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fix: reject invalid x5c chain lengths before parsing #302

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fix: reject invalid x5c chain lengths before parsing #302

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11 changes: 7 additions & 4 deletions src/main/java/com/apple/itunes/storekit/verification/ChainVerifier.java
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,9 @@ public ChainVerifier(Set<InputStream> rootCertificates) {
}

public PublicKey verifyChain(String[] certificates, boolean performRevocationChecking, Date effectiveDate) throws VerificationException {
if (certificates == null) {
throw new VerificationException(VerificationStatus.INVALID_CHAIN_LENGTH);
}
if (performRevocationChecking && certificates.length > 0) {
// If revocation checking is enabled (which also implies effectiveDate is now), check the cache
PublicKey cachedKey = getCachedPublicKey(Arrays.asList(certificates));
Expand All @@ -77,6 +80,10 @@ public PublicKey verifyChain(String[] certificates, boolean performRevocationChe
}

PublicKey verifyChainWithoutCaching(String[] certificates, boolean performRevocationChecking, Date effectiveDate) throws VerificationException {
if (certificates.length != EXPECTED_CHAIN_LENGTH) {
throw new VerificationException(VerificationStatus.INVALID_CHAIN_LENGTH);
}

CertificateFactory certificateFactory;
CertPathValidator certPathValidator;
try {
Expand All @@ -95,10 +102,6 @@ PublicKey verifyChainWithoutCaching(String[] certificates, boolean performRevoca
throw new VerificationException(VerificationStatus.INVALID_CERTIFICATE, e);
}

if (parsedCertificates.size() != EXPECTED_CHAIN_LENGTH) {
throw new VerificationException(VerificationStatus.INVALID_CHAIN_LENGTH);
}

try {
//We don't include the root cert in the path, due to OCSP not being supported
CertPath certPath = certificateFactory.generateCertPath(parsedCertificates.subList(0, EXPECTED_CHAIN_LENGTH - 1));
Expand Down
29 changes: 29 additions & 0 deletions src/test/java/com/apple/itunes/storekit/verification/ChainVerifierTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,13 @@
import java.security.PublicKey;
import java.security.cert.CertPathValidator;
import java.security.cert.CertPathValidatorException;
import java.security.cert.CertificateFactory;
import java.time.Clock;
import java.time.Instant;
import java.util.Arrays;
import java.util.Base64;
import java.util.Date;
import java.util.List;
import java.util.Map;
import java.util.Set;

Expand Down Expand Up @@ -105,6 +108,32 @@ public void testInvalidChainLength() {
Assertions.assertEquals(VerificationStatus.INVALID_CHAIN_LENGTH, exception.getStatus());
}

@Test
public void testInvalidChainLengthsAreRejectedBeforeParsingCertificates() throws Exception {
ChainVerifier verifier = getChainVerifier(ROOT_CA_BASE64_ENCODED);
CertificateFactory certificateFactory = Mockito.mock(CertificateFactory.class);
String[] oversizedChain = new String[1_000];
Arrays.fill(oversizedChain, ROOT_CA_BASE64_ENCODED);

try (MockedStatic<CertificateFactory> mockedCertificateFactory = Mockito.mockStatic(CertificateFactory.class)) {
mockedCertificateFactory.when(() -> CertificateFactory.getInstance("X.509")).thenReturn(certificateFactory);

for (String[] invalidChain : List.<String[]>of(
new String[0],
new String[] {ROOT_CA_BASE64_ENCODED},
new String[] {ROOT_CA_BASE64_ENCODED, ROOT_CA_BASE64_ENCODED},
new String[] {ROOT_CA_BASE64_ENCODED, ROOT_CA_BASE64_ENCODED, ROOT_CA_BASE64_ENCODED, ROOT_CA_BASE64_ENCODED},
oversizedChain)) {
VerificationException exception = Assertions.assertThrows(
VerificationException.class,
() -> verifier.verifyChain(invalidChain, false, EFFECTIVE_DATE));
Assertions.assertEquals(VerificationStatus.INVALID_CHAIN_LENGTH, exception.getStatus());
}

Mockito.verifyNoInteractions(certificateFactory);
}
}

@Test
public void testMalformedBase64InCertificateList() {
ChainVerifier verifier = getChainVerifier(ROOT_CA_BASE64_ENCODED);
Expand Down