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[PATCH] tun: don't hold network namespace by tun sockets [message #45476] Mon, 12 March 2012 13:49 Go to next message
Stanislav Kinsbursky is currently offline  Stanislav Kinsbursky
Messages: 683
Registered: October 2011
Senior Member
From: *parallels.com
v3: added previously removed sock_put() to the tun_release() callback, because
sk_release_kernel() doesn't drop the socket reference.

v2: sk_release_kernel() used for socket release. Dummy tun_release() is
required for sk_release_kernel() ---> sock_release() ---> sock->ops->release()
call.

TUN was designed to destroy it's socket on network namesapce shutdown. But this
will never happen for persistent device, because it's socket holds network
namespace.
This patch removes of holding network namespace by TUN socket and replaces it
by creating socket in init_net and then changing it's net it to desired one. On
shutdown socket is moved back to init_net prior to final put.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>

---
drivers/net/tun.c | 15 ++++++++++++---
1 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2c5d349..74d7f76 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -359,7 +359,7 @@ static void tun_free_netdev(struct net_device *dev)
{
struct tun_struct *tun = netdev_priv(dev);

- sock_put(tun->socket.sk);
+ sk_release_kernel(tun->socket.sk);
}

/* Net device open. */
@@ -980,10 +980,18 @@ static int tun_recvmsg(struct kiocb *iocb, struct socket *sock,
return ret;
}

+static int tun_release(struct socket *sock)
+{
+ if (sock->sk)
+ sock_put(sock->sk);
+ return 0;
+}
+
/* Ops structure to mimic raw sockets with tun */
static const struct proto_ops tun_socket_ops = {
.sendmsg = tun_sendmsg,
.recvmsg = tun_recvmsg,
+ .release = tun_release,
};

static struct proto tun_proto = {
@@ -1110,10 +1118,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr);

err = -ENOMEM;
- sk = sk_alloc(net, AF_UNSPEC, GFP_KERNEL, &tun_proto);
+ sk = sk_alloc(&init_net, AF_UNSPEC, GFP_KERNEL, &tun_proto);
if (!sk)
goto err_free_dev;

+ sk_change_net(sk, net);
tun->socket.wq = &tun->wq;
init_waitqueue_head(&tun->wq.wait);
tun->socket.ops = &tun_socket_ops;
@@ -1174,7 +1183,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
return 0;

err_free_sk:
- sock_put(sk);
+ tun_free_netdev(dev);
err_free_dev:
free_netdev(dev);
failed:
Re: [PATCH] tun: don't hold network namespace by tun sockets [message #45477 is a reply to message #45476] Mon, 12 March 2012 14:28 Go to previous message
Stanislav Kinsbursky is currently offline  Stanislav Kinsbursky
Messages: 683
Registered: October 2011
Senior Member
From: *parallels.com
Drop this. Sorry for inconvenience - mail server problems.

--
Best regards,
Stanislav Kinsbursky
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