After playing seriously with Rust's declrative macros for the first time instead of just using them I got pretty neat results. This is because I intend to keep tpm2_protocol depdency free so that it could be used in-kernel if that is ever feasible.

This is how I declare command bodies now in the implementation:

tpm_command!(
TpmStartAuthSessionCommand,
TpmCc::StartAuthSession,
TpmSt::NoSessions,
2,
pub nonce_caller: Tpm2b,
pub encrypted_salt: Tpm2b,
pub session_type: TpmSe,
pub symmetric: TpmtSymDefObject,
pub auth_hash: TpmAlgId,
);

[2 is in fact number handles]

This will generate the command and implement traits for marshalling AND unmarshalling command. Both are implemented in-depth for all TCG specification types across the board.

Another simpler example is TPML_* from the specification:

tpml!(TpmlAlgProperty, TpmsAlgProperty);
tpml!(TpmlDigest, Tpm2b);
tpml!(TpmlDigestValues, TpmtHa);
tpml!(TpmlHandle, u32);
tpml!(TpmlPcrSelection, TpmsPcrSelection);

And TPM2B_*:

tpm2b!(full; Tpm2bAttest, TpmsAttest);
tpm2b!(full; Tpm2bContextData, TpmsContextData);
tpm2b!(full; Tpm2bCreationData, TpmsCreationData);
tpm2b!(full; Tpm2bEccPoint, TpmsEccPoint);
tpm2b!(full; Tpm2bEncryptedSecret, TpmuEncryptedSecret);
tpm2b!(full; Tpm2bIdObject, TpmsIdObject);
tpm2b!(full; Tpm2bNvPublic, TpmsNvPublic);
tpm2b!(full; Tpm2bSensitive, TpmtSensitive);
tpm2b!(full; Tpm2bTemplate, TpmtPublic);

I find this really fascinating :-)

#rust #rustlang #linux #kernel #tpm

SLOC went over 6k before I migrated into extensive macro usage :-)

My goal for full TCG is ~5k SLOC.