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 #include "param/param.h"
  39
  40 /* Kludge ACL rules:
  41  *
  42  * - System can read passwords
  43  * - Administrators can write anything
  44  * - Users can read anything that is not a password
  45  *
  46  */
  47
  48 struct kludge_private_data {
  49         const char **password_attrs;
  50         bool acl_perform;
  51 };
  52
  53 static enum security_user_level what_is_user(struct ldb_module *module)
  54 {
  55         struct ldb_context *ldb = ldb_module_get_ctx(module);
  56         struct auth_session_info *session_info
  57                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  58         return security_session_user_level(session_info);
  59 }
  60
  61 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  62 {
  63         struct ldb_context *ldb = ldb_module_get_ctx(module);
  64         struct auth_session_info *session_info
  65                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  66         if (!session_info) {
  67                 return "UNKNOWN (NULL)";
  68         }
  69
  70         return talloc_asprintf(mem_ctx, "%s\\%s",
  71                                session_info->server_info->domain_name,
  72                                session_info->server_info->account_name);
  73 }
  74
  75 /* search */
  76 struct kludge_acl_context {
  77
  78         struct ldb_module *module;
  79         struct ldb_request *req;
  80
  81         enum security_user_level user_type;
  82         bool allowedAttributes;
  83         bool allowedAttributesEffective;
  84         bool allowedChildClasses;
  85         bool allowedChildClassesEffective;
  86         const char * const *attrs;
  87 };
  88
  89 /* read all objectClasses */
  90
  91 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
  92                                         const char *attrName)
  93 {
  94         struct ldb_message_element *oc_el;
  95         struct ldb_message_element *allowedAttributes;
  96         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
  97         TALLOC_CTX *mem_ctx;
  98         const char **attr_list;
  99         int i, ret;
 100
 101         /* If we don't have a schema yet, we can't do anything... */
 102         if (schema == NULL) {
 103                 return LDB_SUCCESS;
 104         }
 105
 106         /* Must remove any existing attribute, or else confusion reins */
 107         ldb_msg_remove_attr(msg, attrName);
 108         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 109         if (ret != LDB_SUCCESS) {
 110                 return ret;
 111         }
 112
 113         mem_ctx = talloc_new(msg);
 114         if (!mem_ctx) {
 115                 ldb_oom(ldb);
 116                 return LDB_ERR_OPERATIONS_ERROR;
 117         }
 118
 119         /* To ensure that oc_el is valid, we must look for it after
 120            we alter the element array in ldb_msg_add_empty() */
 121         oc_el = ldb_msg_find_element(msg, "objectClass");
 122
 123         attr_list = dsdb_full_attribute_list(mem_ctx, schema, oc_el, DSDB_SCHEMA_ALL);
 124         if (!attr_list) {
 125                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 126                 talloc_free(mem_ctx);
 127                 return LDB_ERR_OPERATIONS_ERROR;
 128         }
 129
 130         for (i=0; attr_list && attr_list[i]; i++) {
 131                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 132         }
 133         talloc_free(mem_ctx);
 134         return LDB_SUCCESS;
 135
 136 }
 137 /* read all objectClasses */
 138
 139 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 140                                    const char *attrName)
 141 {
 142         struct ldb_message_element *oc_el;
 143         struct ldb_message_element *allowedClasses;
 144         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 145         const struct dsdb_class *sclass;
 146         int i, j, ret;
 147
 148         /* If we don't have a schema yet, we can't do anything... */
 149         if (schema == NULL) {
 150                 return LDB_SUCCESS;
 151         }
 152
 153         /* Must remove any existing attribute, or else confusion reins */
 154         ldb_msg_remove_attr(msg, attrName);
 155         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 156         if (ret != LDB_SUCCESS) {
 157                 return ret;
 158         }
 159
 160         /* To ensure that oc_el is valid, we must look for it after
 161            we alter the element array in ldb_msg_add_empty() */
 162         oc_el = ldb_msg_find_element(msg, "objectClass");
 163
 164         for (i=0; oc_el && i < oc_el->num_values; i++) {
 165                 sclass = dsdb_class_by_lDAPDisplayName_ldb_val(schema, &oc_el->values[i]);
 166                 if (!sclass) {
 167                         /* We don't know this class?  what is going on? */
 168                         continue;
 169                 }
 170
 171                 for (j=0; sclass->possibleInferiors && sclass->possibleInferiors[j]; j++) {
 172                         ldb_msg_add_string(msg, attrName, sclass->possibleInferiors[j]);
 173                 }
 174         }
 175
 176         if (allowedClasses->num_values > 1) {
 177                 qsort(allowedClasses->values,
 178                       allowedClasses->num_values,
 179                       sizeof(*allowedClasses->values),
 180                       (comparison_fn_t)data_blob_cmp);
 181
 182                 for (i=1 ; i < allowedClasses->num_values; i++) {
 183
 184                         struct ldb_val *val1 = &allowedClasses->values[i-1];
 185                         struct ldb_val *val2 = &allowedClasses->values[i];
 186                         if (data_blob_cmp(val1, val2) == 0) {
 187                                 memmove(val1, val2, (allowedClasses->num_values - i) * sizeof( struct ldb_val));
 188                                 allowedClasses->num_values--;
 189                                 i--;
 190                         }
 191                 }
 192         }
 193
 194         return LDB_SUCCESS;
 195
 196 }
 197
 198 /* find all attributes allowed by all these objectClasses */
 199
 200 static int kludge_acl_callback(struct ldb_request *req, struct ldb_reply *ares)
 201 {
 202         struct ldb_context *ldb;
 203         struct kludge_acl_context *ac;
 204         struct kludge_private_data *data;
 205         int i, ret;
 206
 207         ac = talloc_get_type(req->context, struct kludge_acl_context);
 208         data = talloc_get_type(ldb_module_get_private(ac->module), struct kludge_private_data);
 209         ldb = ldb_module_get_ctx(ac->module);
 210
 211         if (!ares) {
 212                 return ldb_module_done(ac->req, NULL, NULL,
 213                                         LDB_ERR_OPERATIONS_ERROR);
 214         }
 215         if (ares->error != LDB_SUCCESS) {
 216                 return ldb_module_done(ac->req, ares->controls,
 217                                         ares->response, ares->error);
 218         }
 219
 220         switch (ares->type) {
 221         case LDB_REPLY_ENTRY:
 222                 if (ac->allowedAttributes) {
 223                         ret = kludge_acl_allowedAttributes(ldb,
 224                                                    ares->message,
 225                                                    "allowedAttributes");
 226                         if (ret != LDB_SUCCESS) {
 227                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 228                         }
 229                 }
 230                 if (ac->allowedChildClasses) {
 231                         ret = kludge_acl_childClasses(ldb,
 232                                                 ares->message,
 233                                                 "allowedChildClasses");
 234                         if (ret != LDB_SUCCESS) {
 235                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 236                         }
 237                 }
 238
 239                 if (data && data->password_attrs) /* if we are not initialized just get through */
 240                 {
 241                         switch (ac->user_type) {
 242                         case SECURITY_SYSTEM:
 243                                 if (ac->allowedAttributesEffective) {
 244                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 245                                                                         "allowedAttributesEffective");
 246                                         if (ret != LDB_SUCCESS) {
 247                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 248                                         }
 249                                 }
 250                                 if (ac->allowedChildClassesEffective) {
 251                                         ret = kludge_acl_childClasses(ldb, ares->message,
 252                                                                         "allowedChildClassesEffective");
 253                                         if (ret != LDB_SUCCESS) {
 254                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 255                                         }
 256                                 }
 257                                 break;
 258
 259                         case SECURITY_ADMINISTRATOR:
 260                                 if (ac->allowedAttributesEffective) {
 261                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 262                                                                         "allowedAttributesEffective");
 263                                         if (ret != LDB_SUCCESS) {
 264                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 265                                         }
 266                                 }
 267                                 if (ac->allowedChildClassesEffective) {
 268                                         ret = kludge_acl_childClasses(ldb, ares->message,
 269                                                                         "allowedChildClassesEffective");
 270                                         if (ret != LDB_SUCCESS) {
 271                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 272                                         }
 273                                 }
 274                                 /* fall through */
 275                         default:
 276                                 /* remove password attributes */
 277                                 for (i = 0; data->password_attrs[i]; i++) {
 278                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 279                                 }
 280                         }
 281                 }
 282
 283                 if (ac->allowedAttributes ||
 284                     ac->allowedAttributesEffective ||
 285                     ac->allowedChildClasses ||
 286                     ac->allowedChildClassesEffective) {
 287
 288                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 289                             !ldb_attr_in_list(ac->attrs, "*")) {
 290
 291                                 ldb_msg_remove_attr(ares->message,
 292                                                     "objectClass");
 293                         }
 294                 }
 295
 296                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 297
 298         case LDB_REPLY_REFERRAL:
 299                 return ldb_module_send_referral(ac->req, ares->referral);
 300
 301         case LDB_REPLY_DONE:
 302                 return ldb_module_done(ac->req, ares->controls,
 303                                         ares->response, LDB_SUCCESS);
 304
 305         }
 306         return LDB_SUCCESS;
 307 }
 308
 309 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 310 {
 311         struct ldb_context *ldb;
 312         struct kludge_acl_context *ac;
 313         struct ldb_request *down_req;
 314         struct kludge_private_data *data;
 315         const char * const *attrs;
 316         int ret, i;
 317         struct ldb_control *sd_control;
 318         struct ldb_control **sd_saved_controls;
 319
 320         ldb = ldb_module_get_ctx(module);
 321
 322         ac = talloc(req, struct kludge_acl_context);
 323         if (ac == NULL) {
 324                 ldb_oom(ldb);
 325                 return LDB_ERR_OPERATIONS_ERROR;
 326         }
 327
 328         data = talloc_get_type(ldb_module_get_private(module), struct kludge_private_data);
 329
 330         if (data && data->acl_perform)
 331                 return ldb_next_request(module, req);
 332
 333         ac->module = module;
 334         ac->req = req;
 335         ac->user_type = what_is_user(module);
 336         ac->attrs = req->op.search.attrs;
 337
 338         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 339
 340         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 341
 342         ac->allowedChildClasses = ldb_attr_in_list(req->op.search.attrs, "allowedChildClasses");
 343
 344         ac->allowedChildClassesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedChildClassesEffective");
 345
 346         if (ac->allowedAttributes || ac->allowedAttributesEffective || ac->allowedChildClasses || ac->allowedChildClassesEffective) {
 347                 attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "objectClass");
 348         } else {
 349                 attrs = req->op.search.attrs;
 350         }
 351
 352         /* replace any attributes in the parse tree that are private,
 353            so we don't allow a search for 'userPassword=penguin',
 354            just as we would not allow that attribute to be returned */
 355         switch (ac->user_type) {
 356         case SECURITY_SYSTEM:
 357                 break;
 358         default:
 359         /* FIXME: We should copy the tree and keep the original unmodified. */
 360                 /* remove password attributes */
 361
 362                 if (!data || !data->password_attrs) {
 363                         break;
 364                 }
 365                 for (i = 0; data->password_attrs[i]; i++) {
 366                         ldb_parse_tree_attr_replace(req->op.search.tree,
 367                                                     data->password_attrs[i],
 368                                                     "kludgeACLredactedattribute");
 369                 }
 370         }
 371
 372         ret = ldb_build_search_req_ex(&down_req,
 373                                         ldb, ac,
 374                                         req->op.search.base,
 375                                         req->op.search.scope,
 376                                         req->op.search.tree,
 377                                         attrs,
 378                                         req->controls,
 379                                         ac, kludge_acl_callback,
 380                                         req);
 381         if (ret != LDB_SUCCESS) {
 382                 return ret;
 383         }
 384
 385         /* check if there's an SD_FLAGS control */
 386         sd_control = ldb_request_get_control(down_req, LDB_CONTROL_SD_FLAGS_OID);
 387         if (sd_control) {
 388                 /* save it locally and remove it from the list */
 389                 /* we do not need to replace them later as we
 390                  * are keeping the original req intact */
 391                 if (!save_controls(sd_control, down_req, &sd_saved_controls)) {
 392                         return LDB_ERR_OPERATIONS_ERROR;
 393                 }
 394         }
 395
 396         /* perform the search */
 397         return ldb_next_request(module, down_req);
 398 }
 399
 400 /* ANY change type */
 401 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 402 {
 403         struct ldb_context *ldb = ldb_module_get_ctx(module);
 404         enum security_user_level user_type = what_is_user(module);
 405         struct kludge_private_data *data = talloc_get_type(ldb_module_get_private(module),
 406                                                            struct kludge_private_data);
 407
 408         if (data->acl_perform)
 409                 return ldb_next_request(module, req);
 410
 411         switch (user_type) {
 412         case SECURITY_SYSTEM:
 413         case SECURITY_ADMINISTRATOR:
 414                 return ldb_next_request(module, req);
 415         default:
 416                 ldb_asprintf_errstring(ldb,
 417                                        "kludge_acl_change: "
 418                                        "attempted database modify not permitted. "
 419                                        "User %s is not SYSTEM or an administrator",
 420                                        user_name(req, module));
 421                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 422         }
 423 }
 424
 425 static int kludge_acl_extended(struct ldb_module *module, struct ldb_request *req)
 426 {
 427         struct ldb_context *ldb = ldb_module_get_ctx(module);
 428         enum security_user_level user_type;
 429
 430         /* allow everybody to read the sequence number */
 431         if (strcmp(req->op.extended.oid,
 432                    LDB_EXTENDED_SEQUENCE_NUMBER) == 0) {
 433                 return ldb_next_request(module, req);
 434         }
 435
 436         user_type = what_is_user(module);
 437
 438         switch (user_type) {
 439         case SECURITY_SYSTEM:
 440         case SECURITY_ADMINISTRATOR:
 441                 return ldb_next_request(module, req);
 442         default:
 443                 ldb_asprintf_errstring(ldb,
 444                                        "kludge_acl_change: "
 445                                        "attempted database modify not permitted. "
 446                                        "User %s is not SYSTEM or an administrator",
 447                                        user_name(req, module));
 448                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 449         }
 450 }
 451
 452 static int kludge_acl_init(struct ldb_module *module)
 453 {
 454         struct ldb_context *ldb;
 455         int ret, i;
 456         TALLOC_CTX *mem_ctx = talloc_new(module);
 457         static const char *attrs[] = { "passwordAttribute", NULL };
 458         struct ldb_result *res;
 459         struct ldb_message *msg;
 460         struct ldb_message_element *password_attributes;
 461
 462         struct kludge_private_data *data;
 463
 464         ldb = ldb_module_get_ctx(module);
 465
 466         data = talloc(module, struct kludge_private_data);
 467         if (data == NULL) {
 468                 ldb_oom(ldb);
 469                 return LDB_ERR_OPERATIONS_ERROR;
 470         }
 471
 472         data->password_attrs = NULL;
 473         data->acl_perform = lp_parm_bool(ldb_get_opaque(ldb, "loadparm"),
 474                                          NULL, "acl", "perform", false);
 475         ldb_module_set_private(module, data);
 476
 477         if (!mem_ctx) {
 478                 ldb_oom(ldb);
 479                 return LDB_ERR_OPERATIONS_ERROR;
 480         }
 481
 482         ret = ldb_search(ldb, mem_ctx, &res,
 483                          ldb_dn_new(mem_ctx, ldb, "@KLUDGEACL"),
 484                          LDB_SCOPE_BASE, attrs, NULL);
 485         if (ret != LDB_SUCCESS) {
 486                 goto done;
 487         }
 488         if (res->count == 0) {
 489                 goto done;
 490         }
 491
 492         if (res->count > 1) {
 493                 talloc_free(mem_ctx);
 494                 return LDB_ERR_CONSTRAINT_VIOLATION;
 495         }
 496
 497         msg = res->msgs[0];
 498
 499         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 500         if (!password_attributes) {
 501                 goto done;
 502         }
 503         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 504         if (!data->password_attrs) {
 505                 talloc_free(mem_ctx);
 506                 ldb_oom(ldb);
 507                 return LDB_ERR_OPERATIONS_ERROR;
 508         }
 509         for (i=0; i < password_attributes->num_values; i++) {
 510                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 511                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 512         }
 513         data->password_attrs[i] = NULL;
 514
 515         ret = ldb_mod_register_control(module, LDB_CONTROL_SD_FLAGS_OID);
 516         if (ret != LDB_SUCCESS) {
 517                 ldb_debug(ldb, LDB_DEBUG_ERROR,
 518                         "kludge_acl: Unable to register control with rootdse!\n");
 519                 return LDB_ERR_OPERATIONS_ERROR;
 520         }
 521
 522 done:
 523         talloc_free(mem_ctx);
 524         return ldb_next_init(module);
 525 }
 526
 527 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 528         .name              = "kludge_acl",
 529         .search            = kludge_acl_search,
 530         .add               = kludge_acl_change,
 531         .modify            = kludge_acl_change,
 532         .del               = kludge_acl_change,
 533         .rename            = kludge_acl_change,
 534         .extended          = kludge_acl_extended,
 535         .init_context      = kludge_acl_init
 536 };