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 2 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, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /*
  23  *  Name: ldb
  24  *
  25  *  Component: ldb kludge ACL module
  26  *
  27  *  Description: Simple module to enforce a simple form of access
  28  *               control, sufficient for securing a default Samba4
  29  *               installation.
  30  *
  31  *  Author: Andrew Bartlett
  32  */
  33
  34 #include "includes.h"
  35 #include "ldb/include/ldb.h"
  36 #include "ldb/include/ldb_errors.h"
  37 #include "ldb/include/ldb_private.h"
  38 #include "auth/auth.h"
  39 #include "libcli/security/security.h"
  40 #include "dsdb/samdb/samdb.h"
  41
  42 /* Kludge ACL rules:
  43  *
  44  * - System can read passwords
  45  * - Administrators can write anything
  46  * - Users can read anything that is not a password
  47  *
  48  */
  49
  50 enum user_is {
  51         ANONYMOUS,
  52         USER,
  53         ADMINISTRATOR,
  54         SYSTEM
  55 };
  56
  57 struct kludge_private_data {
  58         const char **password_attrs;
  59 };
  60
  61 static enum user_is what_is_user(struct ldb_module *module)
  62 {
  63         struct auth_session_info *session_info
  64                 = ldb_get_opaque(module->ldb, "sessionInfo");
  65         if (!session_info) {
  66                 return ANONYMOUS;
  67         }
  68
  69         if (security_token_is_system(session_info->security_token)) {
  70                 return SYSTEM;
  71         }
  72
  73         if (security_token_is_anonymous(session_info->security_token)) {
  74                 return ANONYMOUS;
  75         }
  76
  77         if (security_token_has_builtin_administrators(session_info->security_token)) {
  78                 return ADMINISTRATOR;
  79         }
  80
  81         if (security_token_has_nt_authenticated_users(session_info->security_token)) {
  82                 return USER;
  83         }
  84
  85         return ANONYMOUS;
  86 }
  87
  88 static const char *user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
  89 {
  90         struct auth_session_info *session_info
  91                 = ldb_get_opaque(module->ldb, "sessionInfo");
  92         if (!session_info) {
  93                 return "UNKNOWN (NULL)";
  94         }
  95
  96         return talloc_asprintf(mem_ctx, "%s\\%s",
  97                                session_info->server_info->domain_name,
  98                                session_info->server_info->account_name);
  99 }
 100
 101 /* search */
 102 struct kludge_acl_context {
 103
 104         struct ldb_module *module;
 105         void *up_context;
 106         int (*up_callback)(struct ldb_context *, void *, struct ldb_reply *);
 107
 108         enum user_is user_type;
 109         bool allowedAttributes;
 110         bool allowedAttributesEffective;
 111         const char **attrs;
 112 };
 113
 114 /* read all objectClasses */
 115
 116 static int kludge_acl_allowedAttributes(struct ldb_context *ldb, struct ldb_message *msg,
 117                                                          const char *attrName)
 118 {
 119         struct ldb_message_element *oc_el = ldb_msg_find_element(msg, "objectClass");
 120         struct ldb_message_element *allowedAttributes;
 121         const struct dsdb_schema *schema = dsdb_get_schema(ldb);
 122         const struct dsdb_class *class;
 123         int i, j, ret;
 124         ret = ldb_msg_add_empty(msg, attrName, 0, &allowedAttributes);
 125         if (ret != LDB_SUCCESS) {
 126                 return ret;
 127         }
 128
 129         for (i=0; i < oc_el->num_values; i++) {
 130                 class = dsdb_class_by_lDAPDisplayName(schema, (const char *)oc_el->values[i].data);
 131                 if (!class) {
 132                         /* We don't know this class?  what is going on? */
 133                         continue;
 134                 }
 135                 for (j=0; class->mayContain && class->mayContain[j]; j++) {
 136                         ldb_msg_add_string(msg, attrName, class->mayContain[j]);
 137                 }
 138                 for (j=0; class->mustContain && class->mustContain[j]; j++) {
 139                         ldb_msg_add_string(msg, attrName, class->mustContain[j]);
 140                 }
 141                 for (j=0; class->systemMayContain && class->systemMayContain[j]; j++) {
 142                         ldb_msg_add_string(msg, attrName, class->systemMayContain[j]);
 143                 }
 144                 for (j=0; class->systemMustContain && class->systemMustContain[j]; j++) {
 145                         ldb_msg_add_string(msg, attrName, class->systemMustContain[j]);
 146                 }
 147         }
 148
 149         if (allowedAttributes->num_values > 1) {
 150                 qsort(allowedAttributes->values,
 151                       allowedAttributes->num_values,
 152                       sizeof(*allowedAttributes->values),
 153                       data_blob_cmp);
 154
 155                 for (i=1 ; i < allowedAttributes->num_values; i++) {
 156                         struct ldb_val *val1 = &allowedAttributes->values[i-1];
 157                         struct ldb_val *val2 = &allowedAttributes->values[i];
 158                         if (data_blob_cmp(val1, val2) == 0) {
 159                                 memmove(val1, val2, (allowedAttributes->num_values - i) * sizeof( struct ldb_val));
 160                                 allowedAttributes->num_values--;
 161                                 i--;
 162                         }
 163                 }
 164         }
 165
 166         return 0;
 167
 168 }
 169
 170 /* find all attributes allowed by all these objectClasses */
 171
 172 static int kludge_acl_callback(struct ldb_context *ldb, void *context, struct ldb_reply *ares)
 173 {
 174         struct kludge_acl_context *ac;
 175         struct kludge_private_data *data;
 176         int i, ret;
 177
 178         if (!context || !ares) {
 179                 ldb_set_errstring(ldb, "NULL Context or Result in callback");
 180                 goto error;
 181         }
 182
 183         ac = talloc_get_type(context, struct kludge_acl_context);
 184         data = talloc_get_type(ac->module->private_data, struct kludge_private_data);
 185
 186         if (ares->type != LDB_REPLY_ENTRY) {
 187                 return ac->up_callback(ldb, ac->up_context, ares);
 188         }
 189
 190         if (ac->allowedAttributes) {
 191                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributes");
 192                 if (ret != LDB_SUCCESS) {
 193                         return ret;
 194                 }
 195         }
 196
 197         if (data && data->password_attrs) /* if we are not initialized just get through */
 198         {
 199                 switch (ac->user_type) {
 200                 case SYSTEM:
 201                 case ADMINISTRATOR:
 202                         if (ac->allowedAttributesEffective) {
 203                                 ret = kludge_acl_allowedAttributes(ldb, ares->message, "allowedAttributesEffective");
 204                                 if (ret != LDB_SUCCESS) {
 205                                         return ret;
 206                                 }
 207                         }
 208                         break;
 209                 default:
 210                         /* remove password attributes */
 211                         for (i = 0; data->password_attrs[i]; i++) {
 212                                 ldb_msg_remove_attr(ares->message, data->password_attrs[i]);
 213                         }
 214                 }
 215         }
 216
 217         if ((ac->allowedAttributes || ac->allowedAttributesEffective) &&
 218             (!ldb_attr_in_list(ac->attrs, "objectClass") &&
 219              !ldb_attr_in_list(ac->attrs, "*"))) {
 220                 ldb_msg_remove_attr(ares->message, "objectClass");
 221         }
 222
 223         return ac->up_callback(ldb, ac->up_context, ares);
 224
 225 error:
 226         talloc_free(ares);
 227         return LDB_ERR_OPERATIONS_ERROR;
 228 }
 229
 230 static int kludge_acl_search(struct ldb_module *module, struct ldb_request *req)
 231 {
 232         struct kludge_acl_context *ac;
 233         struct ldb_request *down_req;
 234         struct kludge_private_data *data;
 235         int ret, i;
 236
 237         req->handle = NULL;
 238
 239         ac = talloc(req, struct kludge_acl_context);
 240         if (ac == NULL) {
 241                 return LDB_ERR_OPERATIONS_ERROR;
 242         }
 243
 244         data = talloc_get_type(module->private_data, struct kludge_private_data);
 245
 246         ac->module = module;
 247         ac->up_context = req->context;
 248         ac->up_callback = req->callback;
 249         ac->user_type = what_is_user(module);
 250         ac->attrs = req->op.search.attrs;
 251
 252         down_req = talloc_zero(req, struct ldb_request);
 253         if (down_req == NULL) {
 254                 return LDB_ERR_OPERATIONS_ERROR;
 255         }
 256
 257         down_req->operation = req->operation;
 258         down_req->op.search.base = req->op.search.base;
 259         down_req->op.search.scope = req->op.search.scope;
 260         down_req->op.search.tree = req->op.search.tree;
 261         down_req->op.search.attrs = req->op.search.attrs;
 262
 263         ac->allowedAttributes = ldb_attr_in_list(req->op.search.attrs, "allowedAttributes");
 264
 265         ac->allowedAttributesEffective = ldb_attr_in_list(req->op.search.attrs, "allowedAttributesEffective");
 266
 267         if (ac->allowedAttributes || ac->allowedAttributesEffective) {
 268                 down_req->op.search.attrs
 269                         = ldb_attr_list_copy_add(down_req, down_req->op.search.attrs, "objectClass");
 270         }
 271
 272         /*  FIXME: I hink we should copy the tree and keep the original
 273          *  unmodified. SSS */
 274         /* replace any attributes in the parse tree that are private,
 275            so we don't allow a search for 'sambaPassword=penguin',
 276            just as we would not allow that attribute to be returned */
 277         switch (ac->user_type) {
 278         case SYSTEM:
 279                 break;
 280         default:
 281                 /* remove password attributes */
 282                 for (i = 0; data && data->password_attrs && data->password_attrs[i]; i++) {
 283                         ldb_parse_tree_attr_replace(down_req->op.search.tree,
 284                                                     data->password_attrs[i],
 285                                                     "kludgeACLredactedattribute");
 286                 }
 287         }
 288
 289         down_req->controls = req->controls;
 290
 291         down_req->context = ac;
 292         down_req->callback = kludge_acl_callback;
 293         ldb_set_timeout_from_prev_req(module->ldb, req, down_req);
 294
 295         /* perform the search */
 296         ret = ldb_next_request(module, down_req);
 297
 298         /* do not free down_req as the call results may be linked to it,
 299          * it will be freed when the upper level request get freed */
 300         if (ret == LDB_SUCCESS) {
 301                 req->handle = down_req->handle;
 302         }
 303
 304         return ret;
 305 }
 306
 307 /* ANY change type */
 308 static int kludge_acl_change(struct ldb_module *module, struct ldb_request *req)
 309 {
 310         enum user_is user_type = what_is_user(module);
 311         switch (user_type) {
 312         case SYSTEM:
 313         case ADMINISTRATOR:
 314                 return ldb_next_request(module, req);
 315         default:
 316                 ldb_asprintf_errstring(module->ldb,
 317                                        "kludge_acl_change: "
 318                                        "attempted database modify not permitted. "
 319                                        "User %s is not SYSTEM or an administrator",
 320                                        user_name(req, module));
 321                 return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
 322         }
 323 }
 324
 325 static int kludge_acl_init(struct ldb_module *module)
 326 {
 327         int ret, i;
 328         TALLOC_CTX *mem_ctx = talloc_new(module);
 329         static const char *attrs[] = { "passwordAttribute", NULL };
 330         struct ldb_result *res;
 331         struct ldb_message *msg;
 332         struct ldb_message_element *password_attributes;
 333
 334         struct kludge_private_data *data;
 335
 336         data = talloc(module, struct kludge_private_data);
 337         if (data == NULL) {
 338                 return LDB_ERR_OPERATIONS_ERROR;
 339         }
 340
 341         data->password_attrs = NULL;
 342         module->private_data = data;
 343
 344         if (!mem_ctx) {
 345                 return LDB_ERR_OPERATIONS_ERROR;
 346         }
 347
 348         ret = ldb_search(module->ldb, ldb_dn_new(mem_ctx, module->ldb, "@KLUDGEACL"),
 349                          LDB_SCOPE_BASE,
 350                          NULL, attrs,
 351                          &res);
 352         if (ret != LDB_SUCCESS) {
 353                 goto done;
 354         }
 355         talloc_steal(mem_ctx, res);
 356         if (res->count == 0) {
 357                 goto done;
 358         }
 359
 360         if (res->count > 1) {
 361                 talloc_free(mem_ctx);
 362                 return LDB_ERR_CONSTRAINT_VIOLATION;
 363         }
 364
 365         msg = res->msgs[0];
 366
 367         password_attributes = ldb_msg_find_element(msg, "passwordAttribute");
 368         if (!password_attributes) {
 369                 goto done;
 370         }
 371         data->password_attrs = talloc_array(data, const char *, password_attributes->num_values + 1);
 372         if (!data->password_attrs) {
 373                 talloc_free(mem_ctx);
 374                 return LDB_ERR_OPERATIONS_ERROR;
 375         }
 376         for (i=0; i < password_attributes->num_values; i++) {
 377                 data->password_attrs[i] = (const char *)password_attributes->values[i].data;
 378                 talloc_steal(data->password_attrs, password_attributes->values[i].data);
 379         }
 380         data->password_attrs[i] = NULL;
 381
 382 done:
 383         talloc_free(mem_ctx);
 384         return ldb_next_init(module);
 385 }
 386
 387 static const struct ldb_module_ops kludge_acl_ops = {
 388         .name              = "kludge_acl",
 389         .search            = kludge_acl_search,
 390         .add               = kludge_acl_change,
 391         .modify            = kludge_acl_change,
 392         .del               = kludge_acl_change,
 393         .rename            = kludge_acl_change,
 394         .extended          = kludge_acl_change,
 395         .init_context      = kludge_acl_init
 396 };
 397
 398 int ldb_kludge_acl_init(void)
 399 {
 400         return ldb_register_module(&kludge_acl_ops);
 401 }