Implement static call (#991)

* Implement static call

* Refactor static call tests

* Reuse call's post for staticcall

* Change variable names and add docstring comments

* Rename variable name

* change the comment

* Fix the tests based on the merge

* Fix the tests

* Remove extra declaration of WriteProtection

* Fix static call test

* Add the missing condition in callcode

mythril/laser/ethereum/evm_exceptions.py

@@ -37,6 +37,12 @@ class OutOfGasException(VmException):
     pass
 
 
+class WriteProtection(VmException):
+    """A VM exception denoting that a write operation is executed on a write protected environment"""
+
+    pass
+
+
 class ProgramCounterException(VmException):
     """A VM exception denoting an invalid PC value (No stop instruction is reached)."""
 

mythril/laser/ethereum/instructions.py

@@ -38,6 +38,7 @@ from mythril.laser.ethereum.evm_exceptions import (
     InvalidJumpDestination,
     InvalidInstruction,
     OutOfGasException,
+    WriteProtection,
 )
 from mythril.laser.ethereum.gas import OPCODE_GAS
 from mythril.laser.ethereum.state.global_state import GlobalState
@@ -88,14 +89,18 @@ class StateTransition(object):
     if `increment_pc=True`.
     """
 
-    def __init__(self, increment_pc=True, enable_gas=True):
+    def __init__(
+        self, increment_pc=True, enable_gas=True, is_state_mutation_instruction=False
+    ):
         """
 
         :param increment_pc:
         :param enable_gas:
+        :param is_state_mutation_instruction: The function mutates state
         """
         self.increment_pc = increment_pc
         self.enable_gas = enable_gas
+        self.is_state_mutation_instruction = is_state_mutation_instruction
 
     @staticmethod
     def call_on_state_copy(func: Callable, func_obj: "Instruction", state: GlobalState):
@@ -165,6 +170,13 @@ class StateTransition(object):
             :param global_state:
             :return:
             """
+            if self.is_state_mutation_instruction and global_state.environment.static:
+                raise WriteProtection(
+                    "The function {} cannot be executed in a static call".format(
+                        func.__name__[:-1]
+                    )
+                )
+
             new_global_states = self.call_on_state_copy(func, func_obj, global_state)
             new_global_states = [
                 self.accumulate_gas(state) for state in new_global_states
@@ -1396,7 +1408,7 @@ class Instruction:
         state.stack.append(global_state.environment.active_account.storage[index])
         return [global_state]
 
-    @StateTransition()
+    @StateTransition(is_state_mutation_instruction=True)
     def sstore_(self, global_state: GlobalState) -> List[GlobalState]:
         """
 
@@ -1563,7 +1575,7 @@ class Instruction:
         global_state.mstate.stack.append(global_state.new_bitvec("gas", 256))
         return [global_state]
 
-    @StateTransition()
+    @StateTransition(is_state_mutation_instruction=True)
     def log_(self, global_state: GlobalState) -> List[GlobalState]:
         """
 
@@ -1578,7 +1590,7 @@ class Instruction:
         # Not supported
         return [global_state]
 
-    @StateTransition()
+    @StateTransition(is_state_mutation_instruction=True)
     def create_(self, global_state: GlobalState) -> List[GlobalState]:
         """
 
@@ -1586,13 +1598,14 @@ class Instruction:
         :return:
         """
         # TODO: implement me
+
         state = global_state.mstate
         state.stack.pop(), state.stack.pop(), state.stack.pop()
         # Not supported
         state.stack.append(0)
         return [global_state]
 
-    @StateTransition()
+    @StateTransition(is_state_mutation_instruction=True)
     def create2_(self, global_state: GlobalState) -> List[GlobalState]:
         """
 
@@ -1628,7 +1641,7 @@ class Instruction:
             return_data = state.memory[offset : offset + length]
         global_state.current_transaction.end(global_state, return_data)
 
-    @StateTransition()
+    @StateTransition(is_state_mutation_instruction=True)
     def suicide_(self, global_state: GlobalState):
         """
 
@@ -1733,6 +1746,21 @@ class Instruction:
             )
             return [global_state]
 
+        if environment.static:
+            if isinstance(value, int) and value > 0:
+                raise WriteProtection(
+                    "Cannot call with non zero value in a static call"
+                )
+            if isinstance(value, BitVec):
+                if value.symbolic:
+                    global_state.mstate.constraints.append(
+                        value == symbol_factory.BitVecVal(0, 256)
+                    )
+                elif value.value > 0:
+                    raise WriteProtection(
+                        "Cannot call with non zero value in a static call"
+                    )
+
         native_result = native_call(
             global_state, callee_address, call_data, memory_out_offset, memory_out_size
         )
@@ -1747,8 +1775,9 @@ class Instruction:
             callee_account=callee_account,
             call_data=call_data,
             call_value=value,
+            static=environment.static,
         )
-        raise TransactionStartSignal(transaction, self.op_code)
+        raise TransactionStartSignal(transaction, self.op_code, global_state)
 
     @StateTransition()
     def call_post(self, global_state: GlobalState) -> List[GlobalState]:
@@ -1757,65 +1786,8 @@ class Instruction:
         :param global_state:
         :return:
         """
-        instr = global_state.get_current_instruction()
-
-        try:
-            callee_address, callee_account, call_data, value, gas, memory_out_offset, memory_out_size = get_call_parameters(
-                global_state, self.dynamic_loader, True
-            )
-        except ValueError as e:
-            log.debug(
-                "Could not determine required parameters for call, putting fresh symbol on the stack. \n{}".format(
-                    e
-                )
-            )
-            global_state.mstate.stack.append(
-                global_state.new_bitvec("retval_" + str(instr["address"]), 256)
-            )
-            return [global_state]
-
-        if global_state.last_return_data is None:
-            # Put return value on stack
-            return_value = global_state.new_bitvec(
-                "retval_" + str(instr["address"]), 256
-            )
-            global_state.mstate.stack.append(return_value)
-            global_state.mstate.constraints.append(return_value == 0)
 
-            return [global_state]
+        return self.post_handler(global_state, function_name="call")
-
-        try:
-            memory_out_offset = (
-                util.get_concrete_int(memory_out_offset)
-                if isinstance(memory_out_offset, Expression)
-                else memory_out_offset
-            )
-            memory_out_size = (
-                util.get_concrete_int(memory_out_size)
-                if isinstance(memory_out_size, Expression)
-                else memory_out_size
-            )
-        except TypeError:
-            global_state.mstate.stack.append(
-                global_state.new_bitvec("retval_" + str(instr["address"]), 256)
-            )
-            return [global_state]
-
-        # Copy memory
-        global_state.mstate.mem_extend(
-            memory_out_offset, min(memory_out_size, len(global_state.last_return_data))
-        )
-        for i in range(min(memory_out_size, len(global_state.last_return_data))):
-            global_state.mstate.memory[
-                i + memory_out_offset
-            ] = global_state.last_return_data[i]
-
-        # Put return value on stack
-        return_value = global_state.new_bitvec("retval_" + str(instr["address"]), 256)
-        global_state.mstate.stack.append(return_value)
-        global_state.mstate.constraints.append(return_value == 1)
-
-        return [global_state]
 
     @StateTransition()
     def callcode_(self, global_state: GlobalState) -> List[GlobalState]:
@@ -1831,7 +1803,6 @@ class Instruction:
             callee_address, callee_account, call_data, value, gas, _, _ = get_call_parameters(
                 global_state, self.dynamic_loader, True
             )
-
             if callee_account is not None and callee_account.code.bytecode == "":
                 log.debug("The call is related to ether transfer between accounts")
                 sender = global_state.environment.active_account.address
@@ -1864,8 +1835,9 @@ class Instruction:
             callee_account=environment.active_account,
             call_data=call_data,
             call_value=value,
+            static=environment.static,
         )
-        raise TransactionStartSignal(transaction, self.op_code)
+        raise TransactionStartSignal(transaction, self.op_code, global_state)
 
     @StateTransition()
     def callcode_post(self, global_state: GlobalState) -> List[GlobalState]:
@@ -1949,7 +1921,7 @@ class Instruction:
 
             if callee_account is not None and callee_account.code.bytecode == "":
                 log.debug("The call is related to ether transfer between accounts")
-                sender = environment.active_account.address
+                sender = global_state.environment.active_account.address
                 receiver = callee_account.address
                 transfer_ether(global_state, sender, receiver, value)
 
@@ -1979,8 +1951,9 @@ class Instruction:
             callee_account=environment.active_account,
             call_data=call_data,
             call_value=environment.callvalue,
+            static=environment.static,
         )
-        raise TransactionStartSignal(transaction, self.op_code)
+        raise TransactionStartSignal(transaction, self.op_code, global_state)
 
     @StateTransition()
     def delegatecall_post(self, global_state: GlobalState) -> List[GlobalState]:
@@ -2012,6 +1985,7 @@ class Instruction:
                 "retval_" + str(instr["address"]), 256
             )
             global_state.mstate.stack.append(return_value)
+            global_state.mstate.constraints.append(return_value == 0)
             return [global_state]
 
         try:
@@ -2053,8 +2027,8 @@ class Instruction:
         :param global_state:
         :return:
         """
-        # TODO: implement me
         instr = global_state.get_current_instruction()
+        environment = global_state.environment
         try:
             callee_address, callee_account, call_data, value, gas, memory_out_offset, memory_out_size = get_call_parameters(
                 global_state, self.dynamic_loader
@@ -2062,7 +2036,7 @@ class Instruction:
 
             if callee_account is not None and callee_account.code.bytecode == "":
                 log.debug("The call is related to ether transfer between accounts")
-                sender = global_state.environment.active_account.address
+                sender = environment.active_account.address
                 receiver = callee_account.address
                 transfer_ether(global_state, sender, receiver, value)
 
@@ -2085,10 +2059,82 @@ class Instruction:
         native_result = native_call(
             global_state, callee_address, call_data, memory_out_offset, memory_out_size
         )
+
         if native_result:
             return native_result
 
-        global_state.mstate.stack.append(
+        transaction = MessageCallTransaction(
-            global_state.new_bitvec("retval_" + str(instr["address"]), 256)
+            world_state=global_state.world_state,
+            gas_price=environment.gasprice,
+            gas_limit=gas,
+            origin=environment.origin,
+            code=callee_account.code,
+            caller=environment.address,
+            callee_account=environment.active_account,
+            call_data=call_data,
+            call_value=value,
+            static=True,
         )
+        raise TransactionStartSignal(transaction, self.op_code, global_state)
+
+    def staticcall_post(self, global_state: GlobalState) -> List[GlobalState]:
+        return self.post_handler(global_state, function_name="staticcall")
+
+    def post_handler(self, global_state, function_name: str):
+        instr = global_state.get_current_instruction()
+
+        try:
+            callee_address, callee_account, call_data, value, gas, memory_out_offset, memory_out_size = get_call_parameters(
+                global_state, self.dynamic_loader, True
+            )
+        except ValueError as e:
+            log.debug(
+                "Could not determine required parameters for {}, putting fresh symbol on the stack. \n{}".format(
+                    function_name, e
+                )
+            )
+            global_state.mstate.stack.append(
+                global_state.new_bitvec("retval_" + str(instr["address"]), 256)
+            )
+            return [global_state]
+
+        if global_state.last_return_data is None:
+            # Put return value on stack
+            return_value = global_state.new_bitvec(
+                "retval_" + str(instr["address"]), 256
+            )
+            global_state.mstate.stack.append(return_value)
+            return [global_state]
+
+        try:
+            memory_out_offset = (
+                util.get_concrete_int(memory_out_offset)
+                if isinstance(memory_out_offset, Expression)
+                else memory_out_offset
+            )
+            memory_out_size = (
+                util.get_concrete_int(memory_out_size)
+                if isinstance(memory_out_size, Expression)
+                else memory_out_size
+            )
+        except TypeError:
+            global_state.mstate.stack.append(
+                global_state.new_bitvec("retval_" + str(instr["address"]), 256)
+            )
+            return [global_state]
+
+        # Copy memory
+        global_state.mstate.mem_extend(
+            memory_out_offset, min(memory_out_size, len(global_state.last_return_data))
+        )
+        for i in range(min(memory_out_size, len(global_state.last_return_data))):
+            global_state.mstate.memory[
+                i + memory_out_offset
+            ] = global_state.last_return_data[i]
+
+        # Put return value on stack
+        return_value = global_state.new_bitvec("retval_" + str(instr["address"]), 256)
+        global_state.mstate.stack.append(return_value)
+        global_state.mstate.constraints.append(return_value == 1)
+
         return [global_state]

mythril/laser/ethereum/state/environment.py

@@ -22,6 +22,7 @@ class Environment:
         callvalue: ExprRef,
         origin: ExprRef,
         code=None,
+        static=False,
     ) -> None:
         """
 
@@ -32,7 +33,7 @@ class Environment:
         :param callvalue:
         :param origin:
         :param code:
-        :param calldata_type:
+        :param static: Makes the environment static.
         """
         # Metadata
 
@@ -50,6 +51,7 @@ class Environment:
         self.gasprice = gasprice
         self.origin = origin
         self.callvalue = callvalue
+        self.static = static
 
     def __str__(self) -> str:
         """

mythril/laser/ethereum/svm.py

@@ -324,7 +324,9 @@ class LaserEVM:
                 global_state.transaction_stack
             ) + [(start_signal.transaction, global_state)]
             new_global_state.node = global_state.node
-            new_global_state.mstate.constraints = global_state.mstate.constraints
+            new_global_state.mstate.constraints = (
+                start_signal.global_state.mstate.constraints
+            )
 
             log.debug("Starting new transaction %s", start_signal.transaction)
 

mythril/laser/ethereum/transaction/transaction_models.py

@@ -45,9 +45,11 @@ class TransactionStartSignal(Exception):
         self,
         transaction: Union["MessageCallTransaction", "ContractCreationTransaction"],
         op_code: str,
+        global_state: GlobalState,
     ) -> None:
         self.transaction = transaction
         self.op_code = op_code
+        self.global_state = global_state
 
 
 class BaseTransaction:
@@ -66,6 +68,7 @@ class BaseTransaction:
         code=None,
         call_value=None,
         init_call_data=True,
+        static=False,
     ) -> None:
         assert isinstance(world_state, WorldState)
         self.world_state = world_state
@@ -101,7 +104,7 @@ class BaseTransaction:
             if call_value is not None
             else symbol_factory.BitVecSym("callvalue{}".format(identifier), 256)
         )
-
+        self.static = static
         self.return_data = None  # type: str
 
     def initial_global_state_from_environment(self, environment, active_function):
@@ -159,6 +162,7 @@ class MessageCallTransaction(BaseTransaction):
             self.call_value,
             self.origin,
             code=self.code or self.callee_account.code,
+            static=self.static,
         )
         return super().initial_global_state_from_environment(
             environment, active_function="fallback"

tests/instructions/static_call_test.py

@@ -0,0 +1,124 @@
+import pytest
+from mock import patch
+
+from mythril.disassembler.disassembly import Disassembly
+from mythril.laser.smt import symbol_factory
+from mythril.laser.ethereum.state.environment import Environment
+from mythril.laser.ethereum.state.account import Account
+from mythril.laser.ethereum.state.machine_state import MachineState
+from mythril.laser.ethereum.state.global_state import GlobalState
+from mythril.laser.ethereum.state.world_state import WorldState
+from mythril.laser.ethereum.instructions import Instruction
+from mythril.laser.ethereum.transaction.transaction_models import MessageCallTransaction
+from mythril.laser.ethereum.call import SymbolicCalldata
+from mythril.laser.ethereum.transaction import TransactionStartSignal
+
+from mythril.laser.ethereum.evm_exceptions import WriteProtection
+
+
+def get_global_state():
+    active_account = Account("0x0", code=Disassembly("60606040"))
+    environment = Environment(
+        active_account, None, SymbolicCalldata("2"), None, None, None
+    )
+    world_state = WorldState()
+    world_state.put_account(active_account)
+    state = GlobalState(world_state, environment, None, MachineState(gas_limit=8000000))
+    state.transaction_stack.append(
+        (MessageCallTransaction(world_state=world_state, gas_limit=8000000), None)
+    )
+    return state
+
+
+@patch(
+    "mythril.laser.ethereum.instructions.get_call_parameters",
+    return_value=(
+        "0",
+        Account(code=Disassembly(code="0x00"), address="0x19"),
+        0,
+        0,
+        0,
+        0,
+        0,
+    ),
+)
+def test_staticcall(f1):
+    # Arrange
+    state = get_global_state()
+    state.mstate.stack = [10, 10, 10, 10, 10, 10, 10, 10, 0]
+    instruction = Instruction("staticcall", dynamic_loader=None)
+
+    # Act and Assert
+    with pytest.raises(TransactionStartSignal) as ts:
+        instruction.evaluate(state)
+    assert ts.value.transaction.static
+    assert ts.value.transaction.initial_global_state().environment.static
+
+
+test_data = (
+    "suicide",
+    "create",
+    "create2",
+    "log0",
+    "log1",
+    "log2",
+    "log3",
+    "log4",
+    "sstore",
+)
+
+
+@pytest.mark.parametrize("input", test_data)
+def test_staticness(input):
+    # Arrange
+    state = get_global_state()
+    state.environment.static = True
+    state.mstate.stack = []
+    instruction = Instruction(input, dynamic_loader=None)
+
+    # Act and Assert
+    with pytest.raises(WriteProtection):
+        instruction.evaluate(state)
+
+
+test_data_call = ((0, True), (100, False))
+
+
+@pytest.mark.parametrize("input, success", test_data_call)
+@patch("mythril.laser.ethereum.instructions.get_call_parameters")
+def test_staticness_call_concrete(f1, input, success):
+    # Arrange
+    state = get_global_state()
+    state.environment.static = True
+    state.mstate.stack = []
+    code = Disassembly(code="616263")
+    f1.return_value = ("0", Account(code=code, address="0x19"), 0, input, 0, 0, 0)
+    instruction = Instruction("call", dynamic_loader=None)
+
+    # Act and Assert
+    if success:
+        with pytest.raises(TransactionStartSignal) as ts:
+            instruction.evaluate(state)
+        assert ts.value.transaction.static
+    else:
+        with pytest.raises(WriteProtection):
+            instruction.evaluate(state)
+
+
+@patch("mythril.laser.ethereum.instructions.get_call_parameters")
+def test_staticness_call_symbolic(f1):
+    # Arrange
+    state = get_global_state()
+    state.environment.static = True
+    state.mstate.stack = []
+    call_value = symbol_factory.BitVecSym("x", 256)
+    code = Disassembly(code="616263")
+    f1.return_value = ("0", Account(code=code, address="0x19"), 0, call_value, 0, 0, 0)
+    instruction = Instruction("call", dynamic_loader=None)
+
+    # Act and Assert
+    with pytest.raises(TransactionStartSignal) as ts:
+        instruction.evaluate(state)
+
+    assert ts.value.transaction.static
+    assert ts.value.global_state.mstate.constraints[-1] == (call_value == 0)