summary refs log tree commit diff
path: root/nss/nsswitch.c
blob: 1b061fa3cd1225bdc63b72671021a4f3d6486e19 (plain) (blame)
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
/* Copyright (C) 1996 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <ctype.h>
#include <dlfcn.h>
#include <errno.h>
#include <netdb.h>
#include <libc-lock.h>
#include <link.h>	/* We need some help from ld.so.  */
#include <search.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "nsswitch.h"

/* Prototypes for the local functions.  */
static void *nss_lookup_function (service_user *ni, const char *fct_name);
static name_database *nss_parse_file (const char *fname);
static name_database_entry *nss_getline (char *line);
static service_user *nss_parse_service_list (const char *line);
static service_library *nss_new_service (name_database *database,
					 const char *name);


/* Declare external database variables.  */
#define DEFINE_DATABASE(name)						      \
  extern service_user *__nss_##name##_database;				      \
  weak_extern (__nss_##name##_database)
#include "databases.def"
#undef DEFINE_DATABASE

/* Structure to map database name to variable.  */
static struct
{
  const char *name;
  service_user **dbp;
} databases[] =
{
#define DEFINE_DATABASE(name)						      \
  { #name, &__nss_##name##_database },
#include "databases.def"
#undef DEFINE_DATABASE
};


__libc_lock_define_initialized (static, lock)


/* Nonzero if the sevices are already initialized.  */
static int nss_initialized;


/* The root of the whole data base.  */
static name_database *service_table;


/* -1 == database not found
    0 == database entry pointer stored */
int
__nss_database_lookup (const char *database, const char *alternate_name,
		       const char *defconfig, service_user **ni)
{
  /* Prevent multiple threads to change the service table.  */
  __libc_lock_lock (lock);

  /* Reconsider database variable in case some other thread called
     `__nss_configure_lookup' while we waited for the lock.  */
  if (*ni != NULL)
    {
      __libc_lock_unlock (lock);
      return 0;
    }

  if (nss_initialized == 0 && service_table == NULL)
    /* Read config file.  */
    service_table = nss_parse_file (_PATH_NSSWITCH_CONF);

  /* Test whether configuration data is available.  */
  if (service_table != NULL)
    {
      /* Return first `service_user' entry for DATABASE.  */
      name_database_entry *entry;

      /* XXX Could use some faster mechanism here.  But each database is
	 only requested once and so this might not be critical.  */
      for (entry = service_table->entry; entry != NULL; entry = entry->next)
	if (strcmp (database, entry->name) == 0)
	  *ni = entry->service;

      if (*ni == NULL && alternate_name != NULL)
	/* We haven't found a an entry so far.  Try to find it with
	   the alternative name.  */
	for (entry = service_table->entry; entry != NULL; entry = entry->next)
	  if (strcmp (alternate_name, entry->name) == 0)
	    *ni = entry->service;
    }

  /* No configuration data is available, either because nsswitch.conf
     doesn't exist or because it doesn't has a line for this database.

     DEFCONFIG specifies the default service list for this database,
     or null to use the most common default.  */
  if (*ni == NULL)
    *ni = nss_parse_service_list (defconfig
				  ?: "nis [NOTFOUND=return] files");

  __libc_lock_unlock (lock);

  return 0;
}


/* -1 == not found
    0 == adjusted for next function */
int
__nss_lookup (service_user **ni, const char *fct_name, void **fctp)
{
  *fctp = nss_lookup_function (*ni, fct_name);

  while (*fctp == NULL
	 && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
	 && (*ni)->next != NULL)
    {
      *ni = (*ni)->next;

      *fctp = nss_lookup_function (*ni, fct_name);
    }

  return *fctp != NULL ? 0 : -1;
}


/* -1 == not found
    0 == adjusted for next function
    1 == finished */
int
__nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
	    int all_values)
{
  if (all_values)
    {
      if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
	  && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
	  && nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
	  && nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
	return 1;
    }
  else
    {
      /* This is really only for debugging.  */
       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
	 __libc_fatal ("illegal status in " __FUNCTION__);

       if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
	 return 1;
    }

  if ((*ni)->next == NULL)
    return -1;

  do
    {
      *ni = (*ni)->next;

      *fctp = nss_lookup_function (*ni, fct_name);
    }
  while (*fctp == NULL
	 && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
	 && (*ni)->next != NULL);

  return *fctp != NULL ? 0 : -1;
}


int
__nss_configure_lookup (const char *dbname, const char *service_line)
{
  service_user *new_db;
  size_t cnt;

  for (cnt = 0; cnt < sizeof databases; ++cnt)
    {
      int cmp = strcmp (dbname, databases[cnt].name);
      if (cmp == 0)
	break;
      if (cmp > 0)
	{
	  __set_errno (EINVAL);
	  return -1;
	}
    }

  if (cnt == sizeof databases)
    {
      __set_errno (EINVAL);
      return -1;
    }

  /* Test whether it is really used.  */
  if (databases[cnt].dbp == NULL)
    /* Nothing to do, but we could do.  */
    return 0;

  /* Try to generate new data.  */
  new_db = nss_parse_service_list (service_line);
  if (new_db == NULL)
    {
      /* Illegal service specification.  */
      __set_errno (EINVAL);
      return -1;
    }

  /* Prevent multiple threads to change the service table.  */
  __libc_lock_lock (lock);

  /* Install new rules.  */
  *databases[cnt].dbp = new_db;

  __libc_lock_unlock (lock);

  return 0;
}


static int
nss_dlerror_run (void (*operate) (void))
{
  char *last_errstring = NULL;
  const char *last_object_name = NULL;
  int result;

  (void) _dl_catch_error (&last_errstring, &last_object_name, operate);

  result = last_errstring != NULL;
  if (result)
    free (last_errstring);

  return result;
}


/* Comparison function for searching NI->known tree.  */
static int
known_compare (const void *p1, const void *p2)
{
  return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
				*(const char *const *) p2);
}


static void *
nss_lookup_function (service_user *ni, const char *fct_name)
{
  void **found, *result;

  /* We now modify global data.  Protect it.  */
  __libc_lock_lock (lock);

  /* Search the tree of functions previously requested.  Data in the
     tree are `known_function' structures, whose first member is a
     `const char *', the lookup key.  The search returns a pointer to
     the tree node structure; the first member of the is a pointer to
     our structure (i.e. what will be a `known_function'); since the
     first member of that is the lookup key string, &FCT_NAME is close
     enough to a pointer to our structure to use as a lookup key that
     will be passed to `known_compare' (above).  */

  found = __tsearch (&fct_name, (void **) &ni->known, &known_compare);
  if (*found != &fct_name)
    /* The search found an existing structure in the tree.  */
    result = ((known_function *) *found)->fct_ptr;
  else
    {
      /* This name was not known before.  Now we have a node in the tree
	 (in the proper sorted position for FCT_NAME) that points to
	 &FCT_NAME instead of any real `known_function' structure.
	 Allocate a new structure and fill it in.  */

      known_function *known = malloc (sizeof *known);
      if (! known)
	{
	remove_from_tree:
	  /* Oops.  We can't instantiate this node properly.
	     Remove it from the tree.  */
	  __tdelete (&fct_name, (void **) &ni->known, &known_compare);
	  result = NULL;
	}
      else
	{
	  /* Point the tree node at this new structure.  */
	  *found = known;
	  known->fct_name = fct_name;

	  if (ni->library == NULL)
	    {
	      /* This service has not yet been used.  Fetch the service
		 library for it, creating a new one if need be.  If there
		 is no service table from the file, this static variable
		 holds the head of the service_library list made from the
		 default configuration.  */
	      static name_database default_table;
	      ni->library = nss_new_service (service_table ?: &default_table,
					     ni->name);
	      if (ni->library == NULL)
		{
		  /* This only happens when out of memory.  */
		  free (known);
		  goto remove_from_tree;
		}
	    }

	  if (ni->library->lib_handle == NULL)
	    {
	      /* Load the shared library.  */
	      size_t shlen = (7 + strlen (ni->library->name) + 3
			      + sizeof (NSS_SHLIB_REVISION));
	      char shlib_name[shlen];

	      void do_open (void)
		{
		  /* Open and relocate the shared object.  */
		  ni->library->lib_handle = _dl_open (shlib_name, RTLD_LAZY);
		}

	      /* Construct shared object name.  */
	      __stpcpy (__stpcpy (__stpcpy (shlib_name, "libnss_"),
				  ni->library->name),
			".so" NSS_SHLIB_REVISION);

	      if (nss_dlerror_run (do_open) != 0)
		/* Failed to load the library.  */
		ni->library->lib_handle = (void *) -1l;
	    }

	  if (ni->library->lib_handle == (void *) -1l)
	    /* Library not found => function not found.  */
	    result = NULL;
	  else
	    {
	      /* Get the desired function.  Again,  GNU ld.so magic ahead.  */
	      size_t namlen = (5 + strlen (ni->library->name) + 1
			       + strlen (fct_name) + 1);
	      char name[namlen];
	      struct link_map *map = ni->library->lib_handle;
	      ElfW(Addr) loadbase;
	      const ElfW(Sym) *ref = NULL;
	      void get_sym (void)
		{
		  struct link_map *scope[2] = { map, NULL };
		  loadbase = _dl_lookup_symbol (name, &ref,
						scope, map->l_name, 0);
		}

	      /* Construct the function name.  */
	      __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
					    ni->library->name),
				  "_"),
			fct_name);

	      /* Look up the symbol.  */
	      result = (nss_dlerror_run (get_sym)
			? NULL : (void *) (loadbase + ref->st_value));
	    }

	  /* Remember function pointer for later calls.  Even if null, we
	     record it so a second try needn't search the library again.  */
	  known->fct_ptr = result;
	}
    }

  /* Remove the lock.  */
  __libc_lock_unlock (lock);

  return result;
}


static name_database *
nss_parse_file (const char *fname)
{
  FILE *fp;
  name_database *result;
  name_database_entry *last;
  char *line;
  size_t len;

  /* Open the configuration file.  */
  fp = fopen (fname, "r");
  if (fp == NULL)
    return NULL;

  result = (name_database *) malloc (sizeof (name_database));
  if (result == NULL)
    return NULL;

  result->entry = NULL;
  result->library = NULL;
  last = NULL;
  line = NULL;
  len = 0;
  do
    {
      name_database_entry *this;
      ssize_t n;
      char *cp;

      n = __getline (&line, &len, fp);
      if (n < 0)
	break;
      if (line[n - 1] == '\n')
	line[n - 1] = '\0';

      /* Because the file format does not know any form of quoting we
	 can search forward for the next '#' character and if found
	 make it terminating the line.  */
      cp = strchr (line, '#');
      if (cp != NULL)
	*cp = '\0';

      /* If the line is blank it is ignored.  */
      if (line[0] == '\0')
	continue;

      /* Each line completely specifies the actions for a database.  */
      this = nss_getline (line);
      if (this != NULL)
	{
	  if (last != NULL)
	    last->next = this;
	  else
	    result->entry = this;

	  last = this;
	}
    }
  while (!feof (fp));

  /* Free the buffer.  */
  free (line);
  /* Close configuration file.  */
  fclose (fp);

  return result;
}


/* Read the source names:
	`( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
   */
static service_user *
nss_parse_service_list (const char *line)
{
  service_user *result = NULL, **nextp = &result;

  while (1)
    {
      service_user *new_service;
      const char *name;

      while (isspace (line[0]))
	++line;
      if (line[0] == '\0')
	/* No source specified.  */
	return result;

      /* Read <source> identifier.  */
      name = line;
      while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
	++line;
      if (name == line)
	return result;


      new_service = (service_user *) malloc (sizeof (service_user));
      if (new_service == NULL)
	return result;
      else
	{
	  char *source = (char *) malloc (line - name + 1);
	  if (source == NULL)
	    {
	      free (new_service);
	      return result;
	    }
	  memcpy (source, name, line - name);
	  source[line - name] = '\0';

	  new_service->name = source;
	}

      /* Set default actions.  */
      new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
      new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
      new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
      new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
      new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
      new_service->library = NULL;
      new_service->known = NULL;
      new_service->next = NULL;

      while (isspace (line[0]))
	++line;

      if (line[0] == '[')
	{
	  /* Read criterions.  */
	  do
	    ++line;
	  while (line[0] != '\0' && isspace (line[0]));

	  do
	    {
	      int not;
	      enum nss_status status;
	      lookup_actions action;

	      /* Grok ! before name to mean all statii but that one.  */
	      if (not = line[0] == '!')
		++line;

	      /* Read status name.  */
	      name = line;
	      while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
		     && line[0] != ']')
		++line;

	      /* Compare with known statii.  */
	      if (line - name == 7)
		{
		  if (__strncasecmp (name, "SUCCESS", 7) == 0)
		    status = NSS_STATUS_SUCCESS;
		  else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
		    status = NSS_STATUS_UNAVAIL;
		  else
		    return result;
		}
	      else if (line - name == 8)
		{
		  if (__strncasecmp (name, "NOTFOUND", 8) == 0)
		    status = NSS_STATUS_NOTFOUND;
		  else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
		    status = NSS_STATUS_TRYAGAIN;
		  else
		    return result;
		}
	      else
		return result;

	      while (isspace (line[0]))
		++line;
	      if (line[0] != '=')
		return result;
	      do
		++line;
	      while (isspace (line[0]));

	      name = line;
	      while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
		     && line[0] != ']')
		++line;

	      if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
		action = NSS_ACTION_RETURN;
	      else if (line - name == 8
		       && __strncasecmp (name, "CONTINUE", 8) == 0)
		action = NSS_ACTION_CONTINUE;
	      else
		return result;

	      if (not)
		{
		  /* Save the current action setting for this status,
		     set them all to the given action, and reset this one.  */
		  const lookup_actions save = new_service->actions[2 + status];
		  new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
		  new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
		  new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
		  new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
		  new_service->actions[2 + status] = save;
		}
	      else
		new_service->actions[2 + status] = action;

	      /* Skip white spaces.  */
	      while (isspace (line[0]))
		++line;
	    }
	  while (line[0] != ']');

	  /* Skip the ']'.  */
	  ++line;
	}

      *nextp = new_service;
      nextp = &new_service->next;
    }
}

static name_database_entry *
nss_getline (char *line)
{
  const char *name;
  name_database_entry *result;

  /* Ignore leading white spaces.  ATTENTION: this is different from
     what is implemented in Solaris.  The Solaris man page says a line
     beginning with a white space character is ignored.  We regard
     this as just another misfeature in Solaris.  */
  while (isspace (line[0]))
    ++line;

  /* Recognize `<database> ":"'.  */
  name = line;
  while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
    ++line;
  if (line[0] == '\0' || name == line)
    /* Syntax error.  */
    return NULL;
  *line++ = '\0';

  result = (name_database_entry *) malloc (sizeof (name_database_entry));
  if (result == NULL)
    return NULL;

  /* Save the database name.  */
  {
    const size_t len = strlen (name) + 1;
    char *new = malloc (len);
    if (new == NULL)
      {
	free (result);
	return NULL;
      }
    result->name = memcpy (new, name, len);
  }

  /* Parse the list of services.  */
  result->service = nss_parse_service_list (line);

  result->next = NULL;
  return result;
}


static service_library *
nss_new_service (name_database *database, const char *name)
{
  service_library **currentp = &database->library;

  while (*currentp != NULL)
    {
      if (strcmp ((*currentp)->name, name) == 0)
	return *currentp;
      currentp = &(*currentp)->next;
    }

  /* We have to add the new service.  */
  *currentp = (service_library *) malloc (sizeof (service_library));
  if (*currentp == NULL)
    return NULL;

  (*currentp)->name = name;
  (*currentp)->lib_handle = NULL;
  (*currentp)->next = NULL;

  return *currentp;
}