Add pvebc tool for parsing and verifying EBC Add-Secret-Request structures
Introduce pvebc, a CLI tool that parses and verifies the integrity of
Add-Secret-Request (ASR) structures used in Early Boot Customization for
SEL guests.
The tool processes an integrity-protected ASR structure consisting of:
- toc.asr: Meta secret that links to toc.pol via relative filepath and
SHA512 hash, integrity-protected by its AES GCM authentication tag
- toc.pol: Policy file containing AES GCM authentication tags (last 16
bytes) of all user-provided ASRs
- User ASRs: Individual Add-Secret-Requests containing encrypted secrets
This structure guarantees:
- Prevents ASR removal: toc.pol lists all expected ASR authentication tags
- Prevents ASR insertion: Unlisted ASRs are rejected
- Prevents ASR modification: AES GCM authentication tags provide
cryptographic integrity
- Prevents toc.pol tampering: toc.asr's integrity protection secures the
link
The tool verifies completeness by checking that all ASRs listed in toc.pol
are present and their AES GCM authentication tags match. This prevents
attackers from removing, inserting, or modifying ASRs during transport over
unsecured channels.
After verification, pvebc adds all ASRs to the Ultravisor (UV), which
decrypts them using the guest's secret key and makes them available to
the guest during early boot.
Assisted-by: IBM Bob:1.0.1
Acked-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Finn Callies <fcallies@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
