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Hive Authorization

Hive Client Authorization

This section describes Hive security using the basic authorization scheme, which regulates access to Hive metadata on the client side. Starting with Hive release 0.10, additional security measures can be enabled to regulate access on the metastore side, as described in Metastore Server Security below.

Disclaimer

Hive authorization is not completely secure. The basic authorization scheme is intended primarily to prevent good users from accidentally doing bad things, but makes no promises about preventing malicious users from doing malicious things. Starting in Hive release 0.10, however, metastore-side security can be enabled to prevent malicious access to metadata in a metastore server configuration.

Prerequisites

In order to use Hive authorization, there are two parameters that should be set in hive-site.xml:

<property>
  <name>hive.security.authorization.enabled</name>
  <value>true</value>
  <description>enable or disable the hive client authorization</description>
</property>

<property>
  <name>hive.security.authorization.createtable.owner.grants</name>
  <value>ALL</value>
  <description>the privileges automatically granted to the owner whenever a table gets created. 
   An example like "select,drop" will grant select and drop privilege to the owner of the table</description>
</property>

Note that, by default, the hive.security.authorization.createtable.owner.grants are set to null, which would result in the creator of a table having no access to the table.

Users, Groups, and Roles

At the core of Hive's authorization system are users, groups, and roles. Roles allow administrators to give a name to a set of grants which can be easily reused. A role may be assigned to users, groups, and other roles. For example, consider a system with the following users and groups:

• <User>: <Groups>
• user_all_dbs: group_db1, group_db2
• user_db1: group_db1
• user_db2: group_db2

If we wanted to restrict each user to a specific set of databases, we could use roles to build the authorization mechanism. The administrator would create two roles, called role_db1 and role_db2. The role_db1 role would provide privileges just for the first database, and the role_db2 role would provide privileges just for the second database. The administrator could then grant the role_db1 role to group_db1, or explicitly for the users in the group, and do the same for role_db2 with the users of the second database. In order to allow users who need to see all databases to get their appropriate privileges, a third role could be created called role_all_dbs, which would be granted role_db1 and role_db2. When user_all_dbs is granted the role_all_dbs role, the user implicitly is granted all the privileges of role_db1 and role_db2.

Hive roles must be created manually before being used, unlike users and groups. Users and groups are managed by the hive.security.authenticator.manager. When a user connects to a Metastore Server and issues a query, the Metastore will determine the username of the connecting user, and the groups associated with that ushive.security.authorization.ername. That information is then used to determine if the user should have access to the metadata being requested, by comparing the required privileges of the Hive operation to the user privileges using the following rules:

• User privileges (Has the privilege been granted to the user)
• Group privileges (Does the user belong to any groups that the privilege has been granted to)
• Role privileges (Does the user or any of the groups that the user belongs to have a role that grants the privilege)

By default, the Metastore uses the HadoopDefaultAuthenticator for determing user -> group mappings, which determines authorization by using the Unix usernames and groups on the machine where the Metastore is running. To make this more clear, consider a scenario where a user foo is a member of group bar on the machine running the Hive CLI, and connects to a Metastore running on a separate server that also has a user named foo, but on the Metastore Server, foo is a member of group baz. When an operation is executed, the Metastore will determine foo to be in the group baz.

Taking this a step further, it is also possible for the groups that a user belongs to on the Metastore Server may differ from the groups that the same user belongs to, as determined by HDFS. This could be the case if Hive or HDFS are configured to use non-default user -> group mappers, or the Metastore and the Namenode both use the defaults, but the processes are running on different machines, and the user -> group mappings are not the same on each machine.

It is important to realize that Hive Metastore only controls authorization for metadata, and the underlying data is controlled by HDFS, so if permissions and privileges between the two systems are not in sync, users may have access to metadata, but not the physical data. If the user -> group mappings across the Metastore and Namenode are not in sync, as in the scenarios above, a user may have the privileges required to access a table according to the Metastore, but may not have permission to access the underlying files according to the Namenode. This could also happen due to administrator intervention, if permissions on the files were changed by hand, but Metastore grants had not been updated.

Creating/Dropping/Using Roles

Create/Drop Role

CREATE ROLE role_name

DROP ROLE role_name

Grant/Revoke Roles

GRANT ROLE role_name [, role_name] ...
TO principal_specification [, principal_specification] ...

REVOKE ROLE role_name [, role_name] ...
FROM principal_specification [, principal_specification] ...

principal_specification
  : USER user
  | GROUP group
  | ROLE role

Viewing Granted Roles

SHOW ROLE GRANT principal_specification

Privileges

The following privileges are supported in Hive:

• ALL - Gives users all privileges
• ALTER - Allows users to modify the metadata of an object
• UPDATE - Allows users to modify the physical data of an object
• CREATE - Allows users to create objects. For a database, this means users can create tables, and for a table, this means users can create partitions
• DROP - Allows users to drop objects
• INDEX - Allows users to create indexes on an object (Note: this is not currently implemented)
• LOCK - Allows users to lock or unlock tables when concurrency is enabled
• SELECT - Allows users to access data for objects
• SHOW_DATABASE - Allows users to view available databases

Grant/Revoke Privileges

GRANT
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    [ON object_type]
    TO principal_specification [, principal_specification] ...
    [WITH GRANT OPTION]

REVOKE
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    [ON object_type priv_level]
    FROM principal_specification [, principal_specification] ...

REVOKE ALL PRIVILEGES, GRANT OPTION
    FROM user [, user] ...

object_type:
    TABLE
  | DATABASE

priv_level:
    db_name
  | tbl_name

Viewing Granted Privileges

SHOW GRANT principal_specification
[ON object_type priv_level [(column_list)]]

Hive Operations and Required Privileges

As of the release of Hive 0.7, only these operations require permissions, according to org.apache.hadoop.hive.ql.plan.HiveOperation:

Metastore Server Security

This section describes the metastore server security feature added to Hive in release 0.10. This feature was introduced previously in HCatalog (see Storage Based Authorization).

The Need for Metastore Server Security

When multiple clients access the same metastore in a backing database, such as MySQL, the database connection credentials may be visible in the hive-site.xml configuration file. A malicious or incompetent user could cause serious damage to metadata even though the underlying data is protected by HDFS access controls.

Also, when a Hive metastore server uses Thrift to communicate with clients and has a backing database for metadata storage and persistence, the authentication and authorization done on the client side cannot guarantee security on the metastore side.

To provide security for metadata, release 0.10 adds authorization capability to the metastore. (See HIVE-3705.) Metastore security is based on access rights to the underlying storage system, not on privileges granted to users, groups, and roles.

Configuration Parameters for Metastore Security

To enable Hive metastore server security, set these parameters in hive-site.xml:

• hive.security.metastore.authorization.manager – Set to org.apache.hadoop.hive.ql.security.authorization.DefaultHiveMetastoreAuthorizationProvider.

• hive.security.metastore.authenticator.manager – Set to org.apache.hadoop.hive.ql.security.HadoopDefaultMetastoreAuthenticator.

• hive.metastore.pre.event.listeners – Set to org.apache.hadoop.hive.ql.security.authorization.AuthorizationPreEventListener.

...

Introduction

Note that this documentation is referring to Authorization which is verifying if a user has permission to perform a certain action, and not about Authentication (verifying the identity of the user). Strong authentication for tools like the Hive command line is provided through the use of Kerberos. There are additional authentication options for users of HiveServer2.

Hive Authorization Options

Three modes of Hive authorization are available to satisfy different use cases.

Use Cases

It is useful to think of authorization in terms of two primary use cases of Hive. 

1. Hive as a table storage layer. This is the use case for Hive's HCatalog API users such as Apache Pig, MapReduce and some Massively Parallel Processing databases (Cloudera Impala, Facebook Presto, Spark SQL etc). In this case, Hive provides a table abstraction and metadata for files on storage (typically HDFS). These users have direct access to HDFS and the metastore server (which provides an API for metadata access). HDFS access is authorized through the use of HDFS permissions. Metadata access needs to be authorized using Hive configuration.
2. Hive as a SQL query engine. This is one of the most common use cases of Hive. This is the 'Hive view' of SQL users and BI tools. This use case has the following two subcategories:
   1. Hive command line users. These users have direct access to HDFS and the Hive metastore, which makes this use case similar to use case 1. Note, that usage of Hive CLI will be officially deprecated soon in favor of Beeline.
   2. ODBC/JDBC and other HiveServer2 API users (Beeline CLI is an example). These users have all data/metadata access happening through HiveServer2. They don't have direct access to HDFS or the metastore.

Overview of Authorization Modes

1 Storage Based Authorization in the Metastore Server

In use cases 1 and 2a, the users have direct access to the data. Hive configurations don't control the data access. The HDFS permissions act as one source of truth for the table storage access. By enabling Storage Based Authorization in the Metastore Server, you can use this single source for truth and have a consistent data and metadata authorization policy. To control metadata access on the metadata objects such as Databases, Tables and Partitions, it checks if you have permission on corresponding directories on the file system. You can also protect access through HiveServer2 (use case 2b above) by ensuring that the queries run as the end user (hive.server2.enable.doAs option should be "true" in HiveServer2 configuration – this is a default value).

Note, that through the use of HDFS ACL (available in Hadoop 2.4 onwards) you have a lot of flexibility in controlling access to the file system, which in turn provides more flexibility with Storage Based Authorization. This functionality is available as of Hive 0.14 (HIVE-7583).

While relying on Storage based authorization for restricting access, you still need to enable one of the security options 2 or 3 listed below or use FallbackHiveAuthorizer to protect actions within the HiveServer2 instance.

Fall Back Authorizer

You need to use Hive 2.3.4 or 3.1.1 or later to use Fall Back Authorizer.

Admin needs to specify the following entries in
hiveserver2-site.xml:

<property>
  <name>hive.security.authorization.enabled</name>
  <value>true</value>
</property>
<property>
  <name>hive.security.authorization.manager</name>
  <value>org.apache.hadoop.hive.ql.security.authorization.plugin.fallback.FallbackHiveAuthorizerFactory</value>
</property>

FallbackHiveAuthorizerFactory will do the following to mitigate above mentioned threat:

1. Disallow local file location in sql statements except for admin
2. Allow "set" only selected whitelist parameters
3. Disallow dfs commands except for admin
4. Disallow "ADD JAR" statement
5. Disallow "COMPILE" statement
6. Disallow "TRANSFORM" statement

2 SQL Standards Based Authorization in HiveServer2

Although Storage Based Authorization can provide access control at the level of Databases, Tables and Partitions, it can not control authorization at finer levels such as columns and views because the access control provided by the file system is at the level of directory and files. A prerequisite for fine grained access control is a data server that is able to provide just the columns and rows that a user needs (or has) access to. In the case of file system access, the whole file is served to the user. HiveServer2 satisfies this condition, as it has an API that understands rows and columns (through the use of SQL), and is able to serve just the columns and rows that your SQL query asked for.

SQL Standards Based Authorization (introduced in Hive 0.13.0, HIVE-5837) can be used to enable fine grained access control. It is based on the SQL standard for authorization, and uses the familiar grant/revoke statements to control access. It needs to be enabled through HiveServer2 configuration. 

Note that for use case 2a (Hive command line) SQL Standards Based Authorization is disabled. This is because secure access control is not possible for the Hive command line using an access control policy in Hive, because users have direct access to HDFS and so they can easily bypass the SQL standards based authorization checks or even disable it altogether. Disabling this avoids giving a false sense of security to users.

3 Authorization using Apache Ranger & Sentry

Apache Ranger and Apache Sentry are apache projects that use plugins provided by hive to do authorization.

The policies are maintained under repositories under those projects.

You also get many advanced features using them. For example, with Ranger you can view and manage policies through web interface, view auditing information, have dynamic row and column level access control (including column masking) based on runtime attributes.

4 Old default Hive Authorization (Legacy Mode)

Hive Old Default Authorization (was default before Hive 2.0.0) is the authorization mode that has been available in earlier versions of Hive. However, this mode does not have a complete access control model, leaving many security gaps unaddressed. For example, the permissions needed to grant privileges for a user are not defined, and any user can grant themselves access to a table or database.

This model is similar to the SQL standards based authorization mode, in that it provides grant/revoke statement-based access control. However, the access control policy is different from SQL standards based authorization, and they are not compatible. Use of this mode is also supported for Hive command line users. However, for reasons mentioned under the discussion of SQL standards based authorization (above), it is not a secure mode of authorization for the Hive command line.

Addressing Authorization Needs of Multiple Use Cases

Storage based authorization provides a simple way to address all the use cases described above. However, if you need finer grained access control for SQL users, you can also enable SQL standards based authorization mode in HiveServer2.

That is, you can have storage based authorization enabled for metastore API calls (in the Hive metastore) and have SQL standards based authorization enabled in HiveServer2 at the same time.

Explain Authorization

More Information

For detailed information about the Hive authorization modes, see:

• Storage Based Authorization in the Metastore Server 
  • also see HCatalog Authorization

• SQL Standard Based Hive Authorization 

• Hive deprecated authorization mode / Legacy Mode
  • also see the design document and Security