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

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Message-ID: <87a9uekpvw.fsf@xmission.com>
Date:	Sun, 18 Nov 2012 23:34:11 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	David Miller <davem@...emloft.net>
Cc:	<netdev@...r.kernel.org>, "Serge E. Hallyn" <serge@...lyn.com>,
	Linux Containers <containers@...ts.linux-foundation.org>
Subject: [PATCH 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@...ssion.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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