Flips the Python dataflow trunk from the legacy CFG (semmle/python/Flow.qll)
and legacy ESSA SSA (semmle/python/essa/*) to the new shared CFG facade
(semmle.python.controlflow.internal.Cfg) and the new SSA adapter
(semmle.python.dataflow.new.internal.SsaImpl), both introduced
additively in the preceding PRs in this stack.
This is the trunk-flip equivalent of the original draft PR #21894 (kept
around as documentation), rebased on top of the four preparatory PRs:
P1: Remove AstNode.getAFlowNode() and rewrite callers (#21919).
P2: Qualify Flow.qll's AST references with Py:: prefix (#21920).
P3: Add new shared-CFG-backed control flow graph (#21921).
P4: Add new shared-SSA-backed SSA adapter (#21923).
The Python dataflow library (semmle/python/dataflow/new/) now imports
the new CFG facade and SSA adapter. All CFG-typed predicates
(ControlFlowNode, CallNode, BasicBlock, NameNode, AttrNode, ...) are
qualified with the Cfg:: prefix; SSA references switch from
EssaVariable/EssaDefinition to SsaImpl::Definition/SourceVariable.
GuardNode is redesigned to use the new CFG's outcome-node model
(isAfterTrue / isAfterFalse) instead of the legacy ConditionBlock +
flipped indirection. Only BarrierGuard<...> is preserved as public
API.
Framework files (Bottle, FastApi, Django, Tornado, Pyramid, Stdlib,
...) are updated to take CFG nodes from the new facade.
A handful of dataflow consistency tweaks for the new CFG:
- Augmented-assignment targets are treated as both load and store.
- 'from X import *' produces uncertain SSA writes for unknown names.
- CFG nodes are canonicalised so dataflow does not see equivalent
pre/post-order pairs as distinct nodes.
Two AST tweaks for the new CFG:
- AstNodeImpl: omit PEP 695 type-parameter names from
FunctionDefExpr / ClassDefExpr children.
- ImportResolution: drop the legacy essa import.
Test churn (~175 files): reblessed library- and query-test .expected
files reflect slightly different CFG granularity, different toString
output, and a handful of true alert deltas in security queries.
Verification: all 367 lib + src + consistency-queries compile clean.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Also fixes an issue with the return type annotations that caused these
to not work properly.
Currently, annotated assignments don't work properly, due to the fact
that our flow relation doesn't consider flow going to the "type" part of
an annotated assignment. This means that in `x : Foo`, we do correctly
note that `x` is annotated with `Foo`, but we have no idea what `Foo`
is, since it has no incoming flow.
To fix this we should probably just extend the flow relation, but this
may need to be done with some care, so I have left it as future work.
In reality, we only want to model this as a `rest_framework.response.Response`, since our .qll modeling is more precise for rest-framework responses than if we also modeled it as a basic django http response. (specifically, that default mime-type handling is way different).
I fixed it in both predicates... I think we might still be able to remove
`newDirectAlias` -- but with it being better, it will allow us to better test if `newImportAlias` actually cover everything we need!
Due to the 'only model most specific spec' logic highlighted in previous
commit, I'm changing away from MethodView/View, and use Django view instead.
In practice this shouldn't matter at all, but for writing tests it would
have been a nice fix to only have the "same name but more specific"
logic apply when it's the same _definition_ location. We used to have
this information available, but right now we don't... so instead of
spending a lot of time rewriting the core library, I simply used a
different class :D :O :(
- `--max-import-depth=3` to give points-to a chance
- `not_root` dir to force namespace package logic
- add usage in `example.py` to get files extracted
