Companion for PR 8913 (#3114)

* Companion for PR 8913

polkadot companion: https://github.com/paritytech/substrate/pull/8913

* update Substrate

Co-authored-by: parity-processbot <>

polkadot/node/core/pvf/Cargo.toml

@@ -36,18 +36,3 @@ adder = { package = "test-parachain-adder", path = "../../../parachain/test-para
 halt = { package = "test-parachain-halt", path = "../../../parachain/test-parachains/halt" }
 hex-literal = "0.3.1"
 tempfile = "3.2.0"
-
-# PVF execution leverages compiled artifacts provided by wasmtime. The contents of the artifacts
-# depends on the version of wasmtime. In this crate we persist the artifacts on disk so we should
-# be careful about the updates. In order to handle this, we depend on the wasmtime version here
-# that we think is used by the sc-executor. If wasmtime is updated in Substrate and wasn't updated
-# here then there will be linking errors like
-#
-#     `multiple definitions of `set_vmctx_memory`.
-#
-# or similar, because wasmtime exports these symbols and does not support multiple versions compiled
-# in at the same time.
-#
-# Another safeguard is a test `ensure_wasmtime_version` that will fail on each bump and prompt the
-# developer to correspondingly act upon the change.
-wasmtime-jit = "0.24"

polkadot/node/core/pvf/src/artifacts.rs

@@ -60,7 +60,7 @@ pub struct ArtifactId {
 }
 
 impl ArtifactId {
-	const PREFIX: &'static str = "wasmtime_1_";
+	const PREFIX: &'static str = "wasmtime_";
 
 	/// Creates a new artifact ID with the given hash.
 	pub fn new(code_hash: Hash) -> Self {
@@ -191,19 +191,6 @@ mod tests {
 	use sp_core::H256;
 	use std::str::FromStr;
 
-	#[test]
-	fn ensure_wasmtime_version() {
-		assert_eq!(
-			wasmtime_jit::VERSION,
-			"0.24.0",
-			"wasmtime version is updated. Check the prefix.",
-		);
-		// If the version bump is significant, change `ArtifactId::PREFIX`.
-		//
-		// If in doubt bump it. This will lead to removal of the existing artifacts in the on-disk cache
-		// and recompilation.
-	}
-
 	#[test]
 	fn from_file_name() {
 		assert!(ArtifactId::from_file_name("").is_none());
@@ -211,7 +198,7 @@ mod tests {
 
 		assert_eq!(
 			ArtifactId::from_file_name(
-				"wasmtime_1_0x0022800000000000000000000000000000000000000000000000000000000000"
+				"wasmtime_0x0022800000000000000000000000000000000000000000000000000000000000"
 			),
 			Some(ArtifactId::new(
 				hex_literal::hex![
@@ -229,7 +216,7 @@ mod tests {
 
 		assert_eq!(
 			ArtifactId::new(hash).path(path).to_str(),
-			Some("/test/wasmtime_1_0x1234567890123456789012345678901234567890123456789012345678901234"),
+			Some("/test/wasmtime_0x1234567890123456789012345678901234567890123456789012345678901234"),
 		);
 	}
 
@@ -238,7 +225,7 @@ mod tests {
 		let fake_cache_path = async_std::task::block_on(async move { crate::worker_common::tmpfile("test-cache").await.unwrap() });
 		let fake_artifact_path = {
 			let mut p = fake_cache_path.clone();
-			p.push("wasmtime_1_0x1234567890123456789012345678901234567890123456789012345678901234");
+			p.push("wasmtime_0x1234567890123456789012345678901234567890123456789012345678901234");
 			p
 		};
 

polkadot/node/core/pvf/src/execute/worker.rs

@@ -246,7 +246,12 @@ async fn validate_using_artifact(
 
 	let validation_started_at = Instant::now();
 	let descriptor_bytes =
-		match crate::executor_intf::execute(compiled_artifact, params, spawner.clone()) {
+		match unsafe {
+			// SAFETY: this should be safe since the compiled artifact passed here comes from the
+			//         file created by the prepare workers. These files are obtained by calling
+			//         [`executor_intf::prepare`].
+			crate::executor_intf::execute(compiled_artifact, params, spawner.clone())
+		 } {
 			Err(err) => {
 				return Response::format_invalid("execute", &err.to_string());
 			}

polkadot/node/core/pvf/src/executor_intf.rs

@@ -56,7 +56,12 @@ pub fn prepare(blob: RuntimeBlob) -> Result<Vec<u8>, sc_executor_common::error::
 
 /// Executes the given PVF in the form of a compiled artifact and returns the result of execution
 /// upon success.
-pub fn execute(
+///
+/// # Safety
+///
+/// The compiled artifact must be produced with [`prepare`]. Not following this guidance can lead
+/// to arbitrary code execution.
+pub unsafe fn execute(
 	compiled_artifact: &[u8],
 	params: &[u8],
 	spawner: impl sp_core::traits::SpawnNamed + 'static,
@@ -69,8 +74,8 @@ pub fn execute(
 	let mut ext = ValidationExternalities(extensions);
 
 	sc_executor::with_externalities_safe(&mut ext, || {
-		let runtime = sc_executor_wasmtime::create_runtime(
+		let runtime = sc_executor_wasmtime::create_runtime_from_artifact(
-			sc_executor_wasmtime::CodeSupplyMode::Artifact { compiled_artifact },
+			compiled_artifact,
 			CONFIG,
 			HostFunctions::host_functions(),
 		)?;

polkadot/node/core/pvf/src/testing.rs

@@ -34,7 +34,10 @@ pub fn validate_candidate(
 	let blob = prevalidate(code)?;
 	let artifact = prepare(blob)?;
 	let executor = TaskExecutor::new()?;
-	let result = execute(&artifact, params, executor)?;
+	let result = unsafe {
+		// SAFETY: This is trivially safe since the artifact is obtained by calling `prepare`.
+		execute(&artifact, params, executor)?
+	};
 
 	Ok(result)
 }