The Dell 820 kept "finding a cert" and bypassing enrolment despite repeated BIOS
TPM clears. tpm2_nvreadpublic revealed 0x01800001 on that hardware is a FIRMWARE
platform index (platformcreate|policydelete|writelocked, 70 bytes — not our
cert; siblings at 0x01800003/4 + 0x01810000). platformcreate survives TPM2_Clear
and policydelete needs the platform's secret policy, so it's permanent and
unusable by us — the blind check false-positived on it, and enrolment could
never write there anyway. Same class of bug as the EK-handle collision.
Move the NV cert index default 0x01800001 -> 0x01800100 (free on the 820, owner
range, overridable via rd.dot1x.nvindex): cmdline (extract-artifacts.sh),
fleet-enrol -nvindex, the dracut hooks, bench scripts, CLAUDE.md invariant #1,
and design/SSP docs. The signing-key handle (0x81000100) is unchanged.
Harden WriteNVCert: refuse a platformcreate index with a clear "pick a free
owner index via rd.dot1x.nvindex" error instead of a confusing undefine
failure. Regression simtest/TestWriteNVCertRefusesPlatformIndex; NV roundtrip +
ReadNVCert tests moved to 0x01800100. All go tests + packer validate pass.
The enrol trigger keyed on "is NV 0x01800001 defined/readable", so leftover
state (an earlier tpm-provision run — bench-seen on the 820: "cert present —
normal boot" with no real identity) or random bytes (tpm-selftest) silently
suppressed enrolment. Now content-aware:
- tpmkey.ReadNVCert reads the full NV contents (chunked).
- classifyNVCert (TPM-agnostic, unit-tested): parses X.509, checks validity
window, and when a real fleet CA bundle is present verifies the cert chains
to it. Only a valid fleet cert = enrolled.
- New `fleet-enrol -check-only` (no network/no key-gen) exits 0=valid cert,
20=enrol needed, 1=error. The full enrol path uses the same classification
instead of NVPresent.
- The dracut hook calls -check-only as the single gate, replacing the blind
tpm2_nvread (and its now-dead TPM2TOOLS_TCTI export). tpm2_nvread stays in
the initramfs for the secure path (dot1x-macsec-up.sh).
Lab fallback: the shipped radius-ca.pem is a placeholder (not a cert) ->
loadCAPool returns nil -> chain-less "parseable + unexpired" acceptance, so
reboot-converge doesn't loop; production replaces radius-ca.pem with the real
fleet CA for strict chaining.
Tests: classifyNVCert table (valid/expired/garbage/foreign/no-CA) + simtest
ReadNVCert roundtrip across the 512B chunk. All pass; packer validate clean.
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.
Bench boot failed with "fleet-enrol: ensure key at 0x81010001: key at handle
is not ECC: did not contain eccDetail (selector value was 1)": a real host had
an RSA key persisted at 0x81010001 (left by an older tpm2-tools/openssl
provisioning path), and EnsureKey fatally errored trying to read it as our ECC
signing key — so enrolment died before the CSR/POST and the host fell through
to a normal boot (no fingerprint, nothing at the broker).
EnsureKey now evicts a wrong-type/unusable key at the handle and creates a
fresh ECC key. Safe on the enrol path: it only runs on an empty-NV host, so no
issued cert references the old key. A valid ECC key is still reused (idempotent
retried enrol).
Regression: simtest TestEnsureKeyEvictsStaleNonECC pre-plants an RSA key and
asserts EnsureKey recreates a usable ECC signer (passes against the go-tpm
simulator).
Replaces the shell/openssl-provider host enrolment (a35f2d6) with a static
Go + go-tpm binary, and moves BOTH host Go binaries out of the Packer VM.
fleet-enrol (files/enrol/, Go + go-tpm, no CGO):
- talks to /dev/tpmrm0 DIRECTLY via transport.FromReadWriter(os.File) — no
linuxtpm, so go-tpm is the only dep and there is NO tpm2-tools key-gen /
openssl tpm2 provider / curl in the image (removes the biggest bench risk,
the provider handle: key-ref).
- ensures the ECDSA key @0x81010001, builds the CSR (crypto.Signer over the
TPM key), POSTs CSR+context to the broker, shows the Plymouth fingerprint,
polls /status, writes the leaf cert to NV 0x01800001.
- tpmkey/ is an exported package so the TPM ceremony is tested against the
go-tpm software simulator from a SEPARATE simtest/ module (CGO stays out of
the shipped build). Transaction logic (mock broker) tested in-package.
- deps pinned by go.sum (not vendored): the binary now builds on the CI
runner, which has network — reproducible via pinned Go 1.26.4 + go.sum.
Out-of-VM build (decision): both fleet-enrol AND fleet-hostapi compile in the
CI "Build host Go binaries" step (Go 1.26.4, CGO off, -trimpath) and Packer
FILE-PROVISIONS the static binaries in. Dropped the in-VM `dnf install golang`
+ the 2d removal — the Rocky build image carries no Go toolchain / go-tpm tree.
Wiring:
- tpm-enrol.sh: now a thin GATE (empty-NV check, pre-auth DHCP on en*,
exec /usr/sbin/fleet-enrol, reboot-to-converge). module-setup.sh bundles the
binary (asserted) + reverts the tpm2-openssl/curl installs.
- diskless.pkr.hcl: file provisioners for both binaries; enrol installed to
/usr/sbin before the initramfs build + fapolicyd-trusted; lsinitrd asserts
fleet-enrol; dnf reverted to baseline (no tpm2-openssl/curl).
- gitea-main-ci.yaml: Set up Go + build both binaries + run the simulator
ceremony test, before packer validate.
TESTED here: transaction unit tests + the full TPM ceremony (key-gen -> persist
-> ECDSA sign -> CSR verify -> chunked NV write -> re-enrol) against the go-tpm
simulator. BENCH-VERIFY (real/swtpm, empty owner auth, pre-auth DHCP, Plymouth,
reboot-converge, prod HTTPS) tracked in docs/TODO.md #11.
Audiobuzz