Implementing Fine-Grained Access Control with Relationship-Based Access Control (#ReBAC) in Open Policy Agent (#OPA) #CIAM
Open Policy Agent (OPA) is a powerful open source policy engine that can be used to enforce access control policies in cloud-native applications. OPA is highly flexible and extensible, and it can be used to implement a wide range of authorization policies.
In this blog post, we will show how to implement fine-grained access control in a banking application using OPA and Relationship-based access control (ReBAC). Relationship-based access control (ReBAC) is an access control method that determines access rights based on the relationships between users and resources.
We will start by defining the access control rules, and then we will show how to implement those rules in OPA. Finally, we will show how the application can query OPA to check for authorization before processing a request.
Defining the Access Control Rules
The first step is to define the access control rules. In this example, we will define the following rules:
Implementing the Access Control Rules in OPA
Once the access control rules have been defined, they can be implemented in OPA using the Rego language. Rego is a powerful policy language that can be used to express a wide range of authorization policies.
The following Rego code defines the access control rules for the banking application using ReBAC:
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package com.example.banking
import data.Roles
import data.Accounts
rule customer_account_view {
??allow {
????input.user.roles == Roles.Customer &&
????input.account.owner == input.user.id
??}
}
rule customer_account_update {
??allow {
????input.user.relationships == [
??????{
????????type: "is-assigned-to",
????????target: input.account.owner
??????}
????]
??}
}
rule customer_account_delete {
??allow {
????input.user.roles == Roles.SystemAdministrator
??}
}
Querying OPA for an Authorization Decision
Once the access control rules have been implemented in OPA, the application can query OPA to check for authorization before processing a request. To do this, the application can make a HTTP request to OPA with the following parameters:
OPA will then evaluate the access control rules and return a decision. If the user is authorized to access the requested resource, OPA will return a 200 OK response. If the user is not authorized to access the requested resource, OPA will return a 403 Forbidden response.
The following code shows how the application can query OPA for an authorization decision:
import requests
def is_authorized(method, resource, user, relationships):
??url = "https://localhost:8180/v1/data/com.example.banking/" + resource
??headers = {
????"Authorization": "Bearer " + user.token
??}
??data = {
????"method": method,
????"relationships": relationships
??}
??response = requests.post(url, headers=headers, data=data)
??if response.status_code == 200:
????return True
??else:
????return False
The following code shows how the application can use the is_authorized function to check for authorization before processing a request:
if is_authorized("GET", "accounts/123456789", user, [
??{
????type: "is-assigned-to",
????target: user.id
??}
]):
??# Process the request
else:
??# The user is not authorized to access the requested resource
I hope this blog post has given you a better understanding of how to implement fine-grained access control with OPA and ReBAC. If you are interested in learning more about this approach, please reach out to me. I would be happy to discuss your specific needs and help you implement a solution that meets your requirements.
Principal Information Security Engineer @ RGA
1 年Need 2 read up on this, thx for sharing ????