[Ming-Wei Shih (mingweishih)]

Support external signing workflows for existing IGVM images without rebuilding them or substituting image identity defaults. Keep CoRIM endorsement preparation separate from SNP ID-block signing.

• Add prepare-endorsement and verify-endorsement for SNP, TDX, and VBS, with signing artifacts, hash provenance, and verification of the selected endorsement without permitting unrelated image changes.
• Add prepare-snp-id-block with an optional decoded JSON dump and add-snp-id-block --replace-existing for identity-preserving external signatures. Validate existing signatures or unsigned placeholders.
• Derive SNP endorsement SVN from an existing ID block, or require an explicit SVN when absent, as for TDX/VBS. Reject mismatches in both CoRIM preparation and ID-block addition or replacement.
• Allow explicit firmware DLL resource and language selection for inspection and finalized endorsement verification.
• Pin igvm and igvm_defs to upstream revision 568e2719972e, including checked SNP ID-block replacement from serializer: support checked SNP ID block replacement igvm#137.
• Document the independent signing workflows and trust boundaries in the igvmfilegen tool guide. Signature verification does not establish signer authorization or certificate trust.

Validation: igvmfilegen Clippy (all targets), rustdoc, all 96 unit tests, cargo xtask fmt --fix, and git diff --check passed. Hardware acceptance was not tested.

[Copilot]

🔵 Needs a closer look

Security-sensitive SNP re-signing and endorsement verification require human review of signer authorization and firmware assumptions, while hardware acceptance remains unvalidated.

No open issues 🎉

What changed in this PR

Extends igvmfilegen with external signing workflows for existing IGVM images, keeping CoRIM endorsement preparation separate from identity-preserving SNP ID-block signing.

Changes:

• Adds endorsement preparation and verification for SNP, TDX, and VBS, with artifact hashes and checks against unrelated image changes.
• Adds SNP signing-payload export and explicit ID-block replacement, including signature validation and guest SVN consistency checks.
• Adds firmware DLL resource selection, updates IGVM dependencies, and documents signing workflows and trust boundaries.

File	Description
vm/​loader/​igvmfilegen/​src/​snp_id_block.rs	Adds identity validation, payload export, signature replacement, and SVN checks with tests.
vm/​loader/​igvmfilegen/​src/​prepare_endorsement.rs	Implements endorsement preparation, artifact publication, and finalized-image verification with tests.
vm/​loader/​igvmfilegen/​src/​main.rs	Wires new commands and options into the CLI and adds command tests.
vm/​loader/​igvmfilegen/​src/​firmware_dll.rs	Adds explicit resource and language selection with ambiguity checks and tests.
vm/​loader/​igvmfilegen/​src/​corim_signature/​mod.rs	Exposes signature verification and test helpers for endorsement workflows.
vm/​loader/​igvmfilegen/​Cargo.toml	Adds tempfile for artifact publication.
Guide/​src/​dev_guide/​dev_tools/​igvmfilegen.md	Documents independent signing workflows, verification, resource selection, and trust limits.
Cargo.toml	Pins IGVM dependencies to the revision supporting checked ID-block replacement.
Cargo.lock	Records updated IGVM dependencies and the tool’s tempfile dependency.

_{Review effort: Balanced}

[github-actions]

1 Petri tests failed (0 unstable)