Access Control Lists (ACLs) play a crucial role in cybersecurity and system management. This blog simplifies ACLs, explaining how they regulate who can access files, folders, and network resources. Discover how ACLs enforce security rules, manage user permissions, and ensure data remains safe and intact across different systems and environments.

This blog is quite long so I will separate it into many parts. The first part is about the overview of this concept and a must-have database. The second part will be the code implementation

What is ACL in Spring Security?

Spring Security ACL (Access Control List a.k.a Domain Object Security) is a module within the Spring Security framework that provides support for implementing access control at the domain object level in Spring applications. It extends beyond traditional role-based access control (RBAC) by allowing developers to define permissions for individual domain objects.

Key features of Spring Security ACL

Object-Level Security:

• ACL allows you to specify permissions (such as read, write, delete) for specific instances of domain objects. This means you can control access to individual objects based on the authenticated user’s identity or assigned roles.

Integration with Spring Security:

• It integrates with the core Spring Security framework, enabling developers to manage both authentication (who the user is) and authorization (what the user can do) in a unified manner.

Flexible Configuration:

• ACLs can be configured programmatically or through annotations, offering flexibility in how access control rules are defined and applied to domain objects.

Support for Different Data Stores:

• Spring Security ACL supports various data stores (relational databases like MySQL, PostgreSQL, and NoSQL databases like MongoDB), allowing you to persist ACL entries alongside your application’s domain model.

Fine-Grained Access Control:

• By leveraging ACL, developers can enforce fine-grained access control policies within their applications, ensuring that users have precise permissions to access specific instances of domain objects based on their roles and responsibilities.

ACL implementation with Spring Security

Of course we can do it ourselves. We can implement some functions to check permissions on domain object’s instances. However, when the data becomes larger, it’s really painful to do any queries on a million-record table. It may do a FULL SCAN TABLE query by using WHERE, GROUP, etc. in the database and lock the table. Therefore, that’s not what we expect.

Let’s explore the concept of implementation in Spring Security

ACLs in Spring Security enable fine-grained access control by associating permissions (READ, WRITE, etc.) with domain objects (Product, Document, etc.) for different users or roles. This is achieved through:

• Domain Objects: These are the objects in your application that you want to protect with ACL-based security. For example, Product, Document, Customer, etc.
• ACL Entries: These entries define permissions (READ, WRITE, etc.) granted to specific principals (users or roles) on specific domain objects. We can also customize base permissions to solve the specific business.
• Security Identities (SIDs): These represent the principles to which ACL entries apply. SIDs can be either users (PrincipalSid) or roles (GrantedAuthoritySid).
• ACL Services: Services responsible for managing ACL entries, including creation, retrieval, update, and deletion.

Database Tables for ACL

acl_object_identity: This table stores information about secured domain objects (entities) that are protected by ACLs. Each row typically represents a specific instance of a domain object that is secured.

• Columns may include id (primary key), object_id_class (the type of the secured object), object_id_identity (the identifier of the secured object instance), and other metadata related to ACLs.

acl_entry: This table defines the permissions (ACEs – Access Control Entries) granted for each ACL (Access Control List) on a specific domain object instance.

• Columns often include id (primary key), acl_object_identity (foreign key referencing acl_object_identity.id), ace_order (order of ACEs), sid (security identifier, representing a user or group), mask (bitmask indicating permissions), granting (whether permission is granted or revoked), and other fields related to ACL entries.

acl_sid: This table stores security identities (sids), which can represent either users or granted authorities (roles).

• Columns typically include id (primary key), principal (boolean indicating whether it represents a user or a role), sid (the identifier of the user or role).

acl_class: This table defines the types of domain objects that can be secured by ACLs.

• Columns usually include id (primary key), class (the fully qualified class name of the domain object), and possibly other metadata related to supported object types.

The code implementation will be updated in the next blog.

Thank you for reading.