Crate cedar_policy

Source
Expand description

§Cedar-Policy

Cedar Logo

Cedar is a language for defining permissions as policies, which describe who should have access to what. It is also a specification for evaluating those policies. Use Cedar policies to control what each user of your application is permitted to do and what resources they may access.

§Using Cedar

Cedar can be used in your application by depending on the cedar-policy crate.

Just add cedar-policy as a dependency by running

cargo add cedar-policy

§Quick Start

Let’s write a super simple Cedar policy and test it:

permit(principal == User::"alice", action == Action::"view", resource == File::"93");

This policy permits exactly one authorization request, alice is allowed to view file 93. Any other authorization request will be implicitly denied. Let’s embed this policy in Rust and use the Cedar Authorizer:

use cedar_policy::*;

fn main() {
    const POLICY_SRC: &str = r#"
permit(principal == User::"alice", action == Action::"view", resource == File::"93");
"#;
    let policy: PolicySet = POLICY_SRC.parse().unwrap();

    let action = r#"Action::"view""#.parse().unwrap();
    let alice = r#"User::"alice""#.parse().unwrap();
    let file = r#"File::"93""#.parse().unwrap();
    let request = Request::new(alice, action, file, Context::empty(), None).unwrap();

    let entities = Entities::empty();
    let authorizer = Authorizer::new();
    let answer = authorizer.is_authorized(&request, &policy, &entities);

    // Should output `Allow`
    println!("{:?}", answer.decision());

    let action = r#"Action::"view""#.parse().unwrap();
    let bob = r#"User::"bob""#.parse().unwrap();
    let file = r#"File::"93""#.parse().unwrap();
    let request = Request::new(bob, action, file, Context::empty(), None).unwrap();

    let answer = authorizer.is_authorized(&request, &policy, &entities);

    // Should output `Deny`
    println!("{:?}", answer.decision());
}

If you’d like to see more details on what can be expressed as Cedar policies, see the documentation.

Examples of how to use Cedar in an application are contained in the repository cedar-examples. The most full-featured of these is TinyTodo, which is a simple task list management service whose users’ requests, sent as HTTP messages, are authorized by Cedar.

§Documentation

General documentation for Cedar is available at docs.cedarpolicy.com, with source code in the cedar-policy/cedar-docs repository.

Generated documentation for the latest version of the Rust crates can be accessed on docs.rs.

If you’re looking to integrate Cedar into a production system, please be sure the read the security best practices

§Building

To build, simply run cargo build (or cargo build --release).

§What’s New

Changelogs for all release branches and the main branch of this repository are all maintained on the main branch; the most up-to-date changelog for this crate is here.

For a list of the current and past releases, see crates.io or Releases.

§Security

See SECURITY

§Contributing

We welcome contributions from the community. Please either file an issue, or see CONTRIBUTING

§License

This project is licensed under the Apache-2.0 License.

Modules§

Structs§

  • AccessTrieentity-manifest
    A Trie representing a set of data paths to load, starting implicitly from a Cedar value.
  • Authorizer
    Authorizer object, which provides responses to authorization queries
  • ConcretizationError
    Errors that occur during concretizing a partial request
  • ContainsUnknown
    The PartialValue is a residual, i.e., contains an unknown
  • Context
    the Context object for an authorization request
  • Diagnostics
    Diagnostics providing more information on how a Decision was reached
  • Entities
    Represents an entity hierarchy, and allows looking up Entity objects by Uid.
  • Entity
    Entity datatype
  • EntityAttrEvaluationError
    Error when evaluating an entity attribute or tag
  • EntityId
    Identifier portion of the EntityUid type.
  • EntityManifestentity-manifest
    Data structure storing what data is needed based on the the RequestType. For each request type, the EntityManifest stores a RootAccessTrie of data to retrieve.
  • EntityNamespace
    Represents a namespace.
  • EntityTypeName
    Represents an entity type name. Consists of a namespace and the type name.
  • EntityUid
    Unique id for an entity, such as User::"alice".
  • Expression
    Expressions to be evaluated
  • ParseError
    Errors that can occur when parsing policies or expressions. Marked as non_exhaustive to support adding additional error information in the future without a major version bump.
  • ParseErrors
    Represents one or more ParseErrors encountered when parsing a policy or expression.
  • PartialResponsepartial-eval
    A partially evaluated authorization response.
  • Policy
    Structure for a Policy. Includes both static policies and template-linked policies.
  • PolicyFromJsonError
    Error when converting a policy or template from JSON format
  • PolicyId
    Unique ids assigned to policies and templates.
  • PolicySet
    Represents a set of Policys
  • Record
    A record of Cedar values
  • Request
    An authorization request is a tuple <P, A, R, C> where
  • RequestBuilderpartial-eval
    Builder for a Request
  • RequestEnv
    The “type” of a Request, i.e., the EntityTypeNames of principal and resource, and the EntityUid of action
  • Response
    Authorization response returned from the Authorizer
  • RestrictedExpression
    “Restricted” expressions are used for attribute values and context.
  • RootAccessTrieentity-manifest
    A RootAccessTrie is a trie describing a set of data paths to retrieve. Each edge in the trie is either a record or entity dereference.
  • Schema
    Object containing schema information used by the validator.
  • SchemaFragment
    Contains all the type information used to construct a Schema that can be used to validate a policy.
  • Set
    Sets of Cedar values
  • SlotId
    Identifier for a Template slot
  • Template
    Policy template datatype
  • UnsetSchemapartial-eval
    A marker type that indicates Schema is not set for a request
  • ValidationResult
    Contains the result of policy validation.
  • Validator
    Validator object, which provides policy validation and typechecking.

Enums§

Functions§

Type Aliases§

  • Fieldsentity-manifest
    A map of data fields to AccessTries. The keys to this map form the edges in the access trie, pointing to sub-tries.