Hey everyone, here’s an idea, what do you think? (Please stop me…)
I have a few remote servers where disk encryption is only a moderately important measure; I definitely want to keep it but I’m also annoyed by having to ssh into it during the initrd-phase to provide a passkey on every reboot. What I would like is to get a notification with a link to my idp for some device flow, allowing me to authorize the server to obtain the secrets necessary for decryption.
As far as I can tell, this hasn’t been done before, or have I missed something? A naive idea would be to have custom oidc-claims for the different servers where the value is the luks-passphrase. Feels like a bad idea, though. Any ideas on the details as to how? I obviously don’t want to bloat my initrd-image, so a bash script using curl would be ideal.
Ironically, the passphrase for the encryption wouldn’t be encrypted in this scenario as claims can be decoded from the token payload if intercepted. It would also probably be stored as-is server side as well. Claims aren’t designed as secrets.
Perhaps you could authorise a request to an actual secrets manager via oidc though, allowing the volume to be unlocked.
Yes, I was thinking about storing encrypted keys, but still, using claims is clearly just wrong… Using a vault to store the key is probably the way to go, even though it adds another service the setup depends on.
A fall-back to the current way of unlocking the volume would probably be a good idea. It wouldn’t be fun to lose access to something because a cloud service went down or access to it was lost etc.
Definitely! I have bmc/kvm everywhere (well, everywhere that matters).
I have talked myself out of this (for now), though. I think if I ever find the time to revisit this, I will try to to it by injecting some oidc-based approval (memo to myself: ciba flow?) into something like clevis/tang.