Watch SSL files instead of directories

docs/changelog/129738.yaml

@@ -0,0 +1,5 @@
+pr: 129738
+summary: Watch SSL files instead of directories
+area: TLS
+type: bug
+issues: []

server/src/main/java/org/elasticsearch/watcher/FileWatcher.java

@@ -57,6 +57,11 @@ public FileWatcher(Path path, boolean checkFileContents) {
         rootFileObserver = new FileObserver(path);
     }
 
+    // For testing
+    public Path getPath() {
+        return path;
+    }
+
     /**
      * Clears any state with the FileWatcher, making all files show up as new
      */

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ssl/SSLConfigurationReloader.java

@@ -22,10 +22,8 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.function.Consumer;
@@ -80,7 +78,7 @@ private static Consumer<SslConfiguration> reloadConsumer(Future<SSLService> futu
     }
 
     /**
-     * Collects all of the directories that need to be monitored for the provided {@link SslConfiguration} instances and ensures that
+     * Collects all of the files that need to be monitored for the provided {@link SslConfiguration} instances and ensures that
      * they are being watched for changes
      */
     private static void startWatching(
@@ -91,8 +89,8 @@ private static void startWatching(
         Map<Path, List<SslConfiguration>> pathToConfigurationsMap = new HashMap<>();
         for (SslConfiguration sslConfiguration : sslConfigurations) {
             final Collection<Path> filesToMonitor = sslConfiguration.getDependentFiles();
-            for (Path directory : directoriesToMonitor(filesToMonitor)) {
-                pathToConfigurationsMap.compute(directory, (path, list) -> {
+            for (Path file : filesToMonitor) {
+                pathToConfigurationsMap.compute(file, (path, list) -> {
                     if (list == null) {
                         list = new ArrayList<>();
                     }
@@ -109,22 +107,11 @@ private static void startWatching(
             try {
                 resourceWatcherService.add(fileWatcher, Frequency.HIGH);
             } catch (IOException | SecurityException e) {
-                logger.error("failed to start watching directory [{}] for ssl configurations [{}] - {}", path, configurations, e);
+                logger.error("failed to start watching file [{}] for ssl configurations [{}] - {}", path, configurations, e);
             }
         });
     }
 
-    /**
-     * Returns a unique set of directories that need to be monitored based on the provided file paths
-     */
-    private static Set<Path> directoriesToMonitor(Iterable<Path> filePaths) {
-        Set<Path> paths = new HashSet<>();
-        for (Path path : filePaths) {
-            paths.add(path.getParent());
-        }
-        return paths;
-    }
-
     private static class ChangeListener implements FileChangesListener {
 
         private final List<SslConfiguration> sslConfigurations;

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ssl/SSLConfigurationReloaderTests.java

@@ -37,6 +37,8 @@
 import org.elasticsearch.test.http.MockWebServer;
 import org.elasticsearch.threadpool.TestThreadPool;
 import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.watcher.FileWatcher;
+import org.elasticsearch.watcher.ResourceWatcher;
 import org.elasticsearch.watcher.ResourceWatcherService;
 import org.junit.After;
 import org.junit.Before;
@@ -66,7 +68,9 @@
 import java.security.cert.CertificateException;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.CyclicBarrier;
 import java.util.concurrent.TimeUnit;
@@ -79,6 +83,7 @@
 import javax.net.ssl.SSLSocket;
 
 import static org.elasticsearch.test.TestMatchers.throwableWithMessage;
+import static org.hamcrest.Matchers.containsInAnyOrder;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.sameInstance;
 
@@ -559,6 +564,38 @@ public void testFailureToReadFileDoesntFail() throws Exception {
         }
     }
 
+    /**
+     * Due to exclusive access entitlements
+     * (see {@link org.elasticsearch.entitlement.runtime.policy.entitlements.FilesEntitlement.FileData#exclusive}),
+     * it is not safe to monitor a directory or any files that are not an explicit part of this SSL configuration.
+     */
+    public void testReloaderOnlyWatchesSpecifiedFiles() throws Exception {
+        final Set<Path> watchedPaths = new HashSet<>();
+        final ResourceWatcherService mockResourceWatcher = Mockito.mock(ResourceWatcherService.class);
+        Mockito.when(mockResourceWatcher.add(Mockito.any(ResourceWatcher.class), Mockito.any(ResourceWatcherService.Frequency.class)))
+            .then(inv -> {
+                final FileWatcher fileWatcher = asInstanceOf(FileWatcher.class, inv.getArguments()[0]);
+                watchedPaths.add(fileWatcher.getPath());
+                return null;
+            });
+
+        final Path tempDir = createTempDir();
+        final Path clientCertPath = tempDir.resolve("testclient.crt");
+        Settings settings = baseKeystoreSettings(tempDir, null).putList(
+            "xpack.security.transport.ssl.certificate_authorities",
+            clientCertPath.toString()
+        ).put("path.home", createTempDir()).build();
+
+        final Environment env = newEnvironment(settings);
+        final Collection<SslConfiguration> configurations = SSLService.getSSLConfigurations(env).values();
+        new SSLConfigurationReloader(ignore -> {}, mockResourceWatcher, configurations);
+
+        assertThat(
+            watchedPaths,
+            containsInAnyOrder(tempDir.resolve("testclient.pem"), tempDir.resolve("testclient.crt"), tempDir.resolve("testclientcert.crt"))
+        );
+    }
+
     private Settings.Builder baseKeystoreSettings(Path tempDir, MockSecureSettings secureSettings) throws IOException {
         final Path keyPath = tempDir.resolve("testclient.pem");
         final Path certPath = tempDir.resolve("testclientcert.crt"); // testclient.crt filename already used in #testPEMTrustReloadException