Mounting /system partition in read-write mode in Android

Any hacker needs full access to the system files to play with the system. Andoid /system partition is read-only by default. Here is an HOWTO to mount it in read-write mode. It is assumed that you have installed android SDK in your workstation. We use adb tool in tools directory of SDK.

1. Identifying the /system partition device file: Follow the sample session.

C:\android-sdk-windows-1.1_r1\tools>adb shell

$ su

# mount
rootfs / rootfs ro 0 0
tmpfs /dev tmpfs rw,mode=755 0 0
devpts /dev/pts devpts rw,mode=600 0 0
proc /proc proc rw 0 0
sysfs /sys sysfs rw 0 0
tmpfs /sqlite_stmt_journals tmpfs rw,size=4096k 0 0
/dev/block/mtdblock3 /system yaffs2 ro 0 0
/dev/block/mtdblock5 /data yaffs2 rw,nosuid,nodev 0 0
/dev/block/mtdblock4 /cache yaffs2 rw,nosuid,nodev 0 0
/dev/block/mmcblk0p1 /sdcard vfat rw,dirsync,nosuid,nodev,noexec,uid=1000,gid=1000,fmask=0711,dmask=0700,codepage=cp437,iocharset=iso8859-1,utf8 0 0

/dev/block/mtdblock3 is the /system partition device file.

2. Remounting the /system in read-write mode:

# mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system

3. If necessary set read-write permission to any directory under /system. Don’t forget to revert back once you get what you are intended to do.

# chmod 777 /system/fonts

4. Exit the hacker session

# exit

$ exit

Enjoy the freedom of /system.