Create /data_mirror in init.rc
Mount a tmpfs on top of it, and serve as a mirror of /data/data
and /data/user_de, which will be used when zygote forks and
overlay its CE and DE storage to prevent app can see other applications.
Also, changed /data/user/0 from symlink to bind mount, so
/data_mirror/data_ce/null can just bind to /data/user directly.
Bug: 143937733
Test: Directories are created and mounted
Change-Id: Ic72c47c9d3dc0ffc98510f5bb351eccf76524232
diff --git a/rootdir/Android.mk b/rootdir/Android.mk
index ebc0cde..2dbdb60 100644
--- a/rootdir/Android.mk
+++ b/rootdir/Android.mk
@@ -72,7 +72,7 @@
#
# create some directories (some are mount points) and symlinks
LOCAL_POST_INSTALL_CMD := mkdir -p $(addprefix $(TARGET_ROOT_OUT)/, \
- dev proc sys system data odm oem acct config storage mnt apex debug_ramdisk \
+ dev proc sys system data data_mirror odm oem acct config storage mnt apex debug_ramdisk \
linkerconfig $(BOARD_ROOT_EXTRA_FOLDERS)); \
ln -sf /system/bin $(TARGET_ROOT_OUT)/bin; \
ln -sf /system/etc $(TARGET_ROOT_OUT)/etc; \
diff --git a/rootdir/init.rc b/rootdir/init.rc
index 2ec0669..b89c45e 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -650,12 +650,35 @@
mkdir /data/user 0711 system system encryption=None
mkdir /data/user_de 0711 system system encryption=None
- symlink /data/data /data/user/0
+
+ # Unlink /data/user/0 if we previously symlink it to /data/data
+ rm /data/user/0
+
+ # Bind mount /data/user/0 to /data/data
+ mkdir /data/user/0 0700 system system encryption=None
+ mount none /data/data /data/user/0 bind rec
# Special-case /data/media/obb per b/64566063
mkdir /data/media 0770 media_rw media_rw encryption=None
mkdir /data/media/obb 0770 media_rw media_rw encryption=Attempt
+ # A tmpfs directory, which will contain all apps CE DE data directory that
+ # bind mount from the original source.
+ chown root root /data_mirror
+ chmod 0700 /data_mirror
+ mount tmpfs tmpfs /data_mirror mode=0700,uid=0,gid=1000 nodev noexec nosuid
+ restorecon /data_mirror
+ mkdir /data_mirror/data_ce 0700 root root
+ mkdir /data_mirror/data_de 0700 root root
+
+ # Create CE and DE data directory for default volume
+ mkdir /data_mirror/data_ce/null 0700 root root
+ mkdir /data_mirror/data_de/null 0700 root root
+
+ # Bind mount CE and DE data directory to mirror's default volume directory
+ mount none /data/user /data_mirror/data_ce/null bind rec
+ mount none /data/user_de /data_mirror/data_de/null bind rec
+
mkdir /data/cache 0770 system cache encryption=Require
mkdir /data/cache/recovery 0770 system cache
mkdir /data/cache/backup_stage 0700 system system
