Keylime

Keylime is the verifier that judges a running folly node's boot. It is being introduced in stages. Today the repo holds its boot policy; fleetd's hourly check still decides, as Identity describes. fleetd keeps intake, the LDevID and LAK, the NetBox lifecycle and the consequences of a failed boot.

How it works#

Keylime's verifier replays a node's UEFI event log against the quoted PCRs, then asks a measured-boot policy whether the boot is acceptable. The policy here is fleetd-profile, in apps/keylime-policy/lolwtf_mb_policy.py. It reads the same profile fleetd reads, apps/fleetd/attest/policy/<name>.yaml, rendered to JSON by apps/fleetd/cmd/keylime-policy-render into clusters/folly/apps/keylime/policies/, and makes the same checks in the same words as Policy.evaluate in apps/fleetd/attest/policy.go: the platform key, the key exchange keys, the required and allowed db entries, the authorities before and after the separator, and the pinned boot applications.

mise run keylime:render-policies writes the reference states. A Go test fails when a committed file differs from a fresh render. apps/keylime-policy/testdata/cases.json names the verdicts both verifiers must give riptide's boot, and mise run keylime:test and the Go tests in apps/fleetd/attest/ both assert every case.

Limits#

• Talos's kernel has no IMA, so the evidence is PCRs 0 to 7 and the event log. There is no runtime file integrity.
• The policy judges the running node. Intake, which requires the HookOS signing authority, stays fleetd's.

Reference#

• Policy: apps/keylime-policy/
• Renderer: apps/fleetd/cmd/keylime-policy-render/
• Reference states: clusters/folly/apps/keylime/policies/