try to jail yay (and similar aur helpers)

jail.sh

#! /bin/sh

## custom nsjail for yay

BASE_JAIL=(
  --symlink /usr/bin:/bin
  --symlink /usr/lib:/lib64
  --bindmount_ro /dev/null
  --bindmount_ro /usr
  --bindmount_ro /etc/passwd
  --bindmount_ro /etc/group
  --bindmount_ro /etc/ssl/certs/ca-certificates.crt
  --bindmount_ro /etc/resolv.conf
  --bindmount_ro /etc/nsswitch.conf
  --tmpfsmount /tmp
  --tmpfsmount $HOME
  --cwd $HOME
  --env HOME
  --quiet
)

INTERACTIVE=(
  --env TERM
  --env EDITOR
  --skip_setsid
)

SECCOMP=(
  # disable dmesg
  --seccomp_string "ERRNO(0) { syslog } DEFAULT ALLOW"
)

OTHER=(
  --disable_proc
  --rlimit_as max
  --rlimit_fsize max
  --rlimit_nofile max
  --disable_clone_newnet
)

YAY=(
  --bindmount_ro /etc/makepkg.conf
  --bindmount_ro /etc/pacman.conf
  --bindmount_ro /etc/pacman.d/
  --bindmount_ro /var/lib/pacman
  --bindmount_ro ~/.config/yay/
  --bindmount ~/.cache/yay/
)

nsjail "${BASE_JAIL[@]}" "${INTERACTIVE[@]}" "${SECCOMP[@]}" "${OTHER[@]}" "${YAY[@]}" -- /usr/bin/bash
#nsjail "${BASE_JAIL[@]}" "${SECCOMP[@]}" "${OTHER[@]}" "${YAY[@]}" -- /usr/bin/yay "$@"