platform_system_sepolicy/prebuilts/api/32.0/private/postinstall.te

typeattribute postinstall coredomain;
type postinstall_exec, system_file_type, exec_type, file_type;
domain_auto_trans(postinstall, otapreopt_chroot_exec, otapreopt_chroot)

allow postinstall rootfs:dir r_dir_perms;