Authorization (RBAC)

May 12, 2020 - By: Thomas Jungbauer ( Lastmod: 2021-08-14 )

Per default all requests inside a Service Mesh are allowed, which can be a problem security-wise. To solve this, authorization, which verifies if the user is allowed to perform a certain action, is required. Istio’s authorization provides access control on mesh-level, namespace-level and workload-level.

With the resource AuthorizationPolicy granular policies can be defined. These policies are loaded to and verified by the Envoy Proxy which then authorizes a request.

Implicit enablement

To enable authorization the only thing you need is to do is to define the AuthorizationPolicy. If the resource is not defined, then no access control will be used, instead any traffic is allowed. If AuthorizationPolicy is applied to a workload, then by default any traffic is denied unless it is explicitly allowed.

This is applicable to Service Mesh version 1.1+

Preparing Environment

The following steps will configure an example Role Based Access Control (RBAC). It will start from scratch. If you just want to quickly configure the authorization and have anything else in place, you can start form here: Configure Authentication Policy

Create a new project
```
oc new-project tutorial
```

Be sure that a Service Mesh Member Roll exists for this new project

cat <<'EOF' > memberroll.yaml
apiVersion: maistra.io/v1
kind: ServiceMeshMemberRoll
metadata:
  name: default
spec:
  members:
    - tutorial
EOF

oc apply -f memberroll.yaml -n istio-system

Clone and install the example application

git clone https://github.com/redhat-developer-demos/istio-tutorial/ istio-tutorial

oc apply -f istio-tutorial/customer/kubernetes/Deployment.yml -n tutorial
oc apply -f istio-tutorial/customer/kubernetes/Service.yml -n tutorial
oc expose service customer
oc apply -f istio-tutorial/preference/kubernetes/Deployment.yml -n tutorial
oc apply -f istio-tutorial/preference/kubernetes/Service.yml -n tutorial
oc apply -f istio-tutorial/recommendation/kubernetes/Deployment.yml -n tutorial
oc apply -f istio-tutorial/recommendation/kubernetes/Service.yml -n tutorial

Wait until all pods are running. There should be 2 containers for all pods:

oc get pods -w

Create Gateway and VirtualService

cat <<'EOF' > Gateway_VirtualService.yaml
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: customer-gateway
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: customer-gateway
spec:
  hosts:
  - "*"
  gateways:
  - customer-gateway
  http:
  - match:
    - uri:
        prefix: /customer
    rewrite:
      uri: /
    route:
    - destination:
        host: customer
        port:
          number: 8080
EOF

oc apply -f Gateway_VirtualService.yaml -n tutorial

Verify if the application is working You can either use the run.sh from previous tutorials, or simply try the following curl

export GATEWAY_URL=$(oc -n istio-system get route istio-ingressgateway -o jsonpath='{.spec.host}'); echo $GATEWAY_URL
curl $GATEWAY_URL/customer

This should return the following line:

customer => preference => recommendation v1 from 'f11b097f1dd0': 1

Optionally check the connection from inside the customer container

get pods name and enter it:

oc get pods
NAME                                 READY   STATUS    RESTARTS   AGE
customer-6948b8b959-dhsm9            2/2     Running   0          177m
preference-v1-7fdb89c86b-dvzs9       2/2     Running   0          177m
recommendation-v1-69db8d6c48-cjcpn   2/2     Running   0          177m

Connect into the container pod and try to reach the different microservices

oc rsh customer-6948b8b959-dhsm9

sh-4.4$ curl customer:8080
customer => preference => recommendation v1 from 'f11b097f1dd0': 2

sh-4.4$ curl preference:8080
preference => recommendation v1 from 'f11b097f1dd0': 3

sh-4.4$ curl recommendation:8080
recommendation v1 from 'f11b097f1dd0': 4

Configure Authentication Policy

Enabling User-End authentication

cat <<'EOF' > authentication-policy.yaml
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "customerjwt"
spec:
  targets:
    - name: customer
    - name: preference
    - name: recommendation
  origins:
    - jwt:
        issuer: "testing@secure.istio.io"
        jwksUri: "https://gist.githubusercontent.com/lordofthejars/7dad589384612d7a6e18398ac0f10065/raw/ea0f8e7b729fb1df25d4dc60bf17dee409aad204/jwks.json"
  principalBinding: USE_ORIGIN

EOF

oc apply -f authentication-policy.yaml -n tutorial

Access should be denied after a few seconds

curl $GATEWAY_URL/customer
Origin authentication failed.%

Use token to authenticate

token=$(curl https://gist.githubusercontent.com/lordofthejars/a02485d70c99eba70980e0a92b2c97ed/raw/f16b938464b01a2e721567217f672f11dc4ef565/token.simple.jwt -s)
curl -H "Authorization: Bearer $token" $GATEWAY_URL/customer

This will result in a correct response

customer => preference => recommendation v1 from 'f11b097f1dd0': 5

Configure Role Based Access Control (RBAC)

Create the resource AuthorizationPolicy

This is a new resources, supported since Service Mesh 1.1. It will allow GET method when the role equals to "customer"

cat <<'EOF' > AuthorizationPolicy.yaml
apiVersion: "security.istio.io/v1beta1"
kind: "AuthorizationPolicy"
metadata:
  name: "customer"
spec:
  rules:
  - to:
    - operation:
        methods: ["GET"]
    when:
    - key: request.auth.claims[role]
      values: ["customer"]
EOF

oc apply -f AuthorizationPolicy.yaml -n tutorial

Get a token for the role and retry to connect to the service,

token=$(curl https://gist.githubusercontent.com/lordofthejars/f590c80b8d83ea1244febb2c73954739/raw/21ec0ba0184726444d99018761cf0cd0ece35971/token.role.jwt -s)
curl -H "Authorization: Bearer $token" $GATEWAY_URL/customer

This results in:

customer => preference => recommendation v1 from 'f11b097f1dd0': 8

Let’s verify the setting and change the AuthorizationPolicy. This will break the authorization, since the token provides roles=customer and we set the Policy to "whereistherole"

cat <<'EOF' > AuthorizationPolicy-Hack.yaml
apiVersion: "security.istio.io/v1beta1"
kind: "AuthorizationPolicy"
metadata:
  name: "customer"
spec:
  rules:
  - to:
    - operation:
        methods: ["GET"]
    when:
    - key: request.auth.claims[role]
      values: ["whereistherole"]
EOF

oc replace -f AuthorizationPolicy-Hack.yaml -n tutorial

If you now try to access the service, with the token, which provides "customer" as role, it will lead to an error:

token=$(curl https://gist.githubusercontent.com/lordofthejars/f590c80b8d83ea1244febb2c73954739/raw/21ec0ba0184726444d99018761cf0cd0ece35971/token.role.jwt -s)
curl -H "Authorization: Bearer $token" $GATEWAY_URL/customer

RBAC: access denied