netdev - Re: [PATCH] net: vxlan: disallow removing to other namespace

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Date:   Tue, 21 May 2019 19:08:10 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     David Miller <davem@...emloft.net>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH] net: vxlan: disallow removing to other namespace

On Tue, May 21, 2019 at 5:28 PM Nicolas Dichtel
<nicolas.dichtel@...nd.com> wrote:
>
> Le 21/05/2019 à 07:53, Tonghao Zhang a écrit :
> [snip]
> > The problem is that we create one vxlan netdevice(e.g dstport 4789 and
> > external), and move it to
> > one net-namespace, and then we hope create one again(dstport 4789 and
> > external) and move it to other net-namespace, but we can't create it.
> >
> > $ ip netns add ns100
> > $ ip link add vxlan100 type vxlan dstport 4789 external
> > $ ip link set dev vxlan100 netns ns100
> > $ ip link add vxlan200 type vxlan dstport 4789 external
> > RTNETLINK answers: File exists
> Why is this a problem? This error is correct, the interface already exists.
>
> >
> > The better way is that we should create directly it in the
> > net-namespace. To avoid confuse user, disallow moving it to other
> > net-namespace.
> There is no confusion, this is a feature. This link part of the vxlan is in
> another namespace:
>
> $ ip -d -n ns100 link ls vxlan100
> 15: vxlan100: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN mode DEFAULT
> group default qlen 1000
>     link/ether d6:54:ea:b4:46:a5 brd ff:ff:ff:ff:ff:ff link-netnsid 0
> promiscuity 0 minmtu 68 maxmtu 65535
>     vxlan externaladdrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size
> 65536 gso_max_segs 65535
>
> => "link-netnsid 0" means that the link part is in the nsid 0, ie init_net in my
> case.
I got it, thanks
>
> Regards,
> Nicolas