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 };
  48
  49 struct aclread_private {
  50         bool enabled;
  51 };
  52
  53 static int aclread_callback(struct ldb_request *req, struct ldb_reply *ares)
  54 {
  55          struct ldb_context *ldb;
  56          struct aclread_context *ac;
  57          struct ldb_result *acl_res;
  58          struct ldb_message_element *parent;
  59          static const char *acl_attrs[] = {
  60                  "nTSecurityDescriptor",
  61                  "objectSid",
  62                  "parentGUID",
  63                  NULL
  64          };
  65          int ret;
  66          unsigned int i;
  67          struct security_descriptor *sd;
  68          struct dom_sid *sid = NULL;
  69          TALLOC_CTX *tmp_ctx;
  70          ac = talloc_get_type(req->context, struct aclread_context);
  71          ldb = ldb_module_get_ctx(ac->module);
  72          if (!ares) {
  73                  return ldb_module_done(ac->req, NULL, NULL, LDB_ERR_OPERATIONS_ERROR );
  74          }
  75          if (ares->error != LDB_SUCCESS) {
  76                  return ldb_module_done(ac->req, ares->controls,
  77                                         ares->response, ares->error);
  78          }
  79          tmp_ctx = talloc_new(ac);
  80          switch (ares->type) {
  81          case LDB_REPLY_ENTRY:
  82                  ret = dsdb_module_search_dn(ac->module, tmp_ctx, &acl_res, ares->message->dn,
  83                                              acl_attrs,
  84                                              DSDB_FLAG_NEXT_MODULE |
  85                                              DSDB_SEARCH_SHOW_DELETED);
  86                  if (ret != LDB_SUCCESS) {
  87                          goto fail;
  88                  }
  89                  ret = dsdb_get_sd_from_ldb_message(ldb, tmp_ctx, acl_res->msgs[0], &sd);
  90                  if (ret != LDB_SUCCESS) {
  91                          DEBUG(10, ("acl_read: cannot get descriptor\n"));
  92                          ret = LDB_ERR_OPERATIONS_ERROR;
  93                          goto fail;
  94                  }
  95                  sid = samdb_result_dom_sid(tmp_ctx, acl_res->msgs[0], "objectSid");
  96                  /* get the parent guid */
  97                  parent = ldb_msg_find_element(acl_res->msgs[0], "parentGUID");
  98                  if (parent) {
  99                          /* the object has a parent, so we have to check for visibility */
 100                          struct GUID parent_guid = samdb_result_guid(acl_res->msgs[0], "parentGUID");
 101                          ret = dsdb_module_check_access_on_guid(ac->module,
 102                                                                 tmp_ctx,
 103                                                                 &parent_guid,
 104                                                                 SEC_ADS_LIST,
 105                                                                 NULL);
 106                          if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
 107                                  talloc_free(tmp_ctx);
 108                                  return LDB_SUCCESS;
 109                          } else if (ret != LDB_SUCCESS) {
 110                                  goto fail;
 111                          }
 112                  }
 113                  /* for every element in the message check RP */
 114                  i = 0;
 115                  while (i < ares->message->num_elements) {
 116                          char *p, *new_attr;
 117                          const struct dsdb_attribute *attr;
 118                          p = strchr(ares->message->elements[i].name, ';');
 119                          if (!p) {
 120                                  attr =  dsdb_attribute_by_lDAPDisplayName(ac->schema,
 121                                                                            ares->message->elements[i].name);
 122                          } else {
 123                                  new_attr = talloc_strndup(tmp_ctx,
 124                                                            ares->message->elements[i].name,
 125                                                            (size_t)(p -ares->message->elements[i].name));
 126                                  if (!new_attr) {
 127                                          ldb_oom(ldb);
 128                                          ret = LDB_ERR_OPERATIONS_ERROR;
 129                                          goto fail;
 130                                  }
 131                                  attr =  dsdb_attribute_by_lDAPDisplayName(ac->schema,
 132                                                                            new_attr);
 133                                  talloc_free(new_attr);
 134                          }
 135
 136                          if (!attr) {
 137                                  DEBUG(2, ("acl_read: cannot find attribute %s in schema\n",
 138                                            ares->message->elements[i].name));
 139                                  ret = LDB_ERR_OPERATIONS_ERROR;
 140                                  goto fail;
 141                          }
 142                          /* nTSecurityDescriptor is a special case */
 143                          if (ldb_attr_cmp("nTSecurityDescriptor",
 144                                           ares->message->elements[i].name) == 0) {
 145                                  ret = acl_check_access_on_attribute(ac->module,
 146                                                                      tmp_ctx,
 147                                                                      sd,
 148                                                                      sid,
 149                                                                      SEC_FLAG_SYSTEM_SECURITY|SEC_STD_READ_CONTROL,
 150                                                                      attr);
 151                          } else {
 152                                  ret = acl_check_access_on_attribute(ac->module,
 153                                                                      tmp_ctx,
 154                                                                      sd,
 155                                                                      sid,
 156                                                                      SEC_ADS_READ_PROP,
 157                                                                      attr);
 158                          }
 159                          if (ret == LDB_SUCCESS) {
 160                                  i++;
 161                          } else if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
 162                                  /* do not return this entry if attribute is
 163                                             part of the search filter */
 164                                  if (dsdb_attr_in_parse_tree(ac->req->op.search.tree,
 165                                                              ares->message->elements[i].name)) {
 166                                          talloc_free(tmp_ctx);
 167                                          return LDB_SUCCESS;
 168                                  }
 169                                  ldb_msg_remove_attr(ares->message, ares->message->elements[i].name);
 170                          } else {
 171                                  goto fail;
 172                          }
 173                  }
 174                  talloc_free(tmp_ctx);
 175                  return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 176          case LDB_REPLY_REFERRAL:
 177                  return ldb_module_send_referral(ac->req, ares->referral);
 178          case LDB_REPLY_DONE:
 179                  return ldb_module_done(ac->req, ares->controls,
 180                                         ares->response, LDB_SUCCESS);
 181
 182          }
 183          return LDB_SUCCESS;
 184 fail:
 185          talloc_free(tmp_ctx);
 186          return ldb_module_done(ac->req, NULL, NULL, ret);
 187 }
 188
 189
 190 static int aclread_search(struct ldb_module *module, struct ldb_request *req)
 191 {
 192         struct ldb_context *ldb;
 193         int ret;
 194         bool block_anonymous;
 195         struct aclread_context *ac;
 196         struct ldb_request *down_req;
 197         struct ldb_control *as_system = ldb_request_get_control(req, LDB_CONTROL_AS_SYSTEM_OID);
 198         struct auth_session_info *session_info;
 199         struct ldb_result *res;
 200         struct ldb_message_element *parent;
 201         struct aclread_private *p;
 202         bool is_untrusted = ldb_req_is_untrusted(req);
 203         static const char *acl_attrs[] = {
 204                  "parentGUID",
 205                  NULL
 206         };
 207
 208         ldb = ldb_module_get_ctx(module);
 209         p = talloc_get_type(ldb_module_get_private(module), struct aclread_private);
 210
 211         /* skip access checks if we are system or system control is supplied
 212          * or this is not LDAP server request */
 213         if (!p || !p->enabled ||
 214             dsdb_module_am_system(module)
 215             || as_system || !is_untrusted) {
 216                 return ldb_next_request(module, req);
 217         }
 218         /* no checks on special dn */
 219         if (ldb_dn_is_special(req->op.search.base)) {
 220                 return ldb_next_request(module, req);
 221         }
 222         /* allow all access to rootDSE */
 223         if (req->op.search.scope == LDB_SCOPE_BASE && ldb_dn_is_null(req->op.search.base)) {
 224                 return ldb_next_request(module, req);
 225         }
 226
 227         session_info = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
 228         if (session_info && security_token_is_anonymous(session_info->security_token)) {
 229                 block_anonymous = dsdb_block_anonymous_ops(module);
 230                 if (block_anonymous) {
 231                         return ldb_error(ldb, LDB_ERR_OPERATIONS_ERROR,
 232                                          "This request is not allowed to an anonymous connection.");
 233                 }
 234         }
 235
 236         /* check accessibility of base */
 237         if (!ldb_dn_is_null(req->op.search.base)) {
 238                 ret = dsdb_module_search_dn(module, req, &res, req->op.search.base,
 239                                             acl_attrs,
 240                                             DSDB_FLAG_NEXT_MODULE |
 241                                             DSDB_SEARCH_SHOW_DELETED);
 242                 if (ret != LDB_SUCCESS) {
 243                         return ldb_error(ldb, ret,
 244                                          "acl_read: Error retrieving SD for base.");
 245                 }
 246
 247                 parent = ldb_msg_find_element(res->msgs[0], "parentGUID");
 248                 if (parent) {
 249                         /* the object has a parent, so we have to check for visibility */
 250                         struct GUID parent_guid = samdb_result_guid(res->msgs[0], "parentGUID");
 251                         ret = dsdb_module_check_access_on_guid(module,
 252                                                                req,
 253                                                                &parent_guid,
 254                                                                SEC_ADS_LIST,
 255                                                                NULL);
 256                         if (ret == LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS) {
 257                                 return ldb_module_done(req, NULL, NULL, LDB_ERR_NO_SUCH_OBJECT);
 258                         } else if (ret != LDB_SUCCESS) {
 259                                 return ldb_module_done(req, NULL, NULL, ret);
 260                         }
 261                 }
 262         }
 263         ac = talloc_zero(req, struct aclread_context);
 264         if (ac == NULL) {
 265                 return ldb_oom(ldb);
 266         }
 267         ac->module = module;
 268         ac->req = req;
 269         ac->schema = dsdb_get_schema(ldb, req);
 270         if (!ac->schema) {
 271                 return ldb_operr(ldb);
 272         }
 273
 274         ret = ldb_build_search_req_ex(&down_req,
 275                                       ldb, ac,
 276                                       req->op.search.base,
 277                                       req->op.search.scope,
 278                                       req->op.search.tree,
 279                                       req->op.search.attrs,
 280                                       req->controls,
 281                                       ac, aclread_callback,
 282                                       req);
 283
 284         if (ret != LDB_SUCCESS) {
 285                 return LDB_ERR_OPERATIONS_ERROR;
 286         }
 287
 288         return ldb_next_request(module, down_req);
 289 }
 290
 291 static int aclread_init(struct ldb_module *module)
 292 {
 293         struct ldb_context *ldb = ldb_module_get_ctx(module);
 294         struct aclread_private *p = talloc_zero(module, struct aclread_private);
 295         if (p == NULL) {
 296                 return ldb_module_oom(module);
 297         }
 298         p->enabled = lpcfg_parm_bool(ldb_get_opaque(ldb, "loadparm"), NULL, "acl", "search", false);
 299         ldb_module_set_private(module, p);
 300         return ldb_next_init(module);
 301 }
 302
 303 static const struct ldb_module_ops ldb_aclread_module_ops = {
 304         .name              = "aclread",
 305         .search            = aclread_search,
 306         .init_context      = aclread_init
 307 };
 308
 309 int ldb_aclread_module_init(const char *version)
 310 {
 311         LDB_MODULE_CHECK_VERSION(version);
 312         return ldb_register_module(&ldb_aclread_module_ops);
 313 }