nss/nsswitch.c

   1 /* Copyright (C) 1996,1997,1998,1999,2001 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;                               \
  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
 140
 141 /* -1 == not found
 142     0 == function found
 143     1 == finished */
 144 int
 145 __nss_lookup (service_user **ni, const char *fct_name, void **fctp)
 146 {
 147   *fctp = __nss_lookup_function (*ni, fct_name);
 148
 149   while (*fctp == NULL
 150          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 151          && (*ni)->next != NULL)
 152     {
 153       *ni = (*ni)->next;
 154
 155       *fctp = __nss_lookup_function (*ni, fct_name);
 156     }
 157
 158   return *fctp != NULL ? 0 : (*ni)->next == NULL ? 1 : -1;
 159 }
 160
 161
 162 /* -1 == not found
 163     0 == adjusted for next function
 164     1 == finished */
 165 int
 166 __nss_next (service_user **ni, const char *fct_name, void **fctp, int status,
 167             int all_values)
 168 {
 169   if (all_values)
 170     {
 171       if (nss_next_action (*ni, NSS_STATUS_TRYAGAIN) == NSS_ACTION_RETURN
 172           && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_RETURN
 173           && nss_next_action (*ni, NSS_STATUS_NOTFOUND) == NSS_ACTION_RETURN
 174           && nss_next_action (*ni, NSS_STATUS_SUCCESS) == NSS_ACTION_RETURN)
 175         return 1;
 176     }
 177   else
 178     {
 179       /* This is really only for debugging.  */
 180        if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 181          __libc_fatal ("illegal status in __nss_next");
 182
 183        if (nss_next_action (*ni, status) == NSS_ACTION_RETURN)
 184          return 1;
 185     }
 186
 187   if ((*ni)->next == NULL)
 188     return -1;
 189
 190   do
 191     {
 192       *ni = (*ni)->next;
 193
 194       *fctp = __nss_lookup_function (*ni, fct_name);
 195     }
 196   while (*fctp == NULL
 197          && nss_next_action (*ni, NSS_STATUS_UNAVAIL) == NSS_ACTION_CONTINUE
 198          && (*ni)->next != NULL);
 199
 200   return *fctp != NULL ? 0 : -1;
 201 }
 202
 203
 204 int
 205 __nss_configure_lookup (const char *dbname, const char *service_line)
 206 {
 207   service_user *new_db;
 208   size_t cnt;
 209
 210   for (cnt = 0; cnt < sizeof databases; ++cnt)
 211     {
 212       int cmp = strcmp (dbname, databases[cnt].name);
 213       if (cmp == 0)
 214         break;
 215       if (cmp < 0)
 216         {
 217           __set_errno (EINVAL);
 218           return -1;
 219         }
 220     }
 221
 222   if (cnt == sizeof databases)
 223     {
 224       __set_errno (EINVAL);
 225       return -1;
 226     }
 227
 228   /* Test whether it is really used.  */
 229   if (databases[cnt].dbp == NULL)
 230     /* Nothing to do, but we could do.  */
 231     return 0;
 232
 233   /* Try to generate new data.  */
 234   new_db = nss_parse_service_list (service_line);
 235   if (new_db == NULL)
 236     {
 237       /* Illegal service specification.  */
 238       __set_errno (EINVAL);
 239       return -1;
 240     }
 241
 242   /* Prevent multiple threads to change the service table.  */
 243   __libc_lock_lock (lock);
 244
 245   /* Install new rules.  */
 246   *databases[cnt].dbp = new_db;
 247
 248   __libc_lock_unlock (lock);
 249
 250   return 0;
 251 }
 252
 253
 254 /* Comparison function for searching NI->known tree.  */
 255 static int
 256 known_compare (const void *p1, const void *p2)
 257 {
 258   return p1 == p2 ? 0 : strcmp (*(const char *const *) p1,
 259                                 *(const char *const *) p2);
 260 }
 261
 262
 263 void *
 264 __nss_lookup_function (service_user *ni, const char *fct_name)
 265 {
 266   void **found, *result;
 267
 268   /* We now modify global data.  Protect it.  */
 269   __libc_lock_lock (lock);
 270
 271   /* Search the tree of functions previously requested.  Data in the
 272      tree are `known_function' structures, whose first member is a
 273      `const char *', the lookup key.  The search returns a pointer to
 274      the tree node structure; the first member of the is a pointer to
 275      our structure (i.e. what will be a `known_function'); since the
 276      first member of that is the lookup key string, &FCT_NAME is close
 277      enough to a pointer to our structure to use as a lookup key that
 278      will be passed to `known_compare' (above).  */
 279
 280   found = __tsearch (&fct_name, (void **) &ni->known, &known_compare);
 281   if (*found != &fct_name)
 282     /* The search found an existing structure in the tree.  */
 283     result = ((known_function *) *found)->fct_ptr;
 284   else
 285     {
 286       /* This name was not known before.  Now we have a node in the tree
 287          (in the proper sorted position for FCT_NAME) that points to
 288          &FCT_NAME instead of any real `known_function' structure.
 289          Allocate a new structure and fill it in.  */
 290
 291       known_function *known = malloc (sizeof *known);
 292       if (! known)
 293         {
 294         remove_from_tree:
 295           /* Oops.  We can't instantiate this node properly.
 296              Remove it from the tree.  */
 297           __tdelete (&fct_name, (void **) &ni->known, &known_compare);
 298           result = NULL;
 299         }
 300       else
 301         {
 302           /* Point the tree node at this new structure.  */
 303           *found = known;
 304           known->fct_name = fct_name;
 305
 306           if (ni->library == NULL)
 307             {
 308               /* This service has not yet been used.  Fetch the service
 309                  library for it, creating a new one if need be.  If there
 310                  is no service table from the file, this static variable
 311                  holds the head of the service_library list made from the
 312                  default configuration.  */
 313               static name_database default_table;
 314               ni->library = nss_new_service (service_table ?: &default_table,
 315                                              ni->name);
 316               if (ni->library == NULL)
 317                 {
 318                   /* This only happens when out of memory.  */
 319                   free (known);
 320                   goto remove_from_tree;
 321                 }
 322             }
 323
 324 #if !defined DO_STATIC_NSS || defined SHARED
 325           if (ni->library->lib_handle == NULL)
 326             {
 327               /* Load the shared library.  */
 328               size_t shlen = (7 + strlen (ni->library->name) + 3
 329                               + strlen (__nss_shlib_revision) + 1);
 330               int saved_errno = errno;
 331               char shlib_name[shlen];
 332
 333               /* Construct shared object name.  */
 334               __stpcpy (__stpcpy (__stpcpy (__stpcpy (shlib_name,
 335                                                       "libnss_"),
 336                                             ni->library->name),
 337                                   ".so"),
 338                         __nss_shlib_revision);
 339
 340               ni->library->lib_handle = __libc_dlopen (shlib_name);
 341               if (ni->library->lib_handle == NULL)
 342                 {
 343                   /* Failed to load the library.  */
 344                   ni->library->lib_handle = (void *) -1l;
 345                   __set_errno (saved_errno);
 346                 }
 347             }
 348
 349           if (ni->library->lib_handle == (void *) -1l)
 350             /* Library not found => function not found.  */
 351             result = NULL;
 352           else
 353             {
 354               /* Get the desired function.  */
 355               size_t namlen = (5 + strlen (ni->library->name) + 1
 356                                + strlen (fct_name) + 1);
 357               char name[namlen];
 358
 359               /* Construct the function name.  */
 360               __stpcpy (__stpcpy (__stpcpy (__stpcpy (name, "_nss_"),
 361                                             ni->library->name),
 362                                   "_"),
 363                         fct_name);
 364
 365               /* Look up the symbol.  */
 366               result = __libc_dlsym (ni->library->lib_handle, name);
 367             }
 368 #else
 369           /* We can't get function address dynamically in static linking. */
 370           {
 371 # define DEFINE_ENT(h,nm)                                                     \
 372             { #h"_get"#nm"ent_r", _nss_##h##_get##nm##ent_r },                \
 373             { #h"_end"#nm"ent", _nss_##h##_end##nm##ent },                    \
 374             { #h"_set"#nm"ent", _nss_##h##_set##nm##ent },
 375 # define DEFINE_GET(h,nm)                                                     \
 376             { #h"_get"#nm"_r", _nss_##h##_get##nm##_r },
 377 # define DEFINE_GETBY(h,nm,ky)                                                \
 378             { #h"_get"#nm"by"#ky"_r", _nss_##h##_get##nm##by##ky##_r },
 379             static struct fct_tbl { const char *fname; void *fp; } *tp, tbl[] =
 380               {
 381 # include "function.def"
 382                 { NULL, NULL }
 383               };
 384             size_t namlen = (5 + strlen (ni->library->name) + 1
 385                              + strlen (fct_name) + 1);
 386             char name[namlen];
 387
 388             /* Construct the function name.  */
 389             __stpcpy (__stpcpy (__stpcpy (name, ni->library->name),
 390                                 "_"),
 391                       fct_name);
 392
 393             result = NULL;
 394             for (tp = &tbl[0]; tp->fname; tp++)
 395               if (strcmp (tp->fname, name) == 0)
 396                 {
 397                   result = tp->fp;
 398                   break;
 399                 }
 400           }
 401 #endif
 402
 403           /* Remember function pointer for later calls.  Even if null, we
 404              record it so a second try needn't search the library again.  */
 405           known->fct_ptr = result;
 406         }
 407     }
 408
 409   /* Remove the lock.  */
 410   __libc_lock_unlock (lock);
 411
 412   return result;
 413 }
 414
 415
 416 static name_database *
 417 internal_function
 418 nss_parse_file (const char *fname)
 419 {
 420   FILE *fp;
 421   name_database *result;
 422   name_database_entry *last;
 423   char *line;
 424   size_t len;
 425
 426   /* Open the configuration file.  */
 427   fp = fopen (fname, "r");
 428   if (fp == NULL)
 429     return NULL;
 430
 431   /* No threads use this stream.  */
 432   __fsetlocking (fp, FSETLOCKING_BYCALLER);
 433
 434   result = (name_database *) malloc (sizeof (name_database));
 435   if (result == NULL)
 436     return NULL;
 437
 438   result->entry = NULL;
 439   result->library = NULL;
 440   last = NULL;
 441   line = NULL;
 442   len = 0;
 443   do
 444     {
 445       name_database_entry *this;
 446       ssize_t n;
 447
 448       n = __getline (&line, &len, fp);
 449       if (n < 0)
 450         break;
 451       if (line[n - 1] == '\n')
 452         line[n - 1] = '\0';
 453
 454       /* Because the file format does not know any form of quoting we
 455          can search forward for the next '#' character and if found
 456          make it terminating the line.  */
 457       *__strchrnul (line, '#') = '\0';
 458
 459       /* If the line is blank it is ignored.  */
 460       if (line[0] == '\0')
 461         continue;
 462
 463       /* Each line completely specifies the actions for a database.  */
 464       this = nss_getline (line);
 465       if (this != NULL)
 466         {
 467           if (last != NULL)
 468             last->next = this;
 469           else
 470             result->entry = this;
 471
 472           last = this;
 473         }
 474     }
 475   while (!feof_unlocked (fp));
 476
 477   /* Free the buffer.  */
 478   free (line);
 479   /* Close configuration file.  */
 480   fclose (fp);
 481
 482   return result;
 483 }
 484
 485
 486 /* Read the source names:
 487         `( <source> ( "[" "!"? (<status> "=" <action> )+ "]" )? )*'
 488    */
 489 static service_user *
 490 internal_function
 491 nss_parse_service_list (const char *line)
 492 {
 493   service_user *result = NULL, **nextp = &result;
 494
 495   while (1)
 496     {
 497       service_user *new_service;
 498       const char *name;
 499
 500       while (isspace (line[0]))
 501         ++line;
 502       if (line[0] == '\0')
 503         /* No source specified.  */
 504         return result;
 505
 506       /* Read <source> identifier.  */
 507       name = line;
 508       while (line[0] != '\0' && !isspace (line[0]) && line[0] != '[')
 509         ++line;
 510       if (name == line)
 511         return result;
 512
 513
 514       new_service = (service_user *) malloc (sizeof (service_user)
 515                                              + (line - name + 1));
 516       if (new_service == NULL)
 517         return result;
 518
 519       *((char *) __mempcpy (new_service->name, name, line - name)) = '\0';
 520
 521       /* Set default actions.  */
 522       new_service->actions[2 + NSS_STATUS_TRYAGAIN] = NSS_ACTION_CONTINUE;
 523       new_service->actions[2 + NSS_STATUS_UNAVAIL] = NSS_ACTION_CONTINUE;
 524       new_service->actions[2 + NSS_STATUS_NOTFOUND] = NSS_ACTION_CONTINUE;
 525       new_service->actions[2 + NSS_STATUS_SUCCESS] = NSS_ACTION_RETURN;
 526       new_service->actions[2 + NSS_STATUS_RETURN] = NSS_ACTION_RETURN;
 527       new_service->library = NULL;
 528       new_service->known = NULL;
 529       new_service->next = NULL;
 530
 531       while (isspace (line[0]))
 532         ++line;
 533
 534       if (line[0] == '[')
 535         {
 536           /* Read criterions.  */
 537           do
 538             ++line;
 539           while (line[0] != '\0' && isspace (line[0]));
 540
 541           do
 542             {
 543               int not;
 544               enum nss_status status;
 545               lookup_actions action;
 546
 547               /* Grok ! before name to mean all statii but that one.  */
 548               not = line[0] == '!';
 549               if (not)
 550                 ++line;
 551
 552               /* Read status name.  */
 553               name = line;
 554               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 555                      && line[0] != ']')
 556                 ++line;
 557
 558               /* Compare with known statii.  */
 559               if (line - name == 7)
 560                 {
 561                   if (__strncasecmp (name, "SUCCESS", 7) == 0)
 562                     status = NSS_STATUS_SUCCESS;
 563                   else if (__strncasecmp (name, "UNAVAIL", 7) == 0)
 564                     status = NSS_STATUS_UNAVAIL;
 565                   else
 566                     return result;
 567                 }
 568               else if (line - name == 8)
 569                 {
 570                   if (__strncasecmp (name, "NOTFOUND", 8) == 0)
 571                     status = NSS_STATUS_NOTFOUND;
 572                   else if (__strncasecmp (name, "TRYAGAIN", 8) == 0)
 573                     status = NSS_STATUS_TRYAGAIN;
 574                   else
 575                     return result;
 576                 }
 577               else
 578                 return result;
 579
 580               while (isspace (line[0]))
 581                 ++line;
 582               if (line[0] != '=')
 583                 return result;
 584               do
 585                 ++line;
 586               while (isspace (line[0]));
 587
 588               name = line;
 589               while (line[0] != '\0' && !isspace (line[0]) && line[0] != '='
 590                      && line[0] != ']')
 591                 ++line;
 592
 593               if (line - name == 6 && __strncasecmp (name, "RETURN", 6) == 0)
 594                 action = NSS_ACTION_RETURN;
 595               else if (line - name == 8
 596                        && __strncasecmp (name, "CONTINUE", 8) == 0)
 597                 action = NSS_ACTION_CONTINUE;
 598               else
 599                 return result;
 600
 601               if (not)
 602                 {
 603                   /* Save the current action setting for this status,
 604                      set them all to the given action, and reset this one.  */
 605                   const lookup_actions save = new_service->actions[2 + status];
 606                   new_service->actions[2 + NSS_STATUS_TRYAGAIN] = action;
 607                   new_service->actions[2 + NSS_STATUS_UNAVAIL] = action;
 608                   new_service->actions[2 + NSS_STATUS_NOTFOUND] = action;
 609                   new_service->actions[2 + NSS_STATUS_SUCCESS] = action;
 610                   new_service->actions[2 + status] = save;
 611                 }
 612               else
 613                 new_service->actions[2 + status] = action;
 614
 615               /* Skip white spaces.  */
 616               while (isspace (line[0]))
 617                 ++line;
 618             }
 619           while (line[0] != ']');
 620
 621           /* Skip the ']'.  */
 622           ++line;
 623         }
 624
 625       *nextp = new_service;
 626       nextp = &new_service->next;
 627     }
 628 }
 629
 630 static name_database_entry *
 631 internal_function
 632 nss_getline (char *line)
 633 {
 634   const char *name;
 635   name_database_entry *result;
 636   size_t len;
 637
 638   /* Ignore leading white spaces.  ATTENTION: this is different from
 639      what is implemented in Solaris.  The Solaris man page says a line
 640      beginning with a white space character is ignored.  We regard
 641      this as just another misfeature in Solaris.  */
 642   while (isspace (line[0]))
 643     ++line;
 644
 645   /* Recognize `<database> ":"'.  */
 646   name = line;
 647   while (line[0] != '\0' && !isspace (line[0]) && line[0] != ':')
 648     ++line;
 649   if (line[0] == '\0' || name == line)
 650     /* Syntax error.  */
 651     return NULL;
 652   *line++ = '\0';
 653
 654   len = strlen (name) + 1;
 655
 656   result = (name_database_entry *) malloc (sizeof (name_database_entry) + len);
 657   if (result == NULL)
 658     return NULL;
 659
 660   /* Save the database name.  */
 661   memcpy (result->name, name, len);
 662
 663   /* Parse the list of services.  */
 664   result->service = nss_parse_service_list (line);
 665
 666   result->next = NULL;
 667   return result;
 668 }
 669
 670
 671 static service_library *
 672 internal_function
 673 nss_new_service (name_database *database, const char *name)
 674 {
 675   service_library **currentp = &database->library;
 676
 677   while (*currentp != NULL)
 678     {
 679       if (strcmp ((*currentp)->name, name) == 0)
 680         return *currentp;
 681       currentp = &(*currentp)->next;
 682     }
 683
 684   /* We have to add the new service.  */
 685   *currentp = (service_library *) malloc (sizeof (service_library));
 686   if (*currentp == NULL)
 687     return NULL;
 688
 689   (*currentp)->name = name;
 690   (*currentp)->lib_handle = NULL;
 691   (*currentp)->next = NULL;
 692
 693   return *currentp;
 694 }
 695
 696
 697 /* Free all resources if necessary.  */
 698 static void __attribute__ ((unused))
 699 free_mem (void)
 700 {
 701   name_database *top = service_table;
 702   name_database_entry *entry;
 703   service_library *library;
 704
 705   if (top == NULL)
 706     /* Maybe we have not read the nsswitch.conf file.  */
 707     return;
 708
 709   /* Don't disturb ongoing other threads (if there are any).  */
 710   service_table = NULL;
 711
 712   entry = top->entry;
 713   while (entry != NULL)
 714     {
 715       name_database_entry *olde = entry;
 716       service_user *service = entry->service;
 717
 718       while (service != NULL)
 719         {
 720           service_user *olds = service;
 721
 722           if (service->known != NULL)
 723             __tdestroy (service->known, free);
 724
 725           service = service->next;
 726           free (olds);
 727         }
 728
 729       entry = entry->next;
 730       free (olde);
 731     }
 732
 733   library = top->library;
 734   while (library != NULL)
 735     {
 736       service_library *oldl = library;
 737
 738       __libc_dlclose (library->lib_handle);
 739
 740       library = library->next;
 741       free (oldl);
 742     }
 743
 744   free (top);
 745 }
 746
 747 text_set_element (__libc_subfreeres, free_mem);