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Code Issues Actions 2 Packages Projects Releases Wiki Activity

MINOR: Use time constant algorithms when comparing passwords or keys (#10978) 

Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Manikumar Reddy <manikumar@confluent.io>, Rajini Sivaram <rajinisivaram@gmail.com>, Mickael Maison <mickael.maison@gmail.com>, Ismael Juma <ijuma@apache.org>
This commit is contained in:
Randall Hauch 2021-07-30 17:48:03 -05:00
parent ee60cae8b0
commit da7a8db29e
6 changed files with 88 additions and 5 deletions
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4
clients/src/main/java/org/apache/kafka/common/security/plain/internals/PlainServerCallbackHandler.java
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@ -22,9 +22,9 @@ import org.apache.kafka.common.security.auth.AuthenticateCallbackHandler;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.security.plain.PlainAuthenticateCallback;
import org.apache.kafka.common.security.plain.PlainLoginModule;
import org.apache.kafka.common.utils.Utils;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
@ -65,7 +65,7 @@ public class PlainServerCallbackHandler implements AuthenticateCallbackHandler {
String expectedPassword = JaasContext.configEntryOption(jaasConfigEntries,
JAAS_USER_PREFIX + username,
PlainLoginModule.class.getName());
return expectedPassword != null && Arrays.equals(password, expectedPassword.toCharArray());
return expectedPassword != null && Utils.isEqualConstantTime(password, expectedPassword.toCharArray());
}
}

3
clients/src/main/java/org/apache/kafka/common/security/scram/internals/ScramSaslClient.java
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@ -18,6 +18,7 @@ package org.apache.kafka.common.security.scram.internals;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Collection;
@ -204,7 +205,7 @@ public class ScramSaslClient implements SaslClient {
try {
byte[] serverKey = formatter.serverKey(saltedPassword);
byte[] serverSignature = formatter.serverSignature(serverKey, clientFirstMessage, serverFirstMessage, clientFinalMessage);
if (!Arrays.equals(signature, serverSignature))
if (!MessageDigest.isEqual(signature, serverSignature))
throw new SaslException("Invalid server signature in server final message");
} catch (InvalidKeyException e) {
throw new SaslException("Sasl server signature verification failed", e);

3
clients/src/main/java/org/apache/kafka/common/security/scram/internals/ScramSaslServer.java
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@ -17,6 +17,7 @@
package org.apache.kafka.common.security.scram.internals;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.Collection;
@ -226,7 +227,7 @@ public class ScramSaslServer implements SaslServer {
byte[] expectedStoredKey = scramCredential.storedKey();
byte[] clientSignature = formatter.clientSignature(expectedStoredKey, clientFirstMessage, serverFirstMessage, clientFinalMessage);
byte[] computedStoredKey = formatter.storedKey(clientSignature, clientFinalMessage.proof());
if (!Arrays.equals(computedStoredKey, expectedStoredKey))
if (!MessageDigest.isEqual(computedStoredKey, expectedStoredKey))
throw new SaslException("Invalid client credentials");
} catch (InvalidKeyException e) {
throw new SaslException("Sasl client verification failed", e);

3
clients/src/main/java/org/apache/kafka/common/security/token/delegation/DelegationToken.java
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@ -18,6 +18,7 @@ package org.apache.kafka.common.security.token.delegation;
import org.apache.kafka.common.annotation.InterfaceStability;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.Base64;
import java.util.Objects;
@ -59,7 +60,7 @@ public class DelegationToken {
DelegationToken token = (DelegationToken) o;
return Objects.equals(tokenInformation, token.tokenInformation) && Arrays.equals(hmac, token.hmac);
return Objects.equals(tokenInformation, token.tokenInformation) && MessageDigest.isEqual(hmac, token.hmac);
}
@Override

36
clients/src/main/java/org/apache/kafka/common/utils/Utils.java
View File

@ -298,6 +298,42 @@ public final class Utils {
return t;
}
/**
* Compares two character arrays for equality using a constant-time algorithm, which is needed
* for comparing passwords. Two arrays are equal if they have the same length and all
* characters at corresponding positions are equal.
*
* All characters in the first array are examined to determine equality.
* The calculation time depends only on the length of this first character array; it does not
* depend on the length of the second character array or the contents of either array.
*
* @param first the first array to compare
* @param second the second array to compare
* @return true if the arrays are equal, or false otherwise
*/
public static boolean isEqualConstantTime(char[] first, char[] second) {
if (first == second) {
return true;
}
if (first == null || second == null) {
return false;
}
if (second.length == 0) {
return first.length == 0;
}
// time-constant comparison that always compares all characters in first array
boolean matches = first.length == second.length;
for (int i = 0; i < first.length; ++i) {
int j = i < second.length ? i : 0;
if (first[i] != second[j]) {
matches = false;
}
}
return matches;
}
/**
* Sleep for a bit
* @param ms The duration of the sleep

44
clients/src/test/java/org/apache/kafka/common/utils/UtilsTest.java
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@ -47,6 +47,8 @@ import static org.apache.kafka.common.utils.Utils.validHostPattern;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import static org.junit.Assert.fail;
import static org.mockito.ArgumentMatchers.any;
@ -487,4 +489,46 @@ public class UtilsTest {
} catch (IllegalArgumentException e) {
}
}
@Test
public void testCharacterArrayEquality() {
assertCharacterArraysAreNotEqual(null, "abc");
assertCharacterArraysAreNotEqual(null, "");
assertCharacterArraysAreNotEqual("abc", null);
assertCharacterArraysAreNotEqual("", null);
assertCharacterArraysAreNotEqual("", "abc");
assertCharacterArraysAreNotEqual("abc", "abC");
assertCharacterArraysAreNotEqual("abc", "abcd");
assertCharacterArraysAreNotEqual("abc", "abcdefg");
assertCharacterArraysAreNotEqual("abcdefg", "abc");
assertCharacterArraysAreEqual("abc", "abc");
assertCharacterArraysAreEqual("a", "a");
assertCharacterArraysAreEqual("", "");
assertCharacterArraysAreEqual("", "");
assertCharacterArraysAreEqual(null, null);
}
private void assertCharacterArraysAreNotEqual(String a, String b) {
char[] first = a != null ? a.toCharArray() : null;
char[] second = b != null ? b.toCharArray() : null;
if (a == null) {
assertNotNull(b);
} else {
assertFalse(a.equals(b));
}
assertFalse(Utils.isEqualConstantTime(first, second));
assertFalse(Utils.isEqualConstantTime(second, first));
}
private void assertCharacterArraysAreEqual(String a, String b) {
char[] first = a != null ? a.toCharArray() : null;
char[] second = b != null ? b.toCharArray() : null;
if (a == null) {
assertNull(b);
} else {
assertTrue(a.equals(b));
}
assertTrue(Utils.isEqualConstantTime(first, second));
assertTrue(Utils.isEqualConstantTime(second, first));
}
}