Re: ipv4: net namespace does not inherit network configurations

[zhuyj]

Hi, Miller && Cong

Can we merge this patch into kernel mainline? since the independence
between ipv4 and ipv6 is inconsistent even in the latest linux 
kernel(3.17-rc7),
that is, the net namespace is independent in ipv6 while it is not in ipv4.

Thanks a lot.
Zhu Yanjun

On 07/30/2014 01:48 AM, Cong Wang wrote:
> On Tue, Jul 29, 2014 at 2:29 AM, zhuyj <zyjzyj2000@xxxxxxxxx> wrote:
> > Hi,all
> >
> > I did a test on kernel3.16 rc6:
> >
> > root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
> > root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
> > root@qemu1:~# ip netns list
> > root@qemu1:~# ip netns add fib1
> > root@qemu1:~# ip netns exec fib1 bash
> > root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding
> > 0
> > root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding
> > 1
> >
> > The behavior of ipv4 and ipv6 is very inconsistent. I checked
> > the kernel source code. I found that from this patch
> > [ipv6: fix bad free of addrconf_init_net], the above difference
> > appeared.
> >
> > Since a net namespace is independent to another. That is, there
> > is no any relationship between the net namespaces. So the behavior
> > of ipv4 is not correct.
> Well, they are already independent, not shared, just that the initial
> value is duplicated from init_net for IPv4.
>
> This change might break existing applications which rely on this
> behavior, but given IPv6 change is almost the same, I think it's ok.
>
> BTW, you need to submit a patch as normal, instead of as an attachment.

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