nscd/initgrcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 2004, 2005, 2006, 2008 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published
   8    by the Free Software Foundation; version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <libintl.h>
  24 #include <string.h>
  25 #include <time.h>
  26 #include <unistd.h>
  27 #include <sys/mman.h>
  28
  29 #include "dbg_log.h"
  30 #include "nscd.h"
  31 #ifdef HAVE_SENDFILE
  32 # include <kernel-features.h>
  33 #endif
  34
  35 #include "../nss/nsswitch.h"
  36
  37
  38 /* Type of the lookup function.  */
  39 typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
  40                                                     long int *, long int *,
  41                                                     gid_t **, long int, int *);
  42
  43
  44 static const initgr_response_header notfound =
  45 {
  46   .version = NSCD_VERSION,
  47   .found = 0,
  48   .ngrps = 0
  49 };
  50
  51
  52 #include "../grp/compat-initgroups.c"
  53
  54
  55 static void
  56 addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
  57                 void *key, uid_t uid, struct hashentry *he,
  58                 struct datahead *dh)
  59 {
  60   /* Search for the entry matching the key.  Please note that we don't
  61      look again in the table whether the dataset is now available.  We
  62      simply insert it.  It does not matter if it is in there twice.  The
  63      pruning function only will look at the timestamp.  */
  64
  65
  66   /* We allocate all data in one memory block: the iov vector,
  67      the response header and the dataset itself.  */
  68   struct dataset
  69   {
  70     struct datahead head;
  71     initgr_response_header resp;
  72     char strdata[0];
  73   } *dataset = NULL;
  74
  75   if (__builtin_expect (debug_level > 0, 0))
  76     {
  77       if (he == NULL)
  78         dbg_log (_("Haven't found \"%s\" in group cache!"), (char *) key);
  79       else
  80         dbg_log (_("Reloading \"%s\" in group cache!"), (char *) key);
  81     }
  82
  83   static service_user *group_database;
  84   service_user *nip = NULL;
  85   int no_more;
  86
  87   if (group_database != NULL)
  88     {
  89       nip = group_database;
  90       no_more = 0;
  91     }
  92   else
  93     no_more = __nss_database_lookup ("group", NULL,
  94                                      "compat [NOTFOUND=return] files", &nip);
  95
  96  /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
  97      limit can be raised in the kernel configuration without having to
  98      recompile libc.  */
  99   long int limit = __sysconf (_SC_NGROUPS_MAX);
 100
 101   long int size;
 102   if (limit > 0)
 103     /* We limit the size of the intially allocated array.  */
 104     size = MIN (limit, 64);
 105   else
 106     /* No fixed limit on groups.  Pick a starting buffer size.  */
 107     size = 16;
 108
 109   long int start = 0;
 110   bool all_tryagain = true;
 111   bool any_success = false;
 112
 113   /* This is temporary memory, we need not (and must not) call
 114      mempool_alloc.  */
 115   // XXX This really should use alloca.  need to change the backends.
 116   gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t));
 117   if (__builtin_expect (groups == NULL, 0))
 118     /* No more memory.  */
 119     goto out;
 120
 121   /* Nothing added yet.  */
 122   while (! no_more)
 123     {
 124       long int prev_start = start;
 125       enum nss_status status;
 126       initgroups_dyn_function fct;
 127       fct = __nss_lookup_function (nip, "initgroups_dyn");
 128
 129       if (fct == NULL)
 130         {
 131           status = compat_call (nip, key, -1, &start, &size, &groups,
 132                                 limit, &errno);
 133
 134           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
 135             break;
 136         }
 137       else
 138         status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups,
 139                                     limit, &errno));
 140
 141       /* Remove duplicates.  */
 142       long int cnt = prev_start;
 143       while (cnt < start)
 144         {
 145           long int inner;
 146           for (inner = 0; inner < prev_start; ++inner)
 147             if (groups[inner] == groups[cnt])
 148               break;
 149
 150           if (inner < prev_start)
 151             groups[cnt] = groups[--start];
 152           else
 153             ++cnt;
 154         }
 155
 156       if (status != NSS_STATUS_TRYAGAIN)
 157         all_tryagain = false;
 158
 159       /* This is really only for debugging.  */
 160       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 161         __libc_fatal ("illegal status in internal_getgrouplist");
 162
 163       any_success |= status == NSS_STATUS_SUCCESS;
 164
 165       if (status != NSS_STATUS_SUCCESS
 166           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 167          break;
 168
 169       if (nip->next == NULL)
 170         no_more = -1;
 171       else
 172         nip = nip->next;
 173     }
 174
 175   ssize_t total;
 176   ssize_t written;
 177  out:
 178   if (!any_success)
 179     {
 180       /* Nothing found.  Create a negative result record.  */
 181       written = total = sizeof (notfound);
 182
 183       if (he != NULL && all_tryagain)
 184         {
 185           /* If we have an old record available but cannot find one now
 186              because the service is not available we keep the old record
 187              and make sure it does not get removed.  */
 188           if (reload_count != UINT_MAX && dh->nreloads == reload_count)
 189             /* Do not reset the value if we never not reload the record.  */
 190             dh->nreloads = reload_count - 1;
 191         }
 192       else
 193         {
 194           /* We have no data.  This means we send the standard reply for this
 195              case.  */
 196           if (fd != -1)
 197             written = TEMP_FAILURE_RETRY (send (fd, &notfound, total,
 198                                                 MSG_NOSIGNAL));
 199
 200           dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len,
 201                                    IDX_result_data);
 202           /* If we cannot permanently store the result, so be it.  */
 203           if (dataset != NULL)
 204             {
 205               dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
 206               dataset->head.recsize = total;
 207               dataset->head.notfound = true;
 208               dataset->head.nreloads = 0;
 209               dataset->head.usable = true;
 210
 211               /* Compute the timeout time.  */
 212               dataset->head.timeout = time (NULL) + db->negtimeout;
 213
 214               /* This is the reply.  */
 215               memcpy (&dataset->resp, &notfound, total);
 216
 217               /* Copy the key data.  */
 218               char *key_copy = memcpy (dataset->strdata, key, req->key_len);
 219
 220               /* If necessary, we also propagate the data to disk.  */
 221               if (db->persistent)
 222                 {
 223                   // XXX async OK?
 224                   uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 225                   msync ((void *) pval,
 226                          ((uintptr_t) dataset & pagesize_m1)
 227                          + sizeof (struct dataset) + req->key_len, MS_ASYNC);
 228                 }
 229
 230               /* Now get the lock to safely insert the records.  */
 231               pthread_rwlock_rdlock (&db->lock);
 232
 233               (void) cache_add (req->type, key_copy, req->key_len,
 234                                 &dataset->head, true, db, uid, he == NULL);
 235
 236               pthread_rwlock_unlock (&db->lock);
 237
 238               /* Mark the old entry as obsolete.  */
 239               if (dh != NULL)
 240                 dh->usable = false;
 241             }
 242           else
 243             ++db->head->addfailed;
 244         }
 245     }
 246   else
 247     {
 248
 249       written = total = (offsetof (struct dataset, strdata)
 250                          + start * sizeof (int32_t));
 251
 252       /* If we refill the cache, first assume the reconrd did not
 253          change.  Allocate memory on the cache since it is likely
 254          discarded anyway.  If it turns out to be necessary to have a
 255          new record we can still allocate real memory.  */
 256       bool alloca_used = false;
 257       dataset = NULL;
 258
 259       if (he == NULL)
 260         {
 261           dataset = (struct dataset *) mempool_alloc (db,
 262                                                       total + req->key_len,
 263                                                       IDX_result_data);
 264           if (dataset == NULL)
 265             ++db->head->addfailed;
 266         }
 267
 268       if (dataset == NULL)
 269         {
 270           /* We cannot permanently add the result in the moment.  But
 271              we can provide the result as is.  Store the data in some
 272              temporary memory.  */
 273           dataset = (struct dataset *) alloca (total + req->key_len);
 274
 275           /* We cannot add this record to the permanent database.  */
 276           alloca_used = true;
 277         }
 278
 279       dataset->head.allocsize = total + req->key_len;
 280       dataset->head.recsize = total - offsetof (struct dataset, resp);
 281       dataset->head.notfound = false;
 282       dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
 283       dataset->head.usable = true;
 284
 285       /* Compute the timeout time.  */
 286       dataset->head.timeout = time (NULL) + db->postimeout;
 287
 288       dataset->resp.version = NSCD_VERSION;
 289       dataset->resp.found = 1;
 290       dataset->resp.ngrps = start;
 291
 292       char *cp = dataset->strdata;
 293
 294       /* Copy the GID values.  If the size of the types match this is
 295          very simple.  */
 296       if (sizeof (gid_t) == sizeof (int32_t))
 297         cp = mempcpy (cp, groups, start * sizeof (gid_t));
 298       else
 299         {
 300           gid_t *gcp = (gid_t *) cp;
 301
 302           for (int i = 0; i < start; ++i)
 303             *gcp++ = groups[i];
 304
 305           cp = (char *) gcp;
 306         }
 307
 308       /* Finally the user name.  */
 309       memcpy (cp, key, req->key_len);
 310
 311       assert (cp == dataset->strdata + total - offsetof (struct dataset,
 312                                                          strdata));
 313
 314       /* Now we can determine whether on refill we have to create a new
 315          record or not.  */
 316       if (he != NULL)
 317         {
 318           assert (fd == -1);
 319
 320           if (total + req->key_len == dh->allocsize
 321               && total - offsetof (struct dataset, resp) == dh->recsize
 322               && memcmp (&dataset->resp, dh->data,
 323                          dh->allocsize - offsetof (struct dataset, resp)) == 0)
 324             {
 325               /* The data has not changed.  We will just bump the
 326                  timeout value.  Note that the new record has been
 327                  allocated on the stack and need not be freed.  */
 328               dh->timeout = dataset->head.timeout;
 329               ++dh->nreloads;
 330             }
 331           else
 332             {
 333               /* We have to create a new record.  Just allocate
 334                  appropriate memory and copy it.  */
 335               struct dataset *newp
 336                 = (struct dataset *) mempool_alloc (db, total + req->key_len,
 337                                                     IDX_result_data);
 338               if (newp != NULL)
 339                 {
 340                   /* Adjust pointer into the memory block.  */
 341                   cp = (char *) newp + (cp - (char *) dataset);
 342
 343                   dataset = memcpy (newp, dataset, total + req->key_len);
 344                   alloca_used = false;
 345                 }
 346               else
 347                 ++db->head->addfailed;
 348
 349               /* Mark the old record as obsolete.  */
 350               dh->usable = false;
 351             }
 352         }
 353       else
 354         {
 355           /* We write the dataset before inserting it to the database
 356              since while inserting this thread might block and so would
 357              unnecessarily let the receiver wait.  */
 358           assert (fd != -1);
 359
 360 #ifdef HAVE_SENDFILE
 361           if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
 362             {
 363               assert (db->wr_fd != -1);
 364               assert ((char *) &dataset->resp > (char *) db->data);
 365               assert ((char *) &dataset->resp - (char *) db->head
 366                       + total
 367                       <= (sizeof (struct database_pers_head)
 368                           + db->head->module * sizeof (ref_t)
 369                           + db->head->data_size));
 370               written = sendfileall (fd, db->wr_fd,
 371                                      (char *) &dataset->resp
 372                                      - (char *) db->head, total);
 373 # ifndef __ASSUME_SENDFILE
 374               if (written == -1 && errno == ENOSYS)
 375                 goto use_write;
 376 # endif
 377             }
 378           else
 379 # ifndef __ASSUME_SENDFILE
 380           use_write:
 381 # endif
 382 #endif
 383             written = writeall (fd, &dataset->resp, total);
 384         }
 385
 386
 387       /* Add the record to the database.  But only if it has not been
 388          stored on the stack.  */
 389       if (! alloca_used)
 390         {
 391           /* If necessary, we also propagate the data to disk.  */
 392           if (db->persistent)
 393             {
 394               // XXX async OK?
 395               uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 396               msync ((void *) pval,
 397                      ((uintptr_t) dataset & pagesize_m1) + total +
 398                      req->key_len, MS_ASYNC);
 399             }
 400
 401           /* Now get the lock to safely insert the records.  */
 402           pthread_rwlock_rdlock (&db->lock);
 403
 404           (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
 405                             db, uid, he == NULL);
 406
 407           pthread_rwlock_unlock (&db->lock);
 408         }
 409     }
 410
 411   free (groups);
 412
 413   if (__builtin_expect (written != total, 0) && debug_level > 0)
 414     {
 415       char buf[256];
 416       dbg_log (_("short write in %s: %s"), __FUNCTION__,
 417                strerror_r (errno, buf, sizeof (buf)));
 418     }
 419 }
 420
 421
 422 void
 423 addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
 424                uid_t uid)
 425 {
 426   addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
 427 }
 428
 429
 430 void
 431 readdinitgroups (struct database_dyn *db, struct hashentry *he,
 432                  struct datahead *dh)
 433 {
 434   request_header req =
 435     {
 436       .type = INITGROUPS,
 437       .key_len = he->len
 438     };
 439
 440   addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
 441 }