Shahzad Bhatti

January 20, 2010

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

Filed under: Computing — admin @ 1:50 pm

This is continuation of my previous blog on my open source project PlexRBAC for managing role based access control. Last time, I covered REST APIs and in this blog I will cover internal domain model, RBAC APIs in Java and examples of instance or dynamic based security.

Layers

PlexRBAC consists of following layers

Business Domain Layer

This layer defines core classes that are part of the RBAC based security domain such as:

  • Domain – As described previously, the domain allows you to support multiple applications or realms.
  • Subject – The subject represents users who are defined in an application.
  • Role – A role represents job title or function.
  • Permission – A permission is composed of operation, target and an expression that is used for dynamic or instance based security.
  • SecurityError – Upon a permission failure, you can choose to store them in the database using SecurityError.

Repository Layer

This layer is responsible for accessing or storing above objects in the database. PlexRBAC uses Berkley DB for persistence and each domain is stored as a separate database, which allows you to segregate permissions and roles for distinct domains. Following are list of repositories supported by PlexRBAC:

  • DomainRepository – provides database access for Domains.
  • PermissionRepository – provides database access for Permissions.
  • SubjectRepository – provides database access for Subjects.
  • SecurityErrorRepository – provides database access for SecurityErrors.
  • RoleRepository – provides database access for Roles.
  • SecurityMappingRepository – provides APIs to map permissions with roles and to map subject with roles.
  • RepositoryFactory – provides factory methods to create above repositories.

Security Layer

This class defines PermissionManager for authorizing permissions.

Evaluation Layer

This layer proivdes evaluation engine for instance based security.

Service Layer

This layer defines REST services such as:

  • DomainService – this service provides REST APIs for accessing Domains.
  • PermissionService – this service provides REST APIs for accessing Permissions.
  • SubjectService – this service provides REST APIs for accessing Subjects.
  • RoleService – this service provides REST APIs for accessing Roles.
  • AuthenticationService – this service provides REST APIs for authenticating users.
  • AuthorizationService – this service provides REST APIs for authorizing permissions.
  • RolePermissionService – this service provides REST APIs for mapping permissions with roles.
  • SubjectRolesService – this service provides REST APIs for mapping subjects with roles.

JMX Layer

This layer defines JMX helper classes for managing services and configuration remotely.

Caching Layer

This layer provides caching security permissions to improve performance.

Metrics Layer

This layer provides performance measurement classes such as Timing class to measure method invocation benchmarks.

Utility Layer

This layer provides helper classes.

Web Layer

This layer provides filters for enforcing authentication and authorization when accessing REST APIs.

Example

Let’s use the same example that we described last time but with addition of instance based security. Let’s assume there are five roles: Teller, Customer-Service-Representative (CSR), Account, AccountingManager and LoanOfficer, where

  • A teller can modify customer deposit accounts — but only if customer and teller live in same region
  • A customer service representative can create or delete customer deposit accounts — but only if customer and teller live in same region
  • An accountant can create general ledger reports — but only if year is == current year
  • An accounting manager can modify ledger-posting rules — but only if year is == current year
  • A loan officer can create and modify loan accounts – but only if account balance is < 10000

In addition, following classes will be used to add domain specific security:

  1 
  2 class User {
 
  3 
  4     private String id;
  5     private String region;
  6 
 
  7     User() {
  8     }
  9 
 10     public User(String id, String region) {
 11         this.id = id;
 
 12         this.region = region;
 13     }
 14 
 15     public void setRegion(String region) {
 16         this.region = region;
 
 17     }
 18 
 19     public String getRegion() {
 20         return region;
 21     }
 
 22 
 23     public void setId(String id) {
 24         this.id = id;
 25     }
 26 
 
 27     public String getId() {
 28         return id;
 29     }
 30 }
 31 
 
 32 class Customer extends User {
 33 
 34     public Customer(String id, String region) {
 35         super(id, region);
 
 36     }
 37 }
 38 
 39 class Employee extends User {
 40 
 
 41     public Employee(String id, String region) {
 42         super(id, region);
 43     }
 44 }
 45 
 
 46 class Account {
 47 
 48     private String id;
 49     private double balance;
 
 50 
 51     Account() {
 52     }
 53 
 54     public Account(String id, double balance) {
 
 55         this.id = id;
 56         this.balance = balance;
 57     }
 58 
 59     /**
 
 60      * @return the id
 61      */
 62     public String getId() {
 
 63         return id;
 64     }
 65 
 66     /**
 67      * @param id
 
 68      *            the id to set
 69      */
 70     public void setId(String id) {
 
 71         this.id = id;
 72     }
 73 
 74     public void setBalance(double balance) {
 
 75         this.balance = balance;
 76     }
 77 
 78     public double getBalance() {
 79         return balance;
 
 80     }
 81 }
 82 
 83 
 

Bootstrapping

Let’s create handle to repository-factory as:

 1 
 2     private static final String TEST_DB_DIR = "test_db_dir_perms";
 
 3     RepositoryFactory repositoryFactory = new RepositoryFactoryImpl(TEST_DB_DIR);
 

And instance of permission manager as:

 1 PermissionManager permissionManager = new PermissionManagerImpl(repositoryFactory,
 
 2             new JavascriptEvaluator());
 

Creating a domain

Now, let’s create a domain for banking:

 1     private static final String BANKING = "banking";
 
 2     repositoryFactory.getDomainRepository().save(new Domain(BANKING, ""));
 

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.,

 1         final SubjectRepository subjectRepo = repositoryFactory
 
 2                 .getSubjectRepository(BANKING);
 3         Subject tom = subjectRepo.save(new Subject("tom", "pass"));
 4         Subject cassy = subjectRepo.save(new Subject("cassy", "pass"));
 
 5         Subject ali = subjectRepo.save(new Subject("ali", "pass"));
 6         Subject mike = subjectRepo.save(new Subject("mike", "pass"));
 
 7         Subject larry = subjectRepo.save(new Subject("larry", "pass"));
 8 
 

Creating Roles

Now, we will create roles for Teller, CSR, Accountant, AccountManager and LoanManager:

  1         final RoleRepository roleRepo = repositoryFactory
 
  2                 .getRoleRepository(BANKING);
  3         Role employee = roleRepo.save(new Role("Employee"));
  4         Role teller = roleRepo.save(new Role("Teller", employee));
 
  5         Role csr = roleRepo.save(new Role("CSR", teller));
  6         Role accountant = roleRepo.save(new Role("Accountant", employee));
 
  7         Role accountantMgr = roleRepo.save(new Role("AccountingManager",
  8                 accountant));
  9         Role loanOfficer = roleRepo
 
 10                 .save(new Role("LoanOfficer", accountantMgr));
 11 
 

Creating Permissions

We can then create new permissions and save them in the database as follows:

  1         final PermissionRepository permRepo = repositoryFactory
 
  2                 .getPermissionRepository(BANKING);
  3         Permission cdDeposit = permRepo.save(new Permission("(create|delete)",
  4                 "DepositAccount",
 
  5                 "employee.getRegion().equals(customer.getRegion())")); // 1
  6         Permission ruDeposit = permRepo.save(new Permission("(read|modify)",
  7                 "DepositAccount",
 
  8                 "employee.getRegion().equals(customer.getRegion())")); // 2
  9         Permission cdLoan = permRepo.save(new Permission("(create|delete)",
 10                 "LoanAccount", "account.getBalance() < 10000")); // 3
 
 11         Permission ruLoan = permRepo.save(new Permission("(read|modify)",
 12                 "LoanAccount", "account.getBalance() < 10000")); // 4
 
 13 
 14         Permission rdLedger = permRepo.save(new Permission("(read|create)",
 15                 "GeneralLedger", "year == new Date().getFullYear()")); // 5
 
 16 
 17         Permission rGlpr = permRepo
 18                 .save(new Permission("read", "GeneralLedgerPostingRules",
 19                         "year == new Date().getFullYear()")); // 6
 
 20 
 21         Permission cmdGlpr = permRepo.save(new Permission(
 22                 "(create|modify|delete)", "GeneralLedgerPostingRules",
 23                 "year == new Date().getFullYear()")); // 7
 
 24 
 

Mapping Subjects/Permissions to Roles

Now we will map subjects to roles as follows:

 1         final SecurityMappingRepository smr = repositoryFactory
 
 2                 .getSecurityMappingRepository(BANKING);
 3 
 4         // Mapping Users to Roles
 5         smr.addRolesToSubject(tom, teller);
 6         smr.addRolesToSubject(cassy, csr);
 7         smr.addRolesToSubject(ali, accountant);
 
 8         smr.addRolesToSubject(mike, accountantMgr);
 9         smr.addRolesToSubject(larry, loanOfficer);
 0 
 

Then we will map permissions to roles as follows:

 1         smr.addPermissionsToRole(teller, ruDeposit);
 2         smr.addPermissionsToRole(csr, cdDeposit);
 
 3         smr.addPermissionsToRole(accountant, rdLedger);
 4         smr.addPermissionsToRole(accountant, ruLoan);
 5         smr.addPermissionsToRole(accountantMgr, cdLoan);
 6         smr.addPermissionsToRole(accountantMgr, rGlpr);
 7         smr.addPermissionsToRole(loanOfficer, cmdGlpr);
 8 
 
 

Authorization

Now the fun part of authorization, let’s check if user “tom” can view deposit-accounts, e.g.

  1    public static Map<String, Object> toMap(final Object... keyValues) {
 
  2         Map<String, Object> map = new HashMap<String, Object>();
  3         for (int i = 0; i < keyValues.length - 1; i += 2) {
 
  4             map.put(keyValues[i].toString(), keyValues[i + 1]);
  5         }
  6         return map;
  7     }
 
  8     @Test
  9     public void testReadDepositByTeller() {
 10         initDatabase();
 11         permissionManager.check(new PermissionRequest(BANKING, "tom", "read",
 
 12                 "DepositAccount", toMap("employee", new Employee("tom",
 13                         "west"), "customer", new Customer("zak", "west"))));
 
 14     }
 15 
 16 
 

Note that above test method builds a PermissionRequest that encapsulates domain, subject, operation, target and context and then calls check method of SecurityManager, which throws SecurityException if permission fails.

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

 1     @Test(expected = SecurityException.class)
 
 2     public void testDeleteByTeller() {
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "tom", "delete",
 
 5                 "DepositAccount", toMap("employee", new Employee("tom",
 6                         "west"), "customer", new Customer("zak", "west"))));
 
 7     }
 8 
 

Which would throw security exception.

Now let’s check if cassy, the CSR can delete deposit-account, e.g.

 1     @Test
 2     public void testDeleteByCsr() {
 
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "cassy",
 5                 "delete", "DepositAccount", toMap("employee",
 
 6                         new Employee("cassy", "west"), "customer",
 7                         new Customer("zak", "west"))));
 
 0 
 

Which works as CSR have permissions for deleting deposit-account. Now, let’s check if ali, the accountant can view general-ledger, e.g.

 1    @Test
 2     public void testReadLedgerByAccountant() {
 
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "ali", "read",
 5                 "GeneralLedger", toMap("year", 2010, "account",
 
 6                         new Account("zak", 500))));
 7     }
 8 
 9 
 

Which works as expected. Next we check if ali can delete general-ledger:

 1     @Test(expected = SecurityException.class)
 
 2     public void testDeleteLedgerByAccountant() {
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "ali", "delete",
 
 5                 "GeneralLedger", toMap("year", 2010, "account",
 6                         new Account("zak", 500))));
 7     }
 
 8 
 9 
 

Which would fail as only account-manager can delete. Next we check if mike, the account-manager can create general-ledger, e.g.

 1     @Test
 2     public void testCreateLedgerByAccountantManager() {
 
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "mike",
 5                 "create", "GeneralLedger", toMap("year", 2010,
 
 6                         "account", new Account("zak", 500))));
 7     }
 8 
 

Which works as expected. Now we check if mike can create posting-rules of general-ledger, e.g.

 1     @Test(expected = SecurityException.class)
 
 2     public void testPostLedgingRulesByAccountantManager() {
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "mike",
 
 5                 "create", "GeneralLedgerPostingRules", toMap("year",
 6                         2010, "account", new Account("zak", 500))));
 
 7     }
 8 
 

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

 1     @Test
 2     public void testPostLedgingRulesByLoanManager() {
 
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "larry",
 5                 "create", "GeneralLedgerPostingRules", toMap("year",
 
 6                         2010, "account", new Account("zak", 500))));
 7     }
 8 
 

Which works as expected. Now, let’s check the same permission but with different year, e.g.

 1     @Test(expected = SecurityException.class)
 
 2     public void testPostLedgingRulesByLoanManagerWithExceededAmount() {
 3         initDatabase();
 4         permissionManager.check(new PermissionRequest(BANKING, "larry",
 
 5                 "create", "GeneralLedgerPostingRules", IDUtils.toMap("year",
 6                         2011)));
 7     }
 8 
 

Which fails as year doesn’t match.

Summary

Above examples demonstrate how PlexRBAC API can be used along with instance or dynamic based security. In next post, I will describe caching and how PlexRBAC can be integrated with J2EE and Spring security.

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