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lua-casbin

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An authorization library that supports access control models like ACL, RBAC, ABAC in Lua (OpenResty)

Read the setup guide for OpenResty here.

News: Are you still worried about how to write the correct Casbin policy? Casbin online editor is coming to help! Try it at: http://casbin.org/editor/

casbin Logo

All the languages supported by Casbin:

golang java nodejs php
Casbin jCasbin node-Casbin PHP-Casbin
production-ready production-ready production-ready production-ready
python dotnet c++ rust
PyCasbin Casbin.NET Casbin-CPP Casbin-RS
production-ready production-ready beta-test production-ready

Installation

sudo luarocks install casbin

Get Started

  1. New Casbin enforcer with a model file and a policy file:
local Enforcer = require("casbin")
local e = Enforcer:new("path/to/model.conf", "path/to/policy.csv")

Note: you can also initialize an enforcer with policy in DB instead of file, see Policy-persistence section for details.

  1. Add an enforcement hook into your code right before the access happens:
local sub = "alice" -- the user that wants to access a resource.
local obj = "data1" -- the resource that is going to be accessed.
local act = "read" -- the operation that the user performs on the resource.

if e:enforce(sub, obj, act) then
    -- permit alice to read data1
else
    -- deny the request, show an error
end
  1. Besides the static policy file, Casbin also provides API for permission management at run-time. For example, You can get all the roles assigned to a user as below:
local roles = e:GetImplicitRolesForUser(sub)

See Policy management APIs for more usage.

Supported models

  1. ACL (Access Control List)
  2. ACL with superuser
  3. ACL without users: especially useful for systems that don't have authentication or user log-ins.
  4. ACL without resources: some scenarios may target for a type of resources instead of an individual resource by using permissions like write-article, read-log. It doesn't control the access to a specific article or log.
  5. RBAC (Role-Based Access Control)
  6. RBAC with resource roles: both users and resources can have roles (or groups) at the same time.
  7. RBAC with domains/tenants: users can have different role sets for different domains/tenants.
  8. ABAC (Attribute-Based Access Control): syntax sugar like resource.Owner can be used to get the attribute for a resource.
  9. RESTful: supports paths like /res/*, /res/:id and HTTP methods like GET, POST, PUT, DELETE.
  10. Deny-override: both allow and deny authorizations are supported, deny overrides the allow.
  11. Priority: the policy rules can be prioritized like firewall rules.

How it works?

In Casbin, an access control model is abstracted into a CONF file based on the PERM metamodel (Policy, Effect, Request, Matchers). So switching or upgrading the authorization mechanism for a project is just as simple as modifying a configuration. You can customize your own access control model by combining the available models. For example, you can get RBAC roles and ABAC attributes together inside one model and share one set of policy rules.

The most basic and simplest model in Casbin is ACL. ACL's model CONF is:

# Request definition
[request_definition]
r = sub, obj, act

# Policy definition
[policy_definition]
p = sub, obj, act

# Policy effect
[policy_effect]
e = some(where (p.eft == allow))

# Matchers
[matchers]
m = r.sub == p.sub && r.obj == p.obj && r.act == p.act

An example policy for ACL model is like:

p, alice, data1, read
p, bob, data2, write

It means:

  • alice can read data1
  • bob can write data2

Features

What Casbin does:

  1. enforce the policy in the classic {subject, object, action} form or a customized form as you defined, both allow and deny authorizations are supported.
  2. handle the storage of the access control model and its policy.
  3. manage the role-user mappings and role-role mappings (aka role hierarchy in RBAC).
  4. support built-in superuser like root or administrator. A superuser can do anything without explict permissions.
  5. multiple built-in operators to support the rule matching. For example, keyMatch can map a resource key /foo/bar to the pattern /foo*.

What Casbin does NOT do:

  1. authentication (aka verify username and password when a user logs in)
  2. manage the list of users or roles. I believe it's more convenient for the project itself to manage these entities. Users usually have their passwords, and Casbin is not designed as a password container. However, Casbin stores the user-role mapping for the RBAC scenario.

Documentation

https://casbin.org/docs/en/overview

Online editor

You can also use the online editor (https://casbin.org/editor/) to write your Casbin model and policy in your web browser. It provides functionality such as syntax highlighting and code completion, just like an IDE for a programming language.

Tutorials

https://casbin.org/docs/en/tutorials

Policy management

Casbin provides two sets of APIs to manage permissions:

  • Management API: the primitive API that provides full support for Casbin policy management.
  • RBAC API: a more friendly API for RBAC. This API is a subset of Management API. The RBAC users could use this API to simplify the code.

We also provide a web-based UI for model management and policy management:

model editor

policy editor

Policy persistence

https://casbin.org/docs/en/adapters

Policy consistence between multiple nodes

https://casbin.org/docs/en/watchers

Role manager

https://casbin.org/docs/en/role-managers

Examples

Model Model file Policy file
ACL basic_model.conf basic_policy.csv
ACL with superuser basic_model_with_root.conf basic_policy.csv
ACL without users basic_model_without_users.conf basic_policy_without_users.csv
ACL without resources basic_model_without_resources.conf basic_policy_without_resources.csv
RBAC rbac_model.conf rbac_policy.csv
RBAC with resource roles rbac_model_with_resource_roles.conf rbac_policy_with_resource_roles.csv
RBAC with domains/tenants rbac_model_with_domains.conf rbac_policy_with_domains.csv
ABAC abac_model.conf N/A
RESTful keymatch_model.conf keymatch_policy.csv
Deny-override rbac_model_with_deny.conf rbac_policy_with_deny.csv
Priority priority_model.conf priority_policy.csv

Middlewares

Authz middlewares for web frameworks: https://casbin.org/docs/en/middlewares

Our adopters

https://casbin.org/docs/en/adopters

How to Contribute

Please read the contributing guide.

Backers

Thank you to all our backers! 🙏 [Become a backer]

Sponsors

Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]

License

This project is licensed under the Apache 2.0 license.

Contact

If you have any issues or feature requests, please contact us. PR is welcomed.

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