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Alternate handover batch TOCTOU fix (#397)

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* Revert "Correct the prior documented TOCTOU"

This reverts commit d50fe87801.

* Correct the prior documented TOCTOU

d50fe87801 edited the challenge for the Batch to
fix it. This won't produce Batch n+1 until Batch n is successfully published
and verified. It's an alternative strategy able to be reviewed, with a much
smaller impact to scope.
This commit is contained in:
Luke Parker
2023-10-13 12:14:59 -04:00
committed by GitHub
parent 7d0d1dc382
commit f6e8bc3352
9 changed files with 144 additions and 78 deletions
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24
processor/src/substrate_signer.rs
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@@ -52,18 +52,6 @@ impl<D: Db> SubstrateSignerDb<D> {
D::key(b"SUBSTRATE_SIGNER", dst, key)
}
fn first_batch_key(key: [u8; 32]) -> Vec<u8> {
Self::sign_key(b"first_batch", key)
}
fn save_first_batch(txn: &mut D::Transaction<'_>, key: [u8; 32], id: u32) {
txn.put(Self::first_batch_key(key), id.to_le_bytes());
}
fn first_batch<G: Get>(getter: &G, key: [u8; 32]) -> Option<u32> {
getter
.get(Self::first_batch_key(key))
.map(|bytes| u32::from_le_bytes(bytes.try_into().unwrap()))
}
fn completed_key(id: [u8; 32]) -> Vec<u8> {
Self::sign_key(b"completed", id)
}
@@ -241,11 +229,6 @@ impl<D: Db> SubstrateSigner<D> {
return;
}
let group_key = self.keys.group_key().to_bytes();
if SubstrateSignerDb::<D>::first_batch(txn, group_key).is_none() {
SubstrateSignerDb::<D>::save_first_batch(txn, group_key, batch.id);
}
self.signable.insert(id, batch);
self.attempt(txn, id, 0).await;
}
@@ -287,13 +270,8 @@ impl<D: Db> SubstrateSigner<D> {
Err(e) => todo!("malicious signer: {:?}", e),
};
let batch = &self.signable[&id.id];
let is_first_batch =
SubstrateSignerDb::<D>::first_batch(txn, self.keys.group_key().to_bytes()).unwrap() ==
batch.id;
let (machine, share) =
match machine.sign(preprocesses, &batch_message(is_first_batch, batch)) {
match machine.sign(preprocesses, &batch_message(&self.signable[&id.id])) {
Ok(res) => res,
Err(e) => todo!("malicious signer: {:?}", e),
};