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fix: validate certificate field tags #67

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fix: validate certificate field tags #67

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9 changes: 8 additions & 1 deletion src/CertManager.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -360,8 +360,10 @@ contract CertManager is ICertManager {
function _certIdentity(bytes memory certificate, Asn1Ptr tbsCertPtr) internal pure returns (bytes32) {
Asn1Ptr versionPtr = certificate.firstChildOf(tbsCertPtr);
Asn1Ptr serialPtr = certificate.nextSiblingOf(versionPtr);
_requireAsn1Tag(certificate, serialPtr, 0x02);
Asn1Ptr sigAlgoPtr = certificate.nextSiblingOf(serialPtr);
Asn1Ptr issuerPtr = certificate.nextSiblingOf(sigAlgoPtr);
_requireAsn1Tag(certificate, issuerPtr, 0x30);
bytes32 serialHash = certificate.keccak(serialPtr.content(), serialPtr.length());
bytes32 issuerHash = certificate.keccak(issuerPtr.content(), issuerPtr.length());
return keccak256(abi.encodePacked(issuerHash, serialHash));
Expand All @@ -375,7 +377,9 @@ contract CertManager is ICertManager {
_requireAsn1Tag(certificate, ptr, 0x30);
Asn1Ptr versionPtr = certificate.firstChildOf(ptr);
_requireAsn1Tag(certificate, versionPtr, 0xa0);
Asn1Ptr sigAlgoPtr = certificate.nextSiblingOf(certificate.nextSiblingOf(versionPtr));
Asn1Ptr serialPtr = certificate.nextSiblingOf(versionPtr);
_requireAsn1Tag(certificate, serialPtr, 0x02);
Asn1Ptr sigAlgoPtr = certificate.nextSiblingOf(serialPtr);
_requireAsn1Tag(certificate, sigAlgoPtr, 0x30);

if (certificate.keccak(sigAlgoPtr.content(), sigAlgoPtr.length()) != CERT_ALGO_OID) {
Expand Down Expand Up @@ -432,6 +436,8 @@ contract CertManager is ICertManager {
Asn1Ptr subjectPublicKeyPtr = certificate.nextSiblingOf(pubKeyAlgoPtr);
Asn1Ptr subjectPubKeyPtr = certificate.bitstring(subjectPublicKeyPtr);

_requireAsn1Tag(certificate, pubKeyAlgoIdPtr, 0x06);
_requireAsn1Tag(certificate, algoParamsPtr, 0x06);
if (certificate.keccak(pubKeyAlgoIdPtr.content(), pubKeyAlgoIdPtr.length()) != EC_PUB_KEY_OID) {
revert InvalidSubjectPublicKey();
}
Expand Down Expand Up @@ -482,6 +488,7 @@ contract CertManager is ICertManager {
if (extensionEnd > end) revert InvalidExtension();
_requireAsn1Tag(certificate, extensionPtr, 0x30);
Asn1Ptr oidPtr = certificate.firstChildOf(extensionPtr);
_requireAsn1Tag(certificate, oidPtr, 0x06);
bytes32 oid = certificate.keccak(oidPtr.content(), oidPtr.length());
bool recognized = oid == BASIC_CONSTRAINTS_OID || oid == KEY_USAGE_OID;

Expand Down
77 changes: 77 additions & 0 deletions test/CertManager.t.sol
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Expand Up @@ -166,6 +166,49 @@ contract CertManagerTest is Test {
cm.verifyCACertWithHints(mutated, keccak256(CB0), "");
}

function test_ParseTbsRejectsSerialTagSubstitution() public {
vm.warp(1775145600);
CertManager cm = new CertManager(new P384Verifier());

bytes memory mutated = bytes.concat(CB1);
Asn1Ptr root = mutated.root();
Asn1Ptr tbsPtr = mutated.firstChildOf(root);
Asn1Ptr versionPtr = mutated.firstChildOf(tbsPtr);
Asn1Ptr serialPtr = mutated.nextSiblingOf(versionPtr);
mutated[serialPtr.header()] = 0x04;

vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
cm.verifyCACertWithHints(mutated, keccak256(CB0), "");
}

function test_ComputeCertIdRejectsSerialTagSubstitution() public {
bytes memory mutated = bytes.concat(CB1);
Asn1Ptr root = mutated.root();
Asn1Ptr tbsPtr = mutated.firstChildOf(root);
Asn1Ptr versionPtr = mutated.firstChildOf(tbsPtr);
Asn1Ptr serialPtr = mutated.nextSiblingOf(versionPtr);
mutated[serialPtr.header()] = 0x04;

CertManager cm = new CertManager(new P384Verifier());
vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
cm.computeCertId(mutated);
}

function test_ComputeCertIdRejectsIssuerTagSubstitution() public {
bytes memory mutated = bytes.concat(CB1);
Asn1Ptr root = mutated.root();
Asn1Ptr tbsPtr = mutated.firstChildOf(root);
Asn1Ptr versionPtr = mutated.firstChildOf(tbsPtr);
Asn1Ptr serialPtr = mutated.nextSiblingOf(versionPtr);
Asn1Ptr sigAlgoPtr = mutated.nextSiblingOf(serialPtr);
Asn1Ptr issuerPtr = mutated.nextSiblingOf(sigAlgoPtr);
mutated[issuerPtr.header()] = 0x31;

CertManager cm = new CertManager(new P384Verifier());
vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
cm.computeCertId(mutated);
}

function test_ParsePubKeyAcceptsUncompressedP384Point() public view {
bytes memory pubKey = _patternBytes(96);
bytes memory spki = abi.encodePacked(hex"3076301006072a8648ce3d020106052b8104002203620004", pubKey);
Expand Down Expand Up @@ -205,6 +248,40 @@ contract CertManagerTest is Test {
certManagerPubKeyHarness.parsePubKey(spki);
}

function test_ParsePubKeyRejectsAlgorithmOidTagSubstitution() public {
bytes memory pubKey = _patternBytes(96);
bytes memory mutated = abi.encodePacked(hex"3076301006072a8648ce3d020106052b8104002203620004", pubKey);
Asn1Ptr algorithmPtr = mutated.firstChildOf(mutated.root());
Asn1Ptr algorithmOidPtr = mutated.firstChildOf(algorithmPtr);
mutated[algorithmOidPtr.header()] = 0x05;

vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
certManagerPubKeyHarness.parsePubKey(mutated);
}

function test_ParsePubKeyRejectsCurveOidTagSubstitution() public {
bytes memory pubKey = _patternBytes(96);
bytes memory mutated = abi.encodePacked(hex"3076301006072a8648ce3d020106052b8104002203620004", pubKey);
Asn1Ptr algorithmPtr = mutated.firstChildOf(mutated.root());
Asn1Ptr algorithmOidPtr = mutated.firstChildOf(algorithmPtr);
Asn1Ptr curveOidPtr = mutated.nextSiblingOf(algorithmOidPtr);
mutated[curveOidPtr.header()] = 0x05;

vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
certManagerPubKeyHarness.parsePubKey(mutated);
}

function test_VerifyExtensionsRejectsOidTagSubstitution() public {
bytes memory mutated = _extensions(bytes.concat(_basicConstraintsExtension(), _keyUsageExtension()));
Asn1Ptr extensionSequencePtr = mutated.firstChildOf(mutated.root());
Asn1Ptr extensionPtr = mutated.firstChildOf(extensionSequencePtr);
Asn1Ptr oidPtr = mutated.firstChildOf(extensionPtr);
mutated[oidPtr.header()] = 0x05;

vm.expectRevert(CertManager.InvalidAsn1Tag.selector);
certManagerExtensionsHarness.verifyExtensions(mutated, true);
}

function test_VerifyExtensionsAllowsUnknownNonCriticalExtension() public view {
bytes memory unknownNameConstraints = hex"30090603551d1e04023000";

Expand Down
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