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shankar0123
a12a437664
SCEP RFC 8894 + Intune master bundle — Phase 6.5 of 14 (opt-in,
enterprise-procurement-checkbox).
Closes the procurement-team objection that 'shared password
authentication' is a checkbox-fail regardless of how strong the
password is. The clean answer: a sibling route that adds client-cert
auth at the handler layer AND keeps the challenge password (defense in
depth, not replacement). Devices present a bootstrap cert from a
trusted CA (e.g. a manufacturing-time cert), then SCEP-enroll for
their long-lived cert. Same model Apple's MDM and Cisco's BRSKI use.
internal/config/config.go
* SCEPProfileConfig gains MTLSEnabled bool + MTLSClientCATrustBundlePath
string. Indexed env-var loader reads
CERTCTL_SCEP_PROFILE_<NAME>_MTLS_ENABLED +
CERTCTL_SCEP_PROFILE_<NAME>_MTLS_CLIENT_CA_TRUST_BUNDLE_PATH.
* Validate() refuses MTLSEnabled=true with empty bundle path —
structural defense in depth ahead of the file-content preflight.
cmd/server/main.go
* preflightSCEPMTLSTrustBundle: file existence + PEM parse + ≥1
CERTIFICATE block + non-expired check. Returns the parsed
*x509.CertPool ready to inject into the per-profile SCEPHandler.
Failures os.Exit(1) with the offending PathID in the structured log.
* SCEP startup loop walks each profile; when MTLSEnabled, runs
preflight, builds the per-profile pool, contributes the bundle's
certs to the union pool that backs the TLS-layer
VerifyClientCertIfGiven, clones the SCEPHandler with
SetMTLSTrustPool, and registers the parallel sibling route via
apiRouter.RegisterSCEPMTLSHandlers.
* Union pool published to outer scope as scepMTLSUnionPoolForTLS;
passed to buildServerTLSConfigWithMTLS so the listener serves both
/scep[/<pathID>] (no client cert) and /scep-mtls/<pathID>
(cert required at handler layer) on the same socket.
* Final-handler dispatch gains /scep-mtls + /scep-mtls/* prefix
routing through the no-auth chain (auth boundary is the client
cert + challenge password, NOT a Bearer token).
cmd/server/tls.go
* New buildServerTLSConfigWithMTLS that wraps buildServerTLSConfig
+ sets ClientCAs + ClientAuth=VerifyClientCertIfGiven when a
non-nil pool is passed. nil pool = identical TLS shape to the
pre-Phase-6.5 builder (no behavior change for deploys without
mTLS profiles).
* Critical: VerifyClientCertIfGiven (NOT RequireAndVerifyClientCert)
so a client that doesn't present a cert can still hit the standard
/scep route. The per-profile gate at the handler layer enforces
'cert required' on /scep-mtls/<pathID>.
internal/api/handler/scep.go
* SCEPHandler gains mtlsTrustPool *x509.CertPool field +
SetMTLSTrustPool method. Per-profile pool injected by
cmd/server/main.go after preflight.
* HandleSCEPMTLS wrapper: gates on r.TLS.PeerCertificates non-empty
+ per-profile cert.Verify against THIS profile's pool. Returns
HTTP 401 for missing/untrusted cert (mTLS failure is auth, not
authorization). Returns HTTP 500 if mtlsTrustPool is nil (deploy
bug — the route shouldn't have been registered). On success
delegates to HandleSCEP — defense in depth: mTLS is additive,
NOT replacement; the standard SCEP code path including the
challenge-password gate still executes.
* Per-profile re-verification via cert.Verify(...) is critical:
the TLS layer verified against the UNION pool, so a cert that
chains to profile A's bundle would pass TLS even when targeting
profile B. The handler-layer gate prevents cross-profile
bleed-through.
internal/api/router/router.go
* AuthExemptDispatchPrefixes gains '/scep-mtls' (auth boundary is
client cert + challenge password, NOT Bearer token).
* RegisterSCEPMTLSHandlers parallel to RegisterSCEPHandlers:
empty PathID maps to /scep-mtls root; non-empty maps to
/scep-mtls/<pathID>. Each handler in the map MUST have had
SetMTLSTrustPool called.
internal/api/router/openapi_parity_test.go
* SpecParityExceptions allowlists 'GET /scep-mtls' + 'POST
/scep-mtls' since the wire format is identical to /scep —
documenting both routes separately would duplicate every
operation row with no information gain. Documented alternative
in docs/legacy-est-scep.md.
internal/api/handler/scep_mtls_test.go (new, ~210 LoC)
* 6 tests + 2 helpers covering the auth contract:
1. RejectsMissingClientCert — request with r.TLS=nil → 401
2. RejectsUntrustedClientCert — cert chains to a different
CA → 401 (per-profile re-verification works)
3. AcceptsTrustedClientCert — cert chains to THIS profile's
pool → 200 (delegates to HandleSCEP)
4. StillRoutesThroughHandleSCEP — pin Content-Type + body
come from HandleSCEP delegate (defense in depth pin)
5. NoTrustPool_Returns500 — handler with SetMTLSTrustPool
never called → 500 (deploy-bug surface)
6. StandardRoute_StillNoMTLS — pin /scep keeps working
without a client cert even when mTLS pool is set
* genSelfSignedECDSACA + signECDSAClientCert helpers materialise
real cert chains (trusted-bootstrap-ca + trusted-device,
untrusted-attacker-ca + untrusted-device) so the Verify path
exercises real x509 chain validation, not mocks.
docs/features.md
* SCEP env-vars table extended with the two new MTLS env vars
(CERTCTL_SCEP_PROFILE_<NAME>_MTLS_ENABLED,
CERTCTL_SCEP_PROFILE_<NAME>_MTLS_CLIENT_CA_TRUST_BUNDLE_PATH).
Closes the G-3 'env var defined in Go but never documented' gate.
docs/legacy-est-scep.md
* New 'mTLS sibling route (Phase 6.5, opt-in)' section covering
opt-in env vars, TLS server config (union pool +
VerifyClientCertIfGiven), handler-layer per-profile gate,
full auth chain on /scep-mtls/<pathID>, operator migration
workflow from challenge-password-only to challenge+mTLS.
cowork/CLAUDE.md::Active Focus
* 'HALF 1 COMPLETE' updated from '(Phases 0-5 of 14 SHIPPED)' to
'(Phases 0-6 + Phase 6.5 of 14 SHIPPED)'.
Verification:
* gofmt + go vet + staticcheck clean across api/handler /
api/router / config / cmd/server.
* go test -short -count=1 green across api/handler (with the new
scep_mtls_test.go) / api/router / service / config / pkcs7 /
cmd/server / connector/issuer/local.
* G-3 docs-drift CI guard local check: empty in both directions
after the new MTLS env vars landed in features.md.
* The constitutional test ('can an operator flip the bit and
observe the behavior change end-to-end?') is YES: setting
CERTCTL_SCEP_PROFILE_<NAME>_MTLS_ENABLED=true plus the trust
bundle path produces a working /scep-mtls/<pathID> endpoint
that accepts trusted client certs + rejects untrusted ones,
with no further code changes required.
Phase 6.5 of 14 in SCEP RFC 8894 + Intune master bundle.
Half 1 (Phases 0-6 + 6.5) is now FEATURE-COMPLETE for the
ChromeOS / general-MDM use case. Half 2 (Phases 7-12) adds the
Microsoft Intune dynamic-challenge layer.