tunnel: remove kernel module downloader

Nathan Chance dropped the ball repeatedly and never maintained this in a
consistent way that anybody could use. With Android 12 out now, just
drop it all together. A bummer, but I don't see much of a choice.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

5 files changed, 20 insertions, 116 deletions

diff --git a/ui/src/main/java/com/wireguard/android/Application.kt b/ui/src/main/java/com/wireguard/android/Application.kt
index 13d372c6..60b3d141 100644
--- a/ui/src/main/java/com/wireguard/android/Application.kt
+++ b/ui/src/main/java/com/wireguard/android/Application.kt
@@ -21,7 +21,6 @@ import com.wireguard.android.backend.GoBackend
 import com.wireguard.android.backend.WgQuickBackend
 import com.wireguard.android.configStore.FileConfigStore
 import com.wireguard.android.model.TunnelManager
-import com.wireguard.android.util.ModuleLoader
 import com.wireguard.android.util.RootShell
 import com.wireguard.android.util.ToolsInstaller
 import com.wireguard.android.util.UserKnobs
@@ -42,7 +41,6 @@ class Application : android.app.Application() {
     private val futureBackend = CompletableDeferred<Backend>()
     private val coroutineScope = CoroutineScope(Job() + Dispatchers.Main.immediate)
     private var backend: Backend? = null
-    private lateinit var moduleLoader: ModuleLoader
     private lateinit var rootShell: RootShell
     private lateinit var preferencesDataStore: DataStore<Preferences>
     private lateinit var toolsInstaller: ToolsInstaller
@@ -67,15 +65,7 @@ class Application : android.app.Application() {
     private suspend fun determineBackend(): Backend {
         var backend: Backend? = null
         var didStartRootShell = false
-        if (!ModuleLoader.isModuleLoaded() && moduleLoader.moduleMightExist()) {
-            try {
-                rootShell.start()
-                didStartRootShell = true
-                moduleLoader.loadModule()
-            } catch (ignored: Exception) {
-            }
-        }
-        if (!UserKnobs.disableKernelModule.first() && ModuleLoader.isModuleLoaded()) {
+        if (UserKnobs.enableKernelModule.first() && WgQuickBackend.hasKernelSupport()) {
             try {
                 if (!didStartRootShell)
                     rootShell.start()
@@ -100,7 +90,6 @@ class Application : android.app.Application() {
         super.onCreate()
         rootShell = RootShell(applicationContext)
         toolsInstaller = ToolsInstaller(applicationContext, rootShell)
-        moduleLoader = ModuleLoader(applicationContext, rootShell, USER_AGENT)
         preferencesDataStore = PreferenceDataStoreFactory.create { applicationContext.preferencesDataStoreFile("settings") }
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
             coroutineScope.launch {
@@ -141,9 +130,6 @@ class Application : android.app.Application() {
         suspend fun getBackend() = get().futureBackend.await()
 
         @JvmStatic
-        fun getModuleLoader() = get().moduleLoader
-
-        @JvmStatic
         fun getRootShell() = get().rootShell
 
         @JvmStatic
diff --git a/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt b/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt
index 06091cae..4196797c 100644
--- a/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt
+++ b/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt
@@ -17,7 +17,6 @@ import com.wireguard.android.R
 import com.wireguard.android.backend.WgQuickBackend
 import com.wireguard.android.preference.PreferencesPreferenceDataStore
 import com.wireguard.android.util.AdminKnobs
-import com.wireguard.android.util.ModuleLoader
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -79,30 +78,19 @@ class SettingsActivity : ThemeChangeAwareActivity() {
                 startActivity(Intent(requireContext(), LogViewerActivity::class.java))
                 true
             }
-            val moduleInstaller = preferenceManager.findPreference<Preference>("module_downloader")
-            val kernelModuleDisabler = preferenceManager.findPreference<Preference>("kernel_module_disabler")
-            moduleInstaller?.isVisible = false
-            if (ModuleLoader.isModuleLoaded()) {
-                moduleInstaller?.parent?.removePreference(moduleInstaller)
+            val kernelModuleEnabler = preferenceManager.findPreference<Preference>("kernel_module_enabler")
+            if (WgQuickBackend.hasKernelSupport()) {
                 lifecycleScope.launch {
                     if (Application.getBackend() !is WgQuickBackend) {
                         try {
                             withContext(Dispatchers.IO) { Application.getRootShell().start() }
                         } catch (_: Throwable) {
-                            kernelModuleDisabler?.parent?.removePreference(kernelModuleDisabler)
+                            kernelModuleEnabler?.parent?.removePreference(kernelModuleEnabler)
                         }
                     }
                 }
             } else {
-                kernelModuleDisabler?.parent?.removePreference(kernelModuleDisabler)
-                lifecycleScope.launch {
-                    try {
-                        withContext(Dispatchers.IO) { Application.getRootShell().start() }
-                        moduleInstaller?.isVisible = true
-                    } catch (_: Throwable) {
-                        moduleInstaller?.parent?.removePreference(moduleInstaller)
-                    }
-                }
+                kernelModuleEnabler?.parent?.removePreference(kernelModuleEnabler)
             }
         }
     }
diff --git a/ui/src/main/java/com/wireguard/android/preference/KernelModuleDisablerPreference.kt b/ui/src/main/java/com/wireguard/android/preference/KernelModuleEnablerPreference.kt
index 2b1e8e4e..46f699a5 100644
--- a/ui/src/main/java/com/wireguard/android/preference/KernelModuleDisablerPreference.kt
+++ b/ui/src/main/java/com/wireguard/android/preference/KernelModuleEnablerPreference.kt
@@ -26,7 +26,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import kotlin.system.exitProcess
 
-class KernelModuleDisablerPreference(context: Context, attrs: AttributeSet?) : Preference(context, attrs) {
+class KernelModuleEnablerPreference(context: Context, attrs: AttributeSet?) : Preference(context, attrs) {
     private var state = State.UNKNOWN
 
     init {
@@ -44,10 +44,10 @@ class KernelModuleDisablerPreference(context: Context, attrs: AttributeSet?) : P
         activity.lifecycleScope.launch {
             if (state == State.DISABLED) {
                 setState(State.ENABLING)
-                UserKnobs.setDisableKernelModule(false)
+                UserKnobs.setEnableKernelModule(true)
             } else if (state == State.ENABLED) {
                 setState(State.DISABLING)
-                UserKnobs.setDisableKernelModule(true)
+                UserKnobs.setEnableKernelModule(false)
             }
             val observableTunnels = Application.getTunnelManager().getTunnels()
             val downings = observableTunnels.map { async(SupervisorJob()) { it.setStateAsync(Tunnel.State.DOWN) } }
@@ -76,13 +76,13 @@ class KernelModuleDisablerPreference(context: Context, attrs: AttributeSet?) : P
 
     private enum class State(val titleResourceId: Int, val summaryResourceId: Int, val shouldEnableView: Boolean, val visible: Boolean) {
         UNKNOWN(0, 0, false, false),
-        ENABLED(R.string.module_disabler_enabled_title, R.string.module_disabler_enabled_summary, true, true),
-        DISABLED(R.string.module_disabler_disabled_title, R.string.module_disabler_disabled_summary, true, true),
-        ENABLING(R.string.module_disabler_disabled_title, R.string.success_application_will_restart, false, true),
-        DISABLING(R.string.module_disabler_enabled_title, R.string.success_application_will_restart, false, true);
+        ENABLED(R.string.module_enabler_enabled_title, R.string.module_enabler_enabled_summary, true, true),
+        DISABLED(R.string.module_enabler_disabled_title, R.string.module_enabler_disabled_summary, true, true),
+        ENABLING(R.string.module_enabler_disabled_title, R.string.success_application_will_restart, false, true),
+        DISABLING(R.string.module_enabler_enabled_title, R.string.success_application_will_restart, false, true);
     }
 
     companion object {
-        private const val TAG = "WireGuard/KernelModuleDisablerPreference"
+        private const val TAG = "WireGuard/KernelModuleEnablerPreference"
     }
 }
diff --git a/ui/src/main/java/com/wireguard/android/preference/ModuleDownloaderPreference.kt b/ui/src/main/java/com/wireguard/android/preference/ModuleDownloaderPreference.kt
deleted file mode 100644
index 5ba2c4f0..00000000
--- a/ui/src/main/java/com/wireguard/android/preference/ModuleDownloaderPreference.kt
+++ /dev/null
@@ -1,70 +0,0 @@
-/*
- * Copyright © 2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-package com.wireguard.android.preference
-
-import android.content.Context
-import android.content.Intent
-import android.system.OsConstants
-import android.util.AttributeSet
-import android.widget.Toast
-import androidx.preference.Preference
-import com.wireguard.android.Application
-import com.wireguard.android.R
-import com.wireguard.android.activity.SettingsActivity
-import com.wireguard.android.util.ErrorMessages
-import com.wireguard.android.util.UserKnobs
-import com.wireguard.android.util.lifecycleScope
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.launch
-import kotlinx.coroutines.withContext
-import kotlin.system.exitProcess
-
-class ModuleDownloaderPreference(context: Context, attrs: AttributeSet?) : Preference(context, attrs) {
-    private var state = State.INITIAL
-    override fun getSummary() = context.getString(state.messageResourceId)
-
-    override fun getTitle() = context.getString(R.string.module_installer_title)
-
-    override fun onClick() {
-        setState(State.WORKING)
-        lifecycleScope.launch {
-            try {
-                when (withContext(Dispatchers.IO) { Application.getModuleLoader().download() }) {
-                    OsConstants.ENOENT -> setState(State.NOTFOUND)
-                    OsConstants.EXIT_SUCCESS -> {
-                        setState(State.SUCCESS)
-                        UserKnobs.setDisableKernelModule(null)
-                        withContext(Dispatchers.IO) {
-                            val restartIntent = Intent(context, SettingsActivity::class.java)
-                            restartIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
-                            restartIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
-                            Application.get().startActivity(restartIntent)
-                            exitProcess(0)
-                        }
-                    }
-                    else -> setState(State.FAILURE)
-                }
-            } catch (e: Throwable) {
-                setState(State.FAILURE)
-                Toast.makeText(context, ErrorMessages[e], Toast.LENGTH_LONG).show()
-            }
-        }
-    }
-
-    private fun setState(state: State) {
-        if (this.state == state) return
-        this.state = state
-        if (isEnabled != state.shouldEnableView) isEnabled = state.shouldEnableView
-        notifyChanged()
-    }
-
-    private enum class State(val messageResourceId: Int, val shouldEnableView: Boolean) {
-        INITIAL(R.string.module_installer_initial, true),
-        FAILURE(R.string.module_installer_error, true),
-        WORKING(R.string.module_installer_working, false),
-        SUCCESS(R.string.success_application_will_restart, false),
-        NOTFOUND(R.string.module_installer_not_found, false);
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/util/UserKnobs.kt b/ui/src/main/java/com/wireguard/android/util/UserKnobs.kt
index a983bf5a..50e473ce 100644
--- a/ui/src/main/java/com/wireguard/android/util/UserKnobs.kt
+++ b/ui/src/main/java/com/wireguard/android/util/UserKnobs.kt
@@ -14,18 +14,18 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 
 object UserKnobs {
-    private val DISABLE_KERNEL_MODULE = booleanPreferencesKey("disable_kernel_module")
-    val disableKernelModule: Flow<Boolean>
+    private val ENABLE_KERNEL_MODULE = booleanPreferencesKey("enable_kernel_module")
+    val enableKernelModule: Flow<Boolean>
         get() = Application.getPreferencesDataStore().data.map {
-            it[DISABLE_KERNEL_MODULE] ?: false
+            it[ENABLE_KERNEL_MODULE] ?: false
         }
 
-    suspend fun setDisableKernelModule(disable: Boolean?) {
+    suspend fun setEnableKernelModule(enable: Boolean?) {
         Application.getPreferencesDataStore().edit {
-            if (disable == null)
-                it.remove(DISABLE_KERNEL_MODULE)
+            if (enable == null)
+                it.remove(ENABLE_KERNEL_MODULE)
             else
-                it[DISABLE_KERNEL_MODULE] = disable
+                it[ENABLE_KERNEL_MODULE] = enable
         }
     }