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 #include "lib/util/tsort.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         bool acl_perform;
  52 };
  53
  54 static enum security_user_level what_is_user(struct ldb_module *module)
  55 {
  56         struct ldb_context *ldb = ldb_module_get_ctx(module);
  57         struct auth_session_info *session_info
  58                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  59         return security_session_user_level(session_info, NULL);
  60 }
  61
  62 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  63 {
  64         struct ldb_context *ldb = ldb_module_get_ctx(module);
  65         struct auth_session_info *session_info
  66                 = (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
  67         if (!session_info) {
  68                 return "UNKNOWN (NULL)";
  69         }
  70
  71         return talloc_asprintf(mem_ctx, "%s\\%s",
  72                                session_info->server_info->domain_name,
  73                                session_info->server_info->account_name);
  74 }
  75
  76 /* search */
  77 struct kludge_acl_context {
  78
  79         struct ldb_module *module;
  80         struct ldb_request *req;
  81
  82         enum security_user_level user_type;
  83         bool allowedAttributes;
  84         bool allowedAttributesEffective;
  85         bool allowedChildClasses;
  86         bool allowedChildClassesEffective;
  87         const char * const *attrs;
  88 };
  89
  90 /* read all objectClasses */
  91
  92 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
  93                                         const char *attrName)
  94 {
  95         struct ldb_message_element *oc_el;
  96         struct ldb_message_element *allowedAttributes;
  97         /* We need to ensure that the strings returned are valid for as long as the msg is valid */
  98         const struct dsdb_schema *schema = dsdb_get_schema(ldb, msg);
  99         TALLOC_CTX *mem_ctx;
 100         const char **attr_list;
 101         unsigned int i;
 102         int ret;
 103
 104         /* If we don't have a schema yet, we can't do anything... */
 105         if (schema == NULL) {
 106                 return LDB_SUCCESS;
 107         }
 108
 109         /* Must remove any existing attribute, or else confusion reins */
 110         ldb_msg_remove_attr(msg, attrName);
 111         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 112         if (ret != LDB_SUCCESS) {
 113                 return ret;
 114         }
 115
 116         mem_ctx = talloc_new(msg);
 117         if (!mem_ctx) {
 118                 return ldb_oom(ldb);
 119         }
 120
 121         /* To ensure that oc_el is valid, we must look for it after
 122            we alter the element array in ldb_msg_add_empty() */
 123         oc_el = ldb_msg_find_element(msg, "objectClass");
 124
 125         attr_list = dsdb_full_attribute_list(mem_ctx, schema, oc_el, DSDB_SCHEMA_ALL);
 126         if (!attr_list) {
 127                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 128                 talloc_free(mem_ctx);
 129                 return LDB_ERR_OPERATIONS_ERROR;
 130         }
 131
 132         for (i=0; attr_list && attr_list[i]; i++) {
 133                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 134         }
 135         talloc_free(mem_ctx);
 136         return LDB_SUCCESS;
 137
 138 }
 139 /* read all objectClasses */
 140
 141 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 142                                    const char *attrName)
 143 {
 144         struct ldb_message_element *oc_el;
 145         struct ldb_message_element *allowedClasses;
 146
 147         /* We need to ensure that the strings returned are valid for as long as the msg is valid */
 148         const struct dsdb_schema *schema = dsdb_get_schema(ldb, msg);
 149         const struct dsdb_class *sclass;
 150         unsigned int i, j;
 151         int ret;
 152
 153         /* If we don't have a schema yet, we can't do anything... */
 154         if (schema == NULL) {
 155                 return LDB_SUCCESS;
 156         }
 157
 158         /* Must remove any existing attribute, or else confusion reins */
 159         ldb_msg_remove_attr(msg, attrName);
 160         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 161         if (ret != LDB_SUCCESS) {
 162                 return ret;
 163         }
 164
 165         /* To ensure that oc_el is valid, we must look for it after
 166            we alter the element array in ldb_msg_add_empty() */
 167         oc_el = ldb_msg_find_element(msg, "objectClass");
 168
 169         for (i=0; oc_el && i < oc_el->num_values; i++) {
 170                 sclass = dsdb_class_by_lDAPDisplayName_ldb_val(schema, &oc_el->values[i]);
 171                 if (!sclass) {
 172                         /* We don't know this class?  what is going on? */
 173                         continue;
 174                 }
 175
 176                 for (j=0; sclass->possibleInferiors && sclass->possibleInferiors[j]; j++) {
 177                         ldb_msg_add_string(msg, attrName, sclass->possibleInferiors[j]);
 178                 }
 179         }
 180
 181         if (allowedClasses->num_values > 1) {
 182                 TYPESAFE_QSORT(allowedClasses->values, allowedClasses->num_values, data_blob_cmp);
 183
 184                 for (i=1 ; i < allowedClasses->num_values; i++) {
 185
 186                         struct ldb_val *val1 = &allowedClasses->values[i-1];
 187                         struct ldb_val *val2 = &allowedClasses->values[i];
 188                         if (data_blob_cmp(val1, val2) == 0) {
 189                                 memmove(val1, val2, (allowedClasses->num_values - i) * sizeof( struct ldb_val));
 190                                 allowedClasses->num_values--;
 191                                 i--;
 192                         }
 193                 }
 194         }
 195
 196         return LDB_SUCCESS;
 197 }
 198
 199 /* find all attributes allowed by all these objectClasses */
 200
 201 static int kludge_acl_callback(struct ldb_request *req, struct ldb_reply *ares)
 202 {
 203         struct ldb_context *ldb;
 204         struct kludge_acl_context *ac;
 205         struct kludge_private_data *data;
 206         unsigned int i;
 207         int ret;
 208
 209         ac = talloc_get_type(req->context, struct kludge_acl_context);
 210         data = talloc_get_type(ldb_module_get_private(ac->module), struct kludge_private_data);
 211         ldb = ldb_module_get_ctx(ac->module);
 212
 213         if (!ares) {
 214                 return ldb_module_done(ac->req, NULL, NULL,
 215                                         LDB_ERR_OPERATIONS_ERROR);
 216         }
 217         if (ares->error != LDB_SUCCESS) {
 218                 return ldb_module_done(ac->req, ares->controls,
 219                                         ares->response, ares->error);
 220         }
 221
 222         switch (ares->type) {
 223         case LDB_REPLY_ENTRY:
 224                 if (ac->allowedAttributes) {
 225                         ret = kludge_acl_allowedAttributes(ldb,
 226                                                    ares->message,
 227                                                    "allowedAttributes");
 228                         if (ret != LDB_SUCCESS) {
 229                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 230                         }
 231                 }
 232                 if (ac->allowedChildClasses) {
 233                         ret = kludge_acl_childClasses(ldb,
 234                                                 ares->message,
 235                                                 "allowedChildClasses");
 236                         if (ret != LDB_SUCCESS) {
 237                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 238                         }
 239                 }
 240
 241                 if (data && data->password_attrs) /* if we are not initialized just get through */
 242                 {
 243                         switch (ac->user_type) {
 244                         case SECURITY_SYSTEM:
 245                                 if (ac->allowedAttributesEffective) {
 246                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 247                                                                         "allowedAttributesEffective");
 248                                         if (ret != LDB_SUCCESS) {
 249                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 250                                         }
 251                                 }
 252                                 if (ac->allowedChildClassesEffective) {
 253                                         ret = kludge_acl_childClasses(ldb, ares->message,
 254                                                                         "allowedChildClassesEffective");
 255                                         if (ret != LDB_SUCCESS) {
 256                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 257                                         }
 258                                 }
 259                                 break;
 260
 261                         case SECURITY_ADMINISTRATOR:
 262                                 if (ac->allowedAttributesEffective) {
 263                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 264                                                                         "allowedAttributesEffective");
 265                                         if (ret != LDB_SUCCESS) {
 266                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 267                                         }
 268                                 }
 269                                 if (ac->allowedChildClassesEffective) {
 270                                         ret = kludge_acl_childClasses(ldb, ares->message,
 271                                                                         "allowedChildClassesEffective");
 272                                         if (ret != LDB_SUCCESS) {
 273                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 274                                         }
 275                                 }
 276                                 /* fall through */
 277                         default:
 278                                 /* remove password attributes */
 279                                 for (i = 0; data->password_attrs[i]; i++) {
 280                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 281                                 }
 282                         }
 283                 }
 284
 285                 if (ac->allowedAttributes ||
 286                     ac->allowedAttributesEffective ||
 287                     ac->allowedChildClasses ||
 288                     ac->allowedChildClassesEffective) {
 289
 290                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 291                             !ldb_attr_in_list(ac->attrs, "*")) {
 292
 293                                 ldb_msg_remove_attr(ares->message,
 294                                                     "objectClass");
 295                         }
 296                 }
 297
 298                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 299
 300         case LDB_REPLY_REFERRAL:
 301                 return ldb_module_send_referral(ac->req, ares->referral);
 302
 303         case LDB_REPLY_DONE:
 304                 return ldb_module_done(ac->req, ares->controls,
 305                                         ares->response, LDB_SUCCESS);
 306
 307         }
 308         return LDB_SUCCESS;
 309 }
 310
 311 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 312 {
 313         struct ldb_context *ldb;
 314         struct kludge_acl_context *ac;
 315         struct ldb_request *down_req;
 316         struct kludge_private_data *data;
 317         const char * const *attrs;
 318         int ret;
 319         unsigned int i;
 320
 321         ldb = ldb_module_get_ctx(module);
 322
 323         ac = talloc(req, struct kludge_acl_context);
 324         if (ac == NULL) {
 325                 return ldb_oom(ldb);
 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         /* perform the search */
 386         return ldb_next_request(module, down_req);
 387 }
 388
 389 /* ANY change type */
 390 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 391 {
 392         struct ldb_context *ldb = ldb_module_get_ctx(module);
 393         enum security_user_level user_type = what_is_user(module);
 394         struct kludge_private_data *data = talloc_get_type(ldb_module_get_private(module),
 395                                                            struct kludge_private_data);
 396
 397         if (data->acl_perform)
 398                 return ldb_next_request(module, req);
 399
 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;
 445         unsigned int i;
 446         TALLOC_CTX *mem_ctx = talloc_new(module);
 447         static const char *attrs[] = { "passwordAttribute", NULL };
 448         struct ldb_result *res;
 449         struct ldb_message *msg;
 450         struct ldb_message_element *password_attributes;
 451
 452         struct kludge_private_data *data;
 453
 454         ldb = ldb_module_get_ctx(module);
 455
 456         data = talloc(module, struct kludge_private_data);
 457         if (data == NULL) {
 458                 return ldb_oom(ldb);
 459         }
 460
 461         data->password_attrs = NULL;
 462         data->acl_perform = lpcfg_parm_bool(ldb_get_opaque(ldb, "loadparm"),
 463                                          NULL, "acl", "perform", false);
 464         ldb_module_set_private(module, data);
 465
 466         if (!mem_ctx) {
 467                 return ldb_oom(ldb);
 468         }
 469
 470         ret = ldb_search(ldb, mem_ctx, &res,
 471                          ldb_dn_new(mem_ctx, ldb, "@KLUDGEACL"),
 472                          LDB_SCOPE_BASE, attrs, NULL);
 473         if (ret != LDB_SUCCESS) {
 474                 goto done;
 475         }
 476         if (res->count == 0) {
 477                 goto done;
 478         }
 479
 480         if (res->count > 1) {
 481                 talloc_free(mem_ctx);
 482                 return LDB_ERR_CONSTRAINT_VIOLATION;
 483         }
 484
 485         msg = res->msgs[0];
 486
 487         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 488         if (!password_attributes) {
 489                 goto done;
 490         }
 491         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 492         if (!data->password_attrs) {
 493                 talloc_free(mem_ctx);
 494                 return ldb_oom(ldb);
 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 done:
 503         talloc_free(mem_ctx);
 504         return ldb_next_init(module);
 505 }
 506
 507 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 508         .name              = "kludge_acl",
 509 /*      .search            = kludge_acl_search,
 510         .add               = kludge_acl_change,
 511         .modify            = kludge_acl_change,
 512         .del               = kludge_acl_change,
 513         .rename            = kludge_acl_change, */
 514         .extended          = kludge_acl_extended,
 515         .init_context      = kludge_acl_init
 516 };