diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/net/tap.c | 1404 |
1 files changed, 1404 insertions, 0 deletions
diff --git a/drivers/net/tap.c b/drivers/net/tap.c new file mode 100644 index 0000000000..5c01cc7b99 --- /dev/null +++ b/drivers/net/tap.c @@ -0,0 +1,1404 @@ +// 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->callback(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, + .llseek = no_llseek, + .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 (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_AUTHOR("Arnd Bergmann <arnd@arndb.de>"); +MODULE_AUTHOR("Sainath Grandhi <sainath.grandhi@intel.com>"); +MODULE_LICENSE("GPL"); |