nscd/initgrcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 2004, 2005, 2006 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           /* If we cannot permanently store the result, so be it.  */
 202           if (dataset != NULL)
 203             {
 204               dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
 205               dataset->head.recsize = total;
 206               dataset->head.notfound = true;
 207               dataset->head.nreloads = 0;
 208               dataset->head.usable = true;
 209
 210               /* Compute the timeout time.  */
 211               dataset->head.timeout = time (NULL) + db->negtimeout;
 212
 213               /* This is the reply.  */
 214               memcpy (&dataset->resp, &notfound, total);
 215
 216               /* Copy the key data.  */
 217               char *key_copy = memcpy (dataset->strdata, key, req->key_len);
 218
 219               /* If necessary, we also propagate the data to disk.  */
 220               if (db->persistent)
 221                 {
 222                   // XXX async OK?
 223                   uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 224                   msync ((void *) pval,
 225                          ((uintptr_t) dataset & pagesize_m1)
 226                          + sizeof (struct dataset) + req->key_len, MS_ASYNC);
 227                 }
 228
 229               /* Now get the lock to safely insert the records.  */
 230               pthread_rwlock_rdlock (&db->lock);
 231
 232               if (cache_add (req->type, key_copy, req->key_len,
 233                              &dataset->head, true, db, uid) < 0)
 234                 /* Ensure the data can be recovered.  */
 235                 dataset->head.usable = false;
 236
 237               pthread_rwlock_unlock (&db->lock);
 238
 239               /* Mark the old entry as obsolete.  */
 240               if (dh != NULL)
 241                 dh->usable = false;
 242             }
 243           else
 244             ++db->head->addfailed;
 245         }
 246     }
 247   else
 248     {
 249
 250       written = total = sizeof (struct dataset) + 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           if (dataset == NULL)
 264             ++db->head->addfailed;
 265         }
 266
 267       if (dataset == NULL)
 268         {
 269           /* We cannot permanently add the result in the moment.  But
 270              we can provide the result as is.  Store the data in some
 271              temporary memory.  */
 272           dataset = (struct dataset *) alloca (total + req->key_len);
 273
 274           /* We cannot add this record to the permanent database.  */
 275           alloca_used = true;
 276         }
 277
 278       dataset->head.allocsize = total + req->key_len;
 279       dataset->head.recsize = total - offsetof (struct dataset, resp);
 280       dataset->head.notfound = false;
 281       dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
 282       dataset->head.usable = true;
 283
 284       /* Compute the timeout time.  */
 285       dataset->head.timeout = time (NULL) + db->postimeout;
 286
 287       dataset->resp.version = NSCD_VERSION;
 288       dataset->resp.found = 1;
 289       dataset->resp.ngrps = start;
 290
 291       char *cp = dataset->strdata;
 292
 293       /* Copy the GID values.  If the size of the types match this is
 294          very simple.  */
 295       if (sizeof (gid_t) == sizeof (int32_t))
 296         cp = mempcpy (cp, groups, start * sizeof (gid_t));
 297       else
 298         {
 299           gid_t *gcp = (gid_t *) cp;
 300
 301           for (int i = 0; i < start; ++i)
 302             *gcp++ = groups[i];
 303
 304           cp = (char *) gcp;
 305         }
 306
 307       /* Finally the user name.  */
 308       memcpy (cp, key, req->key_len);
 309
 310       /* Now we can determine whether on refill we have to create a new
 311          record or not.  */
 312       if (he != NULL)
 313         {
 314           assert (fd == -1);
 315
 316           if (total + req->key_len == dh->allocsize
 317               && total - offsetof (struct dataset, resp) == dh->recsize
 318               && memcmp (&dataset->resp, dh->data,
 319                          dh->allocsize - offsetof (struct dataset, resp)) == 0)
 320             {
 321               /* The data has not changed.  We will just bump the
 322                  timeout value.  Note that the new record has been
 323                  allocated on the stack and need not be freed.  */
 324               dh->timeout = dataset->head.timeout;
 325               ++dh->nreloads;
 326             }
 327           else
 328             {
 329               /* We have to create a new record.  Just allocate
 330                  appropriate memory and copy it.  */
 331               struct dataset *newp
 332                 = (struct dataset *) mempool_alloc (db, total + req->key_len);
 333               if (newp != NULL)
 334                 {
 335                   /* Adjust pointer into the memory block.  */
 336                   cp = (char *) newp + (cp - (char *) dataset);
 337
 338                   dataset = memcpy (newp, dataset, total + req->key_len);
 339                   alloca_used = false;
 340                 }
 341               else
 342                 ++db->head->addfailed;
 343
 344               /* Mark the old record as obsolete.  */
 345               dh->usable = false;
 346             }
 347         }
 348       else
 349         {
 350           /* We write the dataset before inserting it to the database
 351              since while inserting this thread might block and so would
 352              unnecessarily let the receiver wait.  */
 353           assert (fd != -1);
 354
 355 #ifdef HAVE_SENDFILE
 356           if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
 357             {
 358               assert (db->wr_fd != -1);
 359               assert ((char *) &dataset->resp > (char *) db->data);
 360               assert ((char *) &dataset->resp - (char *) db->head
 361                       + total
 362                       <= (sizeof (struct database_pers_head)
 363                           + db->head->module * sizeof (ref_t)
 364                           + db->head->data_size));
 365               written = sendfileall (fd, db->wr_fd,
 366                                      (char *) &dataset->resp
 367                                      - (char *) db->head, total);
 368 # ifndef __ASSUME_SENDFILE
 369               if (written == -1 && errno == ENOSYS)
 370                 goto use_write;
 371 # endif
 372             }
 373           else
 374 # ifndef __ASSUME_SENDFILE
 375           use_write:
 376 # endif
 377 #endif
 378             written = writeall (fd, &dataset->resp, total);
 379         }
 380
 381
 382       /* Add the record to the database.  But only if it has not been
 383          stored on the stack.  */
 384       if (! alloca_used)
 385         {
 386           /* If necessary, we also propagate the data to disk.  */
 387           if (db->persistent)
 388             {
 389               // XXX async OK?
 390               uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 391               msync ((void *) pval,
 392                      ((uintptr_t) dataset & pagesize_m1) + total +
 393                      req->key_len, MS_ASYNC);
 394             }
 395
 396           /* Now get the lock to safely insert the records.  */
 397           pthread_rwlock_rdlock (&db->lock);
 398
 399           if (cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
 400                          db, uid) < 0)
 401             /* Could not allocate memory.  Make sure the data gets
 402                discarded.  */
 403             dataset->head.usable = false;
 404
 405           pthread_rwlock_unlock (&db->lock);
 406         }
 407     }
 408
 409   free (groups);
 410
 411   if (__builtin_expect (written != total, 0) && debug_level > 0)
 412     {
 413       char buf[256];
 414       dbg_log (_("short write in %s: %s"), __FUNCTION__,
 415                strerror_r (errno, buf, sizeof (buf)));
 416     }
 417 }
 418
 419
 420 void
 421 addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
 422                uid_t uid)
 423 {
 424   addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
 425 }
 426
 427
 428 void
 429 readdinitgroups (struct database_dyn *db, struct hashentry *he,
 430                  struct datahead *dh)
 431 {
 432   request_header req =
 433     {
 434       .type = INITGROUPS,
 435       .key_len = he->len
 436     };
 437
 438   addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
 439 }