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
   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         void *up_context;
  78         int (*up_callback)(struct ldb_context *, void *, struct ldb_reply *);
  79
  80         enum security_user_level user_type;
  81         bool allowedAttributes;
  82         bool allowedAttributesEffective;
  83         bool allowedChildClasses;
  84         bool allowedChildClassesEffective;
  85         const char **attrs;
  86 };
  87
  88 /* read all objectClasses */
  89
  90 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
  91                                         const char *attrName)
  92 {
  93         struct ldb_message_element *oc_el;
  94         struct ldb_message_element *allowedAttributes;
  95         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
  96         TALLOC_CTX *mem_ctx;
  97         char **objectclass_list, **attr_list;
  98         int i, ret;
  99
 100         /* If we don't have a schema yet, we can't do anything... */
 101         if (schema == NULL) {
 102                 return LDB_SUCCESS;
 103         }
 104
 105         /* Must remove any existing attribute, or else confusion reins */
 106         ldb_msg_remove_attr(msg, attrName);
 107         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 108         if (ret != LDB_SUCCESS) {
 109                 return ret;
 110         }
 111
 112         mem_ctx = talloc_new(msg);
 113         if (!mem_ctx) {
 114                 ldb_oom(ldb);
 115                 return LDB_ERR_OPERATIONS_ERROR;
 116         }
 117
 118         /* To ensure that oc_el is valid, we must look for it after
 119            we alter the element array in ldb_msg_add_empty() */
 120         oc_el = ldb_msg_find_element(msg, "objectClass");
 121
 122         objectclass_list = talloc_array(mem_ctx, char *, oc_el->num_values + 1);
 123         if (!objectclass_list) {
 124                 ldb_oom(ldb);
 125                 talloc_free(mem_ctx);
 126                 return LDB_ERR_OPERATIONS_ERROR;
 127         }
 128
 129         for (i=0; oc_el && i < oc_el->num_values; i++) {
 130                 objectclass_list[i] = (char *)oc_el->values[i].data;
 131         }
 132         objectclass_list[i] = NULL;
 133
 134         attr_list = dsdb_full_attribute_list(mem_ctx, schema, (const char **)objectclass_list, DSDB_SCHEMA_ALL);
 135         if (!attr_list) {
 136                 ldb_asprintf_errstring(ldb, "kludge_acl: Failed to get list of attributes create %s attribute", attrName);
 137                 talloc_free(mem_ctx);
 138                 return LDB_ERR_OPERATIONS_ERROR;
 139         }
 140
 141         for (i=0; attr_list && attr_list[i]; i++) {
 142                 ldb_msg_add_string(msg, attrName, attr_list[i]);
 143         }
 144         talloc_free(mem_ctx);
 145         return LDB_SUCCESS;
 146
 147 }
 148 /* read all objectClasses */
 149
 150 static int kludge_acl_childClasses(struct ldb_context *ldb, struct ldb_message *msg,
 151                                    const char *attrName)
 152 {
 153         struct ldb_message_element *oc_el;
 154         struct ldb_message_element *allowedClasses;
 155         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 156         const struct dsdb_class *class;
 157         int i, j, ret;
 158
 159         /* If we don't have a schema yet, we can't do anything... */
 160         if (schema == NULL) {
 161                 return LDB_SUCCESS;
 162         }
 163
 164         /* Must remove any existing attribute, or else confusion reins */
 165         ldb_msg_remove_attr(msg, attrName);
 166         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedClasses);
 167         if (ret != LDB_SUCCESS) {
 168                 return ret;
 169         }
 170
 171         /* To ensure that oc_el is valid, we must look for it after
 172            we alter the element array in ldb_msg_add_empty() */
 173         oc_el = ldb_msg_find_element(msg, "objectClass");
 174
 175         for (i=0; oc_el && i < oc_el->num_values; i++) {
 176                 class = dsdb_class_by_lDAPDisplayName(schema, (const char *)oc_el->values[i].data);
 177                 if (!class) {
 178                         /* We don't know this class?  what is going on? */
 179                         continue;
 180                 }
 181
 182                 for (j=0; class->possibleInferiors && class->possibleInferiors[j]; j++) {
 183                         ldb_msg_add_string(msg, attrName, class->possibleInferiors[j]);
 184                 }
 185         }
 186
 187         if (allowedClasses->num_values > 1) {
 188                 qsort(allowedClasses->values,
 189                       allowedClasses->num_values,
 190                       sizeof(*allowedClasses->values),
 191                       (comparison_fn_t)data_blob_cmp);
 192
 193                 for (i=1 ; i < allowedClasses->num_values; i++) {
 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_context *ldb, void *context, 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(context, struct kludge_acl_context);
 217         data = talloc_get_type(ac->module->private_data, struct kludge_private_data);
 218
 219         if (ares->type != LDB_REPLY_ENTRY) {
 220                 return ac->up_callback(ldb, ac->up_context, ares);
 221         }
 222
 223         if (ac->allowedAttributes) {
 224                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributes");
 225                 if (ret != LDB_SUCCESS) {
 226                         return ret;
 227
 228                 }
 229         }
 230         if (ac->allowedChildClasses) {
 231                 ret = kludge_acl_childClasses(ldb, ares->message, "allowedChildClasses");
 232                 if (ret != LDB_SUCCESS) {
 233                         return ret;
 234                 }
 235         }
 236
 237         if (data && data->password_attrs) /* if we are not initialized just get through */
 238         {
 239                 switch (ac->user_type) {
 240                 case SECURITY_SYSTEM:
 241                         if (ac->allowedAttributesEffective) {
 242                                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributesEffective");
 243                                 if (ret != LDB_SUCCESS) {
 244                                         return ret;
 245                                 }
 246                         }
 247                         if (ac->allowedChildClassesEffective) {
 248                                 ret = kludge_acl_childClasses(ldb, ares->message, "allowedChildClassesEffective");
 249                                 if (ret != LDB_SUCCESS) {
 250                                         return ret;
 251                                 }
 252                         }
 253                         break;
 254                 case SECURITY_ADMINISTRATOR:
 255                         if (ac->allowedAttributesEffective) {
 256                                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributesEffective");
 257                                 if (ret != LDB_SUCCESS) {
 258                                         return ret;
 259                                 }
 260                         }
 261                         if (ac->allowedChildClassesEffective) {
 262                                 ret = kludge_acl_childClasses(ldb, ares->message, "allowedChildClassesEffective");
 263                                 if (ret != LDB_SUCCESS) {
 264                                         return ret;
 265                                 }
 266                         }
 267                         /* fall though */
 268                 default:
 269                         /* remove password attributes */
 270                         for (i = 0; data->password_attrs[i]; i++) {
 271                                 ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 272                         }
 273                 }
 274         }
 275
 276         if ((ac->allowedAttributes || ac->allowedAttributesEffective
 277              || ac->allowedChildClasses || ac->allowedChildClassesEffective) &&
 278             (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 279              !ldb_attr_in_list(ac->attrs, "*"))) {
 280                 ldb_msg_remove_attr(ares->message, "objectClass");
 281         }
 282
 283         return ac->up_callback(ldb, ac->up_context, ares);
 284 }
 285
 286 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 287 {
 288         struct kludge_acl_context *ac;
 289         struct ldb_request *down_req;
 290         struct kludge_private_data *data;
 291         int ret, i;
 292
 293         req->handle = NULL;
 294
 295         ac = talloc(req, struct kludge_acl_context);
 296         if (ac == NULL) {
 297                 ldb_oom(module->ldb);
 298                 return LDB_ERR_OPERATIONS_ERROR;
 299         }
 300
 301         data = talloc_get_type(module->private_data, struct kludge_private_data);
 302
 303         ac->module = module;
 304         ac->up_context = req->context;
 305         ac->up_callback = req->callback;
 306         ac->user_type = what_is_user(module);
 307         ac->attrs = req->op.search.attrs;
 308
 309         down_req = talloc_zero(req, struct ldb_request);
 310         if (down_req == NULL) {
 311                 ldb_oom(module->ldb);
 312                 return LDB_ERR_OPERATIONS_ERROR;
 313         }
 314
 315         down_req->operation = req->operation;
 316         down_req->op.search.base = req->op.search.base;
 317         down_req->op.search.scope = req->op.search.scope;
 318         down_req->op.search.tree = req->op.search.tree;
 319         down_req->op.search.attrs = req->op.search.attrs;
 320
 321         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 322
 323         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 324
 325         ac->allowedChildClasses = ldb_attr_in_list(req->op.search.attrs, "allowedChildClasses");
 326
 327         ac->allowedChildClassesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedChildClassesEffective");
 328
 329         if (ac->allowedAttributes || ac->allowedAttributesEffective || ac->allowedChildClasses || ac->allowedChildClassesEffective) {
 330                 down_req->op.search.attrs
 331                         = ldb_attr_list_copy_add(down_req, down_req->op.search.attrs, "objectClass");
 332         }
 333
 334         /*  FIXME: I hink we should copy the tree and keep the original
 335          *  unmodified. SSS */
 336         /* replace any attributes in the parse tree that are private,
 337            so we don't allow a search for 'userPassword=penguin',
 338            just as we would not allow that attribute to be returned */
 339         switch (ac->user_type) {
 340         case SECURITY_SYSTEM:
 341                 break;
 342         default:
 343                 /* remove password attributes */
 344                 for (i = 0; data && data->password_attrs && data->password_attrs[i]; i++) {
 345                         ldb_parse_tree_attr_replace(down_req->op.search.tree,
 346                                                     data->password_attrs[i],
 347                                                     "kludgeACLredactedattribute");
 348                 }
 349         }
 350
 351         down_req->controls = req->controls;
 352
 353         down_req->context = ac;
 354         down_req->callback = kludge_acl_callback;
 355         ldb_set_timeout_from_prev_req(module->ldb, req, down_req);
 356
 357         /* perform the search */
 358         ret = ldb_next_request(module, down_req);
 359
 360         /* do not free down_req as the call results may be linked to it,
 361          * it will be freed when the upper level request get freed */
 362         if (ret == LDB_SUCCESS) {
 363                 req->handle = down_req->handle;
 364         }
 365
 366         return ret;
 367 }
 368
 369 /* ANY change type */
 370 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 371 {
 372         enum security_user_level user_type = what_is_user(module);
 373         switch (user_type) {
 374         case SECURITY_SYSTEM:
 375         case SECURITY_ADMINISTRATOR:
 376                 return ldb_next_request(module, req);
 377         default:
 378                 ldb_asprintf_errstring(module->ldb,
 379                                        "kludge_acl_change: "
 380                                        "attempted database modify not permitted. "
 381                                        "User %s is not SYSTEM or an administrator",
 382                                        user_name(req, module));
 383                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 384         }
 385 }
 386
 387 static int kludge_acl_init(struct ldb_module *module)
 388 {
 389         int ret, i;
 390         TALLOC_CTX *mem_ctx = talloc_new(module);
 391         static const char *attrs[] = { "passwordAttribute", NULL };
 392         struct ldb_result *res;
 393         struct ldb_message *msg;
 394         struct ldb_message_element *password_attributes;
 395
 396         struct kludge_private_data *data;
 397
 398         data = talloc(module, struct kludge_private_data);
 399         if (data == NULL) {
 400                 ldb_oom(module->ldb);
 401                 return LDB_ERR_OPERATIONS_ERROR;
 402         }
 403
 404         data->password_attrs = NULL;
 405         module->private_data = data;
 406
 407         if (!mem_ctx) {
 408                 ldb_oom(module->ldb);
 409                 return LDB_ERR_OPERATIONS_ERROR;
 410         }
 411
 412         ret = ldb_search(module->ldb, mem_ctx, &res,
 413                          ldb_dn_new(mem_ctx, module->ldb, "@KLUDGEACL"),
 414                          LDB_SCOPE_BASE, attrs, NULL);
 415         if (ret != LDB_SUCCESS) {
 416                 goto done;
 417         }
 418         if (res->count == 0) {
 419                 goto done;
 420         }
 421
 422         if (res->count > 1) {
 423                 talloc_free(mem_ctx);
 424                 return LDB_ERR_CONSTRAINT_VIOLATION;
 425         }
 426
 427         msg = res->msgs[0];
 428
 429         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 430         if (!password_attributes) {
 431                 goto done;
 432         }
 433         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 434         if (!data->password_attrs) {
 435                 talloc_free(mem_ctx);
 436                 ldb_oom(module->ldb);
 437                 return LDB_ERR_OPERATIONS_ERROR;
 438         }
 439         for (i=0; i < password_attributes->num_values; i++) {
 440                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 441                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 442         }
 443         data->password_attrs[i] = NULL;
 444
 445 done:
 446         talloc_free(mem_ctx);
 447         return ldb_next_init(module);
 448 }
 449
 450 _PUBLIC_ const struct ldb_module_ops ldb_kludge_acl_module_ops = {
 451         .name              = "kludge_acl",
 452         .search            = kludge_acl_search,
 453         .add               = kludge_acl_change,
 454         .modify            = kludge_acl_change,
 455         .del               = kludge_acl_change,
 456         .rename            = kludge_acl_change,
 457         .extended          = kludge_acl_change,
 458         .init_context      = kludge_acl_init
 459 };