Commit 7c0c3b1a authored Jan 11, 2013 by Jason Wang Committed by David S. Miller Jan 11, 2013

tuntap: forbid calling TUNSETIFF when detached

Michael points out that even after Stefan's fix the TUNSETIFF is still allowed
to create a new tap device. This because we only check tfile->tun but the
tfile->detached were introduced. Fix this by failing early in tun_set_iff() if
the file is detached. After this fix, there's no need to do the check again in
tun_set_iff(), so this patch removes it.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b8deabd3

drivers/net/tun.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -488,8 +488,6 @@ static int tun_attach(struct tun_struct tun, struct file file)
		err = -EINVAL;
		if (rtnl_dereference(tfile->tun))
		goto out;
		if (tfile->detached && tun != tfile->detached)
		goto out;

		err = -EBUSY;
		if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)
		@@ -1543,6 +1541,9 @@ static int tun_set_iff(struct net net, struct file file, struct ifreq *ifr)
		struct net_device *dev;
		int err;

		if (tfile->detached)
		return -EINVAL;

		dev = __dev_get_by_name(net, ifr->ifr_name);
		if (dev) {
		if (ifr->ifr_flags & IFF_TUN_EXCL)