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Data Loss Prevention

Understanding DLP

Data Loss Prevention (DLP) is a method of ensuring that sensitive data isn’t logged or leaked. This is done by doing a series of regex replacements on the response body and content that is logged by Envoy (see Access Logging).

Valid regex patterns are those in the RE2 syntax. Note that some features such as lookaheads are not supported by RE2.

For example, we can use Gloo Gateway to transform this response:

{
   "fakevisa": "4397945340344828",
   "ssn": "123-45-6789"
}

into this response:

{
   "fakevisa": "XXXXXXXXXXXX4828",
   "ssn": "XXX-XX-X789"
}

DLP is configured as an ordered list of Actions on an HTTP listener, virtual service, or route. If configured on the listener, an additional matcher is paired with a list of Actions, and the first DLP rule that matches a request will be applied.

The DLP filter will be run by Envoy after any other filters which might add data to be masked into the dynamic metadata. Gloo Gateway’s current filter order follows:

Fault Stage (Fault injection)
DLP
CORS
Rest of the filters … (not all in the same stage)

DLP for access logs

By default, DLP will only run regex replacements on the response body. If access logging is configured, the DLP actions can also be applied to the headers and dynamic metadata that is logged by the configured access loggers. To do so, the enabledFor DLP configuration option must be set to ACCESS_LOGS or ALL (to mask access logs AND the response bodies).

WAF access logs will only be masked when logged to Dynamic metadata. WAF logs written to Filter State will not be masked.

Prerequisites

Install Gloo Gateway Enterprise.

Simple Example

In this example we will demonstrate masking responses using one of the predefined DLP Actions, rather than providing a custom regex.

First let’s begin by configuring a simple static upstream to an echo site.

kubectl
glooctl


kubectl apply -f - <<EOF
apiVersion: gloo.solo.io/v1
kind: Upstream
metadata:
  name: json-upstream
  namespace: gloo-system
spec:
  static:
    hosts:
      - addr: echo.jsontest.com
        port: 80
EOF


glooctl create upstream static --static-hosts echo.jsontest.com:80 --name json-upstream

Now let’s configure a simple virtual service to send requests to the upstream.

apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: vs
  namespace: gloo-system
spec:
  virtualHost:
    domains:
      - '*'
    routes:
      - routeAction:
          single:
            upstream:
              name: json-upstream
              namespace: gloo-system
        options:
          autoHostRewrite: true

Run the following curl to get the unmasked response:

curl $(glooctl proxy url)/ssn/123-45-6789/fakevisa/4397945340344828

The curl should return:

{
   "fakevisa": "4397945340344828",
   "ssn": "123-45-6789"
}

Now let’s mask the SSN and credit card, apply the following virtual service:

kubectl apply -f - <<EOF
apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: vs
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - routeAction:
        single:
          upstream:
            name: json-upstream
            namespace: gloo-system
      options:
        autoHostRewrite: true
    options:
      dlp:
        actions:
        - actionType: SSN
        - actionType: ALL_CREDIT_CARDS
EOF

Run the same curl as before:

curl $(glooctl proxy url)/ssn/123-45-6789/fakevisa/4397945340344828

This time it will return a masked response:

{
   "fakevisa": "XXXXXXXXXXXX4828",
   "ssn": "XXX-XX-X789"
}

As noted above, DLP can also mask access logs by using a configuration like:

    options:
      dlp:
        enabledFor: ALL
        actions:
        - actionType: SSN
        - actionType: ALL_CREDIT_CARDS

Custom Example

In this example we will demonstrate defining our own custom DLP Action, rather than leveraging one of the predefined regular expressions.

Let’s start by creating our typical petstore microservice:

kubectl apply -f https://raw.githubusercontent.com/solo-io/gloo/v1.14.x/example/petstore/petstore.yaml

Apply the following virtual service to route to the Gloo Gateway discovered petstore upstream:

kubectl apply -f - <<EOF
apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: vs
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - routeAction:
        single:
          upstream:
            name: default-petstore-8080
            namespace: gloo-system
EOF

Query the petstore microservice for a list of pets:

curl $(glooctl proxy url)/api/pets

You should obtain the following response:

[{"id":1,"name":"Dog","status":"available"},{"id":2,"name":"Cat","status":"pending"}]

Names are often used as personally identifying information, or PII. Let’s write our own regex to mask the names returned by the petstore service:

kubectl apply -f - <<EOF
apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: vs
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - routeAction:
        single:
          upstream:
            name: default-petstore-8080
            namespace: gloo-system
    options:
      dlp:
        actions:
        - customAction:
            maskChar: "X"
            name: test   # only used for logging
            percent:
              value: 60  # % of regex match to mask
            regexActions:
            - regex: '"name":[^"]*"([^"]*)"'
              subgroup: 1
EOF

Query for pets again:

curl $(glooctl proxy url)/api/pets

You should get a masked response:

[{"id":1,"name":"XXg","status":"available"},{"id":2,"name":"XXt","status":"pending"}]

Key/value (header masking) example

In this example, you define a key/value DLP action, which you can use to mask the value associated with a specified request header.

Predefined and Custom actions will only match based on header value in access logs. To match against a header name, use a key/value action.

Get started by creating the petstore microservice.

kubectl apply -f https://raw.githubusercontent.com/solo-io/gloo/v1.14.x/example/petstore/petstore.yaml

Apply the following virtual service to route to the Gloo Gateway discovered upstream for petstore.

apiVersion: gateway.solo.io/v1
kind: VirtualService
metadata:
  name: vs
  namespace: gloo-system
spec:
  virtualHost:
    domains:
    - '*'
    routes:
    - routeAction:
        single:
          upstream:
            name: default-petstore-8080
            namespace: gloo-system

Apply the following gateway definition, which configures the gateway-proxy deployment to log the value of the test-header request header.

apiVersion: gateway.solo.io/v1
kind: Gateway
metadata:
  name: gateway-proxy
  namespace: gloo-system
spec:
  bindAddress: '::'
  bindPort: 8080
  proxyNames:
  - gateway-proxy
  useProxyProto: false
  options:
    accessLoggingService:
      accessLog:
      - fileSink:
          stringFormat: "test-header: %REQ(test-header)%\n"
          path: /dev/stdout

Query the petstore microservice. The test-value value is specified for the test-header request header.
```
curl $(glooctl proxy url)/api/pets -H test-header:test-value
```
Get the access logs from the gateway-proxy deployment.
```
kubectl logs deployment/gateway-proxy -n gloo-system
```
Verify that you see the following log entry:
```
test-header: test-value 
```

To mask the value of the test-header request header, update the virtual service that you created in step 2 to use a DLP key/value matcher.

   apiVersion: gateway.solo.io/v1
   kind: VirtualService
   metadata:
     name: vs
     namespace: gloo-system
   spec:
     virtualHost:
       domains:
       - '*'
       routes:
       - routeAction:
           single:
             upstream:
               name: default-petstore-8080
               namespace: gloo-system
       options:
         dlp:
           enabledFor: ALL
           actions:
           - keyValueAction:
               maskChar: "*"
               name: test-header-mask   # only used for logging
               keyToMask: test-header
               percent:
                 value: 100  # % of regex match to mask
             actionType: KEYVALUE

Send another request to the petstore service.

curl $(glooctl proxy url)/api/pets -H test-header:test-value

Check the gateway-proxy access logs again.
```
kubectl logs deployment/gateway-proxy -n gloo-system
```
Verify that you see the following log entry, in which the value is masked:
```
test-header: ****-*****
```

Some notes on key/value actions:

You cannot use key/value actions to mask pseudo headers.
Key/value actions do not mask data in response bodies. They mask only the value of request headers, response headers, and dynamic metadata in access logs.
To apply key/value actions, you must set dlp.enabledFor to ALL or ACCESS_LOGS.

Summary

In this tutorial we installed Gloo Gateway Enterprise and demonstrated rewriting responses from upstreams with both the provided default regex patterns as well as the custom regex config.

Cleanup

kubectl delete vs vs -n gloo-system
kubectl delete us json-upstream -n gloo-system