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Issue 295, addresses bug with TSIG verification of large responses. #298

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5b8d9da
Issue 295, addresses bug with TSIG verification of large responses.
frankarinnet Oct 24, 2023
120c1f2
Test for Issue 295 added as well as a related change to give more con…
nguichon Oct 25, 2023
bd160e5
Issue 295, removed direct references to shared_hmac.
frankarinnet Oct 26, 2023
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122 changes: 97 additions & 25 deletions src/main/java/org/xbill/DNS/TSIG.java
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Original file line number Diff line number Diff line change
Expand Up @@ -132,6 +132,7 @@ public static String nameToAlgorithm(Name name) {
private final Name name;
private final SecretKey macKey;
private final String macAlgorithm;

private final Mac sharedHmac;

/**
Expand Down Expand Up @@ -369,20 +370,50 @@ public TSIGRecord generate(Message m, byte[] b, int error, TSIGRecord old) {
*/
public TSIGRecord generate(
Message m, byte[] b, int error, TSIGRecord old, boolean fullSignature) {
Mac hmac = null;
boolean signing = false;

if (error == Rcode.NOERROR || error == Rcode.BADTIME || error == Rcode.BADTRUNC) {
signing = true;
hmac = initHmac();
}

return generate(m, b, error, old, hmac, true, signing, fullSignature);
}

// TODO - We had to introduce this to implement interleaved tsig requests for the test of StreamVerifier.
// A couple possiblities going forward for this:
// 1. Make the ability to send multiple messages with a shared hmac a full feature
// 2. Keep this test-only refactor of TSIG.generate
// 3. Duplicate this method with this feature in the test class as to not to expose/maintain it as part of the public API
/**
* Generates a TSIG record with a specific error for a message that has been rendered. This version is useful
* if you want to send multiple Messages without TSIGs in between.
*
*
* @param m The message
* @param b The rendered message
* @param error The error
* @param old If this message is a response, the TSIG from the request
* @param hmac Hmac to use with this generate, will be cleared if signing completes
* @param addOldSignatureFirst Makes a call to hmacAddSignature before signing. This should be false and hmacAddSignature
* should be called manually if you are attemping to send multiple Messages without TSIGs
* @param fullSignature {@code true} if this {@link TSIGRecord} is the to be added to the first of
* many messages in a TCP connection and all TSIG variables (rfc2845, 3.4.2.) should be
* included in the signature. {@code false} for subsequent messages with reduced TSIG
* variables set (rfc2845, 4.4.).
* @return The TSIG record to be added to the message
* @since 3.2
*/
public TSIGRecord generate(
Message m, byte[] b, int error, TSIGRecord old, Mac hmac, boolean addOldSignatureFirst, boolean signing, boolean fullSignature) {
Instant timeSigned;
if (error == Rcode.BADTIME) {
timeSigned = old.getTimeSigned();
} else {
timeSigned = clock.instant();
}

boolean signing = false;
Mac hmac = null;
if (error == Rcode.NOERROR || error == Rcode.BADTIME || error == Rcode.BADTRUNC) {
signing = true;
hmac = initHmac();
}

Duration fudge;
int fudgeOption = Options.intValue("tsigfudge");
if (fudgeOption < 0 || fudgeOption > 0x7FFF) {
Expand All @@ -391,7 +422,7 @@ public TSIGRecord generate(
fudge = Duration.ofSeconds(fudgeOption);
}

if (old != null && signing) {
if (old != null && addOldSignatureFirst && signing) {
hmacAddSignature(hmac, old);
}

Expand Down Expand Up @@ -572,42 +603,74 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG) {
* @since 3.2
*/
public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolean fullSignature) {
Mac hmac = initHmac();
int rval = verify(m, messageBytes, requestTSIG, fullSignature, hmac);
hmac.reset(); // TODO: this should help maintain exact backward compatibility for certain weird sharedHmac cases
return rval;
}

// TODO: introducing this method means we dont have to use the sharedHmac directly
// TODO: requestTSIG is a bit misnamed here. It is, indeed, the request TSIG on the first iteration.
// But in later iterations where the response is larger than 100 messages in length,
// it is just the "lastTSIG".
// TODO: unsure if this should be public or private
private int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolean fullSignature, Mac hmac) {
m.tsigState = Message.TSIG_FAILED;
TSIGRecord tsig = m.getTSIG();
if (tsig == null) {
return Rcode.FORMERR;
}

if (!tsig.getName().equals(name) || !tsig.getAlgorithm().equals(alg)) {
log.debug(
if (fullSignature) {
if (!tsig.getName().equals(name) || !tsig.getAlgorithm().equals(alg)) {
log.debug(
"BADKEY failure on message id {}, expected: {}/{}, actual: {}/{}",
m.getHeader().getID(),
name,
alg,
tsig.getName(),
tsig.getAlgorithm());
return Rcode.BADKEY;
return Rcode.BADKEY;
}

// add the query tsig to the HMAC
if (requestTSIG != null && tsig.getError() != Rcode.BADKEY && tsig.getError() != Rcode.BADSIG) {
hmacAddSignature(hmac, requestTSIG);
}
}

Mac hmac = initHmac();
if (requestTSIG != null && tsig.getError() != Rcode.BADKEY && tsig.getError() != Rcode.BADSIG) {
hmacAddSignature(hmac, requestTSIG);
if (tsig != null) {
m.getHeader().decCount(Section.ADDITIONAL);
}

m.getHeader().decCount(Section.ADDITIONAL);
byte[] header = m.getHeader().toWire();
m.getHeader().incCount(Section.ADDITIONAL);

if (tsig != null) {
m.getHeader().incCount(Section.ADDITIONAL);
}

if (log.isTraceEnabled()) {
log.trace(hexdump.dump("TSIG-HMAC header", header));
}
hmac.update(header);

int len = m.tsigstart - header.length;
int len;
if (tsig != null) {
len = m.tsigstart - header.length;
} else {
len = messageBytes.length - header.length;
}

if (log.isTraceEnabled()) {
log.trace(hexdump.dump("TSIG-HMAC message after header", messageBytes, header.length, len));
}

hmac.update(messageBytes, header.length, len);

// TODO: style question whether to prefer "return early" or to have a single return at the end.
// return early for the intermediate messages between tsigs
if (tsig == null) {
m.tsigState = Message.TSIG_INTERMEDIATE;
return Rcode.NOERROR;
}

DNSOutput out = new DNSOutput();
if (fullSignature) {
tsig.getName().toWireCanonical(out);
Expand Down Expand Up @@ -651,7 +714,7 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolea
signature.length);
return Rcode.BADSIG;
} else {
byte[] expectedSignature = hmac.doFinal();
byte[] expectedSignature = hmac.doFinal(); // note that doFinal also resets the hmac
if (!verify(expectedSignature, signature)) {
if (log.isDebugEnabled()) {
log.debug(
Expand All @@ -676,6 +739,12 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolea
return Rcode.BADTIME;
}

// TODO: this leaves the hmac "dirty" at the end of the last message verification.
// But I don't see a way around it without adding more parameters to TSIG.verify().
// Need to think if this could cause problems for users of the sharedHmac feature.
// Add the current TSIG details to the HMAC for a possible next iteration
hmacAddSignature(hmac, tsig);

m.tsigState = Message.TSIG_VERIFIED;
return Rcode.NOERROR;
}
Expand Down Expand Up @@ -723,6 +792,8 @@ public static class StreamVerifier {
/** A helper class for verifying multiple message responses. */
private final TSIG key;

// TODO: moving the MAC into StreamVerifier means a TSIG instance can remain stateless/thread safe
private final Mac mac;
private int nresponses;
private int lastsigned;
private TSIGRecord lastTSIG;
Expand All @@ -732,6 +803,8 @@ public StreamVerifier(TSIG tsig, TSIGRecord queryTsig) {
key = tsig;
nresponses = 0;
lastTSIG = queryTsig;
mac = tsig.initHmac();
mac.reset(); // TODO: unsure if certain weird sharedHmac cases might require this
}

/**
Expand All @@ -749,13 +822,13 @@ public int verify(Message m, byte[] b) {

nresponses++;
if (nresponses == 1) {
int result = key.verify(m, b, lastTSIG);
int result = key.verify(m, b, lastTSIG, true, mac);
lastTSIG = tsig;
return result;
}

if (tsig != null) {
int result = key.verify(m, b, lastTSIG, false);
int result = key.verify(m, b, lastTSIG, false, mac);
lastsigned = nresponses;
lastTSIG = tsig;
return result;
Expand All @@ -767,8 +840,7 @@ public int verify(Message m, byte[] b) {
return Rcode.FORMERR;
} else {
log.trace("Intermediate message {} without signature", nresponses);
m.tsigState = Message.TSIG_INTERMEDIATE;
return Rcode.NOERROR;
return key.verify(m, b, lastTSIG, false, mac);
}
}
}
Expand Down
122 changes: 108 additions & 14 deletions src/test/java/org/xbill/DNS/TSIGTest.java
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Original file line number Diff line number Diff line change
@@ -1,29 +1,30 @@
// SPDX-License-Identifier: BSD-3-Clause
package org.xbill.DNS;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertNotEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.anyInt;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.mockito.MockedStatic;
import org.mockito.Mockito;
import org.xbill.DNS.utils.base64;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.time.Duration;
import java.time.Instant;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Executor;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.ValueSource;
import org.mockito.MockedStatic;
import org.mockito.Mockito;
import org.xbill.DNS.utils.base64;

import static org.junit.jupiter.api.Assertions.*;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.anyInt;

class TSIGTest {
@Test
Expand Down Expand Up @@ -325,4 +326,97 @@ void testTSIGMessageClone() throws IOException {
assertNotNull(cloneBytes);
assertNotEquals(0, cloneBytes.length);
}

@Test
void testTSIGStreamVerifier() throws IOException, NoSuchAlgorithmException, InvalidKeyException {
MockMessageClient client = new MockMessageClient(new TSIG(TSIG.HMAC_SHA256, "example.", "12345678"));
MockMessageServer server = new MockMessageServer(new TSIG(TSIG.HMAC_SHA256, "example.", "12345678"));

byte[] query = client.createQuery();
List<byte[]> response = server.handleQuery(query, 100, 6);
client.validateResponse(query, response);
}

private static class MockMessageClient {
private final TSIG key;

MockMessageClient(TSIG key) {
this.key = key;
}

byte[] createQuery() throws TextParseException {
Name qname = Name.fromString("www.example.");
Record question = Record.newRecord(qname, Type.A, DClass.IN);
Message query = Message.newQuery(question);
query.setTSIG(key);
return query.toWire(Message.MAXLENGTH);
}

public void validateResponse(byte[] query, List<byte[]> response) throws IOException {
Message queryMessage = new Message(query);
TSIG.StreamVerifier verifier = new TSIG.StreamVerifier(key, queryMessage.getTSIG());

for (byte[] resBytes : response) {
Message resMessage = new Message(resBytes);
assertEquals(Rcode.NOERROR, verifier.verify(resMessage, resBytes));
}
}
}

private static class MockMessageServer {
private final TSIG key;

MockMessageServer(TSIG key) {
this.key = key;
}

List<byte[]> handleQuery(byte[] queryMessageBytes, int responseMessageCount, int signEvery) throws IOException, NoSuchAlgorithmException, InvalidKeyException {
Message parsedQueryMessage = new Message(queryMessageBytes);
assertNotNull(parsedQueryMessage.getTSIG());

List<byte[]> responseMessageList = new LinkedList<>();
TSIGRecord lastTsigRecord = parsedQueryMessage.getTSIG();

// Create an HMAC that is shared by messages between each TSIGRecord
Mac sharedHmac = Mac.getInstance("HmacSHA256");
sharedHmac.init(new SecretKeySpec(base64.fromString("12345678"), "HmacSHA256"));

for (int i = 0; i < responseMessageCount; i++) {
Message response = new Message(parsedQueryMessage.getHeader().getID());
response.getHeader().setFlag(Flags.QR);
response.addRecord(parsedQueryMessage.getQuestion(), Section.QUESTION);
Record answer = Record.fromString(parsedQueryMessage.getQuestion().getName(), Type.A, DClass.IN, 300, "1.2.3." + i, null);
response.addRecord(answer, Section.ANSWER);

boolean isNthMessage = i % signEvery == 0;
boolean isLastMessage = i == responseMessageCount - 1;
boolean isFirstMessage = i == 0;
if (isFirstMessage || isNthMessage || isLastMessage) {
byte[] unsignedResponseBytes = response.toWire();

// Create TSIGRecord for the latest message, the trick here is that prior messages without a TSIG have already
// been added to the sharedHmac
lastTsigRecord = key.generate(response, unsignedResponseBytes, Rcode.NOERROR, lastTsigRecord, sharedHmac, isFirstMessage, true, isFirstMessage);
response.addRecord(lastTsigRecord, Section.ADDITIONAL);
response.tsigState = Message.TSIG_SIGNED;

// Store message as a "response"
byte[] signedResponseBytes = response.toWire(Message.MAXLENGTH);
responseMessageList.add(signedResponseBytes);

// The call to generate above called doFinal and cleared sharedHmac, starting a new collection of signatures
// and the first thing that needs to be put in it is the previous signature.
byte[] signatureSize = DNSOutput.toU16(lastTsigRecord.getSignature().length);
sharedHmac.update(signatureSize);
sharedHmac.update(lastTsigRecord.getSignature());
} else {
byte[] responseBytes = response.toWire(Message.MAXLENGTH);
sharedHmac.update(responseBytes);
responseMessageList.add(responseBytes);
}
}

return responseMessageList;
}
}
}