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net: macvtap driver

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In order to use macvlan with qemu and other tools that require
a tap file descriptor, the macvtap driver adds a small backend
with a character device with the same interface as the tun
driver, with a minimum set of features.

Macvtap interfaces are created in the same way as macvlan
interfaces using ip link, but the netif is just used as a
handle for configuration and accounting, while the data
goes through the chardev. Each macvtap interface has its
own character device, simplifying permission management
significantly over the generic tun/tap driver.

Cc: Patrick McHardy <kaber@trash.net>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: David S. Miller" <davem@davemloft.net>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Or Gerlitz <ogerlitz@voltaire.com>
Cc: netdev@vger.kernel.org
Cc: bridge@lists.linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnd Bergmann 2010-01-30 12:24:26 +00:00 committed by David S. Miller
parent fc0663d6b5
commit 20d29d7a91
4 changed files with 595 additions and 0 deletions
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12
drivers/net/Kconfig
View File

@ -90,6 +90,18 @@ config MACVLAN
To compile this driver as a module, choose M here: the module
will be called macvlan.
config MACVTAP
tristate "MAC-VLAN based tap driver (EXPERIMENTAL)"
depends on MACVLAN
help
This adds a specialized tap character device driver that is based
on the MAC-VLAN network interface, called macvtap. A macvtap device
can be added in the same way as a macvlan device, using 'type
macvlan', and then be accessed through the tap user space interface.
To compile this driver as a module, choose M here: the module
will be called macvtap.
config EQUALIZER
tristate "EQL (serial line load balancing) support"
---help---

1
drivers/net/Makefile
View File

@ -169,6 +169,7 @@ obj-$(CONFIG_XEN_NETDEV_FRONTEND) += xen-netfront.o
obj-$(CONFIG_DUMMY) += dummy.o
obj-$(CONFIG_IFB) += ifb.o
obj-$(CONFIG_MACVLAN) += macvlan.o
obj-$(CONFIG_MACVTAP) += macvtap.o
obj-$(CONFIG_DE600) += de600.o
obj-$(CONFIG_DE620) += de620.o
obj-$(CONFIG_LANCE) += lance.o

581
drivers/net/macvtap.c Normal file
View File

@ -0,0 +1,581 @@
#include <linux/etherdevice.h>
#include <linux/if_macvlan.h>
#include <linux/interrupt.h>
#include <linux/nsproxy.h>
#include <linux/compat.h>
#include <linux/if_tun.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <net/net_namespace.h>
#include <net/rtnetlink.h>
#include <net/sock.h>
/*
* A macvtap queue is the central object of this driver, it connects
* an open character device to a macvlan interface. There can be
* multiple queues on one interface, which map back to queues
* implemented in hardware on the underlying device.
*
* macvtap_proto is used to allocate queues through the sock allocation
* mechanism.
*
* TODO: multiqueue support is currently not implemented, even though
* macvtap is basically prepared for that. We will need to add this
* here as well as in virtio-net and qemu to get line rate on 10gbit
* adapters from a guest.
*/
struct macvtap_queue {
struct sock sk;
struct socket sock;
struct macvlan_dev *vlan;
struct file *file;
};
static struct proto macvtap_proto = {
.name = "macvtap",
.owner = THIS_MODULE,
.obj_size = sizeof (struct macvtap_queue),
};
/*
* Minor number matches netdev->ifindex, so need a potentially
* large value. This also makes it possible to split the
* tap functionality out again in the future by offering it
* from other drivers besides macvtap. As long as every device
* only has one tap, the interface numbers assure that the
* device nodes are unique.
*/
static unsigned int macvtap_major;
#define MACVTAP_NUM_DEVS 65536
static struct class *macvtap_class;
static struct cdev macvtap_cdev;
/*
* RCU usage:
* The macvtap_queue is referenced both from the chardev struct file
* and from the struct macvlan_dev using rcu_read_lock.
*
* We never actually update the contents of a macvtap_queue atomically
* with RCU but it is used for race-free destruction of a queue when
* either the file or the macvlan_dev goes away. Pointers back to
* the dev and the file are implicitly valid as long as the queue
* exists.
*
* The callbacks from macvlan are always done with rcu_read_lock held
* already, while in the file_operations, we get it ourselves.
*
* When destroying a queue, we remove the pointers from the file and
* from the dev and then synchronize_rcu to make sure no thread is
* still using the queue. There may still be references to the struct
* sock inside of the queue from outbound SKBs, but these never
* reference back to the file or the dev. The data structure is freed
* through __sk_free when both our references and any pending SKBs
* are gone.
*
* macvtap_lock is only used to prevent multiple concurrent open()
* calls to assign a new vlan->tap pointer. It could be moved into
* the macvlan_dev itself but is extremely rarely used.
*/
static DEFINE_SPINLOCK(macvtap_lock);
/*
* Choose the next free queue, for now there is only one
*/
static int macvtap_set_queue(struct net_device *dev, struct file *file,
struct macvtap_queue *q)
{
struct macvlan_dev *vlan = netdev_priv(dev);
int err = -EBUSY;
spin_lock(&macvtap_lock);
if (rcu_dereference(vlan->tap))
goto out;
err = 0;
q->vlan = vlan;
rcu_assign_pointer(vlan->tap, q);
q->file = file;
rcu_assign_pointer(file->private_data, q);
out:
spin_unlock(&macvtap_lock);
return err;
}
/*
* We must destroy each queue exactly once, when either
* the netdev or the file go away.
*
* Using the spinlock makes sure that we don't get
* to the queue again after destroying it.
*
* synchronize_rcu serializes with the packet flow
* that uses rcu_read_lock.
*/
static void macvtap_del_queue(struct macvtap_queue **qp)
{
struct macvtap_queue *q;
spin_lock(&macvtap_lock);
q = rcu_dereference(*qp);
if (!q) {
spin_unlock(&macvtap_lock);
return;
}
rcu_assign_pointer(q->vlan->tap, NULL);
rcu_assign_pointer(q->file->private_data, NULL);
spin_unlock(&macvtap_lock);
synchronize_rcu();
sock_put(&q->sk);
}
/*
* Since we only support one queue, just dereference the pointer.
*/
static struct macvtap_queue *macvtap_get_queue(struct net_device *dev,
struct sk_buff *skb)
{
struct macvlan_dev *vlan = netdev_priv(dev);
return rcu_dereference(vlan->tap);
}
static void macvtap_del_queues(struct net_device *dev)
{
struct macvlan_dev *vlan = netdev_priv(dev);
macvtap_del_queue(&vlan->tap);
}
static inline struct macvtap_queue *macvtap_file_get_queue(struct file *file)
{
rcu_read_lock_bh();
return rcu_dereference(file->private_data);
}
static inline void macvtap_file_put_queue(void)
{
rcu_read_unlock_bh();
}
/*
* Forward happens for data that gets sent from one macvlan
* endpoint to another one in bridge mode. We just take
* the skb and put it into the receive queue.
*/
static int macvtap_forward(struct net_device *dev, struct sk_buff *skb)
{
struct macvtap_queue *q = macvtap_get_queue(dev, skb);
if (!q)
return -ENOLINK;
skb_queue_tail(&q->sk.sk_receive_queue, skb);
wake_up(q->sk.sk_sleep);
return 0;
}
/*
* Receive is for data from the external interface (lowerdev),
* in case of macvtap, we can treat that the same way as
* forward, which macvlan cannot.
*/
static int macvtap_receive(struct sk_buff *skb)
{
skb_push(skb, ETH_HLEN);
return macvtap_forward(skb->dev, skb);
}
static int macvtap_newlink(struct net *src_net,
struct net_device *dev,
struct nlattr *tb[],
struct nlattr *data[])
{
struct device *classdev;
dev_t devt;
int err;
err = macvlan_common_newlink(src_net, dev, tb, data,
macvtap_receive, macvtap_forward);
if (err)
goto out;
devt = MKDEV(MAJOR(macvtap_major), dev->ifindex);
classdev = device_create(macvtap_class, &dev->dev, devt,
dev, "tap%d", dev->ifindex);
if (IS_ERR(classdev)) {
err = PTR_ERR(classdev);
macvtap_del_queues(dev);
}
out:
return err;
}
static void macvtap_dellink(struct net_device *dev,
struct list_head *head)
{
device_destroy(macvtap_class,
MKDEV(MAJOR(macvtap_major), dev->ifindex));
macvtap_del_queues(dev);
macvlan_dellink(dev, head);
}
static struct rtnl_link_ops macvtap_link_ops __read_mostly = {
.kind = "macvtap",
.newlink = macvtap_newlink,
.dellink = macvtap_dellink,
};
static void macvtap_sock_write_space(struct sock *sk)
{
if (!sock_writeable(sk) ||
!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags))
return;
if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
wake_up_interruptible_sync(sk->sk_sleep);
}
static int macvtap_open(struct inode *inode, struct file *file)
{
struct net *net = current->nsproxy->net_ns;
struct net_device *dev = dev_get_by_index(net, iminor(inode));
struct macvtap_queue *q;
int err;
err = -ENODEV;
if (!dev)
goto out;
/* check if this is a macvtap device */
err = -EINVAL;
if (dev->rtnl_link_ops != &macvtap_link_ops)
goto out;
err = -ENOMEM;
q = (struct macvtap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
&macvtap_proto);
if (!q)
goto out;
init_waitqueue_head(&q->sock.wait);
q->sock.type = SOCK_RAW;
q->sock.state = SS_CONNECTED;
sock_init_data(&q->sock, &q->sk);
q->sk.sk_allocation = GFP_ATOMIC; /* for now */
q->sk.sk_write_space = macvtap_sock_write_space;
err = macvtap_set_queue(dev, file, q);
if (err)
sock_put(&q->sk);
out:
if (dev)
dev_put(dev);
return err;
}
static int macvtap_release(struct inode *inode, struct file *file)
{
macvtap_del_queue((struct macvtap_queue **)&file->private_data);
return 0;
}
static unsigned int macvtap_poll(struct file *file, poll_table * wait)
{
struct macvtap_queue *q = macvtap_file_get_queue(file);
unsigned int mask = POLLERR;
if (!q)
goto out;
mask = 0;
poll_wait(file, &q->sock.wait, wait);
if (!skb_queue_empty(&q->sk.sk_receive_queue))
mask |= POLLIN | POLLRDNORM;
if (sock_writeable(&q->sk) ||
(!test_and_set_bit(SOCK_ASYNC_NOSPACE, &q->sock.flags) &&
sock_writeable(&q->sk)))
mask |= POLLOUT | POLLWRNORM;
out:
macvtap_file_put_queue();
return mask;
}
/* Get packet from user space buffer */
static ssize_t macvtap_get_user(struct macvtap_queue *q,
const struct iovec *iv, size_t count,
int noblock)
{
struct sk_buff *skb;
size_t len = count;
int err;
if (unlikely(len < ETH_HLEN))
return -EINVAL;
skb = sock_alloc_send_skb(&q->sk, NET_IP_ALIGN + len, noblock, &err);
if (!skb) {
macvlan_count_rx(q->vlan, 0, false, false);
return err;
}
skb_reserve(skb, NET_IP_ALIGN);
skb_put(skb, count);
if (skb_copy_datagram_from_iovec(skb, 0, iv, 0, len)) {
macvlan_count_rx(q->vlan, 0, false, false);
kfree_skb(skb);
return -EFAULT;
}
skb_set_network_header(skb, ETH_HLEN);
macvlan_start_xmit(skb, q->vlan->dev);
return count;
}
static ssize_t macvtap_aio_write(struct kiocb *iocb, const struct iovec *iv,
unsigned long count, loff_t pos)
{
struct file *file = iocb->ki_filp;
ssize_t result = -ENOLINK;
struct macvtap_queue *q = macvtap_file_get_queue(file);
if (!q)
goto out;
result = macvtap_get_user(q, iv, iov_length(iv, count),
file->f_flags & O_NONBLOCK);
out:
macvtap_file_put_queue();
return result;
}
/* Put packet to the user space buffer */
static ssize_t macvtap_put_user(struct macvtap_queue *q,
const struct sk_buff *skb,
const struct iovec *iv, int len)
{
struct macvlan_dev *vlan = q->vlan;
int ret;
len = min_t(int, skb->len, len);
ret = skb_copy_datagram_const_iovec(skb, 0, iv, 0, len);
macvlan_count_rx(vlan, len, ret == 0, 0);
return ret ? ret : len;
}
static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
unsigned long count, loff_t pos)
{
struct file *file = iocb->ki_filp;
struct macvtap_queue *q = macvtap_file_get_queue(file);
DECLARE_WAITQUEUE(wait, current);
struct sk_buff *skb;
ssize_t len, ret = 0;
if (!q) {
ret = -ENOLINK;
goto out;
}
len = iov_length(iv, count);
if (len < 0) {
ret = -EINVAL;
goto out;
}
add_wait_queue(q->sk.sk_sleep, &wait);
while (len) {
current->state = TASK_INTERRUPTIBLE;
/* Read frames from the queue */
skb = skb_dequeue(&q->sk.sk_receive_queue);
if (!skb) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
/* Nothing to read, let's sleep */
schedule();
continue;
}
ret = macvtap_put_user(q, skb, iv, len);
kfree_skb(skb);
break;
}
current->state = TASK_RUNNING;
remove_wait_queue(q->sk.sk_sleep, &wait);
out:
macvtap_file_put_queue();
return ret;
}
/*
* provide compatibility with generic tun/tap interface
*/
static long macvtap_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct macvtap_queue *q;
void __user *argp = (void __user *)arg;
struct ifreq __user *ifr = argp;
unsigned int __user *up = argp;
unsigned int u;
char devname[IFNAMSIZ];
switch (cmd) {
case TUNSETIFF:
/* ignore the name, just look at flags */
if (get_user(u, &ifr->ifr_flags))
return -EFAULT;
if (u != (IFF_TAP | IFF_NO_PI))
return -EINVAL;
return 0;
case TUNGETIFF:
q = macvtap_file_get_queue(file);
if (!q)
return -ENOLINK;
memcpy(devname, q->vlan->dev->name, sizeof(devname));
macvtap_file_put_queue();
if (copy_to_user(&ifr->ifr_name, q->vlan->dev->name, IFNAMSIZ) ||
put_user((TUN_TAP_DEV | TUN_NO_PI), &ifr->ifr_flags))
return -EFAULT;
return 0;
case TUNGETFEATURES:
if (put_user((IFF_TAP | IFF_NO_PI), up))
return -EFAULT;
return 0;
case TUNSETSNDBUF:
if (get_user(u, up))
return -EFAULT;
q = macvtap_file_get_queue(file);
q->sk.sk_sndbuf = u;
macvtap_file_put_queue();
return 0;
case TUNSETOFFLOAD:
/* let the user check for future flags */
if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
TUN_F_TSO_ECN | TUN_F_UFO))
return -EINVAL;
/* TODO: add support for these, so far we don't
support any offload */
if (arg & (TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
TUN_F_TSO_ECN | TUN_F_UFO))
return -EINVAL;
return 0;
default:
return -EINVAL;
}
}
#ifdef CONFIG_COMPAT
static long macvtap_compat_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return macvtap_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
}
#endif
static const struct file_operations macvtap_fops = {
.owner = THIS_MODULE,
.open = macvtap_open,
.release = macvtap_release,
.aio_read = macvtap_aio_read,
.aio_write = macvtap_aio_write,
.poll = macvtap_poll,
.llseek = no_llseek,
.unlocked_ioctl = macvtap_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = macvtap_compat_ioctl,
#endif
};
static int macvtap_init(void)
{
int err;
err = alloc_chrdev_region(&macvtap_major, 0,
MACVTAP_NUM_DEVS, "macvtap");
if (err)
goto out1;
cdev_init(&macvtap_cdev, &macvtap_fops);
err = cdev_add(&macvtap_cdev, macvtap_major, MACVTAP_NUM_DEVS);
if (err)
goto out2;
macvtap_class = class_create(THIS_MODULE, "macvtap");
if (IS_ERR(macvtap_class)) {
err = PTR_ERR(macvtap_class);
goto out3;
}
err = macvlan_link_register(&macvtap_link_ops);
if (err)
goto out4;
return 0;
out4:
class_unregister(macvtap_class);
out3:
cdev_del(&macvtap_cdev);
out2:
unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
out1:
return err;
}
module_init(macvtap_init);
static void macvtap_exit(void)
{
rtnl_link_unregister(&macvtap_link_ops);
class_unregister(macvtap_class);
cdev_del(&macvtap_cdev);
unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
}
module_exit(macvtap_exit);
MODULE_ALIAS_RTNL_LINK("macvtap");
MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
MODULE_LICENSE("GPL");

1
include/linux/if_macvlan.h
View File

@ -34,6 +34,7 @@ struct macvlan_dev {
enum macvlan_mode mode;
int (*receive)(struct sk_buff *skb);
int (*forward)(struct net_device *dev, struct sk_buff *skb);
struct macvtap_queue *tap;
};
static inline void macvlan_count_rx(const struct macvlan_dev *vlan,