Shahzad Bhatti

January 10, 2010

PlexRBAC: an open source project for providing powerful role based security (I)

Filed under: Computing — admin @ 7:45 pm

Overview

In my last blog I described core pieces of a security system and mentioned a new open source project PlexRBAC I recently started to provide Role Based Security both as a REST service and Java library. In this post, I will go over the some of the features that are now available. This project is based on my experience with a number of home built solutions for RBAC and standard J2EE solutions. However, a key differentiator is that it adds instance based security or context based security that adds dynamic access control. The role based security consists of following components:

Domain

Though, domain is strictly not part of role based security but RBAC provides segregation of security policies by domains, where a domain can represent a security realm or an application.

Subject

The subject represents users who are defined in an application.

Role

A role represents job title or function. A subject or user belongs to one or more roles. One of key feature of PlexRBAC is that roles support inheritance where a role can have one or more roles. This helps define security policies that follow “don’t repeat yourself” or DRY.

Permission

A permission consists of two sub parts: operation and target, where operation is a “verb” that describes action and target represents “object” that is acted upon. All permissions are assigned to roles. In PlexRBAC, permissions also contains an expression which is evaluated to check dynamic security. PlexRBAC allows Javascript based expressions and provides access to runtime request parameters. Finally, PlexRBAC offers regular expressions for both operations and target, so you can define operations like “(read|write|create|delete)” or “read*”, etc.

Following diagram shows the relationship between these components:

Getting Started

PlexRBAC depends on Java 1.6+ and Maven 2.0+. You can download the project using git:

 git clone git@github.com:bhatti/PlexRBAC.git
 

Then you can start the REST based web service within Jetty by typing:

 mvn jetty:run-war
 

The service will listen on port 8080 and you can test it with curl.

Authentication

Though, PlexRBAC is not designed for authentication but it provides Basic authentication and all administration APIs are protected with the authentication. By default, it uses an account “super_admin” with password “changeme”, which you can modify with configurations. Also, as PlexRBAC supports domains to segregates security policies, subjects are also restricted to the domains where they are defined.

REST APIs

Following are APIs defined in PlexRBAC:

Domains

  • GET /api/security/domains – returns list of all domains in JSON format.
  • GET /api/security/domains/{domain-id} – returns details of given domain in JSON format.
  • PUT /api/security/domains/{domain-id} with body of domain details in JSON format.
  • DELETE /api/security/domains – deletes all domains.
  • DELETE /api/security/domains/{domain-id} – deletes domain identified by domain-id.

Subjects

  • GET /api/security/subjects/{domain-id} – returns list of all subjects in domain identified by domain-id in JSON format.
  • GET /api/security/subjects/{domain-id}/{id} – returns details of given subject identified by id in given domain.
  • PUT /api/security/subjects/{domain-id}/{id} with body of subject details in JSON format.
  • DELETE /api/security/subjects/{domain-id} – deletes all subjects in given domain.
  • DELETE /api/security/subjects/{domain-id}/{id} – deletes subject identified by id.

Roles

  • GET /api/security/roles/{domain-id} – returns list of all roles in domain identified by domain-id in JSON format.
  • GET /api/security/roles/{domain-id}/{id} – returns details of given role identified by id in given domain.
  • PUT /api/security/roles/{domain-id}/{id} with body of role details in JSON format.
  • DELETE /api/security/roles/{domain-id} – deletes all roles in given domain.
  • DELETE /api/security/roles/{domain-id}/{id} – deletes role identified by id.

Permissions

  • GET /api/security/permissions/{domain-id} – returns list of all permissions in domain identified by domain-id in JSON format.
  • GET /api/security/permissions/{domain-id}/{id} – returns details of given permission identified by id in given domain.
  • POST /api/security/permissions/{domain-id} with body of permission details in JSON format. Note that this API uses POST instead of PUT as the id will be assigned by the server.
  • DELETE /api/security/permissions/{domain-id} – deletes all permissions in given domain.
  • DELETE /api/security/permissions/{domain-id}/{id} – deletes permission identified by id.

Mapping of Roles and Permissions

  • PUT /api/security/role_perms/{domain-id}/{role-id} – adds permissions identified by permissionIds that stores list of permission-ids in JSON format. Note that permissionIds is passed as a form parameter.
  • DELETE /api/security/role_perms/{domain-id}/{role-id} – removes permissions identified by permissionIds that stores list of permission-ids in JSON format. Note that permissionIds is passed as a form parameter.

Mapping of Subjects and Roles

  • PUT /api/security/subject_roles/{domain-id}/{subject-id} – adds roles identified by rolenames that stores list of role-ids in JSON format. Note that rolenames is passed as a form parameter.
  • DELETE /api/security/subject_roles/{domain-id}/{subject-id} – removes roles identified by rolenames that stores list of role-ids in JSON format. Note that rolenames is passed as a form parameter.

Authorization

  • GET /api/security/authorize/{domain-id} – with query parameter of operation and target.

Example

Let’s start with a banking example where a bank-object can be account, general-ledger-report or ledger-posting-rules and account is further grouped into customer account or loan account, e.g.

Let’s assume there are five roles: Teller, Customer-Service-Representative (CSR), Account, AccountingManager and LoanOfficer, where

  • A teller can modify customer deposit accounts.
  • A customer service representative can create or delete customer deposit accounts.
  • An accountant can create general ledger reports.
  • An accounting manager can modify ledger-posting rules.
  • A loan officer can create and modify loan accounts.

Creating a domain

The first thing is to create a security domain for your application. As we are dealing with banking domain, let’s call our domain “banking”.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/domains/banking" -d '{"id":"banking"}'
 

It will return response:

 {"id":"banking","ownerSubjectNames":"super_admin"}
 

The first thing to note that we are passing user and password using Basic authentication as all accesses to administration APIs require login. Now, you can find out available domains via

 curl -v --user "super_admin:changeme" "http://localhost:8080/api/security/domains"
 

which would return something like:

 [{"id":"banking","ownerSubjectNames":"super_admin"},{"description":"default","id":"default","ownerSubjectNames":"super_admin"}]
 

Creating Users

Next step is to create users for the domain or application so let’s define accounts for tom, cassy, ali, mike and larry, i.e.,

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subjects/banking" -d '{"id":"tom","credentials":"pass"}'
 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subjects/banking" -d '{"id":"cassy","credentials":"pass"}'
 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subjects/banking" -d '{"id":"ali","credentials":"pass"}'
 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subjects/banking" -d '{"id":"mike","credentials":"pass"}'
 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subjects/banking" -d '{"id":"larry","credentials":"pass"}'
 

Note that each user is identified by an id or username and credentials and in above examples usernames or subject-ids are prefixed with domain-ids, e.g. “ddefault:super_admin”.

Creating Roles

As I mentioned, a role represents job title or responsibilities and each role can have one or more parents. By default, PlexRBAC defines an “anonymous” role, which is used for users who are not logged in and all user-defined roles extend “anonymous” role.

First, we create a role for bank employee called “Employee”:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"Employee"}'
 

which returns

 {"id":"Employee","parentIds":["anonymous"]}
 

As you can see the “Employee” role is created with parent of “anonymous”. Next, we create “Teller” role:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"Teller","parentIds":["Employee"]}'
 

which returns:

 {"id":"Teller","parentIds":["Employee"]}
 

Then we create a role for customer-service-representative called “CSR” that is extended by Teller e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"CSR","parentIds":["Teller"]}' 
 

which returns:

 {"id":"CSR","parentIds":["Teller"]}
 

Then we create a role for “Accountant”:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"Accountant","parentIds":["Employee"]}' 
 

which returns:

 {"id":"Accountant","parentIds":["Employee"]}
 

Then we create a role for “AccountingManager”, which is extended by “Accountant”, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"AccountingManager","parentIds":["Accountant"]}' 
 

which returns:

 {"id":"AccountingManager","parentIds":["Accountant"]}
 

Finally, we create a role for “LoanOfficer”, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/roles/banking" -d '{"id":"LoanOfficer","parentIds":["Employee"]}' 
 

which returns:

 {"id":"LoanOfficer","parentIds":["Employee"]}
 

Creating Permissions

As described above, a permission is composed of operation, target and expression, where an operation and target can be any regular expression and expression can be any Javascript expression. However following permissions don’t define any expressions for simplicity. First, we create a permission to create or delete deposit-account, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(create|delete)","target":"DepositAccount","expression":""}' 
 

which returns:

 {"expression":"","id":"1","operation":"(create|delete)","target":"DepositAccount"}
 

Each permission is automatically assigned a unique numeric id. Next, we create a permission to read or modify deposit-account, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(read|modify)","target":"DepositAccount","expression":""}' 
 

which returns:

 {"expression":"","id":"2","operation":"(read|modify)","target":"DepositAccount"}
 

Then, we create a permission to create or delete loan-account

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(create|delete)","target":"LoanAccount","expression":""}' 
 

which returns:

 {"expression":"","id":"3","operation":"(create|delete)","target":"LoanAccount"}
 

Then we create a permission to read or modify loan-account, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(read|modify)","target":"LoanAccount","expression":""}' 
 

which returns:

 {"expression":"","id":"4","operation":"(read|modify)","target":"LoanAccount"}
 

Then we create a role to view and create general-ledger, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(read|create)","target":"GeneralLedger","expression":""}' 
 

which returns:

 {"expression":"","id":"5","operation":"(read|create)","target":"GeneralLedger"}
 

Finally, we create a permission for modifying posting rules of general-ledger, e.g.

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X POST "http://localhost:8080/api/security/permissions/banking" -d '{"operation":"(read|create|modify|delete)","target":"GeneralLedgerPostingRules","expression":""}' 
 

which returns:

 {"expression":"","id":"6","operation":"(read|create|modify|delete)","target":"GeneralLedgerPostingRules"}
 

Mapping Permissions to Roles

Next task is to map permissions to roles. First we assign permission to view or modify customer deposit accounts to Teller role:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/role_perms/banking/Teller" -d 'permissionIds=["2"]'
 

which returns all permission-ids for given role, e.g.

 ["2"]
 

Then we assign permission to view, create, modify or delete customer deposit accounts to CSR (as CSR extends Teller it will automatically will get all permissions of Teller):

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/role_perms/banking/CSR" -d 'permissionIds=["1"]'
 

Then we assign permissions to create general ledger to Accountant:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/role_perms/banking/Accountant" -d 'permissionIds=["5"]'
 

Then we assign permission to modify ledger-posting rules to AccountingManager:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/role_perms/banking/AccountingManager" -d 'permissionIds=["6"]' 
 

Mapping Users to Roles

A role is associated with one or more permissions and each user is assigned one or more role. First, we assign subject “tom” to Teller role:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subject_roles/banking/tom" -d 'rolenames=["Teller"]'
 

which returns list of all roles for given subject or user, e.g.

 ["Teller"]
 

Then we assign subject “cassy” to CSR role:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subject_roles/banking/cassy" -d 'rolenames=["CSR"]'
 

Next we assign subject “ali” to role of Accountant:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subject_roles/banking/ali" -d 'rolenames=["Accountant"]'
 

Then we assign role AccountingManager to “mike”:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subject_roles/banking/mike" -d 'rolenames=["AccountingManager"]'
 

Finally we assign subject “larry” to LoanOfficer role:

 curl -H "Content-Type: application/json" --user "default:super_admin:changeme" -X PUT "http://localhost:8080/api/security/subject_roles/banking/larry" -d 'rolenames=["LoanOfficer"]'
 

Authorization

Now we are ready to validate authorization based on above security policies. For example, let’s check if user “tom” can view deposit-accounts, e.g.

 curl -v --user "banking:tom:pass" "http://localhost:8080/api/authorize/banking?operation=read&target=DepositAccount"
 

On successful authorization, the API returns 200 http responose-code and on failure it returns 401 http response-code, e.g.

 < HTTP/1.1 200 OK
 

Then we check if tom, the teller can delete deposit-account, e.g.

 curl -v --user "banking:tom:pass" "http://localhost:8080/api/authorize/banking?operation=delete&target=DepositAccount"
 

which returns http-response-code 401, e.g.

 < HTTP/1.1 401 Unauthorized
 

Then we create if cassy, the CSR can delete deposit-account, e.g.

 curl -v --user "banking:cassy:pass" "http://localhost:8080/api/authorize/banking?operation=delete&target=DepositAccount"
 

which returns:

 < HTTP/1.1 200 OK
 

Then we check if ali, the accountant can view general-ledger, e.g.

 curl -v --user "banking:ali:pass" "http://localhost:8080/api/authorize/banking?operation=read&target=GeneralLedger"
 

which returns:

 < HTTP/1.1 200 OK
 

Next we check if mike, the accounting-manager can create general-ledger, e.g.

 curl -v --user "banking:mike:pass" "http://localhost:8080/api/authorize/banking?operation=create&target=GeneralLedger"
 

which returns:

 < HTTP/1.1 200 OK
 

Then we check if larry, the loan officer can create posting-rules of general-ledger, e.g.

 curl -v --user "banking:mike:pass" "http://localhost:8080/api/authorize/banking?operation=create&target=GeneralLedgerPostingRules"
 

which returns:

 < HTTP/1.1 200 OK
 

Next, ali tries to create posting rules via

 curl -v --user "banking:ali:pass" "http://localhost:8080/api/authorize/banking?operation=create&target=GeneralLedgerPostingRules"
 

which is denied:

 < HTTP/1.1 401 Unauthorized
 

Summary

Above examples demonstrate how PlexRBAC can be used to define and enforce flexible security policies. In next post, I will describe instance based security, regular expressions and Java APIs for PlexRBAC.

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