policy-opa

README

Hexa Integration Support for Open Policy Agent (OPA)

This project provides support for running Hexa IDQL Policy on Open Policy Agent (OPA) servers. This integration includes:

• Hexa rego policy to evaluate IDQL policy statements in an OPA Policy Agent.
• An OPA hexaFilter plugin enabling dynamic evaluation of IDQL Conditions.
• An extended OPA server hexaOpa which runs as a normal OPA server but with the hexaFilter extension.
• A client opaTools package which enables web applications to call OPA using a normalized query providing request and subject information for processing
• A testBundleServer which can be used to deploy policy to one or more OPA Agents.
• Supported as an integration with the Hexa Mapper Project.

Introducing the Hexa OPA Server Integration

This integration of OPA follows the Open Policy Agent extension mechanism to enable the processing if IDQL Condition clauses. The HexaOpa server is a normal OPA server and can run any rego policy. A docker image is available at: independentid/hexaopa.

Running hexaOpa works the same way as for opa. For more information, see the Open Policy Agent Deployment Guide.

Building and Running Hexa OPA Locally

Prerequisites:

• Go Lang 1.21
• Docker
• Git client

With the above pre-requisites installed, clone the repository, change directory into the project and run the build.sh shell script. This will build a local docker image called hexaopa

git clone https://hexa-org/policy-mapper

cd policy-mapper

sh ./build.sh

Once the image is built, use docker-compose.yml to start the testBundleServer and hexaOpa servers.

docker compose up

When the bundle-server container starts up, it will automatically generate self-signed TLS certificates to enable encrypted communication between OPA and the test bundle server. If you wish to use your own certificates, update the docker-compose environment variables to point to the appropriate directory/files. See .env for a list of environment variables supported.

Using HexaOpa In Docker-Compose or K8S

The HexaOpa image is available in the independentid/hexaopa docker repository. To use these images in a K8S configuration or docker-compose, reference the image independentid/hexaopa:latest.

Enabling Go Applications with OPA and IDQL

An OPA Client is simply an application (a policy enforcement point or PAP) that makes a request to an OPA server to request a policy decision.

To make a request, a client application may use the client/hexaOpaClient package to call PrepareInput to prepare an input object to pass to OPA.

func (w http.ResponseWriter, r *http.Request) {
    client := &http.Client{Timeout: time.Minute * 2}
    
    input := opaTools.PrepareInput(r)
    inputBytes, _ := json.Marshal(input)
    body := bytes.NewReader(inputBytes)
    req, err := http.NewRequest(http.MethodPost, "http://hexa-opa-server/v1/data/hexaPolicy", body)
    req.Header.Set("Authorization", someauth)  // authorization for OPA queries if needed
    
    resp, err := client.Do(req)
    . . .
}

In the above code, the input is prepared to pass to the OPA server. If you are using opaTools, the input will look something like:

{
    "req": {
        "ip": "127.0.0.1:65151",
        "protocol": "HTTP/1.1",
        "method": "GET",
        "path": "/testpath",
        "param": {
            "a": [
                "b"
            ],
            "c": [
                "d"
            ]
        },
        "header": {
            "Accept-Encoding": [
                "gzip"
            ],
            "Authorization": [
                "Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJ0ZXN0SXNzdWVyIiwic3ViIjoiQmFzaWNCb2IiLCJhdWQiOlsidGVzdEF1ZGllbmNlIl0sImV4cCI6MTcxMDkwNzUyNywicm9sZXMiOiJiZWFyZXIgYWJjIn0.uBStTYLxJi5g0tZr_4RlixJmin6waDYOl4L_g7cGilU"
            ],
            "User-Agent": [
                "Go-http-client/1.1"
            ]
        },
        "time": "2024-03-19T21:00:29.825416-07:00"
    },
    "subject": {
        "roles": [
            "bearer",
            "abc"
        ],
        "expires": "2024-03-19T21:05:27-07:00",
        "type": "Bearer+JWT",
        "sub": "BasicBob",
        "iss": "testIssuer",
        "aud": [
            "testAudience"
        ],
        "iat": "0001-01-01T00:00:00Z",
        "nbf": "0001-01-01T00:00:00Z"
    }
}

When run against the example IDQL in /server/hexaFilter/test/bundle/bundle_test/data-V1.json, the following JSON is returned:

{
    "actionRights": [
        "TestIPMaskCanary/ietf:http:!PUT:/testpath*",
        "TestIPMaskCanary/ietf:http:GET:/testpath*",
        "TestIPMaskCanary/ietf:http:POST:/testpath*",
       . . .
        "TestJwtMember/ietf:http:POST:/testpath*",
        "TestJwtMember/ietf:http:PUT:/testpath*",
        "TestJwtRole/ietf:http:GET:/testpath*",
        "TestJwtRole/ietf:http:POST:/testpath*"
    ],
    "allow": true,
    "allowSet": [
        "TestIPMaskCanary",
        "TestIPMaskCanaryNotDelete",
        "TestIPMaskCanaryPOST",
        "TestJwtCanary",
        "TestJwtMember",
        "TestJwtRole"
    ]
}

In the above response, allow indicates the request is allowed. allowSet indicates all of the policies that might apply to the subject (BasicBob), and actionRights indicates all of the policies and actions that are enabled. The attributes actionRights and allowSet are provided to enable applications to control UI presentation such as what buttons to enable or disable.

In another example, the hexaFilter rego extension enables the ability to evaluate input structures provided by client/hexaOpaClient request builder using a condition clause in IDQL in the Hexa Rego script. In this example, in order for the request to be allowed, the user (subject) must be "BasicBob", and they must have a JWT authorization token with the role "abc" that is issued by "testIssuer". Additionally, the HTTP request must be either a GET or POST to the path /testpath* where * is a wildcard to match any path beginning with /testpath.

Example IDQL with Condition Statement:

{
  "meta": {
    "version": "0.6",
    "date": "2021-08-01 21:32:44 UTC",
    "description": "Test that allows jwt authenticated specific subject *and* has a role",
    "policyId": "TestJwtRole"
  },
  "subject": {
    "members" : ["user:BaSicBob"]
  },
  "actions": [
    {
      "actionUri": "ietf:http:POST:/testpath*"
    },
    {
      "actionUri": "ietf:http:GET:/testpath*"
    }
  ],
  "object": {
    "resource_id": "CanaryProfileService"
  },
  "condition": {
    "rule": "subject.type eq jwt and subject.iss eq testIssuer and subject.aud co testAudience and subject.roles co abc",
    "action": "allow"
  }
}

The relevant enhancement in the above IDQL is:

"condition": {
  "rule": "subject.type eq jwt and subject.iss eq testIssuer and subject.aud co testAudience and subject.roles co abc",
  "action": "allow"
}

In the condition clause above, the authentication type is matched as jwt, the issuer and audience are also matched to the values testIssuer and testAudience, and finally the user is checked for the role "abc". Note that this example is a bit hypothetical since the "actions" already test permissible actions using the actionURI. The exmaple provided is mainly to demonstrate that multiple conditions can be tested with and and or clauses as per the IDQL specification.

Hexa Input for IDQL Policies

When using the client/hexaOpaClient go package to prepare your authorization request the following attributes are prepared that can be submitted to the Open Policy Agent service. While any attribute can be referenced in a condition rule, the column IDQL Use indicates how the attribute is used in IDQL clauses.

Category	Attribute	Type	Description	IDQL Use
req	ip	string	The client TCP/IP address and port (e.g. 127.0.0.1:65151)	members (net:)
	protocol	string	The request protocol (http)
	method	string	The HTTP Method (GET, DELETE, PATCH, POST, PUT)	Actions (ietf:http:)
	path	string	The path of the request (e.g. /Users )	Actions (ietf:http:)
	param	map[string][]string	A map of all URL query parameters (e.g. /?a=b&c=d
	header	map[string][]string	A map of all HTTP Headers
	time	time.Time	The date and time the request was received
	actionUris	[]string	Client app supplied: actionUri(s) to be invoked	Actions (uri value)
	resourceIds	[]string	Client app supplied: The resource_id(s) of the requesting app	Object (resource_id)
subject	type	string	The type of authentication (Anonymous basic, or jwt)
	sub	string	The JWT 'sub" value or the Basic Auth username	Members (user:, domain:)
	roles	[]string	Roles asserted in a JWT assertion	Members (role:)
	claims	map[string]interface{}	The set of claims received in a JWT assertion
	expires	time.Time	The expiry time of the JWT received
	iat	time.Time	The time the JWT was issued
	nbf	time.Time	A time before which the certificate should be ignored
	iss	string	The issuer of the received JWT
	aud	[]string	An array of values indicating valud audiences for the use of the token

For any value above, OPA reqo will process this variables. For example input.subject.type refers to the type of authentication.

Writing IDQL Policy for the HexaOpa

In OPA Rego, IDQL policy is submitted in a JSON format as data input to OPA servers. The hexaPolicy rego package is then used to compare input (previous section) with IDQL data to determine if an access is allowed.

The following is a template for a typical IDQL policy. The values in brackets are described below:

{
  "meta": {
    "version": "<idql_version>",
    "date": "<date>",
    "description": "<descriptive text>",
    "policyId": "<policyId>"
  },
  "subject": {
    "members": [
      "<type>:<member>"
    ]
  },
  "actions": [
    {
      "actionUri": "<actionUri>"
    }
  ],
  "condition": {
    "rule": "<idql-filter>",
    "action": "<allow|deny>"
  },
  "object": {
    "resource_id": "<app-resource-id>"
  }
}

IDQL field values, format and how to use:

Field	Format	Use	Description
idql_version	n.n (typically 0.6)	Informational	Typically reflects the current IDQL version from hexa-org/policy-mapper.
policyId	string	Required - OPA returns policy ids in allowSet	Used to identify which IDQL policy was matched in rego
type:member	multi-value string	Matches input subjects	Types: any, anyAuthenticated, user:username/sub, domain:domainsuffix, role:rolename, net:cidr
			any means any user or anonymous subject anyAuthenticated means any authenticated subject user matches input.subject.sub (e.g. basicbob@hexa.org) domain matches the suffix of input.subject.sub (e.g. @hexa.org) role matches input.subject.roles (e.g. admin) net matches a CIDR with input.req.ip (e.g. 198.51.100.14/24)
actionUri		Returned in actionRights	One of two forms:
	urn:name	Logical rights permitted	Matches against input.request.actionUris(asserted by the calling application)
	ietf:http:method:path	HTTP Requests Permitted	method is one of GET, DELETE, PATCH, POST, PUT, or * for any method path is the request path (* to wildcard)
app-resource-id	string	The name of the resource the policy is associated with	Matches against input.request.resourceIds
idql-filter	SCIM Filter	Run-time attribute conditions	Filter matches against OPA input attributes (e.g. input.subject.type eq jwt)
allow deny	allow (default) or deny	Determines the outcome of condition	If filter is true the policy matches if action is allow. Policy does not match if action is deny.