
	continue;
      } else {
	D(("Expandable argument: <%s>", orig));
	type = *orig;
	orig+=2;     /* skip the ${ or @{ characters */
	ptr = strchr(orig, '}');
	if (ptr) {
	  *ptr++ = '\0';
	} else {
	  D(("Unterminated expandable variable: <%s>", orig-2));
	  pam_syslog(pamh, LOG_ERR,
		     "Unterminated expandable variable: <%s>", orig-2);
	  goto abort_err;
	}
	strncpy(tmpval, orig, sizeof(tmpval));
	tmpval[sizeof(tmpval)-1] = '\0';
	orig=ptr;
	/*
	 * so, we know we need to expand tmpval, it is either
	 * an environment variable or a PAM_ITEM. type will tell us which
	 */
	switch (type) {

	case '$':
	  D(("Expanding env var: <%s>",tmpval));
	  tmpptr = pam_getenv(pamh, tmpval);
	  D(("Expanded to <%s>", tmpptr));
	  break;

	case '@':
	  D(("Expanding pam item: <%s>",tmpval));
	  tmpptr = _pam_get_item_byname(pamh, tmpval);
	  D(("Expanded to <%s>", tmpptr));
	  break;

	default:
	  D(("Impossible error, type == <%c>", type));
	  pam_syslog(pamh, LOG_CRIT, "Impossible error, type == <%c>", type);
	  goto abort_err;
	}         /* switch */

	if (tmpptr) {
	  size_t len = strlen(tmpptr);
	  if (idx + len < MAX_ENV) {
	    strcpy(tmp + idx, tmpptr);
	    idx += len;
	  } else {
	    /* is it really a good idea to try to log this? */
	    D(("Variable buffer overflow: <%s> + <%s>", tmp, tmpptr));
	    pam_syslog (pamh, LOG_ERR,
			"Variable buffer overflow: <%s> + <%s>", tmp, tmpptr);
	    goto buf_err;
	  }
	}
      }           /* if ('{' != *orig++) */
    } else {      /* if ( '$' == *orig || '@' == *orig) */
      if (idx + 1 < MAX_ENV) {
	tmp[idx++] = *orig++;        /* Note the increment */
      } else {
	/* is it really a good idea to try to log this? */
	D(("Variable buffer overflow: <%s> + <%s>", tmp, tmpptr));
	pam_syslog(pamh, LOG_ERR,
		   "Variable buffer overflow: <%s> + <%s>", tmp, tmpptr);
	goto buf_err;
      }
    }
  }              /* for (;*orig;) */

  if (idx > strlen(*value)) {
    free(*value);
    if ((*value = malloc(idx + 1)) == NULL) {
      D(("Couldn't malloc %d bytes for expanded var", idx + 1));
      pam_syslog (pamh, LOG_CRIT, "Couldn't malloc %lu bytes for expanded var",
	       (unsigned long)idx+1);
      goto buf_err;
    }
  }
  strcpy(*value, tmp);
  pam_overwrite_array(tmp);
  pam_overwrite_array(tmpval);
  D(("Exit."));

  return PAM_SUCCESS;
buf_err:
  pam_overwrite_array(tmp);
  pam_overwrite_array(tmpval);
  return PAM_BUF_ERR;
abort_err:
  pam_overwrite_array(tmp);
  pam_overwrite_array(tmpval);
  return PAM_ABORT;
}

static int
_check_var(pam_handle_t *pamh, VAR *var)
{
  /*
   * Examine the variable and determine what action to take.
   * Returns DEFINE_VAR, UNDEFINE_VAR depending on action to take
   * or a PAM_* error code if passed back from other routines
   *
   * if no DEFAULT provided, the empty string is assumed
   * if no OVERRIDE provided, the empty string is assumed
   * if DEFAULT=  and OVERRIDE evaluates to the empty string,
   *    this variable should be undefined
   * if DEFAULT=""  and OVERRIDE evaluates to the empty string,
   *    this variable should be defined with no value
   * if OVERRIDE=value   and value turns into the empty string, DEFAULT is used
   *
   * If DEFINE_VAR is to be returned, the correct value to define will
   * be pointed to by var->value
   */

  int retval;

  D(("Called."));

  /*
   * First thing to do is to expand any arguments, but only
   * if they are not the special quote values (cause expand_arg
   * changes memory).
   */

  if (var->defval && (&quote != var->defval) &&
      ((retval = _expand_arg(pamh, &(var->defval))) != PAM_SUCCESS)) {
      return retval;
  }
  if (var->override && (&quote != var->override) &&
      ((retval = _expand_arg(pamh, &(var->override))) != PAM_SUCCESS)) {
    return retval;
  }

  /* Now its easy */

  if (var->override && *(var->override)) {
    /* if there is a non-empty string in var->override, we use it */
    D(("OVERRIDE variable <%s> being used: <%s>", var->name, var->override));
    var->value = var->override;
    retval = DEFINE_VAR;
  } else {

    var->value = var->defval;
    if (&quote == var->defval) {
      /*
       * This means that the empty string was given for defval value
       * which indicates that a variable should be defined with no value
       */
      D(("An empty variable: <%s>", var->name));
      retval = DEFINE_VAR;
    } else if (var->defval) {
      D(("DEFAULT variable <%s> being used: <%s>", var->name, var->defval));
      retval = DEFINE_VAR;
    } else {
      D(("UNDEFINE variable <%s>", var->name));
      retval = UNDEFINE_VAR;
    }
  }

  D(("Exit."));
  return retval;
}

static void
_clean_var(VAR *var)
{
    if (var->name) {
      pam_overwrite_string(var->name);
      free(var->name);
    }
    if (var->defval && (&quote != var->defval)) {
      pam_overwrite_string(var->defval);
      free(var->defval);
    }
    if (var->override && (&quote != var->override)) {
      pam_overwrite_string(var->override);
      free(var->override);
    }
    var->name = NULL;
    var->value = NULL;    /* never has memory specific to it */
    var->defval = NULL;
    var->override = NULL;
    return;
}

static int
_define_var(pam_handle_t *pamh, int ctrl, VAR *var)
{
  /* We have a variable to define, this is a simple function */

  char *envvar;
  int retval = PAM_SUCCESS;

  D(("Called."));
  if (asprintf(&envvar, "%s=%s", var->name, var->value) < 0) {
    pam_syslog(pamh, LOG_CRIT, "out of memory");
    return PAM_BUF_ERR;
  }

  retval = pam_putenv(pamh, envvar);
  if (ctrl & PAM_DEBUG_ARG) {
    pam_syslog(pamh, LOG_DEBUG, "pam_putenv(\"%s\")", envvar);
  }
  _pam_drop(envvar);
  D(("Exit."));
  return retval;
}

static int
_undefine_var(pam_handle_t *pamh, int ctrl, VAR *var)
{
  /* We have a variable to undefine, this is a simple function */

  D(("Called and exit."));
  if (ctrl & PAM_DEBUG_ARG) {
    pam_syslog(pamh, LOG_DEBUG, "remove variable \"%s\"", var->name);
  }
  return pam_putenv(pamh, var->name);
}

static int
_parse_config_file(pam_handle_t *pamh, int ctrl, const char *file)
{
    int retval;
    VAR Var, *var=&Var;
    char **conf_list = NULL;

    var->name=NULL; var->defval=NULL; var->override=NULL;

    D(("Called."));

#ifdef USE_ECONF
    /* If "file" is not NULL, only this file will be parsed. */
    retval = econf_read_file(pamh, file, " \t", PAM_ENV, ".conf", "security", &conf_list);
#else
    /* Only one file will be parsed. So, file has to be set. */
    if (file == NULL) /* No filename has been set via argv. */
      file = DEFAULT_CONF_FILE;
#ifdef VENDOR_DEFAULT_CONF_FILE
    /*
    * Check whether file is available.
    * If it does not exist, fall back to VENDOR_DEFAULT_CONF_FILE file.
    */
    struct stat stat_buffer;
    if (stat(file, &stat_buffer) != 0 && errno == ENOENT) {
      file = VENDOR_DEFAULT_CONF_FILE;
    }
#endif
    retval = read_file(pamh, file, &conf_list);
#endif

    if (retval != PAM_SUCCESS)
      return retval;

    for (char **conf = conf_list; *conf != NULL; ++conf) {
      if ((retval = _parse_line(pamh, *conf, var)) == GOOD_LINE) {
	retval = _check_var(pamh, var);

	if (DEFINE_VAR == retval) {
	  retval = _define_var(pamh, ctrl, var);

	} else if (UNDEFINE_VAR == retval) {
	  retval = _undefine_var(pamh, ctrl, var);
	}
      }
      if (PAM_SUCCESS != retval && ILLEGAL_VAR != retval
	  && BAD_LINE != retval && PAM_BAD_ITEM != retval) break;

      _clean_var(var);

    }  /* for */

    /* tidy up */
    free_string_array(conf_list);
    _clean_var(var);        /* We could have got here prematurely,
			     * this is safe though */
    D(("Exit."));
    return (retval != 0 ? PAM_ABORT : PAM_SUCCESS);
}

static int
_parse_env_file(pam_handle_t *pamh, int ctrl, const char *file)
{
    int retval=PAM_SUCCESS, i, t;
    char *key, *mark;
    char **env_list = NULL;

#ifdef USE_ECONF
    retval = econf_read_file(pamh, file, "=", ENVIRONMENT, "", "", &env_list);
#else
    /* Only one file will be parsed. So, file has to be set. */
    if (file == NULL) /* No filename has been set via argv. */
      file = DEFAULT_ETC_ENVFILE;
#ifdef VENDOR_DEFAULT_ETC_ENVFILE
    /*
    * Check whether file is available.
    * If it does not exist, fall back to VENDOR_DEFAULT_ETC_ENVFILE; file.
    */
    struct stat stat_buffer;
    if (stat(file, &stat_buffer) != 0 && errno == ENOENT) {
      file = VENDOR_DEFAULT_ETC_ENVFILE;
    }
#endif
    retval = read_file(pamh, file, &env_list);
#endif

    if (retval != PAM_SUCCESS)
        return retval == PAM_IGNORE ? PAM_SUCCESS : retval;

    for (char **env = env_list; *env != NULL; ++env) {
        key = *env;

	/* skip leading white space */
	key += strspn(key, " \n\t");

	/* skip blanks lines and comments */
	if (key[0] == '#')
	    continue;

	/* skip over "export " if present so we can be compat with
	   bash type declarations */
	if (strncmp(key, "export ", (size_t) 7) == 0)
	    key += 7;

	/* now find the end of value */
	mark = key;
	while(mark[0] != '\n' && mark[0] != '#' && mark[0] != '\0')
	    mark++;
	if (mark[0] != '\0')
	    mark[0] = '\0';

       /*
	* sanity check, the key must be alphanumeric
	*/

	if (key[0] == '=') {
		pam_syslog(pamh, LOG_ERR,
		           "missing key name '%s' in %s', ignoring",
		           key, file);
		continue;
	}

	for ( i = 0 ; key[i] != '=' && key[i] != '\0' ; i++ )
	    if (!isalnum(key[i]) && key[i] != '_') {
		pam_syslog(pamh, LOG_ERR,
		           "non-alphanumeric key '%s' in %s', ignoring",
		           key, file);
		break;
	    }
	/* non-alphanumeric key, ignore this line */
	if (key[i] != '=' && key[i] != '\0')
	    continue;

	/* now we try to be smart about quotes around the value,
	   but not too smart, we can't get all fancy with escaped
	   values like bash */
	if (key[i] == '=' && (key[++i] == '\"' || key[i] == '\'')) {
	    for ( t = i+1 ; key[t] != '\0' ; t++)
		if (key[t] != '\"' && key[t] != '\'')
		    key[i++] = key[t];
		else if (key[t+1] != '\0')
		    key[i++] = key[t];
	    key[i] = '\0';
	}

	/* if this is a request to delete a variable, check that it's
	   actually set first, so we don't get a vague error back from
	   pam_putenv() */
	for (i = 0; key[i] != '=' && key[i] != '\0'; i++);

	if (key[i] == '\0' && !pam_getenv(pamh,key))
	    continue;

	/* set the env var, if it fails, we break out of the loop */
	retval = pam_putenv(pamh, key);
	if (retval != PAM_SUCCESS) {
	    D(("error setting env \"%s\"", key));
	    break;
	} else if (ctrl & PAM_DEBUG_ARG) {
	    pam_syslog(pamh, LOG_DEBUG,
		       "pam_putenv(\"%s\")", key);
	}
    }

    /* tidy up */
    free_string_array(env_list);
    D(("Exit."));
    return retval;
}

/* --- authentication management functions (only) --- */

int
pam_sm_authenticate (pam_handle_t *pamh UNUSED, int flags UNUSED,
		     int argc UNUSED, const char **argv UNUSED)
{
  return PAM_IGNORE;
}

static int
handle_env (pam_handle_t *pamh, int argc, const char **argv)
{
  int retval, ctrl, readenv=DEFAULT_READ_ENVFILE;
  int user_readenv = DEFAULT_USER_READ_ENVFILE;
  const char *conf_file = NULL, *env_file = NULL, *user_env_file = NULL;

  /*
   * this module sets environment variables read in from a file
   */

  D(("Called."));
  ctrl = _pam_parse(pamh, argc, argv, &conf_file, &env_file,
		    &readenv, &user_env_file, &user_readenv);

  retval = _parse_config_file(pamh, ctrl, conf_file);

  if(readenv && retval == PAM_SUCCESS) {
    retval = _parse_env_file(pamh, ctrl, env_file);
    if (retval == PAM_IGNORE)
      retval = PAM_SUCCESS;
  }

  if(user_readenv && retval == PAM_SUCCESS) {
    char *envpath = NULL;
    struct passwd *user_entry = NULL;
    const char *username;
    struct stat statbuf;

    username = _pam_get_item_byname(pamh, "PAM_USER");

    if (username)
      user_entry = pam_modutil_getpwnam (pamh, username);
    if (!user_entry) {
      pam_syslog(pamh, LOG_ERR, "No such user!?");
    }
    else {
      if (asprintf(&envpath, "%s/%s", user_entry->pw_dir, user_env_file) < 0)
	{
	  pam_syslog(pamh, LOG_CRIT, "Out of memory");
	  return PAM_BUF_ERR;
	}
      if (stat(envpath, &statbuf) == 0) {
	PAM_MODUTIL_DEF_PRIVS(privs);

	if (pam_modutil_drop_priv(pamh, &privs, user_entry)) {
	  retval = PAM_SESSION_ERR;
	} else {
	  retval = _parse_config_file(pamh, ctrl, envpath);
	  if (pam_modutil_regain_priv(pamh, &privs))
	    retval = PAM_SESSION_ERR;
	}
        if (retval == PAM_IGNORE)
          retval = PAM_SUCCESS;
      }
      free(envpath);
    }
  }

  /* indicate success or failure */
  D(("Exit."));
  return retval;
}

int
pam_sm_acct_mgmt (pam_handle_t *pamh UNUSED, int flags UNUSED,
		  int argc UNUSED, const char **argv UNUSED)
{
  pam_syslog (pamh, LOG_NOTICE, "pam_sm_acct_mgmt called inappropriately");
  return PAM_SERVICE_ERR;
}

int
pam_sm_setcred (pam_handle_t *pamh, int flags UNUSED,
		int argc, const char **argv)
{
  D(("Called"));
  return handle_env (pamh, argc, argv);
}

int
pam_sm_open_session (pam_handle_t *pamh, int flags UNUSED,
		     int argc, const char **argv)
{
  D(("Called"));
  return handle_env (pamh, argc, argv);
}

int
pam_sm_close_session (pam_handle_t *pamh UNUSED, int flags UNUSED,
		      int argc UNUSED, const char **argv UNUSED)
{
  D(("Called and Exit"));
  return PAM_SUCCESS;
}

int
pam_sm_chauthtok (pam_handle_t *pamh UNUSED, int flags UNUSED,
		  int argc UNUSED, const char **argv UNUSED)
{
  pam_syslog (pamh, LOG_NOTICE, "pam_sm_chauthtok called inappropriately");
  return PAM_SERVICE_ERR;
}

/* end of module definition */