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);
  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                 ldb_oom(ldb);
 119                 return LDB_ERR_OPERATIONS_ERROR;
 120         }
 121
 122         /* To ensure that oc_el is valid, we must look for it after
 123            we alter the element array in ldb_msg_add_empty() */
 124         oc_el = ldb_msg_find_element(msg, "objectClass");
 125
 126         attr_list = dsdb_full_attribute_list(mem_ctx, schema, oc_el, DSDB_SCHEMA_ALL);
 127         if (!attr_list) {
 128                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 129                 talloc_free(mem_ctx);
 130                 return LDB_ERR_OPERATIONS_ERROR;
 131         }
 132
 133         for (i=0; attr_list && attr_list[i]; i++) {
 134                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 135         }
 136         talloc_free(mem_ctx);
 137         return LDB_SUCCESS;
 138
 139 }
 140 /* read all objectClasses */
 141
 142 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 143                                    const char *attrName)
 144 {
 145         struct ldb_message_element *oc_el;
 146         struct ldb_message_element *allowedClasses;
 147
 148         /* We need to ensure that the strings returned are valid for as long as the msg is valid */
 149         const struct dsdb_schema *schema = dsdb_get_schema(ldb, msg);
 150         const struct dsdb_class *sclass;
 151         unsigned int i, j;
 152         int ret;
 153
 154         /* If we don't have a schema yet, we can't do anything... */
 155         if (schema == NULL) {
 156                 return LDB_SUCCESS;
 157         }
 158
 159         /* Must remove any existing attribute, or else confusion reins */
 160         ldb_msg_remove_attr(msg, attrName);
 161         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 162         if (ret != LDB_SUCCESS) {
 163                 return ret;
 164         }
 165
 166         /* To ensure that oc_el is valid, we must look for it after
 167            we alter the element array in ldb_msg_add_empty() */
 168         oc_el = ldb_msg_find_element(msg, "objectClass");
 169
 170         for (i=0; oc_el && i < oc_el->num_values; i++) {
 171                 sclass = dsdb_class_by_lDAPDisplayName_ldb_val(schema, &oc_el->values[i]);
 172                 if (!sclass) {
 173                         /* We don't know this class?  what is going on? */
 174                         continue;
 175                 }
 176
 177                 for (j=0; sclass->possibleInferiors && sclass->possibleInferiors[j]; j++) {
 178                         ldb_msg_add_string(msg, attrName, sclass->possibleInferiors[j]);
 179                 }
 180         }
 181
 182         if (allowedClasses->num_values > 1) {
 183                 TYPESAFE_QSORT(allowedClasses->values, allowedClasses->num_values, data_blob_cmp);
 184
 185                 for (i=1 ; i < allowedClasses->num_values; i++) {
 186
 187                         struct ldb_val *val1 = &allowedClasses->values[i-1];
 188                         struct ldb_val *val2 = &allowedClasses->values[i];
 189                         if (data_blob_cmp(val1, val2) == 0) {
 190                                 memmove(val1, val2, (allowedClasses->num_values - i) * sizeof( struct ldb_val));
 191                                 allowedClasses->num_values--;
 192                                 i--;
 193                         }
 194                 }
 195         }
 196
 197         return LDB_SUCCESS;
 198 }
 199
 200 /* find all attributes allowed by all these objectClasses */
 201
 202 static int kludge_acl_callback(struct ldb_request *req, struct ldb_reply *ares)
 203 {
 204         struct ldb_context *ldb;
 205         struct kludge_acl_context *ac;
 206         struct kludge_private_data *data;
 207         unsigned int i;
 208         int ret;
 209
 210         ac = talloc_get_type(req->context, struct kludge_acl_context);
 211         data = talloc_get_type(ldb_module_get_private(ac->module), struct kludge_private_data);
 212         ldb = ldb_module_get_ctx(ac->module);
 213
 214         if (!ares) {
 215                 return ldb_module_done(ac->req, NULL, NULL,
 216                                         LDB_ERR_OPERATIONS_ERROR);
 217         }
 218         if (ares->error != LDB_SUCCESS) {
 219                 return ldb_module_done(ac->req, ares->controls,
 220                                         ares->response, ares->error);
 221         }
 222
 223         switch (ares->type) {
 224         case LDB_REPLY_ENTRY:
 225                 if (ac->allowedAttributes) {
 226                         ret = kludge_acl_allowedAttributes(ldb,
 227                                                    ares->message,
 228                                                    "allowedAttributes");
 229                         if (ret != LDB_SUCCESS) {
 230                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 231                         }
 232                 }
 233                 if (ac->allowedChildClasses) {
 234                         ret = kludge_acl_childClasses(ldb,
 235                                                 ares->message,
 236                                                 "allowedChildClasses");
 237                         if (ret != LDB_SUCCESS) {
 238                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 239                         }
 240                 }
 241
 242                 if (data && data->password_attrs) /* if we are not initialized just get through */
 243                 {
 244                         switch (ac->user_type) {
 245                         case SECURITY_SYSTEM:
 246                                 if (ac->allowedAttributesEffective) {
 247                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 248                                                                         "allowedAttributesEffective");
 249                                         if (ret != LDB_SUCCESS) {
 250                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 251                                         }
 252                                 }
 253                                 if (ac->allowedChildClassesEffective) {
 254                                         ret = kludge_acl_childClasses(ldb, ares->message,
 255                                                                         "allowedChildClassesEffective");
 256                                         if (ret != LDB_SUCCESS) {
 257                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 258                                         }
 259                                 }
 260                                 break;
 261
 262                         case SECURITY_ADMINISTRATOR:
 263                                 if (ac->allowedAttributesEffective) {
 264                                         ret = kludge_acl_allowedAttributes(ldb, ares->message,
 265                                                                         "allowedAttributesEffective");
 266                                         if (ret != LDB_SUCCESS) {
 267                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 268                                         }
 269                                 }
 270                                 if (ac->allowedChildClassesEffective) {
 271                                         ret = kludge_acl_childClasses(ldb, ares->message,
 272                                                                         "allowedChildClassesEffective");
 273                                         if (ret != LDB_SUCCESS) {
 274                                                 return ldb_module_done(ac->req, NULL, NULL, ret);
 275                                         }
 276                                 }
 277                                 /* fall through */
 278                         default:
 279                                 /* remove password attributes */
 280                                 for (i = 0; data->password_attrs[i]; i++) {
 281                                         ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 282                                 }
 283                         }
 284                 }
 285
 286                 if (ac->allowedAttributes ||
 287                     ac->allowedAttributesEffective ||
 288                     ac->allowedChildClasses ||
 289                     ac->allowedChildClassesEffective) {
 290
 291                         if (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 292                             !ldb_attr_in_list(ac->attrs, "*")) {
 293
 294                                 ldb_msg_remove_attr(ares->message,
 295                                                     "objectClass");
 296                         }
 297                 }
 298
 299                 return ldb_module_send_entry(ac->req, ares->message, ares->controls);
 300
 301         case LDB_REPLY_REFERRAL:
 302                 return ldb_module_send_referral(ac->req, ares->referral);
 303
 304         case LDB_REPLY_DONE:
 305                 return ldb_module_done(ac->req, ares->controls,
 306                                         ares->response, LDB_SUCCESS);
 307
 308         }
 309         return LDB_SUCCESS;
 310 }
 311
 312 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 313 {
 314         struct ldb_context *ldb;
 315         struct kludge_acl_context *ac;
 316         struct ldb_request *down_req;
 317         struct kludge_private_data *data;
 318         const char * const *attrs;
 319         int ret;
 320         unsigned int i;
 321
 322         ldb = ldb_module_get_ctx(module);
 323
 324         ac = talloc(req, struct kludge_acl_context);
 325         if (ac == NULL) {
 326                 ldb_oom(ldb);
 327                 return LDB_ERR_OPERATIONS_ERROR;
 328         }
 329
 330         data = talloc_get_type(ldb_module_get_private(module), struct kludge_private_data);
 331
 332         if (data && data->acl_perform)
 333                 return ldb_next_request(module, req);
 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                                         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 ret;
 385         }
 386
 387         /* perform the search */
 388         return ldb_next_request(module, down_req);
 389 }
 390
 391 /* ANY change type */
 392 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 393 {
 394         struct ldb_context *ldb = ldb_module_get_ctx(module);
 395         enum security_user_level user_type = what_is_user(module);
 396         struct kludge_private_data *data = talloc_get_type(ldb_module_get_private(module),
 397                                                            struct kludge_private_data);
 398
 399         if (data->acl_perform)
 400                 return ldb_next_request(module, req);
 401
 402         switch (user_type) {
 403         case SECURITY_SYSTEM:
 404         case SECURITY_ADMINISTRATOR:
 405                 return ldb_next_request(module, req);
 406         default:
 407                 ldb_asprintf_errstring(ldb,
 408                                        "kludge_acl_change: "
 409                                        "attempted database modify not permitted. "
 410                                        "User %s is not SYSTEM or an administrator",
 411                                        user_name(req, module));
 412                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 413         }
 414 }
 415
 416 static int kludge_acl_extended(struct ldb_module *module, struct ldb_request *req)
 417 {
 418         struct ldb_context *ldb = ldb_module_get_ctx(module);
 419         enum security_user_level user_type;
 420
 421         /* allow everybody to read the sequence number */
 422         if (strcmp(req->op.extended.oid,
 423                    LDB_EXTENDED_SEQUENCE_NUMBER) == 0) {
 424                 return ldb_next_request(module, req);
 425         }
 426
 427         user_type = what_is_user(module);
 428
 429         switch (user_type) {
 430         case SECURITY_SYSTEM:
 431         case SECURITY_ADMINISTRATOR:
 432                 return ldb_next_request(module, req);
 433         default:
 434                 ldb_asprintf_errstring(ldb,
 435                                        "kludge_acl_change: "
 436                                        "attempted database modify not permitted. "
 437                                        "User %s is not SYSTEM or an administrator",
 438                                        user_name(req, module));
 439                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 440         }
 441 }
 442
 443 static int kludge_acl_init(struct ldb_module *module)
 444 {
 445         struct ldb_context *ldb;
 446         int ret;
 447         unsigned int i;
 448         TALLOC_CTX *mem_ctx = talloc_new(module);
 449         static const char *attrs[] = { "passwordAttribute", NULL };
 450         struct ldb_result *res;
 451         struct ldb_message *msg;
 452         struct ldb_message_element *password_attributes;
 453
 454         struct kludge_private_data *data;
 455
 456         ldb = ldb_module_get_ctx(module);
 457
 458         data = talloc(module, struct kludge_private_data);
 459         if (data == NULL) {
 460                 ldb_oom(ldb);
 461                 return LDB_ERR_OPERATIONS_ERROR;
 462         }
 463
 464         data->password_attrs = NULL;
 465         data->acl_perform = lp_parm_bool(ldb_get_opaque(ldb, "loadparm"),
 466                                          NULL, "acl", "perform", false);
 467         ldb_module_set_private(module, data);
 468
 469         if (!mem_ctx) {
 470                 ldb_oom(ldb);
 471                 return LDB_ERR_OPERATIONS_ERROR;
 472         }
 473
 474         ret = ldb_search(ldb, mem_ctx, &res,
 475                          ldb_dn_new(mem_ctx, ldb, "@KLUDGEACL"),
 476                          LDB_SCOPE_BASE, attrs, NULL);
 477         if (ret != LDB_SUCCESS) {
 478                 goto done;
 479         }
 480         if (res->count == 0) {
 481                 goto done;
 482         }
 483
 484         if (res->count > 1) {
 485                 talloc_free(mem_ctx);
 486                 return LDB_ERR_CONSTRAINT_VIOLATION;
 487         }
 488
 489         msg = res->msgs[0];
 490
 491         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 492         if (!password_attributes) {
 493                 goto done;
 494         }
 495         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 496         if (!data->password_attrs) {
 497                 talloc_free(mem_ctx);
 498                 ldb_oom(ldb);
 499                 return LDB_ERR_OPERATIONS_ERROR;
 500         }
 501         for (i=0; i < password_attributes->num_values; i++) {
 502                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 503                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 504         }
 505         data->password_attrs[i] = NULL;
 506
 507 done:
 508         talloc_free(mem_ctx);
 509         return ldb_next_init(module);
 510 }
 511
 512 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 513         .name              = "kludge_acl",
 514 /*      .search            = kludge_acl_search,
 515         .add               = kludge_acl_change,
 516         .modify            = kludge_acl_change,
 517         .del               = kludge_acl_change,
 518         .rename            = kludge_acl_change, */
 519         .extended          = kludge_acl_extended,
 520         .init_context      = kludge_acl_init
 521 };