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* [PATCH V2 0/3] some fixes of tuntap
@ 2013-01-12  2:59 Jason Wang
  2013-01-12  2:59 ` [PATCH V2 1/3] tuntap: switch to use rtnl_dereference() Jason Wang
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Jason Wang @ 2013-01-12  2:59 UTC (permalink / raw)
  To: davem, mst, netdev, linux-kernel; +Cc: edumazet, stefanha, Jason Wang

Hi all:

There series fixes two issues:
- Don't allow calling TUNSETIFF when a file is detached which may cause kernel
data structure corrupt.
- Fix the reference count leaking of sock and module.

Plus a suggestion from Eric to use rtnl_dereference() instead of the open code.

Changes from v1:
- don't use rcu to dereference tfile->detached as it was already protected by
rtnl lock.
- add a patch of switching to use rtnl_dereference().

Jason Wang (3):
  tuntap: switch to use rtnl_dereference()
  tuntap: forbid calling TUNSETIFF when detached
  tuntap: fix leaking reference count

 drivers/net/tun.c |   44 ++++++++++++++++++++++----------------------
 1 files changed, 22 insertions(+), 22 deletions(-)


^ permalink raw reply	[flat|nested] 5+ messages in thread
* [PATCH V2 1/3] tuntap: switch to use rtnl_dereference()
  2013-01-12  2:59 [PATCH V2 0/3] some fixes of tuntap Jason Wang
@ 2013-01-12  2:59 ` Jason Wang
  2013-01-12  2:59 ` [PATCH V2 2/3] tuntap: forbid calling TUNSETIFF when detached Jason Wang
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2013-01-12  2:59 UTC (permalink / raw)
  To: davem, mst, netdev, linux-kernel; +Cc: edumazet, stefanha, Jason Wang

Switch to use rtnl_dereference() instead of the open code, suggested by Eric.

Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c |   27 ++++++++++-----------------
 1 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 99b58d8..aa963c4 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -404,8 +404,8 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 	struct tun_struct *tun;
 	struct net_device *dev;
 
-	tun = rcu_dereference_protected(tfile->tun,
-					lockdep_rtnl_is_held());
+	tun = rtnl_dereference(tfile->tun);
+
 	if (tun) {
 		u16 index = tfile->queue_index;
 		BUG_ON(index >= tun->numqueues);
@@ -414,8 +414,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 		rcu_assign_pointer(tun->tfiles[index],
 				   tun->tfiles[tun->numqueues - 1]);
 		rcu_assign_pointer(tfile->tun, NULL);
-		ntfile = rcu_dereference_protected(tun->tfiles[index],
-						   lockdep_rtnl_is_held());
+		ntfile = rtnl_dereference(tun->tfiles[index]);
 		ntfile->queue_index = index;
 
 		--tun->numqueues;
@@ -458,8 +457,7 @@ static void tun_detach_all(struct net_device *dev)
 	int i, n = tun->numqueues;
 
 	for (i = 0; i < n; i++) {
-		tfile = rcu_dereference_protected(tun->tfiles[i],
-						  lockdep_rtnl_is_held());
+		tfile = rtnl_dereference(tun->tfiles[i]);
 		BUG_ON(!tfile);
 		wake_up_all(&tfile->wq.wait);
 		rcu_assign_pointer(tfile->tun, NULL);
@@ -469,8 +467,7 @@ static void tun_detach_all(struct net_device *dev)
 
 	synchronize_net();
 	for (i = 0; i < n; i++) {
-		tfile = rcu_dereference_protected(tun->tfiles[i],
-						  lockdep_rtnl_is_held());
+		tfile = rtnl_dereference(tun->tfiles[i]);
 		/* Drop read queue */
 		skb_queue_purge(&tfile->sk.sk_receive_queue);
 		sock_put(&tfile->sk);
@@ -489,7 +486,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
 	int err;
 
 	err = -EINVAL;
-	if (rcu_dereference_protected(tfile->tun, lockdep_rtnl_is_held()))
+	if (rtnl_dereference(tfile->tun))
 		goto out;
 	if (tfile->detached && tun != tfile->detached)
 		goto out;
@@ -1740,8 +1737,7 @@ static void tun_detach_filter(struct tun_struct *tun, int n)
 	struct tun_file *tfile;
 
 	for (i = 0; i < n; i++) {
-		tfile = rcu_dereference_protected(tun->tfiles[i],
-						  lockdep_rtnl_is_held());
+		tfile = rtnl_dereference(tun->tfiles[i]);
 		sk_detach_filter(tfile->socket.sk);
 	}
 
@@ -1754,8 +1750,7 @@ static int tun_attach_filter(struct tun_struct *tun)
 	struct tun_file *tfile;
 
 	for (i = 0; i < tun->numqueues; i++) {
-		tfile = rcu_dereference_protected(tun->tfiles[i],
-						  lockdep_rtnl_is_held());
+		tfile = rtnl_dereference(tun->tfiles[i]);
 		ret = sk_attach_filter(&tun->fprog, tfile->socket.sk);
 		if (ret) {
 			tun_detach_filter(tun, i);
@@ -1773,8 +1768,7 @@ static void tun_set_sndbuf(struct tun_struct *tun)
 	int i;
 
 	for (i = 0; i < tun->numqueues; i++) {
-		tfile = rcu_dereference_protected(tun->tfiles[i],
-						lockdep_rtnl_is_held());
+		tfile = rtnl_dereference(tun->tfiles[i]);
 		tfile->socket.sk->sk_sndbuf = tun->sndbuf;
 	}
 }
@@ -1794,8 +1788,7 @@ static int tun_set_queue(struct file *file, struct ifreq *ifr)
 		else
 			ret = tun_attach(tun, file);
 	} else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
-		tun = rcu_dereference_protected(tfile->tun,
-						lockdep_rtnl_is_held());
+		tun = rtnl_dereference(tfile->tun);
 		if (!tun || !(tun->flags & TUN_TAP_MQ))
 			ret = -EINVAL;
 		else
-- 
1.7.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* [PATCH V2 2/3] tuntap: forbid calling TUNSETIFF when detached
  2013-01-12  2:59 [PATCH V2 0/3] some fixes of tuntap Jason Wang
  2013-01-12  2:59 ` [PATCH V2 1/3] tuntap: switch to use rtnl_dereference() Jason Wang
@ 2013-01-12  2:59 ` Jason Wang
  2013-01-12  2:59 ` [PATCH V2 3/3] tuntap: fix leaking reference count Jason Wang
  2013-01-12  3:42 ` [PATCH V2 0/3] some fixes of tuntap David Miller
  3 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2013-01-12  2:59 UTC (permalink / raw)
  To: davem, mst, netdev, linux-kernel; +Cc: edumazet, stefanha, Jason Wang

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 aa963c4..a36b56f 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -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)
-- 
1.7.1


^ permalink raw reply related	[flat|nested] 5+ messages in thread
* [PATCH V2 3/3] tuntap: fix leaking reference count
  2013-01-12  2:59 [PATCH V2 0/3] some fixes of tuntap Jason Wang
  2013-01-12  2:59 ` [PATCH V2 1/3] tuntap: switch to use rtnl_dereference() Jason Wang
  2013-01-12  2:59 ` [PATCH V2 2/3] tuntap: forbid calling TUNSETIFF when detached Jason Wang
@ 2013-01-12  2:59 ` Jason Wang
  2013-01-12  3:42 ` [PATCH V2 0/3] some fixes of tuntap David Miller
  3 siblings, 0 replies; 5+ messages in thread
From: Jason Wang @ 2013-01-12  2:59 UTC (permalink / raw)
  To: davem, mst, netdev, linux-kernel; +Cc: edumazet, stefanha, 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 a36b56f..af372d0 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -428,8 +428,10 @@ 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 &&
@@ -478,6 +480,9 @@ 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)
@@ -1874,10 +1879,11 @@ 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] 5+ messages in thread
* Re: [PATCH V2 0/3] some fixes of tuntap
  2013-01-12  2:59 [PATCH V2 0/3] some fixes of tuntap Jason Wang
                   ` (2 preceding siblings ...)
  2013-01-12  2:59 ` [PATCH V2 3/3] tuntap: fix leaking reference count Jason Wang
@ 2013-01-12  3:42 ` David Miller
  3 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2013-01-12  3:42 UTC (permalink / raw)
  To: jasowang; +Cc: mst, netdev, linux-kernel, edumazet, stefanha

From: Jason Wang <jasowang@redhat.com>
Date: Sat, 12 Jan 2013 10:59:31 +0800

> There series fixes two issues:
> - Don't allow calling TUNSETIFF when a file is detached which may cause kernel
> data structure corrupt.
> - Fix the reference count leaking of sock and module.
> 
> Plus a suggestion from Eric to use rtnl_dereference() instead of the open code.
> 
> Changes from v1:
> - don't use rcu to dereference tfile->detached as it was already protected by
> rtnl lock.
> - add a patch of switching to use rtnl_dereference().

All applied, thanks Jason.

^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2013-01-12  3:42 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-01-12  2:59 [PATCH V2 0/3] some fixes of tuntap Jason Wang
2013-01-12  2:59 ` [PATCH V2 1/3] tuntap: switch to use rtnl_dereference() Jason Wang
2013-01-12  2:59 ` [PATCH V2 2/3] tuntap: forbid calling TUNSETIFF when detached Jason Wang
2013-01-12  2:59 ` [PATCH V2 3/3] tuntap: fix leaking reference count Jason Wang
2013-01-12  3:42 ` [PATCH V2 0/3] some fixes of tuntap David Miller

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