source/lib/system_smbd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    system call wrapper interface.
   4    Copyright (C) Andrew Tridgell 2002
   5    Copyright (C) Andrew Barteltt 2002
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /*
  23    This file may assume linkage with smbd - for things like become_root()
  24    etc.
  25 */
  26
  27 #include "includes.h"
  28
  29 #ifndef HAVE_GETGROUPLIST
  30 /*
  31   This is a *much* faster way of getting the list of groups for a user
  32   without changing the current supplemenrary group list. The old
  33   method used getgrent() which could take 20 minutes on a really big
  34   network with hundeds of thousands of groups and users. The new method
  35   takes a couple of seconds.
  36
  37   NOTE!! this function only works if it is called as root!
  38   */
  39 static int getgrouplist_internals(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
  40 {
  41         gid_t *gids_saved;
  42         int ret, ngrp_saved;
  43
  44         if (non_root_mode()) {
  45                 *grpcnt = 0;
  46                 return 0;
  47         }
  48
  49         /* work out how many groups we need to save */
  50         ngrp_saved = getgroups(0, NULL);
  51         if (ngrp_saved == -1) {
  52                 /* this shouldn't happen */
  53                 return -1;
  54         }
  55
  56         gids_saved = (gid_t *)malloc(sizeof(gid_t) * (ngrp_saved+1));
  57         if (!gids_saved) {
  58                 errno = ENOMEM;
  59                 return -1;
  60         }
  61
  62         ngrp_saved = getgroups(ngrp_saved, gids_saved);
  63         if (ngrp_saved == -1) {
  64                 SAFE_FREE(gids_saved);
  65                 /* very strange! */
  66                 return -1;
  67         }
  68
  69         if (initgroups(user, gid) != 0) {
  70                 DEBUG(0, ("getgrouplist_internals: initgroups() failed!\n"));
  71                 SAFE_FREE(gids_saved);
  72                 return -1;
  73         }
  74
  75         /* this must be done to cope with systems that put the current egid in the
  76            return from getgroups() */
  77         save_re_gid();
  78         set_effective_gid(gid);
  79         setgid(gid);
  80
  81         ret = getgroups(*grpcnt, groups);
  82         if (ret >= 0) {
  83                 *grpcnt = ret;
  84         }
  85
  86         restore_re_gid();
  87
  88         if (setgroups(ngrp_saved, gids_saved) != 0) {
  89                 /* yikes! */
  90                 DEBUG(0,("ERROR: getgrouplist: failed to reset group list!\n"));
  91                 smb_panic("getgrouplist: failed to reset group list!\n");
  92                 free(gids_saved);
  93                 return -1;
  94         }
  95
  96         free(gids_saved);
  97         return ret;
  98 }
  99 #endif
 100
 101 int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
 102 {
 103 #ifdef HAVE_GETGROUPLIST
 104         return getgrouplist(user, gid, groups, grpcnt);
 105 #else
 106         int retval;
 107         become_root();
 108         retval = getgrouplist_internals(user, gid, groups, grpcnt);
 109         unbecome_root();
 110         return retval;
 111 #endif
 112 }