inet/getnetgrent_r.c

   1 /* Copyright (C) 1996-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <assert.h>
  19 #include <atomic.h>
  20 #include <libc-lock.h>
  21 #include <errno.h>
  22 #include <netdb.h>
  23 #include <stdbool.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include "netgroup.h"
  27 #include "nsswitch.h"
  28 #include <sysdep.h>
  29 #include <nscd/nscd_proto.h>
  30
  31
  32 /* Protect above variable against multiple uses at the same time.  */
  33 __libc_lock_define_initialized (static, lock)
  34
  35 /* The whole information for the set/get/endnetgrent functions are
  36    kept in this structure.  */
  37 static struct __netgrent dataset;
  38
  39 /* Set up NIP to run through the services.  Return nonzero if there are no
  40    services (left).  */
  41 static int
  42 setup (void **fctp, service_user **nipp)
  43 {
  44   /* Remember the first service_entry, it's always the same.  */
  45   static bool startp_initialized;
  46   static service_user *startp;
  47   int no_more;
  48
  49   if (!startp_initialized)
  50     {
  51       /* Executing this more than once at the same time must yield the
  52          same result every time.  So we need no locking.  */
  53       no_more = __nss_netgroup_lookup2 (nipp, "setnetgrent", NULL, fctp);
  54       startp = no_more ? (service_user *) -1 : *nipp;
  55 #ifdef PTR_MANGLE
  56       PTR_MANGLE (startp);
  57 #endif
  58       atomic_write_barrier ();
  59       startp_initialized = true;
  60     }
  61   else
  62     {
  63       service_user *nip = startp;
  64 #ifdef PTR_DEMANGLE
  65       PTR_DEMANGLE (nip);
  66 #endif
  67       if (nip == (service_user *) -1)
  68         /* No services at all.  */
  69         return 1;
  70
  71       /* Reset to the beginning of the service list.  */
  72       *nipp = nip;
  73       /* Look up the first function.  */
  74       no_more = __nss_lookup (nipp, "setnetgrent", NULL, fctp);
  75     }
  76   return no_more;
  77 }
  78 \f
  79 /* Free used memory.  */
  80 static void
  81 free_memory (struct __netgrent *data)
  82 {
  83   while (data->known_groups != NULL)
  84     {
  85       struct name_list *tmp = data->known_groups;
  86       data->known_groups = data->known_groups->next;
  87       free (tmp);
  88     }
  89
  90   while (data->needed_groups != NULL)
  91     {
  92       struct name_list *tmp = data->needed_groups;
  93       data->needed_groups = data->needed_groups->next;
  94       free (tmp);
  95     }
  96 }
  97 \f
  98 static void
  99 endnetgrent_hook (struct __netgrent *datap)
 100 {
 101   enum nss_status (*endfct) (struct __netgrent *);
 102
 103   if (datap->nip == NULL || datap->nip == (service_user *) -1l)
 104     return;
 105
 106   endfct = __nss_lookup_function (datap->nip, "endnetgrent");
 107   if (endfct != NULL)
 108     (void) (*endfct) (datap);
 109   datap->nip = NULL;
 110 }
 111
 112 static int
 113 __internal_setnetgrent_reuse (const char *group, struct __netgrent *datap,
 114                               int *errnop)
 115 {
 116   union
 117   {
 118     enum nss_status (*f) (const char *, struct __netgrent *);
 119     void *ptr;
 120   } fct;
 121   enum nss_status status = NSS_STATUS_UNAVAIL;
 122   struct name_list *new_elem;
 123
 124   /* Free data from previous service.  */
 125   endnetgrent_hook (datap);
 126
 127   /* Cycle through all the services and run their setnetgrent functions.  */
 128   int no_more = setup (&fct.ptr, &datap->nip);
 129   while (! no_more)
 130     {
 131       assert (datap->data == NULL);
 132
 133       /* Ignore status, we force check in `__nss_next2'.  */
 134       status = DL_CALL_FCT (*fct.f, (group, datap));
 135
 136       service_user *old_nip = datap->nip;
 137       no_more = __nss_next2 (&datap->nip, "setnetgrent", NULL, &fct.ptr,
 138                              status, 0);
 139
 140       if (status == NSS_STATUS_SUCCESS && ! no_more)
 141         {
 142           enum nss_status (*endfct) (struct __netgrent *);
 143
 144           endfct = __nss_lookup_function (old_nip, "endnetgrent");
 145           if (endfct != NULL)
 146             (void) DL_CALL_FCT (*endfct, (datap));
 147         }
 148     }
 149
 150   /* Add the current group to the list of known groups.  */
 151   size_t group_len = strlen (group) + 1;
 152   new_elem = (struct name_list *) malloc (sizeof (struct name_list)
 153                                           + group_len);
 154   if (new_elem == NULL)
 155     {
 156       *errnop = errno;
 157       status = NSS_STATUS_TRYAGAIN;
 158     }
 159   else
 160     {
 161       new_elem->next = datap->known_groups;
 162       memcpy (new_elem->name, group, group_len);
 163       datap->known_groups = new_elem;
 164     }
 165
 166   return status == NSS_STATUS_SUCCESS;
 167 }
 168
 169 int
 170 __internal_setnetgrent (const char *group, struct __netgrent *datap)
 171 {
 172   /* Free list of all netgroup names from last run.  */
 173   free_memory (datap);
 174
 175   return __internal_setnetgrent_reuse (group, datap, &errno);
 176 }
 177 libc_hidden_def (__internal_setnetgrent)
 178
 179 static int
 180 nscd_setnetgrent (const char *group)
 181 {
 182 #ifdef USE_NSCD
 183   if (__nss_not_use_nscd_netgroup > 0
 184       && ++__nss_not_use_nscd_netgroup > NSS_NSCD_RETRY)
 185     __nss_not_use_nscd_netgroup = 0;
 186
 187   if (!__nss_not_use_nscd_netgroup
 188       && !__nss_database_custom[NSS_DBSIDX_netgroup])
 189     return __nscd_setnetgrent (group, &dataset);
 190 #endif
 191   return -1;
 192 }
 193
 194 int
 195 setnetgrent (const char *group)
 196 {
 197   int result;
 198
 199   __libc_lock_lock (lock);
 200
 201   result = nscd_setnetgrent (group);
 202   if (result < 0)
 203     result = __internal_setnetgrent (group, &dataset);
 204
 205   __libc_lock_unlock (lock);
 206
 207   return result;
 208 }
 209
 210 void
 211 __internal_endnetgrent (struct __netgrent *datap)
 212 {
 213   endnetgrent_hook (datap);
 214   /* Now free list of all netgroup names from last run.  */
 215   free_memory (datap);
 216 }
 217 libc_hidden_def (__internal_endnetgrent)
 218
 219
 220 void
 221 endnetgrent (void)
 222 {
 223   __libc_lock_lock (lock);
 224
 225   __internal_endnetgrent (&dataset);
 226
 227   __libc_lock_unlock (lock);
 228 }
 229
 230 #ifdef USE_NSCD
 231 static const char *
 232 get_nonempty_val (const char *in)
 233 {
 234   if (*in == '\0')
 235     return NULL;
 236   return in;
 237 }
 238
 239 static enum nss_status
 240 nscd_getnetgrent (struct __netgrent *datap, char *buffer, size_t buflen,
 241                   int *errnop)
 242 {
 243   if (datap->cursor >= datap->data + datap->data_size)
 244     return NSS_STATUS_UNAVAIL;
 245
 246   datap->type = triple_val;
 247   datap->val.triple.host = get_nonempty_val (datap->cursor);
 248   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
 249   datap->val.triple.user = get_nonempty_val (datap->cursor);
 250   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
 251   datap->val.triple.domain = get_nonempty_val (datap->cursor);
 252   datap->cursor = (char *) __rawmemchr (datap->cursor, '\0') + 1;
 253
 254   return NSS_STATUS_SUCCESS;
 255 }
 256 #endif
 257
 258 int
 259 __internal_getnetgrent_r (char **hostp, char **userp, char **domainp,
 260                           struct __netgrent *datap,
 261                           char *buffer, size_t buflen, int *errnop)
 262 {
 263   enum nss_status (*fct) (struct __netgrent *, char *, size_t, int *);
 264
 265   /* Initialize status to return if no more functions are found.  */
 266   enum nss_status status = NSS_STATUS_NOTFOUND;
 267
 268   /* Run through available functions, starting with the same function last
 269      run.  We will repeat each function as long as it succeeds, and then go
 270      on to the next service action.  */
 271   int no_more = datap->nip == NULL;
 272   if (! no_more)
 273     {
 274 #ifdef USE_NSCD
 275       /* This bogus function pointer is a special marker left by
 276          __nscd_setnetgrent to tell us to use the data it left
 277          before considering any modules.  */
 278       if (datap->nip == (service_user *) -1l)
 279         fct = nscd_getnetgrent;
 280       else
 281 #endif
 282         {
 283           fct = __nss_lookup_function (datap->nip, "getnetgrent_r");
 284           no_more = fct == NULL;
 285         }
 286
 287       while (! no_more)
 288         {
 289           status = DL_CALL_FCT (*fct, (datap, buffer, buflen, &errno));
 290
 291           if (status == NSS_STATUS_RETURN
 292               /* The service returned a NOTFOUND, but there are more groups that
 293                  we need to resolve before we give up.  */
 294               || (status == NSS_STATUS_NOTFOUND && datap->needed_groups != NULL))
 295             {
 296               /* This was the last one for this group.  Look at next group
 297                  if available.  */
 298               int found = 0;
 299               while (datap->needed_groups != NULL && ! found)
 300                 {
 301                   struct name_list *tmp = datap->needed_groups;
 302                   datap->needed_groups = datap->needed_groups->next;
 303                   tmp->next = datap->known_groups;
 304                   datap->known_groups = tmp;
 305
 306                   found = __internal_setnetgrent_reuse (datap->known_groups->name,
 307                                                         datap, errnop);
 308                 }
 309
 310               if (found && datap->nip != NULL)
 311                 {
 312                   fct = __nss_lookup_function (datap->nip, "getnetgrent_r");
 313                   if (fct != NULL)
 314                     continue;
 315                 }
 316             }
 317           else if (status == NSS_STATUS_SUCCESS && datap->type == group_val)
 318             {
 319               /* The last entry was a name of another netgroup.  */
 320               struct name_list *namep;
 321
 322               /* Ignore if we've seen the name before.  */
 323               for (namep = datap->known_groups; namep != NULL;
 324                    namep = namep->next)
 325                 if (strcmp (datap->val.group, namep->name) == 0)
 326                   break;
 327               if (namep == NULL)
 328                 for (namep = datap->needed_groups; namep != NULL;
 329                      namep = namep->next)
 330                   if (strcmp (datap->val.group, namep->name) == 0)
 331                     break;
 332               if (namep != NULL)
 333                 /* Really ignore.  */
 334                 continue;
 335
 336               size_t group_len = strlen (datap->val.group) + 1;
 337               namep = (struct name_list *) malloc (sizeof (struct name_list)
 338                                                   + group_len);
 339               if (namep == NULL)
 340                 /* We are out of memory.  */
 341                 status = NSS_STATUS_RETURN;
 342               else
 343                 {
 344                   namep->next = datap->needed_groups;
 345                   memcpy (namep->name, datap->val.group, group_len);
 346                   datap->needed_groups = namep;
 347                   /* And get the next entry.  */
 348                   continue;
 349                 }
 350             }
 351           break;
 352         }
 353     }
 354
 355   if (status == NSS_STATUS_SUCCESS)
 356     {
 357       *hostp = (char *) datap->val.triple.host;
 358       *userp = (char *) datap->val.triple.user;
 359       *domainp = (char *) datap->val.triple.domain;
 360     }
 361
 362   return status == NSS_STATUS_SUCCESS ? 1 : 0;
 363 }
 364 libc_hidden_def (__internal_getnetgrent_r)
 365
 366 /* The real entry point.  */
 367 int
 368 __getnetgrent_r (char **hostp, char **userp, char **domainp,
 369                  char *buffer, size_t buflen)
 370 {
 371   enum nss_status status;
 372
 373   __libc_lock_lock (lock);
 374
 375   status = __internal_getnetgrent_r (hostp, userp, domainp, &dataset,
 376                                      buffer, buflen, &errno);
 377
 378   __libc_lock_unlock (lock);
 379
 380   return status;
 381 }
 382 weak_alias (__getnetgrent_r, getnetgrent_r)
 383 \f
 384 /* Test whether given (host,user,domain) triple is in NETGROUP.  */
 385 int
 386 innetgr (const char *netgroup, const char *host, const char *user,
 387          const char *domain)
 388 {
 389 #ifdef USE_NSCD
 390   if (__nss_not_use_nscd_netgroup > 0
 391       && ++__nss_not_use_nscd_netgroup > NSS_NSCD_RETRY)
 392     __nss_not_use_nscd_netgroup = 0;
 393
 394   if (!__nss_not_use_nscd_netgroup
 395       && !__nss_database_custom[NSS_DBSIDX_netgroup])
 396     {
 397       int result = __nscd_innetgr (netgroup, host, user, domain);
 398       if (result >= 0)
 399         return result;
 400     }
 401 #endif
 402
 403   union
 404   {
 405     enum nss_status (*f) (const char *, struct __netgrent *);
 406     void *ptr;
 407   } setfct;
 408   void (*endfct) (struct __netgrent *);
 409   int (*getfct) (struct __netgrent *, char *, size_t, int *);
 410   struct __netgrent entry;
 411   int result = 0;
 412   const char *current_group = netgroup;
 413
 414   memset (&entry, '\0', sizeof (entry));
 415
 416   /* Walk through the services until we found an answer or we shall
 417      not work further.  We can do some optimization here.  Since all
 418      services must provide the `setnetgrent' function we can do all
 419      the work during one walk through the service list.  */
 420   while (1)
 421     {
 422       int no_more = setup (&setfct.ptr, &entry.nip);
 423       while (! no_more)
 424         {
 425           assert (entry.data == NULL);
 426
 427           /* Open netgroup.  */
 428           enum nss_status status = DL_CALL_FCT (*setfct.f,
 429                                                 (current_group, &entry));
 430
 431           if (status == NSS_STATUS_SUCCESS
 432               && (getfct = __nss_lookup_function (entry.nip, "getnetgrent_r"))
 433                  != NULL)
 434             {
 435               char buffer[1024];
 436
 437               while (DL_CALL_FCT (*getfct,
 438                                   (&entry, buffer, sizeof buffer, &errno))
 439                      == NSS_STATUS_SUCCESS)
 440                 {
 441                   if (entry.type == group_val)
 442                     {
 443                       /* Make sure we haven't seen the name before.  */
 444                       struct name_list *namep;
 445
 446                       for (namep = entry.known_groups; namep != NULL;
 447                            namep = namep->next)
 448                         if (strcmp (entry.val.group, namep->name) == 0)
 449                           break;
 450                       if (namep == NULL)
 451                         for (namep = entry.needed_groups; namep != NULL;
 452                              namep = namep->next)
 453                           if (strcmp (entry.val.group, namep->name) == 0)
 454                             break;
 455                       if (namep == NULL
 456                           && strcmp (netgroup, entry.val.group) != 0)
 457                         {
 458                           size_t group_len = strlen (entry.val.group) + 1;
 459                           namep =
 460                             (struct name_list *) malloc (sizeof (*namep)
 461                                                          + group_len);
 462                           if (namep == NULL)
 463                             {
 464                               /* Out of memory, simply return.  */
 465                               result = -1;
 466                               break;
 467                             }
 468
 469                           namep->next = entry.needed_groups;
 470                           memcpy (namep->name, entry.val.group, group_len);
 471                           entry.needed_groups = namep;
 472                         }
 473                     }
 474                   else
 475                     {
 476                       if ((entry.val.triple.host == NULL || host == NULL
 477                            || __strcasecmp (entry.val.triple.host, host) == 0)
 478                           && (entry.val.triple.user == NULL || user == NULL
 479                               || strcmp (entry.val.triple.user, user) == 0)
 480                           && (entry.val.triple.domain == NULL || domain == NULL
 481                               || __strcasecmp (entry.val.triple.domain,
 482                                                domain) == 0))
 483                         {
 484                           result = 1;
 485                           break;
 486                         }
 487                     }
 488                 }
 489
 490               /* If we found one service which does know the given
 491                  netgroup we don't try further.  */
 492               status = NSS_STATUS_RETURN;
 493             }
 494
 495           /* Free all resources of the service.  */
 496           endfct = __nss_lookup_function (entry.nip, "endnetgrent");
 497           if (endfct != NULL)
 498             DL_CALL_FCT (*endfct, (&entry));
 499
 500           if (result != 0)
 501             break;
 502
 503           /* Look for the next service.  */
 504           no_more = __nss_next2 (&entry.nip, "setnetgrent", NULL,
 505                                  &setfct.ptr, status, 0);
 506         }
 507
 508       if (result == 0 && entry.needed_groups != NULL)
 509         {
 510           struct name_list *tmp = entry.needed_groups;
 511           entry.needed_groups = tmp->next;
 512           tmp->next = entry.known_groups;
 513           entry.known_groups = tmp;
 514           current_group = tmp->name;
 515           continue;
 516         }
 517
 518       /* No way out.  */
 519       break;
 520     }
 521
 522   /* Free the memory.  */
 523   free_memory (&entry);
 524
 525   return result == 1;
 526 }
 527 libc_hidden_def (innetgr)