casbin

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README

Casbin

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Note: The plugins and middleware based on Casbin can be found at: https://github.com/casbin

casbin Logo

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

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.

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.

Installation

go get github.com/casbin/casbin

Get started

  1. New a Casbin enforcer with a model file and a policy file:
e := casbin.NewEnforcer("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) == true {
    // permit alice to read data1
} else {
    // deny the request, show an error
}
  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.GetRoles("alice")

Note: we provide 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.
  1. Please refer to the _test.go files for more usage.

Syntax for models

See: Model.md

Persistence

In Casbin, the policy storage is implemented as an adapter (aka middleware for Casbin). To keep light-weight, we don't put adapter code in the main library. A complete list of Casbin adapters is provided as below. Any 3rd-party contribution on a new adapter is welcomed, please inform us and I will put it in this list:)

Adapter Type Author Description
File Adapter (built-in) File Casbin Persistence for .CSV (Comma-Separated Values) files
MySQL Adapter RDBMS Casbin Persistence for MySQL
Cassandra Adapter NoSQL Casbin Persistence for Apache Cassandra DB
Consul Adapter KV store @ankitm123 Persistence for HashiCorp Consul
Redis Adapter KV store @ankitm123 Persistence for Redis
Protobuf Adapter Stream Casbin Persistence for Google Protocol Buffers
Xorm Adapter ORM Casbin MySQL, PostgreSQL, TiDB, SQLite, SQL Server, Oracle are supported by Xorm

All adapters should implement the Adapter interface by providing two methods:LoadPolicy(model model.Model) error and SavePolicy(model model.Model) error. And as a convention, the adapter should be able to automatically create a database named casbin if it doesn't exist and use it for policy storage.

Note: Unlike the policy, the model can be loaded from a CONF file only. Because we think the model is not a frequently modified part at run-time, so we don't implement an API to save the model into a file or database.

File adapter

Below shows how to initialize an enforcer from the built-in file adapter:

e := casbin.NewEnforcer("examples/basic_model.conf", "examples/basic_policy.csv")

This is the same with:

a := persist.NewFileAdapter("examples/basic_policy.csv")
e := casbin.NewEnforcer("examples/basic_model.conf", a)
MySQL adapter

Below shows how to initialize an enforcer from MySQL database. it connects to a MySQL DB on 127.0.0.1:3306 with root and blank password.

a := mysqladapter.NewDBAdapter("mysql", "root:@tcp(127.0.0.1:3306)/")
e := casbin.NewEnforcer("examples/basic_model.conf", a)
Use your own storage adapter

You can use your own adapter like below:

a := yourpackage.YourNewAdapter(your_params)
e := casbin.NewEnforcer("examples/basic_model.conf", a)
Load/Save at run-time

You may also want to reload the model, reload the policy or save the policy after initialization:

// Reload the model from the model CONF file.
e.LoadModel()

// Reload the policy from file/database.
e.LoadPolicy()

// Save the current policy (usually after changed with Casbin API) back to file/database.
e.SavePolicy()

What if I don't want to reply on files (.conf, .csv)?

The policy rules can be loaded and saved with various adapters, so it doesn't rely on .CSV files necessarily. The model can be initialized from code instead of using .CONF file. Here's an example for the RBAC model:

// Initialize the model from Go code.
m := casbin.NewModel()
m.AddDef("r", "r", "sub, obj, act")
m.AddDef("p", "p", "sub, obj, act")
m.AddDef("g", "g", "_, _")
m.AddDef("e", "e", "some(where (p.eft == allow))")
m.AddDef("m", "m", "g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act")

// Load the policy rules from the .CSV file adapter.
// Replace it with your adapter to avoid files.
a := persist.NewFileAdapter("examples/rbac_policy.csv")

// Create the enforcer.
e := casbin.NewEnforcer(m, a)

Or you can just get the model from one single string:

// Initialize the model from a string.
text :=
`
[request_definition]
r = sub, obj, act

[policy_definition]
p = sub, obj, act

[role_definition]
g = _, _

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

[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act
`
m := NewModel(text)

// Load the policy rules from the .CSV file adapter.
// Replace it with your adapter to avoid files.
a := persist.NewFileAdapter("examples/rbac_policy.csv")

// Create the enforcer.
e := casbin.NewEnforcer(m, a)

These two ways are equivalent with the common usage:

examples/rbac_model.conf:

[request_definition]
r = sub, obj, act

[policy_definition]
p = sub, obj, act

[role_definition]
g = _, _

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

[matchers]
m = g(r.sub, p.sub) && r.obj == p.obj && r.act == p.act

e := casbin.NewEnforcer("examples/rbac_model.conf", "examples/rbac_policy.csv")

Error handling

Error or panic may happen when you use Casbin for reasons like:

  1. Invalid syntax in model file (.conf).
  2. Invalid syntax in policy file (.csv).
  3. Custom error from storage adapters, e.g., MySQL fails to connect.
  4. Casbin's bug.

There are five main functions you may need to care about for error or panic:

Function Behavior on error What if I want error instead of panic?
NewEnforcer() Cause panic Please use NewEnforcerSafe()
LoadModel() Cause panic Please use LoadModelSafe()
LoadPolicy() Return error N/A
SavePolicy() Return error N/A
Enforce() Cause panic Please use EnforceSafe()

Note: NewEnforcer() calls LoadModel() and LoadPolicy() inside. So you don't have to call the latter two calls when using NewEnforcer().

Why not just return error for all the functions?

The author believes that Golang error is very unfriendly for developers to debug, because it's only a string and has no faulty call stack information. The panic can show call stack and integrate well with Golang IDEs. Most of the Casbin users are developers too. And they usually don't write the Casbin model or policy correctly at the first time (which causes error or panic). So they can benefit from the advantages of panic. However, there are still many people who favor error more than panic. So we provide the xxxSafe() functions which just wrap the xxx() functions by translating panic into error. You can just use xxx() or xxxSafe() functions based on personal tastes.

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

Our adopters

Web frameworks
  • Beego: An open-source, high-performance web framework for Go, via built-in plugin: plugins/authz
  • Caddy: Fast, cross-platform HTTP/2 web server with automatic HTTPS, via plugin: caddy-authz
  • Gin: A HTTP web framework featuring a Martini-like API with much better performance, via plugin: authz
  • Revel: A high productivity, full-stack web framework for the Go language, via plugin: revel-authz
  • Echo: High performance, minimalist Go web framework, via plugin: echo-authz (thanks to @xqbumu)
  • Iris: The fastest web framework for Go in (THIS) Earth. HTTP/2 Ready-To-GO, via plugin: casbin (thanks to @hiveminded)
  • Negroni: Idiomatic HTTP Middleware for Golang, via plugin: negroni-authz
  • Tango: Micro & pluggable web framework for Go, via plugin: authz
  • Chi: A lightweight, idiomatic and composable router for building HTTP services, via plugin: chi-authz
  • Macaron: A high productive and modular web framework in Go, via plugin: authz
  • DotWeb: Simple and easy go web micro framework, via plugin: authz
Others

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.

Documentation

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func NewModel added in v0.8.0 

func NewModel(params ...interface{}) model.Model

NewModel creates a model.

Types

type Effect added in v0.2.0 

type Effect int

Effect is the result for a policy rule. 

const (
	EFFECT_ALLOW Effect = iota
	EFFECT_INDETERMINATE
	EFFECT_DENY
)

type Enforcer 

type Enforcer struct {
	// contains filtered or unexported fields
}

Enforcer is the main interface for authorization enforcement and policy management.

func NewEnforcer added in v0.0.5 

func NewEnforcer(params ...interface{}) *Enforcer

NewEnforcer creates an enforcer via file or DB. File: e := casbin.NewEnforcer("path/to/basic_model.conf", "path/to/basic_policy.conf") MySQL DB: a := mysqladapter.NewDBAdapter("mysql", "mysql_username:mysql_password@tcp(127.0.0.1:3306)/") e := casbin.NewEnforcer("path/to/basic_model.conf", a)

func NewEnforcerSafe added in v0.3.0 

func NewEnforcerSafe(params ...interface{}) (e *Enforcer, err error)

NewEnforcerSafe calls NewEnforcer in a safe way, returns error instead of causing panic.

func (*Enforcer) AddFunction added in v0.0.6 

func (e *Enforcer) AddFunction(name string, function func(args ...interface{}) (interface{}, error))

AddFunction adds a customized function.

func (*Enforcer) AddGroupingPolicy added in v0.0.2 

func (e *Enforcer) AddGroupingPolicy(params ...interface{}) bool

AddGroupingPolicy adds a role inheritance rule to the current policy. If you try to add an existing policy, the call fails and returns false.

func (*Enforcer) AddPermissionForUser added in v0.0.5 

func (e *Enforcer) AddPermissionForUser(user string, permission ...string) bool

AddPermissionForUser adds a permission for a user or role. Returns false if the user or role already has the permission.

func (*Enforcer) AddPolicy added in v0.0.2 

func (e *Enforcer) AddPolicy(params ...interface{}) bool

AddPolicy adds an authorization rule to the current policy. If you try to add an existing policy, the call fails and returns false.

func (*Enforcer) AddRoleForUser added in v0.0.5 

func (e *Enforcer) AddRoleForUser(user string, role string) bool

AddRoleForUser adds a role for a user. Returns false if the user already has the role.

func (*Enforcer) ClearPolicy added in v0.0.5 

func (e *Enforcer) ClearPolicy()

ClearPolicy clears all policy.

func (*Enforcer) DeletePermission added in v0.0.5 

func (e *Enforcer) DeletePermission(permission ...string)

DeletePermission deletes a permission.

func (*Enforcer) DeletePermissionForUser added in v0.6.0 

func (e *Enforcer) DeletePermissionForUser(user string, permission ...string)

DeletePermissionForUser deletes a permission for a user or role.

func (*Enforcer) DeletePermissionsForUser added in v0.0.5 

func (e *Enforcer) DeletePermissionsForUser(user string)

DeletePermissionsForUser deletes permissions for a user or role.

func (*Enforcer) DeleteRole added in v0.0.5 

func (e *Enforcer) DeleteRole(role string)

DeleteRole deletes a role.

func (*Enforcer) DeleteRoleForUser added in v0.6.0 

func (e *Enforcer) DeleteRoleForUser(user string, role string)

DeleteRoleForUser deletes a role for a user.

func (*Enforcer) DeleteRolesForUser added in v0.0.5 

func (e *Enforcer) DeleteRolesForUser(user string)

DeleteRolesForUser deletes all roles for a user.

func (*Enforcer) DeleteUser added in v0.0.5 

func (e *Enforcer) DeleteUser(user string)

DeleteUser deletes a user.

func (*Enforcer) Enable added in v0.0.2 

func (e *Enforcer) Enable(enable bool)

Enable changes the enforcing state of Casbin, when Casbin is disabled, all access will be allowed by the Enforce() function.

func (*Enforcer) EnableLog added in v0.6.0 

func (e *Enforcer) EnableLog(enable bool)

EnableLog changes whether to print Casbin log to the standard output.

func (*Enforcer) Enforce added in v0.0.2 

func (e *Enforcer) Enforce(rvals ...interface{}) bool

Enforce decides whether a "subject" can access a "object" with the operation "action", input parameters are usually: (sub, obj, act).

func (*Enforcer) EnforceSafe added in v0.3.0 

func (e *Enforcer) EnforceSafe(rvals ...interface{}) (result bool, err error)

EnforceSafe calls Enforce in a safe way, returns error instead of causing panic.

func (*Enforcer) GetAdapter added in v0.8.0 

func (e *Enforcer) GetAdapter() persist.Adapter

GetAdapter gets the current adapter.

func (*Enforcer) GetAllActions added in v0.0.2 

func (e *Enforcer) GetAllActions() []string

GetAllActions gets the list of actions that show up in the current policy.

func (*Enforcer) GetAllObjects added in v0.0.2 

func (e *Enforcer) GetAllObjects() []string

GetAllObjects gets the list of objects that show up in the current policy.

func (*Enforcer) GetAllRoles added in v0.0.2 

func (e *Enforcer) GetAllRoles() []string

GetAllRoles gets the list of roles that show up in the current policy.

func (*Enforcer) GetAllSubjects added in v0.0.2 

func (e *Enforcer) GetAllSubjects() []string

GetAllSubjects gets the list of subjects that show up in the current policy.

func (*Enforcer) GetFilteredGroupingPolicy added in v0.9.0 

func (e *Enforcer) GetFilteredGroupingPolicy(fieldIndex int, fieldValues ...string) [][]string

GetFilteredGroupingPolicy gets all the role inheritance rules in the policy, field filters can be specified.

func (*Enforcer) GetFilteredPolicy added in v0.0.2 

func (e *Enforcer) GetFilteredPolicy(fieldIndex int, fieldValues ...string) [][]string

GetFilteredPolicy gets all the authorization rules in the policy, field filters can be specified.

func (*Enforcer) GetGroupingPolicy added in v0.0.2 

func (e *Enforcer) GetGroupingPolicy() [][]string

GetGroupingPolicy gets all the role inheritance rules in the policy.

func (*Enforcer) GetModel added in v0.0.5 

func (e *Enforcer) GetModel() model.Model

GetModel gets the current model.

func (*Enforcer) GetPermissionsForUser added in v0.0.5 

func (e *Enforcer) GetPermissionsForUser(user string) [][]string

GetPermissionsForUser gets permissions for a user or role.

func (*Enforcer) GetPolicy added in v0.0.2 

func (e *Enforcer) GetPolicy() [][]string

GetPolicy gets all the authorization rules in the policy.

func (*Enforcer) GetRolesForUser added in v0.0.5 

func (e *Enforcer) GetRolesForUser(name string) []string

GetRolesForUser gets the roles that a user has.

func (*Enforcer) GetUsersForRole added in v0.7.0 

func (e *Enforcer) GetUsersForRole(name string) []string

GetUsersForRole gets the users that has a role.

func (*Enforcer) HasGroupingPolicy added in v0.6.0 

func (e *Enforcer) HasGroupingPolicy(params ...interface{}) bool

HasGroupingPolicy determines whether a role inheritance rule exists.

func (*Enforcer) HasPermissionForUser added in v0.6.0 

func (e *Enforcer) HasPermissionForUser(user string, permission ...string) bool

HasPermissionForUser determines whether a user has a permission.

func (*Enforcer) HasPolicy added in v0.6.0 

func (e *Enforcer) HasPolicy(params ...interface{}) bool

HasPolicy determines whether an authorization rule exists.

func (*Enforcer) HasRoleForUser added in v0.6.0 

func (e *Enforcer) HasRoleForUser(name string, role string) bool

HasRoleForUser determines whether a user has a role.

func (*Enforcer) InitWithAdapter added in v0.0.5 

func (e *Enforcer) InitWithAdapter(modelPath string, adapter persist.Adapter)

InitWithAdapter initializes an enforcer with a database adapter.

func (*Enforcer) InitWithFile added in v0.0.5 

func (e *Enforcer) InitWithFile(modelPath string, policyPath string)

InitWithFile initializes an enforcer with a model file and a policy file.

func (*Enforcer) InitWithModelAndAdapter added in v0.8.0 

func (e *Enforcer) InitWithModelAndAdapter(m model.Model, adapter persist.Adapter)

InitWithModelAndAdapter initializes an enforcer with a model and a database adapter.

func (*Enforcer) LoadModel added in v0.0.5 

func (e *Enforcer) LoadModel()

LoadModel reloads the model from the model CONF file. Because the policy is attached to a model, so the policy is invalidated and needs to be reloaded by calling LoadPolicy().

func (*Enforcer) LoadModelSafe added in v0.3.0 

func (e *Enforcer) LoadModelSafe() (err error)

LoadModelSafe calls LoadModel in a safe way, returns error instead of causing panic.

func (*Enforcer) LoadPolicy added in v0.0.2 

func (e *Enforcer) LoadPolicy() error

LoadPolicy reloads the policy from file/database.

func (*Enforcer) RemoveFilteredGroupingPolicy added in v0.0.5 

func (e *Enforcer) RemoveFilteredGroupingPolicy(fieldIndex int, fieldValues ...string)

RemoveFilteredGroupingPolicy removes a role inheritance rule from the current policy, field filters can be specified.

func (*Enforcer) RemoveFilteredPolicy added in v0.0.5 

func (e *Enforcer) RemoveFilteredPolicy(fieldIndex int, fieldValues ...string)

RemoveFilteredPolicy removes an authorization rule from the current policy, field filters can be specified.

func (*Enforcer) RemoveGroupingPolicy added in v0.0.2 

func (e *Enforcer) RemoveGroupingPolicy(params ...interface{})

RemoveGroupingPolicy removes a role inheritance rule from the current policy.

func (*Enforcer) RemovePolicy added in v0.0.2 

func (e *Enforcer) RemovePolicy(params ...interface{})

RemovePolicy removes an authorization rule from the current policy.

func (*Enforcer) SavePolicy added in v0.0.2 

func (e *Enforcer) SavePolicy() error

SavePolicy saves the current policy (usually after changed with Casbin API) back to file/database.

func (*Enforcer) SetAdapter added in v0.8.0 

func (e *Enforcer) SetAdapter(adapter persist.Adapter)

SetAdapter sets the current adapter.

func (*Enforcer) SetModel added in v0.7.0 

func (e *Enforcer) SetModel(model model.Model)

SetModel sets the current model.

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