Merge pull request 'fix(apigatewayv2): verify tokens from Floci's own Cognito pools in-process' (#10) from fix/apigatewayv2-local-cognito-issuer into main

Reviewed-on: #10

src/main/java/io/github/hectorvent/floci/services/apigatewayv2/JwtSignatureVerifier.java

@@ -4,8 +4,10 @@ import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.github.hectorvent.floci.config.EmulatorConfig;
 import io.github.hectorvent.floci.core.common.SsrfProtection;
+import io.github.hectorvent.floci.services.cognito.CognitoService;
 import jakarta.annotation.PreDestroy;
 import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.inject.Instance;
 import jakarta.inject.Inject;
 import org.apache.hc.client5.http.DnsResolver;
 import org.apache.hc.client5.http.SystemDefaultDnsResolver;
@@ -37,6 +39,7 @@ import java.util.Base64;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
 
 /**
  * Verifies the RS256 signature of a token presented to an HTTP API v2 JWT authorizer, the same
@@ -66,8 +69,27 @@ public class JwtSignatureVerifier implements AutoCloseable {
     private final CloseableHttpClient httpClient;
     private final boolean allowPrivateNetworkTargets;
     private final Map<String, CachedJwks> jwksCache = new ConcurrentHashMap<>();
+    private Function<String, Optional<Map<String, RSAPublicKey>>> localIssuerKeys = issuer -> Optional.empty();
 
+    /**
+     * An issuer that is one of this emulator's own Cognito pools is served at Floci's base URL, which
+     * is plain HTTP on a hostname such as {@code localhost} or a Compose service name, so the HTTPS
+     * and address rules below would refuse to fetch it. Its keys are read from the pool instead:
+     * they are the same keys the pool publishes at its JWKS URL.
+     */
     @Inject
+    public JwtSignatureVerifier(ObjectMapper objectMapper, EmulatorConfig config, Instance<CognitoService> cognito) {
+        this(objectMapper, config);
+        withLocalIssuerKeys(issuer -> cognito.isResolvable()
+                ? cognito.get().localIssuerKeys(issuer) : Optional.empty());
+    }
+
+    /** Where the keys of in-process issuers come from; package-private so tests can stand one in. */
+    JwtSignatureVerifier withLocalIssuerKeys(Function<String, Optional<Map<String, RSAPublicKey>>> localIssuerKeys) {
+        this.localIssuerKeys = localIssuerKeys;
+        return this;
+    }
+
     public JwtSignatureVerifier(ObjectMapper objectMapper, EmulatorConfig config) {
         this(objectMapper, SystemDefaultDnsResolver.INSTANCE,
                 config.security().allowPrivateJwtTargets());
@@ -162,6 +184,10 @@ public class JwtSignatureVerifier implements AutoCloseable {
     }
 
     private RSAPublicKey resolveKey(String issuer, String kid) throws JwtVerificationException {
+        Optional<Map<String, RSAPublicKey>> local = localIssuerKeys.apply(issuer);
+        if (local.isPresent()) {
+            return local.get().get(kid);
+        }
         CachedJwks cached = jwksCache.get(issuer);
         if (cached != null && !cached.isExpired()) {
             RSAPublicKey key = cached.keysByKid().get(kid);

src/main/java/io/github/hectorvent/floci/services/cognito/CognitoAuthFlowHandler.java

@@ -291,7 +291,10 @@ final class CognitoAuthFlowHandler {
             if (!"UserNotFoundException".equals(ae.getErrorCode())) throw ae;
             user = tryUserMigration(pool, client, username, password, null, clientMetadata,
                     "UserMigration_Authentication");
-            if (user == null) throw ae;
+            if (user == null) {
+                if (!CognitoService.hidesUserExistence(client)) throw ae;
+                throw new AwsException("NotAuthorizedException", "Incorrect username or password", 400);
+            }
         }
 
         firePreAuthentication(pool, client, user, null, clientMetadata, false);

src/main/java/io/github/hectorvent/floci/services/cognito/CognitoService.java

@@ -2592,7 +2592,8 @@ public class CognitoService implements ResourceProvider {
             String confirmationCode) {
         UserPool pool = poolStore.get(userPoolId)
                 .orElseThrow(() -> userPoolNotFound(userPoolId));
-        CognitoUser user = adminGetUser(client.getUserPoolId(), username);
+        CognitoUser user = userForClientOrNull(client, username);
+        if (user == null) throw codeMismatch();
         if (verificationCodeService != null && isSignUpConfirmationEnabled(pool)) {
             try {
                 verificationCodeService.consume(client.getUserPoolId(), user.getUsername(),
@@ -2636,7 +2637,8 @@ public class CognitoService implements ResourceProvider {
                 .orElseThrow(() -> new AwsException("ResourceNotFoundException", "Client not found",
                         400));
         UserPool pool = describeUserPool(client.getUserPoolId());
-        CognitoUser user = adminGetUser(client.getUserPoolId(), username);
+        CognitoUser user = userForClientOrNull(client, username);
+        if (user == null) return simulatedCodeDelivery(username);
         if (!"UNCONFIRMED".equals(user.getUserStatus())) {
             throw new AwsException("NotAuthorizedException",
                     "User cannot be confirmed. Current status is " + user.getUserStatus(), 400);
@@ -2774,7 +2776,8 @@ public class CognitoService implements ResourceProvider {
     public Map<String, Object> forgotPassword(String clientId, String username) {
         UserPoolClient client = clientStore.get(clientId)
                 .orElseThrow(() -> new AwsException("ResourceNotFoundException", "Client not found", 400));
-        CognitoUser user = adminGetUser(client.getUserPoolId(), username);
+        CognitoUser user = userForClientOrNull(client, username);
+        if (user == null) return new LinkedHashMap<>(simulatedCodeDelivery(username));
         UserPool pool = describeUserPool(client.getUserPoolId());
         ensureVerificationWiring();
         DeliveryTarget deliveryTarget = resolveForgotPasswordDeliveryTarget(pool, user);
@@ -2800,7 +2803,8 @@ public class CognitoService implements ResourceProvider {
     public void confirmForgotPassword(String clientId, String username, String confirmationCode, String newPassword) {
         UserPoolClient client = clientStore.get(clientId)
                 .orElseThrow(() -> new AwsException("ResourceNotFoundException", "Client not found", 400));
-        CognitoUser user = adminGetUser(client.getUserPoolId(), username);
+        CognitoUser user = userForClientOrNull(client, username);
+        if (user == null) throw codeMismatch();
         ensureVerificationWiring();
         try {
             verificationCodeService.consume(client.getUserPoolId(), user.getUsername(),
@@ -3075,6 +3079,18 @@ public class CognitoService implements ResourceProvider {
         return overrideId;
     }
 
+    /**
+     * The signing keys, by kid, of this emulator's own pool that {@code issuer} names exactly, so a
+     * JWT authorizer can verify the pool's tokens in-process; empty for every other issuer.
+     */
+    public Optional<Map<String, RSAPublicKey>> localIssuerKeys(String issuer) {
+        if (issuer == null) return Optional.empty();
+        String trimmed = issuer.replaceAll("/+$", "");
+        String poolId = trimmed.substring(trimmed.lastIndexOf('/') + 1);
+        if (poolId.isEmpty() || !getIssuer(poolId).equals(trimmed)) return Optional.empty();
+        return poolStore.get(poolId).map(pool -> Map.of(getSigningKeyId(pool), getSigningPublicKey(pool)));
+    }
+
     public String getJwksUri(String poolId) {
         return getIssuer(poolId) + "/.well-known/jwks.json";
     }
@@ -4446,10 +4462,38 @@ public class CognitoService implements ResourceProvider {
         }
     }
 
+    /**
+     * Whether the app client hides which usernames exist (PreventUserExistenceErrors=ENABLED). Real Cognito then
+     * answers for an unknown user exactly as for a real one: a failed sign-in is "Incorrect username or password",
+     * a code request reports a simulated delivery and a code check reports a wrong code. Unset means LEGACY.
+     */
+    static boolean hidesUserExistence(UserPoolClient client) {
+        return "ENABLED".equals(client.getPreventUserExistenceErrors());
+    }
+
+    /** The user, or null when it does not exist and the client hides that; otherwise UserNotFoundException. */
+    private CognitoUser userForClientOrNull(UserPoolClient client, String username) {
+        try {
+            return adminGetUser(client.getUserPoolId(), username);
+        } catch (AwsException e) {
+            if ("UserNotFoundException".equals(e.getErrorCode()) && hidesUserExistence(client)) return null;
+            throw e;
+        }
+    }
+
+    private Map<String, String> simulatedCodeDelivery(String username) {
+        return username != null && username.contains("@")
+                ? Map.of("AttributeName", "email", "DeliveryMedium", "EMAIL", "Destination", maskEmail(username))
+                : Map.of("AttributeName", "phone_number", "DeliveryMedium", "SMS", "Destination", "+*******0000");
+    }
+
+    private static AwsException codeMismatch() {
+        return new AwsException("CodeMismatchException", "Invalid verification code provided, please try again.", 400);
+    }
+
     private AwsException mapVerificationCodeException(VerificationCodeException e) {
         return switch (e.getKind()) {
-            case MISMATCH, NOT_FOUND -> new AwsException("CodeMismatchException",
-                    "Invalid verification code provided, please try again.", 400);
+            case MISMATCH, NOT_FOUND -> codeMismatch();
             case EXPIRED -> new AwsException("ExpiredCodeException",
                     "Invalid code provided, please request a code again.", 400);
             case RATE_LIMIT -> new AwsException("LimitExceededException",

src/test/java/io/github/hectorvent/floci/services/apigatewayv2/JwtSignatureVerifierTest.java

@@ -98,6 +98,26 @@ class JwtSignatureVerifierTest {
         verifier.verify(token, issuer); // does not throw
     }
 
+    @Test
+    void verifiesAnInProcessIssuerWithoutFetchingIt() throws Exception {
+        // Floci's own Cognito issuer: plain HTTP on a hostname, which the strict fetch rules refuse.
+        String localIssuer = "http://floci:4566/us-east-1_local";
+        strictVerifier.withLocalIssuerKeys(candidate -> candidate.equals(localIssuer)
+                ? java.util.Optional.of(Map.of("test-key-1", publicKey)) : java.util.Optional.empty());
+
+        assertDoesNotThrow(() -> strictVerifier.verify(signToken("test-key-1", privateKey), localIssuer));
+        assertThrows(JwtSignatureVerifier.JwtVerificationException.class,
+                () -> strictVerifier.verify(signToken("other-key", privateKey), localIssuer));
+        KeyPairGenerator gen = KeyPairGenerator.getInstance("RSA");
+        gen.initialize(2048);
+        String forged = signToken("test-key-1", (RSAPrivateKey) gen.generateKeyPair().getPrivate());
+        assertThrows(JwtSignatureVerifier.JwtVerificationException.class,
+                () -> strictVerifier.verify(forged, localIssuer));
+        // Any other plain-HTTP issuer still goes through the strict fetch, and is refused.
+        assertThrows(JwtSignatureVerifier.JwtVerificationException.class,
+                () -> strictVerifier.verify(signToken("test-key-1", privateKey), "http://floci:4566/us-east-1_other"));
+    }
+
     @Test
     void rejectsATokenSignedWithADifferentKey() throws Exception {
         KeyPairGenerator gen = KeyPairGenerator.getInstance("RSA");

src/test/java/io/github/hectorvent/floci/services/cognito/CognitoServiceTest.java

@@ -373,6 +373,63 @@ class CognitoServiceTest {
                 null, null, List.of(), null, null);
     }
 
+    @Nested
+    class PreventUserExistenceErrors {
+
+        private UserPoolClient client(UserPool pool, String preventUserExistenceErrors) {
+            return service.createUserPoolClient(pool.getId(), "existence-client", false, false, List.of(), List.of(),
+                    null, List.of(), null, List.of("ALLOW_USER_PASSWORD_AUTH"), null, null, List.of(),
+                    preventUserExistenceErrors, List.of(), null, null, null, List.of(), null, null);
+        }
+
+        @Test
+        void enabledAnswersAnUnknownUserLikeAWrongPassword() {
+            UserPool pool = createPoolAndUser();
+            UserPoolClient client = client(pool, "ENABLED");
+
+            AwsException unknown = assertThrows(AwsException.class, () -> service.initiateAuth(client.getClientId(),
+                    "USER_PASSWORD_AUTH", Map.of("USERNAME", "nobody", "PASSWORD", "Perm1234!")));
+            AwsException wrongPassword = assertThrows(AwsException.class, () -> service.initiateAuth(client.getClientId(),
+                    "USER_PASSWORD_AUTH", Map.of("USERNAME", "alice", "PASSWORD", "Wrong1234!")));
+
+            assertEquals("NotAuthorizedException", unknown.getErrorCode());
+            assertEquals(wrongPassword.getErrorCode(), unknown.getErrorCode());
+            assertEquals(wrongPassword.getMessage(), unknown.getMessage());
+        }
+
+        @Test
+        void enabledSimulatesCodeDeliveryAndRejectsCodesForAnUnknownUser() {
+            UserPool pool = createPoolAndUser();
+            UserPoolClient client = client(pool, "ENABLED");
+
+            assertEquals(Map.of("AttributeName", "email", "DeliveryMedium", "EMAIL", "Destination", "n***@e***"),
+                    service.forgotPassword(client.getClientId(), "nobody@example.com"));
+            assertEquals("EMAIL", service.resendConfirmationCode(client.getClientId(), "nobody@example.com")
+                    .get("DeliveryMedium"));
+            assertEquals("CodeMismatchException", assertThrows(AwsException.class, () ->
+                    service.confirmForgotPassword(client.getClientId(), "nobody@example.com", "123456", "Perm1234!"))
+                    .getErrorCode());
+            assertEquals("CodeMismatchException", assertThrows(AwsException.class, () ->
+                    service.confirmSignUp(client.getClientId(), "nobody@example.com", "123456")).getErrorCode());
+            assertThrows(AwsException.class, () -> service.adminGetUser(pool.getId(), "nobody@example.com"),
+                    "no user is created along the way");
+        }
+
+        @Test
+        void legacyAndUnsetStillReportUserNotFound() {
+            UserPool pool = createPoolAndUser();
+            for (String setting : new String[] {"LEGACY", null}) {
+                UserPoolClient client = client(pool, setting);
+
+                assertEquals("UserNotFoundException", assertThrows(AwsException.class, () -> service.initiateAuth(
+                        client.getClientId(), "USER_PASSWORD_AUTH", Map.of("USERNAME", "nobody", "PASSWORD", "x")))
+                        .getErrorCode());
+                assertEquals("UserNotFoundException", assertThrows(AwsException.class, () ->
+                        service.forgotPassword(client.getClientId(), "nobody")).getErrorCode());
+            }
+        }
+    }
+
     @ParameterizedTest
     @CsvSource({
             "Short1!a",
@@ -1312,6 +1369,22 @@ class CognitoServiceTest {
         assertEquals("http://localhost:4566/custompool", service.getIssuer(pool.getId()));
     }
 
+    @Test
+    void localIssuerKeysServeOnlyThisEmulatorsOwnPoolIssuers() throws Exception {
+        UserPool pool = createPoolAndUser();
+        UserPoolClient client = clientWithFlows(pool, "ALLOW_USER_PASSWORD_AUTH");
+        String token = (String) ((Map<?, ?>) service.initiateAuth(client.getClientId(), "USER_PASSWORD_AUTH",
+                Map.of("USERNAME", "alice", "PASSWORD", "Perm1234!")).get("AuthenticationResult")).get("AccessToken");
+        String kid = MAPPER.readTree(Base64.getUrlDecoder().decode(token.split("\\.")[0])).path("kid").asText();
+
+        Map<String, java.security.interfaces.RSAPublicKey> keys = service.localIssuerKeys(service.getIssuer(pool.getId())).orElseThrow();
+        assertTrue(keys.containsKey(kid), "the key that signed the pool's tokens");
+        assertTrue(service.localIssuerKeys(service.getIssuer(pool.getId()) + "/").isPresent());
+        assertTrue(service.localIssuerKeys("https://cognito-idp.us-east-1.amazonaws.com/" + pool.getId()).isEmpty());
+        assertTrue(service.localIssuerKeys(service.getIssuer("us-east-1_missing")).isEmpty());
+        assertTrue(service.localIssuerKeys(null).isEmpty());
+    }
+
     // =========================================================================
     // Groups
     // =========================================================================