Support multiple audience for jwt authentication

src/main/java/com/amazon/dlic/auth/http/jwt/AbstractHTTPJwtAuthenticator.java

@@ -16,6 +16,7 @@
 import java.security.PrivilegedAction;
 import java.text.ParseException;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
@@ -61,7 +62,7 @@ public abstract class AbstractHTTPJwtAuthenticator implements HTTPAuthenticator
     private final String jwtUrlParameter;
     private final String subjectKey;
     private final String rolesKey;
-    private final String requiredAudience;
+    private final List<String> requiredAudience;
     private final String requiredIssuer;
 
     public static final int DEFAULT_CLOCK_SKEW_TOLERANCE_SECONDS = 30;
@@ -74,7 +75,7 @@ public AbstractHTTPJwtAuthenticator(Settings settings, Path configPath) {
         rolesKey = settings.get("roles_key");
         subjectKey = settings.get("subject_key");
         clockSkewToleranceSeconds = settings.getAsInt("jwt_clock_skew_tolerance_seconds", DEFAULT_CLOCK_SKEW_TOLERANCE_SECONDS);
-        requiredAudience = settings.get("required_audience");
+        requiredAudience = settings.getAsList("required_audience");
         requiredIssuer = settings.get("required_issuer");
 
         if (!jwtHeaderName.equals(AUTHORIZATION)) {
@@ -255,7 +256,7 @@ public Optional<SecurityResponse> reRequestAuthentication(final SecurityRequest
         );
     }
 
-    public String getRequiredAudience() {
+    public List<String> getRequiredAudience() {
         return requiredAudience;
     }
 

src/main/java/com/amazon/dlic/auth/http/jwt/HTTPJwtAuthenticator.java

@@ -16,6 +16,7 @@
 import java.security.PrivilegedAction;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
@@ -37,6 +38,7 @@
 import org.opensearch.security.user.AuthCredentials;
 import org.opensearch.security.util.KeyUtils;
 
+import com.nimbusds.jwt.proc.BadJWTException;
 import io.jsonwebtoken.Claims;
 import io.jsonwebtoken.JwtParser;
 import io.jsonwebtoken.JwtParserBuilder;
@@ -58,7 +60,7 @@
     private final String jwtUrlParameter;
     private final String rolesKey;
     private final String subjectKey;
-    private final String requireAudience;
+    private final List<String> requiredAudience;
     private final String requireIssuer;
 
     public HTTPJwtAuthenticator(final Settings settings, final Path configPath) {
@@ -70,7 +72,7 @@
         isDefaultAuthHeader = AUTHORIZATION.equalsIgnoreCase(jwtHeaderName);
         rolesKey = settings.get("roles_key");
         subjectKey = settings.get("subject_key");
-        requireAudience = settings.get("required_audience");
+        requiredAudience = settings.getAsList("required_audience");
         requireIssuer = settings.get("required_issuer");
 
         if (!jwtHeaderName.equals(AUTHORIZATION)) {
@@ -84,10 +86,6 @@
         if (jwtParserBuilder == null) {
             jwtParser = null;
         } else {
-            if (requireAudience != null) {
-                jwtParserBuilder.requireAudience(requireAudience);
-            }
-
             if (requireIssuer != null) {
                 jwtParserBuilder.requireIssuer(requireIssuer);
             }
@@ -161,6 +159,10 @@
         try {
             final Claims claims = jwtParser.parseClaimsJws(jwtToken).getBody();
 
+            if (!requiredAudience.isEmpty()) {
+                assertValidAudienceClaim(claims);
+            }
+
             final String subject = extractSubject(claims, request);
 
             if (subject == null) {
@@ -189,6 +191,16 @@
         }
     }
 
+    private void assertValidAudienceClaim(Claims claims) throws BadJWTException {
+        if (requiredAudience.isEmpty()) {
+            return;
+        }
+
+        if (Collections.disjoint(claims.getAudience(), requiredAudience)) {
+            throw new BadJWTException("Claim of 'aud' doesn't contain any required audience.");
+        }
+    }
+
     @Override
     public Optional<SecurityResponse> reRequestAuthentication(final SecurityRequest channel, AuthCredentials creds) {
         return Optional.of(

src/main/java/com/amazon/dlic/auth/http/jwt/keybyoidc/JwtVerifier.java

@@ -13,6 +13,8 @@
 
 import java.text.ParseException;
 import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
 
 import com.google.common.base.Strings;
 import org.apache.commons.lang3.StringEscapeUtils;
@@ -38,9 +40,9 @@ public class JwtVerifier {
     private final KeyProvider keyProvider;
     private final int clockSkewToleranceSeconds;
     private final String requiredIssuer;
-    private final String requiredAudience;
+    private final List<String> requiredAudience;
 
-    public JwtVerifier(KeyProvider keyProvider, int clockSkewToleranceSeconds, String requiredIssuer, String requiredAudience) {
+    public JwtVerifier(KeyProvider keyProvider, int clockSkewToleranceSeconds, String requiredIssuer, List<String> requiredAudience) {
         this.keyProvider = keyProvider;
         this.clockSkewToleranceSeconds = clockSkewToleranceSeconds;
         this.requiredIssuer = requiredIssuer;
@@ -116,9 +118,10 @@ private void validateClaims(SignedJWT jwt) throws ParseException, BadJWTExceptio
 
         if (claims != null) {
             DefaultJWTClaimsVerifier<SimpleSecurityContext> claimsVerifier = new DefaultJWTClaimsVerifier<>(
-                requiredAudience,
+                requiredAudience.isEmpty() ? null : new HashSet<>(requiredAudience),
                 null,
-                Collections.emptySet()
+                Collections.emptySet(),
+                null
             );
             claimsVerifier.setMaxClockSkew(clockSkewToleranceSeconds);
             claimsVerifier.verify(claims, null);
@@ -127,10 +130,10 @@ private void validateClaims(SignedJWT jwt) throws ParseException, BadJWTExceptio
     }
 
     private void validateRequiredAudienceAndIssuer(JWTClaimsSet claims) throws BadJWTException {
-        String audience = claims.getAudience().stream().findFirst().orElse("");
+        List<String> audience = claims.getAudience();
         String issuer = claims.getIssuer();
 
-        if (!Strings.isNullOrEmpty(requiredAudience) && !requiredAudience.equals(audience)) {
+        if (!requiredAudience.isEmpty() && Collections.disjoint(requiredAudience, audience)) {
             throw new BadJWTException("Invalid audience");
         }
 

src/test/java/com/amazon/dlic/auth/http/jwt/HTTPJwtAuthenticatorTest.java

@@ -482,6 +482,33 @@ public void testRequiredAudienceWithIncorrectAudience() {
         Assert.assertNull(credentials);
     }
 
+    @Test
+    public void testRequiredAudienceWithCorrectAtLeastOneAudience() {
+
+        final AuthCredentials credentials = extractCredentialsFromJwtHeader(
+            Settings.builder()
+                .put("signing_key", BaseEncoding.base64().encode(secretKeyBytes))
+                .put("required_audience", "test_audience,test_audience_2"),
+            Jwts.builder().setSubject("Leonard McCoy").setAudience("test_audience_2")
+        );
+
+        Assert.assertNotNull(credentials);
+        Assert.assertEquals("Leonard McCoy", credentials.getUsername());
+    }
+
+    @Test
+    public void testRequiredAudienceWithInCorrectAtLeastOneAudience() {
+
+        final AuthCredentials credentials = extractCredentialsFromJwtHeader(
+            Settings.builder()
+                .put("signing_key", BaseEncoding.base64().encode(secretKeyBytes))
+                .put("required_audience", "test_audience,test_audience_2"),
+            Jwts.builder().setSubject("Leonard McCoy").setAudience("wrong_audience")
+        );
+
+        Assert.assertNull(credentials);
+    }
+
     @Test
     public void testRequiredIssuerWithCorrectAudience() {
 

src/test/java/com/amazon/dlic/auth/http/jwt/keybyoidc/HTTPJwtKeyByOpenIdConnectAuthenticatorTest.java

@@ -118,6 +118,28 @@ public void jwksNotMatchingRequiredIssuerInClaimTest() {
         Assert.assertNull(creds);
     }
 
+    @Test
+    public void jwksMatchAtLeastOneRequiredAudienceInClaimTest() {
+        Settings settings = Settings.builder()
+            .put("openid_connect_url", mockIdpServer.getDiscoverUri())
+            .put("required_issuer", TestJwts.TEST_ISSUER)
+            .put("required_audience", TestJwts.TEST_AUDIENCE + ",another_audience")
+            .build();
+
+        HTTPJwtKeyByOpenIdConnectAuthenticator jwtAuth = new HTTPJwtKeyByOpenIdConnectAuthenticator(settings, null);
+
+        AuthCredentials creds = jwtAuth.extractCredentials(
+            new FakeRestRequest(ImmutableMap.of("Authorization", TestJwts.MC_COY_SIGNED_OCT_1), new HashMap<>()).asSecurityRequest(),
+            null
+        );
+
+        Assert.assertNotNull(creds);
+        Assert.assertEquals(TestJwts.MCCOY_SUBJECT, creds.getUsername());
+        Assert.assertEquals(List.of(TestJwts.TEST_AUDIENCE).toString(), creds.getAttributes().get("attr.jwt.aud"));
+        Assert.assertEquals(0, creds.getBackendRoles().size());
+        Assert.assertEquals(4, creds.getAttributes().size());
+    }
+
     @Test
     public void jwksMissingRequiredAudienceInClaimTest() {
         Settings settings = Settings.builder()