The mysql_no_login
server-side authentication
plugin prevents all client connections to any account that uses
it. Use cases for this plugin include:
Accounts that must be able to execute stored programs and views with elevated privileges without exposing those privileges to ordinary users.
Proxied accounts that should never permit direct login but are intended to be accessed only through proxy accounts.
The following table shows the plugin and library file names. The
file name suffix might differ on your system. The file must be
located in the directory named by the
plugin_dir
system variable.
Table 8.24 Plugin and Library Names for No-Login Authentication
Plugin or File | Plugin or File Name |
---|---|
Server-side plugin | mysql_no_login |
Client-side plugin | None |
Library file | mysql_no_login.so |
The following sections provide installation and usage information specific to no-login pluggable authentication:
For general information about pluggable authentication in MySQL, see Section 8.2.17, “Pluggable Authentication”. For proxy user information, see Section 8.2.19, “Proxy Users”.
This section describes how to install the no-login authentication plugin. For general information about installing plugins, see Section 7.6.1, “Installing and Uninstalling Plugins”.
To be usable by the server, the plugin library file must be
located in the MySQL plugin directory (the directory named by
the plugin_dir
system
variable). If necessary, configure the plugin directory
location by setting the value of
plugin_dir
at server startup.
The plugin library file base name is
mysql_no_login
. The file name suffix
differs per platform (for example, .so
for Unix and Unix-like systems, .dll
for
Windows).
To load the plugin at server startup, use the
--plugin-load-add
option to
name the library file that contains it. With this
plugin-loading method, the option must be given each time the
server starts. For example, put these lines in the server
my.cnf
file, adjusting the
.so
suffix for your platform as
necessary:
[mysqld]
plugin-load-add=mysql_no_login.so
After modifying my.cnf
, restart the
server to cause the new settings to take effect.
Alternatively, to load the plugin at runtime, use this
statement, adjusting the .so
suffix for
your platform as necessary:
INSTALL PLUGIN mysql_no_login SONAME 'mysql_no_login.so';
INSTALL PLUGIN
loads the plugin
immediately, and also registers it in the
mysql.plugins
system table to cause the
server to load it for each subsequent normal startup without
the need for --plugin-load-add
.
To verify plugin installation, examine the Information Schema
PLUGINS
table or use the
SHOW PLUGINS
statement (see
Section 7.6.2, “Obtaining Server Plugin Information”). For example:
mysql> SELECT PLUGIN_NAME, PLUGIN_STATUS
FROM INFORMATION_SCHEMA.PLUGINS
WHERE PLUGIN_NAME LIKE '%login%';
+----------------+---------------+
| PLUGIN_NAME | PLUGIN_STATUS |
+----------------+---------------+
| mysql_no_login | ACTIVE |
+----------------+---------------+
If the plugin fails to initialize, check the server error log for diagnostic messages.
To associate MySQL accounts with the no-login plugin, see Using No-Login Pluggable Authentication.
The method used to uninstall the no-login authentication plugin depends on how you installed it:
If you installed the plugin at server startup using a
--plugin-load-add
option, restart the server without the option.If you installed the plugin at runtime using an
INSTALL PLUGIN
statement, it remains installed across server restarts. To uninstall it, useUNINSTALL PLUGIN
:UNINSTALL PLUGIN mysql_no_login;
This section describes how to use the no-login authentication plugin to prevent accounts from being used for connecting from MySQL client programs to the server. It is assumed that the server is running with the no-login plugin enabled, as described in Installing No-Login Pluggable Authentication.
To refer to the no-login authentication plugin in the
IDENTIFIED WITH
clause of a
CREATE USER
statement, use the
name mysql_no_login
.
An account that authenticates using
mysql_no_login
may be used as the
DEFINER
for stored program and view
objects. If such an object definition also includes
SQL SECURITY DEFINER
, it executes with that
account's privileges. DBAs can use this behavior to provide
access to confidential or sensitive data that is exposed only
through well-controlled interfaces.
The following example illustrates these principles. It defines
an account that does not permit client connections, and
associates with it a view that exposes only certain columns of
the mysql.user
system table:
CREATE DATABASE nologindb;
CREATE USER 'nologin'@'localhost'
IDENTIFIED WITH mysql_no_login;
GRANT ALL ON nologindb.*
TO 'nologin'@'localhost';
GRANT SELECT ON mysql.user
TO 'nologin'@'localhost';
CREATE DEFINER = 'nologin'@'localhost'
SQL SECURITY DEFINER
VIEW nologindb.myview
AS SELECT User, Host FROM mysql.user;
To provide protected access to the view to an ordinary user, do this:
GRANT SELECT ON nologindb.myview
TO 'ordinaryuser'@'localhost';
Now the ordinary user can use the view to access the limited information it presents:
SELECT * FROM nologindb.myview;
Attempts by the user to access columns other than those exposed by the view result in an error, as do attempts to select from the view by users not granted access to it.
Because the nologin
account cannot be
used directly, the operations required to set up objects
that it uses must be performed by root
or
similar account that has the privileges required to create
the objects and set DEFINER
values.
The mysql_no_login
plugin is also useful in
proxying scenarios. (For a discussion of concepts involved in
proxying, see Section 8.2.19, “Proxy Users”.) An account that
authenticates using mysql_no_login
may be
used as a proxied user for proxy accounts:
-- create proxied account
CREATE USER 'proxied_user'@'localhost'
IDENTIFIED WITH mysql_no_login;
-- grant privileges to proxied account
GRANT ...
ON ...
TO 'proxied_user'@'localhost';
-- permit proxy_user to be a proxy account for proxied account
GRANT PROXY
ON 'proxied_user'@'localhost'
TO 'proxy_user'@'localhost';
This enables clients to access MySQL through the proxy account
(proxy_user
) but not to bypass the proxy
mechanism by connecting directly as the proxied user
(proxied_user
). A client who connects using
the proxy_user
account has the privileges
of the proxied_user
account, but
proxied_user
itself cannot be used to
connect.
For alternative methods of protecting proxied accounts against direct use, see Preventing Direct Login to Proxied Accounts.