nscd/nscd_initgroups.c

   1 /* Copyright (C) 2004, 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <not-cancel.h>
  27
  28 #include "nscd-client.h"
  29 #include "nscd_proto.h"
  30
  31
  32 /* We use the same mapping as in nscd_getgr.   */
  33 libc_locked_map_ptr (extern, __gr_map_handle) attribute_hidden;
  34
  35
  36 int
  37 __nscd_getgrouplist (const char *user, gid_t group, long int *size,
  38                      gid_t **groupsp, long int limit)
  39 {
  40   size_t userlen = strlen (user) + 1;
  41   int gc_cycle;
  42   int nretries = 0;
  43
  44   /* If the mapping is available, try to search there instead of
  45      communicating with the nscd.  */
  46   struct mapped_database *mapped;
  47   mapped = __nscd_get_map_ref (GETFDGR, "group", &__gr_map_handle, &gc_cycle);
  48
  49  retry:;
  50   char *respdata = NULL;
  51   int retval = -1;
  52   int sock = -1;
  53   initgr_response_header initgr_resp;
  54
  55   if (mapped != NO_MAPPING)
  56     {
  57       struct datahead *found = __nscd_cache_search (INITGROUPS, user,
  58                                                     userlen, mapped,
  59                                                     sizeof initgr_resp);
  60       if (found != NULL)
  61         {
  62           respdata = (char *) (&found->data[0].initgrdata + 1);
  63           initgr_resp = found->data[0].initgrdata;
  64           char *recend = (char *) found->data + found->recsize;
  65
  66           /* Now check if we can trust initgr_resp fields.  If GC is
  67              in progress, it can contain anything.  */
  68           if (mapped->head->gc_cycle != gc_cycle)
  69             {
  70               retval = -2;
  71               goto out;
  72             }
  73
  74           if (respdata + initgr_resp.ngrps * sizeof (int32_t) > recend)
  75             goto out;
  76         }
  77     }
  78
  79   /* If we do not have the cache mapped, try to get the data over the
  80      socket.  */
  81   if (respdata == NULL)
  82     {
  83       sock = __nscd_open_socket (user, userlen, INITGROUPS, &initgr_resp,
  84                                  sizeof (initgr_resp));
  85       if (sock == -1)
  86         {
  87           /* nscd not running or wrong version.  */
  88           __nss_not_use_nscd_group = 1;
  89           goto out;
  90         }
  91     }
  92
  93   if (initgr_resp.found == 1)
  94     {
  95       /* The following code assumes that gid_t and int32_t are the
  96          same size.  This is the case for al existing implementation.
  97          If this should change some code needs to be added which
  98          doesn't use memcpy but instead copies each array element one
  99          by one.  */
 100       assert (sizeof (int32_t) == sizeof (gid_t));
 101       assert (initgr_resp.ngrps >= 0);
 102
 103       /* Make sure we have enough room.  We always count GROUP in even
 104          though we might not end up adding it.  */
 105       if (*size < initgr_resp.ngrps + 1)
 106         {
 107           gid_t *newp = realloc (*groupsp,
 108                                  (initgr_resp.ngrps + 1) * sizeof (gid_t));
 109           if (newp == NULL)
 110             /* We cannot increase the buffer size.  */
 111             goto out_close;
 112
 113           *groupsp = newp;
 114           *size = initgr_resp.ngrps + 1;
 115         }
 116
 117       if (respdata == NULL)
 118         {
 119           /* Read the data from the socket.  */
 120           if ((size_t) __readall (sock, *groupsp, initgr_resp.ngrps
 121                                                   * sizeof (gid_t))
 122               == initgr_resp.ngrps * sizeof (gid_t))
 123             retval = initgr_resp.ngrps;
 124         }
 125       else
 126         {
 127           /* Just copy the data.  */
 128           retval = initgr_resp.ngrps;
 129           memcpy (*groupsp, respdata, retval * sizeof (gid_t));
 130         }
 131     }
 132   else
 133     {
 134       if (__builtin_expect (initgr_resp.found == -1, 0))
 135         {
 136           /* The daemon does not cache this database.  */
 137           __nss_not_use_nscd_group = 1;
 138           goto out_close;
 139         }
 140
 141       /* No group found yet.   */
 142       retval = 0;
 143
 144       assert (*size >= 1);
 145     }
 146
 147   /* Check whether GROUP is part of the mix.  If not, add it.  */
 148   if (retval >= 0)
 149     {
 150       int cnt;
 151       for (cnt = 0; cnt < retval; ++cnt)
 152         if ((*groupsp)[cnt] == group)
 153           break;
 154
 155       if (cnt == retval)
 156         (*groupsp)[retval++] = group;
 157     }
 158
 159  out_close:
 160   if (sock != -1)
 161     close_not_cancel_no_status (sock);
 162  out:
 163   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 164     {
 165       /* When we come here this means there has been a GC cycle while we
 166          were looking for the data.  This means the data might have been
 167          inconsistent.  Retry if possible.  */
 168       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 169         {
 170           /* nscd is just running gc now.  Disable using the mapping.  */
 171           if (atomic_decrement_val (&mapped->counter) == 0)
 172             __nscd_unmap (mapped);
 173           mapped = NO_MAPPING;
 174         }
 175
 176       if (retval != -1)
 177         goto retry;
 178     }
 179
 180   return retval;
 181 }