netdev - Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier

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Date:   Sun, 4 Feb 2018 13:11:02 +0100
From:   Christian Brauner <christian.brauner@...onical.com>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     Christian Brauner <christian.brauner@...ntu.com>,
        netdev@...r.kernel.org, ebiederm@...ssion.com, jbenc@...hat.com,
        nicolas.dichtel@...nd.com, linux-kernel@...r.kernel.org,
        dsahern@...il.com, davem@...emloft.net
Subject: Re: [PATCH net 1/1 v1] rtnetlink: require unique netns identifier

On Sat, Feb 03, 2018 at 11:17:01AM -0800, Stephen Hemminger wrote:
> On Sat,  3 Feb 2018 14:29:04 +0100
> Christian Brauner <christian.brauner@...ntu.com> wrote:
> 
> > +static int rtnl_ensure_unique_netns_attr(const struct sock *sk,
> > +					 struct nlattr *tb[],
> > +					 struct netlink_ext_ack *extack)
> > +{
> > +	int ret = -EINVAL;
> > +	struct net *net = NULL, *unique_net = NULL;
> > +
> > +	/* Requests without network namespace ids have been able to specify
> > +	 * multiple properties referring to different network namespaces so
> > +	 * don't regress them.
> > +	 */
> > +	if (!tb[IFLA_IF_NETNSID])
> > +		return 0;
> > +
> > +	if (!tb[IFLA_NET_NS_PID] && !tb[IFLA_NET_NS_FD])
> > +		return 0;
> 
> Isn't this an error?

My reasoning was that having no explicit network namespace identifying
attributes the caller operates on the current network namespace which is
uniquely identified.

> 
> > +
> > +	unique_net = get_net_ns_by_id(sock_net(sk), nla_get_s32(tb[IFLA_IF_NETNSID]));
> > +	if (!unique_net)
> > +		return -1;
> 
> Other paths are returning errno, so why -1 here?

Yes, this should be -EINVAL as well.

Thanks!
Christian