lua-casbin

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/

All the languages supported by Casbin:


Casbin	jCasbin	node-Casbin	PHP-Casbin
production-ready	production-ready	production-ready	production-ready


PyCasbin	Casbin.NET	Casbin-CPP	Casbin-RS
production-ready	production-ready	beta-test	production-ready

Installation

sudo luarocks install casbin

Get Started

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.

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

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

ACL (Access Control List)
ACL with superuser
ACL without users: especially useful for systems that don't have authentication or user log-ins.
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.
RBAC (Role-Based Access Control)
RBAC with resource roles: both users and resources can have roles (or groups) at the same time.
RBAC with domains/tenants: users can have different role sets for different domains/tenants.
ABAC (Attribute-Based Access Control): syntax sugar like resource.Owner can be used to get the attribute for a resource.
RESTful: supports paths like /res/*, /res/:id and HTTP methods like GET, POST, PUT, DELETE.
Deny-override: both allow and deny authorizations are supported, deny overrides the allow.
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:

enforce the policy in the classic {subject, object, action} form or a customized form as you defined, both allow and deny authorizations are supported.
handle the storage of the access control model and its policy.
manage the role-user mappings and role-role mappings (aka role hierarchy in RBAC).
support built-in superuser like root or administrator. A superuser can do anything without explict permissions.
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:

authentication (aka verify username and password when a user logs in)
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:

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