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Marius CiepluchandClaude Fable 5.1
4d56b3c76e
Task 1.1 (Req 2.1-2.4). Spec approved by the maintainer in session. - semantic/variants.py: Shape (language, sink trailing name, arity, source positions and kinds, closed guard kind, mechanism id) with a stable text-free key; derive_shape finds the labeled sink call site in the vulnerable FileIR, traces argument identifiers through binds to a fact source, a parameter or a container read, and classifies the guard the fixed side added from the labeled function's added statements against a closed set (none when unknown). No path, line or literal enters a shape; a constant-only call teaches nothing. Co-Authored-By: Claude Fable 5.1 <[email protected]> Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
77 lines
3.4 KiB
Python
77 lines
3.4 KiB
Python
"""corpus-seeded-mechanisms: structural shapes derived from pairs and matched on trees (offline, stdlib ast)."""
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from __future__ import annotations
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from openultrasast.semantic.facts import load_facts
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from openultrasast.semantic.ir import parse_file
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VULN = "from flask import request\nimport os\n\n\ndef run():\n cmd = request.args.get('cmd')\n os.system(cmd)\n"
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FIXED = (
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"from flask import request\nimport os\n\nALLOWED = {'ls', 'date'}\n\n\ndef run():\n cmd = request.args.get('cmd')\n"
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" if cmd not in ALLOWED:\n return None\n os.system(cmd)\n"
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)
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def _derive(vuln: str = VULN, fixed: str = FIXED, **overrides: object):
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from openultrasast.semantic.variants import derive_shape
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kwargs: dict[str, object] = {"function": "run", "sink": "os.system", "line": None, "mechanism": "source_reaches_sink"}
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kwargs.update(overrides)
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return derive_shape(
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parse_file("app.py", vuln, "python"),
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parse_file("app.py", fixed, "python"),
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vuln_text=vuln,
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fixed_text=fixed,
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facts=load_facts(),
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**kwargs,
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)
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def test_derive_shape_from_a_request_to_os_system_pair_with_an_allowlist_fix() -> None:
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from openultrasast.semantic.variants import GUARD_KINDS, SOURCE_KINDS
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shape = _derive()
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assert shape is not None
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assert shape.language == "python" and shape.sink_name == "system" and shape.arity == 1
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assert shape.source_positions == (0,) and shape.source_kinds == ("fact_source",)
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assert shape.guard == "allowlist_test" and shape.guard in GUARD_KINDS and shape.mechanism == "source_reaches_sink"
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assert set(shape.source_kinds) <= set(SOURCE_KINDS)
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def test_shape_key_is_stable_and_carries_no_path_line_or_literal() -> None:
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a, b = _derive(), _derive()
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assert a is not None and b is not None and a.key() == b.key()
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key = a.key()
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for forbidden in ("app.py", "cmd", "'ls'", "request.args", ":6", ":7"):
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assert forbidden not in key
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# the same code in another file with different variable names is the same shape
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other_vuln = VULN.replace("cmd", "command")
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other = _derive(other_vuln, FIXED.replace("cmd", "command"))
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assert other is not None and other.key() == key
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def test_parameter_and_container_read_sources_are_classified() -> None:
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vuln = "import os\n\n\ndef run(payload, cmd):\n target = payload['t']\n os.system(cmd + target)\n"
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fixed = (
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"import os\n\n\ndef run(payload, cmd):\n target = payload['t']\n if len(target) > 32:\n return None\n"
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" os.system(cmd + target)\n"
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)
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shape = _derive(vuln, fixed)
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assert shape is not None
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assert shape.source_positions == (0,)
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assert shape.source_kinds in {("parameter",), ("container_read",)} # one argument carrying both; the kind is the first found
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assert shape.guard == "bounds_test"
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def test_unlabeled_or_missing_sink_returns_none_and_guard_defaults_to_none() -> None:
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assert _derive(sink="subprocess.run") is None # the label names a sink the function never calls
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assert _derive(function="other") is None # no such function
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same = _derive(VULN, VULN)
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assert same is not None and same.guard == "none" # no statement differs on the fixed side
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constant = "import os\n\n\ndef run():\n os.system('ls')\n"
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assert _derive(constant, constant) is None # a constant argument carries no source: nothing to learn
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def test_parse_failed_side_yields_no_shape() -> None:
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assert _derive("def run(:\n", FIXED) is None
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