Sentry Policy File Authorization
The following topics provide instructions on how to install, upgrade, and configure policy file authorization.
The sections that follow contain notes on creating and maintaining the policy file, and using URIs to load external data and JARs.
Storing the Policy File
Considerations for storing the policy file(s) in HDFS include:
- Replication count - Because the file is read for each query in Hive and read once every five minutes by all Impala daemons, you should increase this value; since it is a small file, setting the replication count equal to the number of client nodes in the cluster is reasonable.
- Updating the file - Updates to the file are reflected immediately, so you should write them to a temporary copy of the file first, and then replace the existing file with the temporary one after all the updates are complete. This avoids race conditions caused by reads on an incomplete file.
role1 = privilege1 role1 = privilege2Role names are scoped to a specific file. For example, if you give role1 the ALL privilege on db1 in the global policy file and give role1 ALL on db2 in the per-db db2 policy file, the user will be given both privileges.
Any command which references a URI such as CREATE TABLE EXTERNAL, LOAD, IMPORT, EXPORT, and more, in addition to CREATE TEMPORARY FUNCTION requires the URI privilege. This is an important security control because without this users could simply create an external table over an existing table they do not have access to and bypass Sentry.
URIs must start with either hdfs:// or file://. If a URI starts with anything else, it will cause an exception and the policy file will be invalid.
data_read = server=server1->uri=file:///path/to/dir,\ server=server1->uri=hdfs://namenode:port/path/to/dir
- Load data from a local/NFS directory:
- Load data from HDFS (MapReduce, Pig, and so on):
In addition to the privilege in Sentry, the hive or impala user will require the appropriate file permissions to access the data being loaded. Groups can be used for this purpose. For example, create a group hive-users, and add the hive and impala users along with the users who will be loading data, to this group.
$ groupadd hive-users $ usermod -G someuser,hive-users someuser $ usermod -G hive,hive-users hive
External tables require the ALL@database privilege in addition to the URI privilege. When data is being inserted through the EXTERNAL TABLE statement, or is referenced from an HDFS location outside the normal Hive database directories, the user needs appropriate permissions on the URIs corresponding to those HDFS locations. This means that the URI location must either be owned by the hive:hive user OR the hive/impala users must be members of the group that owns the directory.
[roles] someuser_home_dir_role = server=server1->uri=hdfs://ha-nn-uri/user/someuserYou should now be able to create an external table:
CREATE EXTERNAL TABLE ... LOCATION 'hdfs://ha-nn-uri/user/someuser/mytable';
Sample Sentry Configuration Files
This section provides a sample configuration.
The following is an example of a policy file with a per-DB policy file. In this example, the first policy file, sentry-provider.ini would exist in HDFS; hdfs://ha-nn-uri/etc/sentry/sentry-provider.ini might be an appropriate location. The per-DB policy file is for the customer's database. It is located at hdfs://ha-nn-uri/etc/sentry/customers.ini.
[databases] # Defines the location of the per DB policy file for the customers DB/schema customers = hdfs://ha-nn-uri/etc/sentry/customers.ini [groups] # Assigns each Hadoop group to its set of roles manager = analyst_role, junior_analyst_role analyst = analyst_role jranalyst = junior_analyst_role customers_admin = customers_admin_role admin = admin_role [roles] # The uris below define a define a landing skid which # the user can use to import or export data from the system. # Since the server runs as the user "hive" files in that directory # must either have the group hive and read/write set or # be world read/write. analyst_role = server=server1->db=analyst1, \ server=server1->db=jranalyst1->table=*->action=select server=server1->uri=hdfs://ha-nn-uri/landing/analyst1 junior_analyst_role = server=server1->db=jranalyst1, \ server=server1->uri=hdfs://ha-nn-uri/landing/jranalyst1 # Implies everything on server1 -> customers. Privileges for # customers can be defined in the global policy file even though # customers has its only policy file. Note that the Privileges from # both the global policy file and the per-DB policy file # are merged. There is no overriding. customers_admin_role = server=server1->db=customers # Implies everything on server1. admin_role = server=server1
[groups] manager = customers_insert_role, customers_select_role analyst = customers_select_role [roles] customers_insert_role = server=server1->db=customers->table=*->action=insert customers_select_role = server=server1->db=customers->table=*->action=select
Sentry Configuration File
The following is an example of a sentry-site.xml file.
<configuration> <property> <name>hive.sentry.provider</name> <value>org.apache.sentry.provider.file.HadoopGroupResourceAuthorizationProvider</value> </property> <property> <name>hive.sentry.provider.resource</name> <value>/path/to/authz-provider.ini</value> <!-- If the hdfs-site.xml points to HDFS, the path will be in HDFS; alternatively you could specify a full path, e.g.: hdfs://namenode:port/path/to/authz-provider.ini file:///path/to/authz-provider.ini --> </property> <property> <name>sentry.hive.server</name> <value>server1</value> </property> </configuration>
Accessing Sentry-Secured Data Outside Hive/Impala
However, there are scenarios where fully vetted and reviewed jobs will also need to access the data stored in the Hive warehouse. A typical scenario would be a secured MapReduce transformation job that is executed automatically as an application user. In such cases it's important to know that the user executing this job will also have full access to the data in the Hive warehouse.
Scenario One: Authorizing Jobs
A reviewed, vetted, and automated job requires access to the Hive warehouse and cannot use Hive/Impala to access the data.
Create a group which contains hive, impala, and the user executing the automated job. For example, if the etl user is executing the automated job, you can create a group called hive-users which contains the hive, impala, and etl users.
$ groupadd hive-users $ usermod -G hive,impala,hive-users hive $ usermod -G hive,impala,hive-users impala $ usermod -G etl,hive-users etlOnce you have added users to the hive-users group, change directory permissions in the HDFS:
$ hadoop fs -chgrp -R hive:hive-users /user/hive/warehouse $ hadoop fs -chmod -R 770 /user/hive/warehouse
Scenario Two: Authorizing Group Access to Databases
One group of users, grp1 should have full access to the database, db1, outside of Sentry. The database, db1 should not be accessible to any other groups, outside of Sentry. Sentry should be used for all other authorization needs.
$ usermod -G hive,impala,grp1 hive $ usermod -G hive,impala,grp1 impalaThen change group ownerships of all directories and files in db1 to grp1, and modify directory permissions in the HDFS. This example is only applicable to local groups on a single host.
$ hadoop fs -chgrp -R hive:grp1 /user/hive/warehouse/db1.db $ hadoop fs -chmod -R 770 /user/hive/warehouse/db1.db
Debugging Failed Sentry Authorization Requests
- In Cloudera Manager, add log4j.logger.org.apache.sentry=DEBUG to the logging settings for your service through the corresponding Logging Safety Valve field for the Impala, Hive Server 2, or Solr Server services.
- On systems not managed by Cloudera Manager, add log4j.logger.org.apache.sentry=DEBUG to the log4j.properties file on each host in the cluster, in the appropriate configuration directory for each service.
FilePermission server..., RequestPermission server...., result [true|false]which indicate each evaluation Sentry makes. The FilePermission is from the policy file, while RequestPermission is the privilege required for the query. A RequestPermission will iterate over all appropriate FilePermission settings until a match is found. If no matching privilege is found, Sentry returns false indicating "Access Denied" .