Claude
03027f9769
Ruled by Captain Bob, 2026-11-07: "New root CA on the CI box. Valid StarshipOS rather than snake oil intermediate." - ci/pki/make-ca.sh makes the StarshipOS Root CA (its key stays on the CI box) and the StarshipOS Capsule Signing intermediate it issues, and stores the signing key as the secret CAPSULE_SIGN_KEY. - The kernel finds the signing certificate by one name, CAPSULE_SIGNING_CERT_NAME = pki:starshipos-intermediate.der. The certificate itself lands once make-ca.sh has run; until then the snakeoil intermediate is in the tree under its old name and the capsules check as "no root key" (a warning, as "missing" was). - mkcapsule refuses a signing key that is not that certificate's. - SIGN_KEY has no default; acceptance, build, nightly and release set it from the secret. FABRIC-3.md XLVI. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01GE3SDvQn5EoxdGufk84zz2
59 lines
2.7 KiB
C
59 lines
2.7 KiB
C
/*
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* capsule_sig.h -- per-capsule Ed25519 signature verification
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* (Milestone 6, Phase 8). Deliberately kept separate from
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* capsule_validate.c: that function is already tested and its
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* signature/behavior stays untouched; this is a new, additive check
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* called alongside it, not folded into it.
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*
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* Enforced ONLY on CAPSULE_SIG_INVALID (2026-08-26, after landing
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* WARN-only and proving correct on all three architectures against both
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* a valid and a deliberately-corrupted capsule -- see FABRIC-2.md's
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* Milestone 6 writeup). CAPSULE_SIG_MISSING and CAPSULE_SIG_NO_ROOT_KEY
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* stay WARN-only, deliberately: MISSING is the normal state on every
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* machine without access to the offline signing key (CI, any other
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* checkout) -- refusing on it would brick boot everywhere but the one
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* machine that minted the key, not catch anything real. Only INVALID
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* (a signature that IS present but does not verify) is unambiguous
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* tampering/corruption evidence, safe to refuse on regardless of who's
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* building.
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*/
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#ifndef STARKERNEL_CAPSULE_SIG_H
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#define STARKERNEL_CAPSULE_SIG_H
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#include "starkernel/capsule.h"
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/* The certificate whose key the capsules are signed with: "StarshipOS
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* Capsule Signing", issued by the StarshipOS Root CA (ci/pki/make-ca.sh;
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* FABRIC-3.md XLVI), replacing the snakeoil intermediate of Milestone 6.
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* mkcapsule refuses to sign with a key that is not this certificate's. */
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#define CAPSULE_SIGNING_CERT_NAME "pki:starshipos-intermediate.der"
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typedef enum {
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CAPSULE_SIG_OK = 0, /* has_sig=1, and it verifies */
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CAPSULE_SIG_MISSING, /* has_sig=0 -- not signed at all */
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CAPSULE_SIG_INVALID, /* has_sig=1 but verification failed */
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CAPSULE_SIG_NO_ROOT_KEY, /* couldn't find/parse the embedded intermediate cert */
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} CapsuleSigResult;
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/*
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* Verify capsule descs[index]'s Ed25519 signature against the embedded
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* capsule-signing certificate's public key (CAPSULE_SIGNING_CERT_NAME,
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* found and parsed once, cached for every later call this boot -- the
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* cert doesn't change mid-boot).
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*
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* descs/names/sigs must be the same three parallel arrays
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* (capsule_get_descriptors()/capsule_get_names()/capsule_get_signatures()),
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* desc_count their shared length, arena_base the payload arena
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* (capsule_get_arena()). index must be < desc_count.
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*/
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CapsuleSigResult capsule_verify_signature(
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const CapsuleDesc *descs, const CapsuleNameEntry *names,
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const CapsuleSigEntry *sigs, const uint8_t *arena_base,
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uint32_t desc_count, int index);
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/* Human-readable string for logging, mirroring
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* capsule_validate_result_str()'s existing shape. */
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const char *capsule_sig_result_str(CapsuleSigResult result);
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#endif /* STARKERNEL_CAPSULE_SIG_H */
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