runtime-sdk/modules/evm: Revert "drop signed queries in new contracts"

Given further thought this seems too much like a foot gun.

runtime-sdk/modules/evm/src/backend.rs

@@ -550,15 +550,6 @@ impl<'ctx, 'backend, 'config, C: TxContext, Cfg: Config> StackState<'config>
             let mut store = state::codes(store);
             store.insert(address, code);
         });
-
-        // Set metadata for newly created contracts.
-        state::set_metadata(
-            &address.into(),
-            types::ContractMetadata {
-                // For all new contracts we don't zeroize the caller in queries.
-                features: types::FeatureMask::QUERIES_NO_CALLER_ZEROIZE,
-            },
-        );
     }
 
     fn transfer(&mut self, transfer: Transfer) -> Result<(), ExitError> {

runtime-sdk/modules/evm/src/lib.rs

@@ -39,7 +39,7 @@ use oasis_runtime_sdk::{
     },
 };
 
-use types::{FeatureMask, H160, H256, U256};
+use types::{H160, H256, U256};
 
 #[cfg(any(test, feature = "test"))]
 pub mod mock;
@@ -617,22 +617,13 @@ impl<Cfg: Config> Module<Cfg> {
             ));
         }
 
-        // Determine the caller based on per-contract features.
-        let caller = if state::get_metadata(&call.address)
-            .has_features(FeatureMask::QUERIES_NO_CALLER_ZEROIZE)
-        {
-            call.caller
-        } else {
-            Default::default() // Zeroize caller.
-        };
-
         // The call is not signed, but it must be encoded as an oasis-sdk call.
         let tx_call_format = transaction::CallFormat::Plain; // Queries cannot be encrypted.
         let (data, tx_metadata) = Self::decode_call_data(ctx, call.data, tx_call_format, 0, true)?
             .expect("processing always proceeds");
         Ok((
             types::SimulateCallQuery {
-                caller,
+                caller: Default::default(), // The sender cannot be spoofed.
                 data,
                 ..call
             },

runtime-sdk/modules/evm/src/state.rs

@@ -3,10 +3,7 @@ use oasis_runtime_sdk::{
     storage::{ConfidentialStore, CurrentStore, HashedStore, PrefixStore, Store, TypedStore},
 };
 
-use crate::{
-    types::{ContractMetadata, H160},
-    Config,
-};
+use crate::{types::H160, Config};
 
 /// Prefix for Ethereum account code in our storage (maps H160 -> Vec<u8>).
 pub const CODES: &[u8] = &[0x01];
@@ -17,8 +14,6 @@ pub const STORAGES: &[u8] = &[0x02];
 pub const BLOCK_HASHES: &[u8] = &[0x03];
 /// Prefix for Ethereum account storage in our confidential storage (maps H160||H256 -> H256).
 pub const CONFIDENTIAL_STORAGES: &[u8] = &[0x04];
-/// Prefix for contract metadata (maps H160 -> ContractMetadata).
-pub const METADATA: &[u8] = &[0x05];
 
 /// Confidential store key pair ID domain separation context base.
 pub const CONFIDENTIAL_STORE_KEY_PAIR_ID_CONTEXT_BASE: &[u8] = b"oasis-runtime-sdk/evm: state";
@@ -123,21 +118,3 @@ pub fn block_hashes<'a, S: Store + 'a>(state: S) -> TypedStore<impl Store + 'a>
     let store = PrefixStore::new(state, &crate::MODULE_NAME);
     TypedStore::new(PrefixStore::new(store, &BLOCK_HASHES))
 }
-
-/// Set contract metadata.
-pub fn set_metadata(address: &H160, metadata: ContractMetadata) {
-    CurrentStore::with(|store| {
-        let store = PrefixStore::new(store, &crate::MODULE_NAME);
-        let mut store = TypedStore::new(PrefixStore::new(store, &METADATA));
-        store.insert(address, metadata);
-    })
-}
-
-/// Get contract metadata.
-pub fn get_metadata(address: &H160) -> ContractMetadata {
-    CurrentStore::with(|store| {
-        let store = PrefixStore::new(store, &crate::MODULE_NAME);
-        let store = TypedStore::new(PrefixStore::new(store, &METADATA));
-        store.get(address).unwrap_or_default()
-    })
-}

runtime-sdk/modules/evm/src/test.rs

@@ -832,11 +832,7 @@ fn test_c10l_queries() {
         ethabi::decode(&[ParamType::Address], &result).expect("output should be correct");
 
     let test = result.pop().unwrap().into_address().unwrap();
-    assert_eq!(
-        test,
-        signer.address().into(),
-        "msg.signer should be correct (non-zeroized)"
-    );
+    assert_eq!(test, Default::default(), "msg.signer should be zeroized");
 
     // Test call with confidential envelope.
     let result = signer
@@ -856,24 +852,6 @@ fn test_c10l_queries() {
     let mut result =
         ethabi::decode(&[ParamType::Address], &result).expect("output should be correct");
 
-    let test = result.pop().unwrap().into_address().unwrap();
-    assert_eq!(
-        test,
-        signer.address().into(),
-        "msg.signer should be correct (non-zeroized)"
-    );
-
-    // Reset the contract metadata to remove the QUERIES_NO_CALLER_ZEROIZE feature.
-    state::set_metadata(&contract_address, Default::default());
-
-    // Call the `test` method again on the contract via a query.
-    let result = signer
-        .query_evm(&mut ctx, contract_address, "test", &[], &[])
-        .expect("query should succeed");
-
-    let mut result =
-        ethabi::decode(&[ParamType::Address], &result).expect("output should be correct");
-
     let test = result.pop().unwrap().into_address().unwrap();
     assert_eq!(test, Default::default(), "msg.signer should be zeroized");
 }

runtime-sdk/modules/evm/src/types.rs

@@ -102,46 +102,6 @@ pub struct Leash {
     pub block_range: u64,
 }
 
-/// Features affecting a contract's behavior.
-#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, cbor::Encode, cbor::Decode)]
-#[cbor(transparent)]
-pub struct FeatureMask(pub u32);
-
-impl FeatureMask {
-    /// Caller should never be zeroized in queries.
-    pub const QUERIES_NO_CALLER_ZEROIZE: FeatureMask = FeatureMask(1 << 0);
-}
-
-impl std::ops::BitOr for FeatureMask {
-    type Output = Self;
-
-    fn bitor(self, rhs: Self) -> Self::Output {
-        Self(self.0 | rhs.0)
-    }
-}
-
-impl std::ops::BitAnd for FeatureMask {
-    type Output = Self;
-
-    fn bitand(self, rhs: Self) -> Self::Output {
-        Self(self.0 & rhs.0)
-    }
-}
-
-/// Contract metadata.
-#[derive(Clone, Debug, Default, cbor::Encode, cbor::Decode)]
-pub struct ContractMetadata {
-    /// Features supported by the contract.
-    pub features: FeatureMask,
-}
-
-impl ContractMetadata {
-    /// Check whether the contract has the specified features.
-    pub fn has_features(&self, mask: FeatureMask) -> bool {
-        self.features & mask == mask
-    }
-}
-
 // The rest of the file contains wrappers for primitive_types::{H160, H256, U256},
 // so that we can implement cbor::{Encode, Decode} for them, ugh.
 // Remove this once oasis-cbor#8 is implemented.
@@ -259,24 +219,3 @@ mod eth {
     impl_upstream_conversions!(H160, H256, U256);
 }
 pub use eth::{H160, H256, U256};
-
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn test_contract_metadata() {
-        let meta = ContractMetadata::default();
-        assert!(!meta.has_features(FeatureMask::QUERIES_NO_CALLER_ZEROIZE));
-
-        let meta = ContractMetadata {
-            features: FeatureMask::QUERIES_NO_CALLER_ZEROIZE,
-        };
-        assert!(meta.has_features(FeatureMask::QUERIES_NO_CALLER_ZEROIZE));
-
-        let meta = ContractMetadata {
-            features: FeatureMask(0xff),
-        };
-        assert!(meta.has_features(FeatureMask::QUERIES_NO_CALLER_ZEROIZE));
-    }
-}