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tuntap: forbid calling TUNSETIFF when detached

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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>
This commit is contained in:
Jason Wang 2013-01-11 16:59:33 +00:00 committed by David S. Miller
parent b8deabd3ee
commit 7c0c3b1a8a
1 changed files with 3 additions and 2 deletions
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5
drivers/net/tun.c
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@ -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)