Gatehouse

A flexible authorization library that combines role-based (RBAC), attribute-based (ABAC), and relationship-based (ReBAC) access control policies.

Features

• Multi-paradigm Authorization: Support for RBAC, ABAC, and ReBAC patterns
• Policy Composition: Combine policies with logical operators (AND, OR, NOT)
• Detailed Evaluation Tracing: Complete decision trace for debugging and auditing
• Fluent Builder API: Construct custom policies with a PolicyBuilder.
• Type Safety: Strongly typed resources/actions/contexts
• Async Ready: Built with async/await support

Core Components

Policy Trait

The foundation of the authorization system:

#[async_trait]
trait Policy<Subject, Resource, Action, Context> {
    async fn evaluate_access(
        &self,
        subject: &Subject,
        action: &Action,
        resource: &Resource,
        context: &Context,
    ) -> PolicyEvalResult;
}

PermissionChecker

Aggregates multiple policies (e.g. RBAC, ABAC) with OR logic by default: if any policy grants access, permission is granted.

let mut checker = PermissionChecker::new();
checker.add_policy(rbac_policy);
checker.add_policy(owner_policy);

// Check if access is granted
let result = checker.evaluate_access(&user, &action, &resource, &context).await;
if result.is_granted() {
    // Access allowed
} else {
    // Access denied
}

PolicyBuilder

The PolicyBuilder provides a fluent API to construct custom policies by chaining predicate functions for subjects, actions, resources, and context. Once built, the policy can be added to a PermissionChecker.

let custom_policy = PolicyBuilder::<MySubject, MyResource, MyAction, MyContext>::new("CustomPolicy")
    .subjects(|s| /* ... */)
    .actions(|a| /* ... */)
    .resources(|r| /* ... */)
    .context(|c| /* ... */)
    .when(|s, a, r, c| /* ... */)
    .build();

Built-in Policies

• RbacPolicy: Role-based access control
• AbacPolicy: Attribute-based access control
• RebacPolicy: Relationship-based access control

Combinators

AndPolicy: Grants access only if all inner policies allow access OrPolicy: Grants access if any inner policy allows access NotPolicy: Inverts the decision of an inner policy

Examples

See the examples directory for complete demonstration of:

• Role-based access control (rbac_policy)
• Relationship-based access control (rebac_policy)
• Policy combinators (combinator_policy)

Run with:

cargo run --example rbac_policy