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/include/ldb.h"
  35 #include "ldb/include/ldb_errors.h"
  36 #include "ldb/include/ldb_private.h"
  37 #include "auth/auth.h"
  38 #include "libcli/security/security.h"
  39 #include "dsdb/samdb/samdb.h"
  40
  41 /* Kludge ACL rules:
  42  *
  43  * - System can read passwords
  44  * - Administrators can write anything
  45  * - Users can read anything that is not a password
  46  *
  47  */
  48
  49 struct kludge_private_data {
  50         const char **password_attrs;
  51 };
  52
  53 static enum security_user_level what_is_user(struct ldb_module *module)
  54 {
  55         struct auth_session_info *session_info
  56                 = (struct auth_session_info *)ldb_get_opaque(module->ldb, "sessionInfo");
  57         return security_session_user_level(session_info);
  58 }
  59
  60 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  61 {
  62         struct auth_session_info *session_info
  63                 = (struct auth_session_info *)ldb_get_opaque(module->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         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, 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] = (char *)oc_el->values[i].data;
 130         }
 131         objectclass_list[i] = NULL;
 132
 133         attr_list = dsdb_full_attribute_list(mem_ctx, schema, (const char **)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 *class;
 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                 class = dsdb_class_by_lDAPDisplayName(schema, (const char *)oc_el->values[i].data);
 176                 if (!class) {
 177                         /* We don't know this class?  what is going on? */
 178                         continue;
 179                 }
 180
 181                 for (j=0; class->possibleInferiors && class->possibleInferiors[j]; j++) {
 182                         ldb_msg_add_string(msg, attrName, class->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 kludge_acl_context *ac;
 213         struct kludge_private_data *data;
 214         int i, ret;
 215
 216         ac = talloc_get_type(req->context, struct kludge_acl_context);
 217         data = talloc_get_type(ac->module->private_data, struct kludge_private_data);
 218
 219         if (!ares) {
 220                 return ldb_module_done(ac->req, NULL, NULL,
 221                                         LDB_ERR_OPERATIONS_ERROR);
 222         }
 223         if (ares->error != LDB_SUCCESS) {
 224                 return ldb_module_done(ac->req, ares->controls,
 225                                         ares->response, ares->error);
 226         }
 227
 228         switch (ares->type) {
 229         case LDB_REPLY_ENTRY:
 230                 if (ac->allowedAttributes) {
 231                         ret = kludge_acl_allowedAttributes(ac->module->ldb,
 232                                                    ares->message,
 233                                                    "allowedAttributes");
 234                         if (ret != LDB_SUCCESS) {
 235                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 236                         }
 237                 }
 238                 if (ac->allowedChildClasses) {
 239                         ret = kludge_acl_childClasses(ac->module->ldb,
 240                                                 ares->message,
 241                                                 "allowedChildClasses");
 242                         if (ret != LDB_SUCCESS) {
 243                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 244                         }
 245                 }
 246
 247                 if (data && data->password_attrs) /* if we are not initialized just get through */
 248                 {
 249                         switch (ac->user_type) {
 250                         case SECURITY_SYSTEM:
 251                                 if (ac->allowedAttributesEffective) {
 252                                         ret = kludge_acl_allowedAttributes(ac->module->ldb, ares->message,
 253                                                                         "allowedAttributesEffective");
 254                                         if (ret != LDB_SUCCESS) {
 255                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 256                                         }
 257                                 }
 258                                 if (ac->allowedChildClassesEffective) {
 259                                         ret = kludge_acl_childClasses(ac->module->ldb, ares->message,
 260                                                                         "allowedChildClassesEffective");
 261                                         if (ret != LDB_SUCCESS) {
 262                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 263                                         }
 264                                 }
 265                                 break;
 266
 267                         case SECURITY_ADMINISTRATOR:
 268                                 if (ac->allowedAttributesEffective) {
 269                                         ret = kludge_acl_allowedAttributes(ac->module->ldb, ares->message,
 270                                                                         "allowedAttributesEffective");
 271                                         if (ret != LDB_SUCCESS) {
 272                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 273                                         }
 274                                 }
 275                                 if (ac->allowedChildClassesEffective) {
 276                                         ret = kludge_acl_childClasses(ac->module->ldb, ares->message,
 277                                                                         "allowedChildClassesEffective");
 278                                         if (ret != LDB_SUCCESS) {
 279                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 280                                         }
 281                                 }
 282                                 /* fall through */
 283                         default:
 284                                 /* remove password attributes */
 285                                 for (i = 0; data->password_attrs[i]; i++) {
 286                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 287                                 }
 288                         }
 289                 }
 290
 291                 if (ac->allowedAttributes ||
 292                     ac->allowedAttributesEffective ||
 293                     ac->allowedChildClasses ||
 294                     ac->allowedChildClassesEffective) {
 295
 296                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 297                             !ldb_attr_in_list(ac->attrs, "*")) {
 298
 299                                 ldb_msg_remove_attr(ares->message,
 300                                                     "objectClass");
 301                         }
 302                 }
 303
 304                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 305
 306         case LDB_REPLY_REFERRAL:
 307                 return ldb_module_send_referral(ac->req, ares->referral);
 308
 309         case LDB_REPLY_DONE:
 310                 return ldb_module_done(ac->req, ares->controls,
 311                                         ares->response, LDB_SUCCESS);
 312
 313         }
 314         return LDB_SUCCESS;
 315 }
 316
 317 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 318 {
 319         struct kludge_acl_context *ac;
 320         struct ldb_request *down_req;
 321         struct kludge_private_data *data;
 322         const char * const *attrs;
 323         int ret, i;
 324         struct ldb_control *sd_control;
 325         struct ldb_control **sd_saved_controls;
 326
 327         ac = talloc(req, struct kludge_acl_context);
 328         if (ac == NULL) {
 329                 ldb_oom(module->ldb);
 330                 return LDB_ERR_OPERATIONS_ERROR;
 331         }
 332
 333         data = talloc_get_type(module->private_data, struct kludge_private_data);
 334
 335         ac->module = module;
 336         ac->req = req;
 337         ac->user_type = what_is_user(module);
 338         ac->attrs = req->op.search.attrs;
 339
 340         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 341
 342         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 343
 344         ac->allowedChildClasses = ldb_attr_in_list(req->op.search.attrs, "allowedChildClasses");
 345
 346         ac->allowedChildClassesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedChildClassesEffective");
 347
 348         if (ac->allowedAttributes || ac->allowedAttributesEffective || ac->allowedChildClasses || ac->allowedChildClassesEffective) {
 349                 attrs = ldb_attr_list_copy_add(ac, req->op.search.attrs, "objectClass");
 350         } else {
 351                 attrs = req->op.search.attrs;
 352         }
 353
 354         /* replace any attributes in the parse tree that are private,
 355            so we don't allow a search for 'userPassword=penguin',
 356            just as we would not allow that attribute to be returned */
 357         switch (ac->user_type) {
 358         case SECURITY_SYSTEM:
 359                 break;
 360         default:
 361         /* FIXME: We should copy the tree and keep the original unmodified. */
 362                 /* remove password attributes */
 363
 364                 if (!data || !data->password_attrs) {
 365                         break;
 366                 }
 367                 for (i = 0; data->password_attrs[i]; i++) {
 368                         ldb_parse_tree_attr_replace(req->op.search.tree,
 369                                                     data->password_attrs[i],
 370                                                     "kludgeACLredactedattribute");
 371                 }
 372         }
 373
 374         ret = ldb_build_search_req_ex(&down_req,
 375                                         module->ldb, ac,
 376                                         req->op.search.base,
 377                                         req->op.search.scope,
 378                                         req->op.search.tree,
 379                                         attrs,
 380                                         req->controls,
 381                                         ac, kludge_acl_callback,
 382                                         req);
 383         if (ret != LDB_SUCCESS) {
 384                 return LDB_ERR_OPERATIONS_ERROR;
 385         }
 386
 387         /* check if there's an SD_FLAGS control */
 388         sd_control = ldb_request_get_control(down_req, LDB_CONTROL_SD_FLAGS_OID);
 389         if (sd_control) {
 390                 /* save it locally and remove it from the list */
 391                 /* we do not need to replace them later as we
 392                  * are keeping the original req intact */
 393                 if (!save_controls(sd_control, down_req, &sd_saved_controls)) {
 394                         return LDB_ERR_OPERATIONS_ERROR;
 395                 }
 396         }
 397
 398         /* perform the search */
 399         return ldb_next_request(module, down_req);
 400 }
 401
 402 /* ANY change type */
 403 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 404 {
 405         enum security_user_level user_type = what_is_user(module);
 406         switch (user_type) {
 407         case SECURITY_SYSTEM:
 408         case SECURITY_ADMINISTRATOR:
 409                 return ldb_next_request(module, req);
 410         default:
 411                 ldb_asprintf_errstring(module->ldb,
 412                                        "kludge_acl_change: "
 413                                        "attempted database modify not permitted. "
 414                                        "User %s is not SYSTEM or an administrator",
 415                                        user_name(req, module));
 416                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 417         }
 418 }
 419
 420 static int kludge_acl_extended(struct ldb_module *module, struct ldb_request *req)
 421 {
 422         enum security_user_level user_type;
 423
 424         /* allow everybody to read the sequence number */
 425         if (strcmp(req->op.extended.oid,
 426                    LDB_EXTENDED_SEQUENCE_NUMBER) == 0) {
 427                 return ldb_next_request(module, req);
 428         }
 429
 430         user_type = what_is_user(module);
 431
 432         switch (user_type) {
 433         case SECURITY_SYSTEM:
 434         case SECURITY_ADMINISTRATOR:
 435                 return ldb_next_request(module, req);
 436         default:
 437                 ldb_asprintf_errstring(module->ldb,
 438                                        "kludge_acl_change: "
 439                                        "attempted database modify not permitted. "
 440                                        "User %s is not SYSTEM or an administrator",
 441                                        user_name(req, module));
 442                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 443         }
 444 }
 445
 446 static int kludge_acl_init(struct ldb_module *module)
 447 {
 448         int ret, i;
 449         TALLOC_CTX *mem_ctx = talloc_new(module);
 450         static const char *attrs[] = { "passwordAttribute", NULL };
 451         struct ldb_result *res;
 452         struct ldb_message *msg;
 453         struct ldb_message_element *password_attributes;
 454
 455         struct kludge_private_data *data;
 456
 457         data = talloc(module, struct kludge_private_data);
 458         if (data == NULL) {
 459                 ldb_oom(module->ldb);
 460                 return LDB_ERR_OPERATIONS_ERROR;
 461         }
 462
 463         data->password_attrs = NULL;
 464         module->private_data = data;
 465
 466         if (!mem_ctx) {
 467                 ldb_oom(module->ldb);
 468                 return LDB_ERR_OPERATIONS_ERROR;
 469         }
 470
 471         ret = ldb_search(module->ldb, mem_ctx, &res,
 472                          ldb_dn_new(mem_ctx, module->ldb, "@KLUDGEACL"),
 473                          LDB_SCOPE_BASE, attrs, NULL);
 474         if (ret != LDB_SUCCESS) {
 475                 goto done;
 476         }
 477         if (res->count == 0) {
 478                 goto done;
 479         }
 480
 481         if (res->count > 1) {
 482                 talloc_free(mem_ctx);
 483                 return LDB_ERR_CONSTRAINT_VIOLATION;
 484         }
 485
 486         msg = res->msgs[0];
 487
 488         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 489         if (!password_attributes) {
 490                 goto done;
 491         }
 492         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 493         if (!data->password_attrs) {
 494                 talloc_free(mem_ctx);
 495                 ldb_oom(module->ldb);
 496                 return LDB_ERR_OPERATIONS_ERROR;
 497         }
 498         for (i=0; i < password_attributes->num_values; i++) {
 499                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 500                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 501         }
 502         data->password_attrs[i] = NULL;
 503
 504         ret = ldb_mod_register_control(module, LDB_CONTROL_SD_FLAGS_OID);
 505         if (ret != LDB_SUCCESS) {
 506                 ldb_debug(module->ldb, LDB_DEBUG_ERROR,
 507                         "partition: Unable to register control with rootdse!\n");
 508                 return LDB_ERR_OPERATIONS_ERROR;
 509         }
 510
 511 done:
 512         talloc_free(mem_ctx);
 513         return ldb_next_init(module);
 514 }
 515
 516 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 517         .name              = "kludge_acl",
 518         .search            = kludge_acl_search,
 519         .add               = kludge_acl_change,
 520         .modify            = kludge_acl_change,
 521         .del               = kludge_acl_change,
 522         .rename            = kludge_acl_change,
 523         .extended          = kludge_acl_extended,
 524         .init_context      = kludge_acl_init
 525 };