permissions

Permissions are rules that determine what actions a user or process may perform on a system resource. They are the practical enforcement of access control, restricting or enabling operations such as reading, writing, executing, or administering an object or service. Proper permissions help protect privacy, data integrity, and system stability.

Common models of permission management include discretionary access control (DAC), mandatory access control (MAC), role-based access control (RBAC), and attribute-based access control (ABAC). DAC allows resource owners to grant access to others. MAC enforces system-wide policies that users cannot override. RBAC assigns permissions to roles, and users gain those permissions by assuming appropriate roles. ABAC uses attributes of users, resources, and context to make decisions.

Implementations vary by domain. Operating systems use file permissions and access control lists to regulate access to files and devices; Unix-like systems often specify owner, group, and others with read, write, and execute rights. Databases use GRANT and REVOKE statements to control data access and operations. In cloud environments, identity and access management (IAM) policies define who can perform actions on resources. Across domains, the principle of least privilege aims to grant only the minimum permissions needed to perform a task, while need-to-know and separation of duties reduce risk of abuse.

Management tasks include provisioning, modification, revocation, and auditing of permissions. Misconfigurations, privilege creep, and overly broad access are common risks. Understanding the policy, mechanisms, and ongoing governance of permissions is essential for secure and compliant systems.