initial firewall implementation to fix #8939

3 files changed, 266 insertions, 0 deletions

diff --git a/app/src/main/java/de/blinkt/openvpn/core/OpenVPNService.java b/app/src/main/java/de/blinkt/openvpn/core/OpenVPNService.java
index 0863cc8e..724fd0fd 100644
--- a/app/src/main/java/de/blinkt/openvpn/core/OpenVPNService.java
+++ b/app/src/main/java/de/blinkt/openvpn/core/OpenVPNService.java
@@ -47,6 +47,7 @@ import de.blinkt.openvpn.core.connection.Obfs4Connection;
 import se.leap.bitmaskclient.R;
 import se.leap.bitmaskclient.VpnNotificationManager;
 import se.leap.bitmaskclient.pluggableTransports.Shapeshifter;
+import se.leap.bitmaskclient.utils.FirewallHelper;
 
 import static de.blinkt.openvpn.core.ConnectionStatus.LEVEL_CONNECTED;
 import static de.blinkt.openvpn.core.ConnectionStatus.LEVEL_WAITING_FOR_USER_INPUT;
@@ -89,6 +90,7 @@ public class OpenVPNService extends VpnService implements StateListener, Callbac
     private Runnable mOpenVPNThread;
     private VpnNotificationManager notificationManager;
     private Shapeshifter shapeshifter;
+    private FirewallHelper firewallHelper;
 
     private static final int PRIORITY_MIN = -2;
     private static final int PRIORITY_DEFAULT = 0;
@@ -192,6 +194,7 @@ public class OpenVPNService extends VpnService implements StateListener, Callbac
                 VpnStatus.removeStateListener(this);
             }
         }
+        firewallHelper.shutdownFirewall();
     }
 
     private boolean runningOnAndroidTV() {
@@ -446,6 +449,8 @@ public class OpenVPNService extends VpnService implements StateListener, Callbac
             mProcessThread.start();
         }
 
+        firewallHelper.startFirewall();
+
         new Handler(getMainLooper()).post(() -> {
             if (mDeviceStateReceiver != null) {
                 unregisterDeviceStateReceiver();
@@ -513,6 +518,7 @@ public class OpenVPNService extends VpnService implements StateListener, Callbac
         super.onCreate();
         notificationManager = new VpnNotificationManager(this, this);
         notificationManager.createOpenVpnNotificationChannel();
+        firewallHelper = new FirewallHelper();
     }
 
     @Override
diff --git a/app/src/main/java/se/leap/bitmaskclient/utils/Cmd.java b/app/src/main/java/se/leap/bitmaskclient/utils/Cmd.java
new file mode 100644
index 00000000..a72658a4
--- /dev/null
+++ b/app/src/main/java/se/leap/bitmaskclient/utils/Cmd.java
@@ -0,0 +1,93 @@
+/**
+ * Copyright (c) 2019 LEAP Encryption Access Project and contributers
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package se.leap.bitmaskclient.utils;
+
+import android.support.annotation.WorkerThread;
+import android.util.Log;
+
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+
+public class Cmd {
+
+    private static final String TAG = Cmd.class.getSimpleName();
+
+    @WorkerThread
+    public static int runBlockingCmd(String[] cmds, StringBuilder log) throws Exception {
+        return runCmd(cmds, log, true);
+    }
+
+    @WorkerThread
+    private static int runCmd(String[] cmds, StringBuilder log,
+                       boolean waitFor) throws Exception {
+
+        int exitCode = -1;
+        Process proc = Runtime.getRuntime().exec("sh");
+        OutputStreamWriter out = new OutputStreamWriter(proc.getOutputStream());
+
+        try {
+            for (String cmd : cmds) {
+                Log.d(TAG, "executing CMD: " + cmd);
+                out.write(cmd);
+                out.write("\n");
+            }
+
+            out.flush();
+            out.write("exit\n");
+            out.flush();
+        } catch (IOException e) {
+            e.printStackTrace();
+        } finally {
+            out.close();
+        }
+
+        if (waitFor) {
+            // Consume the "stdout"
+            InputStreamReader reader = new InputStreamReader(proc.getInputStream());
+            readToLogString(reader, log);
+
+            // Consume the "stderr"
+            reader = new InputStreamReader(proc.getErrorStream());
+            readToLogString(reader, log);
+
+            try {
+                exitCode = proc.waitFor();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+
+        return exitCode;
+    }
+
+    private static void readToLogString(InputStreamReader reader, StringBuilder log) throws IOException {
+        final char buf[] = new char[10];
+        int read = 0;
+        try {
+            while ((read = reader.read(buf)) != -1) {
+                if (log != null)
+                    log.append(buf, 0, read);
+            }
+        } catch (IOException e) {
+            reader.close();
+            throw new IOException(e);
+        }
+        reader.close();
+    }
+}
diff --git a/app/src/main/java/se/leap/bitmaskclient/utils/FirewallHelper.java b/app/src/main/java/se/leap/bitmaskclient/utils/FirewallHelper.java
new file mode 100644
index 00000000..43a5296f
--- /dev/null
+++ b/app/src/main/java/se/leap/bitmaskclient/utils/FirewallHelper.java
@@ -0,0 +1,167 @@
+package se.leap.bitmaskclient.utils;
+/**
+ * Copyright (c) 2019 LEAP Encryption Access Project and contributers
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import android.os.AsyncTask;
+import android.text.TextUtils;
+import android.util.Log;
+
+import java.lang.ref.WeakReference;
+
+import static se.leap.bitmaskclient.utils.Cmd.runBlockingCmd;
+
+interface FirewallCallback {
+    void onFirewallStarted(boolean success);
+    void onFirewallStopped(boolean success);
+}
+
+
+public class FirewallHelper implements FirewallCallback {
+    private static String BITMASK_CHAIN = "bitmask_fw";
+    private static final String TAG = FirewallHelper.class.getSimpleName();
+
+
+    @Override
+    public void onFirewallStarted(boolean success) {
+        Log.d(TAG, "Firewall started " + success);
+    }
+
+    @Override
+    public void onFirewallStopped(boolean success) {
+        Log.d(TAG, "Firewall stopped " + success);
+    }
+
+
+    static class StartFirewallTask extends  AsyncTask<Void, Boolean, Boolean> {
+
+       WeakReference<FirewallCallback> callbackWeakReference;
+
+        public StartFirewallTask(FirewallCallback callback) {
+            callbackWeakReference = new WeakReference<>(callback);
+        }
+
+        @Override
+        protected Boolean doInBackground(Void... voids) {
+            if (requestSU()) {
+                Log.d(TAG, "su acquired");
+                StringBuilder log = new StringBuilder();
+                String[] bitmaskChain = new String[]{
+                        "su",
+                        "ip6tables --list " + BITMASK_CHAIN };
+                try {
+                    boolean hasBitmaskChain = runBlockingCmd(bitmaskChain, log) == 0;
+                    Log.d(TAG, log.toString());
+                    if (!hasBitmaskChain) {
+                        String[] createChain = new String[]{
+                                "su",
+                                "ip6tables --new-chain " + BITMASK_CHAIN,
+                                "ip6tables --insert OUTPUT --jump " + BITMASK_CHAIN };
+                        log = new StringBuilder();
+                        int success = runBlockingCmd(createChain, log);
+                        Log.d(TAG, "added " + BITMASK_CHAIN + " to ip6tables: " + success);
+                        Log.d(TAG, log.toString());
+                        if (success != 0) {
+                            return false;
+                        }
+                    }
+
+                    log = new StringBuilder();
+                    String[] addRules = new String[] {
+                            "su",
+                            "ip6tables --append " + BITMASK_CHAIN + " -p tcp --jump REJECT",
+                            "ip6tables --append " + BITMASK_CHAIN + " -p udp --jump REJECT" };
+                    boolean successResult = runBlockingCmd(addRules, log) == 0;
+                    Log.d(TAG, log.toString());
+                    return successResult;
+                } catch (Exception e) {
+                    e.printStackTrace();
+                    Log.e(TAG, log.toString());
+                }
+            };
+            return false;
+        }
+
+        @Override
+        protected void onPostExecute(Boolean result) {
+            super.onPostExecute(result);
+            FirewallCallback callback = callbackWeakReference.get();
+            if (callback != null) {
+                callback.onFirewallStarted(result);
+            }
+        }
+    }
+
+    static class ShutdownFirewallTask extends AsyncTask<Void, Boolean, Boolean> {
+
+        @Override
+        protected Boolean doInBackground(Void... voids) {
+
+            if (requestSU()) {
+                StringBuilder log = new StringBuilder();
+                String[] deleteChain = new String[]{
+                        "su",
+                        "ip6tables --delete OUTPUT --jump " + BITMASK_CHAIN,
+                        "ip6tables --flush " + BITMASK_CHAIN,
+                        "ip6tables --delete-chain " + BITMASK_CHAIN
+                };
+                try {
+                    runBlockingCmd(deleteChain, log);
+                } catch (Exception e) {
+                    e.printStackTrace();
+                    Log.e(TAG, log.toString());
+                }
+
+            }
+
+            return null;
+        }
+    }
+
+
+    public void startFirewall() {
+        StartFirewallTask task = new StartFirewallTask(this);
+        task.execute();
+    }
+
+    public void shutdownFirewall() {
+        ShutdownFirewallTask task = new ShutdownFirewallTask();
+        task.execute();
+    }
+
+    public static boolean hasSU() {
+        StringBuilder log = new StringBuilder();
+
+        try {
+            String suCommand = "su -v";
+            runBlockingCmd(new String[]{suCommand}, log);
+        } catch (Exception e) {
+            return false;
+        }
+
+        return !TextUtils.isEmpty(log) && !log.toString().contains("su: not found");
+    }
+
+    public static boolean requestSU() {
+        try {
+            String suCommand = "su";
+            return  runBlockingCmd(new String[]{suCommand}, null) == 0;
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+}