Write RBAC for NestJS

#javascript #nestjs #rbac

Hello there!

Recently, I came across with the difficulty of finding a good solution to Role-based access control (RBAC) for NestJS so I decided to make my own:).
The done repository is here

Quick Start

For using RBAC there is need to implement IStorageRbac

export interface IStorageRbac {
  roles: string[];
  permissions: object;
  grants: object;
  filters: { [key: string]: any | IFilterPermission };
}

For instance:

export const RBACstorage: IStorageRbac = {
  roles: ['admin', 'user'],
  permissions: {
    permission1: ['create', 'update', 'delete'],
    permission2: ['create', 'update', 'delete'],
    permission3: ['filter1', 'filter2', RBAC_REQUEST_FILTER],
    permission4: ['create', 'update', 'delete'],
  },
  grants: {
    admin: [
      '&user',
      'permission1',
      'permission3',
    ],
    user: ['permission2', 'permission1@create', 'permission3@filter1'],
  },
  filters: {
    filter1: TestFilterOne,
    filter2: TestFilterTwo,
    [RBAC_REQUEST_FILTER]: RequestFilter,
  },
};

Storage consists of the following keys:

roles: array of roles

permissions: objects of permissions which content actions

grants: objects of assigned permission to roles

filters: objects of customs roles

Grant symbols

&: extends grant by another grant, for instance admin extends user (only support one level inheritance)

@: a particular action from permission, for instance permission1@update

Using RBAC like an unchangeable storage

import { Module } from '@nestjs/common';
import { RBAcModule } from 'nestjs-rbac';

@Module({
  imports: [
    RBAcModule.forRoot(RBAC),
  ],
  controllers: []
})
export class AppModule {}

Using RBAC like a dynamic storage

There is enough to implement IDynamicStorageRbac interface.

import { Module } from '@nestjs/common';
import { RBAcModule } from 'nestjs-rbac';

@Module({
  imports: [
    RBAcModule.forDynamic(AsyncService),
  ],
  controllers: []
})
export class AppModule {}
// implement dynamic storage
import { IDynamicStorageRbac, IStorageRbac } from 'nestjs-rbac';
@Injectable()
export class AsyncService implements IDynamicStorageRbac {
  constructor(
    private readonly repository: AnyRepository
  ) {

  }
  async getRbac(): Promise<IStorageRbac> {
      return  await this.repository.getRbac(); //use any persistence storage for getting RBAC
  }
}

Using for routers

import { RBAcPermissions, RBAcGuard } from 'nestjs-rbac';

@Controller()
export class RbacTestController {

  @RBAcPermissions('permission', 'permission@create')
  @UseGuards(
    AuthGuard, // need for using user into the request
    RBAcGuard,
  )
  @Get('/')
  async test1(): Promise<boolean> {
    return true;
  }
}

Using like service

import { RbacService} from 'nestjs-rbac';

@Controller()
export class RbacTestController {

  constructor(
    private readonly rbac: RbacService
  ){}

  @Get('/')
  async test1(): Promise<boolean> {
    await this.rbac.getRole(role).can('permission', 'permission@create');
    return true;
  }
}

Using the custom filters

filter is a great opportunity of customising behaviour RBAC.
For creating filter, there is need to implement IFilterPermission interface, which requires for implementing can method, and bind a key filter with filter implementation, like below:

export const RBAC: IStorageRbac = {
  roles: ['role'],
  permissions: {
    permission1: ['filter1'],
  },
  grants: {
    role: [
      `permission1@filter1`
    ],
  },
  filters: {
    filter1: TestFilter,
  },
};  
//===================== implementing filter
import { IFilterPermission} from 'nestjs-rbac';

export class TestFilter implements IFilterPermission {

  can(params?: any[]): boolean {
    return params[0];
  }

}

ParamsFilter services for passing arguments into particular filter:

const filter = new ParamsFilter();
filter.setParam('filter1', some payload);

const res = await rbacService.getRole('admin', filter).can(
  'permission1@filter1',
);

Also RBAC has a default filter RBAC_REQUEST_FILTER which has request object as argument:

Example:

//===================== filter
export class RequestFilter implements IFilterPermission {

  can(params?: any[]): boolean {
    return params[0].headers['test-header'] === 'test';
  }
}
//===================== storage
export const RBAC: IStorageRbac = {
  roles: ['role'],
  permissions: {
    permission1: ['filter1', 'filter2', RBAC_REQUEST_FILTER],
  },
  grants: {
    role: [
      `permission1@${RBAC_REQUEST_FILTER}`
    ],
  },
  filters: {
    [RBAC_REQUEST_FILTER]: RequestFilter,
  },
};  
//===================== using for routes
  @RBAcPermissions(`permission1@${RBAC_REQUEST_FILTER}`)
  @UseGuards(
    AuthGuard,
    RBAcGuard,
  )
  @Get('/')
  async test4(): Promise<boolean> {
    return true;
  }