fix(webauthn): escape clientDataJSON strings per CCDToString#196
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fix(webauthn): escape clientDataJSON strings per CCDToString#196AlfioEmanueleFresta wants to merge 1 commit into
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ClientData::to_json hand-rolled a JSON object with format!(), concatenating the origin and topOrigin strings unescaped. An origin containing a double quote, backslash, or U+0000-U+001F produced malformed JSON, and a hostile origin like 'https://example.com","origin":"https://attacker.com' yielded a document with two 'origin' keys. WebAuthn L3 §5.8.1.2 requires strings be encoded via CCDToString, which is a strict subset of RFC 8259 string-escape rules. Route serialization through a serde-derived struct that mirrors the spec field order (type, challenge, origin, topOrigin?, crossOrigin) so serde_json applies the correct escapes. Add regression tests covering hostile origins and topOrigins (double quote, backslash, control characters), spec-conformant field ordering with and without topOrigin, and a full round-trip.
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WebAuthn L3 §5.8.1.2 specifies that
clientDataJSONstrings must be escaped viaCCDToString(a strict subset of ECMA-262 / RFC 8259 string-escape rules).ClientData::to_jsoncurrently hand-rolls a JSON object viaformat!(), concatenating theoriginandtopOriginstrings unescaped, which produces malformed or attacker-injectable JSON when those strings contain",\, or U+0000-U+001F.Empirical repro on the base branch: setting
origintohttps://example.com","origin":"https://attacker.comyields a document with twooriginkeys.Stacked on top of #190 (which is stacked on #188 / #186). The
RequestOriginplumbing introduced by #188 already correctly populatesClientData::originandClientData::top_originfrom the URL origin; that work is preserved unchanged here.Changes
format!()inClientData::to_jsonwith a#[derive(Serialize)]wire struct that mirrors the spec field order (type,challenge,origin,topOrigin?,crossOrigin).serde_json's RFC 8259 string encoder is a strict superset ofCCDToString.topOriginis omitted from the output entirely when absent (viaskip_serializing_if), preserving the existing behaviour.", origin containing\, origin containing U+0000-U+001F control characters, hostiletopOrigin, spec field order with and withouttopOrigin, and a full round-trip.Test plan
cargo buildcargo test --lib(159 passed, including 11 inclient_data::tests)cargo fmt --checkcargo clippy --lib --all-features --no-deps -- -D warningsRefs: WebAuthn L3 §5.8.1.2 (
CCDToString); audit dossiers D-01, D-02, D-04, B-10, H-04, H-05.