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@ -7,6 +7,139 @@ from mythril.laser.smt.bitvec import BitVec, Annotations |
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from mythril.laser.smt.bool import Or, Bool, And |
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def Concat(*args: Union[BitVec, List[BitVec]]) -> BitVec: |
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"""Create a concatenation expression. |
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:param args: |
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:return: |
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""" |
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# The following statement is used if a list is provided as an argument to concat |
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if len(args) == 1 and isinstance(args[0], list): |
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bvs = args[0] # type: List[BitVec] |
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else: |
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bvs = cast(List[BitVec], args) |
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concat_list = bvs |
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nraw = z3.Concat([a.raw for a in bvs]) |
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annotations = set() # type: Annotations |
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nested_functions = [] # type: List[BitVecFunc] |
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bfne_cnt = 0 |
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parent = None |
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for bv in bvs: |
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annotations = annotations.union(bv.annotations) |
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if isinstance(bv, BitVecFunc): |
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nested_functions += bv.nested_functions |
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nested_functions += [bv] |
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if isinstance(bv, BitVecFuncExtract): |
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if parent is None: |
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parent = bv.parent |
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if hash(parent.raw) != hash(bv.parent.raw): |
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continue |
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bfne_cnt += 1 |
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if bfne_cnt == len(bvs): |
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# check for continuity |
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fail = True |
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if bvs[-1].low == 0: |
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fail = False |
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for index, bv in enumerate(bvs): |
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if index == 0: |
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continue |
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if bv.high + 1 != bvs[index - 1].low: |
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fail = True |
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break |
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if fail is False: |
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if bvs[0].high == bvs[0].parent.size() - 1: |
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return bvs[0].parent |
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else: |
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return BitVecFuncExtract( |
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raw=nraw, |
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func_name=bvs[0].func_name, |
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input_=bvs[0].input_, |
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nested_functions=nested_functions, |
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concat_args=concat_list, |
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low=bvs[-1].low, |
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high=bvs[0].high, |
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parent=bvs[0].parent, |
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) |
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if nested_functions: |
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for bv in bvs: |
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bv.simplify() |
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return BitVecFunc( |
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raw=nraw, |
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func_name="Hybrid", |
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input_=BitVec(z3.BitVec("", 256), annotations=annotations), |
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nested_functions=nested_functions, |
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concat_args=concat_list, |
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) |
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return BitVec(nraw, annotations) |
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def Extract(high: int, low: int, bv: BitVec) -> BitVec: |
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"""Create an extract expression. |
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:param high: |
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:param low: |
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:param bv: |
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:return: |
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""" |
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raw = z3.Extract(high, low, bv.raw) |
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if isinstance(bv, BitVecFunc): |
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count = 0 |
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val = None |
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for small_bv in bv.concat_args[::-1]: |
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if low == count: |
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if low + small_bv.size() <= high: |
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val = small_bv |
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else: |
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val = Extract( |
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small_bv.size() - 1, |
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small_bv.size() - (high - low + 1), |
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small_bv, |
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) |
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elif high < count: |
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break |
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elif low < count: |
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if low + small_bv.size() <= high: |
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val = Concat(small_bv, val) |
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else: |
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val = Concat( |
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Extract( |
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small_bv.size() - 1, |
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small_bv.size() - (high - low + 1), |
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small_bv, |
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), |
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val, |
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) |
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count += small_bv.size() |
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if val is not None: |
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if isinstance(val, BitVecFuncExtract) and z3.simplify( |
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val.raw == val.parent.raw |
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): |
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val = val.parent |
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val.simplify() |
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return val |
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input_string = "" |
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# Is there a better value to set func_name and input to in this case? |
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return BitVecFuncExtract( |
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raw=raw, |
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func_name="Hybrid", |
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input_=BitVec(z3.BitVec(input_string, 256), annotations=bv.annotations), |
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nested_functions=bv.nested_functions + [bv], |
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low=low, |
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high=high, |
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parent=bv, |
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) |
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return BitVec(raw, annotations=bv.annotations) |
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def _arithmetic_helper( |
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a: "BitVecFunc", b: Union[BitVec, int], operation: Callable |
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) -> "BitVecFunc": |
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@ -68,12 +201,34 @@ def _comparison_helper( |
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operation = operator.lt |
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return Bool(z3.BoolVal(operation(a.value, b.value)), annotations=union) |
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if not isinstance(b, BitVecFunc) and a.potential_value: |
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if ( |
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a.size() == 512 |
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and b.size() == 512 |
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and z3.is_true( |
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z3.simplify(z3.Extract(255, 0, a.raw) == z3.Extract(255, 0, b.raw)) |
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) |
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): |
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a = Extract(511, 256, a) |
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b = Extract(511, 256, b) |
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if not isinstance(b, BitVecFunc): |
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if a.potential_value: |
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condition = False |
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for value, cond in a.potential_value: |
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if value is not None: |
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condition = Or(condition, And(b == value, cond)) |
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condition = Or(condition, And(operation(b, value), cond)) |
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return And(condition, operation(a.raw, b.raw)) |
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if b.pseudo_input and b.pseudo_input.size() >= a.input_.size(): |
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if b.pseudo_input.size() > a.input_.size(): |
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padded_a = z3.Concat( |
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z3.BitVecVal(0, b.pseudo_input.size() - a.input_.size()), |
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a.input_.raw, |
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) |
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else: |
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padded_a = a.input_.raw |
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print(b.pseudo_input.raw) |
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return And(operation(a.raw, b.raw), operation(padded_a, b.pseudo_input.raw)) |
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if ( |
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not isinstance(b, BitVecFunc) |
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or not a.func_name |
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@ -307,3 +462,38 @@ class BitVecFunc(BitVec): |
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def __hash__(self) -> int: |
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return self.raw.__hash__() |
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class BitVecFuncExtract(BitVecFunc): |
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"""A bit vector function wrapper, useful for preserving Extract() and Concat() operations""" |
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def __init__( |
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self, |
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raw: z3.BitVecRef, |
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func_name: Optional[str], |
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input_: "BitVec" = None, |
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annotations: Optional[Annotations] = None, |
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nested_functions: Optional[List["BitVecFunc"]] = None, |
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concat_args: List = None, |
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low=None, |
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high=None, |
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parent=None, |
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): |
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""" |
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:param raw: The raw bit vector symbol |
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:param func_name: The function name. e.g. sha3 |
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:param input: The input to the functions |
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:param annotations: The annotations the BitVecFunc should start with |
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""" |
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super().__init__( |
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raw=raw, |
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func_name=func_name, |
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input_=input_, |
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annotations=annotations, |
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nested_functions=nested_functions, |
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concat_args=concat_args, |
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) |
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self.low = low |
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self.high = high |
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self.parent = parent |
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