/*
* Copyright 2012-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.actuate.cloudfoundry;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import org.springframework.boot.actuate.cloudfoundry.CloudFoundryAuthorizationException.Reason;
import org.springframework.util.Base64Utils;
/**
* Validator used to ensure that a signed {@link Token} has not been tampered with.
*
* @author Madhura Bhave
*/
class TokenValidator {
private final CloudFoundrySecurityService securityService;
private Map<String, String> tokenKeys;
TokenValidator(CloudFoundrySecurityService cloudFoundrySecurityService) {
this.securityService = cloudFoundrySecurityService;
}
public void validate(Token token) {
validateAlgorithm(token);
validateKeyIdAndSignature(token);
validateExpiry(token);
validateIssuer(token);
validateAudience(token);
}
private void validateAlgorithm(Token token) {
String algorithm = token.getSignatureAlgorithm();
if (algorithm == null) {
throw new CloudFoundryAuthorizationException(Reason.INVALID_SIGNATURE,
"Signing algorithm cannot be null");
}
if (!algorithm.equals("RS256")) {
throw new CloudFoundryAuthorizationException(
Reason.UNSUPPORTED_TOKEN_SIGNING_ALGORITHM,
"Signing algorithm " + algorithm + " not supported");
}
}
private void validateKeyIdAndSignature(Token token) {
String keyId = token.getKeyId();
if (this.tokenKeys == null || !hasValidKeyId(keyId)) {
this.tokenKeys = this.securityService.fetchTokenKeys();
if (!hasValidKeyId(keyId)) {
throw new CloudFoundryAuthorizationException(Reason.INVALID_KEY_ID,
"Key Id present in token header does not match");
}
}
if (!hasValidSignature(token, this.tokenKeys.get(keyId))) {
throw new CloudFoundryAuthorizationException(Reason.INVALID_SIGNATURE,
"RSA Signature did not match content");
}
}
private boolean hasValidKeyId(String tokenKey) {
for (String candidate : this.tokenKeys.keySet()) {
if (tokenKey.equals(candidate)) {
return true;
}
}
return false;
}
private boolean hasValidSignature(Token token, String key) {
try {
PublicKey publicKey = getPublicKey(key);
Signature signature = Signature.getInstance("SHA256withRSA");
signature.initVerify(publicKey);
signature.update(token.getContent());
return signature.verify(token.getSignature());
}
catch (GeneralSecurityException ex) {
return false;
}
}
private PublicKey getPublicKey(String key)
throws NoSuchAlgorithmException, InvalidKeySpecException {
key = key.replace("-----BEGIN PUBLIC KEY-----\n", "");
key = key.replace("-----END PUBLIC KEY-----", "");
key = key.trim().replace("\n", "");
byte[] bytes = Base64Utils.decodeFromString(key);
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
return KeyFactory.getInstance("RSA").generatePublic(keySpec);
}
private void validateExpiry(Token token) {
long currentTime = TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis());
if (currentTime > token.getExpiry()) {
throw new CloudFoundryAuthorizationException(Reason.TOKEN_EXPIRED,
"Token expired");
}
}
private void validateIssuer(Token token) {
String uaaUrl = this.securityService.getUaaUrl();
String issuerUri = String.format("%s/oauth/token", uaaUrl);
if (!issuerUri.equals(token.getIssuer())) {
throw new CloudFoundryAuthorizationException(Reason.INVALID_ISSUER,
"Token issuer does not match " + uaaUrl + "/oauth/token");
}
}
private void validateAudience(Token token) {
if (!token.getScope().contains("actuator.read")) {
throw new CloudFoundryAuthorizationException(Reason.INVALID_AUDIENCE,
"Token does not have audience actuator");
}
}
}