Crate cedar_policy

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§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(Some(alice), Some(action), Some(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(Some(bob), Some(action), Some(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

See CHANGELOG

§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§

  • entities
    Extended functionality for Entities struct
  • extensions
    This module contains all of the standard Cedar extensions.
  • ffi
    Functions for interacting with cedar_policy, intended to be easier to use in an FFI context than the root-level cedar_policy interface
  • frontendDeprecated
    Frontend utilities, see comments in the module itself

Structs§

  • Authorizer
    Authorizer object, which provides responses to authorization queries
  • 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
  • EntityId
    Identifier portion of the EntityUid type.
  • 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".
  • EvaluationError
    An error generated while evaluating an expression
  • Expression
    Expressions to be evaluated
  • ParseErrors
    Multiple parse errors.
  • PartialResponsepartial-eval
    A partially evaluated authorization response. Splits the results into several categories: satisfied, false, and residual for each policy effect. Also tracks all the errors that were encountered during evaluation.
  • Policy
    Structure for a Policy. Includes both static policies and template-linked policies.
  • 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
  • Response
    Authorization response returned from the Authorizer
  • RestrictedExpression
    “Restricted” expressions are used for attribute values and context.
  • 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
  • SourceLocation
    Represents a location in Cedar policy source.
  • Template
    Policy template datatype
  • UnsetSchemapartial-eval
    A marker type that indicates Schema is not set for a request
  • ValidationError
    An error generated by the validator when it finds a potential problem in a policy. The error contains a enumeration that specifies the kind of problem, and provides details specific to that kind of problem. The error also records where the problem was encountered.
  • ValidationResult
    Contains the result of policy validation. The result includes the list of issues found by validation and whether validation succeeds or fails. Validation succeeds if there are no fatal errors. There may still be non-fatal warnings present when validation passes.
  • ValidationWarning
    Warnings found in Cedar policies
  • Validator
    Validator object, which provides policy validation and typechecking.

Enums§

Functions§

  • confusable_string_checker
    Scan a set of policies for potentially confusing/obfuscating text. These checks are also provided through Validator::validate which provides more comprehensive error detection, but this function can be used to check for confusable strings without defining a schema.
  • eval_expression
    Evaluates an expression. If evaluation results in an error (e.g., attempting to access a non-existent Entity or Record, passing the wrong number of arguments to a function etc.), that error is returned as a String