* [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached
@ 2013-01-11 8:50 Jason Wang
2013-01-11 8:50 ` [PATCH 2/2] tuntap: fix leaking reference count Jason Wang
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Jason Wang @ 2013-01-11 8:50 UTC (permalink / raw)
To: davem, mst, netdev, linux-kernel; +Cc: Jason Wang, Stefan Hajnoczi
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>
---
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 99b58d8..9a46d70 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -491,8 +491,6 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
err = -EINVAL;
if (rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held()))
goto out;
- if (tfile->detached && tun != tfile->detached)
- goto out;
err = -EBUSY;
if (!(tun->flags & TUN_TAP_MQ) && tun->numqueues == 1)
@@ -1546,6 +1544,9 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
struct net_device *dev;
int err;
+ if (rcu_dereference_protected(tfile->detached, lockdep_rtnl_is_held()))
+ return -EINVAL;
+
dev = __dev_get_by_name(net, ifr->ifr_name);
if (dev) {
if (ifr->ifr_flags & IFF_TUN_EXCL)
--
1.7.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/2] tuntap: fix leaking reference count
2013-01-11 8:50 [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Jason Wang
@ 2013-01-11 8:50 ` Jason Wang
2013-01-11 14:42 ` [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Stefan Hajnoczi
2013-01-11 14:55 ` Eric Dumazet
2 siblings, 0 replies; 6+ messages in thread
From: Jason Wang @ 2013-01-11 8:50 UTC (permalink / raw)
To: davem, mst, netdev, linux-kernel; +Cc: Jason Wang
Reference count leaking of both module and sock were found:
- When a detached file were closed, its sock refcnt from device were not
released, solving this by add the sock_put().
- The module were hold or drop unconditionally in TUNSETPERSIST, which means we
if we set the persist flag for N times, we need unset it for another N
times. Solving this by only hold or drop an reference when there's a flag
change and also drop the reference count when the persist device is deleted.
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/net/tun.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 9a46d70..d690dc8 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -429,8 +429,10 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
/* Drop read queue */
skb_queue_purge(&tfile->sk.sk_receive_queue);
tun_set_real_num_queues(tun);
- } else if (tfile->detached && clean)
+ } else if (tfile->detached && clean) {
tun = tun_enable_queue(tfile);
+ sock_put(&tfile->sk);
+ }
if (clean) {
if (tun && tun->numqueues == 0 && tun->numdisabled == 0 &&
@@ -481,6 +483,9 @@ static void tun_detach_all(struct net_device *dev)
sock_put(&tfile->sk);
}
BUG_ON(tun->numdisabled != 0);
+
+ if (tun->flags & TUN_PERSIST)
+ module_put(THIS_MODULE);
}
static int tun_attach(struct tun_struct *tun, struct file *file)
@@ -1881,10 +1886,11 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
/* Disable/Enable persist mode. Keep an extra reference to the
* module to prevent the module being unprobed.
*/
- if (arg) {
+ if (arg && !(tun->flags & TUN_PERSIST)) {
tun->flags |= TUN_PERSIST;
__module_get(THIS_MODULE);
- } else {
+ }
+ if (!arg && (tun->flags & TUN_PERSIST)) {
tun->flags &= ~TUN_PERSIST;
module_put(THIS_MODULE);
}
--
1.7.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached
2013-01-11 8:50 [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Jason Wang
2013-01-11 8:50 ` [PATCH 2/2] tuntap: fix leaking reference count Jason Wang
@ 2013-01-11 14:42 ` Stefan Hajnoczi
2013-01-12 2:31 ` Jason Wang
2013-01-11 14:55 ` Eric Dumazet
2 siblings, 1 reply; 6+ messages in thread
From: Stefan Hajnoczi @ 2013-01-11 14:42 UTC (permalink / raw)
To: Jason Wang; +Cc: davem, mst, netdev, linux-kernel
On Fri, Jan 11, 2013 at 04:50:41PM +0800, Jason Wang wrote:
> @@ -1546,6 +1544,9 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
> struct net_device *dev;
> int err;
>
> + if (rcu_dereference_protected(tfile->detached, lockdep_rtnl_is_held()))
> + return -EINVAL;
> +
How come none of the other tfile->detached users call rcu_*()?
Stefan
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached
2013-01-11 14:42 ` [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Stefan Hajnoczi
@ 2013-01-12 2:31 ` Jason Wang
0 siblings, 0 replies; 6+ messages in thread
From: Jason Wang @ 2013-01-12 2:31 UTC (permalink / raw)
To: Stefan Hajnoczi; +Cc: davem, mst, netdev, linux-kernel
On 01/11/2013 10:42 PM, Stefan Hajnoczi wrote:
> On Fri, Jan 11, 2013 at 04:50:41PM +0800, Jason Wang wrote:
>> @@ -1546,6 +1544,9 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
>> struct net_device *dev;
>> int err;
>>
>> + if (rcu_dereference_protected(tfile->detached, lockdep_rtnl_is_held()))
>> + return -EINVAL;
>> +
> How come none of the other tfile->detached users call rcu_*()?
Right, no need to use rcu, the access were protected by rtnl lock.
Will repost.
> Stefan
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached
2013-01-11 8:50 [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Jason Wang
2013-01-11 8:50 ` [PATCH 2/2] tuntap: fix leaking reference count Jason Wang
2013-01-11 14:42 ` [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Stefan Hajnoczi
@ 2013-01-11 14:55 ` Eric Dumazet
2013-01-12 2:31 ` Jason Wang
2 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2013-01-11 14:55 UTC (permalink / raw)
To: Jason Wang; +Cc: davem, mst, netdev, linux-kernel, Stefan Hajnoczi
On Fri, 2013-01-11 at 16:50 +0800, Jason Wang wrote:
>
> + if (rcu_dereference_protected(tfile->detached, lockdep_rtnl_is_held()))
> + return -EINVAL;
> +
Thats an open coded rtnl_dereference()
(please cleanup the whole tun.c file)
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-01-12 2:31 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2013-01-11 8:50 [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Jason Wang
2013-01-11 8:50 ` [PATCH 2/2] tuntap: fix leaking reference count Jason Wang
2013-01-11 14:42 ` [PATCH 1/2] tuntap: forbid calling TUNSETIFF when detached Stefan Hajnoczi
2013-01-12 2:31 ` Jason Wang
2013-01-11 14:55 ` Eric Dumazet
2013-01-12 2:31 ` Jason Wang
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