implement wifi tethering

1 files changed, 187 insertions, 0 deletions

diff --git a/app/src/main/java/se/leap/bitmaskclient/firewall/SetupTetheringTask.java b/app/src/main/java/se/leap/bitmaskclient/firewall/SetupTetheringTask.java
new file mode 100644
index 00000000..93054099
--- /dev/null
+++ b/app/src/main/java/se/leap/bitmaskclient/firewall/SetupTetheringTask.java
@@ -0,0 +1,187 @@
+/**
+ * Copyright (c) 2020 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.firewall;
+
+import android.os.AsyncTask;
+import android.util.Log;
+
+import java.lang.ref.WeakReference;
+import java.net.NetworkInterface;
+import java.util.Enumeration;
+
+import se.leap.bitmaskclient.tethering.TetheringObservable;
+import se.leap.bitmaskclient.tethering.TetheringState;
+
+import static se.leap.bitmaskclient.firewall.FirewallManager.BITMASK_FORWARD;
+import static se.leap.bitmaskclient.firewall.FirewallManager.BITMASK_POSTROUTING;
+import static se.leap.bitmaskclient.utils.Cmd.runBlockingCmd;
+
+public class SetupTetheringTask extends AsyncTask<Void, Boolean, Boolean> {
+
+    private static final String TAG = SetupTetheringTask.class.getSimpleName();
+    private WeakReference<FirewallCallback> callbackWeakReference;
+
+    SetupTetheringTask(FirewallCallback callback) {
+        callbackWeakReference = new WeakReference<>(callback);
+    }
+
+    @Override
+    protected Boolean doInBackground(Void... args) {
+        TetheringState tetheringState = TetheringObservable.getInstance().getTetheringState();
+        StringBuilder log = new StringBuilder();
+
+        String[] bitmaskChain = new String[]{
+                "su",
+                "id",
+                "iptables -t filter --list " + BITMASK_FORWARD + " && iptables -t nat --list " + BITMASK_POSTROUTING };
+
+        try {
+            boolean hasBitmaskChain = runBlockingCmd(bitmaskChain, log) == 0;
+            boolean allowSu = log.toString().contains("uid=0");
+            callbackWeakReference.get().onSuRequested(allowSu);
+            if (!allowSu) {
+                return false;
+            }
+
+            boolean success = true;
+            log = new StringBuilder();
+
+            if (!hasBitmaskChain && tetheringState.hasAnyVpnTetheringAllowed() && tetheringState.hasAnyDeviceTetheringEnabled()) {
+                createChains(log);
+            }
+
+            if (tetheringState.tetherWifiVpn()) {
+                log = new StringBuilder();
+                success = addWifiTetheringRules(tetheringState, log);
+            } else if (!tetheringState.isVpnWifiTetheringAllowed){
+                success = removeWifiTetheringRules(tetheringState, log);
+            }
+
+            if (tetheringState.tetherUsbVpn()) {
+                success = success && addUsbTetheringRules(tetheringState, log);
+            } else if (!tetheringState.isVpnUsbTetheringAllowed) {
+                success = success && removeUsbTetheringRules(tetheringState, log);
+            }
+
+            if (tetheringState.tetherBluetoothVpn()) {
+                success = success && addBluetoothTetheringRules(tetheringState, log);
+            } else if (!tetheringState.isVpnBluetoothTetheringAllowed) {
+                success = success && removeBluetoothTetheringRules(tetheringState, log);
+            }
+            return success;
+        } catch (Exception e) {
+            e.printStackTrace();
+            Log.e(FirewallManager.TAG, log.toString());
+        }
+        return false;
+    }
+
+
+    //TODO: implement the follwing methods -v
+    private boolean removeBluetoothTetheringRules(TetheringState tetheringState, StringBuilder log) {
+        return true;
+    }
+
+    private boolean removeUsbTetheringRules(TetheringState tetheringState, StringBuilder log) {
+        return true;
+    }
+
+    private boolean addBluetoothTetheringRules(TetheringState tetheringState, StringBuilder log) {
+        return true;
+    }
+
+    private boolean addUsbTetheringRules(TetheringState tetheringState, StringBuilder log) {
+        return true;
+    }
+
+
+    private void createChains(StringBuilder log) throws Exception {
+        boolean success;
+        String[] createChains = new String[]{
+                "su",
+                "iptables -t filter --new-chain " + BITMASK_FORWARD,
+                "iptables -t nat --new-chain " + BITMASK_POSTROUTING,
+                "iptables -t filter --insert FORWARD --jump " + BITMASK_FORWARD,
+                "iptables -t nat --insert POSTROUTING --jump " + BITMASK_POSTROUTING,
+        };
+        success = runBlockingCmd(createChains, log) == 0;
+        Log.d(FirewallManager.TAG, "added " + BITMASK_FORWARD + " and " + BITMASK_POSTROUTING+" to iptables: " + success);
+        Log.d(FirewallManager.TAG, log.toString());
+    }
+
+    private boolean addWifiTetheringRules(TetheringState state, StringBuilder log) throws Exception {
+        Log.d(TAG, "add Wifi tethering Rules");
+        String[] addRules = new String[] {
+                "su",
+                "iptables -t filter --flush " + BITMASK_FORWARD,
+                "iptables -t nat --flush " + BITMASK_POSTROUTING,
+                "iptables -t filter --append " + BITMASK_FORWARD + " --jump ACCEPT",
+                "iptables -t nat --append " + BITMASK_POSTROUTING + " --jump MASQUERADE",
+                "if [[ ! `ip rule show from "+ state.wifiAddress+" lookup 61` ]]; " +
+                        "then ip rule add from " + state.wifiAddress + " lookup 61; " +
+                        "fi",
+                "if [[ ! `ip route list table 61 | grep 'default dev " + getTunName() + " scope link'` ]]; " +
+                        "then ip route add default dev " + getTunName() + " scope link table 61; " +
+                        "fi",
+                "if [[ ! `ip route list table 61 | grep '"+ state.wifiAddress+" dev "+ state.wifiInterface+" scope link'` ]]; " +
+                        "then ip route add " + state.wifiAddress + " dev " + state.wifiInterface + " scope link table 61; " +
+                        "fi",
+                "if [[ ! `ip route list table 61 | grep 'broadcast 255.255.255.255 dev " + state.wifiInterface + " scope link'` ]]; " +
+                        "then ip route add broadcast 255.255.255.255 dev " + state.wifiInterface + " scope link table 61; " +
+                        "fi"
+        };
+
+        return runBlockingCmd(addRules, log) == 0;
+    }
+
+    private boolean removeWifiTetheringRules(TetheringState state, StringBuilder log) throws Exception {
+        Log.d(TAG, "add Wifi tethering Rules");
+        String[] removeRules = new String[] {
+                "su",
+                "ip route delete broadcast 255.255.255.255 dev " + state.wifiInterface +" scope link table 61",
+                "ip route delete " + state.lastWifiAddress + " dev " + state.wifiInterface +" scope link table 61",
+                "ip route delete default dev " + getTunName() + " scope link table 61",
+                "if [[ `ip rule show from " + state.wifiAddress+ " lookup 61` ]]; " +
+                        "then ip rule del from " + state.wifiAddress + " lookup 61; " +
+                        "fi",
+        };
+        return runBlockingCmd(removeRules, log) == 0;
+    }
+
+    private String getTunName() {
+        try {
+            for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements(); ) {
+                NetworkInterface networkInterface = en.nextElement();
+                if (networkInterface.getName().contains("tun")) {
+                    return networkInterface.getName();
+                }
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return "";
+    }
+
+    @Override
+    protected void onPostExecute(Boolean result) {
+        super.onPostExecute(result);
+        FirewallCallback callback = callbackWeakReference.get();
+        if (callback != null) {
+            callback.onTetheringStarted(result);
+        }
+    }
+}