chore(iast): taint flask request args and form

[gnufede]

Code security: Flask request args and form were not tainted as required.

Also: Some code was on the ASM side and actually belongs to IAST, so it's moved now.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

ddtrace/appsec/_asm_request_context.py                                  @DataDog/asm-python
ddtrace/appsec/_iast/_handlers.py                                       @DataDog/asm-python
ddtrace/appsec/_iast/_listener.py                                       @DataDog/asm-python
tests/contrib/flask/test_flask_appsec_iast.py                           @DataDog/asm-python

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: gnufede/APPSEC-56293-iast-flask-taint-http-request-parameter-name
Commit report: 9e4efe3
Test service: dd-trace-py

✅ 0 Failed, 87 Passed, 1468 Skipped, 3m 42.08s Total duration (35m 26.35s time saved)

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-13 11:46:16

Comparing candidate commit 8be39ef in PR branch gnufede/APPSEC-56293-iast-flask-taint-http-request-parameter-name with baseline commit 4beeccc in branch main.

Found 0 performance improvements and 1 performance regressions! Performance is the same for 393 metrics, 2 unstable metrics.

scenario:iast_aspects-ospathbasename_aspect

• 🟥 execution_time [+244.611ns; +305.926ns] or [+7.338%; +9.177%]