nscd/netgroupcache.c

   1 /* Cache handling for netgroup lookup.
   2    Copyright (C) 2011-2025 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published
   7    by the Free Software Foundation; version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <alloca.h>
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <libintl.h>
  22 #include <stdbool.h>
  23 #include <stdlib.h>
  24 #include <unistd.h>
  25 #include <sys/mman.h>
  26 #include <scratch_buffer.h>
  27
  28 #include "../nss/netgroup.h"
  29 #include "nscd.h"
  30 #include "dbg_log.h"
  31
  32 #include <kernel-features.h>
  33
  34
  35 /* This is the standard reply in case the service is disabled.  */
  36 static const netgroup_response_header disabled =
  37 {
  38   .version = NSCD_VERSION,
  39   .found = -1,
  40   .nresults = 0,
  41   .result_len = 0
  42 };
  43
  44 /* This is the struct describing how to write this record.  */
  45 const struct iovec netgroup_iov_disabled =
  46 {
  47   .iov_base = (void *) &disabled,
  48   .iov_len = sizeof (disabled)
  49 };
  50
  51
  52 /* This is the standard reply in case we haven't found the dataset.  */
  53 static const netgroup_response_header notfound =
  54 {
  55   .version = NSCD_VERSION,
  56   .found = 0,
  57   .nresults = 0,
  58   .result_len = 0
  59 };
  60
  61
  62 struct dataset
  63 {
  64   struct datahead head;
  65   netgroup_response_header resp;
  66   char strdata[0];
  67 };
  68
  69 /* Send a notfound response to FD.  Always returns -1 to indicate an
  70    ephemeral error.  */
  71 static time_t
  72 send_notfound (int fd)
  73 {
  74   if (fd != -1)
  75     TEMP_FAILURE_RETRY (send (fd, &notfound, sizeof (notfound), MSG_NOSIGNAL));
  76   return -1;
  77 }
  78
  79 /* Sends a notfound message and prepares a notfound dataset to write to the
  80    cache.  Returns true if there was enough memory to allocate the dataset and
  81    returns the dataset in DATASETP, total bytes to write in TOTALP and the
  82    timeout in TIMEOUTP.  KEY_COPY is set to point to the copy of the key in the
  83    dataset. */
  84 static bool
  85 do_notfound (struct database_dyn *db, int fd, request_header *req,
  86                const char *key, struct dataset **datasetp, ssize_t *totalp,
  87                time_t *timeoutp, char **key_copy)
  88 {
  89   struct dataset *dataset;
  90   ssize_t total;
  91   time_t timeout;
  92   bool cacheable = false;
  93
  94   total = sizeof (notfound);
  95   timeout = time (NULL) + db->negtimeout;
  96
  97   send_notfound (fd);
  98
  99   dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1);
 100   /* If we cannot permanently store the result, so be it.  */
 101   if (dataset != NULL)
 102     {
 103       timeout = datahead_init_neg (&dataset->head,
 104                                    sizeof (struct dataset) + req->key_len,
 105                                    total, db->negtimeout);
 106
 107       /* This is the reply.  */
 108       memcpy (&dataset->resp, &notfound, total);
 109
 110       /* Copy the key data.  */
 111       memcpy (dataset->strdata, key, req->key_len);
 112       *key_copy = dataset->strdata;
 113
 114       cacheable = true;
 115     }
 116   *timeoutp = timeout;
 117   *totalp = total;
 118   *datasetp = dataset;
 119   return cacheable;
 120 }
 121
 122 struct addgetnetgrentX_scratch
 123 {
 124   /* This is the result that the caller should use.  It can be NULL,
 125      point into buffer, or it can be in the cache.  */
 126   struct dataset *dataset;
 127
 128   struct scratch_buffer buffer;
 129
 130   /* Used internally in addgetnetgrentX as a staging area.  */
 131   struct scratch_buffer tmp;
 132
 133   /* Number of bytes in buffer that are actually used.  */
 134   size_t buffer_used;
 135 };
 136
 137 static void
 138 addgetnetgrentX_scratch_init (struct addgetnetgrentX_scratch *scratch)
 139 {
 140   scratch->dataset = NULL;
 141   scratch_buffer_init (&scratch->buffer);
 142   scratch_buffer_init (&scratch->tmp);
 143
 144   /* Reserve space for the header.  */
 145   scratch->buffer_used = sizeof (struct dataset);
 146   static_assert (sizeof (struct dataset) < sizeof (scratch->tmp.__space),
 147                  "initial buffer space");
 148   memset (scratch->tmp.data, 0, sizeof (struct dataset));
 149 }
 150
 151 static void
 152 addgetnetgrentX_scratch_free (struct addgetnetgrentX_scratch *scratch)
 153 {
 154   scratch_buffer_free (&scratch->buffer);
 155   scratch_buffer_free (&scratch->tmp);
 156 }
 157
 158 /* Copy LENGTH bytes from S into SCRATCH.  Returns NULL if SCRATCH
 159    could not be resized, otherwise a pointer to the copy.  */
 160 static char *
 161 addgetnetgrentX_append_n (struct addgetnetgrentX_scratch *scratch,
 162                           const char *s, size_t length)
 163 {
 164   while (true)
 165     {
 166       size_t remaining = scratch->buffer.length - scratch->buffer_used;
 167       if (remaining >= length)
 168         break;
 169       if (!scratch_buffer_grow_preserve (&scratch->buffer))
 170         return NULL;
 171     }
 172   char *copy = scratch->buffer.data + scratch->buffer_used;
 173   memcpy (copy, s, length);
 174   scratch->buffer_used += length;
 175   return copy;
 176 }
 177
 178 /* Copy S into SCRATCH, including its null terminator.  Returns false
 179    if SCRATCH could not be resized.  */
 180 static bool
 181 addgetnetgrentX_append (struct addgetnetgrentX_scratch *scratch, const char *s)
 182 {
 183   if (s == NULL)
 184     s = "";
 185   return addgetnetgrentX_append_n (scratch, s, strlen (s) + 1) != NULL;
 186 }
 187
 188 /* Caller must initialize and free *SCRATCH.  If the return value is
 189    negative, this function has sent a notfound response.  */
 190 static time_t
 191 addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
 192                  const char *key, uid_t uid, struct hashentry *he,
 193                  struct datahead *dh, struct addgetnetgrentX_scratch *scratch)
 194 {
 195   if (__glibc_unlikely (debug_level > 0))
 196     {
 197       if (he == NULL)
 198         dbg_log (_("Haven't found \"%s\" in netgroup cache!"), key);
 199       else
 200         dbg_log (_("Reloading \"%s\" in netgroup cache!"), key);
 201     }
 202
 203   static nss_action_list netgroup_database;
 204   time_t timeout;
 205   struct dataset *dataset;
 206   bool cacheable = false;
 207   ssize_t total;
 208   bool found = false;
 209
 210   char *key_copy = NULL;
 211   struct __netgrent data;
 212   size_t nentries = 0;
 213   size_t group_len = strlen (key) + 1;
 214   struct name_list *first_needed
 215     = alloca (sizeof (struct name_list) + group_len);
 216
 217   if (netgroup_database == NULL
 218       && !__nss_database_get (nss_database_netgroup, &netgroup_database))
 219     {
 220       /* No such service.  */
 221       cacheable = do_notfound (db, fd, req, key, &dataset, &total, &timeout,
 222                                &key_copy);
 223       goto maybe_cache_add;
 224     }
 225
 226   memset (&data, '\0', sizeof (data));
 227   first_needed->next = first_needed;
 228   memcpy (first_needed->name, key, group_len);
 229   data.needed_groups = first_needed;
 230
 231   while (data.needed_groups != NULL)
 232     {
 233       /* Add the next group to the list of those which are known.  */
 234       struct name_list *this_group = data.needed_groups->next;
 235       if (this_group == data.needed_groups)
 236         data.needed_groups = NULL;
 237       else
 238         data.needed_groups->next = this_group->next;
 239       this_group->next = data.known_groups;
 240       data.known_groups = this_group;
 241
 242       union
 243       {
 244         enum nss_status (*f) (const char *, struct __netgrent *);
 245         void *ptr;
 246       } setfct;
 247
 248       nss_action_list nip = netgroup_database;
 249       int no_more = __nss_lookup (&nip, "setnetgrent", NULL, &setfct.ptr);
 250       while (!no_more)
 251         {
 252           enum nss_status status
 253             = DL_CALL_FCT (*setfct.f, (data.known_groups->name, &data));
 254
 255           if (status == NSS_STATUS_SUCCESS)
 256             {
 257               found = true;
 258               union
 259               {
 260                 enum nss_status (*f) (struct __netgrent *, char *, size_t,
 261                                       int *);
 262                 void *ptr;
 263               } getfct;
 264               getfct.ptr = __nss_lookup_function (nip, "getnetgrent_r");
 265               if (getfct.f != NULL)
 266                 while (1)
 267                   {
 268                     int e;
 269                     status = getfct.f (&data, scratch->tmp.data,
 270                                        scratch->tmp.length, &e);
 271                     if (status == NSS_STATUS_SUCCESS)
 272                       {
 273                         if (data.type == triple_val)
 274                           {
 275                             const char *nhost = data.val.triple.host;
 276                             const char *nuser = data.val.triple.user;
 277                             const char *ndomain = data.val.triple.domain;
 278                             if (!(addgetnetgrentX_append (scratch, nhost)
 279                                   && addgetnetgrentX_append (scratch, nuser)
 280                                   && addgetnetgrentX_append (scratch, ndomain)))
 281                               return send_notfound (fd);
 282                             ++nentries;
 283                           }
 284                         else
 285                           {
 286                             /* Check that the group has not been
 287                                requested before.  */
 288                             struct name_list *runp = data.needed_groups;
 289                             if (runp != NULL)
 290                               while (1)
 291                                 {
 292                                   if (strcmp (runp->name, data.val.group) == 0)
 293                                     break;
 294
 295                                   runp = runp->next;
 296                                   if (runp == data.needed_groups)
 297                                     {
 298                                       runp = NULL;
 299                                       break;
 300                                     }
 301                                 }
 302
 303                             if (runp == NULL)
 304                               {
 305                                 runp = data.known_groups;
 306                                 while (runp != NULL)
 307                                   if (strcmp (runp->name, data.val.group) == 0)
 308                                     break;
 309                                   else
 310                                     runp = runp->next;
 311                                 }
 312
 313                             if (runp == NULL)
 314                               {
 315                                 /* A new group is requested.  */
 316                                 size_t namelen = strlen (data.val.group) + 1;
 317                                 struct name_list *newg = alloca (sizeof (*newg)
 318                                                                  + namelen);
 319                                 memcpy (newg->name, data.val.group, namelen);
 320                                 if (data.needed_groups == NULL)
 321                                   data.needed_groups = newg->next = newg;
 322                                 else
 323                                   {
 324                                     newg->next = data.needed_groups->next;
 325                                     data.needed_groups->next = newg;
 326                                     data.needed_groups = newg;
 327                                   }
 328                               }
 329                           }
 330                       }
 331                     else if (status == NSS_STATUS_TRYAGAIN && e == ERANGE)
 332                       {
 333                         if (!scratch_buffer_grow (&scratch->tmp))
 334                           return send_notfound (fd);
 335                       }
 336                     else if (status == NSS_STATUS_RETURN
 337                              || status == NSS_STATUS_NOTFOUND
 338                              || status == NSS_STATUS_UNAVAIL)
 339                       /* This was either the last one for this group or the
 340                          group was empty or the NSS module had an internal
 341                          failure.  Look at next group if available.  */
 342                       break;
 343                   }
 344
 345               enum nss_status (*endfct) (struct __netgrent *);
 346               endfct = __nss_lookup_function (nip, "endnetgrent");
 347               if (endfct != NULL)
 348                 (void) DL_CALL_FCT (*endfct, (&data));
 349
 350               break;
 351             }
 352
 353           no_more = __nss_next2 (&nip, "setnetgrent", NULL, &setfct.ptr,
 354                                  status, 0);
 355         }
 356     }
 357
 358   /* No results.  Return a failure and write out a notfound record in the
 359      cache.  */
 360   if (!found)
 361     {
 362       cacheable = do_notfound (db, fd, req, key, &dataset, &total, &timeout,
 363                                &key_copy);
 364       goto maybe_cache_add;
 365     }
 366
 367   /* Capture the result size without the key appended.   */
 368   total = scratch->buffer_used;
 369
 370   /* Make a copy of the key.  The scratch buffer must not move after
 371      this point.  */
 372   key_copy = addgetnetgrentX_append_n (scratch, key, req->key_len);
 373   if (key_copy == NULL)
 374     return send_notfound (fd);
 375
 376   /* Fill in the dataset.  */
 377   dataset = scratch->buffer.data;
 378   timeout = datahead_init_pos (&dataset->head, total + req->key_len,
 379                                total - offsetof (struct dataset, resp),
 380                                he == NULL ? 0 : dh->nreloads + 1,
 381                                db->postimeout);
 382
 383   dataset->resp.version = NSCD_VERSION;
 384   dataset->resp.found = 1;
 385   dataset->resp.nresults = nentries;
 386   dataset->resp.result_len = total - sizeof (*dataset);
 387
 388   /* Now we can determine whether on refill we have to create a new
 389      record or not.  */
 390   if (he != NULL)
 391     {
 392       assert (fd == -1);
 393
 394       if (dataset->head.allocsize == dh->allocsize
 395           && dataset->head.recsize == dh->recsize
 396           && memcmp (&dataset->resp, dh->data,
 397                      dh->allocsize - offsetof (struct dataset, resp)) == 0)
 398         {
 399           /* The data has not changed.  We will just bump the timeout
 400              value.  Note that the new record has been allocated on
 401              the stack and need not be freed.  */
 402           dh->timeout = dataset->head.timeout;
 403           dh->ttl = dataset->head.ttl;
 404           ++dh->nreloads;
 405           dataset = (struct dataset *) dh;
 406
 407           goto out;
 408         }
 409     }
 410
 411   {
 412     struct dataset *newp
 413       = (struct dataset *) mempool_alloc (db, total + req->key_len, 1);
 414     if (__glibc_likely (newp != NULL))
 415       {
 416         /* Adjust pointer into the memory block.  */
 417         key_copy = (char *) newp + (key_copy - (char *) dataset);
 418
 419         dataset = memcpy (newp, dataset, total + req->key_len);
 420         cacheable = true;
 421
 422         if (he != NULL)
 423           /* Mark the old record as obsolete.  */
 424           dh->usable = false;
 425       }
 426   }
 427
 428   if (he == NULL && fd != -1)
 429     /* We write the dataset before inserting it to the database since
 430        while inserting this thread might block and so would
 431        unnecessarily let the receiver wait.  */
 432       writeall (fd, &dataset->resp, dataset->head.recsize);
 433
 434  maybe_cache_add:
 435   if (cacheable)
 436     {
 437       /* If necessary, we also propagate the data to disk.  */
 438       if (db->persistent)
 439         {
 440           // XXX async OK?
 441           uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 442           msync ((void *) pval,
 443                  ((uintptr_t) dataset & pagesize_m1) + total + req->key_len,
 444                  MS_ASYNC);
 445         }
 446
 447       (void) cache_add (req->type, key_copy, req->key_len, &dataset->head,
 448                         true, db, uid, he == NULL);
 449
 450       pthread_rwlock_unlock (&db->lock);
 451
 452       /* Mark the old entry as obsolete.  */
 453       if (dh != NULL)
 454         dh->usable = false;
 455     }
 456
 457  out:
 458   scratch->dataset = dataset;
 459
 460   return timeout;
 461 }
 462
 463
 464 static time_t
 465 addinnetgrX (struct database_dyn *db, int fd, request_header *req,
 466              char *key, uid_t uid, struct hashentry *he,
 467              struct datahead *dh)
 468 {
 469   const char *group = key;
 470   key = strchr (key, '\0') + 1;
 471   size_t group_len = key - group;
 472   const char *host = *key++ ? key : NULL;
 473   if (host != NULL)
 474     key = strchr (key, '\0') + 1;
 475   const char *user = *key++ ? key : NULL;
 476   if (user != NULL)
 477     key = strchr (key, '\0') + 1;
 478   const char *domain = *key++ ? key : NULL;
 479   struct addgetnetgrentX_scratch scratch;
 480
 481   addgetnetgrentX_scratch_init (&scratch);
 482
 483   if (__glibc_unlikely (debug_level > 0))
 484     {
 485       if (he == NULL)
 486         dbg_log (_("Haven't found \"%s (%s,%s,%s)\" in netgroup cache!"),
 487                  group, host ?: "", user ?: "", domain ?: "");
 488       else
 489         dbg_log (_("Reloading \"%s (%s,%s,%s)\" in netgroup cache!"),
 490                  group, host ?: "", user ?: "", domain ?: "");
 491     }
 492
 493   struct dataset *result = (struct dataset *) cache_search (GETNETGRENT,
 494                                                             group, group_len,
 495                                                             db, uid);
 496   time_t timeout;
 497   if (result != NULL)
 498     timeout = result->head.timeout;
 499   else
 500     {
 501       request_header req_get =
 502         {
 503           .type = GETNETGRENT,
 504           .key_len = group_len
 505         };
 506       timeout = addgetnetgrentX (db, -1, &req_get, group, uid, NULL, NULL,
 507                                  &scratch);
 508       result = scratch.dataset;
 509       if (timeout < 0)
 510         goto out;
 511     }
 512
 513   struct indataset
 514   {
 515     struct datahead head;
 516     innetgroup_response_header resp;
 517   } *dataset
 518       = (struct indataset *) mempool_alloc (db,
 519                                             sizeof (*dataset) + req->key_len,
 520                                             1);
 521   bool cacheable = true;
 522   if (__glibc_unlikely (dataset == NULL))
 523     {
 524       cacheable = false;
 525       /* The alloca is safe because nscd_run_worker verifies that
 526          key_len is not larger than MAXKEYLEN.  */
 527       dataset = alloca (sizeof (*dataset) + req->key_len);
 528     }
 529
 530   datahead_init_pos (&dataset->head, sizeof (*dataset) + req->key_len,
 531                      sizeof (innetgroup_response_header),
 532                      he == NULL ? 0 : dh->nreloads + 1,
 533                      result == NULL ? db->negtimeout : result->head.ttl);
 534   /* Set the notfound status and timeout based on the result from
 535      getnetgrent.  */
 536   dataset->head.notfound = result == NULL || result->head.notfound;
 537   dataset->head.timeout = timeout;
 538
 539   dataset->resp.version = NSCD_VERSION;
 540   dataset->resp.found = result != NULL && result->resp.found;
 541   /* Until we find a matching entry the result is 0.  */
 542   dataset->resp.result = 0;
 543
 544   char *key_copy = memcpy ((char *) (dataset + 1), group, req->key_len);
 545
 546   if (dataset->resp.found)
 547     {
 548       const char *triplets = (const char *) (&result->resp + 1);
 549
 550       for (nscd_ssize_t i = result->resp.nresults; i > 0; --i)
 551         {
 552           bool success = true;
 553
 554           /* For the host, user and domain in each triplet, we assume success
 555              if the value is blank because that is how the wildcard entry to
 556              match anything is stored in the netgroup cache.  */
 557           if (host != NULL && *triplets != '\0')
 558             success = strcmp (host, triplets) == 0;
 559           triplets = strchr (triplets, '\0') + 1;
 560
 561           if (success && user != NULL && *triplets != '\0')
 562             success = strcmp (user, triplets) == 0;
 563           triplets = strchr (triplets, '\0') + 1;
 564
 565           if (success && (domain == NULL || *triplets == '\0'
 566                           || strcmp (domain, triplets) == 0))
 567             {
 568               dataset->resp.result = 1;
 569               break;
 570             }
 571           triplets = strchr (triplets, '\0') + 1;
 572         }
 573     }
 574
 575   if (he != NULL && dh->data[0].innetgroupdata.result == dataset->resp.result)
 576     {
 577       /* The data has not changed.  We will just bump the timeout
 578          value.  Note that the new record has been allocated on
 579          the stack and need not be freed.  */
 580       dh->timeout = timeout;
 581       dh->ttl = dataset->head.ttl;
 582       ++dh->nreloads;
 583       if (cacheable)
 584         pthread_rwlock_unlock (&db->lock);
 585       goto out;
 586     }
 587
 588   /* addgetnetgrentX may have already sent a notfound response.  Do
 589      not send another one.  */
 590   if (he == NULL && dataset->resp.found)
 591     {
 592       /* We write the dataset before inserting it to the database
 593          since while inserting this thread might block and so would
 594          unnecessarily let the receiver wait.  */
 595       assert (fd != -1);
 596
 597       writeall (fd, &dataset->resp, sizeof (innetgroup_response_header));
 598     }
 599
 600   if (cacheable)
 601     {
 602       /* If necessary, we also propagate the data to disk.  */
 603       if (db->persistent)
 604         {
 605           // XXX async OK?
 606           uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 607           msync ((void *) pval,
 608                  ((uintptr_t) dataset & pagesize_m1) + sizeof (*dataset)
 609                  + req->key_len,
 610                  MS_ASYNC);
 611         }
 612
 613       (void) cache_add (req->type, key_copy, req->key_len, &dataset->head,
 614                         true, db, uid, he == NULL);
 615
 616       pthread_rwlock_unlock (&db->lock);
 617
 618       /* Mark the old entry as obsolete.  */
 619       if (dh != NULL)
 620         dh->usable = false;
 621     }
 622
 623  out:
 624   addgetnetgrentX_scratch_free (&scratch);
 625   return timeout;
 626 }
 627
 628
 629 static time_t
 630 addgetnetgrentX_ignore (struct database_dyn *db, int fd, request_header *req,
 631                         const char *key, uid_t uid, struct hashentry *he,
 632                         struct datahead *dh)
 633 {
 634   struct addgetnetgrentX_scratch scratch;
 635   addgetnetgrentX_scratch_init (&scratch);
 636   time_t timeout = addgetnetgrentX (db, fd, req, key, uid, he, dh, &scratch);
 637   addgetnetgrentX_scratch_free (&scratch);
 638   if (timeout < 0)
 639     timeout = 0;
 640   return timeout;
 641 }
 642
 643 void
 644 addgetnetgrent (struct database_dyn *db, int fd, request_header *req,
 645                 void *key, uid_t uid)
 646 {
 647   addgetnetgrentX_ignore (db, fd, req, key, uid, NULL, NULL);
 648 }
 649
 650
 651 time_t
 652 readdgetnetgrent (struct database_dyn *db, struct hashentry *he,
 653                   struct datahead *dh)
 654 {
 655   request_header req =
 656     {
 657       .type = GETNETGRENT,
 658       .key_len = he->len
 659     };
 660   return addgetnetgrentX_ignore
 661     (db, -1, &req, db->data + he->key, he->owner, he, dh);
 662 }
 663
 664
 665 void
 666 addinnetgr (struct database_dyn *db, int fd, request_header *req,
 667             void *key, uid_t uid)
 668 {
 669   addinnetgrX (db, fd, req, key, uid, NULL, NULL);
 670 }
 671
 672
 673 time_t
 674 readdinnetgr (struct database_dyn *db, struct hashentry *he,
 675               struct datahead *dh)
 676 {
 677   request_header req =
 678     {
 679       .type = INNETGR,
 680       .key_len = he->len
 681     };
 682
 683   time_t timeout = addinnetgrX (db, -1, &req, db->data + he->key, he->owner,
 684                                 he, dh);
 685   if (timeout < 0)
 686     timeout = 0;
 687   return timeout;
 688 }