6.11. Configuring Keylime for measured boot attestation

Procedure

1. On the monitored system where the Keylime agent is configured and running, install the python3-keylime package, which contains the keylime-policy tool:

   # dnf -y install python3-keylime

2. On the monitored system, generate a policy from the measured boot log of the current state of the system by using the keylime-policy tool:

   # keylime-policy create measured-boot --eventlog-file /sys/kernel/security/tpm0/binary_bios_measurements --output <./measured_boot_reference_state.json>

   • Replace <./measured_boot_reference_state.json> with the path where keylime-policy saves the generated policy.

   • If your UEFI system does not have Secure Boot enabled, pass the --without-secureboot argument.

     중요

     The policy generated with keylime-policy is based on the current state of the system and is very strict. Any modifications of the system including kernel updates and system updates will change the boot process and the system will fail the attestation.

3. Copy the generated policy to the system where the keylime_tenant utility is configured, for example:

   # scp root@<agent_ip>:<./measured_boot_reference_state.json> <./measured_boot_reference_state.json>

4. On the system where the Keylime tenant is configured, provision the agent by using the keylime_tenant utility:

   # keylime_tenant --command add --targethost <agent_ip> --uuid <agent_uuid> --mb_refstate <./measured_boot_reference_state.json> --cert default

   • Replace <agent_ip> with the agent’s IP address.
   • Replace <agent_uuid> with the agent’s UUID.
   • Replace <./measured_boot_reference_state.json> with the path to the measured boot policy.

   If you configure measured boot in combination with runtime monitoring, provide all the options from both use cases when entering the keylime_tenant --command add command.

   참고

   You can stop Keylime from monitoring a node by using the # keylime_tenant --command delete --targethost <agent_ip> --uuid <agent_uuid> command.

   You can modify the configuration of an already registered agent by using the keylime_tenant --command update command.

Verification

1. Reboot the monitored system and verify a successful attestation of the agent:

   # keylime_tenant --command cvstatus --uuid <agent_uuid>
   ...
   {"<agent_uuid>": {"operational_state": "Get Quote"..."attestation_count": 5
   ...

   Replace <agent_uuid> with the agent’s UUID.

   If the value of operational_state is Get Quote and attestation_count is nonzero, the attestation of this agent is successful.

   If the value of operational_state is Invalid Quote or Failed attestation fails, the command displays output similar to the following:

   {"<agent_uuid>": {"operational_state": "Invalid Quote", ... "ima.validation.ima-ng.not_in_allowlist", "attestation_count": 5, "last_received_quote": 1684150329, "last_successful_attestation": 1684150327}}

2. If the attestation fails, display more details in the verifier log:

   # journalctl -u keylime_verifier
   {"d432fbb3-d2f1-4a97-9ef7-75bd81c00000": {"operational_state": "Tenant Quote Failed", ... "last_event_id": "measured_boot.invalid_pcr_0", "attestation_count": 0, "last_received_quote": 1684487093, "last_successful_attestation": 0}}