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