[Redback] Denylist for Syft

[arpitvaghela]

Description

Adding denylist for syft to explicitly deny methods and classes.
This will help us tackle security issues that may arise on moving syft libs support out of syft.

Affected Dependencies

How has this been tested?

• Manually

Checklist

• I have followed the Contribution Guidelines and Code of Conduct
• I have commented my code following the OpenMined Styleguide
• I have labeled this PR with the relevant Type labels
• My changes are covered by tests

[arpitvaghela]

Note: Remove pandas.read_csv and pandas.read_json in syft/libs/pandas/__init__.py before merging.

[iamtrask]

Would love to learn more about the decision to enforce a policy using a denylist instead of (or perhap sin addition to) an allowlist. For example, if numpy introduced a new method "read_json_v2" and we didn't notice, would that create a vulnerability by which someone could access the file system?

[arpitvaghela]

We are still following an allowlist policy, but since we are planning on moving the lib support out, we are added a denylist in syft itself that looks into allowlist of libs (which may or may not be created by us) and deny methods that may cause issues.