pivot_root jail crashes termux

[maakiono]

Hello, Ive been experimenting running a graphically accelerated DE with termux-x11 with the intent of running flatpak apps and running steam, both of which absolutely refuse to work under a chroot as they rely on user namespaces

I run a custom built kernel with kernelsu and support for user namespaces

I have now come up with a combination of pivot_root and unshare to setup a chroot equivalent with chroot but I've noticed that it causes termux to unable to execve() any files and returns a file not found error

This is the script I use to launch the jail

#!/bin/bash

pkill -9 -f "app_process ,* com.termux.x11"
killall -9 termux-x11 Xwayland pulseaudio termux-wake-lock

am start --user 0 -n com.termux.x11/com.termux.x11.MainActivity

XDG_RUNTIME_DIR=${TMPDIR}
unset LD_PRELOAD
export ROOTFSPATH=$(realpath ~/.chroot)

sudo mount -o remount,dev,suid /data

echo "Starting Termux-x11..."
termux-x11 :0 -dpi 300 &>/dev/null & pulseaudio --start --load="module-native-protocol-tcp auth-ip-acl=127.0.0.1 auth-anonymous=1" --exit-idle-time=-1 &>/dev/null & sleep 1


echo "Starting Linux..."

su -c unshare -p -m -f sh -c \
"echo 'init';\
	mount --bind .chroot .chroot;\
	busybox pivot_root .chroot .chroot/old_root;\
	/usr/bin/mount proc -t proc /proc;\
	/usr/bin/mount sys -t sysfs /sys;\
	/usr/bin/mount --bind /old_root/dev /dev;\
	/usr/bin/mount --bind /old_root/dev/pts /dev/pts;\
	/usr/bin/mount --bind /old_root/storage/emulated/0 /sdcard;\
	/usr/bin/mount --bind /old_root$PREFIX/tmp/ /tmp/;\
	/usr/bin/su -l"
	
pkill -9 -f "app_process .* com.termux.x11"
killall -9 termux-x11 Xwayland pulseaudio termux-wake-lock

[maakiono]

Here is a short video of the same

screen-20240828-232122.mp4

[maakiono]

Logcat of the same

28_08-23-26-35_679.log

[maakiono]

Ive decided to open a bug report(#4130) on this as I'm completely lost if this is oversight of my own or a issue with termux