nscd/initgrcache.c

   1 /* Cache handling for host lookup.
   2    Copyright (C) 2004, 2005, 2006, 2008, 2009 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 *const 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                                    1);
 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               (void) cache_add (req->type, key_copy, req->key_len,
 231                                 &dataset->head, true, db, uid, he == NULL);
 232
 233               pthread_rwlock_unlock (&db->lock);
 234
 235               /* Mark the old entry as obsolete.  */
 236               if (dh != NULL)
 237                 dh->usable = false;
 238             }
 239         }
 240     }
 241   else
 242     {
 243
 244       written = total = (offsetof (struct dataset, strdata)
 245                          + start * sizeof (int32_t));
 246
 247       /* If we refill the cache, first assume the reconrd did not
 248          change.  Allocate memory on the cache since it is likely
 249          discarded anyway.  If it turns out to be necessary to have a
 250          new record we can still allocate real memory.  */
 251       bool alloca_used = false;
 252       dataset = NULL;
 253
 254       if (he == NULL)
 255         dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
 256                                                     1);
 257
 258       if (dataset == NULL)
 259         {
 260           /* We cannot permanently add the result in the moment.  But
 261              we can provide the result as is.  Store the data in some
 262              temporary memory.  */
 263           dataset = (struct dataset *) alloca (total + req->key_len);
 264
 265           /* We cannot add this record to the permanent database.  */
 266           alloca_used = true;
 267         }
 268
 269       dataset->head.allocsize = total + req->key_len;
 270       dataset->head.recsize = total - offsetof (struct dataset, resp);
 271       dataset->head.notfound = false;
 272       dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
 273       dataset->head.usable = true;
 274
 275       /* Compute the timeout time.  */
 276       dataset->head.timeout = time (NULL) + db->postimeout;
 277
 278       dataset->resp.version = NSCD_VERSION;
 279       dataset->resp.found = 1;
 280       dataset->resp.ngrps = start;
 281
 282       char *cp = dataset->strdata;
 283
 284       /* Copy the GID values.  If the size of the types match this is
 285          very simple.  */
 286       if (sizeof (gid_t) == sizeof (int32_t))
 287         cp = mempcpy (cp, groups, start * sizeof (gid_t));
 288       else
 289         {
 290           gid_t *gcp = (gid_t *) cp;
 291
 292           for (int i = 0; i < start; ++i)
 293             *gcp++ = groups[i];
 294
 295           cp = (char *) gcp;
 296         }
 297
 298       /* Finally the user name.  */
 299       memcpy (cp, key, req->key_len);
 300
 301       assert (cp == dataset->strdata + total - offsetof (struct dataset,
 302                                                          strdata));
 303
 304       /* Now we can determine whether on refill we have to create a new
 305          record or not.  */
 306       if (he != NULL)
 307         {
 308           assert (fd == -1);
 309
 310           if (total + req->key_len == dh->allocsize
 311               && total - offsetof (struct dataset, resp) == dh->recsize
 312               && memcmp (&dataset->resp, dh->data,
 313                          dh->allocsize - offsetof (struct dataset, resp)) == 0)
 314             {
 315               /* The data has not changed.  We will just bump the
 316                  timeout value.  Note that the new record has been
 317                  allocated on the stack and need not be freed.  */
 318               dh->timeout = dataset->head.timeout;
 319               ++dh->nreloads;
 320             }
 321           else
 322             {
 323               /* We have to create a new record.  Just allocate
 324                  appropriate memory and copy it.  */
 325               struct dataset *newp
 326                 = (struct dataset *) mempool_alloc (db, total + req->key_len,
 327                                                     1);
 328               if (newp != NULL)
 329                 {
 330                   /* Adjust pointer into the memory block.  */
 331                   cp = (char *) newp + (cp - (char *) dataset);
 332
 333                   dataset = memcpy (newp, dataset, total + req->key_len);
 334                   alloca_used = false;
 335                 }
 336
 337               /* Mark the old record as obsolete.  */
 338               dh->usable = false;
 339             }
 340         }
 341       else
 342         {
 343           /* We write the dataset before inserting it to the database
 344              since while inserting this thread might block and so would
 345              unnecessarily let the receiver wait.  */
 346           assert (fd != -1);
 347
 348 #ifdef HAVE_SENDFILE
 349           if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
 350             {
 351               assert (db->wr_fd != -1);
 352               assert ((char *) &dataset->resp > (char *) db->data);
 353               assert ((char *) &dataset->resp - (char *) db->head
 354                       + total
 355                       <= (sizeof (struct database_pers_head)
 356                           + db->head->module * sizeof (ref_t)
 357                           + db->head->data_size));
 358               written = sendfileall (fd, db->wr_fd,
 359                                      (char *) &dataset->resp
 360                                      - (char *) db->head, total);
 361 # ifndef __ASSUME_SENDFILE
 362               if (written == -1 && errno == ENOSYS)
 363                 goto use_write;
 364 # endif
 365             }
 366           else
 367 # ifndef __ASSUME_SENDFILE
 368           use_write:
 369 # endif
 370 #endif
 371             written = writeall (fd, &dataset->resp, total);
 372         }
 373
 374
 375       /* Add the record to the database.  But only if it has not been
 376          stored on the stack.  */
 377       if (! alloca_used)
 378         {
 379           /* If necessary, we also propagate the data to disk.  */
 380           if (db->persistent)
 381             {
 382               // XXX async OK?
 383               uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
 384               msync ((void *) pval,
 385                      ((uintptr_t) dataset & pagesize_m1) + total +
 386                      req->key_len, MS_ASYNC);
 387             }
 388
 389           (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true,
 390                             db, uid, he == NULL);
 391
 392           pthread_rwlock_unlock (&db->lock);
 393         }
 394     }
 395
 396   free (groups);
 397
 398   if (__builtin_expect (written != total, 0) && debug_level > 0)
 399     {
 400       char buf[256];
 401       dbg_log (_("short write in %s: %s"), __FUNCTION__,
 402                strerror_r (errno, buf, sizeof (buf)));
 403     }
 404 }
 405
 406
 407 void
 408 addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key,
 409                uid_t uid)
 410 {
 411   addinitgroupsX (db, fd, req, key, uid, NULL, NULL);
 412 }
 413
 414
 415 void
 416 readdinitgroups (struct database_dyn *db, struct hashentry *he,
 417                  struct datahead *dh)
 418 {
 419   request_header req =
 420     {
 421       .type = INITGROUPS,
 422       .key_len = he->len
 423     };
 424
 425   addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh);
 426 }