linux/drivers/net/macvtap.c
Marc Angel 17af2bce88 macvtap: add namespace support to the sysfs device class
When creating macvtaps that are expected to have the same ifindex
in different network namespaces, only the first one will succeed.
The others will fail with a sysfs_warn_dup warning due to them trying
to create the following sysfs link (with 'NN' the ifindex of macvtapX):

/sys/class/macvtap/tapNN -> /sys/devices/virtual/net/macvtapX/tapNN

This is reproducible by running the following commands:

ip netns add ns1
ip netns add ns2
ip link add veth0 type veth peer name veth1
ip link set veth0 netns ns1
ip link set veth1 netns ns2
ip netns exec ns1 ip l add link veth0 macvtap0 type macvtap
ip netns exec ns2 ip l add link veth1 macvtap1 type macvtap

The last command will fail with "RTNETLINK answers: File exists" (along
with the kernel warning) but retrying it will work because the ifindex
was incremented.

The 'net' device class is isolated between network namespaces so each
one has its own hierarchy of net devices.
This isn't the case for the 'macvtap' device class.
The problem occurs half-way through the netdev registration, when
`macvtap_device_event` is called-back to create the 'tapNN' macvtap
class device under the 'macvtapX' net class device.

This patch adds namespace support to the 'macvtap' device class so
that /sys/class/macvtap is no longer shared between net namespaces.

However, making the macvtap sysfs class namespace-aware has the side
effect of changing /sys/devices/virtual/net/macvtapX/tapNN  into
/sys/devices/virtual/net/macvtapX/macvtap/tapNN.

This is due to Commit 24b1442 ("Driver-core: Always create class
directories for classses that support namespaces") and the fact that
class devices supporting namespaces are really not supposed to be placed
directly under other class devices.

To avoid breaking userland, a tapNN symlink pointing to macvtap/tapNN is
created inside the macvtapX directory.

Signed-off-by: Marc Angel <marc@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-05-06 18:25:09 -04:00

1395 lines
33 KiB
C

#include <linux/etherdevice.h>
#include <linux/if_macvlan.h>
#include <linux/if_vlan.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/slab.h>
#include <linux/wait.h>
#include <linux/cdev.h>
#include <linux/idr.h>
#include <linux/fs.h>
#include <linux/uio.h>
#include <net/net_namespace.h>
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <linux/virtio_net.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.
*
*/
struct macvtap_queue {
struct sock sk;
struct socket sock;
struct socket_wq wq;
int vnet_hdr_sz;
struct macvlan_dev __rcu *vlan;
struct file *file;
unsigned int flags;
u16 queue_index;
bool enabled;
struct list_head next;
};
#define MACVTAP_FEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
#define MACVTAP_VNET_LE 0x80000000
#define MACVTAP_VNET_BE 0x40000000
#ifdef CONFIG_TUN_VNET_CROSS_LE
static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)
{
return q->flags & MACVTAP_VNET_BE ? false :
virtio_legacy_is_little_endian();
}
static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *sp)
{
int s = !!(q->flags & MACVTAP_VNET_BE);
if (put_user(s, sp))
return -EFAULT;
return 0;
}
static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *sp)
{
int s;
if (get_user(s, sp))
return -EFAULT;
if (s)
q->flags |= MACVTAP_VNET_BE;
else
q->flags &= ~MACVTAP_VNET_BE;
return 0;
}
#else
static inline bool macvtap_legacy_is_little_endian(struct macvtap_queue *q)
{
return virtio_legacy_is_little_endian();
}
static long macvtap_get_vnet_be(struct macvtap_queue *q, int __user *argp)
{
return -EINVAL;
}
static long macvtap_set_vnet_be(struct macvtap_queue *q, int __user *argp)
{
return -EINVAL;
}
#endif /* CONFIG_TUN_VNET_CROSS_LE */
static inline bool macvtap_is_little_endian(struct macvtap_queue *q)
{
return q->flags & MACVTAP_VNET_LE ||
macvtap_legacy_is_little_endian(q);
}
static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)
{
return __virtio16_to_cpu(macvtap_is_little_endian(q), val);
}
static inline __virtio16 cpu_to_macvtap16(struct macvtap_queue *q, u16 val)
{
return __cpu_to_virtio16(macvtap_is_little_endian(q), val);
}
static struct proto macvtap_proto = {
.name = "macvtap",
.owner = THIS_MODULE,
.obj_size = sizeof (struct macvtap_queue),
};
/*
* Variables for dealing with macvtaps device numbers.
*/
static dev_t macvtap_major;
#define MACVTAP_NUM_DEVS (1U << MINORBITS)
static DEFINE_MUTEX(minor_lock);
static DEFINE_IDR(minor_idr);
#define GOODCOPY_LEN 128
static const void *macvtap_net_namespace(struct device *d)
{
struct net_device *dev = to_net_dev(d->parent);
return dev_net(dev);
}
static struct class macvtap_class = {
.name = "macvtap",
.owner = THIS_MODULE,
.ns_type = &net_ns_type_operations,
.namespace = macvtap_net_namespace,
};
static struct cdev macvtap_cdev;
static const struct proto_ops macvtap_socket_ops;
#define TUN_OFFLOADS (NETIF_F_HW_CSUM | NETIF_F_TSO_ECN | NETIF_F_TSO | \
NETIF_F_TSO6 | NETIF_F_UFO)
#define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
static struct macvlan_dev *macvtap_get_vlan_rcu(const struct net_device *dev)
{
return rcu_dereference(dev->rx_handler_data);
}
/*
* RCU usage:
* The macvtap_queue and the macvlan_dev are loosely coupled, the
* pointers from one to the other can only be read while rcu_read_lock
* or rtnl is held.
*
* Both the file and the macvlan_dev hold a reference on the macvtap_queue
* through sock_hold(&q->sk). When the macvlan_dev goes away first,
* q->vlan becomes inaccessible. When the files gets closed,
* macvtap_get_queue() fails.
*
* 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.
*/
static int macvtap_enable_queue(struct net_device *dev, struct file *file,
struct macvtap_queue *q)
{
struct macvlan_dev *vlan = netdev_priv(dev);
int err = -EINVAL;
ASSERT_RTNL();
if (q->enabled)
goto out;
err = 0;
rcu_assign_pointer(vlan->taps[vlan->numvtaps], q);
q->queue_index = vlan->numvtaps;
q->enabled = true;
vlan->numvtaps++;
out:
return err;
}
/* Requires RTNL */
static int macvtap_set_queue(struct net_device *dev, struct file *file,
struct macvtap_queue *q)
{
struct macvlan_dev *vlan = netdev_priv(dev);
if (vlan->numqueues == MAX_MACVTAP_QUEUES)
return -EBUSY;
rcu_assign_pointer(q->vlan, vlan);
rcu_assign_pointer(vlan->taps[vlan->numvtaps], q);
sock_hold(&q->sk);
q->file = file;
q->queue_index = vlan->numvtaps;
q->enabled = true;
file->private_data = q;
list_add_tail(&q->next, &vlan->queue_list);
vlan->numvtaps++;
vlan->numqueues++;
return 0;
}
static int macvtap_disable_queue(struct macvtap_queue *q)
{
struct macvlan_dev *vlan;
struct macvtap_queue *nq;
ASSERT_RTNL();
if (!q->enabled)
return -EINVAL;
vlan = rtnl_dereference(q->vlan);
if (vlan) {
int index = q->queue_index;
BUG_ON(index >= vlan->numvtaps);
nq = rtnl_dereference(vlan->taps[vlan->numvtaps - 1]);
nq->queue_index = index;
rcu_assign_pointer(vlan->taps[index], nq);
RCU_INIT_POINTER(vlan->taps[vlan->numvtaps - 1], NULL);
q->enabled = false;
vlan->numvtaps--;
}
return 0;
}
/*
* The file owning the queue got closed, give up both
* the reference that the files holds as well as the
* one from the macvlan_dev if that still exists.
*
* Using the spinlock makes sure that we don't get
* to the queue again after destroying it.
*/
static void macvtap_put_queue(struct macvtap_queue *q)
{
struct macvlan_dev *vlan;
rtnl_lock();
vlan = rtnl_dereference(q->vlan);
if (vlan) {
if (q->enabled)
BUG_ON(macvtap_disable_queue(q));
vlan->numqueues--;
RCU_INIT_POINTER(q->vlan, NULL);
sock_put(&q->sk);
list_del_init(&q->next);
}
rtnl_unlock();
synchronize_rcu();
sock_put(&q->sk);
}
/*
* Select a queue based on the rxq of the device on which this packet
* arrived. If the incoming device is not mq, calculate a flow hash
* to select a queue. If all fails, find the first available queue.
* Cache vlan->numvtaps since it can become zero during the execution
* of this function.
*/
static struct macvtap_queue *macvtap_get_queue(struct net_device *dev,
struct sk_buff *skb)
{
struct macvlan_dev *vlan = netdev_priv(dev);
struct macvtap_queue *tap = NULL;
/* Access to taps array is protected by rcu, but access to numvtaps
* isn't. Below we use it to lookup a queue, but treat it as a hint
* and validate that the result isn't NULL - in case we are
* racing against queue removal.
*/
int numvtaps = ACCESS_ONCE(vlan->numvtaps);
__u32 rxq;
if (!numvtaps)
goto out;
/* Check if we can use flow to select a queue */
rxq = skb_get_hash(skb);
if (rxq) {
tap = rcu_dereference(vlan->taps[rxq % numvtaps]);
goto out;
}
if (likely(skb_rx_queue_recorded(skb))) {
rxq = skb_get_rx_queue(skb);
while (unlikely(rxq >= numvtaps))
rxq -= numvtaps;
tap = rcu_dereference(vlan->taps[rxq]);
goto out;
}
tap = rcu_dereference(vlan->taps[0]);
out:
return tap;
}
/*
* The net_device is going away, give up the reference
* that it holds on all queues and safely set the pointer
* from the queues to NULL.
*/
static void macvtap_del_queues(struct net_device *dev)
{
struct macvlan_dev *vlan = netdev_priv(dev);
struct macvtap_queue *q, *tmp;
ASSERT_RTNL();
list_for_each_entry_safe(q, tmp, &vlan->queue_list, next) {
list_del_init(&q->next);
RCU_INIT_POINTER(q->vlan, NULL);
if (q->enabled)
vlan->numvtaps--;
vlan->numqueues--;
sock_put(&q->sk);
}
BUG_ON(vlan->numvtaps);
BUG_ON(vlan->numqueues);
/* guarantee that any future macvtap_set_queue will fail */
vlan->numvtaps = MAX_MACVTAP_QUEUES;
}
static rx_handler_result_t macvtap_handle_frame(struct sk_buff **pskb)
{
struct sk_buff *skb = *pskb;
struct net_device *dev = skb->dev;
struct macvlan_dev *vlan;
struct macvtap_queue *q;
netdev_features_t features = TAP_FEATURES;
vlan = macvtap_get_vlan_rcu(dev);
if (!vlan)
return RX_HANDLER_PASS;
q = macvtap_get_queue(dev, skb);
if (!q)
return RX_HANDLER_PASS;
if (skb_queue_len(&q->sk.sk_receive_queue) >= dev->tx_queue_len)
goto drop;
skb_push(skb, ETH_HLEN);
/* Apply the forward feature mask so that we perform segmentation
* according to users wishes. This only works if VNET_HDR is
* enabled.
*/
if (q->flags & IFF_VNET_HDR)
features |= vlan->tap_features;
if (netif_needs_gso(skb, features)) {
struct sk_buff *segs = __skb_gso_segment(skb, features, false);
if (IS_ERR(segs))
goto drop;
if (!segs) {
skb_queue_tail(&q->sk.sk_receive_queue, skb);
goto wake_up;
}
kfree_skb(skb);
while (segs) {
struct sk_buff *nskb = segs->next;
segs->next = NULL;
skb_queue_tail(&q->sk.sk_receive_queue, segs);
segs = nskb;
}
} else {
/* If we receive a partial checksum and the tap side
* doesn't support checksum offload, compute the checksum.
* Note: it doesn't matter which checksum feature to
* check, we either support them all or none.
*/
if (skb->ip_summed == CHECKSUM_PARTIAL &&
!(features & NETIF_F_CSUM_MASK) &&
skb_checksum_help(skb))
goto drop;
skb_queue_tail(&q->sk.sk_receive_queue, skb);
}
wake_up:
wake_up_interruptible_poll(sk_sleep(&q->sk), POLLIN | POLLRDNORM | POLLRDBAND);
return RX_HANDLER_CONSUMED;
drop:
/* Count errors/drops only here, thus don't care about args. */
macvlan_count_rx(vlan, 0, 0, 0);
kfree_skb(skb);
return RX_HANDLER_CONSUMED;
}
static int macvtap_get_minor(struct macvlan_dev *vlan)
{
int retval = -ENOMEM;
mutex_lock(&minor_lock);
retval = idr_alloc(&minor_idr, vlan, 1, MACVTAP_NUM_DEVS, GFP_KERNEL);
if (retval >= 0) {
vlan->minor = retval;
} else if (retval == -ENOSPC) {
printk(KERN_ERR "too many macvtap devices\n");
retval = -EINVAL;
}
mutex_unlock(&minor_lock);
return retval < 0 ? retval : 0;
}
static void macvtap_free_minor(struct macvlan_dev *vlan)
{
mutex_lock(&minor_lock);
if (vlan->minor) {
idr_remove(&minor_idr, vlan->minor);
vlan->minor = 0;
}
mutex_unlock(&minor_lock);
}
static struct net_device *dev_get_by_macvtap_minor(int minor)
{
struct net_device *dev = NULL;
struct macvlan_dev *vlan;
mutex_lock(&minor_lock);
vlan = idr_find(&minor_idr, minor);
if (vlan) {
dev = vlan->dev;
dev_hold(dev);
}
mutex_unlock(&minor_lock);
return dev;
}
static int macvtap_newlink(struct net *src_net,
struct net_device *dev,
struct nlattr *tb[],
struct nlattr *data[])
{
struct macvlan_dev *vlan = netdev_priv(dev);
int err;
INIT_LIST_HEAD(&vlan->queue_list);
/* Since macvlan supports all offloads by default, make
* tap support all offloads also.
*/
vlan->tap_features = TUN_OFFLOADS;
err = netdev_rx_handler_register(dev, macvtap_handle_frame, vlan);
if (err)
return err;
/* Don't put anything that may fail after macvlan_common_newlink
* because we can't undo what it does.
*/
return macvlan_common_newlink(src_net, dev, tb, data);
}
static void macvtap_dellink(struct net_device *dev,
struct list_head *head)
{
netdev_rx_handler_unregister(dev);
macvtap_del_queues(dev);
macvlan_dellink(dev, head);
}
static void macvtap_setup(struct net_device *dev)
{
macvlan_common_setup(dev);
dev->tx_queue_len = TUN_READQ_SIZE;
}
static struct rtnl_link_ops macvtap_link_ops __read_mostly = {
.kind = "macvtap",
.setup = macvtap_setup,
.newlink = macvtap_newlink,
.dellink = macvtap_dellink,
};
static void macvtap_sock_write_space(struct sock *sk)
{
wait_queue_head_t *wqueue;
if (!sock_writeable(sk) ||
!test_and_clear_bit(SOCKWQ_ASYNC_NOSPACE, &sk->sk_socket->flags))
return;
wqueue = sk_sleep(sk);
if (wqueue && waitqueue_active(wqueue))
wake_up_interruptible_poll(wqueue, POLLOUT | POLLWRNORM | POLLWRBAND);
}
static void macvtap_sock_destruct(struct sock *sk)
{
skb_queue_purge(&sk->sk_receive_queue);
}
static int macvtap_open(struct inode *inode, struct file *file)
{
struct net *net = current->nsproxy->net_ns;
struct net_device *dev;
struct macvtap_queue *q;
int err = -ENODEV;
rtnl_lock();
dev = dev_get_by_macvtap_minor(iminor(inode));
if (!dev)
goto out;
err = -ENOMEM;
q = (struct macvtap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
&macvtap_proto, 0);
if (!q)
goto out;
RCU_INIT_POINTER(q->sock.wq, &q->wq);
init_waitqueue_head(&q->wq.wait);
q->sock.type = SOCK_RAW;
q->sock.state = SS_CONNECTED;
q->sock.file = file;
q->sock.ops = &macvtap_socket_ops;
sock_init_data(&q->sock, &q->sk);
q->sk.sk_write_space = macvtap_sock_write_space;
q->sk.sk_destruct = macvtap_sock_destruct;
q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
/*
* so far only KVM virtio_net uses macvtap, enable zero copy between
* guest kernel and host kernel when lower device supports zerocopy
*
* The macvlan supports zerocopy iff the lower device supports zero
* copy so we don't have to look at the lower device directly.
*/
if ((dev->features & NETIF_F_HIGHDMA) && (dev->features & NETIF_F_SG))
sock_set_flag(&q->sk, SOCK_ZEROCOPY);
err = macvtap_set_queue(dev, file, q);
if (err)
sock_put(&q->sk);
out:
if (dev)
dev_put(dev);
rtnl_unlock();
return err;
}
static int macvtap_release(struct inode *inode, struct file *file)
{
struct macvtap_queue *q = file->private_data;
macvtap_put_queue(q);
return 0;
}
static unsigned int macvtap_poll(struct file *file, poll_table * wait)
{
struct macvtap_queue *q = file->private_data;
unsigned int mask = POLLERR;
if (!q)
goto out;
mask = 0;
poll_wait(file, &q->wq.wait, wait);
if (!skb_queue_empty(&q->sk.sk_receive_queue))
mask |= POLLIN | POLLRDNORM;
if (sock_writeable(&q->sk) ||
(!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
sock_writeable(&q->sk)))
mask |= POLLOUT | POLLWRNORM;
out:
return mask;
}
static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad,
size_t len, size_t linear,
int noblock, int *err)
{
struct sk_buff *skb;
/* Under a page? Don't bother with paged skb. */
if (prepad + len < PAGE_SIZE || !linear)
linear = len;
skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
err, 0);
if (!skb)
return NULL;
skb_reserve(skb, prepad);
skb_put(skb, linear);
skb->data_len = len - linear;
skb->len += len - linear;
return skb;
}
/*
* macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should
* be shared with the tun/tap driver.
*/
static int macvtap_skb_from_vnet_hdr(struct macvtap_queue *q,
struct sk_buff *skb,
struct virtio_net_hdr *vnet_hdr)
{
unsigned short gso_type = 0;
if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
switch (vnet_hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
case VIRTIO_NET_HDR_GSO_TCPV4:
gso_type = SKB_GSO_TCPV4;
break;
case VIRTIO_NET_HDR_GSO_TCPV6:
gso_type = SKB_GSO_TCPV6;
break;
case VIRTIO_NET_HDR_GSO_UDP:
gso_type = SKB_GSO_UDP;
break;
default:
return -EINVAL;
}
if (vnet_hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
gso_type |= SKB_GSO_TCP_ECN;
if (vnet_hdr->gso_size == 0)
return -EINVAL;
}
if (vnet_hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
if (!skb_partial_csum_set(skb, macvtap16_to_cpu(q, vnet_hdr->csum_start),
macvtap16_to_cpu(q, vnet_hdr->csum_offset)))
return -EINVAL;
}
if (vnet_hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
skb_shinfo(skb)->gso_size = macvtap16_to_cpu(q, vnet_hdr->gso_size);
skb_shinfo(skb)->gso_type = gso_type;
/* Header must be checked, and gso_segs computed. */
skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
skb_shinfo(skb)->gso_segs = 0;
}
return 0;
}
static void macvtap_skb_to_vnet_hdr(struct macvtap_queue *q,
const struct sk_buff *skb,
struct virtio_net_hdr *vnet_hdr)
{
memset(vnet_hdr, 0, sizeof(*vnet_hdr));
if (skb_is_gso(skb)) {
struct skb_shared_info *sinfo = skb_shinfo(skb);
/* This is a hint as to how much should be linear. */
vnet_hdr->hdr_len = cpu_to_macvtap16(q, skb_headlen(skb));
vnet_hdr->gso_size = cpu_to_macvtap16(q, sinfo->gso_size);
if (sinfo->gso_type & SKB_GSO_TCPV4)
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
else if (sinfo->gso_type & SKB_GSO_TCPV6)
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
else if (sinfo->gso_type & SKB_GSO_UDP)
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
else
BUG();
if (sinfo->gso_type & SKB_GSO_TCP_ECN)
vnet_hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
} else
vnet_hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
if (skb->ip_summed == CHECKSUM_PARTIAL) {
vnet_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
if (skb_vlan_tag_present(skb))
vnet_hdr->csum_start = cpu_to_macvtap16(q,
skb_checksum_start_offset(skb) + VLAN_HLEN);
else
vnet_hdr->csum_start = cpu_to_macvtap16(q,
skb_checksum_start_offset(skb));
vnet_hdr->csum_offset = cpu_to_macvtap16(q, skb->csum_offset);
} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
vnet_hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
} /* else everything is zero */
}
/* Neighbour code has some assumptions on HH_DATA_MOD alignment */
#define MACVTAP_RESERVE HH_DATA_OFF(ETH_HLEN)
/* Get packet from user space buffer */
static ssize_t macvtap_get_user(struct macvtap_queue *q, struct msghdr *m,
struct iov_iter *from, int noblock)
{
int good_linear = SKB_MAX_HEAD(MACVTAP_RESERVE);
struct sk_buff *skb;
struct macvlan_dev *vlan;
unsigned long total_len = iov_iter_count(from);
unsigned long len = total_len;
int err;
struct virtio_net_hdr vnet_hdr = { 0 };
int vnet_hdr_len = 0;
int copylen = 0;
int depth;
bool zerocopy = false;
size_t linear;
ssize_t n;
if (q->flags & IFF_VNET_HDR) {
vnet_hdr_len = q->vnet_hdr_sz;
err = -EINVAL;
if (len < vnet_hdr_len)
goto err;
len -= vnet_hdr_len;
err = -EFAULT;
n = copy_from_iter(&vnet_hdr, sizeof(vnet_hdr), from);
if (n != sizeof(vnet_hdr))
goto err;
iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
macvtap16_to_cpu(q, vnet_hdr.csum_start) +
macvtap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
macvtap16_to_cpu(q, vnet_hdr.hdr_len))
vnet_hdr.hdr_len = cpu_to_macvtap16(q,
macvtap16_to_cpu(q, vnet_hdr.csum_start) +
macvtap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
err = -EINVAL;
if (macvtap16_to_cpu(q, vnet_hdr.hdr_len) > len)
goto err;
}
err = -EINVAL;
if (unlikely(len < ETH_HLEN))
goto err;
if (m && m->msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
struct iov_iter i;
copylen = vnet_hdr.hdr_len ?
macvtap16_to_cpu(q, vnet_hdr.hdr_len) : GOODCOPY_LEN;
if (copylen > good_linear)
copylen = good_linear;
else if (copylen < ETH_HLEN)
copylen = ETH_HLEN;
linear = copylen;
i = *from;
iov_iter_advance(&i, copylen);
if (iov_iter_npages(&i, INT_MAX) <= MAX_SKB_FRAGS)
zerocopy = true;
}
if (!zerocopy) {
copylen = len;
linear = macvtap16_to_cpu(q, vnet_hdr.hdr_len);
if (linear > good_linear)
linear = good_linear;
else if (linear < ETH_HLEN)
linear = ETH_HLEN;
}
skb = macvtap_alloc_skb(&q->sk, MACVTAP_RESERVE, copylen,
linear, noblock, &err);
if (!skb)
goto err;
if (zerocopy)
err = zerocopy_sg_from_iter(skb, from);
else {
err = skb_copy_datagram_from_iter(skb, 0, from, len);
if (!err && m && m->msg_control) {
struct ubuf_info *uarg = m->msg_control;
uarg->callback(uarg, false);
}
}
if (err)
goto err_kfree;
skb_set_network_header(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb->protocol = eth_hdr(skb)->h_proto;
if (vnet_hdr_len) {
err = macvtap_skb_from_vnet_hdr(q, skb, &vnet_hdr);
if (err)
goto err_kfree;
}
skb_probe_transport_header(skb, ETH_HLEN);
/* Move network header to the right position for VLAN tagged packets */
if ((skb->protocol == htons(ETH_P_8021Q) ||
skb->protocol == htons(ETH_P_8021AD)) &&
__vlan_get_protocol(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
rcu_read_lock();
vlan = rcu_dereference(q->vlan);
/* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) {
skb_shinfo(skb)->destructor_arg = m->msg_control;
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
skb_shinfo(skb)->tx_flags |= SKBTX_SHARED_FRAG;
}
if (vlan) {
skb->dev = vlan->dev;
dev_queue_xmit(skb);
} else {
kfree_skb(skb);
}
rcu_read_unlock();
return total_len;
err_kfree:
kfree_skb(skb);
err:
rcu_read_lock();
vlan = rcu_dereference(q->vlan);
if (vlan)
this_cpu_inc(vlan->pcpu_stats->tx_dropped);
rcu_read_unlock();
return err;
}
static ssize_t macvtap_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct macvtap_queue *q = file->private_data;
return macvtap_get_user(q, NULL, from, file->f_flags & O_NONBLOCK);
}
/* Put packet to the user space buffer */
static ssize_t macvtap_put_user(struct macvtap_queue *q,
const struct sk_buff *skb,
struct iov_iter *iter)
{
int ret;
int vnet_hdr_len = 0;
int vlan_offset = 0;
int total;
if (q->flags & IFF_VNET_HDR) {
struct virtio_net_hdr vnet_hdr;
vnet_hdr_len = q->vnet_hdr_sz;
if (iov_iter_count(iter) < vnet_hdr_len)
return -EINVAL;
macvtap_skb_to_vnet_hdr(q, skb, &vnet_hdr);
if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=
sizeof(vnet_hdr))
return -EFAULT;
iov_iter_advance(iter, vnet_hdr_len - sizeof(vnet_hdr));
}
total = vnet_hdr_len;
total += skb->len;
if (skb_vlan_tag_present(skb)) {
struct {
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
} veth;
veth.h_vlan_proto = skb->vlan_proto;
veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
total += VLAN_HLEN;
ret = skb_copy_datagram_iter(skb, 0, iter, vlan_offset);
if (ret || !iov_iter_count(iter))
goto done;
ret = copy_to_iter(&veth, sizeof(veth), iter);
if (ret != sizeof(veth) || !iov_iter_count(iter))
goto done;
}
ret = skb_copy_datagram_iter(skb, vlan_offset, iter,
skb->len - vlan_offset);
done:
return ret ? ret : total;
}
static ssize_t macvtap_do_read(struct macvtap_queue *q,
struct iov_iter *to,
int noblock)
{
DEFINE_WAIT(wait);
struct sk_buff *skb;
ssize_t ret = 0;
if (!iov_iter_count(to))
return 0;
while (1) {
if (!noblock)
prepare_to_wait(sk_sleep(&q->sk), &wait,
TASK_INTERRUPTIBLE);
/* Read frames from the queue */
skb = skb_dequeue(&q->sk.sk_receive_queue);
if (skb)
break;
if (noblock) {
ret = -EAGAIN;
break;
}
if (signal_pending(current)) {
ret = -ERESTARTSYS;
break;
}
/* Nothing to read, let's sleep */
schedule();
}
if (!noblock)
finish_wait(sk_sleep(&q->sk), &wait);
if (skb) {
ret = macvtap_put_user(q, skb, to);
if (unlikely(ret < 0))
kfree_skb(skb);
else
consume_skb(skb);
}
return ret;
}
static ssize_t macvtap_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct macvtap_queue *q = file->private_data;
ssize_t len = iov_iter_count(to), ret;
ret = macvtap_do_read(q, to, file->f_flags & O_NONBLOCK);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
iocb->ki_pos = ret;
return ret;
}
static struct macvlan_dev *macvtap_get_vlan(struct macvtap_queue *q)
{
struct macvlan_dev *vlan;
ASSERT_RTNL();
vlan = rtnl_dereference(q->vlan);
if (vlan)
dev_hold(vlan->dev);
return vlan;
}
static void macvtap_put_vlan(struct macvlan_dev *vlan)
{
dev_put(vlan->dev);
}
static int macvtap_ioctl_set_queue(struct file *file, unsigned int flags)
{
struct macvtap_queue *q = file->private_data;
struct macvlan_dev *vlan;
int ret;
vlan = macvtap_get_vlan(q);
if (!vlan)
return -EINVAL;
if (flags & IFF_ATTACH_QUEUE)
ret = macvtap_enable_queue(vlan->dev, file, q);
else if (flags & IFF_DETACH_QUEUE)
ret = macvtap_disable_queue(q);
else
ret = -EINVAL;
macvtap_put_vlan(vlan);
return ret;
}
static int set_offload(struct macvtap_queue *q, unsigned long arg)
{
struct macvlan_dev *vlan;
netdev_features_t features;
netdev_features_t feature_mask = 0;
vlan = rtnl_dereference(q->vlan);
if (!vlan)
return -ENOLINK;
features = vlan->dev->features;
if (arg & TUN_F_CSUM) {
feature_mask = NETIF_F_HW_CSUM;
if (arg & (TUN_F_TSO4 | TUN_F_TSO6)) {
if (arg & TUN_F_TSO_ECN)
feature_mask |= NETIF_F_TSO_ECN;
if (arg & TUN_F_TSO4)
feature_mask |= NETIF_F_TSO;
if (arg & TUN_F_TSO6)
feature_mask |= NETIF_F_TSO6;
}
if (arg & TUN_F_UFO)
feature_mask |= NETIF_F_UFO;
}
/* tun/tap driver inverts the usage for TSO offloads, where
* setting the TSO bit means that the userspace wants to
* accept TSO frames and turning it off means that user space
* does not support TSO.
* For macvtap, we have to invert it to mean the same thing.
* When user space turns off TSO, we turn off GSO/LRO so that
* user-space will not receive TSO frames.
*/
if (feature_mask & (NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_UFO))
features |= RX_OFFLOADS;
else
features &= ~RX_OFFLOADS;
/* tap_features are the same as features on tun/tap and
* reflect user expectations.
*/
vlan->tap_features = feature_mask;
vlan->set_features = features;
netdev_update_features(vlan->dev);
return 0;
}
/*
* provide compatibility with generic tun/tap interface
*/
static long macvtap_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct macvtap_queue *q = file->private_data;
struct macvlan_dev *vlan;
void __user *argp = (void __user *)arg;
struct ifreq __user *ifr = argp;
unsigned int __user *up = argp;
unsigned short u;
int __user *sp = argp;
struct sockaddr sa;
int s;
int ret;
switch (cmd) {
case TUNSETIFF:
/* ignore the name, just look at flags */
if (get_user(u, &ifr->ifr_flags))
return -EFAULT;
ret = 0;
if ((u & ~MACVTAP_FEATURES) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
else
q->flags = (q->flags & ~MACVTAP_FEATURES) | u;
return ret;
case TUNGETIFF:
rtnl_lock();
vlan = macvtap_get_vlan(q);
if (!vlan) {
rtnl_unlock();
return -ENOLINK;
}
ret = 0;
u = q->flags;
if (copy_to_user(&ifr->ifr_name, vlan->dev->name, IFNAMSIZ) ||
put_user(u, &ifr->ifr_flags))
ret = -EFAULT;
macvtap_put_vlan(vlan);
rtnl_unlock();
return ret;
case TUNSETQUEUE:
if (get_user(u, &ifr->ifr_flags))
return -EFAULT;
rtnl_lock();
ret = macvtap_ioctl_set_queue(file, u);
rtnl_unlock();
return ret;
case TUNGETFEATURES:
if (put_user(IFF_TAP | IFF_NO_PI | MACVTAP_FEATURES, up))
return -EFAULT;
return 0;
case TUNSETSNDBUF:
if (get_user(s, sp))
return -EFAULT;
q->sk.sk_sndbuf = s;
return 0;
case TUNGETVNETHDRSZ:
s = q->vnet_hdr_sz;
if (put_user(s, sp))
return -EFAULT;
return 0;
case TUNSETVNETHDRSZ:
if (get_user(s, sp))
return -EFAULT;
if (s < (int)sizeof(struct virtio_net_hdr))
return -EINVAL;
q->vnet_hdr_sz = s;
return 0;
case TUNGETVNETLE:
s = !!(q->flags & MACVTAP_VNET_LE);
if (put_user(s, sp))
return -EFAULT;
return 0;
case TUNSETVNETLE:
if (get_user(s, sp))
return -EFAULT;
if (s)
q->flags |= MACVTAP_VNET_LE;
else
q->flags &= ~MACVTAP_VNET_LE;
return 0;
case TUNGETVNETBE:
return macvtap_get_vnet_be(q, sp);
case TUNSETVNETBE:
return macvtap_set_vnet_be(q, sp);
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;
rtnl_lock();
ret = set_offload(q, arg);
rtnl_unlock();
return ret;
case SIOCGIFHWADDR:
rtnl_lock();
vlan = macvtap_get_vlan(q);
if (!vlan) {
rtnl_unlock();
return -ENOLINK;
}
ret = 0;
u = vlan->dev->type;
if (copy_to_user(&ifr->ifr_name, vlan->dev->name, IFNAMSIZ) ||
copy_to_user(&ifr->ifr_hwaddr.sa_data, vlan->dev->dev_addr, ETH_ALEN) ||
put_user(u, &ifr->ifr_hwaddr.sa_family))
ret = -EFAULT;
macvtap_put_vlan(vlan);
rtnl_unlock();
return ret;
case SIOCSIFHWADDR:
if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
return -EFAULT;
rtnl_lock();
vlan = macvtap_get_vlan(q);
if (!vlan) {
rtnl_unlock();
return -ENOLINK;
}
ret = dev_set_mac_address(vlan->dev, &sa);
macvtap_put_vlan(vlan);
rtnl_unlock();
return ret;
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,
.read_iter = macvtap_read_iter,
.write_iter = macvtap_write_iter,
.poll = macvtap_poll,
.llseek = no_llseek,
.unlocked_ioctl = macvtap_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = macvtap_compat_ioctl,
#endif
};
static int macvtap_sendmsg(struct socket *sock, struct msghdr *m,
size_t total_len)
{
struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
return macvtap_get_user(q, m, &m->msg_iter, m->msg_flags & MSG_DONTWAIT);
}
static int macvtap_recvmsg(struct socket *sock, struct msghdr *m,
size_t total_len, int flags)
{
struct macvtap_queue *q = container_of(sock, struct macvtap_queue, sock);
int ret;
if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
return -EINVAL;
ret = macvtap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT);
if (ret > total_len) {
m->msg_flags |= MSG_TRUNC;
ret = flags & MSG_TRUNC ? ret : total_len;
}
return ret;
}
/* Ops structure to mimic raw sockets with tun */
static const struct proto_ops macvtap_socket_ops = {
.sendmsg = macvtap_sendmsg,
.recvmsg = macvtap_recvmsg,
};
/* Get an underlying socket object from tun file. Returns error unless file is
* attached to a device. The returned object works like a packet socket, it
* can be used for sock_sendmsg/sock_recvmsg. The caller is responsible for
* holding a reference to the file for as long as the socket is in use. */
struct socket *macvtap_get_socket(struct file *file)
{
struct macvtap_queue *q;
if (file->f_op != &macvtap_fops)
return ERR_PTR(-EINVAL);
q = file->private_data;
if (!q)
return ERR_PTR(-EBADFD);
return &q->sock;
}
EXPORT_SYMBOL_GPL(macvtap_get_socket);
static int macvtap_device_event(struct notifier_block *unused,
unsigned long event, void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct macvlan_dev *vlan;
struct device *classdev;
dev_t devt;
int err;
char tap_name[IFNAMSIZ];
if (dev->rtnl_link_ops != &macvtap_link_ops)
return NOTIFY_DONE;
snprintf(tap_name, IFNAMSIZ, "tap%d", dev->ifindex);
vlan = netdev_priv(dev);
switch (event) {
case NETDEV_REGISTER:
/* Create the device node here after the network device has
* been registered but before register_netdevice has
* finished running.
*/
err = macvtap_get_minor(vlan);
if (err)
return notifier_from_errno(err);
devt = MKDEV(MAJOR(macvtap_major), vlan->minor);
classdev = device_create(&macvtap_class, &dev->dev, devt,
dev, tap_name);
if (IS_ERR(classdev)) {
macvtap_free_minor(vlan);
return notifier_from_errno(PTR_ERR(classdev));
}
err = sysfs_create_link(&dev->dev.kobj, &classdev->kobj,
tap_name);
if (err)
return notifier_from_errno(err);
break;
case NETDEV_UNREGISTER:
/* vlan->minor == 0 if NETDEV_REGISTER above failed */
if (vlan->minor == 0)
break;
sysfs_remove_link(&dev->dev.kobj, tap_name);
devt = MKDEV(MAJOR(macvtap_major), vlan->minor);
device_destroy(&macvtap_class, devt);
macvtap_free_minor(vlan);
break;
}
return NOTIFY_DONE;
}
static struct notifier_block macvtap_notifier_block __read_mostly = {
.notifier_call = macvtap_device_event,
};
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;
err = class_register(&macvtap_class);
if (err)
goto out3;
err = register_netdevice_notifier(&macvtap_notifier_block);
if (err)
goto out4;
err = macvlan_link_register(&macvtap_link_ops);
if (err)
goto out5;
return 0;
out5:
unregister_netdevice_notifier(&macvtap_notifier_block);
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);
unregister_netdevice_notifier(&macvtap_notifier_block);
class_unregister(&macvtap_class);
cdev_del(&macvtap_cdev);
unregister_chrdev_region(macvtap_major, MACVTAP_NUM_DEVS);
idr_destroy(&minor_idr);
}
module_exit(macvtap_exit);
MODULE_ALIAS_RTNL_LINK("macvtap");
MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
MODULE_LICENSE("GPL");