source4/dsdb/samdb/ldb_modules/kludge_acl.c

   1 /*
   2    ldb database library
   3
   4    Copyright (C) Andrew Bartlett 2005
   5    Copyright (C) Simo Sorce 2006-2008
   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 kludge ACL module
  25  *
  26  *  Description: Simple module to enforce a simple form of access
  27  *               control, sufficient for securing a default Samba4
  28  *               installation.
  29  *
  30  *  Author: Andrew Bartlett
  31  */
  32
  33 #include "includes.h"
  34 #include "ldb_module.h"
  35 #include "auth/auth.h"
  36 #include "libcli/security/security.h"
  37 #include "dsdb/samdb/samdb.h"
  38
  39 /* Kludge ACL rules:
  40  *
  41  * - System can read passwords
  42  * - Administrators can write anything
  43  * - Users can read anything that is not a password
  44  *
  45  */
  46
  47 struct kludge_private_data {
  48         const char **password_attrs;
  49 };
  50
  51 static enum security_user_level what_is_user(struct ldb_module *module)
  52 {
  53         struct ldb_context *ldb = ldb_module_get_ctx(module);
  54         struct auth_session_info *session_info
  55                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  56         return security_session_user_level(session_info);
  57 }
  58
  59 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  60 {
  61         struct ldb_context *ldb = ldb_module_get_ctx(module);
  62         struct auth_session_info *session_info
  63                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  64         if (!session_info) {
  65                 return "UNKNOWN (NULL)";
  66         }
  67
  68         return talloc_asprintf(mem_ctx, "%s\\%s",
  69                                session_info->server_info->domain_name,
  70                                session_info->server_info->account_name);
  71 }
  72
  73 /* search */
  74 struct kludge_acl_context {
  75
  76         struct ldb_module *module;
  77         struct ldb_request *req;
  78
  79         enum security_user_level user_type;
  80         bool allowedAttributes;
  81         bool allowedAttributesEffective;
  82         bool allowedChildClasses;
  83         bool allowedChildClassesEffective;
  84         const char * const *attrs;
  85 };
  86
  87 /* read all objectClasses */
  88
  89 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
  90                                         const char *attrName)
  91 {
  92         struct ldb_message_element *oc_el;
  93         struct ldb_message_element *allowedAttributes;
  94         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
  95         TALLOC_CTX *mem_ctx;
  96         const char **attr_list;
  97         int i, ret;
  98
  99         /* If we don't have a schema yet, we can't do anything... */
 100         if (schema == NULL) {
 101                 return LDB_SUCCESS;
 102         }
 103
 104         /* Must remove any existing attribute, or else confusion reins */
 105         ldb_msg_remove_attr(msg, attrName);
 106         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 107         if (ret != LDB_SUCCESS) {
 108                 return ret;
 109         }
 110
 111         mem_ctx = talloc_new(msg);
 112         if (!mem_ctx) {
 113                 ldb_oom(ldb);
 114                 return LDB_ERR_OPERATIONS_ERROR;
 115         }
 116
 117         /* To ensure that oc_el is valid, we must look for it after
 118            we alter the element array in ldb_msg_add_empty() */
 119         oc_el = ldb_msg_find_element(msg, "objectClass");
 120
 121         attr_list = dsdb_full_attribute_list(mem_ctx, schema, oc_el, DSDB_SCHEMA_ALL);
 122         if (!attr_list) {
 123                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 124                 talloc_free(mem_ctx);
 125                 return LDB_ERR_OPERATIONS_ERROR;
 126         }
 127
 128         for (i=0; attr_list && attr_list[i]; i++) {
 129                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 130         }
 131         talloc_free(mem_ctx);
 132         return LDB_SUCCESS;
 133
 134 }
 135 /* read all objectClasses */
 136
 137 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 138                                    const char *attrName)
 139 {
 140         struct ldb_message_element *oc_el;
 141         struct ldb_message_element *allowedClasses;
 142         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 143         const struct dsdb_class *sclass;
 144         int i, j, ret;
 145
 146         /* If we don't have a schema yet, we can't do anything... */
 147         if (schema == NULL) {
 148                 return LDB_SUCCESS;
 149         }
 150
 151         /* Must remove any existing attribute, or else confusion reins */
 152         ldb_msg_remove_attr(msg, attrName);
 153         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 154         if (ret != LDB_SUCCESS) {
 155                 return ret;
 156         }
 157
 158         /* To ensure that oc_el is valid, we must look for it after
 159            we alter the element array in ldb_msg_add_empty() */
 160         oc_el = ldb_msg_find_element(msg, "objectClass");
 161
 162         for (i=0; oc_el && i < oc_el->num_values; i++) {
 163                 sclass = dsdb_class_by_lDAPDisplayName_ldb_val(schema, &oc_el->values[i]);
 164                 if (!sclass) {
 165                         /* We don't know this class?  what is going on? */
 166                         continue;
 167                 }
 168
 169                 for (j=0; sclass->possibleInferiors && sclass->possibleInferiors[j]; j++) {
 170                         ldb_msg_add_string(msg, attrName, sclass->possibleInferiors[j]);
 171                 }
 172         }
 173
 174         if (allowedClasses->num_values > 1) {
 175                 qsort(allowedClasses->values,
 176                       allowedClasses->num_values,
 177                       sizeof(*allowedClasses->values),
 178                       (comparison_fn_t)data_blob_cmp);
 179
 180                 for (i=1 ; i < allowedClasses->num_values; i++) {
 181
 182                         struct ldb_val *val1 = &allowedClasses->values[i-1];
 183                         struct ldb_val *val2 = &allowedClasses->values[i];
 184                         if (data_blob_cmp(val1, val2) == 0) {
 185                                 memmove(val1, val2, (allowedClasses->num_values - i) * sizeof( struct ldb_val));
 186                                 allowedClasses->num_values--;
 187                                 i--;
 188                         }
 189                 }
 190         }
 191
 192         return LDB_SUCCESS;
 193
 194 }
 195
 196 /* find all attributes allowed by all these objectClasses */
 197
 198 static int kludge_acl_callback(struct ldb_request *req, struct ldb_reply *ares)
 199 {
 200         struct ldb_context *ldb;
 201         struct kludge_acl_context *ac;
 202         struct kludge_private_data *data;
 203         int i, ret;
 204
 205         ac = talloc_get_type(req->context, struct kludge_acl_context);
 206         data = talloc_get_type(ldb_module_get_private(ac->module), struct kludge_private_data);
 207         ldb = ldb_module_get_ctx(ac->module);
 208
 209         if (!ares) {
 210                 return ldb_module_done(ac->req, NULL, NULL,
 211                                         LDB_ERR_OPERATIONS_ERROR);
 212         }
 213         if (ares->error != LDB_SUCCESS) {
 214                 return ldb_module_done(ac->req, ares->controls,
 215                                         ares->response, ares->error);
 216         }
 217
 218         switch (ares->type) {
 219         case LDB_REPLY_ENTRY:
 220                 if (ac->allowedAttributes) {
 221                         ret = kludge_acl_allowedAttributes(ldb,
 222                                                    ares->message,
 223                                                    "allowedAttributes");
 224                         if (ret != LDB_SUCCESS) {
 225                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 226                         }
 227                 }
 228                 if (ac->allowedChildClasses) {
 229                         ret = kludge_acl_childClasses(ldb,
 230                                                 ares->message,
 231                                                 "allowedChildClasses");
 232                         if (ret != LDB_SUCCESS) {
 233                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 234                         }
 235                 }
 236
 237                 if (data && data->password_attrs) /* if we are not initialized just get through */
 238                 {
 239                         switch (ac->user_type) {
 240                         case SECURITY_SYSTEM:
 241                                 if (ac->allowedAttributesEffective) {
 242                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 243                                                                         "allowedAttributesEffective");
 244                                         if (ret != LDB_SUCCESS) {
 245                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 246                                         }
 247                                 }
 248                                 if (ac->allowedChildClassesEffective) {
 249                                         ret = kludge_acl_childClasses(ldb, ares->message,
 250                                                                         "allowedChildClassesEffective");
 251                                         if (ret != LDB_SUCCESS) {
 252                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 253                                         }
 254                                 }
 255                                 break;
 256
 257                         case SECURITY_ADMINISTRATOR:
 258                                 if (ac->allowedAttributesEffective) {
 259                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 260                                                                         "allowedAttributesEffective");
 261                                         if (ret != LDB_SUCCESS) {
 262                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 263                                         }
 264                                 }
 265                                 if (ac->allowedChildClassesEffective) {
 266                                         ret = kludge_acl_childClasses(ldb, ares->message,
 267                                                                         "allowedChildClassesEffective");
 268                                         if (ret != LDB_SUCCESS) {
 269                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 270                                         }
 271                                 }
 272                                 /* fall through */
 273                         default:
 274                                 /* remove password attributes */
 275                                 for (i = 0; data->password_attrs[i]; i++) {
 276                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 277                                 }
 278                         }
 279                 }
 280
 281                 if (ac->allowedAttributes ||
 282                     ac->allowedAttributesEffective ||
 283                     ac->allowedChildClasses ||
 284                     ac->allowedChildClassesEffective) {
 285
 286                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 287                             !ldb_attr_in_list(ac->attrs, "*")) {
 288
 289                                 ldb_msg_remove_attr(ares->message,
 290                                                     "objectClass");
 291                         }
 292                 }
 293
 294                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 295
 296         case LDB_REPLY_REFERRAL:
 297                 return ldb_module_send_referral(ac->req, ares->referral);
 298
 299         case LDB_REPLY_DONE:
 300                 return ldb_module_done(ac->req, ares->controls,
 301                                         ares->response, LDB_SUCCESS);
 302
 303         }
 304         return LDB_SUCCESS;
 305 }
 306
 307 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 308 {
 309         struct ldb_context *ldb;
 310         struct kludge_acl_context *ac;
 311         struct ldb_request *down_req;
 312         struct kludge_private_data *data;
 313         const char * const *attrs;
 314         int ret, i;
 315         struct ldb_control *sd_control;
 316         struct ldb_control **sd_saved_controls;
 317
 318         ldb = ldb_module_get_ctx(module);
 319
 320         ac = talloc(req, struct kludge_acl_context);
 321         if (ac == NULL) {
 322                 ldb_oom(ldb);
 323                 return LDB_ERR_OPERATIONS_ERROR;
 324         }
 325
 326         data = talloc_get_type(ldb_module_get_private(module), struct kludge_private_data);
 327
 328         ac->module = module;
 329         ac->req = req;
 330         ac->user_type = what_is_user(module);
 331         ac->attrs = req->op.search.attrs;
 332
 333         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 334
 335         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 336
 337         ac->allowedChildClasses = ldb_attr_in_list(req->op.search.attrs, "allowedChildClasses");
 338
 339         ac->allowedChildClassesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedChildClassesEffective");
 340
 341         if (ac->allowedAttributes || ac->allowedAttributesEffective || ac->allowedChildClasses || ac->allowedChildClassesEffective) {
 342                 attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "objectClass");
 343         } else {
 344                 attrs = req->op.search.attrs;
 345         }
 346
 347         /* replace any attributes in the parse tree that are private,
 348            so we don't allow a search for 'userPassword=penguin',
 349            just as we would not allow that attribute to be returned */
 350         switch (ac->user_type) {
 351         case SECURITY_SYSTEM:
 352                 break;
 353         default:
 354         /* FIXME: We should copy the tree and keep the original unmodified. */
 355                 /* remove password attributes */
 356
 357                 if (!data || !data->password_attrs) {
 358                         break;
 359                 }
 360                 for (i = 0; data->password_attrs[i]; i++) {
 361                         ldb_parse_tree_attr_replace(req->op.search.tree,
 362                                                     data->password_attrs[i],
 363                                                     "kludgeACLredactedattribute");
 364                 }
 365         }
 366
 367         ret = ldb_build_search_req_ex(&down_req,
 368                                         ldb, ac,
 369                                         req->op.search.base,
 370                                         req->op.search.scope,
 371                                         req->op.search.tree,
 372                                         attrs,
 373                                         req->controls,
 374                                         ac, kludge_acl_callback,
 375                                         req);
 376         if (ret != LDB_SUCCESS) {
 377                 return LDB_ERR_OPERATIONS_ERROR;
 378         }
 379
 380         /* check if there's an SD_FLAGS control */
 381         sd_control = ldb_request_get_control(down_req, LDB_CONTROL_SD_FLAGS_OID);
 382         if (sd_control) {
 383                 /* save it locally and remove it from the list */
 384                 /* we do not need to replace them later as we
 385                  * are keeping the original req intact */
 386                 if (!save_controls(sd_control, down_req, &sd_saved_controls)) {
 387                         return LDB_ERR_OPERATIONS_ERROR;
 388                 }
 389         }
 390
 391         /* perform the search */
 392         return ldb_next_request(module, down_req);
 393 }
 394
 395 /* ANY change type */
 396 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 397 {
 398         struct ldb_context *ldb = ldb_module_get_ctx(module);
 399         enum security_user_level user_type = what_is_user(module);
 400         switch (user_type) {
 401         case SECURITY_SYSTEM:
 402         case SECURITY_ADMINISTRATOR:
 403                 return ldb_next_request(module, req);
 404         default:
 405                 ldb_asprintf_errstring(ldb,
 406                                        "kludge_acl_change: "
 407                                        "attempted database modify not permitted. "
 408                                        "User %s is not SYSTEM or an administrator",
 409                                        user_name(req, module));
 410                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 411         }
 412 }
 413
 414 static int kludge_acl_extended(struct ldb_module *module, struct ldb_request *req)
 415 {
 416         struct ldb_context *ldb = ldb_module_get_ctx(module);
 417         enum security_user_level user_type;
 418
 419         /* allow everybody to read the sequence number */
 420         if (strcmp(req->op.extended.oid,
 421                    LDB_EXTENDED_SEQUENCE_NUMBER) == 0) {
 422                 return ldb_next_request(module, req);
 423         }
 424
 425         user_type = what_is_user(module);
 426
 427         switch (user_type) {
 428         case SECURITY_SYSTEM:
 429         case SECURITY_ADMINISTRATOR:
 430                 return ldb_next_request(module, req);
 431         default:
 432                 ldb_asprintf_errstring(ldb,
 433                                        "kludge_acl_change: "
 434                                        "attempted database modify not permitted. "
 435                                        "User %s is not SYSTEM or an administrator",
 436                                        user_name(req, module));
 437                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 438         }
 439 }
 440
 441 static int kludge_acl_init(struct ldb_module *module)
 442 {
 443         struct ldb_context *ldb;
 444         int ret, i;
 445         TALLOC_CTX *mem_ctx = talloc_new(module);
 446         static const char *attrs[] = { "passwordAttribute", NULL };
 447         struct ldb_result *res;
 448         struct ldb_message *msg;
 449         struct ldb_message_element *password_attributes;
 450
 451         struct kludge_private_data *data;
 452
 453         ldb = ldb_module_get_ctx(module);
 454
 455         data = talloc(module, struct kludge_private_data);
 456         if (data == NULL) {
 457                 ldb_oom(ldb);
 458                 return LDB_ERR_OPERATIONS_ERROR;
 459         }
 460
 461         data->password_attrs = NULL;
 462         ldb_module_set_private(module, data);
 463
 464         if (!mem_ctx) {
 465                 ldb_oom(ldb);
 466                 return LDB_ERR_OPERATIONS_ERROR;
 467         }
 468
 469         ret = ldb_search(ldb, mem_ctx, &res,
 470                          ldb_dn_new(mem_ctx, ldb, "@KLUDGEACL"),
 471                          LDB_SCOPE_BASE, attrs, NULL);
 472         if (ret != LDB_SUCCESS) {
 473                 goto done;
 474         }
 475         if (res->count == 0) {
 476                 goto done;
 477         }
 478
 479         if (res->count > 1) {
 480                 talloc_free(mem_ctx);
 481                 return LDB_ERR_CONSTRAINT_VIOLATION;
 482         }
 483
 484         msg = res->msgs[0];
 485
 486         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 487         if (!password_attributes) {
 488                 goto done;
 489         }
 490         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 491         if (!data->password_attrs) {
 492                 talloc_free(mem_ctx);
 493                 ldb_oom(ldb);
 494                 return LDB_ERR_OPERATIONS_ERROR;
 495         }
 496         for (i=0; i < password_attributes->num_values; i++) {
 497                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 498                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 499         }
 500         data->password_attrs[i] = NULL;
 501
 502         ret = ldb_mod_register_control(module, LDB_CONTROL_SD_FLAGS_OID);
 503         if (ret != LDB_SUCCESS) {
 504                 ldb_debug(ldb, LDB_DEBUG_ERROR,
 505                         "kludge_acl: Unable to register control with rootdse!\n");
 506                 return LDB_ERR_OPERATIONS_ERROR;
 507         }
 508
 509 done:
 510         talloc_free(mem_ctx);
 511         return ldb_next_init(module);
 512 }
 513
 514 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 515         .name              = "kludge_acl",
 516         .search            = kludge_acl_search,
 517         .add               = kludge_acl_change,
 518         .modify            = kludge_acl_change,
 519         .del               = kludge_acl_change,
 520         .rename            = kludge_acl_change,
 521         .extended          = kludge_acl_extended,
 522         .init_context      = kludge_acl_init
 523 };