Linux 5.7.7

[linux/fpc-iii.git] / net / xdp / xsk.c

// SPDX-License-Identifier: GPL-2.0
/* XDP sockets
 *
 * AF_XDP sockets allows a channel between XDP programs and userspace
 * applications.
 * Copyright(c) 2018 Intel Corporation.
 *
 * Author(s): Björn Töpel <bjorn.topel@intel.com>
 *            Magnus Karlsson <magnus.karlsson@intel.com>
 */

#define pr_fmt(fmt) "AF_XDP: %s: " fmt, __func__

#include <linux/if_xdp.h>
#include <linux/init.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/socket.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <net/xdp_sock.h>
#include <net/xdp.h>

#include "xsk_queue.h"
#include "xdp_umem.h"
#include "xsk.h"

#define TX_BATCH_SIZE 16

static DEFINE_PER_CPU(struct list_head, xskmap_flush_list);

bool xsk_is_setup_for_bpf_map(struct xdp_sock *xs)
{
        return READ_ONCE(xs->rx) &&  READ_ONCE(xs->umem) &&
                READ_ONCE(xs->umem->fq);
}

bool xsk_umem_has_addrs(struct xdp_umem *umem, u32 cnt)
{
        return xskq_cons_has_entries(umem->fq, cnt);
}
EXPORT_SYMBOL(xsk_umem_has_addrs);

bool xsk_umem_peek_addr(struct xdp_umem *umem, u64 *addr)
{
        return xskq_cons_peek_addr(umem->fq, addr, umem);
}
EXPORT_SYMBOL(xsk_umem_peek_addr);

void xsk_umem_release_addr(struct xdp_umem *umem)
{
        xskq_cons_release(umem->fq);
}
EXPORT_SYMBOL(xsk_umem_release_addr);

void xsk_set_rx_need_wakeup(struct xdp_umem *umem)
{
        if (umem->need_wakeup & XDP_WAKEUP_RX)
                return;

        umem->fq->ring->flags |= XDP_RING_NEED_WAKEUP;
        umem->need_wakeup |= XDP_WAKEUP_RX;
}
EXPORT_SYMBOL(xsk_set_rx_need_wakeup);

void xsk_set_tx_need_wakeup(struct xdp_umem *umem)
{
        struct xdp_sock *xs;

        if (umem->need_wakeup & XDP_WAKEUP_TX)
                return;

        rcu_read_lock();
        list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
                xs->tx->ring->flags |= XDP_RING_NEED_WAKEUP;
        }
        rcu_read_unlock();

        umem->need_wakeup |= XDP_WAKEUP_TX;
}
EXPORT_SYMBOL(xsk_set_tx_need_wakeup);

void xsk_clear_rx_need_wakeup(struct xdp_umem *umem)
{
        if (!(umem->need_wakeup & XDP_WAKEUP_RX))
                return;

        umem->fq->ring->flags &= ~XDP_RING_NEED_WAKEUP;
        umem->need_wakeup &= ~XDP_WAKEUP_RX;
}
EXPORT_SYMBOL(xsk_clear_rx_need_wakeup);

void xsk_clear_tx_need_wakeup(struct xdp_umem *umem)
{
        struct xdp_sock *xs;

        if (!(umem->need_wakeup & XDP_WAKEUP_TX))
                return;

        rcu_read_lock();
        list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
                xs->tx->ring->flags &= ~XDP_RING_NEED_WAKEUP;
        }
        rcu_read_unlock();

        umem->need_wakeup &= ~XDP_WAKEUP_TX;
}
EXPORT_SYMBOL(xsk_clear_tx_need_wakeup);

bool xsk_umem_uses_need_wakeup(struct xdp_umem *umem)
{
        return umem->flags & XDP_UMEM_USES_NEED_WAKEUP;
}
EXPORT_SYMBOL(xsk_umem_uses_need_wakeup);

/* If a buffer crosses a page boundary, we need to do 2 memcpy's, one for
 * each page. This is only required in copy mode.
 */
static void __xsk_rcv_memcpy(struct xdp_umem *umem, u64 addr, void *from_buf,
                             u32 len, u32 metalen)
{
        void *to_buf = xdp_umem_get_data(umem, addr);

        addr = xsk_umem_add_offset_to_addr(addr);
        if (xskq_cons_crosses_non_contig_pg(umem, addr, len + metalen)) {
                void *next_pg_addr = umem->pages[(addr >> PAGE_SHIFT) + 1].addr;
                u64 page_start = addr & ~(PAGE_SIZE - 1);
                u64 first_len = PAGE_SIZE - (addr - page_start);

                memcpy(to_buf, from_buf, first_len);
                memcpy(next_pg_addr, from_buf + first_len,
                       len + metalen - first_len);

                return;
        }

        memcpy(to_buf, from_buf, len + metalen);
}

static int __xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
{
        u64 offset = xs->umem->headroom;
        u64 addr, memcpy_addr;
        void *from_buf;
        u32 metalen;
        int err;

        if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
            len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
                xs->rx_dropped++;
                return -ENOSPC;
        }

        if (unlikely(xdp_data_meta_unsupported(xdp))) {
                from_buf = xdp->data;
                metalen = 0;
        } else {
                from_buf = xdp->data_meta;
                metalen = xdp->data - xdp->data_meta;
        }

        memcpy_addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
        __xsk_rcv_memcpy(xs->umem, memcpy_addr, from_buf, len, metalen);

        offset += metalen;
        addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
        err = xskq_prod_reserve_desc(xs->rx, addr, len);
        if (!err) {
                xskq_cons_release(xs->umem->fq);
                xdp_return_buff(xdp);
                return 0;
        }

        xs->rx_dropped++;
        return err;
}

static int __xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len)
{
        int err = xskq_prod_reserve_desc(xs->rx, xdp->handle, len);

        if (err)
                xs->rx_dropped++;

        return err;
}

static bool xsk_is_bound(struct xdp_sock *xs)
{
        if (READ_ONCE(xs->state) == XSK_BOUND) {
                /* Matches smp_wmb() in bind(). */
                smp_rmb();
                return true;
        }
        return false;
}

static int xsk_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
{
        u32 len;

        if (!xsk_is_bound(xs))
                return -EINVAL;

        if (xs->dev != xdp->rxq->dev || xs->queue_id != xdp->rxq->queue_index)
                return -EINVAL;

        len = xdp->data_end - xdp->data;

        return (xdp->rxq->mem.type == MEM_TYPE_ZERO_COPY) ?
                __xsk_rcv_zc(xs, xdp, len) : __xsk_rcv(xs, xdp, len);
}

static void xsk_flush(struct xdp_sock *xs)
{
        xskq_prod_submit(xs->rx);
        __xskq_cons_release(xs->umem->fq);
        sock_def_readable(&xs->sk);
}

int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp)
{
        u32 metalen = xdp->data - xdp->data_meta;
        u32 len = xdp->data_end - xdp->data;
        u64 offset = xs->umem->headroom;
        void *buffer;
        u64 addr;
        int err;

        spin_lock_bh(&xs->rx_lock);

        if (xs->dev != xdp->rxq->dev || xs->queue_id != xdp->rxq->queue_index) {
                err = -EINVAL;
                goto out_unlock;
        }

        if (!xskq_cons_peek_addr(xs->umem->fq, &addr, xs->umem) ||
            len > xs->umem->chunk_size_nohr - XDP_PACKET_HEADROOM) {
                err = -ENOSPC;
                goto out_drop;
        }

        addr = xsk_umem_adjust_offset(xs->umem, addr, offset);
        buffer = xdp_umem_get_data(xs->umem, addr);
        memcpy(buffer, xdp->data_meta, len + metalen);

        addr = xsk_umem_adjust_offset(xs->umem, addr, metalen);
        err = xskq_prod_reserve_desc(xs->rx, addr, len);
        if (err)
                goto out_drop;

        xskq_cons_release(xs->umem->fq);
        xskq_prod_submit(xs->rx);

        spin_unlock_bh(&xs->rx_lock);

        xs->sk.sk_data_ready(&xs->sk);
        return 0;

out_drop:
        xs->rx_dropped++;
out_unlock:
        spin_unlock_bh(&xs->rx_lock);
        return err;
}

int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp)
{
        struct list_head *flush_list = this_cpu_ptr(&xskmap_flush_list);
        int err;

        err = xsk_rcv(xs, xdp);
        if (err)
                return err;

        if (!xs->flush_node.prev)
                list_add(&xs->flush_node, flush_list);

        return 0;
}

void __xsk_map_flush(void)
{
        struct list_head *flush_list = this_cpu_ptr(&xskmap_flush_list);
        struct xdp_sock *xs, *tmp;

        list_for_each_entry_safe(xs, tmp, flush_list, flush_node) {
                xsk_flush(xs);
                __list_del_clearprev(&xs->flush_node);
        }
}

void xsk_umem_complete_tx(struct xdp_umem *umem, u32 nb_entries)
{
        xskq_prod_submit_n(umem->cq, nb_entries);
}
EXPORT_SYMBOL(xsk_umem_complete_tx);

void xsk_umem_consume_tx_done(struct xdp_umem *umem)
{
        struct xdp_sock *xs;

        rcu_read_lock();
        list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
                __xskq_cons_release(xs->tx);
                xs->sk.sk_write_space(&xs->sk);
        }
        rcu_read_unlock();
}
EXPORT_SYMBOL(xsk_umem_consume_tx_done);

bool xsk_umem_consume_tx(struct xdp_umem *umem, struct xdp_desc *desc)
{
        struct xdp_sock *xs;

        rcu_read_lock();
        list_for_each_entry_rcu(xs, &umem->xsk_list, list) {
                if (!xskq_cons_peek_desc(xs->tx, desc, umem))
                        continue;

                /* This is the backpreassure mechanism for the Tx path.
                 * Reserve space in the completion queue and only proceed
                 * if there is space in it. This avoids having to implement
                 * any buffering in the Tx path.
                 */
                if (xskq_prod_reserve_addr(umem->cq, desc->addr))
                        goto out;

                xskq_cons_release(xs->tx);
                rcu_read_unlock();
                return true;
        }

out:
        rcu_read_unlock();
        return false;
}
EXPORT_SYMBOL(xsk_umem_consume_tx);

static int xsk_wakeup(struct xdp_sock *xs, u8 flags)
{
        struct net_device *dev = xs->dev;
        int err;

        rcu_read_lock();
        err = dev->netdev_ops->ndo_xsk_wakeup(dev, xs->queue_id, flags);
        rcu_read_unlock();

        return err;
}

static int xsk_zc_xmit(struct xdp_sock *xs)
{
        return xsk_wakeup(xs, XDP_WAKEUP_TX);
}

static void xsk_destruct_skb(struct sk_buff *skb)
{
        u64 addr = (u64)(long)skb_shinfo(skb)->destructor_arg;
        struct xdp_sock *xs = xdp_sk(skb->sk);
        unsigned long flags;

        spin_lock_irqsave(&xs->tx_completion_lock, flags);
        xskq_prod_submit_addr(xs->umem->cq, addr);
        spin_unlock_irqrestore(&xs->tx_completion_lock, flags);

        sock_wfree(skb);
}

static int xsk_generic_xmit(struct sock *sk)
{
        struct xdp_sock *xs = xdp_sk(sk);
        u32 max_batch = TX_BATCH_SIZE;
        bool sent_frame = false;
        struct xdp_desc desc;
        struct sk_buff *skb;
        int err = 0;

        mutex_lock(&xs->mutex);

        if (xs->queue_id >= xs->dev->real_num_tx_queues)
                goto out;

        while (xskq_cons_peek_desc(xs->tx, &desc, xs->umem)) {
                char *buffer;
                u64 addr;
                u32 len;

                if (max_batch-- == 0) {
                        err = -EAGAIN;
                        goto out;
                }

                len = desc.len;
                skb = sock_alloc_send_skb(sk, len, 1, &err);
                if (unlikely(!skb))
                        goto out;

                skb_put(skb, len);
                addr = desc.addr;
                buffer = xdp_umem_get_data(xs->umem, addr);
                err = skb_store_bits(skb, 0, buffer, len);
                /* This is the backpreassure mechanism for the Tx path.
                 * Reserve space in the completion queue and only proceed
                 * if there is space in it. This avoids having to implement
                 * any buffering in the Tx path.
                 */
                if (unlikely(err) || xskq_prod_reserve(xs->umem->cq)) {
                        kfree_skb(skb);
                        goto out;
                }

                skb->dev = xs->dev;
                skb->priority = sk->sk_priority;
                skb->mark = sk->sk_mark;
                skb_shinfo(skb)->destructor_arg = (void *)(long)desc.addr;
                skb->destructor = xsk_destruct_skb;

                err = dev_direct_xmit(skb, xs->queue_id);
                xskq_cons_release(xs->tx);
                /* Ignore NET_XMIT_CN as packet might have been sent */
                if (err == NET_XMIT_DROP || err == NETDEV_TX_BUSY) {
                        /* SKB completed but not sent */
                        err = -EBUSY;
                        goto out;
                }

                sent_frame = true;
        }

out:
        if (sent_frame)
                sk->sk_write_space(sk);

        mutex_unlock(&xs->mutex);
        return err;
}

static int __xsk_sendmsg(struct sock *sk)
{
        struct xdp_sock *xs = xdp_sk(sk);

        if (unlikely(!(xs->dev->flags & IFF_UP)))
                return -ENETDOWN;
        if (unlikely(!xs->tx))
                return -ENOBUFS;

        return xs->zc ? xsk_zc_xmit(xs) : xsk_generic_xmit(sk);
}

static int xsk_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
{
        bool need_wait = !(m->msg_flags & MSG_DONTWAIT);
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);

        if (unlikely(!xsk_is_bound(xs)))
                return -ENXIO;
        if (unlikely(need_wait))
                return -EOPNOTSUPP;

        return __xsk_sendmsg(sk);
}

static __poll_t xsk_poll(struct file *file, struct socket *sock,
                             struct poll_table_struct *wait)
{
        __poll_t mask = datagram_poll(file, sock, wait);
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);
        struct xdp_umem *umem;

        if (unlikely(!xsk_is_bound(xs)))
                return mask;

        umem = xs->umem;

        if (umem->need_wakeup) {
                if (xs->zc)
                        xsk_wakeup(xs, umem->need_wakeup);
                else
                        /* Poll needs to drive Tx also in copy mode */
                        __xsk_sendmsg(sk);
        }

        if (xs->rx && !xskq_prod_is_empty(xs->rx))
                mask |= EPOLLIN | EPOLLRDNORM;
        if (xs->tx && !xskq_cons_is_full(xs->tx))
                mask |= EPOLLOUT | EPOLLWRNORM;

        return mask;
}

static int xsk_init_queue(u32 entries, struct xsk_queue **queue,
                          bool umem_queue)
{
        struct xsk_queue *q;

        if (entries == 0 || *queue || !is_power_of_2(entries))
                return -EINVAL;

        q = xskq_create(entries, umem_queue);
        if (!q)
                return -ENOMEM;

        /* Make sure queue is ready before it can be seen by others */
        smp_wmb();
        WRITE_ONCE(*queue, q);
        return 0;
}

static void xsk_unbind_dev(struct xdp_sock *xs)
{
        struct net_device *dev = xs->dev;

        if (xs->state != XSK_BOUND)
                return;
        WRITE_ONCE(xs->state, XSK_UNBOUND);

        /* Wait for driver to stop using the xdp socket. */
        xdp_del_sk_umem(xs->umem, xs);
        xs->dev = NULL;
        synchronize_net();
        dev_put(dev);
}

static struct xsk_map *xsk_get_map_list_entry(struct xdp_sock *xs,
                                              struct xdp_sock ***map_entry)
{
        struct xsk_map *map = NULL;
        struct xsk_map_node *node;

        *map_entry = NULL;

        spin_lock_bh(&xs->map_list_lock);
        node = list_first_entry_or_null(&xs->map_list, struct xsk_map_node,
                                        node);
        if (node) {
                WARN_ON(xsk_map_inc(node->map));
                map = node->map;
                *map_entry = node->map_entry;
        }
        spin_unlock_bh(&xs->map_list_lock);
        return map;
}

static void xsk_delete_from_maps(struct xdp_sock *xs)
{
        /* This function removes the current XDP socket from all the
         * maps it resides in. We need to take extra care here, due to
         * the two locks involved. Each map has a lock synchronizing
         * updates to the entries, and each socket has a lock that
         * synchronizes access to the list of maps (map_list). For
         * deadlock avoidance the locks need to be taken in the order
         * "map lock"->"socket map list lock". We start off by
         * accessing the socket map list, and take a reference to the
         * map to guarantee existence between the
         * xsk_get_map_list_entry() and xsk_map_try_sock_delete()
         * calls. Then we ask the map to remove the socket, which
         * tries to remove the socket from the map. Note that there
         * might be updates to the map between
         * xsk_get_map_list_entry() and xsk_map_try_sock_delete().
         */
        struct xdp_sock **map_entry = NULL;
        struct xsk_map *map;

        while ((map = xsk_get_map_list_entry(xs, &map_entry))) {
                xsk_map_try_sock_delete(map, xs, map_entry);
                xsk_map_put(map);
        }
}

static int xsk_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);
        struct net *net;

        if (!sk)
                return 0;

        net = sock_net(sk);

        mutex_lock(&net->xdp.lock);
        sk_del_node_init_rcu(sk);
        mutex_unlock(&net->xdp.lock);

        local_bh_disable();
        sock_prot_inuse_add(net, sk->sk_prot, -1);
        local_bh_enable();

        xsk_delete_from_maps(xs);
        mutex_lock(&xs->mutex);
        xsk_unbind_dev(xs);
        mutex_unlock(&xs->mutex);

        xskq_destroy(xs->rx);
        xskq_destroy(xs->tx);

        sock_orphan(sk);
        sock->sk = NULL;

        sk_refcnt_debug_release(sk);
        sock_put(sk);

        return 0;
}

static struct socket *xsk_lookup_xsk_from_fd(int fd)
{
        struct socket *sock;
        int err;

        sock = sockfd_lookup(fd, &err);
        if (!sock)
                return ERR_PTR(-ENOTSOCK);

        if (sock->sk->sk_family != PF_XDP) {
                sockfd_put(sock);
                return ERR_PTR(-ENOPROTOOPT);
        }

        return sock;
}

/* Check if umem pages are contiguous.
 * If zero-copy mode, use the DMA address to do the page contiguity check
 * For all other modes we use addr (kernel virtual address)
 * Store the result in the low bits of addr.
 */
static void xsk_check_page_contiguity(struct xdp_umem *umem, u32 flags)
{
        struct xdp_umem_page *pgs = umem->pages;
        int i, is_contig;

        for (i = 0; i < umem->npgs - 1; i++) {
                is_contig = (flags & XDP_ZEROCOPY) ?
                        (pgs[i].dma + PAGE_SIZE == pgs[i + 1].dma) :
                        (pgs[i].addr + PAGE_SIZE == pgs[i + 1].addr);
                pgs[i].addr += is_contig << XSK_NEXT_PG_CONTIG_SHIFT;
        }
}

static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
{
        struct sockaddr_xdp *sxdp = (struct sockaddr_xdp *)addr;
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);
        struct net_device *dev;
        u32 flags, qid;
        int err = 0;

        if (addr_len < sizeof(struct sockaddr_xdp))
                return -EINVAL;
        if (sxdp->sxdp_family != AF_XDP)
                return -EINVAL;

        flags = sxdp->sxdp_flags;
        if (flags & ~(XDP_SHARED_UMEM | XDP_COPY | XDP_ZEROCOPY |
                      XDP_USE_NEED_WAKEUP))
                return -EINVAL;

        rtnl_lock();
        mutex_lock(&xs->mutex);
        if (xs->state != XSK_READY) {
                err = -EBUSY;
                goto out_release;
        }

        dev = dev_get_by_index(sock_net(sk), sxdp->sxdp_ifindex);
        if (!dev) {
                err = -ENODEV;
                goto out_release;
        }

        if (!xs->rx && !xs->tx) {
                err = -EINVAL;
                goto out_unlock;
        }

        qid = sxdp->sxdp_queue_id;

        if (flags & XDP_SHARED_UMEM) {
                struct xdp_sock *umem_xs;
                struct socket *sock;

                if ((flags & XDP_COPY) || (flags & XDP_ZEROCOPY) ||
                    (flags & XDP_USE_NEED_WAKEUP)) {
                        /* Cannot specify flags for shared sockets. */
                        err = -EINVAL;
                        goto out_unlock;
                }

                if (xs->umem) {
                        /* We have already our own. */
                        err = -EINVAL;
                        goto out_unlock;
                }

                sock = xsk_lookup_xsk_from_fd(sxdp->sxdp_shared_umem_fd);
                if (IS_ERR(sock)) {
                        err = PTR_ERR(sock);
                        goto out_unlock;
                }

                umem_xs = xdp_sk(sock->sk);
                if (!xsk_is_bound(umem_xs)) {
                        err = -EBADF;
                        sockfd_put(sock);
                        goto out_unlock;
                }
                if (umem_xs->dev != dev || umem_xs->queue_id != qid) {
                        err = -EINVAL;
                        sockfd_put(sock);
                        goto out_unlock;
                }

                xdp_get_umem(umem_xs->umem);
                WRITE_ONCE(xs->umem, umem_xs->umem);
                sockfd_put(sock);
        } else if (!xs->umem || !xdp_umem_validate_queues(xs->umem)) {
                err = -EINVAL;
                goto out_unlock;
        } else {
                /* This xsk has its own umem. */
                xskq_set_umem(xs->umem->fq, xs->umem->size,
                              xs->umem->chunk_mask);
                xskq_set_umem(xs->umem->cq, xs->umem->size,
                              xs->umem->chunk_mask);

                err = xdp_umem_assign_dev(xs->umem, dev, qid, flags);
                if (err)
                        goto out_unlock;

                xsk_check_page_contiguity(xs->umem, flags);
        }

        xs->dev = dev;
        xs->zc = xs->umem->zc;
        xs->queue_id = qid;
        xskq_set_umem(xs->rx, xs->umem->size, xs->umem->chunk_mask);
        xskq_set_umem(xs->tx, xs->umem->size, xs->umem->chunk_mask);
        xdp_add_sk_umem(xs->umem, xs);

out_unlock:
        if (err) {
                dev_put(dev);
        } else {
                /* Matches smp_rmb() in bind() for shared umem
                 * sockets, and xsk_is_bound().
                 */
                smp_wmb();
                WRITE_ONCE(xs->state, XSK_BOUND);
        }
out_release:
        mutex_unlock(&xs->mutex);
        rtnl_unlock();
        return err;
}

struct xdp_umem_reg_v1 {
        __u64 addr; /* Start of packet data area */
        __u64 len; /* Length of packet data area */
        __u32 chunk_size;
        __u32 headroom;
};

static int xsk_setsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);
        int err;

        if (level != SOL_XDP)
                return -ENOPROTOOPT;

        switch (optname) {
        case XDP_RX_RING:
        case XDP_TX_RING:
        {
                struct xsk_queue **q;
                int entries;

                if (optlen < sizeof(entries))
                        return -EINVAL;
                if (copy_from_user(&entries, optval, sizeof(entries)))
                        return -EFAULT;

                mutex_lock(&xs->mutex);
                if (xs->state != XSK_READY) {
                        mutex_unlock(&xs->mutex);
                        return -EBUSY;
                }
                q = (optname == XDP_TX_RING) ? &xs->tx : &xs->rx;
                err = xsk_init_queue(entries, q, false);
                if (!err && optname == XDP_TX_RING)
                        /* Tx needs to be explicitly woken up the first time */
                        xs->tx->ring->flags |= XDP_RING_NEED_WAKEUP;
                mutex_unlock(&xs->mutex);
                return err;
        }
        case XDP_UMEM_REG:
        {
                size_t mr_size = sizeof(struct xdp_umem_reg);
                struct xdp_umem_reg mr = {};
                struct xdp_umem *umem;

                if (optlen < sizeof(struct xdp_umem_reg_v1))
                        return -EINVAL;
                else if (optlen < sizeof(mr))
                        mr_size = sizeof(struct xdp_umem_reg_v1);

                if (copy_from_user(&mr, optval, mr_size))
                        return -EFAULT;

                mutex_lock(&xs->mutex);
                if (xs->state != XSK_READY || xs->umem) {
                        mutex_unlock(&xs->mutex);
                        return -EBUSY;
                }

                umem = xdp_umem_create(&mr);
                if (IS_ERR(umem)) {
                        mutex_unlock(&xs->mutex);
                        return PTR_ERR(umem);
                }

                /* Make sure umem is ready before it can be seen by others */
                smp_wmb();
                WRITE_ONCE(xs->umem, umem);
                mutex_unlock(&xs->mutex);
                return 0;
        }
        case XDP_UMEM_FILL_RING:
        case XDP_UMEM_COMPLETION_RING:
        {
                struct xsk_queue **q;
                int entries;

                if (copy_from_user(&entries, optval, sizeof(entries)))
                        return -EFAULT;

                mutex_lock(&xs->mutex);
                if (xs->state != XSK_READY) {
                        mutex_unlock(&xs->mutex);
                        return -EBUSY;
                }
                if (!xs->umem) {
                        mutex_unlock(&xs->mutex);
                        return -EINVAL;
                }

                q = (optname == XDP_UMEM_FILL_RING) ? &xs->umem->fq :
                        &xs->umem->cq;
                err = xsk_init_queue(entries, q, true);
                mutex_unlock(&xs->mutex);
                return err;
        }
        default:
                break;
        }

        return -ENOPROTOOPT;
}

static void xsk_enter_rxtx_offsets(struct xdp_ring_offset_v1 *ring)
{
        ring->producer = offsetof(struct xdp_rxtx_ring, ptrs.producer);
        ring->consumer = offsetof(struct xdp_rxtx_ring, ptrs.consumer);
        ring->desc = offsetof(struct xdp_rxtx_ring, desc);
}

static void xsk_enter_umem_offsets(struct xdp_ring_offset_v1 *ring)
{
        ring->producer = offsetof(struct xdp_umem_ring, ptrs.producer);
        ring->consumer = offsetof(struct xdp_umem_ring, ptrs.consumer);
        ring->desc = offsetof(struct xdp_umem_ring, desc);
}

static int xsk_getsockopt(struct socket *sock, int level, int optname,
                          char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;
        struct xdp_sock *xs = xdp_sk(sk);
        int len;

        if (level != SOL_XDP)
                return -ENOPROTOOPT;

        if (get_user(len, optlen))
                return -EFAULT;
        if (len < 0)
                return -EINVAL;

        switch (optname) {
        case XDP_STATISTICS:
        {
                struct xdp_statistics stats;

                if (len < sizeof(stats))
                        return -EINVAL;

                mutex_lock(&xs->mutex);
                stats.rx_dropped = xs->rx_dropped;
                stats.rx_invalid_descs = xskq_nb_invalid_descs(xs->rx);
                stats.tx_invalid_descs = xskq_nb_invalid_descs(xs->tx);
                mutex_unlock(&xs->mutex);

                if (copy_to_user(optval, &stats, sizeof(stats)))
                        return -EFAULT;
                if (put_user(sizeof(stats), optlen))
                        return -EFAULT;

                return 0;
        }
        case XDP_MMAP_OFFSETS:
        {
                struct xdp_mmap_offsets off;
                struct xdp_mmap_offsets_v1 off_v1;
                bool flags_supported = true;
                void *to_copy;

                if (len < sizeof(off_v1))
                        return -EINVAL;
                else if (len < sizeof(off))
                        flags_supported = false;

                if (flags_supported) {
                        /* xdp_ring_offset is identical to xdp_ring_offset_v1
                         * except for the flags field added to the end.
                         */
                        xsk_enter_rxtx_offsets((struct xdp_ring_offset_v1 *)
                                               &off.rx);
                        xsk_enter_rxtx_offsets((struct xdp_ring_offset_v1 *)
                                               &off.tx);
                        xsk_enter_umem_offsets((struct xdp_ring_offset_v1 *)
                                               &off.fr);
                        xsk_enter_umem_offsets((struct xdp_ring_offset_v1 *)
                                               &off.cr);
                        off.rx.flags = offsetof(struct xdp_rxtx_ring,
                                                ptrs.flags);
                        off.tx.flags = offsetof(struct xdp_rxtx_ring,
                                                ptrs.flags);
                        off.fr.flags = offsetof(struct xdp_umem_ring,
                                                ptrs.flags);
                        off.cr.flags = offsetof(struct xdp_umem_ring,
                                                ptrs.flags);

                        len = sizeof(off);
                        to_copy = &off;
                } else {
                        xsk_enter_rxtx_offsets(&off_v1.rx);
                        xsk_enter_rxtx_offsets(&off_v1.tx);
                        xsk_enter_umem_offsets(&off_v1.fr);
                        xsk_enter_umem_offsets(&off_v1.cr);

                        len = sizeof(off_v1);
                        to_copy = &off_v1;
                }

                if (copy_to_user(optval, to_copy, len))
                        return -EFAULT;
                if (put_user(len, optlen))
                        return -EFAULT;

                return 0;
        }
        case XDP_OPTIONS:
        {
                struct xdp_options opts = {};

                if (len < sizeof(opts))
                        return -EINVAL;

                mutex_lock(&xs->mutex);
                if (xs->zc)
                        opts.flags |= XDP_OPTIONS_ZEROCOPY;
                mutex_unlock(&xs->mutex);

                len = sizeof(opts);
                if (copy_to_user(optval, &opts, len))
                        return -EFAULT;
                if (put_user(len, optlen))
                        return -EFAULT;

                return 0;
        }
        default:
                break;
        }

        return -EOPNOTSUPP;
}

static int xsk_mmap(struct file *file, struct socket *sock,
                    struct vm_area_struct *vma)
{
        loff_t offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
        unsigned long size = vma->vm_end - vma->vm_start;
        struct xdp_sock *xs = xdp_sk(sock->sk);
        struct xsk_queue *q = NULL;
        struct xdp_umem *umem;
        unsigned long pfn;
        struct page *qpg;

        if (READ_ONCE(xs->state) != XSK_READY)
                return -EBUSY;

        if (offset == XDP_PGOFF_RX_RING) {
                q = READ_ONCE(xs->rx);
        } else if (offset == XDP_PGOFF_TX_RING) {
                q = READ_ONCE(xs->tx);
        } else {
                umem = READ_ONCE(xs->umem);
                if (!umem)
                        return -EINVAL;

                /* Matches the smp_wmb() in XDP_UMEM_REG */
                smp_rmb();
                if (offset == XDP_UMEM_PGOFF_FILL_RING)
                        q = READ_ONCE(umem->fq);
                else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING)
                        q = READ_ONCE(umem->cq);
        }

        if (!q)
                return -EINVAL;

        /* Matches the smp_wmb() in xsk_init_queue */
        smp_rmb();
        qpg = virt_to_head_page(q->ring);
        if (size > page_size(qpg))
                return -EINVAL;

        pfn = virt_to_phys(q->ring) >> PAGE_SHIFT;
        return remap_pfn_range(vma, vma->vm_start, pfn,
                               size, vma->vm_page_prot);
}

static int xsk_notifier(struct notifier_block *this,
                        unsigned long msg, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        struct net *net = dev_net(dev);
        struct sock *sk;

        switch (msg) {
        case NETDEV_UNREGISTER:
                mutex_lock(&net->xdp.lock);
                sk_for_each(sk, &net->xdp.list) {
                        struct xdp_sock *xs = xdp_sk(sk);

                        mutex_lock(&xs->mutex);
                        if (xs->dev == dev) {
                                sk->sk_err = ENETDOWN;
                                if (!sock_flag(sk, SOCK_DEAD))
                                        sk->sk_error_report(sk);

                                xsk_unbind_dev(xs);

                                /* Clear device references in umem. */
                                xdp_umem_clear_dev(xs->umem);
                        }
                        mutex_unlock(&xs->mutex);
                }
                mutex_unlock(&net->xdp.lock);
                break;
        }
        return NOTIFY_DONE;
}

static struct proto xsk_proto = {
        .name =         "XDP",
        .owner =        THIS_MODULE,
        .obj_size =     sizeof(struct xdp_sock),
};

static const struct proto_ops xsk_proto_ops = {
        .family         = PF_XDP,
        .owner          = THIS_MODULE,
        .release        = xsk_release,
        .bind           = xsk_bind,
        .connect        = sock_no_connect,
        .socketpair     = sock_no_socketpair,
        .accept         = sock_no_accept,
        .getname        = sock_no_getname,
        .poll           = xsk_poll,
        .ioctl          = sock_no_ioctl,
        .listen         = sock_no_listen,
        .shutdown       = sock_no_shutdown,
        .setsockopt     = xsk_setsockopt,
        .getsockopt     = xsk_getsockopt,
        .sendmsg        = xsk_sendmsg,
        .recvmsg        = sock_no_recvmsg,
        .mmap           = xsk_mmap,
        .sendpage       = sock_no_sendpage,
};

static void xsk_destruct(struct sock *sk)
{
        struct xdp_sock *xs = xdp_sk(sk);

        if (!sock_flag(sk, SOCK_DEAD))
                return;

        xdp_put_umem(xs->umem);

        sk_refcnt_debug_dec(sk);
}

static int xsk_create(struct net *net, struct socket *sock, int protocol,
                      int kern)
{
        struct sock *sk;
        struct xdp_sock *xs;

        if (!ns_capable(net->user_ns, CAP_NET_RAW))
                return -EPERM;
        if (sock->type != SOCK_RAW)
                return -ESOCKTNOSUPPORT;

        if (protocol)
                return -EPROTONOSUPPORT;

        sock->state = SS_UNCONNECTED;

        sk = sk_alloc(net, PF_XDP, GFP_KERNEL, &xsk_proto, kern);
        if (!sk)
                return -ENOBUFS;

        sock->ops = &xsk_proto_ops;

        sock_init_data(sock, sk);

        sk->sk_family = PF_XDP;

        sk->sk_destruct = xsk_destruct;
        sk_refcnt_debug_inc(sk);

        sock_set_flag(sk, SOCK_RCU_FREE);

        xs = xdp_sk(sk);
        xs->state = XSK_READY;
        mutex_init(&xs->mutex);
        spin_lock_init(&xs->rx_lock);
        spin_lock_init(&xs->tx_completion_lock);

        INIT_LIST_HEAD(&xs->map_list);
        spin_lock_init(&xs->map_list_lock);

        mutex_lock(&net->xdp.lock);
        sk_add_node_rcu(sk, &net->xdp.list);
        mutex_unlock(&net->xdp.lock);

        local_bh_disable();
        sock_prot_inuse_add(net, &xsk_proto, 1);
        local_bh_enable();

        return 0;
}

static const struct net_proto_family xsk_family_ops = {
        .family = PF_XDP,
        .create = xsk_create,
        .owner  = THIS_MODULE,
};

static struct notifier_block xsk_netdev_notifier = {
        .notifier_call  = xsk_notifier,
};

static int __net_init xsk_net_init(struct net *net)
{
        mutex_init(&net->xdp.lock);
        INIT_HLIST_HEAD(&net->xdp.list);
        return 0;
}

static void __net_exit xsk_net_exit(struct net *net)
{
        WARN_ON_ONCE(!hlist_empty(&net->xdp.list));
}

static struct pernet_operations xsk_net_ops = {
        .init = xsk_net_init,
        .exit = xsk_net_exit,
};

static int __init xsk_init(void)
{
        int err, cpu;

        err = proto_register(&xsk_proto, 0 /* no slab */);
        if (err)
                goto out;

        err = sock_register(&xsk_family_ops);
        if (err)
                goto out_proto;

        err = register_pernet_subsys(&xsk_net_ops);
        if (err)
                goto out_sk;

        err = register_netdevice_notifier(&xsk_netdev_notifier);
        if (err)
                goto out_pernet;

        for_each_possible_cpu(cpu)
                INIT_LIST_HEAD(&per_cpu(xskmap_flush_list, cpu));
        return 0;

out_pernet:
        unregister_pernet_subsys(&xsk_net_ops);
out_sk:
        sock_unregister(PF_XDP);
out_proto:
        proto_unregister(&xsk_proto);
out:
        return err;
}

fs_initcall(xsk_init);