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ROOT: Patching the boot partition (non-US only)

Table of Contents

On KaiOS 2.5.4 devices, such as the 6300 4G and 8000 4G, ADB and WebIDE can be used to install most third-party apps. However, apps with special ‘forbidden’ permissions are not allowed, including most BananaHackers apps with engmode-extension like Wallace Toolbox, which can be used to gain exclusive access of the phone. You also cannot make changes to the system. On the 2720 Flip and 800 Tough with KaiOS 2.5.2.2, with HMD/Nokia Mobile changing their release branches from dev-keys to release-keys, the situation is even worse as you cannot sideload at all.

This is because in order for WhatsApp’s VoIP feature to work on these KaiOS versions, a security module called SELinux[^4] is now set to be Enforced which checks and reverts system modifications on boot. To get total read-write access to the devices, you’ll now have to permanently root them by setting SELinux to Permissive mode.

The guide below is based on the main guide from BananaHackers website, but has been rewritten to make it easier to follow. The process will take somewhat considerable 30 minutes to an hour, so do this when you have enough time.

[!IMPORTANT] DISCLAIMER: This process will void your phone’s warranty, disable its ability to receive WhatsApp calls and over-the-air updates, but you can undo this if you save a copy of the original boot partition. However, you might also brick your phone if you make a mistake in the process, so proceed at your own risk and with caution! I won’t be responsible for any damages done to your phone by following these.

Remember, you don’t have to root your phone to do things that usually need root access e.g. you can use this fork of Luxferre’s AppBuster to disable apps from the launcher instead of deleting them with Wallace Toolbox. You can also install [Luxferre’s CrossTweak], a Wallace Toolbox alternative also made by Luxferre that does not need engmode-extension and therefore can be easily installed on KaiOS 2.5.4 devices.

Before proceeding: back up your data

Murphy’s Law states, “Anything that can go wrong, will go wrong”. It’s a proverb from the late 1940s, and while it may not be as academically accurate and influential as Newton’s laws of motion, it’s generally acknowledged in technology as a rule of thumb. Even if you do the best you can, things can unexpectedly go south, so it’s always good to prepare for the worst.

For backing up application data (excluding WhatsApp chats), system preferences and partition images, see Back up system partitions.

What we’ll need

andybalholm’s EDL cannot be used on 8000 4G and 6300 4G due to structural changes within GPT, which will result in an error AttributeError: 'gpt' object has no attribute 'partentries'. Did you mean: 'num_part_entries'?. Do note that the command structures used between bkerler’s and andybalholm’s are different, which we’ll mention below.

For the sake of convenience, move the Gerda Recovery image and the MBN file into the root of edl-3.1 or edl-master folder. If you need to have those in other folders, change the directory path accordingly.

If you’re on Linux, Python and ADB can be quickly set up by installing with your built-in package manager. We won’t be covering this here, as each Linux distro has its own way of installing from package manager.

Note for Arch Linux users: I’ve made an experimental root.sh that you can use to automate all 4 parts of the process (see the root of the repository) based on @Llixuma’s tutorial. Debian-based distro users stay tuned!

Part 1: Set up environment for EDL tools

This portion of the guide was taken from Development/EDL tools on BananaHackers Wiki so that you don’t have to switch tabs. Kudos to Cyan for the guides!

Linux

  1. Install Python from your operating system’s package manager e.g.
sudo apt-get install python pip3
  1. Then, open Terminal and type this to install the dependencies for EDL tools:
sudo -H pip3 install pyusb pyserial capstone keystone-engine docopt
  1. Switch your phone to EDL mode and connect it to your computer. Either:
    • if your phone is on, turn on debugging mode on your phone by dialing *#*#33284#*#*, connect it to your computer and type adb reboot edl in a command-line window.
    • if your phone is off, hold down * and # at the same time while inserting the USB cable to the phone.

In both cases, the phone’s screen should blink with a ‘enabled by KaiOS’ logo then become blank. This is normal behaviour letting you know you’re in EDL mode and you can proceed.

Additionally, if you have issue with device access:

macOS

  1. Follow the instructions to install Homebrew on its homepage. Basically just open Terminal and copy the long streak of code shown on the page, and type your password when prompted.

  2. While you’re in Terminal, type this into the command-line:

brew install python android-platform-tools libusb && pip3 install pyusb pyserial capstone keystone-engine docopt
  1. Switch your phone to EDL mode and connect it to your computer. Either:
    • if your phone is on, turn on debugging mode on your phone by dialing *#*#33284#*#*, connect it to your computer and type adb reboot edl in a command-line window.
    • if your phone is off, hold down * and # at the same time while inserting the USB cable to the phone.

In both cases, the phone’s screen should blink with a ‘enabled by KaiOS’ logo then become blank. This is normal behaviour letting you know you’re in EDL mode and you can proceed.

Windows

  1. Head over to Python’s official download page for Windows and download the correct installer for your architecture, or download the latest version of Python from Microsoft Store. If you’re downloading from Microsoft Store, skip to step 4.
  2. Proceed with installing Python as usual. If you choose to customize your installation, include pip. Don’t forget to tick the box next to “Add Python to PATH” to add Python as a global environment variable, otherwise you’ll have a hard time using Python to run scripts later on.
    • If you decide to customize your installation, choose to install pip and tick Add Python to environment variables.

Screenshot of an installation window for Python 3.9 showing two options, 'Install Now' and 'Customize installation', with the checkbox for 'Add Python 3.9 to PATH' being selected

  1. On Windows 10/11, typing python or python3 within Command Prompt/Windows Terminal will run the Microsoft Store version of Python. To override this default into running the locally installed version, toggle off App Installer (python.exe) and App Installer (python3.exe) under:
    • Windows 10: Settings → Apps → Apps & features → App execution aliases
    • Windows 11: Settings → Apps → Advanced app settings → App execution aliases
Demostration of Settings app on Windows 11. User is already on Apps page and clicking on Advanced app settings. User then clicks on App execution aliases, where the toggles for App Installer (python.exe) and App Installer (python3.exe) are turned off. Description says Apps can declare a name used to run the app from a command prompt. If multiple apps use the same name, choose which one to use.
  1. Open Command Prompt/Windows Terminal with administrator privileges and run this command to install the required dependencies for EDL:
pip3 install pyusb pyserial capstone keystone-engine docopt

Screenshot of a console window showing the successful process of collecting and downloading dependencies after typing the above command

  1. Extract the previously downloaded EDL package, open Drivers, Windows and run Qualcomm_Diag_QD_Loader_2016_driver.exe with administrator rights. Proceed with installation and leave everything as default, restart the computer if it prompts you to do so.

Screenshot of an installation window for Qualcomm's diagnostic driver, in which two radio buttons are shown labelled 'WWAN-DHCP is not used to get IPAddress' and 'ETHERNET-DHCP is used to get IPAddress' respectively. The first button is selected.

  1. Switch your phone to EDL mode and connect it to your computer. Either:
    • if your phone is on, turn on debugging mode on your phone by dialing *#*#33284#*#*, connect it to your computer and type adb reboot edl in a command-line window.
    • if your phone is off, hold down * and # at the same time while inserting the USB cable to the phone.

In both cases, the phone’s screen should blink with an ‘enabled by KaiOS’ logo then become blank. This is normal behaviour letting you know you’re in EDL mode and you can proceed.

  1. To replace the installed qcusbser driver with libusb-win32 for use with edl.py, download and open Zadig (do NOT use the version included in the EDL package). Tick Options, List All Devices and select QHSUSB__BULK (your device in EDL mode) in the main dropdown menu. In the target driver box—to which the green arrow is pointing—click the up/down arrows until you see libusb-win32 and then click Replace Driver.

9-frame GIF demostrating Zadig's main interface, List All Devices option being selected from Option menu, QHSUSB_BULK being selected from the main dropdown list, followed by the second label box on the Drivers line, to which the green arrow points, changed to 'libusb-win32 (v1.2.6.0)'. Two smaller up/down arrows are right next to that box.

[!NOTE] Windows will automatically create restore points on driver installation, as Zadig suggests in its tooltips. On older PCs, this might cause issues with driver configuration process being lengthened past the 5-minute mark. If Zadig aborts the process and hangs, kill Zadig with Task Manager, remove and re-insert the battery on the phone to exit and re-enter EDL mode, then try to install again.

  1. If you’re configuring the driver for the first time, an “USB Device Not Recognised” pop-up may appear. Exit EDL mode by removing and re-inserting the battery, then turn on the phone in EDL mode again.

Part 2: Obtaining the boot partition

Nokia 8000 4G and Nokia 6300 4G with bkerler’s EDL

Beware: due to the firehose loader being malfunctioned, the EDL tool only accepts one command each session, after which you’ll have to disconnect the phone and restart the phone in EDL mode. If you try to throw a second command, it’ll result in a bytearray index out of range error.

  1. Turn on the phone in EDL mode.
  2. Open the extracted EDL folder in a command-line shell. Flash the Gerda Recovery image to the recovery partition by typing:
python edl.py w recovery recovery-8110.img --loader=8k.mbn

If the progress bar stops at 99% (not earlier) and you get error 'usb.core.USBError: [Errno None] b'libusb0-dll:err [_usb_reap_async] timeout error\n' or usb.core.USBError: [Errno 60] Command timed out, this is false. Don’t mind the error and proceed with the next step.

  1. When finished, disconnect the phone from your computer and exit EDL mode by removing and re-inserting the battery.
  2. Then, hold down the top Power button and * to turn on the phone in recovery mode. Connect the phone to your computer again.

[!WARNING] Be careful not to boot into system at this point! As stated above, while SELinux is still in Enforced mode, it’ll try to revert all system modifications on startup, in this case, the custom recovery image we’ve just flashed will be overwritten by the stock one. If you accidentally start into normal mode (with the usual Nokia chime), you’ll have to start over from step 1.

Don’t worry if this boots into a white screen: this is because the display driver for the Nokia 8110 4G included in the recovery image are not compatible with the display of 8000 4G/6300 4G.

Check if ADB can recognise the phone by typing adb devices into the command-line.

  1. Navigate the command-line to the extracted platform-tools folder (if needed) and pull the boot image from the phone to the current directory on your computer with ADB by typing:
adb pull /dev/block/bootdevice/by-name/boot boot.img

You should now see /dev/block/bootdevice/by-name/boot: 1 file pulled, 0 skipped. and have a copy of the boot partition with the size of 32.0MB (32,768KB). Fetched boot image will be saved to the current directory.

  1. Reboot the phone into normal mode by typing adb reboot into the command-line, or remove and re-insert the battery. Our custom Gerda Recovery partition will now be overwritten by the default one.

You can disconnect the phone from your computer for now.

Nokia 2720 Flip and Nokia 800 Tough with andybalholm’s EDL

Unlike the 6300 4G and 8000 4G, our phones’ EDL loader properly works with both reading and writing, so the steps are more straightforward.

  1. Switch your phone to EDL mode and connect it to your computer. Either:
    • if your phone is on, turn on debugging mode on your phone by dialing *#*#33284#*#*, connect it to your computer and type adb reboot edl in Command Prompt/Terminal;
    • if your phone is off, hold down both volume keys on the side (2720 Flip) or both D-Pad Up and Down keys (800 Tough) at the same time while inserting the USB cable to the phone.

In both cases, the phone’s screen should blink with a ‘Powered by KaiOS’ logo then go blank. This is normal behaviour letting you know you’re in EDL mode and you can proceed.

  1. Open the extracted EDL folder in a command-line shell. Extract the boot partition of the phone to the current directory on your computer by typing either of these commands depending on which file you have:
python edl.py -r boot boot.img -loader 2720.mbn

python edl.py -r boot boot.img -loader 800t.mbn
  1. When finished, reboot the phone into normal operation by typing either of these into the command-line, or remove and re-insert the battery:
python edl.py -reset -loader 2720.mbn

python edl.py -reset -loader 800t.mbn

You can disconnect the phone from your computer for now.

[!WARNING] Copy and keep the original boot partition somewhere safe in case you need to restore to the original state for over-the-air updates or re-enabling WhatsApp calls.

Part 3: Patching the boot partition

Automatic patching with 8k-boot-patcher

  1. Download and install Docker Desktop. Once set up, open the program, click Accept on this box and let the Docker Engine start before exiting.

Screenshot of a window titled as ‘Docker Subscription Service Agreement’ which declares that you will have to accept Docker’s Subscription Service Agreements, Data Processing Agreement and Data Privacy Policy in order to use the program, and the free scope of it is limited to personal and small business uses. The window also lists the options to view the full agreements, accept them or reject and close the program.

  1. Use Git to clone/download the boot patcher toolkit by typing this into Command Prompt/Terminal. This will download the toolkit and have Docker set it up. Do not omit the dot/period at the end of this command, this tells Docker where our downloaded toolkit are located on the system.
git clone https://gitlab.com/suborg/8k-boot-patcher.git && cd 8k-boot-patcher && docker build -t 8kbootpatcher .

Screenshot of a macOS Terminal window showing some logs in purple text after typing the command above

  1. Copy the boot.img file we’ve just pulled from our phone to the desktop and do not change its name. Type this into Command Prompt/Terminal to run the patching process:
    • Windows: docker run --rm -it -v %cd%/Desktop:/image 8kbootpatcher
    • macOS/Linux: docker run --rm -it -v ~/Desktop:/image 8kbootpatcher
$ docker run --rm -it -v ~/Desktop:/image 8kbootpatcher

Boot image found, patching...
writing boot image config in bootimg.cfg
extracting kernel in zImage
extracting ramdisk in initrd.img
charger
data
[...]
ueventd.qcom.rc
ueventd.rc
verity_key
4037 blocks
4979 blocks
reading config file bootimg.cfg
reading ramdisk from myinitrd.img
Writing Boot Image boot.img
Boot image patched!

That’s it! On your desktop there will be two new image files, the modified boot.img and the original boot-orig.img. You can now head to part 4.

Screenshot of boot.img and boot-orig.img files as shown on desktop

Manual patching with Android Image Kitchen

  1. Extract the Android Image Kitchen tools and copy the boot image we’ve just obtained over to the root of the extracted folder.

Screenshot of a list of folders and files contained in the extracted Android Image Kitchen folder

  1. Open the folder in Command Prompt/Terminal and type unpackimg boot.img. This will split the image file and unpack the ramdisk to their subdirectories.

Screenshot of a Windows Command Prompt window showing some logs of the boot partition extracting process after typing the command above

[!WARNING] Be sure to edit the files correctly, else the phone won’t boot!

  1. Let the editing begin! First, open ramdisk/default.prop using Notepad++ and change:
    • line 7: ro.secure=1 → ro.secure=0
    • line 8: security.perf_harden=1 → security.perf_harden=0
    • line 10: ro.debuggable=0 → ro.debuggable=1
@@ -4,9 +4,9 @@
  ro.sw.release.date=21-08-13
  ro.build.version.fih=20.00.17.01
  ro.build.elabel=false
- ro.secure=1
- security.perf_harden=1
+ ro.secure=0
+ security.perf_harden=0
  ro.allow.mock.location=0
- ro.debuggable=0
+ ro.debuggable=1
  ro.adb.secure=0
  ro.zygote=zygote32

Screenshot of the modified content of the default.prop file

  1. Open ramdisk/init.qcom.early_boot.sh in Notepad++ and add setenforce 0 as a new line at the end of the file.
@@ -312,14 +312,14 @@
  else
      # nand configuration
      if [ -e $nand_file ]
      then
          if grep ${partition_name} $nand_file
          then
              gps_enabled=false
          fi
      fi
  fi

  setprop ro.gps.enabled $gps_enabled
+ setenforce 0

Screenshot of the modified content of the init.qcom.early_boot.sh file

  1. Go back to the root Android Image Kitchen folder and open split_img/boot.img-cmdline in Notepad++. Without adding a new line, scroll to the end of the first line and append androidboot.selinux=permissive enforcing=0.

Screenshot of the modified content of the boot.img-cmdline file

  1. Open ramdisk/init.rc (NOT ramdisk/init) and delete line 393 setprop selinux.reload_policy 1 or mark a comment as shown. This will ultimately prevent SELinux from overwriting the policy changes we made above.

If you want to know why I put an additional line to set /sys/module/lowmemorykiller/parameters/enable_lmk to 0, see [Expanding RAM with swapfile].

@@ -390,7 +390,6 @@
  setusercryptopolicies /data/user

  # Reload policy from /data/security if present.
- setprop selinux.reload_policy 1

  # Set SELinux security contexts on upgrade or policy update.
  restorecon_recursive /data
@@ -418,9 +418,10 @@
  # Memory management.  Basic kernel parameters, and allow the high
  # level system server to be able to adjust the kernel OOM driver
  # parameters to match how it is managing things.
+ write /sys/module/lowmemorykiller/parameters/enable_lmk 0
  write /proc/sys/vm/overcommit_memory 1
  write /proc/sys/vm/min_free_order_shift 4
  chown root system /sys/module/lowmemorykiller/parameters/adj
  chmod 0664 /sys/module/lowmemorykiller/parameters/adj
  chown root system /sys/module/lowmemorykiller/parameters/minfree
  chmod 0664 /sys/module/lowmemorykiller/parameters/minfree

Screenshot of the modified content of the init.rc file, with line 393 marked as comment which has the same effects as deleting the line altogether, and line 421 added to disable the Low Memory Killer module

  1. And that’s a wrap! Open the root Android Image Kitchen folder in a command-line window and type repackimg to package our modified boot partition.

Screenshot of a Windows Command Prompt window showing some logs of the fully successful boot partition process after typing the above command

If you happen to encounter an error during the signing process, that’s likely because the process uses java to power the boot-signer.jar sequence and you don’t have it installed. The image will still be packaged and ready for flashing, but if you’re a perfectionist, you can install JRE and try again.

If the newly packaged image is barely over 1/3 the size of the original image, it’s a normal behaviour and you can proceed.

Part 4: Flashing the modified boot partition

  1. Turn on your phone in EDL mode and connect it to your computer.
  2. Move the newly created boot.img, unsigned-new.img or image-new.img to the EDL tools folder and open Command Prompt/Terminal within it. From here type either of these commands depending on which image file you have:
python edl.py w boot boot.img --loader=8k.mbn

python edl.py w boot unsigned-new.img --loader=8k.mbn

python edl.py w boot image-new.img --loader=8k.mbn

For Nokia 2720 Flip and Nokia 800 Tough with andybalholm’s EDL:

python edl.py -w boot boot.img -loader 2720.mbn

python edl.py -w boot boot.img -loader 800t.mbn

Again, if the progress bar stops at 99% and you get a timeout error, this is because the phone doesn’t send any indicator information back to the EDL tool when in fact the image has been successfully written. Don’t mind the error and go on with the next step.

  1. Restart the phone to normal operation mode by typing python edl.py reset. And we’re done!

Next steps

Screenshot of a WebIDE window in which the location of Device Preferences is highlighted in the right pane and the value of devTools.apps.forbiddenPermissions has been emptied

echo -n 1 > /data/enforce
mount -o bind /data/enforce /sys/fs/selinux/enforce

If you wish to revert all changes you’ve made, connect your phone to the computer in EDL mode, move the original boot image file to edl-3.1 or edl-master folder, open Command Prompt/Terminal within the folder and type:

python edl.py w boot boot.img --loader=8k.mbn
python edl.py reset