manager | ksud: Add toggle for global mount namespace (#99)

* This is untested, if you facing any issues, open a new issue or comments at our group
* and also, this changes maybe reverted if didn't meet the target.

Taken from Apatch's implementations:
8de6b9d676
57d527a846
f093d6a633

Critics are welcome!

Signed-off-by: rsuntk <90097027+rsuntk@users.noreply.github.com>

manager/app/src/main/java/com/rifsxd/ksunext/Natives.kt

@@ -120,6 +120,9 @@ object Natives {
         return version < MINIMAL_SUPPORTED_KERNEL
     }
 
+    val KSU_WORK_DIR = "/data/adb/ksu/"
+    val GLOBAL_NAMESPACE_FILE = KSU_WORK_DIR + ".global_mnt"
+
     @Immutable
     @Parcelize
     @Keep

manager/app/src/main/java/com/rifsxd/ksunext/ui/screen/Settings.kt

@@ -88,6 +88,8 @@ import com.rifsxd.ksunext.ui.component.rememberLoadingDialog
 import com.rifsxd.ksunext.ui.util.LocalSnackbarHost
 import com.rifsxd.ksunext.ui.util.getBugreportFile
 import com.rifsxd.ksunext.ui.util.*
+import com.rifsxd.ksunext.ui.util.isGlobalNamespaceEnabled
+import com.rifsxd.ksunext.ui.util.setGlobalNamespaceEnabled
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
 
@@ -101,6 +103,8 @@ import java.time.format.DateTimeFormatter
 fun SettingScreen(navigator: DestinationsNavigator) {
     val scrollBehavior = TopAppBarDefaults.pinnedScrollBehavior(rememberTopAppBarState())
     val snackBarHost = LocalSnackbarHost.current
+    var isGlobalNamespaceEnabled by rememberSaveable { mutableStateOf(false) }
+    isGlobalNamespaceEnabled = isGlobalNamespaceEnabled()
 
     val isManager = Natives.becomeManager(ksuApp.packageName)
     val ksuVersion = if (isManager) Natives.version else null
@@ -196,6 +200,23 @@ fun SettingScreen(navigator: DestinationsNavigator) {
                         }
                     }
                 }
+                
+                SwitchItem(
+                    icon = Icons.Filled.Engineering,
+                    title = stringResource(id = R.string.settings_global_namespace_mode),
+                    summary = stringResource(id = R.string.settings_global_namespace_mode_summary),
+                    checked = isGlobalNamespaceEnabled,
+                    onCheckedChange = {
+                        setGlobalNamespaceEnabled(
+                            if (isGlobalNamespaceEnabled) {
+                                "0"
+                            } else {
+                                "1"
+                            }
+                        )
+                        isGlobalNamespaceEnabled = it
+                    }
+                )
             }
 
             val prefs = context.getSharedPreferences("settings", Context.MODE_PRIVATE)

manager/app/src/main/java/com/rifsxd/ksunext/ui/util/KsuCli.kt

@@ -103,7 +103,10 @@ fun Uri.getFileName(context: Context): String? {
 
 fun createRootShell(globalMnt: Boolean = false): Shell {
     Shell.enableVerboseLogging = BuildConfig.DEBUG
-    val builder = Shell.Builder.create()
+    val builder = Shell.Builder.create().apply {
+        setFlags(Shell.FLAG_MOUNT_MASTER)
+    }
+
     return try {
         if (globalMnt) {
             builder.build(ksuDaemonMagicPath(), "debug", "su", "-g")
@@ -403,6 +406,22 @@ fun hasMagisk(): Boolean {
     return result.isSuccess
 }
 
+fun isGlobalNamespaceEnabled(): Boolean {
+    val shell = getRootShell()
+    val result =
+        ShellUtils.fastCmd(shell, "nsenter --mount=/proc/1/ns/mnt cat ${Natives.GLOBAL_NAMESPACE_FILE}")
+    Log.i(TAG, "is global namespace enabled: $result")
+    return result == "1"
+}
+
+fun setGlobalNamespaceEnabled(value: String) {
+    getRootShell().newJob()
+        .add("nsenter --mount=/proc/1/ns/mnt echo $value > ${Natives.GLOBAL_NAMESPACE_FILE}")
+        .submit { result ->
+            Log.i(TAG, "setGlobalNamespaceEnabled result: ${result.isSuccess} [${result.out}]")
+        }
+}
+
 fun isSepolicyValid(rules: String?): Boolean {
     if (rules == null) {
         return true

manager/app/src/main/res/values/strings.xml

@@ -231,4 +231,6 @@
     <string name="module_sort_enabled_first">Sort (Enabled first)</string>
     <string name="module_sort_action_first">Sort (Action first)</string>
     <string name="module_sort_webui_first">Sort (WebUI first)</string>
+    <string name="settings_global_namespace_mode">Global Namespace Mode</string>
+    <string name="settings_global_namespace_mode_summary">All root sessions use the global mount namespace</string>
 </resources>

userspace/ksud_magic/src/defs.rs

@@ -44,3 +44,5 @@ pub const NO_TMPFS_PATH: &str = concatcp!(WORKING_DIR, ".notmpfs");
 pub const NO_MOUNT_PATH: &str = concatcp!(WORKING_DIR, ".nomount");
 
 pub const MOUNT_SYSTEM: &str = "Magic_Mount";
+
+pub const GLOBAL_NAMESPACE_FILE: &str = concatcp!(WORKING_DIR, ".global_mnt");

userspace/ksud_magic/src/su.rs

@@ -261,7 +261,10 @@ pub fn root_shell() -> Result<()> {
 
             // switch to global mount namespace
             #[cfg(any(target_os = "linux", target_os = "android"))]
-            if mount_master {
+            let global_namespace_enable =
+                std::fs::read_to_string(defs::GLOBAL_NAMESPACE_FILE)
+                    .unwrap_or("0".to_string());
+            if global_namespace_enable.trim() == "1" || mount_master {
                 let _ = utils::switch_mnt_ns(1);
             }
 

userspace/ksud_overlayfs/src/defs.rs

@@ -47,3 +47,5 @@ pub const KSU_BACKUP_FILE_PREFIX: &str = "ksu_backup_";
 pub const BACKUP_FILENAME: &str = "stock_image.sha1";
 
 pub const MOUNT_SYSTEM: &str = "OverlayFS";
+
+pub const GLOBAL_NAMESPACE_FILE: &str = concatcp!(WORKING_DIR, ".global_mnt");

userspace/ksud_overlayfs/src/su.rs

@@ -261,7 +261,10 @@ pub fn root_shell() -> Result<()> {
 
             // switch to global mount namespace
             #[cfg(any(target_os = "linux", target_os = "android"))]
-            if mount_master {
+            let global_namespace_enable =
+                std::fs::read_to_string(defs::GLOBAL_NAMESPACE_FILE)
+                    .unwrap_or("0".to_string());
+            if global_namespace_enable.trim() == "1" || mount_master {
                 let _ = utils::switch_mnt_ns(1);
             }