pycasbin

by casbin

casbin / pycasbin

An authorization library that supports access control models like ACL, RBAC, ABAC in Python

529 Stars 74 Forks Last release: 9 months ago (v0.8.4) Apache License 2.0 102 Commits 13 Releases

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PyCasbin

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News: still worry about how to write the correct Casbin policy?

Casbin online editor
is coming to help! Try it at: http://casbin.org/editor/

Casbin is a powerful and efficient open-source access control library for Python projects. It provides support for enforcing authorization based on various access control models.

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

Table of contents

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

We also support multi-line mode by appending '\' in the end:

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

Further more, if you are using ABAC, you can try operator

in
like following in Casbin golang edition (jCasbin and Node-Casbin are not supported yet):
# Matchers
[matchers]
m = r.obj == p.obj && r.act == p.act || r.obj in ('data2', 'data3')

But you SHOULD make sure that the length of the array is MORE than 1, otherwise there will cause it to panic.

For more operators, you may take a look at govaluate

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.

Installation

pip install casbin

Documentation

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

Online editor

You can also use the online editor (http://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

Get started

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

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

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

if e.enforce(sub, obj, act): # permit alice to read data1 pass else: # deny the request, show an error pass

  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:
roles = e.get_roles("alice")

See Policy management APIs for more usage.

  1. Please refer to the
    tests
    files for more usage.

Policy management

Casbin provides two sets of APIs to manage permissions:

  • Management API: the primitive API that provides full support for Casbin policy management. See here for examples.
  • 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. See here for examples.

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

Role manager

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

Benchmarks

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

Examples

Model

Model file Policy file
ACL basic_model.conf basic_policy.csv
ACL with superuser basicmodelwith_root.conf basic_policy.csv
ACL without users basicmodelwithout_users.conf basicpolicywithout_users.csv
ACL without resources basicmodelwithout_resources.conf basicpolicywithout_resources.csv
RBAC rbac_model.conf rbac_policy.csv
RBAC with resource roles rbacmodelwithresourceroles.conf rbacpolicywithresourceroles.csv
RBAC with domains/tenants rbacmodelwith_domains.conf rbacpolicywith_domains.csv
ABAC abac_model.conf N/A
RESTful keymatch_model.conf keymatch_policy.csv
Deny-override rbacmodelwith_deny.conf rbacpolicywith_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

Contributors

This project exists thanks to all the people who contribute.

Backers

Thank you to all our backers! ๐Ÿ™ [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. - https://github.com/casbin/pycasbin/issues - [email protected] - Tencent QQ group: 546057381

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