write the file config store with owner-only permissions

tika-pipes/tika-pipes-core/src/main/java/org/apache/tika/pipes/core/config/FileBasedConfigStore.java

@@ -17,10 +17,14 @@
 package org.apache.tika.pipes.core.config;
 
 import java.io.IOException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
+import java.nio.file.attribute.FileAttribute;
+import java.nio.file.attribute.PosixFilePermission;
+import java.nio.file.attribute.PosixFilePermissions;
+import java.util.EnumSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
@@ -41,6 +45,9 @@ public class FileBasedConfigStore implements ConfigStore {
 
     private static final Logger LOG = LoggerFactory.getLogger(FileBasedConfigStore.class);
     private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+    // stored configs carry fetcher/emitter credentials; keep them from other local users
+    private static final Set<PosixFilePermission> OWNER_ONLY =
+            EnumSet.of(PosixFilePermission.OWNER_READ, PosixFilePermission.OWNER_WRITE);
 
     private final Path configFile;
     private final ConcurrentHashMap<String, ExtensionConfig> cache = new ConcurrentHashMap<>();
@@ -150,16 +157,35 @@ private synchronized void loadFromFile() throws IOException {
     }
 
     private synchronized void saveToFile() {
+        Path tempFile = null;
         try {
-            // Write to temp file first, then atomic rename
-            Path tempFile = Paths.get(configFile.toString() + ".tmp");
+            // Write to a unique temp file first, then atomic rename; a unique name keeps
+            // other instances/processes from deleting or recreating it mid-write
+            tempFile = Files.createTempFile(configFile.toAbsolutePath().getParent(),
+                    configFile.getFileName() + ".", ".tmp", ownerOnly());
             OBJECT_MAPPER.writerWithDefaultPrettyPrinter()
                 .writeValue(tempFile.toFile(), cache);
             Files.move(tempFile, configFile, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.ATOMIC_MOVE);
+            tempFile = null;
             LOG.debug("Saved {} configurations to {}", cache.size(), configFile);
         } catch (IOException e) {
             LOG.error("Failed to save configurations to {}", configFile, e);
             throw new RuntimeException("Failed to save config store", e);
+        } finally {
+            if (tempFile != null) {
+                try {
+                    Files.deleteIfExists(tempFile);
+                } catch (IOException e) {
+                    LOG.warn("Failed to delete temp file {}", tempFile, e);
+                }
+            }
         }
     }
+
+    private static FileAttribute<?>[] ownerOnly() {
+        if (FileSystems.getDefault().supportedFileAttributeViews().contains("posix")) {
+            return new FileAttribute<?>[]{PosixFilePermissions.asFileAttribute(OWNER_ONLY)};
+        }
+        return new FileAttribute<?>[0];
+    }
 }

tika-pipes/tika-pipes-core/src/test/java/org/apache/tika/pipes/core/config/ConfigStoreTest.java

@@ -21,8 +21,19 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
+
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.PosixFilePermission;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
 import org.apache.tika.plugins.ExtensionConfig;
 
@@ -112,4 +123,21 @@ public void testLoggingConfigStore() {
 
         assertNull(store.get("nonexistent"));
     }
+
+    @Test
+    public void testFileBasedConfigStoreIsOwnerOnly(@TempDir Path tmp) throws Exception {
+        assumeTrue(FileSystems.getDefault().supportedFileAttributeViews().contains("posix"));
+        Path file = tmp.resolve("store").resolve("config-store.json");
+        FileBasedConfigStore store = new FileBasedConfigStore(file);
+        store.init();
+        store.put("s3", new ExtensionConfig("s3", "s3-fetcher", "{\"secretKey\":\"hunter2\"}"));
+        store.put("http", new ExtensionConfig("http", "http-fetcher", "{\"password\":\"x\"}"));
+
+        Set<PosixFilePermission> perms = Files.getPosixFilePermissions(file);
+        assertEquals(Set.of(PosixFilePermission.OWNER_READ, PosixFilePermission.OWNER_WRITE), perms);
+        try (Stream<Path> siblings = Files.list(file.getParent())) {
+            assertEquals(List.of(file), siblings.collect(Collectors.toList()));
+        }
+        assertEquals("s3-fetcher", new FileBasedConfigStore(file).get("s3").name());
+    }
 }