Disable JWKS signature verification if URL fails

src/main/java/org/jenkinsci/plugins/oic/OicJsonWebTokenVerifier.java

@@ -28,14 +28,17 @@
 import com.google.api.client.json.webtoken.JsonWebSignature;
 import hudson.Util;
 import java.io.IOException;
+import java.util.logging.Logger;
 
 /**
  * Extend IdTokenVerifier to verify UserInfo webtoken
  */
 public class OicJsonWebTokenVerifier extends IdTokenVerifier {
 
-    /** Bypass Signature verification if no JWKS url configured */
-    private final boolean hasNoJwksServerUrl;
+    private static final Logger LOGGER = Logger.getLogger(OicJsonWebTokenVerifier.class.getName());
+
+    /** Bypass Signature verification if JWKS url is not available */
+    private boolean jwksServerUrlAvailable;
 
     /** Payload indicating userInfo */
     private static final IdToken.Payload NO_PAYLOAD = new IdToken.Payload();
@@ -45,38 +48,51 @@ public class OicJsonWebTokenVerifier extends IdTokenVerifier {
      */
     public OicJsonWebTokenVerifier() {
         super();
-        hasNoJwksServerUrl = true;
+        jwksServerUrlAvailable = false;
     }
 
     /**
      * Verifier with custom builder
      */
     public OicJsonWebTokenVerifier(String jwksServerUrl, IdTokenVerifier.Builder builder) {
         super(builder.setCertificatesLocation(jwksServerUrl));
-        hasNoJwksServerUrl = (Util.fixEmptyAndTrim(jwksServerUrl) == null);
+        jwksServerUrlAvailable = (Util.fixEmptyAndTrim(jwksServerUrl) != null);
+    }
+
+    /** JWKS verfication enabled - for tests only */
+    public boolean isJwksServerUrlAvailable() {
+        return jwksServerUrlAvailable;
     }
 
+
     /** Verify real idtoken */
     public boolean verifyIdToken(IdToken idToken) throws IOException {
-        if (hasNoJwksServerUrl) {
-            /* avoid Google's certificate fallback mechanism */
-            return super.verifyPayload(idToken);
+        if (isJwksServerUrlAvailable()) {
+            try {
+                return verifyOrThrow(idToken);
+            } catch(IOException e) {
+                LOGGER.warning("IdToken signature verification failed '" + e.toString() + "' - jwks signature verification disabled");
+                jwksServerUrlAvailable = false;
+            }
         }
-        return verifyOrThrow(idToken);
+        return super.verifyPayload(idToken);
     }
 
     /** Verify userinfo jwt token */
     public boolean verifyUserInfo(JsonWebSignature userinfo) throws IOException {
-        if (hasNoJwksServerUrl) {
-            /* avoid Google's certificate fallback mechanism */
-            return true;
+        if (isJwksServerUrlAvailable()) {
+            try {
+                IdToken idToken = new IdToken(
+                        userinfo.getHeader(),
+                        NO_PAYLOAD, /* bypass verification of payload */
+                        userinfo.getSignatureBytes(),
+                        userinfo.getSignedContentBytes());
+                return verifyOrThrow(idToken);
+            } catch(IOException e) {
+                LOGGER.warning("UserInfo signature verification failed '" + e.toString() + "' - ignore");
+            }
         }
-        IdToken idToken = new IdToken(
-                userinfo.getHeader(),
-                NO_PAYLOAD, /* bypass verification of payload */
-                userinfo.getSignatureBytes(),
-                userinfo.getSignedContentBytes());
-        return verifyOrThrow(idToken);
+        return true;
     }
 
     /** hack: verify payload only if idtoken is not userinfo */

src/test/java/org/jenkinsci/plugins/oic/OicJsonWebTokenVerifierTest.java

@@ -0,0 +1,180 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) 2024 JenkinsCI oic-auth-plugin developers
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package org.jenkinsci.plugins.oic;
+
+import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
+import com.github.tomakehurst.wiremock.junit.WireMockRule;
+import com.google.api.client.auth.openidconnect.IdToken;
+import com.google.api.client.json.JsonFactory;
+import com.google.api.client.json.gson.GsonFactory;
+import com.google.api.client.json.webtoken.JsonWebSignature;
+import com.google.api.client.util.Base64;
+import com.google.api.client.util.Clock;
+import com.google.api.client.util.SecurityUtils;
+import com.google.api.client.util.StringUtils;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.interfaces.RSAPublicKey;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Rule;
+import org.junit.Test;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.get;
+import static com.github.tomakehurst.wiremock.client.WireMock.urlPathEqualTo;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class OicJsonWebTokenVerifierTest {
+
+    @Rule
+    public WireMockRule wireMockRule = new WireMockRule(new WireMockConfiguration().dynamicPort(), true);
+
+    KeyPair keyPair = createKeyPair();
+
+    @Test
+    public void testVanillaCaseShouldbeSuccessful() throws Exception {
+        wireMockRule.resetAll();
+        IdToken idtoken = createIdToken(keyPair.getPrivate(), new HashMap<>());
+        OicJsonWebTokenVerifier verifier = new OicJsonWebTokenVerifier(
+                "http://localhost:" + wireMockRule.port() + "/jwks",
+                new OicJsonWebTokenVerifier.Builder()
+                );
+        assertTrue(verifier.isJwksServerUrlAvailable());
+
+        wireMockRule.stubFor(get(urlPathEqualTo("/jwks"))
+                .willReturn(aResponse()
+                        .withHeader("Content-Type", "application/json")
+                        .withBody("{\"keys\":[{"+encodePublicKey(keyPair)+
+                            ",\"alg\":\"RS256\""+
+                            ",\"use\":\"sig\",\"kid\":\"jwks_key_id\""+
+                            "}]}")));
+
+        assertTrue(verifier.verifyIdToken(idtoken));
+        assertTrue(verifier.isJwksServerUrlAvailable());
+    }
+
+    @Test
+    public void tesNoJWKSURIShouldBeSuccessful() throws Exception {
+        IdToken idtoken = createIdToken(keyPair.getPrivate(), new HashMap<>());
+        OicJsonWebTokenVerifier verifier = new OicJsonWebTokenVerifier(
+                null,
+                new OicJsonWebTokenVerifier.Builder()
+                );
+        assertFalse(verifier.isJwksServerUrlAvailable());
+
+        assertTrue(verifier.verifyIdToken(idtoken));
+    }
+
+    @Test
+    public void testCannotGetJWKSURIShouldbeSuccessful() throws Exception {
+        wireMockRule.resetAll();
+        IdToken idtoken = createIdToken(keyPair.getPrivate(), new HashMap<>());
+        OicJsonWebTokenVerifier verifier = new OicJsonWebTokenVerifier(
+                "http://localhost:" + wireMockRule.port() + "/jwks",
+                new OicJsonWebTokenVerifier.Builder()
+                );
+        assertTrue(verifier.isJwksServerUrlAvailable());
+
+        wireMockRule.stubFor(get(urlPathEqualTo("/jwks"))
+                .willReturn(aResponse().withStatus(404)));
+
+        assertTrue(verifier.verifyIdToken(idtoken));
+        assertFalse(verifier.isJwksServerUrlAvailable());
+    }
+
+    @Test
+    public void testMissingAlgShouldbeSuccessful() throws Exception {
+        wireMockRule.resetAll();
+        IdToken idtoken = createIdToken(keyPair.getPrivate(), new HashMap<>());
+        OicJsonWebTokenVerifier verifier = new OicJsonWebTokenVerifier(
+                "http://localhost:" + wireMockRule.port() + "/jwks",
+                new OicJsonWebTokenVerifier.Builder()
+                );
+        assertTrue(verifier.isJwksServerUrlAvailable());
+
+        wireMockRule.stubFor(get(urlPathEqualTo("/jwks"))
+                .willReturn(aResponse()
+                        .withHeader("Content-Type", "application/json")
+                        .withBody("{\"keys\":[{"+encodePublicKey(keyPair)+
+                            ",\"use\":\"sig\",\"kid\":\"jwks_key_id\""+
+                            "}]}")));
+
+        assertTrue(verifier.verifyIdToken(idtoken));
+        assertFalse(verifier.isJwksServerUrlAvailable());
+    }
+
+    static private KeyPair createKeyPair() {
+        try {
+            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
+            keyGen.initialize(2048);
+            return keyGen.generateKeyPair();
+        } catch (NoSuchAlgorithmException e) {
+            /* should not happen */
+        }
+        return null;
+    }
+
+    private IdToken createIdToken(PrivateKey privateKey, Map<String, Object> keyValues) throws Exception {
+        JsonWebSignature.Header header = new JsonWebSignature.Header()
+            .setAlgorithm("RS256")
+            .setKeyId("jwks_key_id");
+        long now = (long)(Clock.SYSTEM.currentTimeMillis()/1000);
+        IdToken.Payload payload = new IdToken.Payload()
+            .setExpirationTimeSeconds(now + 60L)
+            .setIssuedAtTimeSeconds(now)
+            .setIssuer("issuer")
+            .setSubject("sub")
+            .setAudience(Collections.singletonList("clientId"))
+            .setNonce("nonce");
+        for (Map.Entry<String, Object> keyValue : keyValues.entrySet()) {
+            payload.set(keyValue.getKey(), keyValue.getValue());
+        }
+
+        JsonFactory jsonFactory = GsonFactory.getDefaultInstance();
+        String content =
+            Base64.encodeBase64URLSafeString(jsonFactory.toByteArray(header))
+            + "."
+            + Base64.encodeBase64URLSafeString(jsonFactory.toByteArray(payload));
+        byte[] contentBytes = StringUtils.getBytesUtf8(content);
+        byte[] signature =
+            SecurityUtils.sign(
+                    SecurityUtils.getSha256WithRsaSignatureAlgorithm(), privateKey, contentBytes);
+        return new IdToken(header, payload, signature, contentBytes);
+    }
+
+    /** Generate JWKS entry with public key of keyPair */
+    String encodePublicKey(KeyPair keyPair) {
+        final RSAPublicKey rsaPKey = (RSAPublicKey)(keyPair.getPublic());
+        return "\"n\":\"" +
+            Base64.encodeBase64String(rsaPKey.getModulus().toByteArray()) +
+            "\",\"e\":\"" +
+            Base64.encodeBase64String(rsaPKey.getPublicExponent().toByteArray()) +
+            "\",\"kty\":\"RSA\"";
+    }
+}