acl

An Access Control List module, based on Redis with Express middleware support

npm install acl
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NODE ACL - Access Control Lists for Node

This module provides a minimalistic ACL implementation inspired by Zend_ACL.

When you develop a web site or application you will soon notice that sessions are not enough to protect all the available resources. Avoiding that malicious users access other users content proves a much more complicated task than anticipated. ACL can solve this problem in a flexible and elegant way.

Create roles and assign roles to users. Sometimes it may even be useful to create one role per user, to get the finest granularity possible, while in other situations you will give the asterisk permission for admin kind of functionality.

A Redis, MongoDB and In-Memory based backends are provided, but the generic backend interface can be implemented for supporting other databases.

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Status

BuildStatus

Features

  • Users
  • Roles
  • Hierarchies
  • Resources
  • Express middleware for protecting resources.
  • Robust implementation with good unit test coverage.

Installation

Using npm:

npm install acl

Documentation

Examples

Create your acl module by requiring it and instantiating it with a valid backend instance:

var acl = require('acl');

// Using redis backend
acl = new acl(new acl.redisBackend(redisClient, prefix));

// Or Using the memory backend
acl = new acl(new acl.memoryBackend());

// Or Using the mongodb backend
acl = new acl(new acl.mongodbBackend(dbInstance, prefix));

All the following functions return a promise or optionally take a callback with an err parameter as last parameter. We omit them in the examples for simplicity.

Create roles implicitly by giving them permissions:

// guest is allowed to view blogs
acl.allow('guest', 'blogs', 'view')

// allow function accepts arrays as any parameter
acl.allow('member', 'blogs', ['edit','view', 'delete'])

Users are likewise created implicitly by assigning them roles:

acl.addUserRoles('joed', 'guest')

Hierarchies of roles can be created by assigning parents to roles:

acl.addRoleParents('baz', ['foo','bar'])

Note that the order in which you call all the functions is irrelevant (you can add parents first and assign permissions to roles later)

acl.allow('foo', ['blogs','forums','news'], ['view', 'delete'])

Use the wildcard to give all permissions:

acl.allow('admin', ['blogs','forums'], '*')

Sometimes is necessary to set permissions on many different roles and resources. This would lead to unnecessary nested callbacks for handling errors. Instead use the following:

acl.allow([
    {
        roles:['guest','member'], 
        allows:[
            {resources:'blogs', permissions:'get'},
            {resources:['forums','news'], permissions:['get','put','delete']}
        ]
    },
    {
        roles:['gold','silver'], 
        allows:[
            {resources:'cash', permissions:['sell','exchange']},
            {resources:['account','deposit'], permissions:['put','delete']}
        ]
    }
])

You can check if a user has permissions to access a given resource with isAllowed:

acl.isAllowed('joed', 'blogs', 'view', function(err, res){
    if(res){
        console.log("User joed is allowed to view blogs")
    }
}

Of course arrays are also accepted in this function:

acl.isAllowed('jsmith', 'blogs', ['edit','view','delete'])

Note that all permissions must be full filed in order to get true.

Sometimes is necessary to know what permissions a given user has over certain resources:

acl.allowedPermissions('james', ['blogs','forums'], function(err, permissions){
    console.log(permissions)
})

It will return an array of resource:[permissions] like this:

[{'blogs' : ['get','delete']},
 {'forums':['get','put']}]

Finally, we provide a middleware for Express for easy protection of resources.

acl.middleware()

We can protect a resource like this:

app.put('/blogs/:id', acl.middleware(), function(req, res, next){…}

The middleware will protect the resource named by req.url, pick the user from req.session.userId and check the permission for req.method, so the above would be equivalent to something like this:

acl.isAllowed(req.session.userId, '/blogs/12345', 'put')

The middleware accepts 3 optional arguments, that are useful in some situations. For example, sometimes we cannot consider the whole url as the resource:

app.put('/blogs/:id/comments/:commentId', acl.middleware(3), function(req, res, next){…}

In this case the resource will be just the three first components of the url (without the ending slash).

It is also possible to add a custom userId or check for other permissions than the method:

app.put('/blogs/:id/comments/:commentId', acl.middleware(3, 'joed', 'post'), function(req, res, next){…}

Methods

addUserRoles( userId, roles, function(err) )

Adds roles to a given user id.

Arguments

    userId   {String|Number} User id.
    roles    {String|Array} Role(s) to add to the user id.
    callback {Function} Callback called when finished.

removeUserRoles( userId, roles, function(err) )

Remove roles from a given user.

Arguments

    userId   {String|Number} User id.
    roles    {String|Array} Role(s) to remove to the user id.
    callback {Function} Callback called when finished.

userRoles( userId, function(err, roles) )

Return all the roles from a given user.

Arguments

    userId   {String|Number} User id.
    callback {Function} Callback called when finished.

addRoleParents( role, parents, function(err) )

Adds a parent or parent list to role.

Arguments

    role     {String} User id.
    parents  {String|Array} Role(s) to remove to the user id.
    callback {Function} Callback called when finished.

removeRole( role, function(err) )

Removes a role from the system.

Arguments

    role     {String} Role to be removed
    callback {Function} Callback called when finished.

removeResource( resource, function(err) )

Removes a resource from the system

Arguments

    resource {String} Resource to be removed
    callback {Function} Callback called when finished.

allow( roles, resources, permissions, function(err) )

Adds the given permissions to the given roles over the given resources.

Arguments

    roles       {String|Array} role(s) to add permissions to.
    resources   {String|Array} resource(s) to add permisisons to.
    permissions {String|Array} permission(s) to add to the roles over the resources.
    callback    {Function} Callback called when finished.

allow( permissionsArray, function(err) )

Arguments

    permissionsArray {Array} Array with objects expressing what permissions to give.
       [{roles:{String|Array}, allows:[{resources:{String|Array}, permissions:{String|Array}]]

    callback         {Function} Callback called when finished.

removeAllow( role, resources, permissions, function(err) )

Remove permissions from the given roles owned by the given role.

Note: we loose atomicity when removing empty role_resources.

Arguments

    role        {String}
    resources   {String|Array}
    permissions {String|Array}
    callback    {Function}

allowedPermissions( userId, resources, function(err, obj) )

Returns all the allowable permissions a given user have to access the given resources.

It returns an array of objects where every object maps a resource name to a list of permissions for that resource.

Arguments

    userId    {String|Number} User id.
    resources {String|Array} resource(s) to ask permissions for.
    callback  {Function} Callback called when finished.

isAllowed( userId, resource, permissions, function(err, allowed) )

Checks if the given user is allowed to access the resource for the given permissions (note: it must fulfill all the permissions).

Arguments

    userId      {String|Number} User id.
    resource    {String} resource to ask permissions for.
    permissions {String|Array} asked permissions.
    callback    {Function} Callback called wish the result.

areAnyRolesAllowed( roles, resource, permissions, function(err, allowed) )

Returns true if any of the given roles have the right permissions.

Arguments

    roles       {String|Array} Role(s) to check the permissions for.
    resource    {String} resource to ask permissions for.
    permissions {String|Array} asked permissions.
    callback    {Function} Callback called wish the result.

whatResources(role, function(err, {resourceName: [permissions]})

Returns what resources a given role has permissions over.

Arguments

    role        {String|Array} Roles
    callback    {Function} Callback called with the result.

whatResources(role, permissions, function(err, resources) )

Returns what resources a role has the given permissions over.

Arguments

    role        {String|Array} Roles
    permissions {String[Array} Permissions
    callback    {Function} Callback called wish the result.

middleware( [numPathComponents, userId, permissions] )

Middleware for express.

Arguments

    numPathComponents {Number} number of components in the url to be considered part of the resource name.
    userId               {String|Number} the user id for the acl system (or if not specified, req.userId)
    permissions       {Array} the permissions to check for.

backend( db, [prefix] )

Creates a backend instance. All backends except Memory require driver or database instance.

Arguments

    db           {Object} Database instance
    prefix       {String} Optional collection prefix
var mongodb = require('mongodb'); 
mongodb.connect("mongodb://127.0.0.1:27017/acltest", function(error, db) {
  var mongoBackend = new acl.mongodbBackend(db, 'acl_');
});

Creates a new MongoDB backend using database instance db.

var client = require('redis').createClient(6379, '127.0.0.1', {no_ready_check: true});
var redisBackend = new redisBackend(client);

Creates a new Redis backend using Redis client client.

Tests

Run tests with npm (requires mocha):

 npm test

Future work

  • Support for denials (deny a role a given permission)

License

(The MIT License)

Copyright (c) 2011-2013 Manuel Astudillo manuel@optimalbits.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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