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role-acl

3.3.4 • Public • Published

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Role, Attribute and conditions based Access Control for Node.js

npm i role-acl --save

Many RBAC (Role-Based Access Control) implementations differ, but the basics is widely adopted since it simulates real life role (job) assignments. But while data is getting more and more complex; you need to define policies on resources, subjects or even environments. This is called ABAC (Attribute-Based Access Control).

With the idea of merging the best features of the two (see this NIST paper); this library implements RBAC basics and also focuses on resource, action attributes and conditions.

This library is an extension of AccessControl. But I removed support for possession and deny statements from orginal implementation.

Core Features

  • Chainable, friendly API.
    e.g. ac.can(role).execute('create').on(resource)
  • Role hierarchical inheritance.
  • Define grants at once (e.g. from database result) or one by one.
  • Grant permissions by resources and actions define by glob notation.
  • Grant permissions by attributes defined by glob notation (with nested object support).
  • Ability to filter data (model) instance by allowed attributes.
  • Ability to control access using conditions.
  • Supports AND, OR, NOT, EQUALS, NOT_EQUALS, STARTS_WITH, LIST_CONTAINS conditions.
  • You can specify dynamic context values in the conditions using JSON Paths.
  • You can define your own condition functions too but please note if you use custom functions instead of standard conditions, you won't be able to save them as json in the DB.
  • Policies are JSON compatible so can be stored and retrieved from database.
  • Fast. (Grants are stored in memory, no database queries.)
  • TypeScript support.

Guide

const AccessControl = require('role-acl');
// or:
// import { AccessControl } from 'role-acl';

Basic Example

Define roles and grants one by one.

const ac = new AccessControl();
ac.grant('user')                    // define new or modify existing role. also takes an array.
    .execute('create').on('video')             // equivalent to .execute('create').on('video', ['*'])
    .execute('delete').on('video')
    .execute('read').on('video')
  .grant('admin')                   // switch to another role without breaking the chain
    .extend('user')                 // inherit role capabilities. also takes an array
    .execute('update').on('video', ['title'])  // explicitly defined attributes
    .execute('delete').on('video');
 
const permission = ac.can('user').execute('create').on('video');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['*'] (all attributes)
 
permission = ac.can('admin').execute('update').on('video');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['title']

Conditions Examples

const ac = new AccessControl();
ac.grant('user').condition(
    {
        Fn: 'EQUALS',
        args: {
            'category': 'sports'
        }
    }).execute('create').on('article');
 
let permission = ac.can('user').context({ category: 'sports' }).execute('create').on('article');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['*'] (all attributes)
 
permission = ac.can('user').context({ category: 'tech' }).execute('create').on('article');
console.log(permission.granted);    // —> false
console.log(permission.attributes); // —> []
 
// Condition with dynamic context values using JSONPath
// We can use this to allow only owner of the article to edit it
ac.grant('user').condition(
    {
        Fn: 'EQUALS',
        args: {
            'requester': '$.owner'
        }
    }).execute('edit').on('article');
 
permission = ac.can('user').context({ requester: 'dilip', owner: 'dilip' }).execute('edit').on('article');
console.log(permission.granted);    // —> true
 
// We can use this to prevent someone to approve their own article so that it goes to review 
// by someone else before publishing
ac.grant('user').condition(
    {
        Fn: 'NOT_EQUALS',
        args: {
            'requester': '$.owner'
        }
    }).execute('approve').on('article');
 
permission = ac.can('user').context({ requester: 'dilip', owner: 'dilip' }).execute('approve').on('article');
console.log(permission.granted);    // —> false
 
// Using custom/own condition functions
ac.grant('user').condition(
    (context) => {
        return context.category !== 'politics'
    }
).execute('create').on('article');
permission = ac.can('user').context({ category: 'sports' }).execute('create').on('article');
console.log(permission.granted);    // —> true

Wildcard (glob notation) Resource and Actions Examples

ac.grant({
    role: 'politics/editor',
    action: '*',
    resource: 'article',
    condition: {Fn: 'EQUALS', args: {category: 'politics'}},
    attributes: ['*']
});
ac.grant({
    role: 'politics/writer',
    action: ['*', '!publish'],
    resource: 'article',
    condition: {Fn: 'EQUALS', args: {category: 'politics'}},
    attributes: ['*']
});
 
ac.grant({
    role: 'admin',
    action: '*',
    resource: '*',
    condition: {Fn: 'EQUALS', args: {category: 'politics'}},
    attributes: ['*']
});
permission = ac.can('politics/editor').execute('publish').with({category: 'politics'}).on('article');
console(permission.attributes); // -> ['*']
console(permission.granted); // -> true
 
permission = ac.can('admin').execute('publish').with({category: 'politics'}).on('article');
console(permission.attributes); // -> ['*']
console(permission.granted); // -> true
 
permission = ac.can('admin').execute('publish').with({category: 'politics'}).on('blog');
console(permission.attributes); // -> ['*']
console(permission.granted); // -> true
 
permission = ac.can('politics/writer').execute('publish').with({category: 'politics'}).on('article');
console(permission.granted); // -> false

Express.js Example

Check role permissions for the requested resource and action, if granted; respond with filtered attributes.

const ac = new AccessControl(grants);
// ...
router.get('/videos/:title', function (req, res, next) {
    const permission = ac.can(req.user.role).execute('read').on('video');
    if (permission.granted) {
        Video.find(req.params.title, function (err, data) {
            if (err || !data) return res.status(404).end();
            // filter data by permission attributes and send.
            res.json(permission.filter(data));
        });
    } else {
        // resource is forbidden for this user/role
        res.status(403).end();
    }
});

Roles

You can create/define roles simply by calling .grant(<role>) method on an AccessControl instance.

Roles can extend other roles.

// user role inherits viewer role permissions
ac.grant('user').extend('viewer');
// admin role inherits both user and editor role permissions
ac.grant('admin').extend(['user', 'editor']);
// both admin and superadmin roles inherit moderator permissions
ac.grant(['admin', 'superadmin']).extend('moderator');

Actions and Action-Attributes

ac.grant('editor').execute('publish').on('article');
let permission = ac.can('editor').execute('publish').on('article');
console(permission.attributes); // —> ['*'] (all attributes)
console(permission.granted); // -> true
 
ac.grant('sports/editor').execute('publish').when({Fn: 'EQUALS', args: {category: 'sports'}}).on('article');
permission = ac.can('sports/editor').execute('publish').with({category: 'sports'}).on('article');
console(permission.attributes); // —> ['*'] (all attributes)
console(permission.granted); // -> true
 
permission = ac.can('sports/editor').execute('publish').with({category: 'politics'})).on('article');
console(permission.attributes); // -> []
console(permission.granted); // -> false

Resources and Resource-Attributes

Multiple roles can have access to a specific resource. But depending on the context, you may need to limit the contents of the resource for specific roles.

This is possible by resource attributes. You can use Glob notation to define allowed or denied attributes.

For example, we have a video resource that has the following attributes: id, title and runtime. All attributes of any video resource can be read by an admin role:

ac.grant('admin').execute('read').on('video', ['*']);
// equivalent to:
// ac.grant('admin').execute('read').on('video');

But the id attribute should not be read by a user role.

ac.grant('user').execute('read').on('video', ['*', '!id']);
// equivalent to:
// ac.grant('user').execute('read').on('video', ['title', 'runtime']);

You can also use nested objects (attributes).

ac.grant('user').execute('read').on('account', ['*', '!record.id']);

Checking Permissions and Filtering Attributes

You can call .can(<role>).<action>(<resource>) on an AccessControl instance to check for granted permissions for a specific resource and action.

const permission = ac.can('user').execute('read').on('account');
permission.granted;       // true
permission.attributes;    // ['*', '!record.id']
permission.filter(data);  // filtered data (without record.id)

See express.js example.

Defining All Grants at Once

You can pass the grants directly to the AccessControl constructor. It accepts either an Object:

// This is actually how the grants are maintained internally.
let grantsObject = {
    admin: {
        grants: [
            {
                resource: 'video', action: '*', attributes: ['*']
            }
        ]
    },
    user: {
        grants: [
            {
                resource: 'video', action: 'create', attributes: ['*']
            },
            {
                resource: 'video', action: 'read', attributes: ['*']
            },
            {
                resource: 'video', action: 'update', attributes: ['*']
            },
            {
                resource: 'video', action: 'delete', attributes: ['*']
            },
        ]
    },
    "sports/editor": {
        grants: [
            {
                resource: 'article',
                action: '*',
                attributes: ["*"],
                condition: {
                    Fn: 'EQUALS',
                    args: {
                        'category': 'sports'
                    }
                }
            }   
        ] 
    },
    "sports/writer": {
        grants: [
            {
                resource: 'article',
                action: ['create', 'update'],
                attributes: ["*", "!status"],
                condition: {
                    Fn: 'EQUALS',
                    args: {
                        'category': 'sports'
                    }
                }
            }   
        ] 
    }
};
 
const ac = new AccessControl(grantsObject);

... or an Array (useful when fetched from a database):

// grant list fetched from Database (to be converted to a valid grants object, internally)
let grantList = [
    { role: 'admin', resource: 'video', action: 'create', attributes: ['*'] },
    { role: 'admin', resource: 'video', action: 'read', attributes: ['*'] },
    { role: 'admin', resource: 'video', action: 'update', attributes: ['*'] },
    { role: 'admin', resource: 'video', action: 'delete', attributes: ['*'] },
 
    { role: 'user', resource: 'video', action: 'create', attributes: ['*'] },
    { role: 'user', resource: 'video', action: 'read', attributes: ['*'] },
    { role: 'user', resource: 'video', action: 'update', attributes: ['*'] },
    { role: 'user', resource: 'video', action: 'delete', attributes: ['*'] },
    { role: 'user', resource: 'photo', action: '*', attributes: ['*'] },
    { role: 'user', resource: 'article', action: ['*', '!delete'], attributes: ['*'] },
    { role: 'sports/editor', resource: 'article', action: 'create', attributes: ['*'],
      condition: { "Fn": "EQUALS", "args": { "category": "sports" } }
    },
    {
        role: 'sports/editor', resource: 'article', action: 'update', attributes: ['*'],
        condition: { "Fn": "EQUALS", "args": { "category": "sports" } }
    }
];
const ac = new AccessControl(grantList);

You can set/get grants any time:

const ac = new AccessControl();
ac.setGrants(grantsObject);
console.log(ac.getGrants());
// You can save ac.getGrants() to Database
// Please note: User should be part of your code and wraps calls to User to table/collection.
await User.save({permissions: JSON.stringify(acl.getGrants())}); 
// Retrieve from DB
const perms = await User.getBydId(userId);
ac.setGrants(JSON.parse(user.permissions));
 
// if your DB supports storing JSON natively then you can use following code.
await User.save({permissions: acl.getGrants()}); 
// Retrieve from DB
const perms = await User.getBydId(userId);
ac.setGrants(user.permissions);

Extending Roles

const ac = new AccessControl();
const editorGrant = {
    role: 'editor',
    resource: 'post',
    action: 'create', // action
    attributes: ['*'] // grant only
};
ac.grant(editorGrant);
// first level of extension (extending with condition)
ac.extendRole('sports/editor', 'editor', {Fn: 'EQUALS', args: {category: 'sports'}});
ac.extendRole('politics/editor', 'editor', {Fn: 'EQUALS', args: {category: 'politics'}});
 
let permission = ac.can('sports/editor').context({category: 'sports'}).execute('create').on('post');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['*']
 
permission = ac.can('sports/editor').context({category: 'politics'}).execute('create').on('post');
console.log(permission.granted);    // —> false
console.log(permission.attributes); // —> []
 
// second level of extension (extending without condition)
ac.extendRole('sports-and-politics/editor', ['sports/editor', 'politics/editor']);
permission = ac.can('sports-and-politics/editor').context({category: 'politics'}).execute('create').on('post');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['*']
 
// third level of extension (extending with condition)
ac.extendRole('conditonal/sports-and-politics/editor', 'sports-and-politics/editor', {
    Fn: 'EQUALS',
    args: { status: 'draft' }
});
permission = ac.can('conditonal/sports-and-politics/editor').context({category: 'politics', status: 'draft'}).execute('create').on('post');
console.log(permission.granted);    // —> true
console.log(permission.attributes); // —> ['*']
 
permission = ac.can('conditonal/sports-and-politics/editor').context({category: 'politics', status: 'published'}).execute('create').on('post');
console.log(permission.granted);    // —> false
console.log(permission.attributes); // —> []

Allowed Resources and actions

const ac = new AccessControl();
ac.grant('user').condition({Fn: 'EQUALS', args: {category: 'sports'}}).execute('create').on('article');
ac.grant('user').execute('*').on('image');
ac.extendRole('admin', 'user');
ac.grant('admin').execute('delete').on('article');        
ac.grant('admin').execute('*').on('category');
ac.extendRole('owner', 'admin');
ac.grant('owner').execute('*').on('video');
 
console.log(ac.allowedResources({role: 'user'}).sort()); // -> ['article', 'image']
console.log(ac.allowedResources({role: 'user', context: {category: 'politics'}}).sort()); // -> ['image']       
console.log(ac.allowedResources({role: 'admin'}).sort()); // -> ['article', 'category', 'image']
console.log(ac.allowedResources({role: 'owner'}).sort()); // -> ['article', 'category', 'image', 'video']
console.log(ac.allowedResources({role: ['admin', 'owner']}).sort()); // -> ['article', 'category', 'image', 'video']
 
console.log(ac.allowedActions({role: 'user', resource: 'article'}).sort()); // -> ['create']
console.log(ac.allowedActions({role: 'user', resource: 'article', context: {category: 'politics'}})); // -> []        
console.log(ac.allowedActions({role: ['admin', 'user'], resource: 'article'}).sort()); // -> ['create', 'delete']
console.log(ac.allowedActions({role: 'admin', resource: 'category'}).sort()); // -> ['*']
console.log(ac.allowedActions({role: 'owner', resource: 'video'}).sort()); // -> ['*']

NOTE: allowedResources and allowedActions skip the conditions when context is not passed

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npm i role-acl

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263

version

3.3.4

license

MIT

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