// SPDX-License-Identifier: GPL-2.0-only
#include <linux/etherdevice.h>
#include <linux/if_tap.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/signal.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/gso.h>
#include <net/net_namespace.h>
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <net/xdp.h>
#include <linux/virtio_net.h>
#include <linux/skb_array.h>
#define TAP_IFFEATURES (IFF_VNET_HDR | IFF_MULTI_QUEUE)
#define TAP_VNET_LE 0x80000000
#define TAP_VNET_BE 0x40000000
#ifdef CONFIG_TUN_VNET_CROSS_LE
static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
{
return q->flags & TAP_VNET_BE ? false :
virtio_legacy_is_little_endian();
}
static long tap_get_vnet_be(struct tap_queue *q, int __user *sp)
{
int s = !!(q->flags & TAP_VNET_BE);
if (put_user(s, sp))
return -EFAULT;
return 0;
}
static long tap_set_vnet_be(struct tap_queue *q, int __user *sp)
{
int s;
if (get_user(s, sp))
return -EFAULT;
if (s)
q->flags |= TAP_VNET_BE;
else
q->flags &= ~TAP_VNET_BE;
return 0;
}
#else
static inline bool tap_legacy_is_little_endian(struct tap_queue *q)
{
return virtio_legacy_is_little_endian();
}
static long tap_get_vnet_be(struct tap_queue *q, int __user *argp)
{
return -EINVAL;
}
static long tap_set_vnet_be(struct tap_queue *q, int __user *argp)
{
return -EINVAL;
}
#endif /* CONFIG_TUN_VNET_CROSS_LE */
static inline bool tap_is_little_endian(struct tap_queue *q)
{
return q->flags & TAP_VNET_LE ||
tap_legacy_is_little_endian(q);
}
static inline u16 tap16_to_cpu(struct tap_queue *q, __virtio16 val)
{
return __virtio16_to_cpu(tap_is_little_endian(q), val);
}
static inline __virtio16 cpu_to_tap16(struct tap_queue *q, u16 val)
{
return __cpu_to_virtio16(tap_is_little_endian(q), val);
}
static struct proto tap_proto = {
.name = "tap",
.owner = THIS_MODULE,
.obj_size = sizeof(struct tap_queue),
};
#define TAP_NUM_DEVS (1U << MINORBITS)
static LIST_HEAD(major_list);
struct major_info {
struct rcu_head rcu;
dev_t major;
struct idr minor_idr;
spinlock_t minor_lock;
const char *device_name;
struct list_head next;
};
#define GOODCOPY_LEN 128
static const struct proto_ops tap_socket_ops;
#define RX_OFFLOADS (NETIF_F_GRO | NETIF_F_LRO)
#define TAP_FEATURES (NETIF_F_GSO | NETIF_F_SG | NETIF_F_FRAGLIST)
static struct tap_dev *tap_dev_get_rcu(const struct net_device *dev)
{
return rcu_dereference(dev->rx_handler_data);
}
/*
* RCU usage:
* The tap_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 tap_queue
* through sock_hold(&q->sk). When the macvlan_dev goes away first,
* q->vlan becomes inaccessible. When the files gets closed,
* tap_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 tap_enable_queue(struct tap_dev *tap, struct file *file,
struct tap_queue *q)
{
int err = -EINVAL;
ASSERT_RTNL();
if (q->enabled)
goto out;
err = 0;
rcu_assign_pointer(tap->taps[tap->numvtaps], q);
q->queue_index = tap->numvtaps;
q->enabled = true;
tap->numvtaps++;
out:
return err;
}
/* Requires RTNL */
static int tap_set_queue(struct tap_dev *tap, struct file *file,
struct tap_queue *q)
{
if (tap->numqueues == MAX_TAP_QUEUES)
return -EBUSY;
rcu_assign_pointer(q->tap, tap);
rcu_assign_pointer(tap->taps[tap->numvtaps], q);
sock_hold(&q->sk);
q->file = file;
q->queue_index = tap->numvtaps;
q->enabled = true;
file->private_data = q;
list_add_tail(&q->next, &tap->queue_list);
tap->numvtaps++;
tap->numqueues++;
return 0;
}
static int tap_disable_queue(struct tap_queue *q)
{
struct tap_dev *tap;
struct tap_queue *nq;
ASSERT_RTNL();
if (!q->enabled)
return -EINVAL;
tap = rtnl_dereference(q->tap);
if (tap) {
int index = q->queue_index;
BUG_ON(index >= tap->numvtaps);
nq = rtnl_dereference(tap->taps[tap->numvtaps - 1]);
nq->queue_index = index;
rcu_assign_pointer(tap->taps[index], nq);
RCU_INIT_POINTER(tap->taps[tap->numvtaps - 1], NULL);
q->enabled = false;
tap->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 tap_put_queue(struct tap_queue *q)
{
struct tap_dev *tap;
rtnl_lock();
tap = rtnl_dereference(q->tap);
if (tap) {
if (q->enabled)
BUG_ON(tap_disable_queue(q));
tap->numqueues--;
RCU_INIT_POINTER(q->tap, 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 tap_queue *tap_get_queue(struct tap_dev *tap,
struct sk_buff *skb)
{
struct tap_queue *queue = 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 = READ_ONCE(tap->numvtaps);
__u32 rxq;
if (!numvtaps)
goto out;
if (numvtaps == 1)
goto single;
/* Check if we can use flow to select a queue */
rxq = skb_get_hash(skb);
if (rxq) {
queue = rcu_dereference(tap->taps[rxq % numvtaps]);
goto out;
}
if (likely(skb_rx_queue_recorded(skb))) {
rxq = skb_get_rx_queue(skb);
while (unlikely(rxq >= numvtaps))
rxq -= numvtaps;
queue = rcu_dereference(tap->taps[rxq]);
goto out;
}
single:
queue = rcu_dereference(tap->taps[0]);
out:
return queue;
}
/*
* 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.
*/
void tap_del_queues(struct tap_dev *tap)
{
struct tap_queue *q, *tmp;
ASSERT_RTNL();
list_for_each_entry_safe(q, tmp, &tap->queue_list, next) {
list_del_init(&q->next);
RCU_INIT_POINTER(q->tap, NULL);
if (q->enabled)
tap->numvtaps--;
tap->numqueues--;
sock_put(&q->sk);
}
BUG_ON(tap->numvtaps);
BUG_ON(tap->numqueues);
/* guarantee that any future tap_set_queue will fail */
tap->numvtaps = MAX_TAP_QUEUES;
}
EXPORT_SYMBOL_GPL(tap_del_queues);
rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
{
struct sk_buff *skb = *pskb;
struct net_device *dev = skb->dev;
struct tap_dev *tap;
struct tap_queue *q;
netdev_features_t features = TAP_FEATURES;
enum skb_drop_reason drop_reason;
tap = tap_dev_get_rcu(dev);
if (!tap)
return RX_HANDLER_PASS;
q = tap_get_queue(tap, skb);
if (!q)
return RX_HANDLER_PASS;
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 |= tap->tap_features;
if (netif_needs_gso(skb, features)) {
struct sk_buff *segs = __skb_gso_segment(skb, features, false);
struct sk_buff *next;
if (IS_ERR(segs)) {
drop_reason = SKB_DROP_REASON_SKB_GSO_SEG;
goto drop;
}
if (!segs) {
if (ptr_ring_produce(&q->ring, skb)) {
drop_reason = SKB_DROP_REASON_FULL_RING;
goto drop;
}
goto wake_up;
}
consume_skb(skb);
skb_list_walk_safe(segs, skb, next) {
skb_mark_not_on_list(skb);
if (ptr_ring_produce(&q->ring, skb)) {
drop_reason = SKB_DROP_REASON_FULL_RING;
kfree_skb_reason(skb, drop_reason);
kfree_skb_list_reason(next, drop_reason);
break;
}
}
} 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)) {
drop_reason = SKB_DROP_REASON_SKB_CSUM;
goto drop;
}
if (ptr_ring_produce(&q->ring, skb)) {
drop_reason = SKB_DROP_REASON_FULL_RING;
goto drop;
}
}
wake_up:
wake_up_interruptible_poll(sk_sleep(&q->sk), EPOLLIN | EPOLLRDNORM | EPOLLRDBAND);
return RX_HANDLER_CONSUMED;
drop:
/* Count errors/drops only here, thus don't care about args. */
if (tap->count_rx_dropped)
tap->count_rx_dropped(tap);
kfree_skb_reason(skb, drop_reason);
return RX_HANDLER_CONSUMED;
}
EXPORT_SYMBOL_GPL(tap_handle_frame);
static struct major_info *tap_get_major(int major)
{
struct major_info *tap_major;
list_for_each_entry_rcu(tap_major, &major_list, next) {
if (tap_major->major == major)
return tap_major;
}
return NULL;
}
int tap_get_minor(dev_t major, struct tap_dev *tap)
{
int retval = -ENOMEM;
struct major_info *tap_major;
rcu_read_lock();
tap_major = tap_get_major(MAJOR(major));
if (!tap_major) {
retval = -EINVAL;
goto unlock;
}
spin_lock(&tap_major->minor_lock);
retval = idr_alloc(&tap_major->minor_idr, tap, 1, TAP_NUM_DEVS, GFP_ATOMIC);
if (retval >= 0) {
tap->minor = retval;
} else if (retval == -ENOSPC) {
netdev_err(tap->dev, "Too many tap devices\n");
retval = -EINVAL;
}
spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
return retval < 0 ? retval : 0;
}
EXPORT_SYMBOL_GPL(tap_get_minor);
void tap_free_minor(dev_t major, struct tap_dev *tap)
{
struct major_info *tap_major;
rcu_read_lock();
tap_major = tap_get_major(MAJOR(major));
if (!tap_major) {
goto unlock;
}
spin_lock(&tap_major->minor_lock);
if (tap->minor) {
idr_remove(&tap_major->minor_idr, tap->minor);
tap->minor = 0;
}
spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(tap_free_minor);
static struct tap_dev *dev_get_by_tap_file(int major, int minor)
{
struct net_device *dev = NULL;
struct tap_dev *tap;
struct major_info *tap_major;
rcu_read_lock();
tap_major = tap_get_major(major);
if (!tap_major) {
tap = NULL;
goto unlock;
}
spin_lock(&tap_major->minor_lock);
tap = idr_find(&tap_major->minor_idr, minor);
if (tap) {
dev = tap->dev;
dev_hold(dev);
}
spin_unlock(&tap_major->minor_lock);
unlock:
rcu_read_unlock();
return tap;
}
static void tap_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, EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
}
static void tap_sock_destruct(struct sock *sk)
{
struct tap_queue *q = container_of(sk, struct tap_queue, sk);
ptr_ring_cleanup(&q->ring, __skb_array_destroy_skb);
}
static int tap_open(struct inode *inode, struct file *file)
{
struct net *net = current->nsproxy->net_ns;
struct tap_dev *tap;
struct tap_queue *q;
int err = -ENODEV;
rtnl_lock();
tap = dev_get_by_tap_file(imajor(inode), iminor(inode));
if (!tap)
goto err;
err = -ENOMEM;
q = (struct tap_queue *)sk_alloc(net, AF_UNSPEC, GFP_KERNEL,
&tap_proto, 0);
if (!q)
goto err;
if (ptr_ring_init(&q->ring, tap->dev->tx_queue_len, GFP_KERNEL)) {
sk_free(&q->sk);
goto err;
}
init_waitqueue_head(&q->sock.wq.wait);
q->sock.type = SOCK_RAW;
q->sock.state = SS_CONNECTED;
q->sock.file = file;
q->sock.ops = &tap_socket_ops;
sock_init_data_uid(&q->sock, &q->sk, current_fsuid());
q->sk.sk_write_space = tap_sock_write_space;
q->sk.sk_destruct = tap_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 tap, 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 ((tap->dev->features & NETIF_F_HIGHDMA) && (tap->dev->features & NETIF_F_SG))
sock_set_flag(&q->sk, SOCK_ZEROCOPY);
err = tap_set_queue(tap, file, q);
if (err) {
/* tap_sock_destruct() will take care of freeing ptr_ring */
goto err_put;
}
/* tap groks IOCB_NOWAIT just fine, mark it as such */
file->f_mode |= FMODE_NOWAIT;
dev_put(tap->dev);
rtnl_unlock();
return err;
err_put:
sock_put(&q->sk);
err:
if (tap)
dev_put(tap->dev);
rtnl_unlock();
return err;
}
static int tap_release(struct inode *inode, struct file *file)
{
struct tap_queue *q = file->private_data;
tap_put_queue(q);
return 0;
}
static __poll_t tap_poll(struct file *file, poll_table *wait)
{
struct tap_queue *q = file->private_data;
__poll_t mask = EPOLLERR;
if (!q)
goto out;
mask = 0;
poll_wait(file, &q->sock.wq.wait, wait);
if (!ptr_ring_empty(&q->ring))
mask |= EPOLLIN | EPOLLRDNORM;
if (sock_writeable(&q->sk) ||
(!test_and_set_bit(SOCKWQ_ASYNC_NOSPACE, &q->sock.flags) &&
sock_writeable(&q->sk)))
mask |= EPOLLOUT | EPOLLWRNORM;
out:
return mask;
}
static inline struct sk_buff *tap_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;
if (len - linear > MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
linear = len - MAX_SKB_FRAGS * (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER);
skb = sock_alloc_send_pskb(sk, prepad + linear, len - linear, noblock,
err, PAGE_ALLOC_COSTLY_ORDER);
if (!skb)
return NULL;
skb_reserve(skb, prepad);
skb_put(skb, linear);
skb->data_len = len - linear;
skb->len += len - linear;
return skb;
}
/* Neighbour code has some assumptions on HH_DATA_MOD alignment */
#define TAP_RESERVE HH_DATA_OFF(ETH_HLEN)
/* Get packet from user space buffer */
static ssize_t tap_get_user(struct tap_queue *q, void *msg_control,
struct iov_iter *from, int noblock)
{
int good_linear = SKB_MAX_HEAD(TAP_RESERVE);
struct sk_buff *skb;
struct tap_dev *tap;
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;
enum skb_drop_reason drop_reason;
if (q->flags & IFF_VNET_HDR) {
vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
err = -EINVAL;
if (len < vnet_hdr_len)
goto err;
len -= vnet_hdr_len;
err = -EFAULT;
if (!copy_from_iter_full(&vnet_hdr, sizeof(vnet_hdr), from))
goto err;
iov_iter_advance(from, vnet_hdr_len - sizeof(vnet_hdr));
if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
tap16_to_cpu(q, vnet_hdr.csum_start) +
tap16_to_cpu(q, vnet_hdr.csum_offset) + 2 >
tap16_to_cpu(q, vnet_hdr.hdr_len))
vnet_hdr.hdr_len = cpu_to_tap16(q,
tap16_to_cpu(q, vnet_hdr.csum_start) +
tap16_to_cpu(q, vnet_hdr.csum_offset) + 2);
err = -EINVAL;
if (tap16_to_cpu(q, vnet_hdr.hdr_len) > len)
goto err;
}
err = -EINVAL;
if (unlikely(len < ETH_HLEN))
goto err;
if (msg_control && sock_flag(&q->sk, SOCK_ZEROCOPY)) {
struct iov_iter i;
copylen = vnet_hdr.hdr_len ?
tap16_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 = tap16_to_cpu(q, vnet_hdr.hdr_len);
if (linear > good_linear)
linear = good_linear;
else if (linear < ETH_HLEN)
linear = ETH_HLEN;
}
skb = tap_alloc_skb(&q->sk, TAP_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) {
drop_reason = SKB_DROP_REASON_SKB_UCOPY_FAULT;
goto err_kfree;
}
skb_set_network_header(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb->protocol = eth_hdr(skb)->h_proto;
rcu_read_lock();
tap = rcu_dereference(q->tap);
if (!tap) {
kfree_skb(skb);
rcu_read_unlock();
return total_len;
}
skb->dev = tap->dev;
if (vnet_hdr_len) {
err = virtio_net_hdr_to_skb(skb, &vnet_hdr,
tap_is_little_endian(q));
if (err) {
rcu_read_unlock();
drop_reason = SKB_DROP_REASON_DEV_HDR;
goto err_kfree;
}
}
skb_probe_transport_header(skb);
/* Move network header to the right position for VLAN tagged packets */
if (eth_type_vlan(skb->protocol) &&
vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
/* copy skb_ubuf_info for callback when skb has no error */
if (zerocopy) {
skb_zcopy_init(skb, msg_control);
} else if (msg_control) {
struct ubuf_info *uarg = msg_control;
uarg->ops->complete(NULL, uarg, false);
}
dev_queue_xmit(skb);
rcu_read_unlock();
return total_len;
err_kfree:
kfree_skb_reason(skb, drop_reason);
err:
rcu_read_lock();
tap = rcu_dereference(q->tap);
if (tap && tap->count_tx_dropped)
tap->count_tx_dropped(tap);
rcu_read_unlock();
return err;
}
static ssize_t tap_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct tap_queue *q = file->private_data;
int noblock = 0;
if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
noblock = 1;
return tap_get_user(q, NULL, from, noblock);
}
/* Put packet to the user space buffer */
static ssize_t tap_put_user(struct tap_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) {
int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
struct virtio_net_hdr vnet_hdr;
vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
if (iov_iter_count(iter) < vnet_hdr_len)
return -EINVAL;
if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
tap_is_little_endian(q), true,
vlan_hlen))
BUG();
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 tap_do_read(struct tap_queue *q,
struct iov_iter *to,
int noblock, struct sk_buff *skb)
{
DEFINE_WAIT(wait);
ssize_t ret = 0;
if (!iov_iter_count(to)) {
kfree_skb(skb);
return 0;
}
if (skb)
goto put;
while (1) {
if (!noblock)
prepare_to_wait(sk_sleep(&q->sk), &wait,
TASK_INTERRUPTIBLE);
/* Read frames from the queue */
skb = ptr_ring_consume(&q->ring);
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);
put:
if (skb) {
ret = tap_put_user(q, skb, to);
if (unlikely(ret < 0))
kfree_skb(skb);
else
consume_skb(skb);
}
return ret;
}
static ssize_t tap_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct tap_queue *q = file->private_data;
ssize_t len = iov_iter_count(to), ret;
int noblock = 0;
if ((file->f_flags & O_NONBLOCK) || (iocb->ki_flags & IOCB_NOWAIT))
noblock = 1;
ret = tap_do_read(q, to, noblock, NULL);
ret = min_t(ssize_t, ret, len);
if (ret > 0)
iocb->ki_pos = ret;
return ret;
}
static struct tap_dev *tap_get_tap_dev(struct tap_queue *q)
{
struct tap_dev *tap;
ASSERT_RTNL();
tap = rtnl_dereference(q->tap);
if (tap)
dev_hold(tap->dev);
return tap;
}
static void tap_put_tap_dev(struct tap_dev *tap)
{
dev_put(tap->dev);
}
static int tap_ioctl_set_queue(struct file *file, unsigned int flags)
{
struct tap_queue *q = file->private_data;
struct tap_dev *tap;
int ret;
tap = tap_get_tap_dev(q);
if (!tap)
return -EINVAL;
if (flags & IFF_ATTACH_QUEUE)
ret = tap_enable_queue(tap, file, q);
else if (flags & IFF_DETACH_QUEUE)
ret = tap_disable_queue(q);
else
ret = -EINVAL;
tap_put_tap_dev(tap);
return ret;
}
static int set_offload(struct tap_queue *q, unsigned long arg)
{
struct tap_dev *tap;
netdev_features_t features;
netdev_features_t feature_mask = 0;
tap = rtnl_dereference(q->tap);
if (!tap)
return -ENOLINK;
features = tap->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;
}
/* TODO: for now USO4 and USO6 should work simultaneously */
if ((arg & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6))
features |= NETIF_F_GSO_UDP_L4;
}
/* 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 tap, 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) ||
(feature_mask & (TUN_F_USO4 | TUN_F_USO6)) == (TUN_F_USO4 | TUN_F_USO6))
features |= RX_OFFLOADS;
else
features &= ~RX_OFFLOADS;
/* tap_features are the same as features on tun/tap and
* reflect user expectations.
*/
tap->tap_features = feature_mask;
if (tap->update_features)
tap->update_features(tap, features);
return 0;
}
/*
* provide compatibility with generic tun/tap interface
*/
static long tap_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct tap_queue *q = file->private_data;
struct tap_dev *tap;
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 & ~TAP_IFFEATURES) != (IFF_NO_PI | IFF_TAP))
ret = -EINVAL;
else
q->flags = (q->flags & ~TAP_IFFEATURES) | u;
return ret;
case TUNGETIFF:
rtnl_lock();
tap = tap_get_tap_dev(q);
if (!tap) {
rtnl_unlock();
return -ENOLINK;
}
ret = 0;
u = q->flags;
if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
put_user(u, &ifr->ifr_flags))
ret = -EFAULT;
tap_put_tap_dev(tap);
rtnl_unlock();
return ret;
case TUNSETQUEUE:
if (get_user(u, &ifr->ifr_flags))
return -EFAULT;
rtnl_lock();
ret = tap_ioctl_set_queue(file, u);
rtnl_unlock();
return ret;
case TUNGETFEATURES:
if (put_user(IFF_TAP | IFF_NO_PI | TAP_IFFEATURES, up))
return -EFAULT;
return 0;
case TUNSETSNDBUF:
if (get_user(s, sp))
return -EFAULT;
if (s <= 0)
return -EINVAL;
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 & TAP_VNET_LE);
if (put_user(s, sp))
return -EFAULT;
return 0;
case TUNSETVNETLE:
if (get_user(s, sp))
return -EFAULT;
if (s)
q->flags |= TAP_VNET_LE;
else
q->flags &= ~TAP_VNET_LE;
return 0;
case TUNGETVNETBE:
return tap_get_vnet_be(q, sp);
case TUNSETVNETBE:
return tap_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 |
TUN_F_USO4 | TUN_F_USO6))
return -EINVAL;
rtnl_lock();
ret = set_offload(q, arg);
rtnl_unlock();
return ret;
case SIOCGIFHWADDR:
rtnl_lock();
tap = tap_get_tap_dev(q);
if (!tap) {
rtnl_unlock();
return -ENOLINK;
}
ret = 0;
dev_get_mac_address(&sa, dev_net(tap->dev), tap->dev->name);
if (copy_to_user(&ifr->ifr_name, tap->dev->name, IFNAMSIZ) ||
copy_to_user(&ifr->ifr_hwaddr, &sa, sizeof(sa)))
ret = -EFAULT;
tap_put_tap_dev(tap);
rtnl_unlock();
return ret;
case SIOCSIFHWADDR:
if (copy_from_user(&sa, &ifr->ifr_hwaddr, sizeof(sa)))
return -EFAULT;
rtnl_lock();
tap = tap_get_tap_dev(q);
if (!tap) {
rtnl_unlock();
return -ENOLINK;
}
ret = dev_set_mac_address_user(tap->dev, &sa, NULL);
tap_put_tap_dev(tap);
rtnl_unlock();
return ret;
default:
return -EINVAL;
}
}
static const struct file_operations tap_fops = {
.owner = THIS_MODULE,
.open = tap_open,
.release = tap_release,
.read_iter = tap_read_iter,
.write_iter = tap_write_iter,
.poll = tap_poll,
.unlocked_ioctl = tap_ioctl,
.compat_ioctl = compat_ptr_ioctl,
};
static int tap_get_user_xdp(struct tap_queue *q, struct xdp_buff *xdp)
{
struct tun_xdp_hdr *hdr = xdp->data_hard_start;
struct virtio_net_hdr *gso = &hdr->gso;
int buflen = hdr->buflen;
int vnet_hdr_len = 0;
struct tap_dev *tap;
struct sk_buff *skb;
int err, depth;
if (unlikely(xdp->data_end - xdp->data < ETH_HLEN)) {
err = -EINVAL;
goto err;
}
if (q->flags & IFF_VNET_HDR)
vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
skb = build_skb(xdp->data_hard_start, buflen);
if (!skb) {
err = -ENOMEM;
goto err;
}
skb_reserve(skb, xdp->data - xdp->data_hard_start);
skb_put(skb, xdp->data_end - xdp->data);
skb_set_network_header(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb->protocol = eth_hdr(skb)->h_proto;
if (vnet_hdr_len) {
err = virtio_net_hdr_to_skb(skb, gso, tap_is_little_endian(q));
if (err)
goto err_kfree;
}
/* Move network header to the right position for VLAN tagged packets */
if (eth_type_vlan(skb->protocol) &&
vlan_get_protocol_and_depth(skb, skb->protocol, &depth) != 0)
skb_set_network_header(skb, depth);
rcu_read_lock();
tap = rcu_dereference(q->tap);
if (tap) {
skb->dev = tap->dev;
skb_probe_transport_header(skb);
dev_queue_xmit(skb);
} else {
kfree_skb(skb);
}
rcu_read_unlock();
return 0;
err_kfree:
kfree_skb(skb);
err:
rcu_read_lock();
tap = rcu_dereference(q->tap);
if (tap && tap->count_tx_dropped)
tap->count_tx_dropped(tap);
rcu_read_unlock();
return err;
}
static int tap_sendmsg(struct socket *sock, struct msghdr *m,
size_t total_len)
{
struct tap_queue *q = container_of(sock, struct tap_queue, sock);
struct tun_msg_ctl *ctl = m->msg_control;
struct xdp_buff *xdp;
int i;
if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
ctl && ctl->type == TUN_MSG_PTR) {
for (i = 0; i < ctl->num; i++) {
xdp = &((struct xdp_buff *)ctl->ptr)[i];
tap_get_user_xdp(q, xdp);
}
return 0;
}
return tap_get_user(q, ctl ? ctl->ptr : NULL, &m->msg_iter,
m->msg_flags & MSG_DONTWAIT);
}
static int tap_recvmsg(struct socket *sock, struct msghdr *m,
size_t total_len, int flags)
{
struct tap_queue *q = container_of(sock, struct tap_queue, sock);
struct sk_buff *skb = m->msg_control;
int ret;
if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
kfree_skb(skb);
return -EINVAL;
}
ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
if (ret > total_len) {
m->msg_flags |= MSG_TRUNC;
ret = flags & MSG_TRUNC ? ret : total_len;
}
return ret;
}
static int tap_peek_len(struct socket *sock)
{
struct tap_queue *q = container_of(sock, struct tap_queue,
sock);
return PTR_RING_PEEK_CALL(&q->ring, __skb_array_len_with_tag);
}
/* Ops structure to mimic raw sockets with tun */
static const struct proto_ops tap_socket_ops = {
.sendmsg = tap_sendmsg,
.recvmsg = tap_recvmsg,
.peek_len = tap_peek_len,
};
/* 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 *tap_get_socket(struct file *file)
{
struct tap_queue *q;
if (file->f_op != &tap_fops)
return ERR_PTR(-EINVAL);
q = file->private_data;
if (!q)
return ERR_PTR(-EBADFD);
return &q->sock;
}
EXPORT_SYMBOL_GPL(tap_get_socket);
struct ptr_ring *tap_get_ptr_ring(struct file *file)
{
struct tap_queue *q;
if (file->f_op != &tap_fops)
return ERR_PTR(-EINVAL);
q = file->private_data;
if (!q)
return ERR_PTR(-EBADFD);
return &q->ring;
}
EXPORT_SYMBOL_GPL(tap_get_ptr_ring);
int tap_queue_resize(struct tap_dev *tap)
{
struct net_device *dev = tap->dev;
struct tap_queue *q;
struct ptr_ring **rings;
int n = tap->numqueues;
int ret, i = 0;
rings = kmalloc_array(n, sizeof(*rings), GFP_KERNEL);
if (!rings)
return -ENOMEM;
list_for_each_entry(q, &tap->queue_list, next)
rings[i++] = &q->ring;
ret = ptr_ring_resize_multiple(rings, n,
dev->tx_queue_len, GFP_KERNEL,
__skb_array_destroy_skb);
kfree(rings);
return ret;
}
EXPORT_SYMBOL_GPL(tap_queue_resize);
static int tap_list_add(dev_t major, const char *device_name)
{
struct major_info *tap_major;
tap_major = kzalloc(sizeof(*tap_major), GFP_ATOMIC);
if (!tap_major)
return -ENOMEM;
tap_major->major = MAJOR(major);
idr_init(&tap_major->minor_idr);
spin_lock_init(&tap_major->minor_lock);
tap_major->device_name = device_name;
list_add_tail_rcu(&tap_major->next, &major_list);
return 0;
}
int tap_create_cdev(struct cdev *tap_cdev, dev_t *tap_major,
const char *device_name, struct module *module)
{
int err;
err = alloc_chrdev_region(tap_major, 0, TAP_NUM_DEVS, device_name);
if (err)
goto out1;
cdev_init(tap_cdev, &tap_fops);
tap_cdev->owner = module;
err = cdev_add(tap_cdev, *tap_major, TAP_NUM_DEVS);
if (err)
goto out2;
err = tap_list_add(*tap_major, device_name);
if (err)
goto out3;
return 0;
out3:
cdev_del(tap_cdev);
out2:
unregister_chrdev_region(*tap_major, TAP_NUM_DEVS);
out1:
return err;
}
EXPORT_SYMBOL_GPL(tap_create_cdev);
void tap_destroy_cdev(dev_t major, struct cdev *tap_cdev)
{
struct major_info *tap_major, *tmp;
cdev_del(tap_cdev);
unregister_chrdev_region(major, TAP_NUM_DEVS);
list_for_each_entry_safe(tap_major, tmp, &major_list, next) {
if (tap_major->major == MAJOR(major)) {
idr_destroy(&tap_major->minor_idr);
list_del_rcu(&tap_major->next);
kfree_rcu(tap_major, rcu);
}
}
}
EXPORT_SYMBOL_GPL(tap_destroy_cdev);
MODULE_DESCRIPTION("Common library for drivers implementing the TAP interface");
MODULE_AUTHOR("Arnd Bergmann <[email protected]>");
MODULE_AUTHOR("Sainath Grandhi <[email protected]>");
MODULE_LICENSE("GPL");
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