Overview of Impala Security
Impala includes a fine-grained authorization framework for Hadoop, based on the Sentry open source project. Sentry authorization was added in Impala 1.1.0. Together with the Kerberos authentication framework, Sentry takes Hadoop security to a new level needed for the requirements of highly regulated industries such as healthcare, financial services, and government. Impala also includes an auditing capability; Impala generates the audit data, the Cloudera Navigator product consolidates the audit data from all nodes in the cluster, and Cloudera Manager lets you filter, visualize, and produce reports. The auditing feature was added in Impala 1.1.1.
The Impala security features have several objectives. At the most basic level, security prevents accidents or mistakes that could disrupt application processing, delete or corrupt data, or reveal data to unauthorized users. More advanced security features and practices can harden the system against malicious users trying to gain unauthorized access or perform other disallowed operations. The auditing feature provides a way to confirm that no unauthorized access occurred, and detect whether any such attempts were made. This is a critical set of features for production deployments in large organizations that handle important or sensitive data. It sets the stage for multi-tenancy, where multiple applications run concurrently and are prevented from interfering with each other.
The material in this section presumes that you are already familiar with administering secure Linux systems. That is, you should know the general security practices for Linux and Hadoop, and their associated commands and configuration files. For example, you should know how to create Linux users and groups, manage Linux group membership, set Linux and HDFS file permissions and ownership, and designate the default permissions and ownership for new files. You should be familiar with the configuration of the nodes in your Hadoop cluster, and know how to apply configuration changes or run a set of commands across all the nodes.
The security features are divided into these broad categories:
- Which users are allowed to access which resources, and what operations are they allowed to perform? Impala relies on the open source Sentry project for authorization. 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 program, and associates various privileges with each user. See Enabling Sentry Authorization for Impala for details about setting up and managing authorization.
- How does Impala verify the identity of the user to confirm that they really are allowed to exercise the privileges assigned to that user? Impala relies on the Kerberos subsystem for authentication. See Enabling Kerberos Authentication for Impala for details about setting up and managing authentication.
- What operations were attempted, and did they succeed or not? This feature provides a way to look back and diagnose whether attempts were made to perform unauthorized operations. You use this information to track down suspicious activity, and to see where changes are needed in authorization policies. The audit data produced by this feature is collected by the Cloudera Manager product and then presented in a user-friendly form by the Cloudera Manager product. See Auditing Impala Operations for details about setting up and managing auditing.