xfrm_get_mode
inner_mode = xfrm_get_mode(x->props.mode, x->sel.family);
inner_mode = xfrm_get_mode(x->props.mode, x->props.family);
inner_mode_iaf = xfrm_get_mode(x->props.mode, iafamily);
outer_mode = xfrm_get_mode(x->props.mode, family);