72 lines
3.3 KiB
Markdown
72 lines
3.3 KiB
Markdown
---
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id: review-002-fwd13-dot-segments
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name: Reject lone dot-dot path values that Url-set_path normalizes away (FWD-13)
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status: completed
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depends_on: []
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scope: narrow
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risk: medium
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impact: component
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level: implementation
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tags: [adapters, review-002, security, from-openapi]
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---
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## Description
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Review 002 FWD-13 [major, security]. Lone `.`/`..` path-parameter
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values survive the PATH_VALUE_ENCODE_SET (which has no `.`) and are
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**silently normalized away by `Url::set_path`** — empirically
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reproduced against the locked `url 2.5.8`:
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- `set_path("/tenants/../admin")` → `/admin`
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- `set_path("/files/..")` → `/`
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- `set_path("/repos/%2e%2e/x")` → `/x` (so adding `%2e` to the encode
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set would NOT fix it — the parser normalizes every case-insensitive
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spelling)
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Scenario: template `/tenants/{tenant}/resources` with peer input
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`tenant = ".."` → the upstream receives `/resources` — a *different*
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(east commonly less-scoped, list-everything) endpoint than the template
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describes, **with the namespace's injected credentials attached**. The
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existing dot-segment test (`traversal_value_cannot_escape_template_path`,
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forward.rs:1155) only covers the multi-segment `../../admin` form the
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encoder *does* catch. The origin check in `assemble_request_url`
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(:520-522) cannot catch this — the origin never changes.
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## Acceptance Criteria
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- [ ] Rendered path **values** that are exactly `.` or `..`
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(case-insensitive, including `%2e` spellings before encoding) are
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rejected with a loud `INVALID_INPUT`-family CallError — the
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cleanest point is `value_to_path_segment` / `render_path_template`
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- [ ] A post-`set_path` invariant assert (decoded path segments =
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base_dir + rendered segments, byte-identical) protects against
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future normalizer surprises (implementer's choice: debug_assert
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+ loud runtime check, or a property test with a dot/percent/binary
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corpus)
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- [ ] Tests: lone `..` value → error; lone `.` value → error; `%2e%2e`
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spelling → error; a *legitimate* segment containing a dot
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(`v1.2.3`, `.hidden-file` as a value) still works (the rejection
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is exact-match, not substring)
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- [ ] Existing traversal/encoding tests unchanged and passing
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- [ ] `cargo test`, `cargo clippy --all-targets -- -D warnings`,
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`cargo fmt --check` pass
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## References
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- docs/reviews/002-post-remediation-review.md (Part D', FWD-13)
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- src/adapters/forward.rs:340-352 (encode set lacking `.`), :413-448 (renderer), :481-531 (set_path + origin check), :1155 (the test family)
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- tasks/adapters/review-001-forward-url-safety.md (the FWD-01 fix this completes — one case short)
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## Notes
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The error message must not echo the raw value's neighbor inputs (no
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spec/content leakage beyond the parameter name — follow the existing
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message style in `render_path_template`'s unbound-placeholder error).
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FWD-18 (object/array placeholder values double-routing to query) is
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tracked separately in review-002-fwd17-19-contract-decisions — do not
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fold it here, the mechanisms are adjacent but the decisions differ.
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## Summary
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Lone ./.. (and %2e spellings) path values rejected INVALID_INPUT at value_to_path_segment; post-set_path normalization invariant in assemble_request_url; url 2.5.8 normalization empirically pinned; dotted-value legitimacy + segment-survival corpus tests.
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