Stop restricting read access to the file system

This is just too complicated to get right (on all platforms).

README.md

@@ -1,6 +1,6 @@
 # hermetic-maven-plugin
 
-This Maven plugin configures the Maven build so that tests are executed hermetically, i.e. without access to remote resources and files outside of the project directory. To achieve this the plugin generates a Java 2 security policy and configures a custom security manager. By default the corresponding command line arguments are added to the `argLine` property so that they are picked up by [maven-surefire-plugin](http://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#argLine).
+This Maven plugin configures the Maven build so that tests are executed hermetically, i.e. without access to remote resources. To achieve this the plugin generates a Java 2 security policy and configures a custom security manager. By default the corresponding command line arguments are added to the `argLine` property so that they are picked up by [maven-surefire-plugin](http://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#argLine).
 
 ## Making maven-invoker-plugin executions hermetic
 

pom.xml

@@ -27,7 +27,7 @@
 
     <groupId>com.github.veithen.maven</groupId>
     <artifactId>hermetic-maven-plugin</artifactId>
-    <version>0.7.2-SNAPSHOT</version>
+    <version>0.8.0-SNAPSHOT</version>
     <packaging>maven-plugin</packaging>
 
     <url>https://github.com/veithen/hermetic-maven-plugin</url>

src/it/simple/src/test/java/PermissionTest.java

@@ -144,13 +144,6 @@ public void testLocalURLAccess() throws Exception {
         }
     }
 
-    @Test
-    public void testFileSystemAccess() throws Exception {
-        assertThrows(
-                SecurityException.class,
-                () -> new File(System.getProperty("user.home"), "somefile").listFiles());
-    }
-
     @Test
     public void testUserHomeDirectoryCheck() throws Exception {
         new File(System.getProperty("user.home")).isDirectory();

src/main/java/com/github/veithen/maven/hermetic/GeneratePolicyMojo.java

@@ -35,11 +35,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Properties;
-import java.util.regex.Pattern;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
-import org.apache.maven.artifact.Artifact;
 import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.AbstractMojo;
 import org.apache.maven.plugin.MojoExecution;
@@ -62,17 +58,6 @@
         defaultPhase = LifecyclePhase.GENERATE_TEST_RESOURCES,
         threadSafe = true)
 public final class GeneratePolicyMojo extends AbstractMojo {
-    private static final String[] defaultSafeMethods = {
-        "org.apache.tools.ant.types.Path.addExisting",
-        "org.apache.tools.ant.util.JavaEnvUtils.getJdkExecutable",
-    };
-
-    private static final String[] miscFiles = {
-        // The Maven version distributed with RHEL uses a modified Apache HttpClient that reads this
-        // file.
-        "/usr/share/publicsuffix/effective_tld_names.dat",
-    };
-
     @Parameter(property = "project", readonly = true, required = true)
     private MavenProject project;
 
@@ -99,9 +84,6 @@ public final class GeneratePolicyMojo extends AbstractMojo {
     @Parameter(defaultValue = "false", required = true)
     private boolean allowExec;
 
-    @Parameter(defaultValue = "false", required = true)
-    private boolean allowCrossProjectAccess;
-
     @Parameter(defaultValue = "argLine", required = true)
     private String property;
 
@@ -111,16 +93,6 @@ public final class GeneratePolicyMojo extends AbstractMojo {
     @Parameter(defaultValue = "false", required = true)
     private boolean generatePolicyOnly;
 
-    private static boolean isDescendant(File dir, File path) {
-        do {
-            if (path.equals(dir)) {
-                return true;
-            }
-            path = path.getParentFile();
-        } while (path != null);
-        return false;
-    }
-
     @Override
     public void execute() throws MojoExecutionException, MojoFailureException {
         Log log = getLog();
@@ -129,79 +101,11 @@ public void execute() throws MojoExecutionException, MojoFailureException {
             return;
         }
 
-        File projectDir = project.getBasedir();
-        if (allowCrossProjectAccess) {
-            File dir = projectDir;
-            while ((dir = dir.getParentFile()) != null) {
-                if (new File(dir, "pom.xml").exists()) {
-                    projectDir = dir;
-                }
-            }
-        }
-
         outputFile.getParentFile().mkdirs();
         try (Writer out = new OutputStreamWriter(new FileOutputStream(outputFile), "utf-8")) {
             PolicyWriter writer = new PolicyWriter(out, log);
             writer.start();
 
-            // If the JAVA_HOME environment variable is set to a symlink, then the java.home system
-            // property will point to the target of the symlink, so we need to use the original
-            // JAVA_HOME value.
-            String javaHomeString = System.getenv("JAVA_HOME");
-            if (javaHomeString == null) {
-                javaHomeString = System.getProperty("java.home");
-            }
-            File javaHome = new File(javaHomeString);
-            File jdkHome = javaHome.getName().equals("jre") ? javaHome.getParentFile() : javaHome;
-            if (log.isDebugEnabled()) {
-                log.debug("JDK home is " + jdkHome);
-            }
-            writer.generateDirPermissions(jdkHome, Integer.MAX_VALUE, false);
-            String extDirs = System.getProperty("java.ext.dirs");
-            if (extDirs != null) {
-                List<File> dirs =
-                        Stream.of(extDirs.split(Pattern.quote(File.pathSeparator)))
-                                .map(File::new)
-                                .filter(dir -> !isDescendant(jdkHome, dir))
-                                .collect(Collectors.toList());
-                for (File dir : dirs) {
-                    writer.generateDirPermissions(dir, 1, false);
-                }
-            }
-            writer.generateDirPermissions(
-                    new File(System.getProperty("maven.home")), Integer.MAX_VALUE, false);
-            writer.generateDirPermissions(
-                    new File(session.getSettings().getLocalRepository()), 0, false);
-            writer.generateDirPermissions(projectDir, 0, false);
-            writer.writePermission(
-                    new FilePermission(
-                            session.getRequest().getUserToolchainsFile().getAbsolutePath(),
-                            "read"));
-            for (MavenProject project : session.getProjects()) {
-                File file = project.getArtifact().getFile();
-                if (file != null) {
-                    writer.writePermission(new FilePermission(file.getAbsolutePath(), "read"));
-                }
-                for (Artifact attachedArtifact : project.getAttachedArtifacts()) {
-                    writer.writePermission(
-                            new FilePermission(
-                                    attachedArtifact.getFile().getAbsolutePath(), "read"));
-                }
-            }
-            for (String dir :
-                    new String[] {
-                        project.getBuild().getDirectory(), System.getProperty("java.io.tmpdir")
-                    }) {
-                writer.generateDirPermissions(new File(dir), 0, true);
-            }
-            // Some code (like maven-bundle-plugin) uses File#isDirectory() on the home directory.
-            // Allow this, but don't allow access to other files.
-            writer.writePermission(new FilePermission(System.getProperty("user.home"), "read"));
-            for (String file : miscFiles) {
-                if (new File(file).exists()) {
-                    writer.writePermission(new FilePermission(file, "read"));
-                }
-            }
             writer.writePermission(
                     new SocketPermission("localhost", "connect,listen,accept,resolve"));
             for (NetworkInterface iface :
@@ -215,8 +119,18 @@ public void execute() throws MojoExecutionException, MojoFailureException {
                     }
                 }
             }
-            if (allowExec) {
-                writer.writePermission(new FilePermission("<<ALL FILES>>", "execute"));
+            writer.writePermission(
+                    new FilePermission(
+                            "<<ALL FILES>>",
+                            allowExec ? "read,readlink,execute" : "read,readlink"));
+            for (String dir :
+                    new String[] {
+                        project.getBuild().getDirectory(), System.getProperty("java.io.tmpdir")
+                    }) {
+                writer.writePermission(new FilePermission(dir, "read,readlink,write"));
+                writer.writePermission(
+                        new FilePermission(
+                                new File(dir, "-").toString(), "read,readlink,write,delete"));
             }
             writer.end();
         } catch (IOException ex) {
@@ -259,11 +173,9 @@ public void execute() throws MojoExecutionException, MojoFailureException {
 
             args.add("-Xbootclasspath/a:" + securityManagerJarFile.toString());
             args.add("-Djava.security.manager=com.github.veithen.hermetic.HermeticSecurityManager");
-            List<String> allSafeMethods = new ArrayList<>(Arrays.asList(defaultSafeMethods));
             if (safeMethods != null) {
-                allSafeMethods.addAll(Arrays.asList(safeMethods));
+                args.add("-Dhermetic.safeMethods=" + String.join(",", Arrays.asList(safeMethods)));
             }
-            args.add("-Dhermetic.safeMethods=" + String.join(",", allSafeMethods));
         }
         // "==" sets the policy instead of adding additional permissions.
         args.add("-Djava.security.policy==" + outputFile.getAbsolutePath().replace('\\', '/'));

src/main/java/com/github/veithen/maven/hermetic/PolicyWriter.java

@@ -19,8 +19,6 @@
  */
 package com.github.veithen.maven.hermetic;
 
-import java.io.File;
-import java.io.FilePermission;
 import java.io.IOException;
 import java.io.Writer;
 import java.security.Permission;
@@ -70,22 +68,6 @@ void writePermission(Permission permission) throws IOException {
                 actions.isEmpty() ? null : actions);
     }
 
-    void generateDirPermissions(File dir, int maxDepth, boolean allowWrite) throws IOException {
-        String rootActions = allowWrite ? "read,readlink,write" : "read,readlink";
-        String actions = allowWrite ? "read,readlink,write,delete" : "read,readlink";
-        for (PathSpec pathSpec :
-                PathUtil.enumeratePaths(dir.getAbsoluteFile().toPath(), maxDepth)) {
-            writePermission(
-                    new FilePermission(
-                            pathSpec.path().toString(),
-                            pathSpec.depth() == 0 ? rootActions : actions));
-            if (pathSpec.directory()) {
-                writePermission(
-                        new FilePermission(pathSpec.path().resolve("-").toString(), actions));
-            }
-        }
-    }
-
     void end() throws IOException {
         out.write("};\n");
     }