source4/dsdb/samdb/ldb_modules/acl_read.c

   1 /*
   2   ldb database library
   3
   4   Copyright (C) Simo Sorce 2006-2008
   5   Copyright (C) Nadezhda Ivanova 2010
   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  *  Name: ldb
  23  *
  24  *  Component: ldb ACL Read module
  25  *
  26  *  Description: Module that performs authorisation access checks on read requests
  27  *               Only DACL checks implemented at this point
  28  *
  29  *  Author: Nadezhda Ivanova
  30  */
  31
  32 #include "includes.h"
  33 #include "ldb_module.h"
  34 #include "auth/auth.h"
  35 #include "libcli/security/security.h"
  36 #include "dsdb/samdb/samdb.h"
  37 #include "librpc/gen_ndr/ndr_security.h"
  38 #include "param/param.h"
  39 #include "dsdb/samdb/ldb_modules/util.h"
  40
  41
  42 struct aclread_context {
  43         struct ldb_module *module;
  44         struct ldb_request *req;
  45         const char * const *attrs;
  46         const struct dsdb_schema *schema;
  47         bool sd;
  48         bool instance_type;
  49         bool object_sid;
  50 };
  51
  52 struct aclread_private {
  53         bool enabled;
  54 };
  55
  56 static int aclread_callback(struct ldb_request *req, struct ldb_reply *ares)
  57 {
  58          struct ldb_context *ldb;
  59          struct aclread_context *ac;
  60          int ret;
  61          unsigned int i;
  62          struct security_descriptor *sd;
  63          struct dom_sid *sid = NULL;
  64          TALLOC_CTX *tmp_ctx;
  65          uint32_t instanceType;
  66
  67          ac = talloc_get_type(req->context, struct aclread_context);
  68          ldb = ldb_module_get_ctx(ac->module);
  69          if (!ares) {
  70                  return ldb_module_done(ac->req, NULL, NULL, LDB_ERR_OPERATIONS_ERROR );
  71          }
  72          if (ares->error != LDB_SUCCESS) {
  73                  return ldb_module_done(ac->req, ares->controls,
  74                                         ares->response, ares->error);
  75          }
  76          tmp_ctx = talloc_new(ac);
  77          switch (ares->type) {
  78          case LDB_REPLY_ENTRY:
  79                  ret = dsdb_get_sd_from_ldb_message(ldb, tmp_ctx, ares->message, &sd);
  80                  if (ret != LDB_SUCCESS) {
  81                          DEBUG(10, ("acl_read: cannot get descriptor\n"));
  82                          ret = LDB_ERR_OPERATIONS_ERROR;
  83                          goto fail;
  84                  }
  85                  sid = samdb_result_dom_sid(tmp_ctx, ares->message, "objectSid");
  86                  /* get the object instance type */
  87                  instanceType = ldb_msg_find_attr_as_uint(ares->message,
  88                                                          "instanceType", 0);
  89                  if (!ldb_dn_is_null(ares->message->dn) && !(instanceType & INSTANCE_TYPE_IS_NC_HEAD))
  90                  {
  91                         /* the object has a parent, so we have to check for visibility */
  92                         struct ldb_dn *parent_dn = ldb_dn_get_parent(tmp_ctx, ares->message->dn);
  93                         ret = dsdb_module_check_access_on_dn(ac->module,
  94                                                              tmp_ctx,
  95                                                              parent_dn,
  96                                                              SEC_ADS_LIST,
  97                                                              NULL);
  98                         if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
  99                                 talloc_free(tmp_ctx);
 100                                 return LDB_SUCCESS;
 101                         } else if (ret != LDB_SUCCESS) {
 102                                 goto fail;
 103                         }
 104                  }
 105                  /* for every element in the message check RP */
 106                  i = 0;
 107                  while (i < ares->message->num_elements) {
 108                          const struct dsdb_attribute *attr;
 109                          attr =  dsdb_attribute_by_lDAPDisplayName(ac->schema,
 110                                                                    ares->message->elements[i].name);
 111                          if (!attr) {
 112                                  DEBUG(2, ("acl_read: cannot find attribute %s in schema\n",
 113                                            ares->message->elements[i].name));
 114                                  ret = LDB_ERR_OPERATIONS_ERROR;
 115                                  goto fail;
 116                          }
 117                          /* nTSecurityDescriptor is a special case */
 118                          if (ldb_attr_cmp("nTSecurityDescriptor",
 119                                           ares->message->elements[i].name) == 0) {
 120                                  if (ac->sd) {
 121                                          ldb_msg_remove_attr(ares->message, ares->message->elements[i].name);
 122                                          ret = LDB_SUCCESS;
 123                                  }
 124                                  ret = acl_check_access_on_attribute(ac->module,
 125                                                                      tmp_ctx,
 126                                                                      sd,
 127                                                                      sid,
 128                                                                      SEC_FLAG_SYSTEM_SECURITY|SEC_STD_READ_CONTROL,
 129                                                                      attr);
 130                          } else {
 131                                  ret = acl_check_access_on_attribute(ac->module,
 132                                                                      tmp_ctx,
 133                                                                      sd,
 134                                                                      sid,
 135                                                                      SEC_ADS_READ_PROP,
 136                                                                      attr);
 137                          }
 138                          if (ret == LDB_SUCCESS) {
 139                                  i++;
 140                          } else if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
 141                                  /* do not return this entry if attribute is
 142                                             part of the search filter */
 143                                  if (dsdb_attr_in_parse_tree(ac->req->op.search.tree,
 144                                                              ares->message->elements[i].name)) {
 145                                          talloc_free(tmp_ctx);
 146                                          return LDB_SUCCESS;
 147                                  }
 148                                  ldb_msg_remove_attr(ares->message, ares->message->elements[i].name);
 149                          } else {
 150                                  goto fail;
 151                          }
 152                  }
 153                  if (ac->instance_type) {
 154                          ldb_msg_remove_attr(ares->message, "instanceType");
 155                  }
 156                  if (ac->object_sid) {
 157                          ldb_msg_remove_attr(ares->message, "objectSid");
 158                  }
 159                  talloc_free(tmp_ctx);
 160                  return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 161          case LDB_REPLY_REFERRAL:
 162                  return ldb_module_send_referral(ac->req, ares->referral);
 163          case LDB_REPLY_DONE:
 164                  return ldb_module_done(ac->req, ares->controls,
 165                                         ares->response, LDB_SUCCESS);
 166
 167          }
 168          return LDB_SUCCESS;
 169 fail:
 170          talloc_free(tmp_ctx);
 171          return ldb_module_done(ac->req, NULL, NULL, ret);
 172 }
 173
 174
 175 static int aclread_search(struct ldb_module *module, struct ldb_request *req)
 176 {
 177         struct ldb_context *ldb;
 178         int ret;
 179         struct aclread_context *ac;
 180         struct ldb_request *down_req;
 181         struct ldb_control *as_system = ldb_request_get_control(req, LDB_CONTROL_AS_SYSTEM_OID);
 182         struct ldb_result *res;
 183         struct aclread_private *p;
 184         bool is_untrusted = ldb_req_is_untrusted(req);
 185         const char * const *attrs = NULL;
 186         uint32_t instanceType;
 187         static const char *acl_attrs[] = {
 188                  "instanceType",
 189                  NULL
 190         };
 191
 192         ldb = ldb_module_get_ctx(module);
 193         p = talloc_get_type(ldb_module_get_private(module), struct aclread_private);
 194
 195         /* skip access checks if we are system or system control is supplied
 196          * or this is not LDAP server request */
 197         if (!p || !p->enabled ||
 198             dsdb_module_am_system(module)
 199             || as_system || !is_untrusted) {
 200                 return ldb_next_request(module, req);
 201         }
 202         /* no checks on special dn */
 203         if (ldb_dn_is_special(req->op.search.base)) {
 204                 return ldb_next_request(module, req);
 205         }
 206
 207         /* check accessibility of base */
 208         if (!ldb_dn_is_null(req->op.search.base)) {
 209                 ret = dsdb_module_search_dn(module, req, &res, req->op.search.base,
 210                                             acl_attrs,
 211                                             DSDB_FLAG_NEXT_MODULE |
 212                                             DSDB_SEARCH_SHOW_DELETED);
 213                 if (ret != LDB_SUCCESS) {
 214                         return ldb_error(ldb, ret,
 215                                          "acl_read: Error retrieving instanceType for base.");
 216                 }
 217                 instanceType = ldb_msg_find_attr_as_uint(res->msgs[0],
 218                                                          "instanceType", 0);
 219                 if (instanceType != 0 && !(instanceType & INSTANCE_TYPE_IS_NC_HEAD))
 220                 {
 221                         /* the object has a parent, so we have to check for visibility */
 222                         struct ldb_dn *parent_dn = ldb_dn_get_parent(req, req->op.search.base);
 223                         ret = dsdb_module_check_access_on_dn(module,
 224                                                              req,
 225                                                              parent_dn,
 226                                                              SEC_ADS_LIST,
 227                                                              NULL);
 228                         if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
 229                                 return ldb_module_done(req, NULL, NULL, LDB_ERR_NO_SUCH_OBJECT);
 230                         } else if (ret != LDB_SUCCESS) {
 231                                 return ldb_module_done(req, NULL, NULL, ret);
 232                         }
 233                 }
 234         }
 235         ac = talloc_zero(req, struct aclread_context);
 236         if (ac == NULL) {
 237                 return ldb_oom(ldb);
 238         }
 239         ac->module = module;
 240         ac->req = req;
 241         ac->schema = dsdb_get_schema(ldb, req);
 242         if (!ac->schema) {
 243                 return ldb_operr(ldb);
 244         }
 245         ac->sd = !(ldb_attr_in_list(req->op.search.attrs, "nTSecurityDescriptor"));
 246         if (req->op.search.attrs && !ldb_attr_in_list(req->op.search.attrs, "*")) {
 247                 if (!ldb_attr_in_list(req->op.search.attrs, "instanceType")) {
 248                         ac->instance_type = true;
 249                         attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "instanceType");
 250                 } else {
 251                         attrs = req->op.search.attrs;
 252                 }
 253                 if (!ldb_attr_in_list(req->op.search.attrs, "objectSid")) {
 254                         ac->object_sid = true;
 255                         attrs = ldb_attr_list_copy_add(ac, attrs, "objectSid");
 256                 }
 257         }
 258
 259         if (ac->sd) {
 260                 /* avoid replacing all attributes with nTSecurityDescriptor
 261                  * if attribute list is empty */
 262                 if (!attrs) {
 263                         attrs = ldb_attr_list_copy_add(ac, attrs, "*");
 264                 }
 265                 attrs = ldb_attr_list_copy_add(ac, attrs, "nTSecurityDescriptor");
 266         }
 267         ac->attrs = req->op.search.attrs;
 268         ret = ldb_build_search_req_ex(&down_req,
 269                                       ldb, ac,
 270                                       req->op.search.base,
 271                                       req->op.search.scope,
 272                                       req->op.search.tree,
 273                                       attrs,
 274                                       req->controls,
 275                                       ac, aclread_callback,
 276                                       req);
 277
 278         if (ret != LDB_SUCCESS) {
 279                 return LDB_ERR_OPERATIONS_ERROR;
 280         }
 281
 282         return ldb_next_request(module, down_req);
 283 }
 284
 285 static int aclread_init(struct ldb_module *module)
 286 {
 287         struct ldb_context *ldb = ldb_module_get_ctx(module);
 288         struct aclread_private *p = talloc_zero(module, struct aclread_private);
 289         if (p == NULL) {
 290                 return ldb_module_oom(module);
 291         }
 292         p->enabled = lpcfg_parm_bool(ldb_get_opaque(ldb, "loadparm"), NULL, "acl", "search", false);
 293         ldb_module_set_private(module, p);
 294         return ldb_next_init(module);
 295 }
 296
 297 static const struct ldb_module_ops ldb_aclread_module_ops = {
 298         .name              = "aclread",
 299         .search            = aclread_search,
 300         .init_context      = aclread_init
 301 };
 302
 303 int ldb_aclread_module_init(const char *version)
 304 {
 305         LDB_MODULE_CHECK_VERSION(version);
 306         return ldb_register_module(&ldb_aclread_module_ops);
 307 }