Policy Based Access Control
AWS IAM Policy inspired and (mostly) compatible evaluation engineUse the power and flexibility of the AWS IAM Policy syntax in your own application to manage access control. For more details on AWS IAM Policies have a look at https://docs.aws.amazon.com/IAM/latest/UserGuide/policiesoverview.html.
Installation
npm install pbac
Contents
- Properties - evaluate(params) - validate(policy) - Context
Synopsis
var PBAC = require('pbac');
var policies = [{
"Version": "2012-10-17",
"Statement": [{
"Sid": "OptionalDescription",
"Effect": "Allow",
"Action": [
"iam:CreateUser",
"iam:UpdateUser",
"iam:DeleteUser"
],
"Resource": [
"arn:aws:iam:::user/${req:UserName}"
],
"Condition": {
"IpAddress": {
"req:IpAddress": "10.0.20.0/24"
}
}
}]
}];
var pbac = new PBAC(policies);
// returns true
pbac.evaluate({
action: 'iam:CreateUser',
resource: 'arn:aws:iam:::user/testuser',
context: {
req: {
IpAddress: '10.0.20.51',
UserName: 'testuser',
}
}
});
Constructor
var pbac = new PBAC(policies, [options]);
Constructs a policy evaluator.
Properties
policies
(Array|Object)
options
(Object)
* `schema` (Object) - JSON schema that describes the policies. Defaults to the contents of schema.json that ships with this module.
* `validateSchema` (Boolean) - Validate the schema when the object is constructed. This can be disabled in production environment if it can be assumed that the schema is valid to improve performance when constructing new objects.
* `validatePolicies` (Boolean) - Policies passed to the constructor will be validated against the `schema`. Defaults to `true`. Can be disabled to improve performance if the policies can be assumed to be valid.
* `conditions` (Object) - Object of conditions that are supported in the `Conditions` attribute of policies. Defaults to `conditions.js` in this module. If conditions are passed to the constructor they will be merged with the conditions of the `conditions.js` module (with `conditions.js` taking precedence).
Methods
evaluate(params)
Tests an object against the policies and determines if the object passes. The method will first try to find a policy with an explicitDeny
for the combination of
resource
, action
and condition
(matching policy). If such policy exists, evaluate
returns false.
If there is no explicit deny the method will look for a matching policy with an explicit Allow
.
evaluate
will return true
if such a policy is found. If no matching can be found at all,
evaluate
will return false
. Please find a more thorough explanation of this process at https://docs.aws.amazon.com/IAM/latest/UserGuide/AccessPolicyLanguageEvaluationLogic.html.pbac.evaluate({
action: 'iam:CreateUser',
resource: 'arn:aws:iam:::user/testuser',
context: {
req: {
IpAddress: '10.0.20.51',
UserName: 'testuser',
}
}
});
Parameters
params
(Object)
* `action` (String) - Action to validate
* `resource` (String) - Resource to validate
* `context` (Object) - Nested object of context for interpolation of policy context. See [Context](#context).
Returns: boolean
, Returns true
if params
passes the policies, false
otherwisevalidate(policy)
Validates one or many policies against the schema provided in the constructor. Will throw an error if validation fails.Parameters
policy
(Array|Object)
Returns:
boolean
, Returns true
if the policies are validReference
Context
Have a look at https://docs.aws.amazon.com/IAM/latest/UserGuide/Policycontext.html to understand what policy context are, where they can be used and how they are interpreted. Theevaluate
method expects a context
parameter which is a nested object that translates to colon-separated context.Example:
var context = {
req: {
IpAddress: '10.0.20.51',
UserName: 'testuser',
},
session: {
LoggedInDate: '2015-09-29T15:12:42Z',
},
};
This would translate to the context
req:IpAddress
, req:UserName
and session:LoggedInDate
.The MIT License (MIT)
Copyright (c) 2018 Moritz Onken
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.