diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2009-01-20 12:02:28 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-01-22 01:00:45 +0100 |
| commit | 38231b7a8d1b74c920822640d1ce8eb8046377fb (patch) | |
| tree | fc7f1c3cc8ef34a64a740a2938934dbd598f0d93 /drivers/net/tun.c | |
| parent | tun: Grab the netns in open. (diff) | |
| download | linux-38231b7a8d1b74c920822640d1ce8eb8046377fb.tar.xz linux-38231b7a8d1b74c920822640d1ce8eb8046377fb.zip | |
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>
Diffstat (limited to 'drivers/net/tun.c')
| -rw-r--r-- | drivers/net/tun.c | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index dfbf58659771..fa93160bf522 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -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); |