Chroot on Android

Credit to https://github.com/ELWAER-M/Chroot-on-termux for the original script

Content

• Good to Mention
• Choosing a rootfs
• Extracting the rootfs
• Making a script to launch the chroot environment
• Troubleshooting
  • Fixing apt under debian based ditros
  • Fixing network issues

Good to Mention

• You need a rooted phone for that
• I've used here a Samsung S10+ phone running Lineage OS 19.1
• If any damage happens to your phone, you are all responsible for it!

Choosing a rootfs

the rootfs architecture have to match with your device architecture too, to know what architecture your phone have run:

$ uname -m
  aarch64

(e.g. aarch64, armv7l).

Extracting the rootfs

Any location under /data should be good (because it formatted as ext4)

e.g.

$ mkdir chroot #or anything else
$ sudo tar xfp /sdcard/Download/rootfs.tar.xz -C /data/ubuntu #to keep the files permissions

Making a script to launch the chroot environment

Use nano or any text editor you like for that:

$ nano run-chroot.sh

simple example:

#!/bin/sh

# fix /dev mount options
mount -o remount,dev,suid /data

mount --bind /dev /data/ubuntu/dev
mount --bind /sys /data/ubuntu/sys
mount --bind /proc /data/ubuntu/proc
mount --bind /dev/pts /data/ubuntu/dev/pts


export PATH=/bin:/sbin:/usr/bin:/usr/sbin
export TERM=$TERM
export TMPDIR=/tmp

chroot /data/ubuntu/ /bin/su - root

then change the file permissions to executable:

$ chmod +x run-chroot.sh

you have to run it as root:

$ sudo ./run-chroot.sh

Troubleshooting

Fixing apt under debian based ditros

usermod -g 3003 _apt

Fixing network issues

you have to add a DNS to resolv.conf:

echo "nameserver 8.8.8.8" > /etc/resolv.conf

then you need to add android root groups:

groupadd -g 3001 aid_bt
groupadd -g 3002 aid_bt_net
groupadd -g 3003 aid_inet
groupadd -g 3004 aid_net_raw
groupadd -g 3005 aid_admin

then add those groups to the user you using:

usermod -a -G aid_bt,aid_bt_net,aid_inet,aid_net_raw,aid_admin root