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               if (cache_add (req->type, key_copy, req->key_len,
 234                              &dataset->head, true, db, uid) < 0)
 235                 /* Ensure the data can be recovered.  */
 236                 dataset->head.usable = false;
 237
 238               pthread_rwlock_unlock (&db->lock);
 239
 240               /* Mark the old entry as obsolete.  */
 241               if (dh != NULL)
 242                 dh->usable = false;
 243             }
 244           else
 245             ++db->head->addfailed;
 246         }
 247     }
 248   else
 249     {
 250
 251       written = total = sizeof (struct dataset) + start * sizeof (int32_t);
 252
 253       /* If we refill the cache, first assume the reconrd did not
 254          change.  Allocate memory on the cache since it is likely
 255          discarded anyway.  If it turns out to be necessary to have a
 256          new record we can still allocate real memory.  */
 257       bool alloca_used = false;
 258       dataset = NULL;
 259
 260       if (he == NULL)
 261         {
 262           dataset = (struct dataset *) mempool_alloc (db,
 263                                                       total + req->key_len,
 264                                                       IDX_result_data);
 265           if (dataset == NULL)
 266             ++db->head->addfailed;
 267         }
 268
 269       if (dataset == NULL)
 270         {
 271           /* We cannot permanently add the result in the moment.  But
 272              we can provide the result as is.  Store the data in some
 273              temporary memory.  */
 274           dataset = (struct dataset *) alloca (total + req->key_len);
 275
 276           /* We cannot add this record to the permanent database.  */
 277           alloca_used = true;
 278         }
 279
 280       dataset->head.allocsize = total + req->key_len;
 281       dataset->head.recsize = total - offsetof (struct dataset, resp);
 282       dataset->head.notfound = false;
 283       dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
 284       dataset->head.usable = true;
 285
 286       /* Compute the timeout time.  */
 287       dataset->head.timeout = time (NULL) + db->postimeout;
 288
 289       dataset->resp.version = NSCD_VERSION;
 290       dataset->resp.found = 1;
 291       dataset->resp.ngrps = start;
 292
 293       char *cp = dataset->strdata;
 294
 295       /* Copy the GID values.  If the size of the types match this is
 296          very simple.  */
 297       if (sizeof (gid_t) == sizeof (int32_t))
 298         cp = mempcpy (cp, groups, start * sizeof (gid_t));
 299       else
 300         {
 301           gid_t *gcp = (gid_t *) cp;
 302
 303           for (int i = 0; i < start; ++i)
 304             *gcp++ = groups[i];
 305
 306           cp = (char *) gcp;
 307         }
 308
 309       /* Finally the user name.  */
 310       memcpy (cp, key, req->key_len);
 311
 312       /* Now we can determine whether on refill we have to create a new
 313          record or not.  */
 314       if (he != NULL)
 315         {
 316           assert (fd == -1);
 317
 318           if (total + req->key_len == dh->allocsize
 319               && total - offsetof (struct dataset, resp) == dh->recsize
 320               && memcmp (&dataset->resp, dh->data,
 321                          dh->allocsize - offsetof (struct dataset, resp)) == 0)
 322             {
 323               /* The data has not changed.  We will just bump the
 324                  timeout value.  Note that the new record has been
 325                  allocated on the stack and need not be freed.  */
 326               dh->timeout = dataset->head.timeout;
 327               ++dh->nreloads;
 328             }
 329           else
 330             {
 331               /* We have to create a new record.  Just allocate
 332                  appropriate memory and copy it.  */
 333               struct dataset *newp
 334                 = (struct dataset *) mempool_alloc (db, total + req->key_len,
 335                                                     IDX_result_data);
 336               if (newp != NULL)
 337                 {
 338                   /* Adjust pointer into the memory block.  */
 339                   cp = (char *) newp + (cp - (char *) dataset);
 340
 341                   dataset = memcpy (newp, dataset, total + req->key_len);
 342                   alloca_used = false;
 343                 }
 344               else
 345                 ++db->head->addfailed;
 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->resp - (char *) db->head
 364                       + total
 365                       <= (sizeof (struct database_pers_head)
 366                           + db->head->module * sizeof (ref_t)
 367                           + db->head->data_size));
 368               written = sendfileall (fd, db->wr_fd,
 369                                      (char *) &dataset->resp
 370                                      - (char *) db->head, total);
 371 # ifndef __ASSUME_SENDFILE
 372               if (written == -1 && errno == ENOSYS)
 373                 goto use_write;
 374 # endif
 375             }
 376           else
 377 # ifndef __ASSUME_SENDFILE
 378           use_write:
 379 # endif
 380 #endif
 381             written = writeall (fd, &dataset->resp, total);
 382         }
 383
 384
 385       /* Add the record to the database.  But only if it has not been
 386          stored on the stack.  */
 387       if (! alloca_used)
 388         {
 389           /* If necessary, we also propagate the data to disk.  */
 390           if (db->persistent)
 391             {
 392               // XXX async OK?
 393               uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 394               msync ((void *) pval,
 395                      ((uintptr_t) dataset & pagesize_m1) + total +
 396                      req->key_len, MS_ASYNC);
 397             }
 398
 399           /* Now get the lock to safely insert the records.  */
 400           pthread_rwlock_rdlock (&db->lock);
 401
 402           if (cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
 403                          db, uid) < 0)
 404             /* Could not allocate memory.  Make sure the data gets
 405                discarded.  */
 406             dataset->head.usable = false;
 407
 408           pthread_rwlock_unlock (&db->lock);
 409         }
 410     }
 411
 412   free (groups);
 413
 414   if (__builtin_expect (written != total, 0) && debug_level > 0)
 415     {
 416       char buf[256];
 417       dbg_log (_("short write in %s: %s"), __FUNCTION__,
 418                strerror_r (errno, buf, sizeof (buf)));
 419     }
 420 }
 421
 422
 423 void
 424 addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
 425                uid_t uid)
 426 {
 427   addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
 428 }
 429
 430
 431 void
 432 readdinitgroups (struct database_dyn *db, struct hashentry *he,
 433                  struct datahead *dh)
 434 {
 435   request_header req =
 436     {
 437       .type = INITGROUPS,
 438       .key_len = he->len
 439     };
 440
 441   addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
 442 }