netdev - Re: [PATCH net-next v4 1/4] netns: add genl cmd to add and get peer netns ids

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Date:	Fri, 31 Oct 2014 10:41:24 +0100
From:	Nicolas Dichtel <nicolas.dichtel@...nd.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	netdev@...r.kernel.org, containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
	davem@...emloft.net, stephen@...workplumber.org,
	akpm@...ux-foundation.org, luto@...capital.net,
	cwang@...pensource.com
Subject: Re: [PATCH net-next v4 1/4] netns: add genl cmd to add and get peer
 netns ids

Le 30/10/2014 19:35, Eric W. Biederman a écrit :
> Nicolas Dichtel <nicolas.dichtel@...nd.com> writes:
>
>> With this patch, a user can define an id for a peer netns by providing a FD or a
>> PID. These ids are local to netns (ie valid only into one netns).
>
> Scratches head.  Do you actually find value in using the pid instead of
> a file descriptor?
I copied the mechanism from rtnl_link_get_net():
First check if the user provides a PID, if not, check for a FD.

>
> Doing things by pid was an early attempt to make things work, and has
> been a bit clutsy.  If you don't find value in it I would recommend just
> supporting getting/setting the network namespace by file descriptor.
Hmm, if I understand well, it's what is done in the patch:

[snip]
>> +static int netns_nl_cmd_newid(struct sk_buff *skb, struct genl_info *info)
>> +{
[snip]
>> +	if (info->attrs[NETNSA_PID])
>> +		peer = get_net_ns_by_pid(nla_get_u32(info->attrs[NETNSA_PID]));
>> +	else if (info->attrs[NETNSA_FD])
>> +		peer = get_net_ns_by_fd(nla_get_u32(info->attrs[NETNSA_FD]));
>> +	else
>> +		return -EINVAL;
>> +	if (IS_ERR(peer))
>> +		return PTR_ERR(peer);

Am I right?


Regards,
Nicolas
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