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tun: Make tun_net_xmit atomic wrt tun_attach && tun_detach 

Currently this small race allows for a packet to be received when we
detach from an tun device and still be enqueued.  Not especially
important but not what the code is trying to do.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric W. Biederman 2009-01-20 11:02:28 +00:00 committed by David S. Miller
parent 36b50bab53
commit 38231b7a8d
1 changed files with 17 additions and 7 deletions
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24
drivers/net/tun.c
View File

@ -115,25 +115,33 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
{
struct tun_file *tfile = file->private_data;
const struct cred *cred = current_cred();
int err;
ASSERT_RTNL();
if (tfile->tun)
return -EINVAL;
if (tun->tfile)
return -EBUSY;
/* Check permissions */
if (((tun->owner != -1 && cred->euid != tun->owner) ||
(tun->group != -1 && cred->egid != tun->group)) &&
!capable(CAP_NET_ADMIN))
return -EPERM;
netif_tx_lock_bh(tun->dev);
err = -EINVAL;
if (tfile->tun)
goto out;
err = -EBUSY;
if (tun->tfile)
goto out;
err = 0;
tfile->tun = tun;
tun->tfile = tfile;
return 0;
out:
netif_tx_unlock_bh(tun->dev);
return err;
}
static void __tun_detach(struct tun_struct *tun)
@ -141,8 +149,10 @@ static void __tun_detach(struct tun_struct *tun)
struct tun_file *tfile = tun->tfile;
/* Detach from net device */
netif_tx_lock_bh(tun->dev);
tfile->tun = NULL;
tun->tfile = NULL;
netif_tx_unlock_bh(tun->dev);
/* Drop read queue */
skb_queue_purge(&tun->readq);