Protecting Action Sequences

In a software system, you can secure elements of that system at different levels, depending on your needs. In a web application, you can secure specific URLs. Deeper in the application you might want to secure specific service method calls. And finally, you might want to secure particular instances of objects. This page talks about the last type of security. Users of the Pentaho platform might wish to have a very precise level of control over objects in their solution repository. The Pentaho BI Platform provides this control.

SecurityUtils

SecurityUtils is an important class because it shields client code from the complexity of the security implementation (e.g. voters, ACL holders, etc). Below is a class diagram along with the two clients that use SecurityUtils for authorization purposes.

Access Control Lists

In the Pentaho BI Platform, objects in the solution repository (e.g. files and directories) can be secured using access control lists (ACLs). You can have any number of entries in an ACL--each specifying a different recipient.

ACL Entries

An entry in an access control list consists of a recipient, permissions, a reference to the object to which the ACL entry applies, and optionally the parent of the object to which the ACL entry applies. The default ACL entry type in Pentaho is PentahoAclEntry. This class extends AbstractBasicAclEntry ^Acegi.

Recipients

PentahoAclEntry stores a recipient as an Object. In practice, recipients can be of two types: a String containing a username or a GrantedAuthority containing a granted authority.

Permissions

PentahoAclEntry stores permissions using bit masks.

Objects and Parents

PentahoAclEntry stores an object (and its parent) as a AclObjectIdentity ^Acegi.

ACL Holders

An IAclHolder does exactly what its name implies--it holds or contains an access control list. An ACL is implemented in the platform using a java.util.List. Inside this list are implementations of AclEntry ^Acegi

Solution Repository Objects

Once you have a container for an ACL, how is it associated with objects in the solution repository? That is where the interface IAclSolutionFile comes in. This interface extends IAclHolder and is implemented by com.pentaho.repository.dbbased.solution.RepositoryFile. RepositoryFile also implements AclObjectIdentity. So not only does a RepositoryFile store an ACL (since it implements IAclHolder), it also is a securable object (since it implements AclObjectIdentity).

Persistence

The Pentaho BI Platform uses Hibernate for reading and writing to the db-based repository. The PRO_FILES table contains solution repository objects while the PRO_ACLS_LIST table contains ACL entries associated with those objects. Below are (incomplete) listings of the columns of each of these tables.

PRO_FILES Table

FILE_ID is the primary key. PARENT is a reference (by file id) to the object's parent. DIRECTORY is a boolean that is true if this object is a directory and false if this object is a file.

PRO_ACLS_LIST Table

Technically, rows in this table represent ACL entries, not ACLs. An ACL for an object can be created by querying for all rows sharing the same ACL_ID. ACL_ID is a foreign key that references PRO_FILES.FILE_ID. ACL_MASK is the decimal representation of the bit mask that represents the permissions in this ACL entry. And RECIPIENT is the username or granted authority that is the recipient of this ACL entry.

Voters

For every domain object, there is exactly one access control list. Add to that a user that wants to perform some operation on that object and that adds up to three inputs: a recipient, an operation, and an ACL. But what makes the "access granted" or "access denied" decision given these three pieces of information? The answer to that question is an IAclVoter. An instance of IAclVoter contains an all-important hasAccess method. It takes the three aforementioned inputs and returns a boolean result: true meaning access granted and false meaning access denied. An ACL voter is a singleton; there is only one instance per Java virtual machine. It is specified in pentaho.xml.

One might ask: How many ways can a voter arrive at a decision? Assume that user sally has the following granted authorities: ROLE_DEV and ROLE_MGR. Also assume that the ACL for a particular object contains the following entries: (sally, read), (ROLE_DEV, readwrite). Both ACL entries are applicable to sally since the first specifies sally (and she is sally) and the second specifies ROLE_DEV (and she has been granted the ROLE_DEV authority). Should the voter grant or deny a request to write to the object associated with this ACL? This is where extensibility of the voting system comes in. The Pentaho BI Platform provides multiple implementations of IAclVoter that each make different decisions in this situation! As the user of the platform, you decide how access decisions are made through your choice of IAclVoter. For more information about IAclVoter implementations, see 12. IAclVoter Node.

ACL Management

ACLs can be managed using a graphical interface that is accessed via the Admin menu. Once on the Admin menu, click Permissions to start the manager.

Note that in order to access the Permissions Editor, you must be logged in as an administrator to the platform. Also, ACLs are only available if you are using the RDBMS solution repository. This feature is not available for the file-based solution repository implementation.

In the screenshot above, the tree on the left represents all of the solution repository objects in your solution repository. You can set permissions on any level in the solution repository object tree. Setting permissions on lower level objects in the tree overrides permission settings higher in the tree. Conversely, if you set a permission on a solution repository object that has children, and the children do not have specific permissions set, they inherit the permissions settings from their parent. So, for example, if I set execute permissions for JoeUser on the analysis object, then the query1.xaction object inherits that execute permission. However, if I then set write and execute permission on the query1.xaction for JoeUser, these permissions are honored for that object, but other children of the analysis object would still only have their parent's (analysis) execute permission.

Today, there are only two permissions available, write and execute. Note that if you set write permission for an object, they automatically will get execute permission as well. Write permission allows the assigned user or role to edit the solution repository object, currently enforced through the platform client tools (Report Design Wizard, Report Designer and Cube Designer). Execute permission allows the user or role to execute the solution repository object, applicable to action sequences.

Each solution repository object can have any number of permission-role or permission-user combinations set. The
middle panel in the screenshot above lists the access control list entries defined for the solution repository object selected in the tree. You can modify the permissions for the roles or users that are defined in the existing access control list entries:

1. Check or uncheck the box for the permission you wish to remove or grant, next to the role or user that you wish this change to be applicable to.
2. Click the Update... button to submit the change.
3. Clicking the Reset button will reverse any changes that have NOT YET been submitted.

To add a new access control list entry, follow these steps:

1. Click the Add button under the access control list entry table. You will see a new list appear on the right, that lists all roles and users available to the system.
2. Select the roles and/or users that you wish to grant permissions to, and then select the permissions that you would like them to recieve.
3. Click the Add button at the bottom of the New Permission panel to add your newly defined access control list entries.

ACL Publishing

The db-based solution repository is refreshed from the filesystem. In other words, solution repository objects are created as files on the filesystem and those objects are refreshed (published) in the db-based solution repository. In the filesystem, solution repository objects have no associated ACLs--at least as far as the platform is concerned. But once solution repository objects are published to the db-based repository, they do have associated ACLs. So how did the objects get their ACLs? The answer is an IAclPublisher. There is only one IAclPublisher instance per JVM and the type of that instance is specified in pentaho.xml. For more information about IAclPublisher implementations, see 13. IAclPublisher Node.

Note that an IAclPublisher is only responsible for the initial publishing of ACLs. After the filesystem is initially published, the Admin > Permissions interface should be used to tweak permissions.