4.12 Server Handling of Expired Passwords

MySQL provides password-expiration capability, which enables database administrators to require that users reset their password. Passwords can be expired manually, and on the basis of a policy for automatic expiration (see Section 4.11, “Password Management”).

The ALTER USER statement enables account password expiration. For example:

ALTER USER 'myuser'@'localhost' PASSWORD EXPIRE;

For each connection that uses an account with an expired password, the server either disconnects the client or restricts the client to “sandbox mode,” in which the server permits the client to perform only those operations necessary to reset the expired password. Which action is taken by the server depends on both client and server settings, as discussed later.

If the server disconnects the client, it returns an ER_MUST_CHANGE_PASSWORD_LOGIN error:

$> mysql -u myuser -p
Password: ******
ERROR 1862 (HY000): Your password has expired. To log in you must
change it using a client that supports expired passwords.

If the server restricts the client to sandbox mode, these operations are permitted within the client session:

• The client can reset the account password with ALTER USER or SET PASSWORD. After that has been done, the server restores normal access for the session, as well as for subsequent connections that use the account.

  Note

  Although it is possible to “reset” an expired password by setting it to its current value, it is preferable, as a matter of good policy, to choose a different password.

• The client can use the SET statement, which is useful before MySQL 5.7.6 if SET PASSWORD must be used instead of ALTER USER and the account uses an authentication plugin for which the old_passwords system variable must first be set to a nondefault value to perform password hashing in a specific way.

For any operation not permitted within the session, the server returns an ER_MUST_CHANGE_PASSWORD error:

mysql> USE performance_schema;
ERROR 1820 (HY000): You must reset your password using ALTER USER
statement before executing this statement.
mysql> SELECT 1;
ERROR 1820 (HY000): You must reset your password using ALTER USER
statement before executing this statement.

That is what normally happens for interactive invocations of the mysql client because by default such invocations are put in sandbox mode. To resume normal functioning, select a new password.

For noninteractive invocations of the mysql client (for example, in batch mode), the server normally disconnects the client if the password is expired. To permit noninteractive mysql invocations to stay connected so that the password can be changed (using the statements permitted in sandbox mode), add the --connect-expired-password option to the mysql command.

As mentioned previously, whether the server disconnects an expired-password client or restricts it to sandbox mode depends on a combination of client and server settings. The following discussion describes the relevant settings and how they interact.

Note

This discussion applies only for accounts with expired passwords. If a client connects using a nonexpired password, the server handles the client normally.

On the client side, a given client indicates whether it can handle sandbox mode for expired passwords. For clients that use the C client library, there are two ways to do this:

• Pass the MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS flag to mysql_options() prior to connecting:

  my_bool arg = 1;
  mysql_options(mysql,
                MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS,
                &arg);

  This is the technique used within the mysql client, which enables MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS if invoked interactively or with the --connect-expired-password option.

• Pass the CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS flag to mysql_real_connect() at connect time:

  MYSQL mysql;
  mysql_init(&mysql);
  if (!mysql_real_connect(&mysql,
                          host, user, password, db,
                          port, unix_socket,
                          CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS))
  {
    ... handle error ...
  }

Other MySQL Connectors have their own conventions for indicating readiness to handle sandbox mode. See the documentation for the Connector in which you are interested.

On the server side, if a client indicates that it can handle expired passwords, the server puts it in sandbox mode.

If a client does not indicate that it can handle expired passwords (or uses an older version of the client library that cannot so indicate), the server action depends on the value of the disconnect_on_expired_password system variable:

• If disconnect_on_expired_password is enabled (the default), the server disconnects the client with an ER_MUST_CHANGE_PASSWORD_LOGIN error.

• If disconnect_on_expired_password is disabled, the server puts the client in sandbox mode.