nscd/initgrcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 2004-2013 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, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <assert.h>
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <libintl.h>
  23 #include <string.h>
  24 #include <time.h>
  25 #include <unistd.h>
  26 #include <sys/mman.h>
  27
  28 #include "dbg_log.h"
  29 #include "nscd.h"
  30 #ifdef HAVE_SENDFILE
  31 # include <kernel-features.h>
  32 #endif
  33
  34 #include "../nss/nsswitch.h"
  35
  36
  37 /* Type of the lookup function.  */
  38 typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t,
  39                                                     long int *, long int *,
  40                                                     gid_t **, long int, int *);
  41
  42
  43 static const initgr_response_header notfound =
  44 {
  45   .version = NSCD_VERSION,
  46   .found = 0,
  47   .ngrps = 0
  48 };
  49
  50
  51 #include "../grp/compat-initgroups.c"
  52
  53
  54 static time_t
  55 addinitgroupsX (struct database_dyn *db, int fd, request_header *req,
  56                 void *key, uid_t uid, struct hashentry *const he,
  57                 struct datahead *dh)
  58 {
  59   /* Search for the entry matching the key.  Please note that we don't
  60      look again in the table whether the dataset is now available.  We
  61      simply insert it.  It does not matter if it is in there twice.  The
  62      pruning function only will look at the timestamp.  */
  63
  64
  65   /* We allocate all data in one memory block: the iov vector,
  66      the response header and the dataset itself.  */
  67   struct dataset
  68   {
  69     struct datahead head;
  70     initgr_response_header resp;
  71     char strdata[0];
  72   } *dataset = NULL;
  73
  74   if (__builtin_expect (debug_level > 0, 0))
  75     {
  76       if (he == NULL)
  77         dbg_log (_("Haven't found \"%s\" in group cache!"), (char *) key);
  78       else
  79         dbg_log (_("Reloading \"%s\" in group cache!"), (char *) key);
  80     }
  81
  82   static service_user *group_database;
  83   service_user *nip;
  84   int no_more;
  85
  86   if (group_database == NULL)
  87     no_more = __nss_database_lookup ("group", NULL,
  88                                      "compat [NOTFOUND=return] files",
  89                                      &group_database);
  90   else
  91     no_more = 0;
  92   nip = group_database;
  93
  94  /* We always use sysconf even if NGROUPS_MAX is defined.  That way, the
  95      limit can be raised in the kernel configuration without having to
  96      recompile libc.  */
  97   long int limit = __sysconf (_SC_NGROUPS_MAX);
  98
  99   long int size;
 100   if (limit > 0)
 101     /* We limit the size of the intially allocated array.  */
 102     size = MIN (limit, 64);
 103   else
 104     /* No fixed limit on groups.  Pick a starting buffer size.  */
 105     size = 16;
 106
 107   long int start = 0;
 108   bool all_tryagain = true;
 109   bool any_success = false;
 110
 111   /* This is temporary memory, we need not (and must not) call
 112      mempool_alloc.  */
 113   // XXX This really should use alloca.  need to change the backends.
 114   gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t));
 115   if (__builtin_expect (groups == NULL, 0))
 116     /* No more memory.  */
 117     goto out;
 118
 119   /* Nothing added yet.  */
 120   while (! no_more)
 121     {
 122       long int prev_start = start;
 123       enum nss_status status;
 124       initgroups_dyn_function fct;
 125       fct = __nss_lookup_function (nip, "initgroups_dyn");
 126
 127       if (fct == NULL)
 128         {
 129           status = compat_call (nip, key, -1, &start, &size, &groups,
 130                                 limit, &errno);
 131
 132           if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE)
 133             break;
 134         }
 135       else
 136         status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups,
 137                                     limit, &errno));
 138
 139       /* Remove duplicates.  */
 140       long int cnt = prev_start;
 141       while (cnt < start)
 142         {
 143           long int inner;
 144           for (inner = 0; inner < prev_start; ++inner)
 145             if (groups[inner] == groups[cnt])
 146               break;
 147
 148           if (inner < prev_start)
 149             groups[cnt] = groups[--start];
 150           else
 151             ++cnt;
 152         }
 153
 154       if (status != NSS_STATUS_TRYAGAIN)
 155         all_tryagain = false;
 156
 157       /* This is really only for debugging.  */
 158       if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN)
 159         __libc_fatal ("illegal status in internal_getgrouplist");
 160
 161       any_success |= status == NSS_STATUS_SUCCESS;
 162
 163       if (status != NSS_STATUS_SUCCESS
 164           && nss_next_action (nip, status) == NSS_ACTION_RETURN)
 165          break;
 166
 167       if (nip->next == NULL)
 168         no_more = -1;
 169       else
 170         nip = nip->next;
 171     }
 172
 173   bool all_written;
 174   ssize_t total;
 175   time_t timeout;
 176  out:
 177   all_written = true;
 178   timeout = MAX_TIMEOUT_VALUE;
 179   if (!any_success)
 180     {
 181       /* Nothing found.  Create a negative result record.  */
 182       total = sizeof (notfound);
 183
 184       if (he != NULL && all_tryagain)
 185         {
 186           /* If we have an old record available but cannot find one now
 187              because the service is not available we keep the old record
 188              and make sure it does not get removed.  */
 189           if (reload_count != UINT_MAX && dh->nreloads == reload_count)
 190             /* Do not reset the value if we never not reload the record.  */
 191             dh->nreloads = reload_count - 1;
 192
 193           /* Reload with the same time-to-live value.  */
 194           timeout = dh->timeout = time (NULL) + db->postimeout;
 195         }
 196       else
 197         {
 198           /* We have no data.  This means we send the standard reply for this
 199              case.  */
 200           if (fd != -1
 201               && TEMP_FAILURE_RETRY (send (fd, &notfound, total,
 202                                            MSG_NOSIGNAL)) != total)
 203             all_written = false;
 204
 205           /* If we have a transient error or cannot permanently store
 206              the result, so be it.  */
 207           if (all_tryagain || __builtin_expect (db->negtimeout == 0, 0))
 208             {
 209               /* Mark the old entry as obsolete.  */
 210               if (dh != NULL)
 211                 dh->usable = false;
 212             }
 213           else if ((dataset = mempool_alloc (db, (sizeof (struct dataset)
 214                                                   + req->key_len), 1)) != NULL)
 215             {
 216               dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
 217               dataset->head.recsize = total;
 218               dataset->head.notfound = true;
 219               dataset->head.nreloads = 0;
 220               dataset->head.usable = true;
 221
 222               /* Compute the timeout time.  */
 223               timeout = dataset->head.timeout = time (NULL) + db->negtimeout;
 224
 225               /* This is the reply.  */
 226               memcpy (&dataset->resp, &notfound, total);
 227
 228               /* Copy the key data.  */
 229               char *key_copy = memcpy (dataset->strdata, key, req->key_len);
 230
 231               /* If necessary, we also propagate the data to disk.  */
 232               if (db->persistent)
 233                 {
 234                   // XXX async OK?
 235                   uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 236                   msync ((void *) pval,
 237                          ((uintptr_t) dataset & pagesize_m1)
 238                          + sizeof (struct dataset) + req->key_len, MS_ASYNC);
 239                 }
 240
 241               (void) cache_add (req->type, key_copy, req->key_len,
 242                                 &dataset->head, true, db, uid, he == NULL);
 243
 244               pthread_rwlock_unlock (&db->lock);
 245
 246               /* Mark the old entry as obsolete.  */
 247               if (dh != NULL)
 248                 dh->usable = false;
 249             }
 250         }
 251     }
 252   else
 253     {
 254
 255       total = offsetof (struct dataset, strdata) + start * sizeof (int32_t);
 256
 257       /* If we refill the cache, first assume the reconrd did not
 258          change.  Allocate memory on the cache since it is likely
 259          discarded anyway.  If it turns out to be necessary to have a
 260          new record we can still allocate real memory.  */
 261       bool alloca_used = false;
 262       dataset = NULL;
 263
 264       if (he == NULL)
 265         dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
 266                                                     1);
 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       timeout = 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                                                     1);
 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
 347               /* Mark the old record as obsolete.  */
 348               dh->usable = false;
 349             }
 350         }
 351       else
 352         {
 353           /* We write the dataset before inserting it to the database
 354              since while inserting this thread might block and so would
 355              unnecessarily let the receiver wait.  */
 356           assert (fd != -1);
 357
 358 #ifdef HAVE_SENDFILE
 359           if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
 360             {
 361               assert (db->wr_fd != -1);
 362               assert ((char *) &dataset->resp > (char *) db->data);
 363               assert ((char *) dataset - (char *) db->head
 364                       + total
 365                       <= (sizeof (struct database_pers_head)
 366                           + db->head->module * sizeof (ref_t)
 367                           + db->head->data_size));
 368               ssize_t written = sendfileall (fd, db->wr_fd,
 369                                              (char *) &dataset->resp
 370                                              - (char *) db->head,
 371                                              dataset->head.recsize);
 372               if (written != dataset->head.recsize)
 373                 {
 374 # ifndef __ASSUME_SENDFILE
 375                   if (written == -1 && errno == ENOSYS)
 376                     goto use_write;
 377 # endif
 378                   all_written = false;
 379                 }
 380             }
 381           else
 382 # ifndef __ASSUME_SENDFILE
 383           use_write:
 384 # endif
 385 #endif
 386             if (writeall (fd, &dataset->resp, dataset->head.recsize)
 387                 != dataset->head.recsize)
 388               all_written = false;
 389         }
 390
 391
 392       /* Add the record to the database.  But only if it has not been
 393          stored on the stack.  */
 394       if (! alloca_used)
 395         {
 396           /* If necessary, we also propagate the data to disk.  */
 397           if (db->persistent)
 398             {
 399               // XXX async OK?
 400               uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 401               msync ((void *) pval,
 402                      ((uintptr_t) dataset & pagesize_m1) + total +
 403                      req->key_len, MS_ASYNC);
 404             }
 405
 406           (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
 407                             db, uid, he == NULL);
 408
 409           pthread_rwlock_unlock (&db->lock);
 410         }
 411     }
 412
 413   free (groups);
 414
 415   if (__builtin_expect (!all_written, 0) && debug_level > 0)
 416     {
 417       char buf[256];
 418       dbg_log (_("short write in %s: %s"), __FUNCTION__,
 419                strerror_r (errno, buf, sizeof (buf)));
 420     }
 421
 422   return timeout;
 423 }
 424
 425
 426 void
 427 addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
 428                uid_t uid)
 429 {
 430   addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
 431 }
 432
 433
 434 time_t
 435 readdinitgroups (struct database_dyn *db, struct hashentry *he,
 436                  struct datahead *dh)
 437 {
 438   request_header req =
 439     {
 440       .type = INITGROUPS,
 441       .key_len = he->len
 442     };
 443
 444   return addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
 445 }