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 enum user_is {
  50         ANONYMOUS,
  51         USER,
  52         ADMINISTRATOR,
  53         SYSTEM
  54 };
  55
  56 struct kludge_private_data {
  57         const char **password_attrs;
  58 };
  59
  60 static enum user_is what_is_user(struct ldb_module *module)
  61 {
  62         struct auth_session_info *session_info
  63                 = ldb_get_opaque(module->ldb, "sessionInfo");
  64         if (!session_info) {
  65                 return ANONYMOUS;
  66         }
  67
  68         if (security_token_is_system(session_info->security_token)) {
  69                 return SYSTEM;
  70         }
  71
  72         if (security_token_is_anonymous(session_info->security_token)) {
  73                 return ANONYMOUS;
  74         }
  75
  76         if (security_token_has_builtin_administrators(session_info->security_token)) {
  77                 return ADMINISTRATOR;
  78         }
  79
  80         if (security_token_has_nt_authenticated_users(session_info->security_token)) {
  81                 return USER;
  82         }
  83
  84         return ANONYMOUS;
  85 }
  86
  87 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  88 {
  89         struct auth_session_info *session_info
  90                 = ldb_get_opaque(module->ldb, "sessionInfo");
  91         if (!session_info) {
  92                 return "UNKNOWN (NULL)";
  93         }
  94
  95         return talloc_asprintf(mem_ctx, "%s\\%s",
  96                                session_info->server_info->domain_name,
  97                                session_info->server_info->account_name);
  98 }
  99
 100 /* search */
 101 struct kludge_acl_context {
 102
 103         struct ldb_module *module;
 104         void *up_context;
 105         int (*up_callback)(struct ldb_context *, void *, struct ldb_reply *);
 106
 107         enum user_is user_type;
 108         bool allowedAttributes;
 109         bool allowedAttributesEffective;
 110         const char **attrs;
 111 };
 112
 113 /* read all objectClasses */
 114
 115 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
 116                                                          const char *attrName)
 117 {
 118         struct ldb_message_element *oc_el = ldb_msg_find_element(msg, "objectClass");
 119         struct ldb_message_element *allowedAttributes;
 120         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 121         const struct dsdb_class *class;
 122         int i, j, ret;
 123         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 124         if (ret != LDB_SUCCESS) {
 125                 return ret;
 126         }
 127
 128         for (i=0; i < oc_el->num_values; i++) {
 129                 class = dsdb_class_by_lDAPDisplayName(schema, (const char *)oc_el->values[i].data);
 130                 if (!class) {
 131                         /* We don't know this class?  what is going on? */
 132                         continue;
 133                 }
 134                 for (j=0; class->mayContain && class->mayContain[j]; j++) {
 135                         ldb_msg_add_string(msg, attrName, class->mayContain[j]);
 136                 }
 137                 for (j=0; class->mustContain && class->mustContain[j]; j++) {
 138                         ldb_msg_add_string(msg, attrName, class->mustContain[j]);
 139                 }
 140                 for (j=0; class->systemMayContain && class->systemMayContain[j]; j++) {
 141                         ldb_msg_add_string(msg, attrName, class->systemMayContain[j]);
 142                 }
 143                 for (j=0; class->systemMustContain && class->systemMustContain[j]; j++) {
 144                         ldb_msg_add_string(msg, attrName, class->systemMustContain[j]);
 145                 }
 146         }
 147
 148         if (allowedAttributes->num_values > 1) {
 149                 qsort(allowedAttributes->values,
 150                       allowedAttributes->num_values,
 151                       sizeof(*allowedAttributes->values),
 152                       data_blob_cmp);
 153
 154                 for (i=1 ; i < allowedAttributes->num_values; i++) {
 155                         struct ldb_val *val1 = &allowedAttributes->values[i-1];
 156                         struct ldb_val *val2 = &allowedAttributes->values[i];
 157                         if (data_blob_cmp(val1, val2) == 0) {
 158                                 memmove(val1, val2, (allowedAttributes->num_values - i) * sizeof( struct ldb_val));
 159                                 allowedAttributes->num_values--;
 160                                 i--;
 161                         }
 162                 }
 163         }
 164
 165         return 0;
 166
 167 }
 168
 169 /* find all attributes allowed by all these objectClasses */
 170
 171 static int kludge_acl_callback(struct ldb_context *ldb, void *context, struct ldb_reply *ares)
 172 {
 173         struct kludge_acl_context *ac;
 174         struct kludge_private_data *data;
 175         int i, ret;
 176
 177         if (!context || !ares) {
 178                 ldb_set_errstring(ldb, "NULL Context or Result in callback");
 179                 goto error;
 180         }
 181
 182         ac = talloc_get_type(context, struct kludge_acl_context);
 183         data = talloc_get_type(ac->module->private_data, struct kludge_private_data);
 184
 185         if (ares->type != LDB_REPLY_ENTRY) {
 186                 return ac->up_callback(ldb, ac->up_context, ares);
 187         }
 188
 189         if (ac->allowedAttributes) {
 190                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributes");
 191                 if (ret != LDB_SUCCESS) {
 192                         return ret;
 193                 }
 194         }
 195
 196         if (data && data->password_attrs) /* if we are not initialized just get through */
 197         {
 198                 switch (ac->user_type) {
 199                 case SYSTEM:
 200                 case ADMINISTRATOR:
 201                         if (ac->allowedAttributesEffective) {
 202                                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributesEffective");
 203                                 if (ret != LDB_SUCCESS) {
 204                                         return ret;
 205                                 }
 206                         }
 207                         break;
 208                 default:
 209                         /* remove password attributes */
 210                         for (i = 0; data->password_attrs[i]; i++) {
 211                                 ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 212                         }
 213                 }
 214         }
 215
 216         if ((ac->allowedAttributes || ac->allowedAttributesEffective) &&
 217             (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 218              !ldb_attr_in_list(ac->attrs, "*"))) {
 219                 ldb_msg_remove_attr(ares->message, "objectClass");
 220         }
 221
 222         return ac->up_callback(ldb, ac->up_context, ares);
 223
 224 error:
 225         talloc_free(ares);
 226         return LDB_ERR_OPERATIONS_ERROR;
 227 }
 228
 229 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 230 {
 231         struct kludge_acl_context *ac;
 232         struct ldb_request *down_req;
 233         struct kludge_private_data *data;
 234         int ret, i;
 235
 236         req->handle = NULL;
 237
 238         ac = talloc(req, struct kludge_acl_context);
 239         if (ac == NULL) {
 240                 return LDB_ERR_OPERATIONS_ERROR;
 241         }
 242
 243         data = talloc_get_type(module->private_data, struct kludge_private_data);
 244
 245         ac->module = module;
 246         ac->up_context = req->context;
 247         ac->up_callback = req->callback;
 248         ac->user_type = what_is_user(module);
 249         ac->attrs = req->op.search.attrs;
 250
 251         down_req = talloc_zero(req, struct ldb_request);
 252         if (down_req == NULL) {
 253                 return LDB_ERR_OPERATIONS_ERROR;
 254         }
 255
 256         down_req->operation = req->operation;
 257         down_req->op.search.base = req->op.search.base;
 258         down_req->op.search.scope = req->op.search.scope;
 259         down_req->op.search.tree = req->op.search.tree;
 260         down_req->op.search.attrs = req->op.search.attrs;
 261
 262         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 263
 264         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 265
 266         if (ac->allowedAttributes || ac->allowedAttributesEffective) {
 267                 down_req->op.search.attrs
 268                         = ldb_attr_list_copy_add(down_req, down_req->op.search.attrs, "objectClass");
 269         }
 270
 271         /*  FIXME: I hink we should copy the tree and keep the original
 272          *  unmodified. SSS */
 273         /* replace any attributes in the parse tree that are private,
 274            so we don't allow a search for 'sambaPassword=penguin',
 275            just as we would not allow that attribute to be returned */
 276         switch (ac->user_type) {
 277         case SYSTEM:
 278                 break;
 279         default:
 280                 /* remove password attributes */
 281                 for (i = 0; data && data->password_attrs && data->password_attrs[i]; i++) {
 282                         ldb_parse_tree_attr_replace(down_req->op.search.tree,
 283                                                     data->password_attrs[i],
 284                                                     "kludgeACLredactedattribute");
 285                 }
 286         }
 287
 288         down_req->controls = req->controls;
 289
 290         down_req->context = ac;
 291         down_req->callback = kludge_acl_callback;
 292         ldb_set_timeout_from_prev_req(module->ldb, req, down_req);
 293
 294         /* perform the search */
 295         ret = ldb_next_request(module, down_req);
 296
 297         /* do not free down_req as the call results may be linked to it,
 298          * it will be freed when the upper level request get freed */
 299         if (ret == LDB_SUCCESS) {
 300                 req->handle = down_req->handle;
 301         }
 302
 303         return ret;
 304 }
 305
 306 /* ANY change type */
 307 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 308 {
 309         enum user_is user_type = what_is_user(module);
 310         switch (user_type) {
 311         case SYSTEM:
 312         case ADMINISTRATOR:
 313                 return ldb_next_request(module, req);
 314         default:
 315                 ldb_asprintf_errstring(module->ldb,
 316                                        "kludge_acl_change: "
 317                                        "attempted database modify not permitted. "
 318                                        "User %s is not SYSTEM or an administrator",
 319                                        user_name(req, module));
 320                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 321         }
 322 }
 323
 324 static int kludge_acl_init(struct ldb_module *module)
 325 {
 326         int ret, i;
 327         TALLOC_CTX *mem_ctx = talloc_new(module);
 328         static const char *attrs[] = { "passwordAttribute", NULL };
 329         struct ldb_result *res;
 330         struct ldb_message *msg;
 331         struct ldb_message_element *password_attributes;
 332
 333         struct kludge_private_data *data;
 334
 335         data = talloc(module, struct kludge_private_data);
 336         if (data == NULL) {
 337                 return LDB_ERR_OPERATIONS_ERROR;
 338         }
 339
 340         data->password_attrs = NULL;
 341         module->private_data = data;
 342
 343         if (!mem_ctx) {
 344                 return LDB_ERR_OPERATIONS_ERROR;
 345         }
 346
 347         ret = ldb_search(module->ldb, ldb_dn_new(mem_ctx, module->ldb, "@KLUDGEACL"),
 348                          LDB_SCOPE_BASE,
 349                          NULL, attrs,
 350                          &res);
 351         if (ret != LDB_SUCCESS) {
 352                 goto done;
 353         }
 354         talloc_steal(mem_ctx, res);
 355         if (res->count == 0) {
 356                 goto done;
 357         }
 358
 359         if (res->count > 1) {
 360                 talloc_free(mem_ctx);
 361                 return LDB_ERR_CONSTRAINT_VIOLATION;
 362         }
 363
 364         msg = res->msgs[0];
 365
 366         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 367         if (!password_attributes) {
 368                 goto done;
 369         }
 370         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 371         if (!data->password_attrs) {
 372                 talloc_free(mem_ctx);
 373                 return LDB_ERR_OPERATIONS_ERROR;
 374         }
 375         for (i=0; i < password_attributes->num_values; i++) {
 376                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 377                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 378         }
 379         data->password_attrs[i] = NULL;
 380
 381 done:
 382         talloc_free(mem_ctx);
 383         return ldb_next_init(module);
 384 }
 385
 386 static const struct ldb_module_ops kludge_acl_ops = {
 387         .name              = "kludge_acl",
 388         .search            = kludge_acl_search,
 389         .add               = kludge_acl_change,
 390         .modify            = kludge_acl_change,
 391         .del               = kludge_acl_change,
 392         .rename            = kludge_acl_change,
 393         .extended          = kludge_acl_change,
 394         .init_context      = kludge_acl_init
 395 };
 396
 397 int ldb_kludge_acl_init(void)
 398 {
 399         return ldb_register_module(&kludge_acl_ops);
 400 }