# User-Defined Functions Security

The MariaDB server imposes a number of limitations on [user-defined functions](https://mariadb.com/docs/server/server-usage/user-defined-functions) for security purposes.

* The `INSERT` privilege for the mysql database is required to run [CREATE FUNCTION](https://mariadb.com/docs/server/server-usage/user-defined-functions/create-function-udf), as a record are added to the [mysql.func-table](https://mariadb.com/docs/server/reference/system-tables/the-mysql-database-tables/mysql-func-table).
* The `DELETE` privilege for the mysql database is required to run [DROP FUNCTION](https://mariadb.com/docs/server/server-usage/user-defined-functions/drop-function-udf) as the corresponding record are removed from the [mysql.func-table](https://mariadb.com/docs/server/reference/system-tables/the-mysql-database-tables/mysql-func-table).
* UDF object files can only be placed in the plugin directory, as specified by the value of the [plugin\_dir](https://mariadb.com/docs/server/server-management/variables-and-modes/server-system-variables#plugin_dir) system variable.
* At least one symbol, beyond the required `x()` , corresponding to an SQL function `X()`, is required. These can be `x_init()`, `x_deinit()`, `xxx_reset()`, `x_clear()`, and `x_add()` functions (see [Creating User-defined Functions](https://mariadb.com/docs/server/server-usage/user-defined-functions/creating-user-defined-functions)). The [allow-suspicious-udfs](https://mariadb.com/docs/server/server-management/starting-and-stopping-mariadb/mariadbd-options#-allow-suspicious-udfs) mariadbd option (by default unset) provides a workaround, permitting only one symbol to be used. This is not recommended, as it opens the possibility of loading shared objects that are not legitimate user-defined functions.

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