netdev - Re: [PATCH net] rtnetlink: always put ILFA_LINK for links with a link-netnsid

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Date:   Mon, 13 May 2019 15:42:06 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     Nicolas Dichtel <nicolas.dichtel@...nd.com>
Cc:     netdev@...r.kernel.org, Dan Winship <danw@...hat.com>
Subject: Re: [PATCH net] rtnetlink: always put ILFA_LINK for links with a
 link-netnsid

2019-05-13, 15:17:33 +0200, Nicolas Dichtel wrote:
> Le 13/05/2019 à 15:01, Sabrina Dubroca a écrit :
> > Currently, nla_put_iflink() doesn't put the IFLA_LINK attribute when
> > iflink == ifindex.
> > 
> > In some cases, a device can be created in a different netns with the
> > same ifindex as its parent. That device will not dump its IFLA_LINK
> > attribute, which can confuse some userspace software that expects it.
> > For example, if the last ifindex created in init_net and foo are both
> > 8, these commands will trigger the issue:
> > 
> >     ip link add parent type dummy                   # ifindex 9
> >     ip link add link parent netns foo type macvlan  # ifindex 9 in ns foo
> > 
> > So, in case a device puts the IFLA_LINK_NETNSID attribute in a dump,
> > always put the IFLA_LINK attribute as well.
> > 
> > Thanks to Dan Winship for analyzing the original OpenShift bug down to
> > the missing netlink attribute.
> Good catch.
> 
> > 
> > Analyzed-by: Dan Winship <danw@...hat.com>
> > Fixes: a54acb3a6f85 ("dev: introduce dev_get_iflink()")
> I don't agree with the Fixes tag. The test 'iflink != ifindex' is here at least
> since the beginning of the git history.

Hmpf, right, now that I re-blamed, I see. I don't know why I stopped
on your patch, sorry.

> > Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
> Acked-by: Nicolas Dichtel <nicolas.dichtel@...nd.com>

Thanks!

I'll repost with a correct Fixes tag and your Ack.

-- 
Sabrina