Revert "Use rootfs for magisktmp if possible"

vvb2060 · web-flow · commit 9a776c22d91e · 2025-12-01T11:45:34.000-08:00
diff --git a/native/src/core/mount.rs b/native/src/core/mount.rs
@@ -221,10 +221,7 @@ pub fn revert_unmount(pid: i32) {
 
     // Unmount Magisk tmpfs and mounts from module files
     for info in parse_mount_info("self") {
-        if info.source == "magisk"
-            || info.root.starts_with("/adb/modules")
-            || (info.fs_type == "rootfs" && info.root.starts_with("/magisk"))
-        {
+        if info.source == "magisk" || info.root.starts_with("/adb/modules") {
             targets.push(info.target);
         }
     }
diff --git a/native/src/init/init.rs b/native/src/init/init.rs
@@ -1,10 +1,9 @@
 use crate::ffi::{BootConfig, MagiskInit, backup_init, magisk_proxy_main};
 use crate::logging::setup_klog;
-use crate::mount::{is_rootfs, occupy, unoccupy};
+use crate::mount::is_rootfs;
 use crate::twostage::hexpatch_init_for_second_stage;
 use base::libc::{basename, getpid, mount, umask};
-use base::nix::mount::MsFlags;
-use base::{LibcReturn, LoggedResult, ResultExt, Utf8CStr, cstr, info, nix, raw_cstr};
+use base::{LibcReturn, LoggedResult, ResultExt, cstr, info, raw_cstr};
 use std::ffi::{CStr, c_char};
 use std::ptr::null;
 
@@ -32,7 +31,7 @@ impl MagiskInit {
 
     fn first_stage(&self) {
         info!("First Stage Init");
-        let rootfs_magisktmp = self.prepare_data(true);
+        self.prepare_data();
 
         if !cstr!("/sdcard").exists() && !cstr!("/first_stage_ramdisk/sdcard").exists() {
             self.hijack_init_with_switch_root();
@@ -42,28 +41,11 @@ impl MagiskInit {
             // Fallback to hexpatch if /sdcard exists
             hexpatch_init_for_second_stage(true);
         }
-
-        if rootfs_magisktmp {
-            info!("Occupy /data");
-            occupy(cstr!("/data"));
-        }
     }
 
     fn second_stage(&mut self) {
         info!("Second Stage Init");
 
-        if unoccupy(cstr!("/data")) {
-            nix::mount::mount(
-                None::<&Utf8CStr>,
-                cstr!("/data"),
-                None::<&Utf8CStr>,
-                MsFlags::MS_REMOUNT,
-                Some(cstr!("size=100%")),
-            )
-            .check_os_err("mount", Some("/data"), Some("tmpfs"))
-            .log_ok();
-        }
-
         cstr!("/init").unmount().ok();
         cstr!("/system/bin/init").unmount().ok(); // just in case
         cstr!("/data/init").remove().ok();
@@ -89,7 +71,7 @@ impl MagiskInit {
 
     fn legacy_system_as_root(&mut self) {
         info!("Legacy SAR Init");
-        self.prepare_data(false);
+        self.prepare_data();
         let is_two_stage = self.mount_system_root();
         if is_two_stage {
             hexpatch_init_for_second_stage(false);
@@ -100,7 +82,7 @@ impl MagiskInit {
 
     fn rootfs(&mut self) {
         info!("RootFS Init");
-        self.prepare_data(false);
+        self.prepare_data();
         self.restore_ramdisk_init();
         self.patch_rw_root();
     }
diff --git a/native/src/init/mount.rs b/native/src/init/mount.rs
@@ -1,6 +1,4 @@
 use crate::ffi::MagiskInit;
-use base::WalkResult::{Continue, Skip};
-use base::nix::mount::{MntFlags, mount, umount2};
 use base::{
     Directory, FsPathBuilder, LibcReturn, LoggedResult, ResultExt, Utf8CStr, cstr, debug, libc,
     nix, parse_mount_info, raw_cstr,
@@ -64,54 +62,6 @@ pub(crate) fn is_device_mounted(dev: u64, target: Pin<&mut CxxString>) -> bool {
     false
 }
 
-pub(crate) fn occupy(path: &Utf8CStr) {
-    Directory::open(path)
-        .map(|mut dir| {
-            dir.pre_order_walk(|entry| {
-                let mut path = cstr::buf::default();
-                entry.resolve_path(&mut path)?;
-                let path = path.as_utf8_cstr();
-                mount(
-                    Some(path),
-                    path,
-                    None::<&Utf8CStr>,
-                    MsFlags::MS_BIND | MsFlags::MS_RDONLY,
-                    None::<&Utf8CStr>,
-                )
-                .check_os_err("occupy", Some(path), None)?;
-                Ok(Continue)
-            })
-            .log_ok();
-        })
-        .log_ok();
-}
-
-pub(crate) fn unoccupy(path: &Utf8CStr) -> bool {
-    let mut ok = false;
-    Directory::open(path)
-        .map(|mut dir| {
-            ok = dir
-                .pre_order_walk(|entry| {
-                    let mut path = cstr::buf::default();
-                    entry.resolve_path(&mut path)?;
-                    let path = path.as_utf8_cstr();
-                    umount2(path, MntFlags::MNT_DETACH).check_os_err(
-                        "unoccupy",
-                        Some(path),
-                        None,
-                    )?;
-                    if entry.is_dir() {
-                        Ok(Skip)
-                    } else {
-                        Ok(Continue)
-                    }
-                })
-                .is_ok();
-        })
-        .log_ok();
-    ok
-}
-
 const RAMFS_MAGIC: u32 = 0x858458f6;
 
 pub(crate) fn is_rootfs() -> bool {
@@ -123,44 +73,22 @@ pub(crate) fn is_rootfs() -> bool {
 }
 
 impl MagiskInit {
-    pub(crate) fn prepare_data(&self, use_rootfs: bool) -> bool {
+    pub(crate) fn prepare_data(&self) {
         debug!("Setup data tmp");
         cstr!("/data").mkdir(0o755).log_ok();
+        nix::mount::mount(
+            Some(cstr!("magisk")),
+            cstr!("/data"),
+            Some(cstr!("tmpfs")),
+            MsFlags::empty(),
+            Some(cstr!("mode=755")),
+        )
+        .check_os_err("mount", Some("/data"), Some("tmpfs"))
+        .log_ok();
 
-        let mut rootfs_magisktmp = false;
-
-        if use_rootfs {
-            cstr!("/magisk").mkdir(0o755).log_ok();
-            rootfs_magisktmp = cstr!("/magisk")
-                .bind_mount_to(cstr!("/data"), false)
-                .is_ok();
-        }
-
-        if rootfs_magisktmp {
-            cstr!("/init")
-                .rename_to(cstr!("/magisk/magiskinit"))
-                .log_ok();
-            cstr!("/.backup").copy_to(cstr!("/magisk/.backup")).ok();
-            cstr!("/overlay.d")
-                .rename_to(cstr!("/magisk/overlay.d"))
-                .ok();
-        } else {
-            nix::mount::mount(
-                Some(cstr!("magisk")),
-                cstr!("/data"),
-                Some(cstr!("tmpfs")),
-                MsFlags::empty(),
-                Some(cstr!("mode=755")),
-            )
-            .check_os_err("mount", Some("/data"), Some("tmpfs"))
-            .log_ok();
-
-            cstr!("/init").copy_to(cstr!("/data/magiskinit")).ok();
-            cstr!("/.backup").copy_to(cstr!("/data/.backup")).ok();
-            cstr!("/overlay.d").copy_to(cstr!("/data/overlay.d")).ok();
-        }
-
-        rootfs_magisktmp
+        cstr!("/init").copy_to(cstr!("/data/magiskinit")).ok();
+        cstr!("/.backup").copy_to(cstr!("/data/.backup")).ok();
+        cstr!("/overlay.d").copy_to(cstr!("/data/overlay.d")).ok();
     }
 
     pub(crate) fn exec_init(&mut self) {
diff --git a/native/src/init/twostage.rs b/native/src/init/twostage.rs
@@ -84,14 +84,20 @@ impl MagiskInit {
                 .log_ok();
             debug!("Symlink /storage/self/primary -> /system/system/bin/init");
         }
+        cstr!("/init").rename_to(cstr!("/sdcard")).log_ok();
 
-        // Binding mounting from rootfs is not supported before Linux 3.12
-        cstr!("/sdcard")
-            .create(OFlag::O_RDONLY | OFlag::O_CLOEXEC, 0)
-            .log_ok();
-        cstr!("/data/magiskinit")
+        // First try to mount magiskinit from rootfs to workaround Samsung RKP
+        if cstr!("/sdcard")
             .bind_mount_to(cstr!("/sdcard"), false)
-            .log_ok();
-        debug!("Bind mount /data/magiskinit -> /sdcard");
+            .is_ok()
+        {
+            debug!("Bind mount /sdcard -> /sdcard");
+        } else {
+            // Binding mounting from rootfs is not supported before Linux 3.12
+            cstr!("/data/magiskinit")
+                .bind_mount_to(cstr!("/sdcard"), false)
+                .log_ok();
+            debug!("Bind mount /data/magiskinit -> /sdcard");
+        }
     }
 }
diff --git a/native/src/sepolicy/rules.rs b/native/src/sepolicy/rules.rs
@@ -110,7 +110,7 @@ impl SePolicy {
             allow(["kernel"], ["rootfs", "tmpfs"], ["chr_file"], ["write"]);
 
             // Allow magiskinit daemon to handle mock selinuxfs
-            allow(["kernel"], ["rootfs", "tmpfs"], ["fifo_file"], ["open", "read", "write"]);
+            allow(["kernel"], ["tmpfs"], ["fifo_file"], ["open", "read", "write"]);
 
             // For relabelling files
             allow(["rootfs"], ["labeledfs", "tmpfs"], ["filesystem"], ["associate"]);

Original file line number	Diff line number	Diff line change
`@@ -221,10 +221,7 @@ pub fn revert_unmount(pid: i32) {`
`221`	`221`
`222`	`222`	`// Unmount Magisk tmpfs and mounts from module files`
`223`	`223`	`for info in parse_mount_info("self") {`
`224`		`- if info.source == "magisk"`
`225`		`- \|\| info.root.starts_with("/adb/modules")`
`226`		`- \|\| (info.fs_type == "rootfs" && info.root.starts_with("/magisk"))`
`227`		`- {`
	`224`	`+ if info.source == "magisk" \|\| info.root.starts_with("/adb/modules") {`
`228`	`225`	`targets.push(info.target);`
`229`	`226`	`}`
`230`	`227`	`}`