[net-next] net: Allow userns root to control tun and tap devices

Allow an unpriviled user who has created a user namespace, and then
created a network namespace to effectively use the new network
namespace, by reducing capable(CAP_NET_ADMIN) calls to
ns_capable(net->user_ns,CAP_NET_ADMIN) calls.

Allow setting of the tun iff flags.
Allow creating of tun devices.
Allow adding a new queue to a tun device.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 drivers/net/tun.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

Quoting Eric W. Biederman (ebiederm@xmission.com):
> 
> Allow an unpriviled user who has created a user namespace, and then
> created a network namespace to effectively use the new network
> namespace, by reducing capable(CAP_NET_ADMIN) calls to
> ns_capable(net->user_ns,CAP_NET_ADMIN) calls.
> 
> Allow setting of the tun iff flags.
> Allow creating of tun devices.
> Allow adding a new queue to a tun device.
> 

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>

> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>  drivers/net/tun.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index b44d7b7..b01e8c0 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -373,10 +373,11 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
>  static inline bool tun_not_capable(struct tun_struct *tun)
>  {
>  	const struct cred *cred = current_cred();
> +	struct net *net = dev_net(tun->dev);
>  
>  	return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
>  		  (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
> -		!capable(CAP_NET_ADMIN);
> +		!ns_capable(net->user_ns, CAP_NET_ADMIN);
>  }
>  
>  static void tun_set_real_num_queues(struct tun_struct *tun)
> @@ -1559,7 +1560,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>  		char *name;
>  		unsigned long flags = 0;
>  
> -		if (!capable(CAP_NET_ADMIN))
> +		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
>  			return -EPERM;
>  		err = security_tun_dev_create();
>  		if (err < 0)
> -- 
> 1.7.5.4
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From: "Serge E. Hallyn" <serge@hallyn.com>
Date: Mon, 19 Nov 2012 14:23:31 +0000

> Quoting Eric W. Biederman (ebiederm@xmission.com):
>> 
>> Allow an unpriviled user who has created a user namespace, and then
>> created a network namespace to effectively use the new network
>> namespace, by reducing capable(CAP_NET_ADMIN) calls to
>> ns_capable(net->user_ns,CAP_NET_ADMIN) calls.
>> 
>> Allow setting of the tun iff flags.
>> Allow creating of tun devices.
>> Allow adding a new queue to a tun device.
>> 
> 
> Acked-by: Serge Hallyn <serge.hallyn@canonical.com>

Applied.
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