Significantly broaden sepolicy.rule compatibility

Previously, Magisk uses persist or cache for storing modules' custom
sepolicy rules. In this commit, we significantly broaden its
compatibility and also prevent mounting errors.

The persist partition is non-standard and also critical for Snapdragon
devices, so we prefer not to use it by default.

We will go through the following logic to find the best suitable
non-volatile, writable location to store and load sepolicy.rule files:

Unencrypted data -> FBE data unencrypted dir -> cache -> metadata -> persist

This should cover almost all possible cases: very old devices have
cache partitions; newer devices will use FBE; latest devices will use
metadata FBE (which guarantees a metadata parition); and finally,
all Snapdragon devices have the persist partition (as a last resort).

Fix #3179

app/src/main/java/com/topjohnwu/magisk/core/model/module/LocalModule.kt

@@ -26,11 +26,17 @@ class LocalModule(path: String) : Module() {
         set(enable) {
             val dir = "$PERSIST/$id"
             if (enable) {
-                Shell.su("mkdir -p $dir", "cp -af $ruleFile $dir").submit()
                 disableFile.delete()
+                if (Const.Version.isCanary())
+                    Shell.su("copy_sepolicy_rules").submit()
+                else
+                    Shell.su("mkdir -p $dir", "cp -af $ruleFile $dir").submit()
             } else {
-                Shell.su("rm -rf $dir").submit()
                 !disableFile.createNewFile()
+                if (Const.Version.isCanary())
+                    Shell.su("copy_sepolicy_rules").submit()
+                else
+                    Shell.su("rm -rf $dir").submit()
             }
         }
 
@@ -38,11 +44,17 @@ class LocalModule(path: String) : Module() {
         get() = removeFile.exists()
         set(remove) {
             if (remove) {
-                Shell.su("rm -rf $PERSIST/$id").submit()
                 removeFile.createNewFile()
+                if (Const.Version.isCanary())
+                    Shell.su("copy_sepolicy_rules").submit()
+                else
+                    Shell.su("rm -rf $PERSIST/$id").submit()
             } else {
-                Shell.su("cp -af $ruleFile $PERSIST/$id").submit()
                 !removeFile.delete()
+                if (Const.Version.isCanary())
+                    Shell.su("copy_sepolicy_rules").submit()
+                else
+                    Shell.su("cp -af $ruleFile $PERSIST/$id").submit()
             }
         }
 

native/jni/core/bootstages.cpp

@@ -22,14 +22,15 @@ static bool safe_mode = false;
  * Setup *
  *********/
 
-#define DIR_IS(part)      (me->mnt_dir == "/" #part ""sv)
+#define MNT_DIR_IS(dir)   (me->mnt_dir == string_view(dir))
 #define SETMIR(b, part)   sprintf(b, "%s/" MIRRDIR "/" #part, MAGISKTMP.data())
 #define SETBLK(b, part)   sprintf(b, "%s/" BLOCKDIR "/" #part, MAGISKTMP.data())
 
 #define mount_mirror(part, flag) \
-else if (DIR_IS(part) && me->mnt_type != "tmpfs"sv && lstat(me->mnt_dir, &st) == 0) { \
+else if (MNT_DIR_IS("/" #part) && me->mnt_type != "tmpfs"sv && lstat(me->mnt_dir, &st) == 0) { \
 	SETMIR(buf1, part); \
 	SETBLK(buf2, part); \
+	unlink(buf2); \
 	mknod(buf2, S_IFBLK | 0600, st.st_dev); \
 	xmkdir(buf1, 0755); \
 	xmount(buf2, buf1, me->mnt_type, flag, nullptr); \
@@ -43,6 +44,16 @@ if (access("/system/" #part, F_OK) == 0 && access(buf1, F_OK) != 0) { \
 	LOGI("link: %s\n", buf1); \
 }
 
+#define link_orig_dir(dir, part) \
+else if (MNT_DIR_IS(dir) && me->mnt_type != "tmpfs"sv) { \
+	SETMIR(buf1, part); \
+	rmdir(buf1); \
+	xsymlink(dir, buf1); \
+	LOGI("link: %s\n", buf1); \
+}
+
+#define link_orig(part) link_orig_dir("/" #part, part)
+
 static bool magisk_env() {
 	LOGI("* Initializing Magisk environment\n");
 
@@ -98,7 +109,11 @@ static bool magisk_env() {
 		mount_mirror(product, MS_RDONLY)
 		mount_mirror(system_ext, MS_RDONLY)
 		mount_mirror(data, 0)
-		else if (SDK_INT >= 24 && DIR_IS(proc) && !strstr(me->mnt_opts, "hidepid=2")) {
+		link_orig(cache)
+		link_orig(metadata)
+		link_orig(persist)
+		link_orig_dir("/mnt/vendor/persist", persist)
+		else if (SDK_INT >= 24 && MNT_DIR_IS("/proc") && !strstr(me->mnt_opts, "hidepid=2")) {
 			xmount(nullptr, "/proc", nullptr, MS_REMOUNT, "hidepid=2,gid=3009");
 		}
 		return true;
@@ -109,9 +124,9 @@ static bool magisk_env() {
 		xsymlink("./system_root/system", buf1);
 		LOGI("link: %s\n", buf1);
 	}
-	link_mirror(vendor);
+	link_mirror(vendor)
-	link_mirror(product);
+	link_mirror(product)
-	link_mirror(system_ext);
+	link_mirror(system_ext)
 
 	// Disable/remove magiskhide, resetprop
 	if (SDK_INT < 19) {

native/jni/include/magisk.hpp

@@ -17,6 +17,7 @@
 extern std::string  MAGISKTMP;
 #define INTLROOT    ".magisk"
 #define MIRRDIR     INTLROOT "/mirror"
+#define RULESDIR    MIRRDIR "/sepolicy.rules"
 #define BLOCKDIR    INTLROOT "/block"
 #define MODULEMNT   INTLROOT "/modules"
 #define BBPATH      INTLROOT "/busybox"

native/jni/init/init.hpp

@@ -68,11 +68,12 @@ class MagiskInit : public BaseInit {
 protected:
 	auto_data<HEAP> self;
 	auto_data<HEAP> config;
-	std::string persist_dir;
+	std::string custom_rules_dir;
 
 	void mount_with_dt();
 	bool patch_sepolicy(const char *file);
 	void setup_tmp(const char *path);
+	void mount_rules_dir(const char *dev_base, const char *mnt_base);
 public:
 	MagiskInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {}
 };
@@ -114,10 +115,11 @@ public:
 class SecondStageInit : public SARBase {
 protected:
 	void early_mount() override;
-	void cleanup() override { /* Do not do any cleanup */ }
 public:
 	SecondStageInit(char *argv[]) : SARBase(argv, nullptr) {
 		LOGD("%s\n", __FUNCTION__);
+		// Do not unmount /sys and /proc
+		mount_list.clear();
 	};
 };
 

native/jni/init/mount.cpp

@@ -205,27 +205,89 @@ static void switch_root(const string &path) {
 	frm_rf(root);
 }
 
-static void mount_persist(const char *dev_base, const char *mnt_base) {
+void MagiskInit::mount_rules_dir(const char *dev_base, const char *mnt_base) {
-	string mnt_point = mnt_base + "/persist"s;
+	char path[128];
-	strcpy(blk_info.partname, "persist");
 	xrealpath(dev_base, blk_info.block_dev);
-	char *s = blk_info.block_dev + strlen(blk_info.block_dev);
+	xrealpath(mnt_base, path);
-	strcpy(s, "/persist");
+	char *b = blk_info.block_dev + strlen(blk_info.block_dev);
+	char *p = path + strlen(path);
+
+	auto do_mount = [&](const char *type) -> bool {
+		xmkdir(path, 0755);
+		bool success = xmount(blk_info.block_dev, path, type, 0, nullptr) == 0;
+		if (success)
+			mount_list.emplace_back(path);
+		return success;
+	};
+
+	// First try userdata
+	strcpy(blk_info.partname, "userdata");
+	strcpy(b, "/data");
+	strcpy(p, "/data");
 	if (setup_block(false) < 0) {
-		// Fallback to cache
+		// Try NVIDIA naming scheme
-		strcpy(blk_info.partname, "cache");
+		strcpy(blk_info.partname, "UDA");
-		strcpy(s, "/cache");
+		if (setup_block(false) < 0)
-		if (setup_block(false) < 0) {
+			goto cache;
-			// Try NVIDIA's BS
-			strcpy(blk_info.partname, "CAC");
-			if (setup_block(false) < 0)
-				return;
-		}
-		xsymlink("./cache", mnt_point.data());
-		mnt_point = mnt_base + "/cache"s;
 	}
-	xmkdir(mnt_point.data(), 0755);
+	// Try to mount with either ext4 or f2fs
-	xmount(blk_info.block_dev, mnt_point.data(), "ext4", 0, nullptr);
+	// Failure means either FDE or metadata encryption
+	if (!do_mount("ext4") && !do_mount("f2fs"))
+		goto cache;
+
+	strcpy(p, "/data/unencrypted");
+	if (access(path, F_OK) == 0) {
+		// FBE, need to use an unencrypted path
+		custom_rules_dir = path + "/magisk"s;
+	} else {
+		// Skip if /data/adb does not exist
+		strcpy(p, "/data/adb");
+		if (access(path, F_OK) != 0)
+			return;
+		// Unencrypted, directly use module paths
+		custom_rules_dir = string(mnt_base) + MODULEROOT;
+	}
+	goto success;
+
+cache:
+	// Fallback to cache
+	strcpy(blk_info.partname, "cache");
+	strcpy(b, "/cache");
+	strcpy(p, "/cache");
+	if (setup_block(false) < 0) {
+		// Try NVIDIA naming scheme
+		strcpy(blk_info.partname, "CAC");
+		if (setup_block(false) < 0)
+			goto metadata;
+	}
+	if (!do_mount("ext4"))
+		goto metadata;
+	custom_rules_dir = path + "/magisk"s;
+	goto success;
+
+metadata:
+	// Fallback to metadata
+	strcpy(blk_info.partname, "metadata");
+	strcpy(b, "/metadata");
+	strcpy(p, "/metadata");
+	if (setup_block(false) < 0 || !do_mount("ext4"))
+		goto persist;
+	custom_rules_dir = path + "/magisk"s;
+	goto success;
+
+persist:
+	// Fallback to persist
+	strcpy(blk_info.partname, "persist");
+	strcpy(b, "/persist");
+	strcpy(p, "/persist");
+	if (setup_block(false) < 0 || !do_mount("ext4"))
+		return;
+	custom_rules_dir = path + "/magisk"s;
+
+success:
+	// Create symlinks so we don't need to go through this logic again
+	strcpy(p, "/sepolicy.rules");
+	xsymlink(custom_rules_dir.data(), path);
 }
 
 void RootFSInit::early_mount() {
@@ -235,11 +297,6 @@ void RootFSInit::early_mount() {
 	rename("/.backup/init", "/init");
 
 	mount_with_dt();
-
-	xmkdir("/dev/mnt", 0755);
-	mount_persist("/dev/block", "/dev/mnt");
-	mount_list.emplace_back("/dev/mnt/persist");
-	persist_dir = "/dev/mnt/persist/magisk";
 }
 
 void SARBase::backup_files() {
@@ -337,8 +394,6 @@ void MagiskInit::setup_tmp(const char *path) {
 	xmkdir(MIRRDIR, 0);
 	xmkdir(BLOCKDIR, 0);
 
-	mount_persist(BLOCKDIR, MIRRDIR);
-
 	int fd = xopen(INTLROOT "/config", O_WRONLY | O_CREAT, 0);
 	xwrite(fd, config.buf, config.sz);
 	close(fd);

native/jni/init/rootdir.cpp

@@ -81,33 +81,6 @@ static void load_overlay_rc(const char *overlay) {
 	}
 }
 
-void RootFSInit::setup_rootfs() {
-	if (patch_sepolicy("/sepolicy")) {
-		auto init = raw_data::mmap_rw("/init");
-		init.patch({ make_pair(SPLIT_PLAT_CIL, "xxx") });
-	}
-
-	// Handle overlays
-	if (access("/overlay.d", F_OK) == 0) {
-		LOGD("Merge overlay.d\n");
-		load_overlay_rc("/overlay.d");
-		mv_path("/overlay.d", "/");
-	}
-
-	patch_init_rc("/init.rc", "/init.p.rc", "/sbin");
-	rename("/init.p.rc", "/init.rc");
-
-	// Create hardlink mirror of /sbin to /root
-	mkdir("/root", 0750);
-	clone_attr("/sbin", "/root");
-	link_path("/sbin", "/root");
-
-	// Dump magiskinit as magisk
-	int fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
-	write(fd, self.buf, self.sz);
-	close(fd);
-}
-
 bool MagiskInit::patch_sepolicy(const char *file) {
 	bool patch_init = false;
 	sepolicy *sepol = nullptr;
@@ -135,12 +108,14 @@ bool MagiskInit::patch_sepolicy(const char *file) {
 	sepol->magisk_rules();
 
 	// Custom rules
-	if (auto dir = open_dir(persist_dir.data()); dir) {
+	if (!custom_rules_dir.empty()) {
-		for (dirent *entry; (entry = xreaddir(dir.get()));) {
+		if (auto dir = open_dir(custom_rules_dir.data())) {
-			auto rule = persist_dir + "/" + entry->d_name + "/sepolicy.rule";
+			for (dirent *entry; (entry = xreaddir(dir.get()));) {
-			if (access(rule.data(), R_OK) == 0) {
+				auto rule = custom_rules_dir + "/" + entry->d_name + "/sepolicy.rule";
-				LOGD("Loading custom sepolicy patch: %s\n", rule.data());
+				if (access(rule.data(), R_OK) == 0) {
-				sepol->load_rule_file(rule.data());
+					LOGD("Loading custom sepolicy patch: %s\n", rule.data());
+					sepol->load_rule_file(rule.data());
+				}
 			}
 		}
 	}
@@ -229,9 +204,8 @@ void SARBase::patch_rootdir() {
 	}
 
 	setup_tmp(tmp_dir);
-	persist_dir = MIRRDIR "/persist/magisk";
-
 	chdir(tmp_dir);
+	mount_rules_dir(BLOCKDIR, MIRRDIR);
 
 	// Mount system_root mirror
 	struct stat st;
@@ -317,11 +291,55 @@ void SARBase::patch_rootdir() {
 	chdir("/");
 }
 
+#define TMP_MNTDIR "/dev/mnt"
+#define TMP_RULESDIR "/.backup/.sepolicy.rules"
+
+void RootFSInit::setup_rootfs() {
+	// Handle custom sepolicy rules
+	xmkdir(TMP_MNTDIR, 0755);
+	mount_rules_dir("/dev/block", TMP_MNTDIR);
+	// Preserve custom rule path
+	if (!custom_rules_dir.empty()) {
+		string rules_dir = "./" + custom_rules_dir.substr(sizeof(TMP_MNTDIR));
+		xsymlink(rules_dir.data(), TMP_RULESDIR);
+	}
+
+	if (patch_sepolicy("/sepolicy")) {
+		auto init = raw_data::mmap_rw("/init");
+		init.patch({ make_pair(SPLIT_PLAT_CIL, "xxx") });
+	}
+
+	// Handle overlays
+	if (access("/overlay.d", F_OK) == 0) {
+		LOGD("Merge overlay.d\n");
+		load_overlay_rc("/overlay.d");
+		mv_path("/overlay.d", "/");
+	}
+
+	patch_init_rc("/init.rc", "/init.p.rc", "/sbin");
+	rename("/init.p.rc", "/init.rc");
+
+	// Create hardlink mirror of /sbin to /root
+	mkdir("/root", 0750);
+	clone_attr("/sbin", "/root");
+	link_path("/sbin", "/root");
+
+	// Dump magiskinit as magisk
+	int fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
+	write(fd, self.buf, self.sz);
+	close(fd);
+}
+
 void MagiskProxy::start() {
+	// Mount rootfs as rw to do post-init rootfs patches
+	xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
+
+	// Backup stuffs before removing them
 	self = raw_data::read("/sbin/magisk");
 	config = raw_data::read("/.backup/.magisk");
-
+	char custom_rules_dir[64];
-	xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
+	custom_rules_dir[0] = '\0';
+	xreadlink(TMP_RULESDIR, custom_rules_dir, sizeof(custom_rules_dir));
 
 	unlink("/sbin/magisk");
 	rm_rf("/.backup");
@@ -331,6 +349,10 @@ void MagiskProxy::start() {
 	// Create symlinks pointing back to /root
 	recreate_sbin("/root", false);
 
+	if (custom_rules_dir[0])
+		xsymlink(custom_rules_dir, "/sbin/" RULESDIR);
+
+	// Tell magiskd to remount rootfs
 	setenv("REMOUNT_ROOT", "1", 1);
 	execv("/sbin/magisk", argv);
 }

scripts/boot_patch.sh

@@ -178,5 +178,8 @@ ui_print "- Repacking boot image"
 # Sign chromeos boot
 $CHROMEOS && sign_chromeos
 
+# Copy existing rules for migration
+$BOOTMODE && copy_sepolicy_rules
+
 # Reset any error code
 true

scripts/magisk_uninstaller.sh

@@ -15,7 +15,6 @@ TMPDIR=/dev/tmp
 
 INSTALLER=$TMPDIR/install
 CHROMEDIR=$INSTALLER/chromeos
-PERSISTDIR=/sbin/.magisk/mirror/persist
 
 # Default permissions
 umask 022
@@ -36,7 +35,12 @@ setup_flashable
 print_title "Magisk Uninstaller"
 
 is_mounted /data || mount /data || abort "! Unable to mount /data, please uninstall with Magisk Manager"
-is_mounted /cache || mount /cache 2>/dev/null
+if ! $BOOTMODE; then
+  # Mounting stuffs in recovery (best effort)
+  mount_name metadata /metadata
+  mount_name "cache cac" /cache
+  mount_name persist /persist
+fi
 mount_partitions
 
 api_level_arch_detect
@@ -141,7 +145,8 @@ ui_print "- Removing Magisk files"
 rm -rf \
 /cache/*magisk* /cache/unblock /data/*magisk* /data/cache/*magisk* /data/property/*magisk* \
 /data/Magisk.apk /data/busybox /data/custom_ramdisk_patch.sh /data/adb/*magisk* \
-/data/adb/post-fs-data.d /data/adb/service.d /data/adb/modules* $PERSISTDIR/magisk 2>/dev/null
+/data/adb/post-fs-data.d /data/adb/service.d /data/adb/modules* \
+/data/unencrypted/magisk /metadata/magisk /persist/magisk /mnt/vendor/persist/magisk
 
 if [ -f /system/addon.d/99-magisk.sh ]; then
   blockdev --setrw /dev/block/mapper/system$SLOT 2>/dev/null
@@ -158,7 +163,7 @@ if $BOOTMODE; then
   ui_print "********************************************"
   (sleep 8; /system/bin/reboot)&
 else
-  rm -rf /data/user*/*/*magisk* /data/app/*magisk*
+  rm -rf /data/data/*magisk* /data/user*/*/*magisk* /data/app/*magisk* /data/app/*/*magisk*
   recovery_cleanup
   ui_print "- Done"
 fi

scripts/util_functions.sh

@@ -152,6 +152,7 @@ recovery_cleanup() {
   fi
   umount -l /vendor
   umount -l /persist
+  umount -l /metadata
   for DIR in /apex /system /system_root; do
     if [ -L "${DIR}_link" ]; then
       rmdir $DIR
@@ -217,13 +218,13 @@ mount_name() {
   local FLAG=$3
   setup_mntpoint $POINT
   is_mounted $POINT && return
-  ui_print "- Mounting $POINT"
   # First try mounting with fstab
   mount $FLAG $POINT 2>/dev/null
   if ! is_mounted $POINT; then
-    local BLOCK=`find_block $PART`
+    local BLOCK=$(find_block $PART)
-    mount $FLAG $BLOCK $POINT
+    mount $FLAG $BLOCK $POINT || return
   fi
+  ui_print "- Mounting $POINT"
 }
 
 # mount_ro_ensure <partname(s)> <mountpoint>
@@ -266,18 +267,6 @@ mount_partitions() {
 
   # Allow /system/bin commands (dalvikvm) on Android 10+ in recovery
   $BOOTMODE || mount_apex
-
-  # Mount persist partition in recovery
-  if ! $BOOTMODE && [ ! -z $PERSISTDIR ]; then
-    # Try to mount persist
-    PERSISTDIR=/persist
-    mount_name persist /persist
-    if ! is_mounted /persist; then
-      # Fallback to cache
-      mount_name "cache cac" /cache
-      is_mounted /cache && PERSISTDIR=/cache || PERSISTDIR=
-    fi
-  fi
 }
 
 # loop_setup <ext4_img>, sets LOOPDEV
@@ -575,6 +564,41 @@ run_migrations() {
   done
 }
 
+copy_sepolicy_rules() {
+  # Remove all existing rule folders
+  rm -rf /data/unencrypted/magisk /metadata/magisk /persist/magisk /mnt/vendor/persist/magisk
+
+  # Find current active RULESDIR
+  local RULESDIR
+  local active_dir=$(magisk --path)/.magisk/mirror/sepolicy.rules
+  if [ -e $active_dir ]; then
+    RULESDIR=$(readlink -f $active_dir)
+  elif [ -d /data/unencrypted ] && ! grep ' /data ' /proc/mounts | grep -q 'dm-'; then
+    RULESDIR=/data/unencrypted/magisk
+  elif grep -q ' /cache ' /proc/mounts; then
+    RULESDIR=/cache/magisk
+  elif grep -q ' /metadata ' /proc/mounts; then
+    RULESDIR=/metadata/magisk
+  elif grep -q ' /persist ' /proc/mounts; then
+    RULESDIR=/persist/magisk
+  elif grep -q ' /mnt/vendor/persist ' /proc/mounts; then
+    RULESDIR=/mnt/vendor/persist/magisk
+  else
+    return
+  fi
+
+  # Copy all enabled sepolicy.rule
+  for r in /data/adb/modules*/*/sepolicy.rule; do
+    [ -f "$r" ] || continue
+    local MODDIR=${r%/*}
+    [ -f $MODDIR/disable ] && continue
+    [ -f $MODDIR/remove ] && continue
+    local MODNAME=${MODDIR##*/}
+    mkdir -p $RULESDIR/$MODNAME
+    cp -f $r $RULESDIR/$MODNAME/sepolicy.rule
+  done
+}
+
 #################
 # Module Related
 #################
@@ -620,9 +644,6 @@ is_legacy_script() {
 
 # Require OUTFD, ZIPFILE to be set
 install_module() {
-  local PERSISTDIR
-  command -v magisk >/dev/null && PERSISTDIR=$(magisk --path)/mirror/persist
-
   rm -rf $TMPDIR
   mkdir -p $TMPDIR
 
@@ -646,7 +667,7 @@ install_module() {
   MODPATH=$MODULEROOT/$MODID
 
   # Create mod paths
-  rm -rf $MODPATH 2>/dev/null
+  rm -rf $MODPATH
   mkdir -p $MODPATH
 
   if is_legacy_script; then
@@ -699,19 +720,15 @@ install_module() {
   fi
 
   # Copy over custom sepolicy rules
-  if [ -f $MODPATH/sepolicy.rule -a -e "$PERSISTDIR" ]; then
+  if [ -f $MODPATH/sepolicy.rule ]; then
-    ui_print "- Installing custom sepolicy patch"
+    ui_print "- Installing custom sepolicy rules"
-    # Remove old recovery logs (which may be filling partition) to make room
+    copy_sepolicy_rules
-    rm -f $PERSISTDIR/cache/recovery/*
-    PERSISTMOD=$PERSISTDIR/magisk/$MODID
-    mkdir -p $PERSISTMOD
-    cp -af $MODPATH/sepolicy.rule $PERSISTMOD/sepolicy.rule || abort "! Insufficient partition size"
   fi
 
   # Remove stuffs that don't belong to modules
   rm -rf \
   $MODPATH/system/placeholder $MODPATH/customize.sh \
-  $MODPATH/README.md $MODPATH/.git* 2>/dev/null
+  $MODPATH/README.md $MODPATH/.git*
 
   cd /
   $BOOTMODE || recovery_cleanup