[pysa question] Can't model __setitem__ on object of unknown type

[diogotcorreia]

Hey,

I'm trying to model the obj[key] = value construct on an obj of possibly unknown type. I don't care about the type of obj and want to mark all calls to __setitem__ as a sink.

Example code:

text: str = input()
text1: str = input()
text2: str = input()

class A:
    pass

a = A()

def my_func():
    foo = getattr(a, text)
    foo[text1] = text2

my_func()

I've tried adding the sink to dict.__setitem__, and creating the models using the DSL. This is my .pysa file:

@SkipObscure
def getattr(
    __o: TaintInTaintOut[Via[customgetattr]],
    __name,
    __default: TaintInTaintOut[LocalReturn],
) -> TaintSource[CustomGetAttr, ViaValueOf[__name, WithTag["get-name"]]]: ...

@SkipOverrides
@SkipObscure
def dict.__setitem__(
    __o: TaintSink[CustomSetItem, ViaValueOf[__name, WithTag["set-name"]], ViaValueOf[__value, WithTag["set-value"]]],
    __name,
    __value,
): ...

ModelQuery(
  name = "get_setitem_calls_funcs",
  find = "functions",
  where = [name.matches("__setitem__")],
  model = [
    Parameters(
      TaintSink[CustomSetItem],
      where=[
        index.equals(0)
      ]
    ),
  ],
)

ModelQuery(
  name = "get_setitem_calls_methods",
  find = "methods",
  where = [name.matches("__setitem__")],
  model = [
    Parameters(
      TaintSink[CustomSetItem],
      where=[
        index.equals(0)
      ]
    ),
  ],
)

I've ran pysa with some debugging and got this, which I think is the cause of the issue; pysa cannot figure out what the function call refers to:

19:4-19:24 -> {"__setitem__" -> { call =
                                  (Some { call_targets = [];
                                          new_targets = [];
                                          init_targets = [];
                                          decorated_targets = [];
                                          higher_order_parameters = {};
                                          unresolved =
                                          (CallGraph.Unresolved.True
                                             (CallGraph.Unresolved.BypassingDecorators
                                                CallGraph.Unresolved.UnknownBaseType));
                                          recognized_call = False });
                                  attribute_access = None;
                                  identifier = None; string_format = None
                                  }}

Is there any way to get pysa to use one of the models, even if the base type is unknown?

Thanks in advance