Forbid Files.isHidden.

As Robert pointed out on #12465, it has the undesirable property of relying on
the operating system. So it would be better to use a simple rule such as
checking whether the file name starts with a dot.

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataCreateIndexService.java

@@ -49,6 +49,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.component.AbstractComponent;
 import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.io.FileSystemUtils;
 import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.settings.Settings;
@@ -465,7 +466,7 @@ public class MetaDataCreateIndexService extends AbstractComponent {
         try (DirectoryStream<Path> stream = Files.newDirectoryStream(mappingsDir)) {
             for (Path mappingFile : stream) {
                 final String fileName = mappingFile.getFileName().toString();
-                if (Files.isHidden(mappingFile)) {
+                if (FileSystemUtils.isHidden(mappingFile)) {
                     continue;
                 }
                 int lastDotIndex = fileName.lastIndexOf('.');

core/src/main/java/org/elasticsearch/common/io/FileSystemUtils.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.common.io;
 
 import com.google.common.collect.Iterators;
+
 import org.apache.lucene.util.IOUtils;
 import org.elasticsearch.common.logging.ESLogger;
 
@@ -84,6 +85,20 @@ public final class FileSystemUtils {
         return false;
     }
 
+    /**
+     * Check whether the file denoted by the given path is hidden.
+     * In practice, this will check if the file name starts with a dot.
+     * This should be preferred to {@link Files#isHidden(Path)} as this
+     * does not depend on the operating system.
+     */
+    public static boolean isHidden(Path path) {
+        Path fileName = path.getFileName();
+        if (fileName == null) {
+            return false;
+        }
+        return fileName.toString().startsWith(".");
+    }
+
     /**
      * Appends the path to the given base and strips N elements off the path if strip is > 0.
      */
@@ -334,4 +349,5 @@ public final class FileSystemUtils {
             return Iterators.toArray(stream.iterator(), Path.class);
         }
     }
+
 }

core/src/main/java/org/elasticsearch/http/HttpServer.java

@@ -23,6 +23,7 @@ import com.google.common.collect.ImmutableMap;
 
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
 import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.io.FileSystemUtils;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.env.Environment;
 import org.elasticsearch.node.service.NodeService;
@@ -183,7 +184,7 @@ public class HttpServer extends AbstractLifecycleComponent<HttpServer> {
         Path file = siteFile.resolve(sitePath);
 
         // return not found instead of forbidden to prevent malicious requests to find out if files exist or dont exist
-        if (!Files.exists(file) || Files.isHidden(file) || !file.toAbsolutePath().normalize().startsWith(siteFile.toAbsolutePath().normalize())) {
+        if (!Files.exists(file) || FileSystemUtils.isHidden(file) || !file.toAbsolutePath().normalize().startsWith(siteFile.toAbsolutePath().normalize())) {
             channel.sendResponse(new BytesRestResponse(NOT_FOUND));
             return;
         }
@@ -197,7 +198,7 @@ public class HttpServer extends AbstractLifecycleComponent<HttpServer> {
             }
             // We don't serve dir but if index.html exists in dir we should serve it
             file = file.resolve("index.html");
-            if (!Files.exists(file) || Files.isHidden(file) || !Files.isRegularFile(file)) {
+            if (!Files.exists(file) || FileSystemUtils.isHidden(file) || !Files.isRegularFile(file)) {
                 channel.sendResponse(new BytesRestResponse(FORBIDDEN));
                 return;
             }

core/src/main/java/org/elasticsearch/plugins/PluginsService.java

@@ -23,7 +23,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 
 import org.elasticsearch.ElasticsearchException;
-import org.elasticsearch.Version;
 import org.elasticsearch.action.admin.cluster.node.info.PluginsInfo;
 import org.elasticsearch.bootstrap.Bootstrap;
 import org.elasticsearch.bootstrap.JarHell;
@@ -33,6 +32,7 @@ import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.component.AbstractComponent;
 import org.elasticsearch.common.component.LifecycleComponent;
 import org.elasticsearch.common.inject.Module;
+import org.elasticsearch.common.io.FileSystemUtils;
 import org.elasticsearch.common.logging.ESLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.settings.Settings;
@@ -40,7 +40,6 @@ import org.elasticsearch.env.Environment;
 
 import java.io.Closeable;
 import java.io.IOException;
-import java.io.InputStream;
 import java.lang.reflect.Method;
 import java.net.URL;
 import java.net.URLClassLoader;
@@ -54,7 +53,6 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Properties;
 import java.util.Set;
 
 import static org.elasticsearch.common.io.FileSystemUtils.isAccessibleDirectory;
@@ -312,7 +310,7 @@ public class PluginsService extends AbstractComponent {
         try (DirectoryStream<Path> stream = Files.newDirectoryStream(pluginsDirectory)) {
             for (Path plugin : stream) {
                 try {
-                    if (Files.isHidden(plugin)) {
+                    if (FileSystemUtils.isHidden(plugin)) {
                         logger.trace("--- skip hidden plugin file[{}]", plugin.toAbsolutePath());
                         continue;
                     }

core/src/test/java/org/elasticsearch/common/io/FileSystemUtilsTests.java

@@ -32,6 +32,7 @@ import java.net.URISyntaxException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Arrays;
 
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertFileExists;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertFileNotExists;
@@ -173,4 +174,39 @@ public class FileSystemUtilsTests extends ElasticsearchTestCase {
         assertEquals(FileSystemUtils.append(PathUtils.get("/foo/bar"), PathUtils.get("/hello/world/this_is/awesome"), 1),
                 PathUtils.get("/foo/bar/world/this_is/awesome"));
     }
+
+    public void testIsHidden() {
+        for (String p : Arrays.asList(
+                "/",
+                "foo",
+                "/foo",
+                "foo.bar",
+                "/foo.bar",
+                "foo/bar",
+                "foo/./bar",
+                "foo/../bar",
+                "/foo/./bar",
+                "/foo/../bar"
+                )) {
+            Path path = PathUtils.get(p);
+            assertFalse(FileSystemUtils.isHidden(path));
+        }
+        for (String p : Arrays.asList(
+                ".hidden",
+                ".hidden.ext",
+                "/.hidden",
+                "/.hidden.ext",
+                "foo/.hidden",
+                "foo/.hidden.ext",
+                "/foo/.hidden",
+                "/foo/.hidden.ext",
+                ".",
+                "..",
+                "foo/.",
+                "foo/.."
+                )) {
+            Path path = PathUtils.get(p);
+            assertTrue(FileSystemUtils.isHidden(path));
+        }
+    }
 }

dev-tools/src/main/resources/forbidden/all-signatures.txt

@@ -61,3 +61,5 @@ java.io.ObjectOutputStream
 java.io.ObjectOutput
 java.io.ObjectInputStream
 java.io.ObjectInput
+
+java.nio.file.Files#isHidden(java.nio.file.Path) @ Dependent on the operating system, use FileSystemUtils.isHidden instead