fix(triage): fetch tag-based attestation via oras; support cosign 3.x output#113
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retrieve-triage reported every JFrog image as having no triage when run with
cosign 3.x. Two issues, both in the tag-based path:
1. cosign 3.x changed `download attestation` output from a bare DSSE envelope
({"payload": <b64>}) to a sigstore bundle ({"dsseEnvelope": {"payload": <b64>}}).
The parser only read the top-level `payload`, so it found no triage predicate
even though cosign returned the attestation. cosign 2.x still emits the old
shape — the result silently depended on the installed cosign version.
2. Relying on `cosign download attestation` at all couples the result to the
local cosign version.
Fix: fetch the `sha256-<digest>.att` manifest directly with oras and decode its
DSSE layers newest-first, stopping at the first triage match (one blob fetch for
the common re-attested case). This is cosign-version-independent; oras/crane are
already prerequisites and use plain registry reads JFrog supports (the .att tag,
not the Referrers API). Keep `cosign download attestation` as a fallback, now
parsing both the bare-envelope and bundle shapes.
Verified with cosign v3.0.5 (the reported version), v2.4.2, and a stubbed cosign
returning nothing: 41/41 fetched via the oras .att path in all cases. The
newest-first scan cuts oras blob fetches 390 -> 41 over the 41-image list (~10m
-> ~3m) and produces byte-identical triage files and report vs scanning all
layers.
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Problem
Run with cosign 3.x,
retrieve-triagereports every JFrog image as having no triage — even ones that clearly have it:Confirmed root cause (reproduced with cosign v3.0.5 vs v2.4.2): cosign 3.x changed the
download attestationoutput format. It still returns all attestations (verified: 9 incl. the triage predicate), but as a sigstore bundle — the DSSE payload moved from top-levelpayloadtodsseEnvelope.payload:download attestationline shape{"payload": <b64>, "signatures": […]}.payload){"mediaType": ".../bundle.v0.3+json", "dsseEnvelope": {"payload": <b64>}}.payload)So the result silently depended on the installed cosign version. (It is not the Referrers API — JFrog lacks Referrers discovery, but the
.attis a plain tag that pulls fine.)Change
sha256-<digest>.attmanifest directly with oras and decode its DSSE layers newest-first, stopping at the first triage match (one blob fetch for the common re-attested case). cosign-version-independent; plain registry reads JFrog supports.cosign download attestation, now parsing both the bare-DSSE-envelope (.payload) and sigstore-bundle (.dsseEnvelope.payload) shapes.Verification
.att, 0 via cosign, 0 skips; report = 25 sections / 158 CVE rows, headers remapped to JFrog refs..att.diff -rqconfirms the triage files and report are byte-identical to scanning all layers.Works regardless of the installed cosign version.