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HBase, Phoenix And Ranger

In Part 1, Part 2 and Part3 of this article series , we discussed internals of Phoenix Index maintenance and major issues hit around this feature. In this article we will discuss about Phoenix - Ranger relationship , how it works and what had broken until recently which caused reporting of several issues.

How native HBase authorization work:

ACLs in HBase are implemented as a coprocessor called AccessController. (hbase.security.authorization=true). Users are granted specific permissions such as Read, Write, Execute, Create, Admin against resources such as global, namespaces, tables, cells, or endpoints. ( all self explanatory)

There is an additional user called “Superuser”. Superusers can perform any operation available in HBase, to any resource. The user who runs HBase on your cluster is a superuser, as are any principals assigned to the configuration property hbase.superuser in hbase-site.xml.

Much more details on this subject are here

How things Changed with Ranger HBase plugin enabled ?

Once Ranger is involved, one can create policies for HBase from Ranger Policy Manager or via Grant / Revoke commands from HBase shell only. These Grant / Revoke commands are mapped to ranger policies and Ranger intercepting appropriate commands from hbase shell adds or edits ranger policies according to user/group and resource information provided in command. And of course, the user running these commands must be an admin user.

It has been seen that using grant / revoke commands which are mapped with Ranger create multiple issues and creation of redundant or conflicting policies. Thus we have an option to disable this feature completely and allow use of only Ranger Policy Manager to manage permissions.

You can disable the command route by setting following parameter in Ranger configs (ranger-hbase-security.xml):

<property>  <name>xasecure.hbase.update.xapolicies.on.grant.revoke</name>  
<value>false</value>  
<description>  Should HBase plugin update Ranger policies for updates to permissions done using GRANT/REVOKE?  </description>  </property>



How it works in Phoenix with Ranger:

Simply put, having a Phoenix table means an existence of HBase table as well and therefore any permissions required to access that HBase table are also required for this Phoenix table.

But this not a complete truth, Phoenix has something called as SYSTEM tables which manage table metadata, and thus users also need to have sufficient permissions on these system tables to be able to login to Phoenix shell, view, create, delete tables etc.

By design, only the first ever user connecting to Phoenix needs the CREATE permission on all SYSTEM tables. This is a first-time operation so that system tables get created if not created already. For every other time, regular users should require READ on the system tables. For users requiring to create tables in Phoenix would need WRITE as well.

But this functionality broke due to PHOENIX-3652 (partly fixed in HDP 2.6.1) and other ranger level complexities and due to this Phoenix expected full permissions on system tables. Users observed any of the following exceptions either during phoenix shell launch or during any DDL operation:

Error: org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions (user=test@HWX.COM scope=SYSTEM:CATALOG, family=0:SALT_BUCKETS, params=[table=SYSTEM:CATALOG,family=0:SALT_BUCKETS],action=WRITE) 

OR

Error: org.apache.hadoop.hbase.security.AccessDeniedException: org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions for user 'test@EXAMPLE.COM' (action=admin) 


To get this working temporarily, users created a policy in ranger and gave all access to these system tables as follows:

  1. Table : SYSTEM.*
  2. Column Family : *
  3. Column : *
  4. Groups : public
  5. Permissions : Read, Write, Create, Admin

Now this was all good in an ideal world, but in real world it raises lot of security issues, customers do not want users to have all access on these system tables due to the obvious fear of manipulation on user tables and their metadata.

To take care of this concern, our developers started working on PHOENIX-4198 (fix available with HDP 2.6.3) where there would be a need for giving only RX permissions on SYSTEM.CATALOG table and rest of the authorization part would be done by a coprocessor endpoint querying either Ranger or native HBase ACLs appropriately. Important to know that this feature does not support working with Ranger yet. (Work In Progress)

However, above feature was specifically designed for system.catalog and users reported issues for system.stats as well where write permissions to users were required in order to drop a table. This has been reported in PHOENIX-4753 and the issue is still unresolved. You may see following exceptions:

org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions (user=user01t01@EXAMPLE.COM, scope=SYSTEM:STATS, family=0:, params=[table=SYSTEM:STATS,family=0:],action=WRITE)

Here again, workaround would be to give this user or group a write permission to system.stats.

grant '@group', 'RWX' , 'SYSTEM:STATS'

Also See : Part 1, Part 2 , Part3

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‎11-17-2018 01:22 AM
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