Control Groups | Vault - HashiCorp Learn

Enterprise Only: Control Groups requires Vault Enterprise with the Governance & Policy Module.

Control Groups add additional authorization factors to be required before processing requests to increase the governance, accountability, and security of your secrets. When a control group is required for a request, the requesting client receives the wrapping token in return. Only when all authorizations are satisfied, the wrapping token can be used to unwrap the requested secrets.

»Personas

The end-to-end scenario described in this tutorial involves three personas:

admin with privileged permissions to create policies and identities
processor with permission to approve secret access
controller with limited permission to access secrets

»Challenge

In order to operate in EU, a company must abide by the General Data Protection Regulation (GDPR) as of May 2018. The regulation enforces two or more controllers jointly determine the purposes and means of processing (Chapter 4: Controller and Processor).

Consider the following scenarios:

Anytime an authorized user requests to read data at "EU_GDPR_data/data/orders/*", at least two people from the Security group must approve to ensure that the user has a valid business reason for requesting the data.
Anytime a database configuration is updated, it requires that one person from the DBA and one person from Security group must approve it.

»Solution

Use Control Groups in your policies to implement dual controller authorization required.

»Prerequisites

To perform the tasks described in this tutorial, you need to have a Vault Enterprise environment.

NOTE: To explore Vault Enterprise features, you can sign up for a free 30-day trial from here.

This tutorial assumes that you have some hands-on experience with ACL policies as well as Identities. If you are not familiar, go through the following guides first:

»Policy requirements

Since this tutorial demonstrates the creation of policies, log in with a highly privileged token such as root. Otherwise, required permissions to perform the steps in this tutorial are.

# Create and manage ACL policies
path "sys/policies/acl/*"
{
  capabilities = ["create", "read", "update", "delete", "list", "sudo"]
}

# To enable secrets engines
path "sys/mounts/*" {
  capabilities = [ "create", "read", "update", "delete" ]
}

# Setting up test data
path "EU_GDPR_data/*"
{
  capabilities = ["create", "read", "update", "delete", "list"]
}

# Manage userpass auth method
path "auth/userpass/*"
{
  capabilities = ["create", "read", "update", "delete", "list"]
}

# List, create, update, and delete auth methods
path "sys/auth/*"
{
  capabilities = ["create", "read", "update", "delete"]
}

# Create and manage entities and groups
path "identity/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

»Scenario Introduction

The scenario in this tutorial is that a user, Bob Smith has read-only permission on the "EU_GDPR_data/data/orders/*" path; however, someone in the acct_manager group must approve it before he can actually read the data.

As a member of the acct_manager group, Ellen Wright can authorize Bob's request.

Scenario

You are going to perform the following:

Implement a control group
Deploy the policies
Setup entities and a group
Verification
ACL Policies vs. Sentinel Policies

Step 1, 2 and 3 are the tasks need to be performed by administrators or operators who have the privileges to create policies and configure entities and groups.

»Step 1: Implement a control group

Author a policy named read-gdpr-order.hcl.

Bob needs read permissions on EU_GDPR_data/data/orders/*.

path "EU_GDPR_data/data/orders/*" {
  capabilities = [ "read" ]
}

Now, add control group to this policy:

path "EU_GDPR_data/data/orders/*" {
  capabilities = [ "read" ]

  control_group = {
    factor "authorizer" {
        identity {
            group_names = [ "acct_manager" ]
            approvals = 1
        }
    }
  }
}

For the purpose of this tutorial, the number of approvals is set to 1 to keep it simple and easy to test. Any member of the identity group, acct_manager can approve the read request. Although this example has only one factor (authorizer), you can add as many factor blocks as you need.

Now, write another policy for the acct_manager group named acct_manager.hcl.

# To approve the request
path "sys/control-group/authorize" {
    capabilities = ["create", "update"]
}

# To check control group request status
path "sys/control-group/request" {
    capabilities = ["create", "update"]
}

NOTE: The important thing here is that the authorizer (acct_manager) must have create and update permission on the sys/control-group/authorize endpoint so that they can approve the request.

»Step 2: Deploy the policies

Deploy the read-gdpr-order and acct_manager policies that you wrote.

Create a new policy named read-gdpr-order.

$ vault policy write read-gdpr-order read-gdpr-order.hcl

Create a new policy named acct_manager.

$ vault policy write acct_manager acct_manager.hcl

»Step 3: Setup entities and a group

This step only demonstrates CLI commands and Web UI to create entities and groups. Refer to the Identity - Entities and Groups tutorial if you need the full details.

Now you have policies, let's create a user, bob and an acct_manager group with ellen as a group member.

NOTE: For the purpose of this tutorial, use the userpass auth method to create user bob and ellen so that the scenario can be easily tested.

The following command uses jq tool to parse JSON output.

Enable the userpass auth method.
```
$ vault auth enable userpass
```

Create a new user, bob with password, "training".

$ vault write auth/userpass/users/bob password="training"

Create a new user, ellen with password, "training".

$ vault write auth/userpass/users/ellen password="training"

Retrieve the userpass mount accessor and save it in a file named accessor.txt.

$ vault auth list -format=json | jq -r '.["userpass/"].accessor' > accessor.txt

Create Bob Smith entity and save the identity ID in the entity_id_bob.txt.

$ vault write -format=json identity/entity name="Bob Smith" \
        policies="read-gdpr-order" \
        metadata=team="Processor" \
        | jq -r ".data.id" > entity_id_bob.txt

Add an entity alias for the Bob Smith entity.

$ vault write identity/entity-alias name="bob" \
      canonical_id=$(cat entity_id_bob.txt) \
      mount_accessor=$(cat accessor.txt)

Create Ellen Wright entity and save the identity ID in the entity_id_ellen.txt.

$ vault write -format=json identity/entity name="Ellen Wright" \
        policies="default" \
        metadata=team="Acct Controller" \
        | jq -r ".data.id" > entity_id_ellen.txt

Add an entity alias for the Ellen Wright entity.

$ vault write identity/entity-alias name="ellen" \
      canonical_id=$(cat entity_id_ellen.txt) \
      mount_accessor=$(cat accessor.txt)

Finally, create acct_manager group and add Ellen Wright entity as a member.

$ vault write identity/group name="acct_manager" \
      policies="acct_manager" \
      member_entity_ids=$(cat entity_id_ellen.txt)

»Step 4: Verification

Now, let's see how the control group works.

First, enable the key/value secrets engine at EU_GDPR_data.
```
$ vault secrets enable -path=EU_GDPR_data -version=2 kv
```

Write some mock data.

$ vault kv put EU_GDPR_data/orders/acct1 \
        order_number="12345678" product_id="987654321"

$ vault login -method=userpass username="bob" password="training"

Request to read "EU_GDPR_data/orders/acct1".

$ vault kv get EU_GDPR_data/orders/acct1

Key                              Value
---                              -----
wrapping_token:                  s.h9jGEBexp0o7vQhmImZKAAKo
wrapping_accessor:               HDUlEfkrbrfPOlfUnwgar025
wrapping_token_ttl:              24h
wrapping_token_creation_time:    2019-05-10 16:38:36 -0700 PDT
wrapping_token_creation_path:    EU_GDPR_data/data/orders/acct1

The response includes wrapping_token and wrapping_accessor. Export their values as environment variables for use in later steps.

NOTE: Be sure to replace the example wrapping_token and wrapping_accessor values with your actual values.

Export the wrapping token value as WRAPPING_TOKEN.

$ export WRAPPING_TOKEN=s.h9jGEBexp0o7vQhmImZKAAKo

Export the wrapping token accessor as WRAPPING_ACCESSOR.

$ export WRAPPING_ACCESSOR=HDUlEfkrbrfPOlfUnwgar025

Now, a member of acct_manager must approve this request. Log in as ellen who is a member of acct_manager group.
```
$ vault login -method=userpass username="ellen" password="training"
```

As a user, ellen, you can check and authorize bob's request using the following commands.

To check the current status:

$ vault write sys/control-group/request accessor=$WRAPPING_ACCESSOR

To approve the request:

$ vault write sys/control-group/authorize accessor=$WRAPPING_ACCESSOR

Example:

Check the current status.

$ vault write sys/control-group/request accessor=$WRAPPING_ACCESSOR
Key               Value
---               -----
approved          false
authorizations    <nil>
request_entity    map[name:Bob Smith id:38700386-723d-3d65-43b7-4fb44d7e6c30]
request_path      EU_GDPR_data/orders/acct1

Approve the request.

$ vault write sys/control-group/authorize accessor=$WRAPPING_ACCESSOR
Key         Value
---         -----
approved    true

Now, the approved status is true.

Since the control group requires one approval from a member of acct_manager group, the condition has been met. Log back in as bob and unwrap the secret.

Example:

Log back in as bob using the userpass auth method.

$ vault login -method=userpass username="bob" password="training"

Unwrap the secrets by passing the $WRAPPING_TOKEN environment variable.

$ vault unwrap $WRAPPING_TOKEN
Key         Value
---         -----
data        map[order_number:12345678 product_id:987654321]
metadata    map[created_time:2021-03-24T16:25:20.405776245Z deletion_time: destroyed:false version:1]

»Step 5: ACL Policy vs. Sentinel Policy

Although the read-gdpr-order.hcl was written as ACL policy, you can implement Control Groups in either ACL or Sentinel policies.

Using Sentinel, the same policy may look something like.

import "controlgroup"

control_group = func() {
  numAuthzs = 0
  for controlgroup.authorizations as authz {
      if "acct_manager" in authz.groups.by_name {
         numAuthzs = numAuthzs + 1
      }
  }
  if numAuthzs >= 1 {
      return true
  }
  return false
}

main = rule {
   control_group()
}

Deploy this policy as an Endpoint Governing Policy attached to "EU_GDPR_data/data/orders/*" path.

Refer to the Sentinel Properties documentation for the list of available properties associated with control groups.

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