cpp: model Protocol Buffers parse/serialize taint flow - #22448
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Add flow summaries for the protobuf C++ API on google::protobuf::MessageLite (subtypes=true, so Message and all generated messages are covered): - ParseFrom*/MergeFrom* (string, array, Cord, istream, zero-copy and coded-stream forms) propagate taint from the encoded input to the message. - SerializeTo*/AppendTo* propagate taint from the message to the output buffer or stream; SerializeAs*/... to the return value. File-descriptor variants are omitted (the fd is an int, not a buffer).
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Pull request overview
Adds C++ taint-flow summaries for Protocol Buffers MessageLite APIs and inherited generated message types.
Changes:
- Models parse/merge and serialization flows.
- Adds representative flow tests and expected results.
- Documents the analysis improvement.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
cpp/ql/lib/ext/Protobuf.model.yml |
Defines protobuf flow summaries. |
cpp/ql/test/library-tests/dataflow/external-models/protobuf.cpp |
Adds protobuf test fixtures. |
cpp/ql/test/library-tests/dataflow/external-models/flow.expected |
Updates flow expectations. |
cpp/ql/test/library-tests/dataflow/external-models/steps.expected |
Updates summary-step expectations. |
cpp/ql/lib/change-notes/2026-08-27-protobuf-models.md |
Records the new models. |
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| - ["google::protobuf", "MessageLite", True, "ParseFromZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"] | ||
| - ["google::protobuf", "MessageLite", True, "ParsePartialFromZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"] | ||
| - ["google::protobuf", "MessageLite", True, "ParseFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"] | ||
| - ["google::protobuf", "MessageLite", True, "ParsePartialFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"] | ||
| - ["google::protobuf", "MessageLite", True, "MergeFromBoundedZeroCopyStream", "", "", "Argument[*0]", "Argument[-1]", "taint", "manual"] |
jketema
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jketema
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Thanks for this. I made a brief first pass over this, which should hopefully put you on the right path.
Co-authored-by: Jeroen Ketema <93738568+jketema@users.noreply.github.com>
jketema
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jketema
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Some further comments. I think the .yml file looks good now. I would still significantly reduce the number of comments, which don't seem to add much.
Replace the step-coverage function with one sink test per model row using a template source, declare the Cord overloads of the ToString methods in the stub, drop the incorrect istream comment from the fixture, and shorten the model-file and change-note comments per review.
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Internal testing showed nothing out of the ordinary. So if you fix the test, then this can be merged. |
jketema
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jketema
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LGTM. Going to fix the broken test afterwards to just get this in. Thanks for the contribution!
This apparently conflicts with the other PR of you that I just merged, and as don't have permission to push to your branch, I cannot resolve this myself. |
Add flow summaries for the protobuf C++ API on google::protobuf::MessageLite (subtypes=true, so Message and all generated messages are covered):