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 **objectclass_list, **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         objectclass_list = talloc_array(mem_ctx, const char *, oc_el->num_values + 1);
 122         if (!objectclass_list) {
 123                 ldb_oom(ldb);
 124                 talloc_free(mem_ctx);
 125                 return LDB_ERR_OPERATIONS_ERROR;
 126         }
 127
 128         for (i=0; oc_el && i < oc_el->num_values; i++) {
 129                 objectclass_list[i] = (const char *)oc_el->values[i].data;
 130         }
 131         objectclass_list[i] = NULL;
 132
 133         attr_list = dsdb_full_attribute_list(mem_ctx, schema, objectclass_list, DSDB_SCHEMA_ALL);
 134         if (!attr_list) {
 135                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 136                 talloc_free(mem_ctx);
 137                 return LDB_ERR_OPERATIONS_ERROR;
 138         }
 139
 140         for (i=0; attr_list && attr_list[i]; i++) {
 141                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 142         }
 143         talloc_free(mem_ctx);
 144         return LDB_SUCCESS;
 145
 146 }
 147 /* read all objectClasses */
 148
 149 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 150                                    const char *attrName)
 151 {
 152         struct ldb_message_element *oc_el;
 153         struct ldb_message_element *allowedClasses;
 154         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 155         const struct dsdb_class *sclass;
 156         int i, j, ret;
 157
 158         /* If we don't have a schema yet, we can't do anything... */
 159         if (schema == NULL) {
 160                 return LDB_SUCCESS;
 161         }
 162
 163         /* Must remove any existing attribute, or else confusion reins */
 164         ldb_msg_remove_attr(msg, attrName);
 165         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 166         if (ret != LDB_SUCCESS) {
 167                 return ret;
 168         }
 169
 170         /* To ensure that oc_el is valid, we must look for it after
 171            we alter the element array in ldb_msg_add_empty() */
 172         oc_el = ldb_msg_find_element(msg, "objectClass");
 173
 174         for (i=0; oc_el && i < oc_el->num_values; i++) {
 175                 sclass = dsdb_class_by_lDAPDisplayName(schema, (const char *)oc_el->values[i].data);
 176                 if (!sclass) {
 177                         /* We don't know this class?  what is going on? */
 178                         continue;
 179                 }
 180
 181                 for (j=0; sclass->possibleInferiors && sclass->possibleInferiors[j]; j++) {
 182                         ldb_msg_add_string(msg, attrName, sclass->possibleInferiors[j]);
 183                 }
 184         }
 185
 186         if (allowedClasses->num_values > 1) {
 187                 qsort(allowedClasses->values,
 188                       allowedClasses->num_values,
 189                       sizeof(*allowedClasses->values),
 190                       (comparison_fn_t)data_blob_cmp);
 191
 192                 for (i=1 ; i < allowedClasses->num_values; i++) {
 193
 194                         struct ldb_val *val1 = &allowedClasses->values[i-1];
 195                         struct ldb_val *val2 = &allowedClasses->values[i];
 196                         if (data_blob_cmp(val1, val2) == 0) {
 197                                 memmove(val1, val2, (allowedClasses->num_values - i) * sizeof( struct ldb_val));
 198                                 allowedClasses->num_values--;
 199                                 i--;
 200                         }
 201                 }
 202         }
 203
 204         return LDB_SUCCESS;
 205
 206 }
 207
 208 /* find all attributes allowed by all these objectClasses */
 209
 210 static int kludge_acl_callback(struct ldb_request *req, struct ldb_reply *ares)
 211 {
 212         struct ldb_context *ldb;
 213         struct kludge_acl_context *ac;
 214         struct kludge_private_data *data;
 215         int i, ret;
 216
 217         ac = talloc_get_type(req->context, struct kludge_acl_context);
 218         data = talloc_get_type(ldb_module_get_private(ac->module), struct kludge_private_data);
 219         ldb = ldb_module_get_ctx(ac->module);
 220
 221         if (!ares) {
 222                 return ldb_module_done(ac->req, NULL, NULL,
 223                                         LDB_ERR_OPERATIONS_ERROR);
 224         }
 225         if (ares->error != LDB_SUCCESS) {
 226                 return ldb_module_done(ac->req, ares->controls,
 227                                         ares->response, ares->error);
 228         }
 229
 230         switch (ares->type) {
 231         case LDB_REPLY_ENTRY:
 232                 if (ac->allowedAttributes) {
 233                         ret = kludge_acl_allowedAttributes(ldb,
 234                                                    ares->message,
 235                                                    "allowedAttributes");
 236                         if (ret != LDB_SUCCESS) {
 237                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 238                         }
 239                 }
 240                 if (ac->allowedChildClasses) {
 241                         ret = kludge_acl_childClasses(ldb,
 242                                                 ares->message,
 243                                                 "allowedChildClasses");
 244                         if (ret != LDB_SUCCESS) {
 245                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 246                         }
 247                 }
 248
 249                 if (data && data->password_attrs) /* if we are not initialized just get through */
 250                 {
 251                         switch (ac->user_type) {
 252                         case SECURITY_SYSTEM:
 253                                 if (ac->allowedAttributesEffective) {
 254                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 255                                                                         "allowedAttributesEffective");
 256                                         if (ret != LDB_SUCCESS) {
 257                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 258                                         }
 259                                 }
 260                                 if (ac->allowedChildClassesEffective) {
 261                                         ret = kludge_acl_childClasses(ldb, ares->message,
 262                                                                         "allowedChildClassesEffective");
 263                                         if (ret != LDB_SUCCESS) {
 264                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 265                                         }
 266                                 }
 267                                 break;
 268
 269                         case SECURITY_ADMINISTRATOR:
 270                                 if (ac->allowedAttributesEffective) {
 271                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 272                                                                         "allowedAttributesEffective");
 273                                         if (ret != LDB_SUCCESS) {
 274                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 275                                         }
 276                                 }
 277                                 if (ac->allowedChildClassesEffective) {
 278                                         ret = kludge_acl_childClasses(ldb, ares->message,
 279                                                                         "allowedChildClassesEffective");
 280                                         if (ret != LDB_SUCCESS) {
 281                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 282                                         }
 283                                 }
 284                                 /* fall through */
 285                         default:
 286                                 /* remove password attributes */
 287                                 for (i = 0; data->password_attrs[i]; i++) {
 288                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 289                                 }
 290                         }
 291                 }
 292
 293                 if (ac->allowedAttributes ||
 294                     ac->allowedAttributesEffective ||
 295                     ac->allowedChildClasses ||
 296                     ac->allowedChildClassesEffective) {
 297
 298                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 299                             !ldb_attr_in_list(ac->attrs, "*")) {
 300
 301                                 ldb_msg_remove_attr(ares->message,
 302                                                     "objectClass");
 303                         }
 304                 }
 305
 306                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 307
 308         case LDB_REPLY_REFERRAL:
 309                 return ldb_module_send_referral(ac->req, ares->referral);
 310
 311         case LDB_REPLY_DONE:
 312                 return ldb_module_done(ac->req, ares->controls,
 313                                         ares->response, LDB_SUCCESS);
 314
 315         }
 316         return LDB_SUCCESS;
 317 }
 318
 319 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 320 {
 321         struct ldb_context *ldb;
 322         struct kludge_acl_context *ac;
 323         struct ldb_request *down_req;
 324         struct kludge_private_data *data;
 325         const char * const *attrs;
 326         int ret, i;
 327         struct ldb_control *sd_control;
 328         struct ldb_control **sd_saved_controls;
 329
 330         ldb = ldb_module_get_ctx(module);
 331
 332         ac = talloc(req, struct kludge_acl_context);
 333         if (ac == NULL) {
 334                 ldb_oom(ldb);
 335                 return LDB_ERR_OPERATIONS_ERROR;
 336         }
 337
 338         data = talloc_get_type(ldb_module_get_private(module), struct kludge_private_data);
 339
 340         ac->module = module;
 341         ac->req = req;
 342         ac->user_type = what_is_user(module);
 343         ac->attrs = req->op.search.attrs;
 344
 345         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 346
 347         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 348
 349         ac->allowedChildClasses = ldb_attr_in_list(req->op.search.attrs, "allowedChildClasses");
 350
 351         ac->allowedChildClassesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedChildClassesEffective");
 352
 353         if (ac->allowedAttributes || ac->allowedAttributesEffective || ac->allowedChildClasses || ac->allowedChildClassesEffective) {
 354                 attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "objectClass");
 355         } else {
 356                 attrs = req->op.search.attrs;
 357         }
 358
 359         /* replace any attributes in the parse tree that are private,
 360            so we don't allow a search for 'userPassword=penguin',
 361            just as we would not allow that attribute to be returned */
 362         switch (ac->user_type) {
 363         case SECURITY_SYSTEM:
 364                 break;
 365         default:
 366         /* FIXME: We should copy the tree and keep the original unmodified. */
 367                 /* remove password attributes */
 368
 369                 if (!data || !data->password_attrs) {
 370                         break;
 371                 }
 372                 for (i = 0; data->password_attrs[i]; i++) {
 373                         ldb_parse_tree_attr_replace(req->op.search.tree,
 374                                                     data->password_attrs[i],
 375                                                     "kludgeACLredactedattribute");
 376                 }
 377         }
 378
 379         ret = ldb_build_search_req_ex(&down_req,
 380                                         ldb, ac,
 381                                         req->op.search.base,
 382                                         req->op.search.scope,
 383                                         req->op.search.tree,
 384                                         attrs,
 385                                         req->controls,
 386                                         ac, kludge_acl_callback,
 387                                         req);
 388         if (ret != LDB_SUCCESS) {
 389                 return LDB_ERR_OPERATIONS_ERROR;
 390         }
 391
 392         /* check if there's an SD_FLAGS control */
 393         sd_control = ldb_request_get_control(down_req, LDB_CONTROL_SD_FLAGS_OID);
 394         if (sd_control) {
 395                 /* save it locally and remove it from the list */
 396                 /* we do not need to replace them later as we
 397                  * are keeping the original req intact */
 398                 if (!save_controls(sd_control, down_req, &sd_saved_controls)) {
 399                         return LDB_ERR_OPERATIONS_ERROR;
 400                 }
 401         }
 402
 403         /* perform the search */
 404         return ldb_next_request(module, down_req);
 405 }
 406
 407 /* ANY change type */
 408 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 409 {
 410         struct ldb_context *ldb = ldb_module_get_ctx(module);
 411         enum security_user_level user_type = what_is_user(module);
 412         switch (user_type) {
 413         case SECURITY_SYSTEM:
 414         case SECURITY_ADMINISTRATOR:
 415                 return ldb_next_request(module, req);
 416         default:
 417                 ldb_asprintf_errstring(ldb,
 418                                        "kludge_acl_change: "
 419                                        "attempted database modify not permitted. "
 420                                        "User %s is not SYSTEM or an administrator",
 421                                        user_name(req, module));
 422                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 423         }
 424 }
 425
 426 static int kludge_acl_extended(struct ldb_module *module, struct ldb_request *req)
 427 {
 428         struct ldb_context *ldb = ldb_module_get_ctx(module);
 429         enum security_user_level user_type;
 430
 431         /* allow everybody to read the sequence number */
 432         if (strcmp(req->op.extended.oid,
 433                    LDB_EXTENDED_SEQUENCE_NUMBER) == 0) {
 434                 return ldb_next_request(module, req);
 435         }
 436
 437         user_type = what_is_user(module);
 438
 439         switch (user_type) {
 440         case SECURITY_SYSTEM:
 441         case SECURITY_ADMINISTRATOR:
 442                 return ldb_next_request(module, req);
 443         default:
 444                 ldb_asprintf_errstring(ldb,
 445                                        "kludge_acl_change: "
 446                                        "attempted database modify not permitted. "
 447                                        "User %s is not SYSTEM or an administrator",
 448                                        user_name(req, module));
 449                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 450         }
 451 }
 452
 453 static int kludge_acl_init(struct ldb_module *module)
 454 {
 455         struct ldb_context *ldb;
 456         int ret, i;
 457         TALLOC_CTX *mem_ctx = talloc_new(module);
 458         static const char *attrs[] = { "passwordAttribute", NULL };
 459         struct ldb_result *res;
 460         struct ldb_message *msg;
 461         struct ldb_message_element *password_attributes;
 462
 463         struct kludge_private_data *data;
 464
 465         ldb = ldb_module_get_ctx(module);
 466
 467         data = talloc(module, struct kludge_private_data);
 468         if (data == NULL) {
 469                 ldb_oom(ldb);
 470                 return LDB_ERR_OPERATIONS_ERROR;
 471         }
 472
 473         data->password_attrs = NULL;
 474         ldb_module_set_private(module, data);
 475
 476         if (!mem_ctx) {
 477                 ldb_oom(ldb);
 478                 return LDB_ERR_OPERATIONS_ERROR;
 479         }
 480
 481         ret = ldb_search(ldb, mem_ctx, &res,
 482                          ldb_dn_new(mem_ctx, ldb, "@KLUDGEACL"),
 483                          LDB_SCOPE_BASE, attrs, NULL);
 484         if (ret != LDB_SUCCESS) {
 485                 goto done;
 486         }
 487         if (res->count == 0) {
 488                 goto done;
 489         }
 490
 491         if (res->count > 1) {
 492                 talloc_free(mem_ctx);
 493                 return LDB_ERR_CONSTRAINT_VIOLATION;
 494         }
 495
 496         msg = res->msgs[0];
 497
 498         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 499         if (!password_attributes) {
 500                 goto done;
 501         }
 502         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 503         if (!data->password_attrs) {
 504                 talloc_free(mem_ctx);
 505                 ldb_oom(ldb);
 506                 return LDB_ERR_OPERATIONS_ERROR;
 507         }
 508         for (i=0; i < password_attributes->num_values; i++) {
 509                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 510                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 511         }
 512         data->password_attrs[i] = NULL;
 513
 514         ret = ldb_mod_register_control(module, LDB_CONTROL_SD_FLAGS_OID);
 515         if (ret != LDB_SUCCESS) {
 516                 ldb_debug(ldb, LDB_DEBUG_ERROR,
 517                         "partition: Unable to register control with rootdse!\n");
 518                 return LDB_ERR_OPERATIONS_ERROR;
 519         }
 520
 521 done:
 522         talloc_free(mem_ctx);
 523         return ldb_next_init(module);
 524 }
 525
 526 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 527         .name              = "kludge_acl",
 528         .search            = kludge_acl_search,
 529         .add               = kludge_acl_change,
 530         .modify            = kludge_acl_change,
 531         .del               = kludge_acl_change,
 532         .rename            = kludge_acl_change,
 533         .extended          = kludge_acl_extended,
 534         .init_context      = kludge_acl_init
 535 };