Vault Plugin: JWT Auth Backend

This is a standalone backend plugin for use with Hashicorp Vault. This plugin allows for JWTs (including OIDC tokens) to authenticate with Vault.

Please note: We take OpenBao's security and our users' trust very seriously. If you believe you have found a security issue in OpenBao, please responsibly disclose by contacting us at [email protected].

Quick Links

- Vault Website: https://www.vaultproject.io
- JWT Auth Docs: https://developer.hashicorp.com/vault/docs/auth/jwt
- Main Project Github: https://www.github.com/hashicorp/vault

Getting Started

This is a Vault plugin and is meant to work with Vault. This guide assumes you have already installed Vault and have a basic understanding of how Vault works.

Otherwise, first read this guide on how to get started with Vault.

To learn specifically about how plugins work, see documentation on Vault plugins.

Usage

Please see documentation for the plugin on the Vault website.

This plugin is currently built into Vault and by default is accessed at auth/jwt. To enable this in a running Vault server:

$ vault auth enable jwt
Successfully enabled 'jwt' at 'jwt'!

To see all the supported paths, see the JWT auth backend docs.

Developing

If you wish to work on this plugin, you'll first need Go installed on your machine.

For local dev first make sure Go is properly installed, including setting up a GOPATH. Next, clone this repository into $GOPATH/src/github.com/hashicorp/vault-plugin-auth-jwt. You can then download any required build tools by bootstrapping your environment:

$ make bootstrap

To compile a development version of this plugin, run make or make dev. This will put the plugin binary in the bin and $GOPATH/bin folders. dev mode will only generate the binary for your platform and is faster:

$ make
$ make dev

Put the plugin binary into a location of your choice. This directory will be specified as the plugin_directory in the Vault config used to start the server.

plugin_directory = "path/to/plugin/directory"

Start a Vault server with this config file:

$ vault server -config=path/to/config.hcl ...
...

Once the server is started, register the plugin in the Vault server's plugin catalog:

$ vault plugin register \
        -sha256=<SHA256 Hex value of the plugin binary> \
        -command="vault-plugin-auth-jwt" \
        auth \
        jwt
...
Success! Data written to: sys/plugins/catalog/jwt

Note you should generate a new sha256 checksum if you have made changes to the plugin. Example using openssl:

openssl dgst -sha256 $GOPATH/vault-plugin-auth-jwt
...
SHA256(.../go/bin/vault-plugin-auth-jwt)= 896c13c0f5305daed381952a128322e02bc28a57d0c862a78cbc2ea66e8c6fa1

Enable the auth plugin backend using the JWT auth plugin:

$ vault auth enable -plugin-name='jwt' plugin
...

Successfully enabled 'plugin' at 'jwt'!

Provider-specific handling

Provider-specific handling can be added by writing an object that conforms to one or more interfaces in provider_config.go. Some interfaces will be required, like CustomProvider, and others will be invoked if present during the login process (e.g. GroupsFetcher). The interfaces themselves will be small (usually a single method) as it is expected that the parts of the login that need specialization will be different per provider. This pattern allows us to start with a minimal set and add interfaces as necessary.

If a custom provider is configured on the backend object and satisfies a given interface, the interface will be used during the relevant part of the login flow. e.g. after an ID token has been received, the custom provider's UserInfoFetcher interface will be used, if present, to fetch and merge additional identity data.

The custom handlers will be standalone objects defined in their own file (one per provider). They'll be part of the main jwtauth package to avoid potential circular import issues.

Tests

If you are developing this plugin and want to verify it is still functioning (and you haven't broken anything else), we recommend running the tests.

To run the tests, invoke make test:

$ make test

You can also specify a TESTARGS variable to filter tests like so:

$ make test TESTARGS='--run=TestConfig'

Additionally, there are some BATs tests in the tests dir.

Prerequisites

• Install Bats Core
• Docker or a vault binary in the tests directory.

Setup

• Configure an OIDC provider
• Save and export the following values to your shell:
  • CLIENT_ID
  • CLIENT_SECRET
  • ISSUER
• Export VAULT_IMAGE to test the image of your choice or place a vault binary in the tests directory.
• Export VAULT_LICENSE. This test will only work for HashiCorp's Vault images.

Logs

Vault logs will be written to VAULT_OUTFILE. BATs test logs will be written to SETUP_TEARDOWN_OUTFILE.

Run Bats tests

# export env vars
export CLIENT_ID="12345"
export CLIENT_SECRET="6789"
export ISSUER="my-issuer-url"

# run tests
cd tests/
./test.bats