sunjizzle/diskless-workstation
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

tpm-enrol: move signing key off the EK slot 0x81010001 → 0x81000100

Browse Source 
Bench (Proxmox vTPM, host cygnus-cruiser-99) confirmed via tpm2_readpublic that
0x81010001 — the handle our design used for the fleet signing key — is the
TCG-standard RSA Endorsement Key slot: the object there is the swtpm-provisioned
EK (restricted|decrypt|adminwithpolicy, RSA-2048/AES128CFB, canonical EK
authPolicy 837197…, EK cert at NV 0x1c00002). Most firmware/swtpm TPMs occupy
that slot, so EnsureKey could never create our key there — it errored reading
the EK as ECC and enrolment died before the CSR/POST.

Move the fleet signing key to 0x81000100, a non-reserved owner persistent
handle (clear of EK 0x81010001/2 and SRK 0x81000001/2). Threaded through:
  - fleet-enrol -handle default + new rd.dot1x.handle= cmdline knob (baked by
    extract-artifacts.sh, overridable via SMBIOS)
  - files/etc/dot1x/wpa_supplicant-dot1x.conf private_key handle
  - the dracut hook, bench tpm-provision.sh / tpm-selftest.sh
  - CLAUDE.md invariant #1 + design/SSP docs + TODO #11
NV index 0x01800001 (owner range) is unchanged.

EnsureKey hardening: refuse to evict any restricted-decrypt object (EK/SRK) as
a safety net — never clobber the TPM endorsement/storage identity (also
protects the future EK/AK attestation path). Still self-heals a genuine stale
signing key. New regression TestEnsureKeyRefusesToEvictProtectedKey; the
stale-key regression and handle constants moved to 0x81000100.

Design note records the IDevID (0x81020001) option for the later EK/AK
attestation work. Follow-up items logged: content-aware NV presence check
(verify the cert chains to the fleet CA, so leftover/foreign NV can't suppress
enrolment) and a de-enrol/TPM-reset procedure.
This commit is contained in:
Audiobuzz
2026-07-02 12:19:59 +00:00
parent 4c55ed4b26
commit 4d6f038e3c
17 changed files with 201 additions and 61 deletions
Download Patch File Download Diff File Expand all files Collapse all files
files/enrol/main.go
+3 -2
View File
@@ -2,7 +2,8 @@
//
// Invoked from the dracut hook (95dot1x-macsec/tpm-enrol.sh) ONLY when the
// secure build boots a host whose TPM NV 0x01800001 is empty. It:
// 1. ensures an ECDSA signing key exists at TPM handle 0x81010001,
// 1. ensures an ECDSA signing key exists at a non-reserved owner handle
// (default 0x81000100 — deliberately NOT the EK slot 0x81010001),
// 2. builds a CSR with it (key never leaves the TPM),
// 3. submits CSR + device context to the enrolment broker, shows the returned
// fingerprint on the Plymouth splash, and polls until an admin approves,
@@ -42,7 +43,7 @@ func main() {
url = flag.String("url", "http://boot.fleet.lab/enrol", "enrolment broker base URL")
tpmPath = flag.String("tpm", "/dev/tpmrm0", "TPM device path")
nvHex = flag.String("nvindex", "0x01800001", "TPM NV index for the client cert")
handleHex = flag.String("handle", "0x81010001", "TPM persistent handle for the signing key")
handleHex = flag.String("handle", "0x81000100", "TPM persistent handle for the signing key (non-reserved owner handle; NOT the EK slot 0x81010001)")
cn = flag.String("cn", "fleet-host", "CSR CommonName (generic; identity is the cert serial)")
iface = flag.String("iface", "", "network interface for the device-context MAC")
caFile = flag.String("cacert", "/etc/dot1x/radius-ca.pem", "CA bundle for an https broker URL")