fix(verify): require TDX quote version 4 and validate expected digest lengths in verify_tdx_quote and verify_sev_snp_report (#283)

src/ca2a_verify/sev_snp.py

@@ -83,6 +83,18 @@ def verify_sev_snp_report(
     ``agent_manifest.PLATFORM_INFO_BITS``. Both default to ``None``, which
     appraises nothing and leaves prior behaviour unchanged.
     """
+    if expected_measurement is not None and (
+        not isinstance(expected_measurement, (bytes, bytearray, memoryview))
+        or len(expected_measurement) != 48
+    ):
+        raise ValueError("expected_measurement must be a 48-byte SNP measurement")
+    if expected_report_data is not None and (
+        not isinstance(expected_report_data, (bytes, bytearray, memoryview))
+        or len(expected_report_data) != 64
+    ):
+        raise ValueError("expected_report_data must be a 64-byte SNP report_data value")
+    if not isinstance(reject_unrecognized_platform_bits, bool):
+        raise ValueError("reject_unrecognized_platform_bits must be a boolean")
     report = SevSnpReport.parse(report_bytes)
 
     if report.signature_algo != SIG_ALGO_ECDSA_P384_SHA384:
@@ -155,6 +167,8 @@ def sev_snp_verifier(
         raise ValueError("expected_measurement must be a 48-byte SNP measurement")
     if type(min_guest_svn) is not int or not 0 <= min_guest_svn <= 0xFFFFFFFF:
         raise ValueError("min_guest_svn must be an unsigned 32-bit integer")
+    if not isinstance(reject_unrecognized_platform_bits, bool):
+        raise ValueError("reject_unrecognized_platform_bits must be a boolean")
     roots, chain = list(trusted_roots), list(vcek_chain)
     required, forbidden = set(require_platform), set(forbid_platform)
 

src/ca2a_verify/tdx.py

@@ -54,8 +54,21 @@ def verify_tdx_quote(
     expected_report_data: bytes | None = None,
 ) -> TdxQuote:
     """Appraise a TDX quote offline. Raises AttestationFailed on any failure."""
+    if expected_mrtd is not None and (
+        not isinstance(expected_mrtd, (bytes, bytearray, memoryview)) or len(expected_mrtd) != 48
+    ):
+        raise ValueError("expected_mrtd must be a 48-byte TDX MRTD")
+    if expected_report_data is not None and (
+        not isinstance(expected_report_data, (bytes, bytearray, memoryview))
+        or len(expected_report_data) != 64
+    ):
+        raise ValueError("expected_report_data must be a 64-byte TDX report_data value")
     quote = TdxQuote.parse(quote_bytes)
 
+    if quote.version != 4:
+        raise AttestationFailed(
+            "unsupported TDX quote version", detail=f"version={quote.version}, expected 4"
+        )
     if quote.tee_type != TEE_TYPE_TDX:
         raise AttestationFailed("quote is not a TDX quote", detail=f"tee_type={quote.tee_type:#x}")
 

tests/unit/test_tdx.py

@@ -260,3 +260,54 @@ def test_trailing_padding_after_the_signature_section_is_ignored(quote_and_root)
         expected_mrtd=quote_and_root["mrtd"],
         expected_report_data=quote_and_root["rd"],
     )
+
+
+@pytest.mark.parametrize("bad_version", [3, 5, 0])
+def test_verify_tdx_quote_rejects_non_v4_version(quote_and_root, bad_version: int) -> None:
+    q = bytearray(quote_and_root["quote"])
+    struct.pack_into("<H", q, 0, bad_version)
+    with pytest.raises(AttestationFailed, match="unsupported TDX quote version"):
+        verify_tdx_quote(bytes(q), trusted_roots=[quote_and_root["root"]])
+
+
+@pytest.mark.parametrize(
+    ("bad_mrtd", "bad_rd"),
+    [
+        (b"\x11" * 47, None),
+        (b"\x11" * 49, None),
+        ("not-bytes", None),
+        (None, b"\x22" * 63),
+        (None, b"\x22" * 65),
+        (None, "not-bytes"),
+    ],
+)
+def test_verify_tdx_quote_and_sev_snp_reject_malformed_expected_digests(
+    quote_and_root, bad_mrtd, bad_rd
+) -> None:
+    from ca2a_verify.sev_snp import sev_snp_verifier, verify_sev_snp_report
+
+    with pytest.raises(ValueError):
+        verify_tdx_quote(
+            quote_and_root["quote"],
+            trusted_roots=[quote_and_root["root"]],
+            expected_mrtd=bad_mrtd,
+            expected_report_data=bad_rd,
+        )
+    with pytest.raises(ValueError):
+        verify_sev_snp_report(
+            b"\x00" * 1184,
+            [],
+            trusted_roots=[],
+            expected_measurement=bad_mrtd,
+            expected_report_data=bad_rd,
+        )
+    with pytest.raises(ValueError, match="reject_unrecognized_platform_bits"):
+        sev_snp_verifier(
+            trusted_roots=[],
+            vcek_chain=[],
+            expected_measurement=b"\x11" * 48,
+            min_guest_svn=1,
+            require_platform=set(),
+            forbid_platform=set(),
+            reject_unrecognized_platform_bits="yes",  # type: ignore[arg-type]
+        )