From 736729f5ef646549c8d098b3a8fabf1953d461c8 Mon Sep 17 00:00:00 2001
From: topjohnwu <topjohnwu@gmail.com>
Date: Tue, 16 Jul 2019 23:54:52 -0700
Subject: [PATCH] Maintain a list of pre-init mounts

Keep track of everything to unmount
---
 native/jni/core/daemon.cpp  | 10 ++++++----
 native/jni/include/magisk.h |  2 ++
 native/jni/init/rootdir.cpp |  8 +++++++-
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/native/jni/core/daemon.cpp b/native/jni/core/daemon.cpp
index 0c1243eac..0a72d82ef 100644
--- a/native/jni/core/daemon.cpp
+++ b/native/jni/core/daemon.cpp
@@ -109,10 +109,12 @@ static void main_daemon() {
 	restore_rootcon();
 
 	// Unmount pre-init patches
-	umount2("/init", MNT_DETACH);
-	umount2("/init.rc", MNT_DETACH);
-	umount2("/system/lib/libselinux.so", MNT_DETACH);
-	umount2("/system/lib64/libselinux.so", MNT_DETACH);
+	if (access(ROOTMNT, F_OK) == 0) {
+		file_readline(ROOTMNT, [](auto line) -> bool {
+			umount2(line.data(), MNT_DETACH);
+			return true;
+		}, true);
+	}
 
 	int fd = xopen("/dev/null", O_RDWR | O_CLOEXEC);
 	xdup2(fd, STDOUT_FILENO);
diff --git a/native/jni/include/magisk.h b/native/jni/include/magisk.h
index 4ea5557ce..a6509ede6 100644
--- a/native/jni/include/magisk.h
+++ b/native/jni/include/magisk.h
@@ -12,6 +12,8 @@
 #define BLOCKDIR        MAGISKTMP "/block"
 #define BBPATH          MAGISKTMP "/busybox"
 #define MODULEMNT       MAGISKTMP "/modules"
+#define ROOTOVL         MAGISKTMP "/rootdir"
+#define ROOTMNT         ROOTOVL "/.mount_list"
 #define SECURE_DIR      "/data/adb"
 #define MODULEROOT      SECURE_DIR "/modules"
 #define MODULEUPGRADE   SECURE_DIR "/modules_update"
diff --git a/native/jni/init/rootdir.cpp b/native/jni/init/rootdir.cpp
index 288f396cc..001bfe077 100644
--- a/native/jni/init/rootdir.cpp
+++ b/native/jni/init/rootdir.cpp
@@ -225,13 +225,14 @@ static void sbin_overlay(const raw_data &self, const raw_data &config) {
 	xsymlink("./magiskinit", "/sbin/supolicy");
 }
 
-#define ROOTOVL MAGISKTMP "/rootdir"
 #define ROOTMIR MIRRDIR "/system_root"
 #define ROOTBLK BLOCKDIR "/system_root"
 #define MONOPOLICY  "/sepolicy"
 #define PATCHPOLICY "/sbin/.se"
 #define LIBSELINUX  "/system/" LIBNAME "/libselinux.so"
 
+static string mount_list;
+
 static void magic_mount(int dirfd, const string &path) {
 	DIR *dir = xfdopendir(dirfd);
 	for (dirent *entry; (entry = readdir(dir));) {
@@ -248,6 +249,8 @@ static void magic_mount(int dirfd, const string &path) {
 				string src = ROOTOVL + dest;
 				LOGD("Mount [%s] -> [%s]\n", src.data(), dest.data());
 				xmount(src.data(), dest.data(), nullptr, MS_BIND, nullptr);
+				mount_list += dest;
+				mount_list += '\n';
 			}
 		}
 	}
@@ -376,6 +379,9 @@ void SARCommon::patch_rootdir() {
 	src = xopen(ROOTOVL, O_RDONLY | O_CLOEXEC);
 	magic_mount(src, "");
 	close(src);
+	dest = xopen(ROOTMNT, O_WRONLY | O_CREAT | O_CLOEXEC);
+	write(dest, mount_list.data(), mount_list.length());
+	close(dest);
 }
 
 #define FSR "/first_stage_ramdisk"