Impala Authorization

Authorization determines which users are allowed to access which resources, and what operations they are allowed to perform. You use Apache Ranger to enable and manage authorization in Impala.

You set up privileges through the GRANT and REVOKE statements in either Impala or Hive. Then both components use those same privileges automatically.

By default, when authorization is not enabled, Impala does all read and write operations with the privileges of the impala user, which is suitable for a development/test environment but not for a secure production environment. When authorization is enabled, Impala uses the OS user ID of the user who runs impala-shell or other client programs, and associates various privileges with each user.

Privilege Model

Privileges can be granted on different objects in the schema and are associated with a level in the object hierarchy. If a privilege is granted on a parent object in the hierarchy, the child object automatically inherits it. This is the same privilege model as Hive and other database systems.

The objects in the Impala schema hierarchy are:

Server
    URI
    Database
        Table
            Column

The table-level privileges apply to views as well. Anywhere you specify a table name, you can specify a view name instead.

You can specify privileges for individual columns.

The table below lists the minimum level of privileges and the scope required to execute SQL statements in Impala. The following notations are used:

ANY denotes the SELECT, INSERT, CREATE, or REFRESH privilege.
ALL privilege denotes the SELECT, INSERT, CREATE, and REFRESH privileges.
The owner of an object effectively has the ALL privilege on the object.
The parent levels of the specified scope are implicitly supported. For example, if a privilege is listed with the TABLE scope, the same privilege granted on DATABASE and SERVER will allow the user to execute that specific SQL statement on TABLE.

For example, to be able to execute CREATE VIEW, you need the CREATE privilege on the database and the SELECT privilege on the source table.


SQL Statement	Privileges	Object Type / Resource Type
SELECT	SELECT	TABLE
WITH SELECT	SELECT	TABLE
EXPLAIN SELECT	SELECT	TABLE
INSERT	INSERT	TABLE
EXPLAIN INSERT	INSERT	TABLE
TRUNCATE	INSERT	TABLE
LOAD	INSERT	TABLE
LOAD	ALL	URI
CREATE DATABASE	CREATE	SERVER
CREATE DATABASE LOCATION	CREATE	SERVER
CREATE DATABASE LOCATION	ALL	URI
CREATE TABLE	CREATE	DATABASE
CREATE TABLE LIKE	CREATE	DATABASE
CREATE TABLE LIKE	SELECT, INSERT, or REFRESH	TABLE
CREATE TABLE AS SELECT	CREATE	DATABASE
	INSERT	DATABASE
	SELECT	TABLE
EXPLAIN CREATE TABLE AS SELECT	CREATE	DATABASE
	INSERT	DATABASE
	SELECT	TABLE
CREATE TABLE LOCATION	CREATE	TABLE
CREATE TABLE LOCATION	ALL	URI
CREATE VIEW	CREATE	DATABASE
CREATE VIEW	SELECT	TABLE
ALTER DATABASE SET OWNER	ALL WITH GRANT	DATABASE
ALTER TABLE	ALL	TABLE
ALTER TABLE SET LOCATION	ALL	TABLE
ALTER TABLE SET LOCATION	ALL	URI
ALTER TABLE RENAME	CREATE	DATABASE
ALTER TABLE RENAME	ALL	TABLE
ALTER TABLE SET OWNER	ALL WITH GRANT	TABLE
ALTER VIEW	ALL	TABLE
ALTER VIEW	SELECT	TABLE
ALTER VIEW RENAME	CREATE	DATABASE
ALTER VIEW RENAME	ALL	TABLE
ALTER VIEW SET OWNER	ALL WITH GRANT	VIEW
DROP DATABASE	ALL	DATABASE
DROP TABLE	ALL	TABLE
DROP VIEW	ALL	TABLE
CREATE FUNCTION	CREATE	DATABASE
CREATE FUNCTION	ALL	URI
DROP FUNCTION	ALL	DATABASE
COMPUTE STATS	ALL	TABLE
DROP STATS	ALL	TABLE
INVALIDATE METADATA	REFRESH	SERVER
INVALIDATE METADATA <table>	REFRESH	TABLE
REFRESH <table>	REFRESH	TABLE
REFRESH AUTHORIZATION	REFRESH	SERVER
REFRESH FUNCTIONS	REFRESH	DATABASE
COMMENT ON DATABASE	ALL	DATABASE
COMMENT ON TABLE	ALL	TABLE
COMMENT ON VIEW	ALL	TABLE
COMMENT ON COLUMN	ALL	TABLE
DESCRIBE DATABASE	SELECT, INSERT, or REFRESH	DATABASE
DESCRIBE <table/view> If the user has the SELECT privilege at the COLUMN level, only the columns the user has access will show.	SELECT, INSERT, or REFRESH	TABLE
	SELECT	COLUMN
USE	ANY	TABLE
SHOW DATABASES	ANY	TABLE
SHOW TABLES	ANY	TABLE
SHOW FUNCTIONS	SELECT, INSERT, or REFRESH	DATABASE
SHOW PARTITIONS	SELECT, INSERT, or REFRESH	TABLE
SHOW TABLE STATS	SELECT, INSERT, or REFRESH	TABLE
SHOW COLUMN STATS	SELECT, INSERT, or REFRESH	TABLE
SHOW FILES	SELECT, INSERT, or REFRESH	TABLE
SHOW CREATE TABLE	SELECT, INSERT, or REFRESH	TABLE
SHOW CREATE VIEW	SELECT, INSERT, or REFRESH	TABLE
SHOW CREATE FUNCTION	SELECT, INSERT, or REFRESH	DATABASE
SHOW RANGE PARTITIONS (Kudu only)	SELECT, INSERT, or REFRESH	TABLE
UPDATE (Kudu only)	ALL	TABLE
EXPLAIN UPDATE (Kudu only)	ALL	TABLE
UPSERT (Kudu only)	ALL	TABLE
WITH UPSERT (Kudu only)	ALL	TABLE
EXPLAIN UPSERT (Kudu only)	ALL	TABLE
DELETE (Kudu only)	ALL	TABLE
EXPLAIN DELETE (Kudu only)	ALL	TABLE

The privileges not listed in the table above will be silently ignored by Impala.

Changing Privileges in Impala

Privileges are managed via the GRANT and REVOKE SQL statements that require the Ranger service enabled.

Privileges can be also managed in Ranger UI. Especially, for attribute-based access control, Ranger UI is required to manage authorization.

Impala authorization policies are listed in the Hive service section in Ranger UI.

REFRESH AUTHORIZATION is not required when you make the changes to privileges within Impala. The changes are automatically propagated.

Changing Privileges from Outside of Impala

If you make a change to privileges in Ranger from outside of Impala, e.g. adding a user, removing a user, modifying privileges, there are two options to propagate the change:

Use the ranger.plugin.hive.policy.pollIntervalMs property to specify how often to do a Ranger refresh. The property is specified in ranger-hive-security.xml in the conf directory under your Impala home directory.
Run the INVALIDATE METADATA or REFRESH AUTHORIZATION statement to force a refresh.

Granting Privileges on URI

URIs represent the file paths you specify as part of statements such as CREATE EXTERNAL TABLE and LOAD DATA. Typically, you specify what look like UNIX paths, but these locations can also be prefixed with hdfs:// to make clear that they are really URIs. To set privileges for a URI, specify the name of a directory, and the privilege applies to all the files in that directory and any directories underneath it.

URIs must start with hdfs://, s3a://, adl://, or file://. If a URI starts with an absolute path, the path will be appended to the default filesystem prefix. For example, if you specify:


GRANT ALL ON URI '/tmp';

The above statement effectively becomes the following where the default filesystem is HDFS.


GRANT ALL ON URI 'hdfs://localhost:20500/tmp';

When defining URIs for HDFS, you must also specify the NameNode. For example:

GRANT ALL ON URI file:///path/to/dir TO <role>
GRANT ALL ON URI hdfs://namenode:port/path/to/dir TO <role>

warning

Because the NameNode host and port must be specified, it is strongly recommended that you use High Availability (HA). This ensures that the URI will remain constant even if the NameNode changes. For example:

GRANT ALL ON URI hdfs://ha-nn-uri/path/to/dir TO <role>