Going all the way to the AST layer seemed excessive to me, so I rewrote
it to do most of the logic at the data-flow layer. In principle this
_could_ result in more names being computed (due to splitting), but in
practice I don't expect this make a big difference.
According to the official documentation, the purpose of `__main__.py`
files is that their presence in a package (say, `foo`) means one can
execute the package directly using `python -m foo` (which will run the
aforementioned `foo/__main__.py` file).
In principle this means that adding `if __name__ == "__main__"` in these
files is superfluous, as they are only intended to be executed (and not
imported by some other file).
However, in practice people often _do_ include the above construct.
Here are some instances of this on LGTM.com:
https://lgtm.com/query/7521266095072095777/
In particular, 10 out of 33 files in `cpython` have this construct.
This causes some confusion in our module naming, as we usually see the
presence of `__name__ == "__main__"` as an indication that a file may
be run directly (and hence with "absolute import" semantics). However,
when run with `python -m`, the interpreter uses the usual package
semantics, and this leads to modules getting multiple names.
For this reason, I think it makes sense to simply exclude `__main__.py`
files from consideration. Note that if there is a `#!` line mentioning
the Python interpreter, then they will still be included as entry
points.
Just like our support for the `PyYAML` PyPI package that you import with
`import yaml` is in `Yaml.qll`.
Since this file does not provide any public predicates/modules, it
should be safe to rename it.
So it better matches what is in `py/code-injection`. I had my doubts
about CWE-95, but after reading
https://owasp.org/www-community/attacks/Direct_Dynamic_Code_Evaluation_Eval%20Injection
I think it's fine to add CWE-95 as well 👍
Definitions are:
CWE-78: Improper Neutralization of Special Elements used in an OS
Command ('OS Command Injection')
CWE-94: Improper Control of Generation of Code ('Code Injection')
CWE-95: Improper Neutralization of Directives in Dynamically Evaluated
Code ('Eval Injection')
