8000 Master issue295 tsig fix by frankarinnet · Pull Request #296 · dnsjava/dnsjava · GitHub
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Master issue295 tsig fix #296

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b92bcd8
Issue 295, addresses bug with TSIG verification of large responses.
frankarinnet Oct 23, 2023
2def163
Neatened formatting.
frankarinnet Oct 23, 2023
9797928
Test for Issue 295 added as well as a related change to give more con…
nguichon Oct 25, 2023
3997863
Merge branch 'master_issue_295_test' into master_issue295_tsig_fix
nguichon Oct 25, 2023
87ae7ac
Edited docs for modified TSIG generate method
nguichon Oct 25, 2023
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125 changes: 97 additions & 28 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 @@ -132,7 +132,21 @@ public static String nameToAlgorithm(Name name) {
private final Name name;
private final SecretKey macKey;
private final String macAlgorithm;
private final Mac sharedHmac;

// TODO: This change of mine is incompatible with 62d1222e3088f106f05032cef7697da324d699d0 and needs to be resolved.
// As written, that changeset was based on the assumption that the hmac state did not need to persist across
// calls to TSIG.verify(). Unfortunately, this is false.
//
// a few possibilities offhand:
// 1. Give up on the thread safety promise for the TSIG instance.
// That's what I've done here (just because it is simplest), but it could break client assumptions.
// 2. Have the StreamVerifier instance manage the hmac lifecycle and pass it as a parameter to TSIG.verify().
// This seems best to me, but its necessary to think through backward compatibility issues for the API.
// 3. Use some sort of ThreadLocal cheese.
// That may cause more trouble than its worth given all DnsJava's nice async support. I don't know.
//
// I need a bit of guidance here on how to proceed.
private Mac sharedHmac;

/**
* Verifies the data (computes the secure hash and compares it to the input)
Expand Down Expand Up @@ -369,20 +383,44 @@ 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);
}

/**
* 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 +429,7 @@ public TSIGRecord generate(
fudge = Duration.ofSeconds(fudgeOption);
}

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

Expand Down Expand Up @@ -571,42 +609,68 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG) {
* @see Rcode
* @since 3.2
*/
// TODO: requestTSIG is now a bit misnamed. 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".
public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolean fullSignature) {
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;
}

// TODO: note thread local comment on line 136
sharedHmac = initHmac();

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

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

int len = m.tsigstart - header.length;
if (log.isTraceEnabled()) {
log.trace(hexdump.dump("TSIG-HMAC message after header", messageBytes, header.length, len));
}
hmac.update(messageBytes, header.length, len);

sharedHmac.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) {
Expand All @@ -630,10 +694,10 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolea
if (log.isTraceEnabled()) {
log.trace(hexdump.dump("TSIG-HMAC variables", tsigVariables));
}
hmac.update(tsigVariables);
sharedHmac.update(tsigVariables);

byte[] signature = tsig.getSignature();
int digestLength = hmac.getMacLength();
int digestLength = sharedHmac.getMacLength();

// rfc4635#section-3.1, 4.:
// "MAC size" field is less than the larger of 10 (octets) and half
Expand All @@ -651,7 +715,7 @@ public int verify(Message m, byte[] messageBytes, TSIGRecord requestTSIG, boolea
signature.length);
return Rcode.BADSIG;
} else {
byte[] expectedSignature = hmac.doFinal();
byte[] expectedSignature = sharedHmac.doFinal(); // note that doFinal also resets the hmac
if (!verify(expectedSignature, signature)) {
if (log.isDebugEnabled()) {
log.debug(
Expand All @@ -676,6 +740,12 @@ 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().
// FWIW, it was left dirty in the original working implementation.
// Add the current TSIG details to the HMAC for a possible next iteration
hmacAddSignature(sharedHmac, tsig);

m.tsigState = Message.TSIG_VERIFIED;
return Rcode.NOERROR;
}
Expand Down Expand Up @@ -767,8 +837,7 @@ 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);
}
}
}
Expand Down
122 changes: 108 additions & 14 deletions src/test/java/org/xbill/DNS/TSIGTest.java
8000
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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;
}
}
}
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