In Nomad 1.4, we implemented a root keyring to support encrypting Variables and
signing Workload Identities. The keyring was originally stored with the
AEAD-wrapped DEKs and the KEK together in a JSON keystore file on disk. We
recently added support for using an external KMS for the KEK to improve the
security model for the keyring. But we've encountered multiple instances of the
keystore files not getting backed up separately from the Raft snapshot,
resulting in failure to restore clusters from backup.
Move Nomad's root keyring into Raft (encrypted with a KMS/Vault where available)
in order to eliminate operational problems with the separate on-disk keystore.
Fixes: https://github.com/hashicorp/nomad/issues/23665
Ref: https://hashicorp.atlassian.net/browse/NET-10523
We use capped exponential backoff in several places in the code when handling
failures. The code we've copy-and-pasted all over has a check to see if the
backoff is greater than the limit, but this check happens after the bitshift and
we always increment the number of attempts. This causes an overflow with a
fairly small number of failures (ex. at one place I tested it occurs after only
24 iterations), resulting in a negative backoff which then never recovers. The
backoff becomes a tight loop consuming resources and/or DoS'ing a Nomad RPC
handler or an external API such as Vault. Note this doesn't occur in places
where we cap the number of iterations so the loop breaks (usually to return an
error), so long as the number of iterations is reasonable.
Introduce a helper with a check on the cap before the bitshift to avoid overflow in all
places this can occur.
Fixes: #18199
Co-authored-by: stswidwinski <stan.swidwinski@gmail.com>
