On Thu, Jul 26, 2018 at 10:49:59AM +0200, Florian Westphal wrote: > Dmitry Safonov <dima@xxxxxxxxxx> wrote: > > So, here I add a compatible layer to xfrm. > > As xfrm uses netlink notifications, kernel should send them in ABI > > format that an application will parse. The proposed solution is > > to save the ABI of bind() syscall. The realization detail is > > to create kernel-hidden, non visible to userspace netlink groups > > for compat applications. > > Why not use exisiting netlink support? > Just add the 32bit skb to skb64->frag_list and let > netlink find if tasks needs 64 or 32 one. > > It only needs this small fix to properly signal the end of a dump: > https://marc.info/?l=linux-netdev&m=126625240303351&w=2 > > I had started a second attempt to make xfrm compat work, > but its still in early stage. > > One link that might still have some value: > https://git.breakpoint.cc/cgit/fw/net-next.git/commit/?h=xfrm_config_compat_07&id=f64430e6d9e297f3990f485a4832e273751b9869 > (compat structure definitions with BUILD_BUG_ON checking) > > My plan was to make xfrm compat work strictly as shrinker (64->32) > and expander (32->64), i.e. no/little changes to exisiting code and > pass all "expanded" skbs through existing xfrm rcv functions. I agree here with Florian. The code behind this ABI is already complicated. Please stay away from generic code a much as possible. Generic and compat code should be clearly separated. -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
