This solution was the best I could come up with, but it _is_ a bit
brittle since you need to remember to add this additional taint step
to any configuration that relies on sensitive data sources... I don't
see an easy way around this though :|
The comment about imports was placed wrong. I also realized we didn't
even have a single test-case for
`this.(DataFlow::AttrRead).getAttributeNameExpr() = sensitiveLookupStringConst(classification)`
so I added that (notice that this is only `getattr(foo, x)` and not
`getattr(foo, "password")`)
This was an unwanted interaction between two unrelated tests, so I
switched to a different built-in in the second test. I also added a test
case that shows an unfortunate side effect of this more restricted
handling of built-ins.
This commit does a lot of stuff all at once, so here are the main
highlights:
In `TypeTracker.qll`, we change `StepSummary::step` to step only between
source nodes. Because reads and writes of global variables happen in two
different (jump) steps, this requires the intermediate
`ModuleVariableNode` to _also_ be a `LocalSourceNode`, and we therefore
modify the charpred for that class accordingly. (This also means
changing a few of the tests to account for these new source nodes.)
In addition, we change `TypeTracker::step` to likewise step between
local source nodes.
Next, to enable the use of the `track` convenience method on nodes, we
add some pragmas to `TypeTracker::step` that prevent bad joins from
occurring. With this, we can eliminate all of the manual type tracker
join predicates.
Next, we observe that because `StepSummary::step` now uses `flowsTo`, it
automatically encapsulates all local-flow steps. In particular this
means we do not have to use `typePreservingStep` in `smallstep`, but can
use `jumpStep` directly. A similar observation applies to
`TypeTracker::smallstep`.
Having done this, we no longer need `typePreservingStep`, so we get rid
of it.
The meat of this PR is described in the new python/ql/test/experimental/meta/InlineTaintTest.qll file:
> Defines a InlineExpectationsTest for checking whether any arguments in
> `ensure_tainted` and `ensure_not_tainted` calls are tainted.
>
> Also defines query predicates to ensure that:
> - if any arguments to `ensure_not_tainted` are tainted, their annotation is marked with `SPURIOUS`.
> - if any arguments to `ensure_tainted` are not tainted, their annotation is marked with `MISSING`.
>
> The functionality of this module is tested in `ql/test/experimental/meta/inline-taint-test-demo`.
Since it's exposed nicely in the version that doesn't have a
`DataFlow::TypeTracker` parameter, these should be private.
Also found one instance where I had accidentially used DataFlow::Node instead of
LocalSourceNode
Although it is becoming non-trivial to get an overview of what tests we have and
don't have, I didn't find any that highlighted this one
I used all 3 variants of parameters, just to be sure :)
