more dos protection (#8104)

ethcore/vm/src/schedule.rs

@@ -135,6 +135,10 @@ pub struct WasmCosts {
 	pub initial_mem: u32,
 	/// Grow memory cost, per page (64kb)
 	pub grow_mem: u32,
+	/// Memory copy cost, per byte
+	pub memcpy: u32,
+	/// Max stack height (native WebAssembly stack limiter)
+	pub max_stack_height: u32,
 	/// Cost of wasm opcode is calculated as TABLE_ENTRY_COST * `opcodes_mul` / `opcodes_div`
 	pub opcodes_mul: u32,
 	/// Cost of wasm opcode is calculated as TABLE_ENTRY_COST * `opcodes_mul` / `opcodes_div`
@@ -153,6 +157,8 @@ impl Default for WasmCosts {
 			static_address: 40,
 			initial_mem: 4096,
 			grow_mem: 8192,
+			memcpy: 1,
+			max_stack_height: 64*1024,
 			opcodes_mul: 3,
 			opcodes_div: 8,
 		}

ethcore/wasm/src/lib.rs

@@ -66,6 +66,12 @@ impl From<runtime::Error> for vm::Error {
 	}
 }
 
+enum ExecutionOutcome {
+	Suicide,
+	Return,
+	NotSpecial,
+}
+
 impl vm::Vm for WasmInterpreter {
 
 	fn exec(&mut self, params: ActionParams, ext: &mut vm::Ext) -> vm::Result<GasLeft> {
@@ -117,31 +123,25 @@ impl vm::Vm for WasmInterpreter {
 
 			let module_instance = module_instance.run_start(&mut runtime).map_err(Error)?;
 
-			match module_instance.invoke_export("call", &[], &mut runtime) {
-				Ok(_) => { },
-				Err(InterpreterError::Host(boxed)) => {
-					match boxed.downcast_ref::<runtime::Error>() {
-						None => {
-							return Err(vm::Error::Wasm("Invalid user error used in interpreter".to_owned()));
-						}
-						Some(runtime_err) => {
-							match *runtime_err {
-								runtime::Error::Suicide => {
-									// Suicide uses trap to break execution
-								}
-								ref any_err => {
-									trace!(target: "wasm", "Error executing contract: {:?}", boxed);
-									return Err(vm::Error::from(Error::from(InterpreterError::Host(Box::new(any_err.clone())))));
-								}
-							}
-						}
-					}
-				},
-				Err(err) => {
-					trace!(target: "wasm", "Error executing contract: {:?}", err);
-					return Err(vm::Error::from(Error::from(err)))
+			let invoke_result = module_instance.invoke_export("call", &[], &mut runtime);
+
+			let mut execution_outcome = ExecutionOutcome::NotSpecial;
+			if let Err(InterpreterError::Host(ref boxed)) = invoke_result {
+				let ref runtime_err = boxed.downcast_ref::<runtime::Error>()
+					.expect("Host errors other than runtime::Error never produced; qed");
+
+				match **runtime_err {
+					runtime::Error::Suicide => { execution_outcome = ExecutionOutcome::Suicide; },
+					runtime::Error::Return => { execution_outcome = ExecutionOutcome::Return; },
+					_ => {}
 				}
 			}
+
+			if let (ExecutionOutcome::NotSpecial, Err(e)) = (execution_outcome, invoke_result) {
+				trace!(target: "wasm", "Error executing contract: {:?}", e);
+				return Err(vm::Error::from(Error::from(e)));
+			}
+
 			(
 				runtime.gas_left().expect("Cannot fail since it was not updated since last charge"),
 				runtime.into_result(),

ethcore/wasm/src/runtime.rs

@@ -52,6 +52,8 @@ pub enum Error {
 	MemoryAccessViolation,
 	/// Native code resulted in suicide
 	Suicide,
+	/// Native code requested execution to finish
+	Return,
 	/// Suicide was requested but coudn't complete
 	SuicideAbort,
 	/// Invalid gas state inside interpreter
@@ -98,6 +100,7 @@ impl ::std::fmt::Display for Error {
 			Error::InvalidGasState => write!(f, "Invalid gas state"),
 			Error::BalanceQueryError => write!(f, "Balance query resulted in an error"),
 			Error::Suicide => write!(f, "Suicide result"),
+			Error::Return => write!(f, "Return result"),
 			Error::Unknown => write!(f, "Unknown runtime function invoked"),
 			Error::AllocationFailed => write!(f, "Memory allocation failed (OOM)"),
 			Error::BadUtf8 => write!(f, "String encoding is bad utf-8 sequence"),
@@ -273,7 +276,7 @@ impl<'a> Runtime<'a> {
 
 		self.result = self.memory.get(ptr, len as usize)?;
 
-		Ok(())
+		Err(Error::Return)
 	}
 
 	/// Destroy the runtime, returning currently recorded result of the execution.
@@ -305,6 +308,10 @@ impl<'a> Runtime<'a> {
 	/// Write input bytes to the memory location using the passed pointer
 	fn fetch_input(&mut self, args: RuntimeArgs) -> Result<()> {
 		let ptr: u32 = args.nth(0)?;
+
+		let args_len = self.args.len() as u64;
+		self.charge(|s| args_len * s.wasm().memcpy as u64)?;
+
 		self.memory.set(ptr, &self.args[..])?;
 		Ok(())
 	}
@@ -525,8 +532,8 @@ impl<'a> Runtime<'a> {
 	fn debug(&mut self, args: RuntimeArgs) -> Result<()>
 	{
 		trace!(target: "wasm", "Contract debug message: {}", {
-			let msg_ptr: u32 = args.nth_checked(0)?;
-			let msg_len: u32 = args.nth_checked(1)?;
+			let msg_ptr: u32 = args.nth(0)?;
+			let msg_len: u32 = args.nth(1)?;
 
 			String::from_utf8(self.memory.get(msg_ptr, msg_len as usize)?)
 				.map_err(|_| Error::BadUtf8)?

ethcore/wasm/src/tests.rs

@@ -209,7 +209,7 @@ fn dispersion() {
 		result,
 		vec![0u8, 0, 125, 11, 197, 7, 255, 8, 19, 0]
 	);
-	assert_eq!(gas_left, U256::from(93_972));
+	assert_eq!(gas_left, U256::from(94_013));
 }
 
 #[test]
@@ -237,7 +237,7 @@ fn suicide_not() {
 		result,
 		vec![0u8]
 	);
-	assert_eq!(gas_left, U256::from(94_970));
+	assert_eq!(gas_left, U256::from(94_984));
 }
 
 #[test]
@@ -269,7 +269,7 @@ fn suicide() {
 	};
 
 	assert!(ext.suicides.contains(&refund));
-	assert_eq!(gas_left, U256::from(94_933));
+	assert_eq!(gas_left, U256::from(94_925));
 }
 
 #[test]
@@ -299,15 +299,15 @@ fn create() {
 	assert!(ext.calls.contains(
 		&FakeCall {
 			call_type: FakeCallType::Create,
-			gas: U256::from(60_917),
+			gas: U256::from(60_914),
 			sender_address: None,
 			receive_address: None,
 			value: Some(1_000_000_000.into()),
 			data: vec![0u8, 2, 4, 8, 16, 32, 64, 128],
 			code_address: None,
 		}
 	));
-	assert_eq!(gas_left, U256::from(60_903));
+	assert_eq!(gas_left, U256::from(60_900));
 }
 
 #[test]
@@ -467,7 +467,7 @@ fn realloc() {
 		}
 	};
 	assert_eq!(result, vec![0u8; 2]);
-	assert_eq!(gas_left, U256::from(94_352));
+	assert_eq!(gas_left, U256::from(94_372));
 }
 
 #[test]
@@ -543,7 +543,7 @@ fn keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(84_223));
+	assert_eq!(gas_left, U256::from(84_240));
 }
 
 // math_* tests check the ability of wasm contract to perform big integer operations
@@ -572,7 +572,7 @@ fn math_add() {
 		U256::from_dec_str("1888888888888888888888888888887").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(93_818));
+	assert_eq!(gas_left, U256::from(93_814));
 }
 
 // multiplication
@@ -594,7 +594,7 @@ fn math_mul() {
 		U256::from_dec_str("888888888888888888888888888887111111111111111111111111111112").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(93_304));
+	assert_eq!(gas_left, U256::from(93_300));
 }
 
 // subtraction
@@ -616,7 +616,7 @@ fn math_sub() {
 		U256::from_dec_str("111111111111111111111111111111").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(93_831));
+	assert_eq!(gas_left, U256::from(93_826));
 }
 
 // subtraction with overflow
@@ -658,7 +658,7 @@ fn math_div() {
 		U256::from_dec_str("1125000").unwrap(),
 		(&result[..]).into()
 	);
-	assert_eq!(gas_left, U256::from(90_607));
+	assert_eq!(gas_left, U256::from(90_603));
 }
 
 #[test]
@@ -686,7 +686,7 @@ fn storage_metering() {
 	};
 
 	// 0 -> not 0
-	assert_eq!(gas_left, U256::from(74_410));
+	assert_eq!(gas_left, U256::from(74_338));
 
 	// #2
 
@@ -705,7 +705,7 @@ fn storage_metering() {
 	};
 
 	// not 0 -> not 0
-	assert_eq!(gas_left, U256::from(89_410));
+	assert_eq!(gas_left, U256::from(89_338));
 }
 
 // This test checks the ability of wasm contract to invoke
@@ -793,7 +793,7 @@ fn externs() {
 		"Gas limit requested and returned does not match"
 	);
 
-	assert_eq!(gas_left, U256::from(92_089));
+	assert_eq!(gas_left, U256::from(92_110));
 }
 
 #[test]
@@ -819,7 +819,7 @@ fn embedded_keccak() {
 	};
 
 	assert_eq!(H256::from_slice(&result), H256::from("68371d7e884c168ae2022c82bd837d51837718a7f7dfb7aa3f753074a35e1d87"));
-	assert_eq!(gas_left, U256::from(84_223));
+	assert_eq!(gas_left, U256::from(84_240));
 }
 
 /// This test checks the correctness of log extern
@@ -854,5 +854,5 @@ fn events() {
 	assert_eq!(&log_entry.data, b"gnihtemos");
 
 	assert_eq!(&result, b"gnihtemos");
-	assert_eq!(gas_left, U256::from(81_235));
+	assert_eq!(gas_left, U256::from(81_292));
 }