32 vs 64 bits

32 vs 64 bits

[Nicolas Dichtel]

Hi all,

I'm trying to understand why the following commit has been done:

http://git.netfilter.org/cgi-bin/gitweb.cgi?p=iptables.git;a=commitdiff;h=7d5cc229064b0e718046b9ecaebad3426dfff15f

   Removes KERNEL_64_USERSPACE_32

   Yasuyuki KOZAKAI [Sat, 30 Jun 2007 10:47:57 +0000 (10:47 +0000)]

   The recent kernel has compat layer for iptables. It doesn't have
   compat layer for libipq and ip6tables, but ip6tables with
   KERNEL_64_USERSPACE_32 is still broken. We should fix kernel instead of
   fixing them if and when we want use their 32bit binary with 64bit kernel.

Where is the compat layer? If I look in a recent kernel, it seems that 
ip_queue.h still uses long and is broken.
http://git.kernel.org/?p=linux/kernel/git/davem/net-next-2.6.git;a=blob;f=include/linux/netfilter_ipv4/ip_queue.h;hb=59b8bfd8fd608821e5addc9f4682c7f2424afd8c

Am I wrong?
If yes, what is the right way to fix this? Updating the API?


Thank you,
Nicolas

Re: 32 vs 64 bits

[Jan Engelhardt]

On Thursday 2009-03-26 15:26, Nicolas Dichtel wrote:

> Hi all,
>
> I'm trying to understand why the following commit has been done:
>
> http://git.netfilter.org/cgi-bin/gitweb.cgi?p=iptables.git;a=commitdiff;h=7d5cc229064b0e718046b9ecaebad3426dfff15f
>
>  Removes KERNEL_64_USERSPACE_32
>
>  Yasuyuki KOZAKAI [Sat, 30 Jun 2007 10:47:57 +0000 (10:47 +0000)]
>
>  The recent kernel has compat layer for iptables. It doesn't have
>  compat layer for libipq and ip6tables, but ip6tables with
>  KERNEL_64_USERSPACE_32 is still broken. We should fix kernel instead of
>  fixing them if and when we want use their 32bit binary with 64bit kernel.
>
> Where is the compat layer?

For example, net/netfilter/xt_MARK.c there are some regions with
"#ifdef CONFIG_COMPAT". People used to use the C type "long", which
has different sizes across different platforms, leading to a mess
and evidently the compat conversion functions. Many of the Xtables
modules do not suffer from this and hence there is not that much
compat code left.

> If I look in a recent kernel, it seems that
> ip_queue.h still uses long and is broken.
> [linux/netfilter_ipv4/ip_queue.h]

Indeed this seems so.

> Am I wrong?
> If yes, what is the right way to fix this? Updating the API?

Use libnetfilter_queue ;-)