source4/dsdb/common/dsdb_access.c

   1 /*
   2   ldb database library
   3
   4   Copyright (C) Nadezhda Ivanova 2010
   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 by
   8   the Free Software Foundation; either version 3 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, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21  *  Name: dsdb_access
  22  *
  23  *  Description: utility functions for access checking on objects
  24  *
  25  *  Authors: Nadezhda Ivanova
  26  */
  27
  28 #include "includes.h"
  29 #include "ldb.h"
  30 #include "ldb_module.h"
  31 #include "ldb_errors.h"
  32 #include "libcli/security/security.h"
  33 #include "librpc/gen_ndr/ndr_security.h"
  34 #include "libcli/ldap/ldap_ndr.h"
  35 #include "param/param.h"
  36 #include "auth/auth.h"
  37 #include "dsdb/samdb/samdb.h"
  38 #include "dsdb/common/util.h"
  39
  40 void dsdb_acl_debug(struct security_descriptor *sd,
  41                       struct security_token *token,
  42                       struct ldb_dn *dn,
  43                       bool denied,
  44                       int level)
  45 {
  46         if (denied) {
  47                 DEBUG(level, ("Access on %s denied", ldb_dn_get_linearized(dn)));
  48         } else {
  49                 DEBUG(level, ("Access on %s granted", ldb_dn_get_linearized(dn)));
  50         }
  51
  52         DEBUG(level,("Security context: %s\n",
  53                      ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_token,"", token)));
  54         DEBUG(level,("Security descriptor: %s\n",
  55                      ndr_print_struct_string(0,(ndr_print_fn_t)ndr_print_security_descriptor,"", sd)));
  56 }
  57
  58 int dsdb_get_sd_from_ldb_message(struct ldb_context *ldb,
  59                                  TALLOC_CTX *mem_ctx,
  60                                  struct ldb_message *acl_res,
  61                                  struct security_descriptor **sd)
  62 {
  63         struct ldb_message_element *sd_element;
  64         enum ndr_err_code ndr_err;
  65
  66         sd_element = ldb_msg_find_element(acl_res, "nTSecurityDescriptor");
  67         if (!sd_element) {
  68                 *sd = NULL;
  69                 return LDB_SUCCESS;
  70         }
  71         *sd = talloc(mem_ctx, struct security_descriptor);
  72         if(!*sd) {
  73                 return ldb_oom(ldb);
  74         }
  75         ndr_err = ndr_pull_struct_blob(&sd_element->values[0], *sd, *sd,
  76                                        (ndr_pull_flags_fn_t)ndr_pull_security_descriptor);
  77
  78         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  79                 return ldb_operr(ldb);
  80         }
  81
  82         return LDB_SUCCESS;
  83 }
  84
  85 int dsdb_check_access_on_dn_internal(struct ldb_context *ldb,
  86                                      struct ldb_result *acl_res,
  87                                      TALLOC_CTX *mem_ctx,
  88                                      struct security_token *token,
  89                                      struct ldb_dn *dn,
  90                                      uint32_t access_mask,
  91                                      const struct GUID *guid)
  92 {
  93         struct security_descriptor *sd = NULL;
  94         struct dom_sid *sid = NULL;
  95         struct object_tree *root = NULL;
  96         NTSTATUS status;
  97         uint32_t access_granted;
  98         int ret;
  99
 100         ret = dsdb_get_sd_from_ldb_message(ldb, mem_ctx, acl_res->msgs[0], &sd);
 101         if (ret != LDB_SUCCESS) {
 102                 return ldb_operr(ldb);
 103         }
 104         /* Theoretically we pass the check if the object has no sd */
 105         if (!sd) {
 106                 return LDB_SUCCESS;
 107         }
 108         sid = samdb_result_dom_sid(mem_ctx, acl_res->msgs[0], "objectSid");
 109         if (guid) {
 110                 if (!insert_in_object_tree(mem_ctx, guid, access_mask, NULL,
 111                                            &root)) {
 112                         return ldb_operr(ldb);
 113                 }
 114         }
 115         status = sec_access_check_ds(sd, token,
 116                                      access_mask,
 117                                      &access_granted,
 118                                      root,
 119                                      sid);
 120         if (!NT_STATUS_IS_OK(status)) {
 121                 dsdb_acl_debug(sd,
 122                                token,
 123                                dn,
 124                                true,
 125                                10);
 126                 ldb_asprintf_errstring(ldb,
 127                                        "dsdb_access: Access check failed on %s",
 128                                        ldb_dn_get_linearized(dn));
 129                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 130         }
 131         return LDB_SUCCESS;
 132 }
 133
 134 /* performs an access check from outside the module stack
 135  * given the dn of the object to be checked, the required access
 136  * guid is either the guid of the extended right, or NULL
 137  */
 138
 139 int dsdb_check_access_on_dn(struct ldb_context *ldb,
 140                             TALLOC_CTX *mem_ctx,
 141                             struct ldb_dn *dn,
 142                             struct security_token *token,
 143                             uint32_t access_mask,
 144                             const char *ext_right)
 145 {
 146         int ret;
 147         struct GUID guid;
 148         struct ldb_result *acl_res;
 149         static const char *acl_attrs[] = {
 150                 "nTSecurityDescriptor",
 151                 "objectSid",
 152                 NULL
 153         };
 154
 155         if (ext_right != NULL) {
 156                 NTSTATUS status = GUID_from_string(ext_right, &guid);
 157                 if (!NT_STATUS_IS_OK(status)) {
 158                         return LDB_ERR_OPERATIONS_ERROR;
 159                 }
 160         }
 161
 162         /*
 163          * We need AS_SYSTEM in order to get the nTSecurityDescriptor attribute.
 164          * Also the result of this search not controlled by the client
 165          * nor is the result exposed to the client.
 166          */
 167         ret = dsdb_search_dn(ldb, mem_ctx, &acl_res, dn, acl_attrs,
 168                              DSDB_FLAG_AS_SYSTEM | DSDB_SEARCH_SHOW_RECYCLED);
 169         if (ret != LDB_SUCCESS) {
 170                 DEBUG(10,("access_check: failed to find object %s\n", ldb_dn_get_linearized(dn)));
 171                 return ret;
 172         }
 173
 174         return dsdb_check_access_on_dn_internal(ldb, acl_res,
 175                                                 mem_ctx,
 176                                                 token,
 177                                                 dn,
 178                                                 access_mask,
 179                                                 ext_right ? &guid : NULL);
 180 }
 181