narmitag / vault-unseal

vault-unseal -- auto-unseal utility for Hashicorp Vault

vault-unseal -- auto-unseal utility for Hashicorp Vault

Table of Contents

• Why
• Solution
• Installation
  • Docker
  • Ubuntu/Debian
  • CentOS/Redhat
  • Manual Install
  • Build from source
• Usage
• Contributing
• TODO
• License

Why

Depending on your use-case for Vault, you may or may not have opted for Vault Enterprise. If you have not, auto-unseal functionality for on-prem is currently only in enterprise (for cloud, it is now in the OSS version). If what you are storing in vault isn't sensitive enough to require human intervention, you may want to roll your own unseal functionality. The problem with this is it is very hard to do safely.

So, what do we need to solve? we want to auto-unseal a vault, by providing the necessary unseal tokens when we find vault is sealed. We also want to make sure we're sending notifications when this happens, so if vault was unsealed unintentionally (not patching, upgrades, etc), possibly related to crashing or malicious intent, a human can investigate at a later time (not 3am in the morning).

Solution

The goal for this project is to find the best way to unseal vault in a way that doesn't compromise too much security (a good balance between security and ease of use/uptime), without the requirement of Vault Enterprise, or having to move to a cloud platform.

We do this by running multiple instances of vault-unseal (you could run one on each node in the cluster). Each instance of vault-unseal is given a subset of the unseal tokens. You want to give each node just enough tokens, that when paired with another vault-unseal node, they can work together to unseal the vault. What we want to avoid is giving a single vault-unseal instance enough tokens to unseal (to prevent a compromise leading to enough tokens being exposed that could unseal the vault). Let's use the following example:

• cluster-1 consists of 3 nodes:
  • node-1
  • node-2
  • node-3
• cluster-1 is configured with 5 unseal tokens (tokens A, B, and C), but 3 are required to unseal a given vault node.
• given there are 3 nodes, and 3 tokens are required:
  • vault-unseal on node-1 gets tokens A and B.
  • vault-unseal on node-2 gets tokens B and C.
  • vault-unseal on node-3 gets tokens A and C.

With the above configuration:

• Given each vault-unseal node, each node has two tokens.
• Given the tokens provided to vault-unseal, each token (A, B, and C), there are two instances of that token across nodes in the cluster.
• If node-1 is completely hard-offline, nodes node-2 and node-3 should have all three tokens, so if the other two nodes reboot, as long as vault-unseal starts up on those nodes, vault-unseal will be able to unseal both.
• If node-2 becomes compromised, and the tokens are read from the config file (note: vault-unseal will not start if the permissions on the file aren't 600), this will not be enough tokens to unseal the vault.
• vault-unseal runs as root, with root permissions.

Installation

Check out the releases page for prebuilt versions. vault-unseal should work on ubuntu/debian, centos/redhat/fedora, etc. Below are example commands of how you would install the utility.

Docker

$ docker run -it --rm lrstanley/vault-unseal:latest

Ubuntu/Debian

$ wget https://liam.sh/ghr/vault-unseal_<version>_linux_amd64.deb
$ dpkg -i vault-unseal_<version>_linux_amd64.deb
$ vault-unseal --help

CentOS/Redhat

$ yum localinstall https://liam.sh/ghr/vault-unseal_<version>_linux_amd64.rpm
$ vault-unseal --help

Some older CentOS versions may require (if you get Cannot open: <url>. Skipping.):

$ wget https://liam.sh/ghr/vault-unseal_<version>_linux_amd64.rpm
$ yum localinstall vault-unseal_<version>_linux_amd64.rpm

Manual Install

$ wget https://liam.sh/ghr/vault-unseal_<version>_linux_amd64.tar.gz
$ tar -C /usr/bin/ -xzvf vault-unseal_<version>_linux_amd64.tar.gz vault-unseal
$ chmod +x /usr/bin/vault-unseal
$ vault-unseal --help

Source

Note that you must have Go installed (latest is usually best).

$ git clone https://github.com/lrstanley/vault-unseal.git && cd vault-unseal
$ make
$ ./vault-unseal --help

Usage

The default configuration path is /etc/vault-unseal.yaml when using deb/rpm. If you are not using these package formats, copy the example config file, example.vault-unseal.yaml, to vault-unseal.yaml. Note, all fields can be provided via environment variables (vault-unseal also supports .env files).

$ ./vault-unseal --help
Usage:
  vault-unseal [OPTIONS]

Application Options:
  -v, --version          Display the version of vault-unseal and exit
  -l, --log-path=PATH    Optional path to log output to
  -c, --config=PATH      Path to configuration file (default: ./vault-unseal.yaml)

Help Options:
  -h, --help             Show this help message

Contributing

Please review the CONTRIBUTING doc for submitting issues/a guide on submitting pull requests and helping out.

TODO

• add option to use vault token/another vault instance to obtain keys (e.g. as long the leader is online)?
• memory obfuscating/removing from memory right after unseal?

License

MIT License

Copyright (c) 2018 Liam Stanley <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.