Robert Allan JamesandClaude Sonnet 5
2fc55f47e1
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
27 lines
1.2 KiB
C
27 lines
1.2 KiB
C
/*
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* pkcs8_ed25519.h -- extract the raw 32-byte Ed25519 seed from a
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* PKCS#8 DER-encoded private key (RFC 8410 OneAsymmetricKey), for
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* mkcapsule's host-side capsule signing step (Milestone 6, Phase 8).
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*
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* Host-only: this never runs in the kernel (the kernel never signs, see
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* ed25519.h). Deliberately its own narrow, from-scratch DER walker, not
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* shared with src/starkernel/crypto/x509_ed25519.c -- that file walks a
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* full Certificate structure to a *public* key; this one walks the much
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* smaller PKCS#8 OneAsymmetricKey structure to a *private* key seed.
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* Small enough that duplicating the handful of TLV-walking lines is
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* simpler and easier to audit independently than threading a shared
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* header between the kernel crypto tree and host build tooling.
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*/
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#ifndef TOOLS_PKCS8_ED25519_H
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#define TOOLS_PKCS8_ED25519_H
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#include <stdint.h>
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#include <stddef.h>
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/* Returns 0 on success (seed_out[32] filled), -1 on any malformed
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* encoding or non-Ed25519 algorithm. Never faults on malformed input. */
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int pkcs8_extract_ed25519_seed(const uint8_t *der, size_t der_len,
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uint8_t seed_out[32]);
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#endif /* TOOLS_PKCS8_ED25519_H */
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