Closes the contributor-capsule/trust-tier punch-list item. Decided
direction: QEMU-vs-real-hardware conditional enforcement.
Found before building on that decision: the obvious mechanism (expose
TimerInfo.vm_mode) only works on amd64 -- aarch64 and riscv64 both had
vm_mode hardcoded to 1 unconditionally, meaning they'd always report
"running under QEMU" even on real hardware. Built real detection for
both instead of shipping that: aarch64 checks the ACPI RSDP's OEM ID
for QEMU's "BOCHS " SeaBIOS-heritage signature; riscv64 checks the
devicetree root compatible property for "qemu". Confirmed vm_mode was
otherwise unread anywhere else in either file first -- zero risk to
existing timing behavior.
CAPSULE_FLAG_CONTRIB (mkcapsule.c: FLAG_CONTRIB) path-matches on
capsules/contrib/, mirroring FLAG_MAMA_INIT's exact-match pattern.
contrib_capsule_refused() (capsule_birth.c) enforces: no additional
check under QEMU (same WARN-only as everything else); on real hardware,
a contrib capsule additionally requires CAPSULE_SIG_OK, since it has no
other provenance to fall back on. Wired into capsule_birth_baby() and
capsule_run_experiment().
Also updates §I.7 (Milestone 9): its stated precondition (Milestone 7
closing) is now met, flagged as stale rather than treated as a green
light to design networking from nothing.
Verified 3-arch boot to ok> (amd64/aarch64/riscv64, each in the
foreground) -- compile/boot verification only; the real-hardware
enforcement branch is unverifiable from this environment, same as all
of §I.6. logs and DoE CSVs from this session's verification runs
included per this repo's own audit-artifact convention.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019YcT3H2PQeyujrzjqS3Var
First attempt shelled out to `openssl pkeyutl -sign` (fork/execlp, not
system() -- avoided shell string interpolation of the key path).
Corrected on request: no new external host binary dependency when the
repo's own code can do the job -- same standing preference as the
earlier anti-file correction. Rewritten to link ed25519_sign() (already
verified against OpenSSL in Phase B) directly into mkcapsule.
New tools/pkcs8_ed25519.c: a narrow DER walker (same shape as
x509_ed25519.c, deliberately not shared -- small enough that
duplicating a few TLV-walking lines beat threading a header between the
kernel crypto tree and host tooling) extracting the raw seed from the
intermediate's PKCS#8 private key, plus a minimal self-written base64
decoder (PEM is openssl genpkey's default output; no decoder existed
anywhere in the repo). Verified end-to-end before wiring anything in:
the extracted seed's derived pubkey matches the cert's exactly, and a
full self-contained sign+verify round-trip (zero openssl) passes.
CapsuleDesc had no spare bytes, so signatures live in a new parallel
CapsuleSigEntry array, emitted by a new `mkcapsule --sign-key <path>`
flag (omitted/missing key -> has_sig=0 everywhere, graceful, not a
build failure -- CI has no access to the offline key).
New capsule_sig.c/.h: capsule_verify_signature(), a separate function,
not folded into the already-tested capsule_validate(). Finds and caches
the embedded intermediate cert's pubkey once per boot, then verifies
against it. Wired into all three capsule_validate() call sites in
capsule_birth.c via log_message(LOG_WARN, ...) -- never refuses yet,
per the earlier staged-rollout decision.
Verified independently, both directions, live in the real kernel: a
full clean build (38 signed capsules) boots clean on all three
architectures with zero warnings. Separately, hand-corrupted one byte
of Mama's own init.4th capsule's stored signature (not its payload/hash,
which capsule_validate() already catches and would have masked the
test) and rebuilt just the changed object: produced exactly "capsule
sig: init.4th: INVALID -- signature does not verify" on boot, and the
kernel still reached ok> -- proving warn-only doesn't refuse anything
yet. Reverted before the final, untampered 3-arch acceptance pass.
Still open: flipping WARN to hard-refuse (separate, deliberate step)
and the BLOCK_MAP.md signature-status column. Documented in FABRIC-3.md.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01U14ET9CWAtbQMbYqomKgXd
