Handle validation of non expiring tokens in jwt_authn filter (#4007)

Signed-off-by: Vinod <[email protected]>

source/extensions/filters/http/jwt_authn/authenticator.cc

@@ -119,7 +119,9 @@ void AuthenticatorImpl::verify(Http::HeaderMap& headers, Authenticator::Callback
   const auto unix_timestamp = std::chrono::duration_cast<std::chrono::seconds>(
                                   std::chrono::system_clock::now().time_since_epoch())
                                   .count();
-  if (jwt_.exp_ < unix_timestamp) {
+  // NOTE: Service account tokens generally don't have an expiration time (due to being long lived)
+  // and defaulted to 0 by google::jwt_verify library but are still valid.
+  if (jwt_.exp_ > 0 && jwt_.exp_ < unix_timestamp) {
     doneWithStatus(Status::JwtExpired);
     return;
   }

test/extensions/filters/http/jwt_authn/authenticator_test.cc

@@ -164,6 +164,19 @@ TEST_F(AuthenticatorTest, TestInvalidPrefix) {
   auth_->verify(headers, &mock_cb_);
 }
 
+// This test verifies when a JWT is non-expiring without audience specified, JwtAudienceNotAllowed
+// is returned.
+TEST_F(AuthenticatorTest, TestNonExpiringJWT) {
+  EXPECT_CALL(mock_factory_ctx_.cluster_manager_, httpAsyncClientForCluster(_)).Times(0);
+  EXPECT_CALL(mock_cb_, onComplete(_)).WillOnce(Invoke([](const Status& status) {
+    ASSERT_EQ(status, Status::JwtAudienceNotAllowed);
+  }));
+
+  auto headers =
+      Http::TestHeaderMapImpl{{"Authorization", "Bearer " + std::string(NonExpiringToken)}};
+  auth_->verify(headers, &mock_cb_);
+}
+
 // This test verifies when a JWT is expired, JwtExpired status is returned.
 TEST_F(AuthenticatorTest, TestExpiredJWT) {
   EXPECT_CALL(mock_factory_ctx_.cluster_manager_, httpAsyncClientForCluster(_)).Times(0);

test/extensions/filters/http/jwt_authn/test_common.h

@@ -63,6 +63,17 @@ const char GoodToken[] = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwc
                          "EprqSZUzi_ZzzYzqBNVhIJujcNWij7JRra2sXXiSAfKjtxHQoxrX8n4V1ySWJ3_1T"
                          "H_cJcdfS_RKP7YgXRWC0L16PNF5K7iqRqmjKALNe83ZFnFIw";
 
+// Payload:
+// {"iss":"https://example.com","sub":"[email protected]","exp":null}
+const char NonExpiringToken[] =
+    "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwczovL2V4YW1wbGUu"
+    "Y29tIiwic3ViIjoidGVzdEBleGFtcGxlLmNvbSIsImlhdCI6MTUzMzE3NTk0Mn0.OSh-"
+    "AcY9dCUibXiIZzPlTdEsYH8xP3QkCJDesO3LVu4ndgTrxDnNuR3I4_oV4tjtirmLZD3sx"
+    "96wmLiIhOyqj3nipIdf_aQWcmET0XoRqGixOKse5FlHyU_VC1Jj9AlMvSz9zyCvKxMyP0"
+    "CeA-bhI_Qs-I9vBPK8pd-EUOespUqWMQwNdtrOdXLcvF8EA5BV5G2qRGzCU0QJaW0Dpyj"
+    "YF7ZCswRGorc2oMt5duXSp3-L1b9dDrnLwroxUrmQIZz9qvfwdDR-guyYSjKVQu5NJAyy"
+    "sd8XKNzmHqJ2fYhRjc5s7l5nIWTDyBXSdPKQ8cBnfFKoxaRhmMBjdEn9RB7r6A";
+
 // An expired token
 // {"iss":"https://example.com","sub":"[email protected]","aud":"example_service","exp":1205005587}
 const char ExpiredToken[] = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwczovL2V4YW1wbGUu"