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 3 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, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 /*
  22    This file may assume linkage with smbd - for things like become_root()
  23    etc.
  24 */
  25
  26 #include "includes.h"
  27
  28 #ifndef HAVE_GETGROUPLIST
  29
  30 /*
  31   This is a *much* faster way of getting the list of groups for a user
  32   without changing the current supplementary 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
  40 static int getgrouplist_internals(const char *user, gid_t gid, gid_t *groups,
  41                                   int *grpcnt)
  42 {
  43         gid_t *gids_saved;
  44         int ret, ngrp_saved, num_gids;
  45
  46         if (non_root_mode()) {
  47                 *grpcnt = 0;
  48                 return 0;
  49         }
  50
  51         /* work out how many groups we need to save */
  52         ngrp_saved = getgroups(0, NULL);
  53         if (ngrp_saved == -1) {
  54                 /* this shouldn't happen */
  55                 return -1;
  56         }
  57
  58         gids_saved = SMB_MALLOC_ARRAY(gid_t, ngrp_saved+1);
  59         if (!gids_saved) {
  60                 errno = ENOMEM;
  61                 return -1;
  62         }
  63
  64         ngrp_saved = getgroups(ngrp_saved, gids_saved);
  65         if (ngrp_saved == -1) {
  66                 SAFE_FREE(gids_saved);
  67                 /* very strange! */
  68                 return -1;
  69         }
  70
  71         if (initgroups(user, gid) != 0) {
  72                 DEBUG(0, ("getgrouplist_internals: initgroups() failed!\n"));
  73                 SAFE_FREE(gids_saved);
  74                 return -1;
  75         }
  76
  77         /* this must be done to cope with systems that put the current egid in the
  78            return from getgroups() */
  79         save_re_gid();
  80         set_effective_gid(gid);
  81         setgid(gid);
  82
  83         num_gids = getgroups(0, NULL);
  84         if (num_gids == -1) {
  85                 SAFE_FREE(gids_saved);
  86                 /* very strange! */
  87                 return -1;
  88         }
  89
  90         if (num_gids + 1 > *grpcnt) {
  91                 *grpcnt = num_gids + 1;
  92                 ret = -1;
  93         } else {
  94                 ret = getgroups(*grpcnt - 1, &groups[1]);
  95                 if (ret < 0) {
  96                         SAFE_FREE(gids_saved);
  97                         /* very strange! */
  98                         return -1;
  99                 }
 100                 groups[0] = gid;
 101                 *grpcnt = ret + 1;
 102         }
 103
 104         restore_re_gid();
 105
 106         if (sys_setgroups(gid, ngrp_saved, gids_saved) != 0) {
 107                 /* yikes! */
 108                 DEBUG(0,("ERROR: getgrouplist: failed to reset group list!\n"));
 109                 smb_panic("getgrouplist: failed to reset group list!");
 110         }
 111
 112         free(gids_saved);
 113         return ret;
 114 }
 115 #endif
 116
 117 static int sys_getgrouplist(const char *user, gid_t gid, gid_t *groups, int *grpcnt)
 118 {
 119         int retval;
 120         bool winbind_env;
 121
 122         DEBUG(10,("sys_getgrouplist: user [%s]\n", user));
 123
 124         /* This is only ever called for Unix users, remote memberships are
 125          * always determined by the info3 coming back from auth3 or the
 126          * PAC. */
 127         winbind_env = winbind_env_set();
 128         (void)winbind_off();
 129
 130 #ifdef HAVE_GETGROUPLIST
 131         retval = getgrouplist(user, gid, groups, grpcnt);
 132 #else
 133         become_root();
 134         retval = getgrouplist_internals(user, gid, groups, grpcnt);
 135         unbecome_root();
 136 #endif
 137
 138         /* allow winbindd lookups, but only if they were not already disabled */
 139         if (!winbind_env) {
 140                 (void)winbind_on();
 141         }
 142
 143         return retval;
 144 }
 145
 146 bool getgroups_unix_user(TALLOC_CTX *mem_ctx, const char *user,
 147                          gid_t primary_gid,
 148                          gid_t **ret_groups, size_t *p_ngroups)
 149 {
 150         size_t ngrp;
 151         int max_grp;
 152         gid_t *temp_groups;
 153         gid_t *groups;
 154         int i;
 155
 156         max_grp = MIN(32, groups_max());
 157         temp_groups = SMB_MALLOC_ARRAY(gid_t, max_grp);
 158         if (! temp_groups) {
 159                 return False;
 160         }
 161
 162         if (sys_getgrouplist(user, primary_gid, temp_groups, &max_grp) == -1) {
 163                 temp_groups = SMB_REALLOC_ARRAY(temp_groups, gid_t, max_grp);
 164                 if (!temp_groups) {
 165                         return False;
 166                 }
 167
 168                 if (sys_getgrouplist(user, primary_gid,
 169                                      temp_groups, &max_grp) == -1) {
 170                         DEBUG(0, ("get_user_groups: failed to get the unix "
 171                                   "group list\n"));
 172                         SAFE_FREE(temp_groups);
 173                         return False;
 174                 }
 175         }
 176
 177         ngrp = 0;
 178         groups = NULL;
 179
 180         /* Add in primary group first */
 181         if (!add_gid_to_array_unique(mem_ctx, primary_gid, &groups, &ngrp)) {
 182                 SAFE_FREE(temp_groups);
 183                 return False;
 184         }
 185
 186         for (i=0; i<max_grp; i++) {
 187                 if (!add_gid_to_array_unique(mem_ctx, temp_groups[i],
 188                                         &groups, &ngrp)) {
 189                         SAFE_FREE(temp_groups);
 190                         return False;
 191                 }
 192         }
 193
 194         *p_ngroups = ngrp;
 195         *ret_groups = groups;
 196         SAFE_FREE(temp_groups);
 197         return True;
 198 }