nss/nsswitch.c

   1 /* Copyright (C) 1996,1997,1998,1999,2001,2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <ctype.h>
  21 #include <dlfcn.h>
  22 #include <errno.h>
  23 #include <netdb.h>
  24 #include <bits/libc-lock.h>
  25 #include <search.h>
  26 #include <stdio.h>
  27 #include <stdio_ext.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30
  31 #include <aliases.h>
  32 #include <grp.h>
  33 #include <netinet/ether.h>
  34 #include <pwd.h>
  35 #include <shadow.h>
  36
  37 #if !defined DO_STATIC_NSS || defined SHARED
  38 # include <gnu/lib-names.h>
  39 #endif
  40
  41 #include "nsswitch.h"
  42
  43 /* Prototypes for the local functions.  */
  44 static name_database *nss_parse_file (const char *fname) internal_function;
  45 static name_database_entry *nss_getline (char *line) internal_function;
  46 static service_user *nss_parse_service_list (const char *line)
  47      internal_function;
  48 static service_library *nss_new_service (name_database *database,
  49                                          const char *name) internal_function;
  50
  51
  52 /* Declare external database variables.  */
  53 #define DEFINE_DATABASE(name)                                                 \
  54   extern service_user *__nss_##name##_database attribute_hidden;              \
  55   weak_extern (__nss_##name##_database)
  56 #include "databases.def"
  57 #undef DEFINE_DATABASE
  58
  59 /* Structure to map database name to variable.  */
  60 static struct
  61 {
  62   const char *name;
  63   service_user **dbp;
  64 } databases[] =
  65 {
  66 #define DEFINE_DATABASE(name)                                                 \
  67   { #name, &__nss_##name##_database },
  68 #include "databases.def"
  69 #undef DEFINE_DATABASE
  70 };
  71
  72
  73 __libc_lock_define_initialized (static, lock)
  74
  75 #if !defined DO_STATIC_NSS || defined SHARED
  76 /* String with revision number of the shared object files.  */
  77 static const char *const __nss_shlib_revision = LIBNSS_FILES_SO + 15;
  78 #endif
  79
  80 /* The root of the whole data base.  */
  81 static name_database *service_table;
  82
  83
  84 /* -1 == database not found
  85     0 == database entry pointer stored */
  86 int
  87 __nss_database_lookup (const char *database, const char *alternate_name,
  88                        const char *defconfig, service_user **ni)
  89 {
  90   /* Prevent multiple threads to change the service table.  */
  91   __libc_lock_lock (lock);
  92
  93   /* Reconsider database variable in case some other thread called
  94      `__nss_configure_lookup' while we waited for the lock.  */
  95   if (*ni != NULL)
  96     {
  97       __libc_lock_unlock (lock);
  98       return 0;
  99     }
 100
 101   /* Are we initialized yet?  */
 102   if (service_table == NULL)
 103     /* Read config file.  */
 104     service_table = nss_parse_file (_PATH_NSSWITCH_CONF);
 105
 106   /* Test whether configuration data is available.  */
 107   if (service_table != NULL)
 108     {
 109       /* Return first `service_user' entry for DATABASE.  */
 110       name_database_entry *entry;
 111
 112       /* XXX Could use some faster mechanism here.  But each database is
 113          only requested once and so this might not be critical.  */
 114       for (entry = service_table->entry; entry != NULL; entry = entry->next)
 115         if (strcmp (database, entry->name) == 0)
 116           *ni = entry->service;
 117
 118       if (*ni == NULL && alternate_name != NULL)
 119         /* We haven't found an entry so far.  Try to find it with the
 120            alternative name.  */
 121         for (entry = service_table->entry; entry != NULL; entry = entry->next)
 122           if (strcmp (alternate_name, entry->name) == 0)
 123             *ni = entry->service;
 124     }
 125
 126   /* No configuration data is available, either because nsswitch.conf
 127      doesn't exist or because it doesn't has a line for this database.
 128
 129      DEFCONFIG specifies the default service list for this database,
 130      or null to use the most common default.  */
 131   if (*ni == NULL)
 132     *ni = nss_parse_service_list (defconfig
 133                                   ?: "nis [NOTFOUND=return] files");
 134
 135   __libc_lock_unlock (lock);
 136
 137   return 0;
 138 }
 139 libc_hidden_def (__nss_database_lookup)
 140
 141
 142 /* -1 == not found
 143     0 == function found
 144     1 == finished */
 145 int
 146 __nss_lookup (service_user **ni, const char *fct_name, void **fctp)
 147 {
 148   *fctp = __nss_lookup_function (*ni, fct_name);
 149
 150   while (*fctp == NULL
 151          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 152          && (*ni)->next != NULL)
 153     {
 154       *ni = (*ni)->next;
 155
 156       *fctp = __nss_lookup_function (*ni, fct_name);
 157     }
 158
 159   return *fctp != NULL ? 0 : (*ni)->next == NULL ? 1 : -1;
 160 }
 161
 162
 163 /* -1 == not found
 164     0 == adjusted for next function
 165     1 == finished */
 166 int
 167 __nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
 168             int all_values)
 169 {
 170   if (all_values)
 171     {
 172       if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
 173           && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
 174           && nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
 175           && nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
 176         return 1;
 177     }
 178   else
 179     {
 180       /* This is really only for debugging.  */
 181        if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 182          __libc_fatal ("illegal status in __nss_next");
 183
 184        if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
 185          return 1;
 186     }
 187
 188   if ((*ni)->next == NULL)
 189     return -1;
 190
 191   do
 192     {
 193       *ni = (*ni)->next;
 194
 195       *fctp = __nss_lookup_function (*ni, fct_name);
 196     }
 197   while (*fctp == NULL
 198          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 199          && (*ni)->next != NULL);
 200
 201   return *fctp != NULL ? 0 : -1;
 202 }
 203 libc_hidden_def (__nss_next)
 204
 205
 206 int
 207 __nss_configure_lookup (const char *dbname, const char *service_line)
 208 {
 209   service_user *new_db;
 210   size_t cnt;
 211
 212   for (cnt = 0; cnt < sizeof databases; ++cnt)
 213     {
 214       int cmp = strcmp (dbname, databases[cnt].name);
 215       if (cmp == 0)
 216         break;
 217       if (cmp < 0)
 218         {
 219           __set_errno (EINVAL);
 220           return -1;
 221         }
 222     }
 223
 224   if (cnt == sizeof databases)
 225     {
 226       __set_errno (EINVAL);
 227       return -1;
 228     }
 229
 230   /* Test whether it is really used.  */
 231   if (databases[cnt].dbp == NULL)
 232     /* Nothing to do, but we could do.  */
 233     return 0;
 234
 235   /* Try to generate new data.  */
 236   new_db = nss_parse_service_list (service_line);
 237   if (new_db == NULL)
 238     {
 239       /* Illegal service specification.  */
 240       __set_errno (EINVAL);
 241       return -1;
 242     }
 243
 244   /* Prevent multiple threads to change the service table.  */
 245   __libc_lock_lock (lock);
 246
 247   /* Install new rules.  */
 248   *databases[cnt].dbp = new_db;
 249
 250   __libc_lock_unlock (lock);
 251
 252   return 0;
 253 }
 254
 255
 256 /* Comparison function for searching NI->known tree.  */
 257 static int
 258 known_compare (const void *p1, const void *p2)
 259 {
 260   return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
 261                                 *(const char *const *) p2);
 262 }
 263
 264
 265 void *
 266 __nss_lookup_function (service_user *ni, const char *fct_name)
 267 {
 268   void **found, *result;
 269
 270   /* We now modify global data.  Protect it.  */
 271   __libc_lock_lock (lock);
 272
 273   /* Search the tree of functions previously requested.  Data in the
 274      tree are `known_function' structures, whose first member is a
 275      `const char *', the lookup key.  The search returns a pointer to
 276      the tree node structure; the first member of the is a pointer to
 277      our structure (i.e. what will be a `known_function'); since the
 278      first member of that is the lookup key string, &FCT_NAME is close
 279      enough to a pointer to our structure to use as a lookup key that
 280      will be passed to `known_compare' (above).  */
 281
 282   found = __tsearch (&fct_name, (void **) &ni->known, &known_compare);
 283   if (*found != &fct_name)
 284     /* The search found an existing structure in the tree.  */
 285     result = ((known_function *) *found)->fct_ptr;
 286   else
 287     {
 288       /* This name was not known before.  Now we have a node in the tree
 289          (in the proper sorted position for FCT_NAME) that points to
 290          &FCT_NAME instead of any real `known_function' structure.
 291          Allocate a new structure and fill it in.  */
 292
 293       known_function *known = malloc (sizeof *known);
 294       if (! known)
 295         {
 296         remove_from_tree:
 297           /* Oops.  We can't instantiate this node properly.
 298              Remove it from the tree.  */
 299           __tdelete (&fct_name, (void **) &ni->known, &known_compare);
 300           result = NULL;
 301         }
 302       else
 303         {
 304           /* Point the tree node at this new structure.  */
 305           *found = known;
 306           known->fct_name = fct_name;
 307
 308           if (ni->library == NULL)
 309             {
 310               /* This service has not yet been used.  Fetch the service
 311                  library for it, creating a new one if need be.  If there
 312                  is no service table from the file, this static variable
 313                  holds the head of the service_library list made from the
 314                  default configuration.  */
 315               static name_database default_table;
 316               ni->library = nss_new_service (service_table ?: &default_table,
 317                                              ni->name);
 318               if (ni->library == NULL)
 319                 {
 320                   /* This only happens when out of memory.  */
 321                   free (known);
 322                   goto remove_from_tree;
 323                 }
 324             }
 325
 326 #if !defined DO_STATIC_NSS || defined SHARED
 327           if (ni->library->lib_handle == NULL)
 328             {
 329               /* Load the shared library.  */
 330               size_t shlen = (7 + strlen (ni->library->name) + 3
 331                               + strlen (__nss_shlib_revision) + 1);
 332               int saved_errno = errno;
 333               char shlib_name[shlen];
 334
 335               /* Construct shared object name.  */
 336               __stpcpy (__stpcpy (__stpcpy (__stpcpy (shlib_name,
 337                                                       "libnss_"),
 338                                             ni->library->name),
 339                                   ".so"),
 340                         __nss_shlib_revision);
 341
 342               ni->library->lib_handle = __libc_dlopen (shlib_name);
 343               if (ni->library->lib_handle == NULL)
 344                 {
 345                   /* Failed to load the library.  */
 346                   ni->library->lib_handle = (void *) -1l;
 347                   __set_errno (saved_errno);
 348                 }
 349             }
 350
 351           if (ni->library->lib_handle == (void *) -1l)
 352             /* Library not found => function not found.  */
 353             result = NULL;
 354           else
 355             {
 356               /* Get the desired function.  */
 357               size_t namlen = (5 + strlen (ni->library->name) + 1
 358                                + strlen (fct_name) + 1);
 359               char name[namlen];
 360
 361               /* Construct the function name.  */
 362               __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
 363                                             ni->library->name),
 364                                   "_"),
 365                         fct_name);
 366
 367               /* Look up the symbol.  */
 368               result = __libc_dlsym (ni->library->lib_handle, name);
 369             }
 370 #else
 371           /* We can't get function address dynamically in static linking. */
 372           {
 373 # define DEFINE_ENT(h,nm)                                                     \
 374             { #h"_get"#nm"ent_r", _nss_##h##_get##nm##ent_r },                \
 375             { #h"_end"#nm"ent", _nss_##h##_end##nm##ent },                    \
 376             { #h"_set"#nm"ent", _nss_##h##_set##nm##ent },
 377 # define DEFINE_GET(h,nm)                                                     \
 378             { #h"_get"#nm"_r", _nss_##h##_get##nm##_r },
 379 # define DEFINE_GETBY(h,nm,ky)                                                \
 380             { #h"_get"#nm"by"#ky"_r", _nss_##h##_get##nm##by##ky##_r },
 381             static struct fct_tbl { const char *fname; void *fp; } *tp, tbl[] =
 382               {
 383 # include "function.def"
 384                 { NULL, NULL }
 385               };
 386             size_t namlen = (5 + strlen (ni->library->name) + 1
 387                              + strlen (fct_name) + 1);
 388             char name[namlen];
 389
 390             /* Construct the function name.  */
 391             __stpcpy (__stpcpy (__stpcpy (name, ni->library->name),
 392                                 "_"),
 393                       fct_name);
 394
 395             result = NULL;
 396             for (tp = &tbl[0]; tp->fname; tp++)
 397               if (strcmp (tp->fname, name) == 0)
 398                 {
 399                   result = tp->fp;
 400                   break;
 401                 }
 402           }
 403 #endif
 404
 405           /* Remember function pointer for later calls.  Even if null, we
 406              record it so a second try needn't search the library again.  */
 407           known->fct_ptr = result;
 408         }
 409     }
 410
 411   /* Remove the lock.  */
 412   __libc_lock_unlock (lock);
 413
 414   return result;
 415 }
 416
 417
 418 static name_database *
 419 internal_function
 420 nss_parse_file (const char *fname)
 421 {
 422   FILE *fp;
 423   name_database *result;
 424   name_database_entry *last;
 425   char *line;
 426   size_t len;
 427
 428   /* Open the configuration file.  */
 429   fp = fopen (fname, "r");
 430   if (fp == NULL)
 431     return NULL;
 432
 433   /* No threads use this stream.  */
 434   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 435
 436   result = (name_database *) malloc (sizeof (name_database));
 437   if (result == NULL)
 438     return NULL;
 439
 440   result->entry = NULL;
 441   result->library = NULL;
 442   last = NULL;
 443   line = NULL;
 444   len = 0;
 445   do
 446     {
 447       name_database_entry *this;
 448       ssize_t n;
 449
 450       n = __getline (&line, &len, fp);
 451       if (n < 0)
 452         break;
 453       if (line[n - 1] == '\n')
 454         line[n - 1] = '\0';
 455
 456       /* Because the file format does not know any form of quoting we
 457          can search forward for the next '#' character and if found
 458          make it terminating the line.  */
 459       *__strchrnul (line, '#') = '\0';
 460
 461       /* If the line is blank it is ignored.  */
 462       if (line[0] == '\0')
 463         continue;
 464
 465       /* Each line completely specifies the actions for a database.  */
 466       this = nss_getline (line);
 467       if (this != NULL)
 468         {
 469           if (last != NULL)
 470             last->next = this;
 471           else
 472             result->entry = this;
 473
 474           last = this;
 475         }
 476     }
 477   while (!feof_unlocked (fp));
 478
 479   /* Free the buffer.  */
 480   free (line);
 481   /* Close configuration file.  */
 482   fclose (fp);
 483
 484   return result;
 485 }
 486
 487
 488 /* Read the source names:
 489         `( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
 490    */
 491 static service_user *
 492 internal_function
 493 nss_parse_service_list (const char *line)
 494 {
 495   service_user *result = NULL, **nextp = &result;
 496
 497   while (1)
 498     {
 499       service_user *new_service;
 500       const char *name;
 501
 502       while (isspace (line[0]))
 503         ++line;
 504       if (line[0] == '\0')
 505         /* No source specified.  */
 506         return result;
 507
 508       /* Read <source> identifier.  */
 509       name = line;
 510       while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
 511         ++line;
 512       if (name == line)
 513         return result;
 514
 515
 516       new_service = (service_user *) malloc (sizeof (service_user)
 517                                              + (line - name + 1));
 518       if (new_service == NULL)
 519         return result;
 520
 521       *((char *) __mempcpy (new_service->name, name, line - name)) = '\0';
 522
 523       /* Set default actions.  */
 524       new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
 525       new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
 526       new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
 527       new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
 528       new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
 529       new_service->library = NULL;
 530       new_service->known = NULL;
 531       new_service->next = NULL;
 532
 533       while (isspace (line[0]))
 534         ++line;
 535
 536       if (line[0] == '[')
 537         {
 538           /* Read criterions.  */
 539           do
 540             ++line;
 541           while (line[0] != '\0' && isspace (line[0]));
 542
 543           do
 544             {
 545               int not;
 546               enum nss_status status;
 547               lookup_actions action;
 548
 549               /* Grok ! before name to mean all statii but that one.  */
 550               not = line[0] == '!';
 551               if (not)
 552                 ++line;
 553
 554               /* Read status name.  */
 555               name = line;
 556               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 557                      && line[0] != ']')
 558                 ++line;
 559
 560               /* Compare with known statii.  */
 561               if (line - name == 7)
 562                 {
 563                   if (__strncasecmp (name, "SUCCESS", 7) == 0)
 564                     status = NSS_STATUS_SUCCESS;
 565                   else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
 566                     status = NSS_STATUS_UNAVAIL;
 567                   else
 568                     return result;
 569                 }
 570               else if (line - name == 8)
 571                 {
 572                   if (__strncasecmp (name, "NOTFOUND", 8) == 0)
 573                     status = NSS_STATUS_NOTFOUND;
 574                   else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
 575                     status = NSS_STATUS_TRYAGAIN;
 576                   else
 577                     return result;
 578                 }
 579               else
 580                 return result;
 581
 582               while (isspace (line[0]))
 583                 ++line;
 584               if (line[0] != '=')
 585                 return result;
 586               do
 587                 ++line;
 588               while (isspace (line[0]));
 589
 590               name = line;
 591               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 592                      && line[0] != ']')
 593                 ++line;
 594
 595               if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
 596                 action = NSS_ACTION_RETURN;
 597               else if (line - name == 8
 598                        && __strncasecmp (name, "CONTINUE", 8) == 0)
 599                 action = NSS_ACTION_CONTINUE;
 600               else
 601                 return result;
 602
 603               if (not)
 604                 {
 605                   /* Save the current action setting for this status,
 606                      set them all to the given action, and reset this one.  */
 607                   const lookup_actions save = new_service->actions[2 + status];
 608                   new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
 609                   new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
 610                   new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
 611                   new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
 612                   new_service->actions[2 + status] = save;
 613                 }
 614               else
 615                 new_service->actions[2 + status] = action;
 616
 617               /* Skip white spaces.  */
 618               while (isspace (line[0]))
 619                 ++line;
 620             }
 621           while (line[0] != ']');
 622
 623           /* Skip the ']'.  */
 624           ++line;
 625         }
 626
 627       *nextp = new_service;
 628       nextp = &new_service->next;
 629     }
 630 }
 631
 632 static name_database_entry *
 633 internal_function
 634 nss_getline (char *line)
 635 {
 636   const char *name;
 637   name_database_entry *result;
 638   size_t len;
 639
 640   /* Ignore leading white spaces.  ATTENTION: this is different from
 641      what is implemented in Solaris.  The Solaris man page says a line
 642      beginning with a white space character is ignored.  We regard
 643      this as just another misfeature in Solaris.  */
 644   while (isspace (line[0]))
 645     ++line;
 646
 647   /* Recognize `<database> ":"'.  */
 648   name = line;
 649   while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
 650     ++line;
 651   if (line[0] == '\0' || name == line)
 652     /* Syntax error.  */
 653     return NULL;
 654   *line++ = '\0';
 655
 656   len = strlen (name) + 1;
 657
 658   result = (name_database_entry *) malloc (sizeof (name_database_entry) + len);
 659   if (result == NULL)
 660     return NULL;
 661
 662   /* Save the database name.  */
 663   memcpy (result->name, name, len);
 664
 665   /* Parse the list of services.  */
 666   result->service = nss_parse_service_list (line);
 667
 668   result->next = NULL;
 669   return result;
 670 }
 671
 672
 673 static service_library *
 674 internal_function
 675 nss_new_service (name_database *database, const char *name)
 676 {
 677   service_library **currentp = &database->library;
 678
 679   while (*currentp != NULL)
 680     {
 681       if (strcmp ((*currentp)->name, name) == 0)
 682         return *currentp;
 683       currentp = &(*currentp)->next;
 684     }
 685
 686   /* We have to add the new service.  */
 687   *currentp = (service_library *) malloc (sizeof (service_library));
 688   if (*currentp == NULL)
 689     return NULL;
 690
 691   (*currentp)->name = name;
 692   (*currentp)->lib_handle = NULL;
 693   (*currentp)->next = NULL;
 694
 695   return *currentp;
 696 }
 697
 698
 699 /* Free all resources if necessary.  */
 700 static void __attribute__ ((unused))
 701 free_mem (void)
 702 {
 703   name_database *top = service_table;
 704   name_database_entry *entry;
 705   service_library *library;
 706
 707   if (top == NULL)
 708     /* Maybe we have not read the nsswitch.conf file.  */
 709     return;
 710
 711   /* Don't disturb ongoing other threads (if there are any).  */
 712   service_table = NULL;
 713
 714   entry = top->entry;
 715   while (entry != NULL)
 716     {
 717       name_database_entry *olde = entry;
 718       service_user *service = entry->service;
 719
 720       while (service != NULL)
 721         {
 722           service_user *olds = service;
 723
 724           if (service->known != NULL)
 725             __tdestroy (service->known, free);
 726
 727           service = service->next;
 728           free (olds);
 729         }
 730
 731       entry = entry->next;
 732       free (olde);
 733     }
 734
 735   library = top->library;
 736   while (library != NULL)
 737     {
 738       service_library *oldl = library;
 739
 740       __libc_dlclose (library->lib_handle);
 741
 742       library = library->next;
 743       free (oldl);
 744     }
 745
 746   free (top);
 747 }
 748
 749 text_set_element (__libc_subfreeres, free_mem);