Implement cumulus StorageWeightReclaim as wrapping transaction extension + frame system ReclaimWeight

[gui1117]

(rebasing of #5234)

Issues:

• Transaction extensions have weights and refund weight. So the reclaiming of unused weight must happen last in the transaction extension pipeline. Currently it is inside CheckWeight.
• cumulus storage weight reclaim transaction extension misses the proof size of logic happening prior to itself.

Done:

• a new storage ExtrinsicWeightReclaimed in frame-system. Any logic which attempts to do some reclaim must use this storage to avoid double reclaim.

• a new function reclaim_weight in frame-system pallet: info and post info in arguments, read the already reclaimed weight, calculate the new unused weight from info and post info. do the more accurate reclaim if higher.

• CheckWeight is unchanged and still reclaim the weight in post dispatch

• ReclaimWeight is a new transaction extension in frame system. For solo chains it must be used last in the transactino extension pipeline. It does the final most accurate reclaim

• StorageWeightReclaim is moved from cumulus primitives into its own pallet (in order to define benchmark) and is changed into a wrapping transaction extension.
  It does the recording of proof size and does the reclaim using this recording and the info and post info. So parachains don't need to use ReclaimWeight. But also if they use it, there is no bug.

  /// The TransactionExtension to the basic transaction logic.
  pub type TxExtension = cumulus_pallet_weight_reclaim::StorageWeightReclaim<
       Runtime,
       (
               frame_system::CheckNonZeroSender<Runtime>,
               frame_system::CheckSpecVersion<Runtime>,
               frame_system::CheckTxVersion<Runtime>,
               frame_system::CheckGenesis<Runtime>,
               frame_system::CheckEra<Runtime>,
               frame_system::CheckNonce<Runtime>,
               frame_system::CheckWeight<Runtime>,
               pallet_transaction_payment::ChargeTransactionPayment<Runtime>,
               BridgeRejectObsoleteHeadersAndMessages,
               (bridge_to_rococo_config::OnBridgeHubWestendRefundBridgeHubRococoMessages,),
               frame_metadata_hash_extension::CheckMetadataHash<Runtime>,
       ),
  >;

[bkchr]

Anyway this doesn't have any vulnerability, it just wastes resources, but people should put the CheckWeight last in the pipeline.

I would say it depends. When you are required to put CheckWeight as the latest extension, it also means that you are missing a cheap, early return.

[georgepisaltu]

you are missing a cheap, early return

Going through the pipeline should be cheap anyway. It's just extensions which are pretty light and the "wasted" work for overweight transactions should be done off-chain when validators are building their blocks.

Because the weight check isn't hardcoded and users can build whatever extension they like to handle it, we need to have some sort of convention when we introduce other weight related logic. I skimmed through the PR and I like the approach, but I won't formally approve because I didn't review thoroughly.

[gui1117]

Anyway this doesn't have any vulnerability, it just wastes resources, but people should put the CheckWeight last in the pipeline.

I would say it depends. When you are required to put CheckWeight as the latest extension, it also means that you are missing a cheap, early return.

Maybe it is time to split this transaction extension into CheckWeight and RefundWeight.

EDIT: or we can do the RefundWeight in note_applied_extrinsic.

EDIT: or we can use a storage to store the weight refunded by CheckWeight, then StorageWeightReclaim will just take this value instead of trying to guess it incorrectly.

EDIT: I decided to with a new storage ExtrinsicWeight or ExtrinsicWeightRefunded, CheckWeight will register its refund there, then StorageWeightReclaim will undo the CheckWeight operation and do the correct refund.

Later we can introduce another RefundWeight for solo-chains or parachains that doesn't want to use StorageWeightReclaim. RefundWeight can be placed at the end of the pipeline, and CheckWeight is unchanged and not breaking.

[gui1117]

thanks @skunert , comments should addressed.