Procedure to modify a product.img.lz4 used by Samsung Android phones with Android 10

samsung-android-pack-repack.sh

ANDROID 10 SAMSUNG IMG PACK/REPACK - UBUNTU 18.10 COSMIC
[BOOTLOADER UNLOCKED IS REQUIRED - FIRST UNLOCK BOOTLOADER]
-----------------------------------------------------------
/etc/apt/sources.list

deb http://old-releases.ubuntu.com/ubuntu/ cosmic main universe restricted multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ cosmic main universe restricted multiverse

deb http://old-releases.ubuntu.com/ubuntu/ cosmic-security main universe restricted multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ cosmic-security main universe restricted multiverse

deb http://old-releases.ubuntu.com/ubuntu/ cosmic-updates main universe restricted multiverse
deb-src http://old-releases.ubuntu.com/ubuntu/ cosmic-updates main universe restricted multiverse
==============================================

+------------------------------------------------------------------------------------------------------------------------------+
## SELINUX NOTE *** (. after linux permissions)
Modified files (in the image) must have selinux permissions, otherwise are ignored ( -rw-r--r--. <--- must have a dot at the end )
Before modify a file or replace it, read the actual permissions from that file or from a file in the same folder
with this command:

getfattr -n security.selinux cscfeature.xml
 ---->  security.selinux="u:object_r:vendor_configs_file:s0"

and set it with this command:
setfattr -n security.selinux -v "u:object_r:vendor_configs_file:s0" cscfeature.xml

+------------------------------------------------------------------------------------------------------------------------------+

[BE ROOT]
sudo -s

===================================================================
INSTALLATION OF SIMG2IMG - IMG2SIMG - AVBTOOL - getfattr - setfattr
===================================================================

apt-get install liblz4-tool android-tools-fsutils openjdk-11-jre-headless build-essential make gcc zlib1g-dev git -y
apt-get install attr policycoreutils policycoreutils-python-utils -y

cd ~
wget https://github.com/fei-ke/OmcTextDecoder/releases/download/v0.3/omc-decoder.jar
###DECODE EXAMPLE
###java -jar /root/omc-decoder.jar    -i cscfeature.xml -o cscfeature_decoded.xml
###ENCODE EXAMPLE
###java -jar /root/omc-decoder.jar -e -i cscfeature_decoded.xml -o cscfeature.xml

git clone https://github.com/anestisb/android-simg2img.git
cd android-simg2img
make

cd ~
git clone https://android.googlesource.com/platform/external/avb

===================================================================
PACK/REPACK PRODUCT.IMG.LZ4 (FOR EDITING CSCFEATURE.XML)
===================================================================
[FIRST OF ALL CREATE A BACKUP OF YOUR DATA, A COMPLETE WIPE IS REQUIRED]

cd ~

# VBMETA CREATION [to disable Android Verified Boot (this is required for modify product.img.lz4)]
cd ~/avb
./avbtool make_vbmeta_image --flags 2 --padding_size 4096 --output ~/vbmeta.img
lz4 -B6 --content-size ~/vbmeta.img ~/vbmeta.img.lz4

cd ~

[COPY THE FILE product.img.lz4 in ~ (extract it from the CSC...tar.md5)]

unlz4 ~/product.img.lz4 ~/product.img
~/android-simg2img/simg2img ~/product.img ~/product.img.raw
mkdir ~/product
mount -t ext4 -o loop ~/product.img.raw ~/product

[===================== modify what you want in ~/product *** see SELINUX NOTE above =====================]

## (replace ITV with your SIM country code)

# this is to remove preloaded apps (if you like)
rm ~/product/preload/ITV/hidden_app/*
echo "" > ~/product/omc/ITV/etc/hidden_apks_list.txt

# CSC EDIT
cd ~/product/omc/ITV/conf

# DECODE CSC
java -jar ~/omc-decoder.jar -i cscfeature.xml -o cscfeature_decoded.xml
vi cscfeature_decoded.xml

       # modify xml code as your needs
       <CscFeature_......>....</CscFeature_......>

# ENCODE CSC
getfattr -n security.selinux cscfeature.xml
    ----> we get: security.selinux="u:object_r:vendor_configs_file:s0" [write down the part between double quotes]

rm cscfeature.xml [ write down the permissions of the file with: ls -l cscfeature.xml ] should be these: -rw-r--r--.
java -jar ~/omc-decoder.jar -e -i cscfeature_decoded.xml -o cscfeature.xml
rm cscfeature_decoded.xml
# between the double quotes insert the part found with getfattr
setfattr -n security.selinux -v "u:object_r:vendor_configs_file:s0" cscfeature.xml
# check the permissions are the same of the original cscfeature.xml
ls -l cscfeature.xml

[======================================== image modifications end here ============================]

# NOW WE REPACK THE IMAGE
cd ~
rm -rf ~/MOD
mkdir ~/MOD
umount ~/product
~/android-simg2img/img2simg ~/product.img.raw ~/MOD/product.img
lz4 -B6 --content-size ~/MOD/product.img ~/MOD/product.img.lz4


Copy ~/MOD/product.img.lz4 on Windows (we are going to flash with odin)
Copy the created ~/vbmeta.img.lz4 on Windows
Extract with 7zip the CSC.tar.md5 containing the original product.img.lz4 and the other .img.lz4 files
Replace product.img.lz4 with the ~/MOD/product.img.lz4
Add the created ~/vbmeta.img.lz4 together with the others .img.lz4
Select all tar extracted contents and recreate the CSC.tar with the same content of CSC.tar.md5 + vbmeta.img.lz4 (select all files -> 7zip -> add to.. -> CSC.tar)
Flash CSC with CSC.tar with Odin 3.14 flash it together with the stock AP, BL and CP downloaded with the original CSC.tar.md5

Perform a complete WIPE to use the new CSC information (on the reboot, the phone will start automatically the recovery, select WIPE and reboot)

Restart the phone. If you see the SAMSUNG logo at the center logo wait 5 minutes for the first start.