/*
  ACL utility functions

  Copyright (C) Nadezhda Ivanova 2010

  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
 *  Name: acl_util
 *
 *  Component: ldb ACL modules
 *
 *  Description: Some auxiliary functions used for access checking
 *
 *  Author: Nadezhda Ivanova
 */
#include "includes.h"
#include "ldb_module.h"
#include "auth/auth.h"
#include "libcli/security/security.h"
#include "dsdb/samdb/samdb.h"
#include "librpc/gen_ndr/ndr_security.h"
#include "param/param.h"
#include "dsdb/samdb/ldb_modules/util.h"

struct security_token *acl_user_token(struct ldb_module *module)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
	if(!session_info) {
		return NULL;
	}
	return session_info->security_token;
}

/* performs an access check from inside the module stack
 * given the dn of the object to be checked, the required access
 * guid is either the guid of the extended right, or NULL
 */

int dsdb_module_check_access_on_dn(struct ldb_module *module,
				   TALLOC_CTX *mem_ctx,
				   struct ldb_dn *dn,
				   uint32_t access,
				   const struct GUID *guid)
{
	int ret;
	struct ldb_result *acl_res;
	static const char *acl_attrs[] = {
		"nTSecurityDescriptor",
		"objectSid",
		NULL
	};
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
	if(!session_info) {
		return ldb_operr(ldb);
	}
	ret = dsdb_module_search_dn(module, mem_ctx, &acl_res, dn,
				    acl_attrs,
				    DSDB_FLAG_NEXT_MODULE |
				    DSDB_SEARCH_SHOW_DELETED);
	if (ret != LDB_SUCCESS) {
		DEBUG(0,("access_check: failed to find object %s\n", ldb_dn_get_linearized(dn)));
		return ret;
	}
	return dsdb_check_access_on_dn_internal(ldb, acl_res,
						mem_ctx,
						session_info->security_token,
						dn,
						access,
						guid);
}

int acl_check_access_on_attribute(struct ldb_module *module,
				  TALLOC_CTX *mem_ctx,
				  struct security_descriptor *sd,
				  struct dom_sid *rp_sid,
				  uint32_t access,
				  const struct dsdb_attribute *attr)
{
	int ret;
	NTSTATUS status;
	uint32_t access_granted;
	struct object_tree *root = NULL;
	struct object_tree *new_node = NULL;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	struct security_token *token = acl_user_token(module);
	if (attr) {
		if (!GUID_all_zero(&attr->attributeSecurityGUID)) {
			if (!insert_in_object_tree(tmp_ctx,
						   &attr->attributeSecurityGUID, access,
						   &root, &new_node)) {
				DEBUG(10, ("acl_search: cannot add to object tree securityGUID\n"));
				goto fail;
			}

			if (!insert_in_object_tree(tmp_ctx,
						   &attr->schemaIDGUID, access, &new_node, &new_node)) {
				DEBUG(10, ("acl_search: cannot add to object tree attributeGUID\n"));
				goto fail;
			}
		}
		else {
			if (!insert_in_object_tree(tmp_ctx,
						   &attr->schemaIDGUID, access, &root, &new_node)) {
				DEBUG(10, ("acl_search: cannot add to object tree attributeGUID\n"));
				goto fail;
			}
		}
	}
	status = sec_access_check_ds(sd, token,
				     access,
				     &access_granted,
				     root,
				     rp_sid);
	if (!NT_STATUS_IS_OK(status)) {
		ret = LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}
	else {
		ret = LDB_SUCCESS;
	}
	talloc_free(tmp_ctx);
	return ret;
fail:
	talloc_free(tmp_ctx);
	return ldb_operr(ldb_module_get_ctx(module));
}

int acl_check_access_on_class(struct ldb_module *module,
			      const struct dsdb_schema *schema,
			      TALLOC_CTX *mem_ctx,
			      struct security_descriptor *sd,
			      struct dom_sid *rp_sid,
			      uint32_t access,
			      const char *class_name)
{
	int ret;
	NTSTATUS status;
	uint32_t access_granted;
	struct object_tree *root = NULL;
	struct object_tree *new_node = NULL;
	const struct GUID *guid;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
	struct security_token *token = acl_user_token(module);
	if (class_name) {
		guid = class_schemaid_guid_by_lDAPDisplayName(schema, class_name);
		if (!guid) {
			DEBUG(10, ("acl_search: cannot find class %s\n",
				   class_name));
			goto fail;
		}
		if (!insert_in_object_tree(tmp_ctx,
					   guid, access,
					   &root, &new_node)) {
			DEBUG(10, ("acl_search: cannot add to object tree guid\n"));
			goto fail;
		}
	}
	status = sec_access_check_ds(sd, token,
				     access,
				     &access_granted,
				     root,
				     rp_sid);
	if (!NT_STATUS_IS_OK(status)) {
		ret = LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}
	else {
		ret = LDB_SUCCESS;
	}
	return ret;
fail:
	return ldb_operr(ldb_module_get_ctx(module));
}

const struct GUID *get_oc_guid_from_message(struct ldb_module *module,
						   const struct dsdb_schema *schema,
						   struct ldb_message *msg)
{
	struct ldb_message_element *oc_el;

	oc_el = ldb_msg_find_element(msg, "objectClass");
	if (!oc_el) {
		return NULL;
	}

	return class_schemaid_guid_by_lDAPDisplayName(schema,
						      (char *)oc_el->values[oc_el->num_values-1].data);
}


/* checks for validated writes */
int acl_check_extended_right(TALLOC_CTX *mem_ctx,
			     struct security_descriptor *sd,
			     struct security_token *token,
			     const char *ext_right,
			     uint32_t right_type,
			     struct dom_sid *sid)
{
	struct GUID right;
	NTSTATUS status;
	uint32_t access_granted;
	struct object_tree *root = NULL;
	struct object_tree *new_node = NULL;
	TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);

	GUID_from_string(ext_right, &right);

	if (!insert_in_object_tree(tmp_ctx, &right, right_type,
				   &root, &new_node)) {
		DEBUG(10, ("acl_ext_right: cannot add to object tree\n"));
		talloc_free(tmp_ctx);
		return LDB_ERR_OPERATIONS_ERROR;
	}
	status = sec_access_check_ds(sd, token,
				     right_type,
				     &access_granted,
				     root,
				     sid);

	if (!NT_STATUS_IS_OK(status)) {
		talloc_free(tmp_ctx);
		return LDB_ERR_INSUFFICIENT_ACCESS_RIGHTS;
	}
	talloc_free(tmp_ctx);
	return LDB_SUCCESS;
}

const char *acl_user_name(TALLOC_CTX *mem_ctx, struct ldb_module *module)
{
	struct ldb_context *ldb = ldb_module_get_ctx(module);
	struct auth_session_info *session_info
		= (struct auth_session_info *)ldb_get_opaque(ldb, "sessionInfo");
	if (!session_info) {
		return "UNKNOWN (NULL)";
	}

	return talloc_asprintf(mem_ctx, "%s\\%s",
			       session_info->server_info->domain_name,
			       session_info->server_info->account_name);
}