FirebirdSQL logo
  • Anglaiskeyboard_arrow_down
 Statements for Revoking PrivilegesDatabase Encryption 

Now Firebird support multiple security databases, new problems arise that could not occur with a single, global security database.Clusters of databases using the same security database are effectively separated.Mappings provide the means to achieve the same effect when multiple databases are using their own security databases.Some cases require control for limited interaction between such clusters.For example:

  • when EXECUTE STATEMENT ON EXTERNAL DATA SOURCE requires data exchange between clusters

  • when server-wide SYSDBA access to databases is needed from other clusters, using services.

  • On Windows, due to support for Trusted User authentication: to map Windows users to a Firebird user and/or role.An example is the need for a ROLE granted to a Windows group to be assigned automatically to members of that group.

The single solution for all such cases is mapping the login information assigned to a user when it connects to a Firebird server to internal security objects in a database — CURRENT_USER and CURRENT_ROLE.

The Mapping Rule

The mapping rule consists of four pieces of information:

  1. mapping scope — whether the mapping is local to the current database or whether its effect is to be global, affecting all databases in the cluster, including security databases

  2. mapping name — an SQL identifier, since mappings are objects in a database, like any other

  3. the object FROM which the mapping maps.It consists of four items:

    • The authentication source

      • plugin name or

      • the product of a mapping in another database or

      • use of server-wide authentication or

      • any method

    • The name of the database where authentication succeeded

    • The name of the object from which mapping is performed

    • The type of that name — username, role, or OS group — depending upon the plugin that added that name during authentication.

      Any item is accepted but only type is required.

  4. the object TO which the mapping maps.It consists of two items:

    • The name of the object TO which mapping is performed

    • The type, for which only USER or ROLE is valid

CREATE MAPPING

Creates a mapping of a security object

Available in

DSQL

Syntax
CREATE [GLOBAL] MAPPING name
  USING
    { PLUGIN plugin_name [IN database]
    | ANY PLUGIN [IN database | SERVERWIDE]
    | MAPPING [IN database] | '*' [IN database] }
  FROM {ANY type | type from_name}
  TO {USER | ROLE} [to_name]
Table 1. CREATE MAPPING Statement Parameter
Parameter Description

name

Mapping nameThe maximum length is 63 characters.Must be unique among all mapping names in the context (local or GLOBAL).

plugin_name

Authentication plugin name

database

Name of the database that authenticated against

type

The type of object to be mapped.Possible types are plugin-specific.

from_name

The name of the object to be mapped

to_name

The name of the user or role to map to

The CREATE MAPPING statement creates a mapping of security objects (e.g. users, groups, roles) of one or more authentication plugins to internal security objects — CURRENT_USER and CURRENT_ROLE.

If the GLOBAL clause is present, then the mapping will be applied not only for the current database, but for all databases in the same cluster, including security databases.

Warning

There can be global and local mappings with the same name.They are distinct objects.
Note

Global mapping works best if a Firebird 3.0 or higher version database is used as the security database.If you plan to use another database for this purpose — using your own provider, for example — then you should create a table in it named RDB$MAP, with the same structure as RDB$MAP in a Firebird 3.0 or higher database and with SYSDBA-only write access.

The USING clause describes the mapping source.It has a complex set of options:

  • an explicit plugin name (PLUGIN plugin_name) means it applies only for that plugin

  • it can use any available plugin (ANY PLUGIN);although not if the source is the product of a previous mapping

  • it can be made to work only with server-wide plugins (SERVERWIDE)

  • it can be made to work only with previous mapping results (MAPPING)

  • you can omit to use of a specific method by using the asterisk (*) argument

  • it can specify the name of the database that defined the mapping for the FROM object (IN database)

    Note

    This argument is not valid for mapping server-wide authentication.

The FROM clause describes the object to map.The FROM clause has a mandatory argument, the type of the object named.It has the following options:

  • When mapping names from plugins, type is defined by the plugin

  • When mapping the product of a previous mapping, type can be only USER or ROLE

  • If an explicit from_name is provided, it will be taken into account by this mapping

  • Use the ANY keyword to work with any name of the given type.

The TO clause specifies the user or role that is the result of the mapping.The to_name is optional.If it is not specified, then the original name of the mapped object will be used.

For roles, the role defined by a mapping rule is only applied when the user does not explicitly specify a role on connect.The mapped role can be assumed later in the session using SET TRUSTED ROLE, even when the mapped role is not explicitly granted to the user.

Who Can Create a Mapping

The CREATE MAPPING statement can be executed by:

  • Administrators

  • The database owner — if the mapping is local

  • Users with the CHANGE_MAPPING_RULES system privilege — if the mapping is local