// SPDX-License-Identifier: GPL-2.0-only
/*
 * common code for virtio vsock
 *
 * Copyright (C) 2013-2015 Red Hat, Inc.
 * Author: Asias He <asias@redhat.com>
 *         Stefan Hajnoczi <stefanha@redhat.com>
 */
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/virtio_vsock.h>
#include <uapi/linux/vsockmon.h>

#include <net/sock.h>
#include <net/af_vsock.h>

#define CREATE_TRACE_POINTS
#include <trace/events/vsock_virtio_transport_common.h>

/* How long to wait for graceful shutdown of a connection */
#define VSOCK_CLOSE_TIMEOUT (8 * HZ)

/* Threshold for detecting small packets to copy */
#define GOOD_COPY_LEN  128

static const struct virtio_transport *
virtio_transport_get_ops(struct vsock_sock *vsk)
{
        const struct vsock_transport *t = vsock_core_get_transport(vsk);

        if (WARN_ON(!t))
                return NULL;

        return container_of(t, struct virtio_transport, transport);
}

static struct virtio_vsock_pkt *
virtio_transport_alloc_pkt(struct virtio_vsock_pkt_info *info,
                           size_t len,
                           u32 src_cid,
                           u32 src_port,
                           u32 dst_cid,
                           u32 dst_port)
{
        struct virtio_vsock_pkt *pkt;
        int err;

        pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
        if (!pkt)
                return NULL;

        pkt->hdr.type           = cpu_to_le16(info->type);
        pkt->hdr.op             = cpu_to_le16(info->op);
        pkt->hdr.src_cid        = cpu_to_le64(src_cid);
        pkt->hdr.dst_cid        = cpu_to_le64(dst_cid);
        pkt->hdr.src_port       = cpu_to_le32(src_port);
        pkt->hdr.dst_port       = cpu_to_le32(dst_port);
        pkt->hdr.flags          = cpu_to_le32(info->flags);
        pkt->len                = len;
        pkt->hdr.len            = cpu_to_le32(len);
        pkt->reply              = info->reply;
        pkt->vsk                = info->vsk;

        if (info->msg && len > 0) {
                pkt->buf = kmalloc(len, GFP_KERNEL);
                if (!pkt->buf)
                        goto out_pkt;

                pkt->buf_len = len;

                err = memcpy_from_msg(pkt->buf, info->msg, len);
                if (err)
                        goto out;

                if (msg_data_left(info->msg) == 0 &&
                    info->type == VIRTIO_VSOCK_TYPE_SEQPACKET) {
                        pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);

                        if (info->msg->msg_flags & MSG_EOR)
                                pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
                }
        }

        trace_virtio_transport_alloc_pkt(src_cid, src_port,
                                         dst_cid, dst_port,
                                         len,
                                         info->type,
                                         info->op,
                                         info->flags);

        return pkt;

out:
        kfree(pkt->buf);
out_pkt:
        kfree(pkt);
        return NULL;
}

/* Packet capture */
static struct sk_buff *virtio_transport_build_skb(void *opaque)
{
        struct virtio_vsock_pkt *pkt = opaque;
        struct af_vsockmon_hdr *hdr;
        struct sk_buff *skb;
        size_t payload_len;
        void *payload_buf;

        /* A packet could be split to fit the RX buffer, so we can retrieve
         * the payload length from the header and the buffer pointer taking
         * care of the offset in the original packet.
         */
        payload_len = le32_to_cpu(pkt->hdr.len);
        payload_buf = pkt->buf + pkt->off;

        skb = alloc_skb(sizeof(*hdr) + sizeof(pkt->hdr) + payload_len,
                        GFP_ATOMIC);
        if (!skb)
                return NULL;

        hdr = skb_put(skb, sizeof(*hdr));

        /* pkt->hdr is little-endian so no need to byteswap here */
        hdr->src_cid = pkt->hdr.src_cid;
        hdr->src_port = pkt->hdr.src_port;
        hdr->dst_cid = pkt->hdr.dst_cid;
        hdr->dst_port = pkt->hdr.dst_port;

        hdr->transport = cpu_to_le16(AF_VSOCK_TRANSPORT_VIRTIO);
        hdr->len = cpu_to_le16(sizeof(pkt->hdr));
        memset(hdr->reserved, 0, sizeof(hdr->reserved));

        switch (le16_to_cpu(pkt->hdr.op)) {
        case VIRTIO_VSOCK_OP_REQUEST:
        case VIRTIO_VSOCK_OP_RESPONSE:
                hdr->op = cpu_to_le16(AF_VSOCK_OP_CONNECT);
                break;
        case VIRTIO_VSOCK_OP_RST:
        case VIRTIO_VSOCK_OP_SHUTDOWN:
                hdr->op = cpu_to_le16(AF_VSOCK_OP_DISCONNECT);
                break;
        case VIRTIO_VSOCK_OP_RW:
                hdr->op = cpu_to_le16(AF_VSOCK_OP_PAYLOAD);
                break;
        case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
        case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
                hdr->op = cpu_to_le16(AF_VSOCK_OP_CONTROL);
                break;
        default:
                hdr->op = cpu_to_le16(AF_VSOCK_OP_UNKNOWN);
                break;
        }

        skb_put_data(skb, &pkt->hdr, sizeof(pkt->hdr));

        if (payload_len) {
                skb_put_data(skb, payload_buf, payload_len);
        }

        return skb;
}

void virtio_transport_deliver_tap_pkt(struct virtio_vsock_pkt *pkt)
{
        if (pkt->tap_delivered)
                return;

        vsock_deliver_tap(virtio_transport_build_skb, pkt);
        pkt->tap_delivered = true;
}
EXPORT_SYMBOL_GPL(virtio_transport_deliver_tap_pkt);

static u16 virtio_transport_get_type(struct sock *sk)
{
        if (sk->sk_type == SOCK_STREAM)
                return VIRTIO_VSOCK_TYPE_STREAM;
        else
                return VIRTIO_VSOCK_TYPE_SEQPACKET;
}

/* This function can only be used on connecting/connected sockets,
 * since a socket assigned to a transport is required.
 *
 * Do not use on listener sockets!
 */
static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
                                          struct virtio_vsock_pkt_info *info)
{
        u32 src_cid, src_port, dst_cid, dst_port;
        const struct virtio_transport *t_ops;
        struct virtio_vsock_sock *vvs;
        struct virtio_vsock_pkt *pkt;
        u32 pkt_len = info->pkt_len;

        info->type = virtio_transport_get_type(sk_vsock(vsk));

        t_ops = virtio_transport_get_ops(vsk);
        if (unlikely(!t_ops))
                return -EFAULT;

        src_cid = t_ops->transport.get_local_cid();
        src_port = vsk->local_addr.svm_port;
        if (!info->remote_cid) {
                dst_cid = vsk->remote_addr.svm_cid;
                dst_port = vsk->remote_addr.svm_port;
        } else {
                dst_cid = info->remote_cid;
                dst_port = info->remote_port;
        }

        vvs = vsk->trans;

        /* we can send less than pkt_len bytes */
        if (pkt_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
                pkt_len = VIRTIO_VSOCK_MAX_PKT_BUF_SIZE;

        /* virtio_transport_get_credit might return less than pkt_len credit */
        pkt_len = virtio_transport_get_credit(vvs, pkt_len);

        /* Do not send zero length OP_RW pkt */
        if (pkt_len == 0 && info->op == VIRTIO_VSOCK_OP_RW)
                return pkt_len;

        pkt = virtio_transport_alloc_pkt(info, pkt_len,
                                         src_cid, src_port,
                                         dst_cid, dst_port);
        if (!pkt) {
                virtio_transport_put_credit(vvs, pkt_len);
                return -ENOMEM;
        }

        virtio_transport_inc_tx_pkt(vvs, pkt);

        return t_ops->send_pkt(pkt);
}

static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
                                        struct virtio_vsock_pkt *pkt)
{
        if (vvs->rx_bytes + pkt->len > vvs->buf_alloc)
                return false;

        vvs->rx_bytes += pkt->len;
        return true;
}

static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
                                        struct virtio_vsock_pkt *pkt)
{
        vvs->rx_bytes -= pkt->len;
        vvs->fwd_cnt += pkt->len;
}

void virtio_transport_inc_tx_pkt(struct virtio_vsock_sock *vvs, struct virtio_vsock_pkt *pkt)
{
        spin_lock_bh(&vvs->rx_lock);
        vvs->last_fwd_cnt = vvs->fwd_cnt;
        pkt->hdr.fwd_cnt = cpu_to_le32(vvs->fwd_cnt);
        pkt->hdr.buf_alloc = cpu_to_le32(vvs->buf_alloc);
        spin_unlock_bh(&vvs->rx_lock);
}
EXPORT_SYMBOL_GPL(virtio_transport_inc_tx_pkt);

u32 virtio_transport_get_credit(struct virtio_vsock_sock *vvs, u32 credit)
{
        u32 ret;

        spin_lock_bh(&vvs->tx_lock);
        ret = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
        if (ret > credit)
                ret = credit;
        vvs->tx_cnt += ret;
        spin_unlock_bh(&vvs->tx_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(virtio_transport_get_credit);

void virtio_transport_put_credit(struct virtio_vsock_sock *vvs, u32 credit)
{
        spin_lock_bh(&vvs->tx_lock);
        vvs->tx_cnt -= credit;
        spin_unlock_bh(&vvs->tx_lock);
}
EXPORT_SYMBOL_GPL(virtio_transport_put_credit);

static int virtio_transport_send_credit_update(struct vsock_sock *vsk)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_CREDIT_UPDATE,
                .vsk = vsk,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
}

static ssize_t
virtio_transport_stream_do_peek(struct vsock_sock *vsk,
                                struct msghdr *msg,
                                size_t len)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        struct virtio_vsock_pkt *pkt;
        size_t bytes, total = 0, off;
        int err = -EFAULT;

        spin_lock_bh(&vvs->rx_lock);

        list_for_each_entry(pkt, &vvs->rx_queue, list) {
                off = pkt->off;

                if (total == len)
                        break;

                while (total < len && off < pkt->len) {
                        bytes = len - total;
                        if (bytes > pkt->len - off)
                                bytes = pkt->len - off;

                        /* sk_lock is held by caller so no one else can dequeue.
                         * Unlock rx_lock since memcpy_to_msg() may sleep.
                         */
                        spin_unlock_bh(&vvs->rx_lock);

                        err = memcpy_to_msg(msg, pkt->buf + off, bytes);
                        if (err)
                                goto out;

                        spin_lock_bh(&vvs->rx_lock);

                        total += bytes;
                        off += bytes;
                }
        }

        spin_unlock_bh(&vvs->rx_lock);

        return total;

out:
        if (total)
                err = total;
        return err;
}

static ssize_t
virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
                                   struct msghdr *msg,
                                   size_t len)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        struct virtio_vsock_pkt *pkt;
        size_t bytes, total = 0;
        u32 free_space;
        int err = -EFAULT;

        spin_lock_bh(&vvs->rx_lock);
        while (total < len && !list_empty(&vvs->rx_queue)) {
                pkt = list_first_entry(&vvs->rx_queue,
                                       struct virtio_vsock_pkt, list);

                bytes = len - total;
                if (bytes > pkt->len - pkt->off)
                        bytes = pkt->len - pkt->off;

                /* sk_lock is held by caller so no one else can dequeue.
                 * Unlock rx_lock since memcpy_to_msg() may sleep.
                 */
                spin_unlock_bh(&vvs->rx_lock);

                err = memcpy_to_msg(msg, pkt->buf + pkt->off, bytes);
                if (err)
                        goto out;

                spin_lock_bh(&vvs->rx_lock);

                total += bytes;
                pkt->off += bytes;
                if (pkt->off == pkt->len) {
                        virtio_transport_dec_rx_pkt(vvs, pkt);
                        list_del(&pkt->list);
                        virtio_transport_free_pkt(pkt);
                }
        }

        free_space = vvs->buf_alloc - (vvs->fwd_cnt - vvs->last_fwd_cnt);

        spin_unlock_bh(&vvs->rx_lock);

        /* To reduce the number of credit update messages,
         * don't update credits as long as lots of space is available.
         * Note: the limit chosen here is arbitrary. Setting the limit
         * too high causes extra messages. Too low causes transmitter
         * stalls. As stalls are in theory more expensive than extra
         * messages, we set the limit to a high value. TODO: experiment
         * with different values.
         */
        if (free_space < VIRTIO_VSOCK_MAX_PKT_BUF_SIZE)
                virtio_transport_send_credit_update(vsk);

        return total;

out:
        if (total)
                err = total;
        return err;
}

static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
                                                 struct msghdr *msg,
                                                 int flags)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        struct virtio_vsock_pkt *pkt;
        int dequeued_len = 0;
        size_t user_buf_len = msg_data_left(msg);
        bool msg_ready = false;

        spin_lock_bh(&vvs->rx_lock);

        if (vvs->msg_count == 0) {
                spin_unlock_bh(&vvs->rx_lock);
                return 0;
        }

        while (!msg_ready) {
                pkt = list_first_entry(&vvs->rx_queue, struct virtio_vsock_pkt, list);

                if (dequeued_len >= 0) {
                        size_t pkt_len;
                        size_t bytes_to_copy;

                        pkt_len = (size_t)le32_to_cpu(pkt->hdr.len);
                        bytes_to_copy = min(user_buf_len, pkt_len);

                        if (bytes_to_copy) {
                                int err;

                                /* sk_lock is held by caller so no one else can dequeue.
                                 * Unlock rx_lock since memcpy_to_msg() may sleep.
                                 */
                                spin_unlock_bh(&vvs->rx_lock);

                                err = memcpy_to_msg(msg, pkt->buf, bytes_to_copy);
                                if (err) {
                                        /* Copy of message failed. Rest of
                                         * fragments will be freed without copy.
                                         */
                                        dequeued_len = err;
                                } else {
                                        user_buf_len -= bytes_to_copy;
                                }

                                spin_lock_bh(&vvs->rx_lock);
                        }

                        if (dequeued_len >= 0)
                                dequeued_len += pkt_len;
                }

                if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
                        msg_ready = true;
                        vvs->msg_count--;

                        if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOR)
                                msg->msg_flags |= MSG_EOR;
                }

                virtio_transport_dec_rx_pkt(vvs, pkt);
                list_del(&pkt->list);
                virtio_transport_free_pkt(pkt);
        }

        spin_unlock_bh(&vvs->rx_lock);

        virtio_transport_send_credit_update(vsk);

        return dequeued_len;
}

ssize_t
virtio_transport_stream_dequeue(struct vsock_sock *vsk,
                                struct msghdr *msg,
                                size_t len, int flags)
{
        if (flags & MSG_PEEK)
                return virtio_transport_stream_do_peek(vsk, msg, len);
        else
                return virtio_transport_stream_do_dequeue(vsk, msg, len);
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_dequeue);

ssize_t
virtio_transport_seqpacket_dequeue(struct vsock_sock *vsk,
                                   struct msghdr *msg,
                                   int flags)
{
        if (flags & MSG_PEEK)
                return -EOPNOTSUPP;

        return virtio_transport_seqpacket_do_dequeue(vsk, msg, flags);
}
EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_dequeue);

int
virtio_transport_seqpacket_enqueue(struct vsock_sock *vsk,
                                   struct msghdr *msg,
                                   size_t len)
{
        struct virtio_vsock_sock *vvs = vsk->trans;

        spin_lock_bh(&vvs->tx_lock);

        if (len > vvs->peer_buf_alloc) {
                spin_unlock_bh(&vvs->tx_lock);
                return -EMSGSIZE;
        }

        spin_unlock_bh(&vvs->tx_lock);

        return virtio_transport_stream_enqueue(vsk, msg, len);
}
EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_enqueue);

int
virtio_transport_dgram_dequeue(struct vsock_sock *vsk,
                               struct msghdr *msg,
                               size_t len, int flags)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_dequeue);

s64 virtio_transport_stream_has_data(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        s64 bytes;

        spin_lock_bh(&vvs->rx_lock);
        bytes = vvs->rx_bytes;
        spin_unlock_bh(&vvs->rx_lock);

        return bytes;
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_has_data);

u32 virtio_transport_seqpacket_has_data(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        u32 msg_count;

        spin_lock_bh(&vvs->rx_lock);
        msg_count = vvs->msg_count;
        spin_unlock_bh(&vvs->rx_lock);

        return msg_count;
}
EXPORT_SYMBOL_GPL(virtio_transport_seqpacket_has_data);

static s64 virtio_transport_has_space(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        s64 bytes;

        bytes = vvs->peer_buf_alloc - (vvs->tx_cnt - vvs->peer_fwd_cnt);
        if (bytes < 0)
                bytes = 0;

        return bytes;
}

s64 virtio_transport_stream_has_space(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        s64 bytes;

        spin_lock_bh(&vvs->tx_lock);
        bytes = virtio_transport_has_space(vsk);
        spin_unlock_bh(&vvs->tx_lock);

        return bytes;
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_has_space);

int virtio_transport_do_socket_init(struct vsock_sock *vsk,
                                    struct vsock_sock *psk)
{
        struct virtio_vsock_sock *vvs;

        vvs = kzalloc(sizeof(*vvs), GFP_KERNEL);
        if (!vvs)
                return -ENOMEM;

        vsk->trans = vvs;
        vvs->vsk = vsk;
        if (psk && psk->trans) {
                struct virtio_vsock_sock *ptrans = psk->trans;

                vvs->peer_buf_alloc = ptrans->peer_buf_alloc;
        }

        if (vsk->buffer_size > VIRTIO_VSOCK_MAX_BUF_SIZE)
                vsk->buffer_size = VIRTIO_VSOCK_MAX_BUF_SIZE;

        vvs->buf_alloc = vsk->buffer_size;

        spin_lock_init(&vvs->rx_lock);
        spin_lock_init(&vvs->tx_lock);
        INIT_LIST_HEAD(&vvs->rx_queue);

        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_do_socket_init);

/* sk_lock held by the caller */
void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val)
{
        struct virtio_vsock_sock *vvs = vsk->trans;

        if (*val > VIRTIO_VSOCK_MAX_BUF_SIZE)
                *val = VIRTIO_VSOCK_MAX_BUF_SIZE;

        vvs->buf_alloc = *val;

        virtio_transport_send_credit_update(vsk);
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_buffer_size);

int
virtio_transport_notify_poll_in(struct vsock_sock *vsk,
                                size_t target,
                                bool *data_ready_now)
{
        if (vsock_stream_has_data(vsk))
                *data_ready_now = true;
        else
                *data_ready_now = false;

        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_in);

int
virtio_transport_notify_poll_out(struct vsock_sock *vsk,
                                 size_t target,
                                 bool *space_avail_now)
{
        s64 free_space;

        free_space = vsock_stream_has_space(vsk);
        if (free_space > 0)
                *space_avail_now = true;
        else if (free_space == 0)
                *space_avail_now = false;

        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_poll_out);

int virtio_transport_notify_recv_init(struct vsock_sock *vsk,
        size_t target, struct vsock_transport_recv_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_init);

int virtio_transport_notify_recv_pre_block(struct vsock_sock *vsk,
        size_t target, struct vsock_transport_recv_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_block);

int virtio_transport_notify_recv_pre_dequeue(struct vsock_sock *vsk,
        size_t target, struct vsock_transport_recv_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_pre_dequeue);

int virtio_transport_notify_recv_post_dequeue(struct vsock_sock *vsk,
        size_t target, ssize_t copied, bool data_read,
        struct vsock_transport_recv_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_recv_post_dequeue);

int virtio_transport_notify_send_init(struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_send_init);

int virtio_transport_notify_send_pre_block(struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_block);

int virtio_transport_notify_send_pre_enqueue(struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_send_pre_enqueue);

int virtio_transport_notify_send_post_enqueue(struct vsock_sock *vsk,
        ssize_t written, struct vsock_transport_send_notify_data *data)
{
        return 0;
}
EXPORT_SYMBOL_GPL(virtio_transport_notify_send_post_enqueue);

u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk)
{
        return vsk->buffer_size;
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_rcvhiwat);

bool virtio_transport_stream_is_active(struct vsock_sock *vsk)
{
        return true;
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_is_active);

bool virtio_transport_stream_allow(u32 cid, u32 port)
{
        return true;
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_allow);

int virtio_transport_dgram_bind(struct vsock_sock *vsk,
                                struct sockaddr_vm *addr)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind);

bool virtio_transport_dgram_allow(u32 cid, u32 port)
{
        return false;
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_allow);

int virtio_transport_connect(struct vsock_sock *vsk)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_REQUEST,
                .vsk = vsk,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
}
EXPORT_SYMBOL_GPL(virtio_transport_connect);

int virtio_transport_shutdown(struct vsock_sock *vsk, int mode)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_SHUTDOWN,
                .flags = (mode & RCV_SHUTDOWN ?
                          VIRTIO_VSOCK_SHUTDOWN_RCV : 0) |
                         (mode & SEND_SHUTDOWN ?
                          VIRTIO_VSOCK_SHUTDOWN_SEND : 0),
                .vsk = vsk,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
}
EXPORT_SYMBOL_GPL(virtio_transport_shutdown);

int
virtio_transport_dgram_enqueue(struct vsock_sock *vsk,
                               struct sockaddr_vm *remote_addr,
                               struct msghdr *msg,
                               size_t dgram_len)
{
        return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(virtio_transport_dgram_enqueue);

ssize_t
virtio_transport_stream_enqueue(struct vsock_sock *vsk,
                                struct msghdr *msg,
                                size_t len)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_RW,
                .msg = msg,
                .pkt_len = len,
                .vsk = vsk,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
}
EXPORT_SYMBOL_GPL(virtio_transport_stream_enqueue);

void virtio_transport_destruct(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;

        kfree(vvs);
}
EXPORT_SYMBOL_GPL(virtio_transport_destruct);

static int virtio_transport_reset(struct vsock_sock *vsk,
                                  struct virtio_vsock_pkt *pkt)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_RST,
                .reply = !!pkt,
                .vsk = vsk,
        };

        /* Send RST only if the original pkt is not a RST pkt */
        if (pkt && le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
                return 0;

        return virtio_transport_send_pkt_info(vsk, &info);
}

/* Normally packets are associated with a socket.  There may be no socket if an
 * attempt was made to connect to a socket that does not exist.
 */
static int virtio_transport_reset_no_sock(const struct virtio_transport *t,
                                          struct virtio_vsock_pkt *pkt)
{
        struct virtio_vsock_pkt *reply;
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_RST,
                .type = le16_to_cpu(pkt->hdr.type),
                .reply = true,
        };

        /* Send RST only if the original pkt is not a RST pkt */
        if (le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
                return 0;

        reply = virtio_transport_alloc_pkt(&info, 0,
                                           le64_to_cpu(pkt->hdr.dst_cid),
                                           le32_to_cpu(pkt->hdr.dst_port),
                                           le64_to_cpu(pkt->hdr.src_cid),
                                           le32_to_cpu(pkt->hdr.src_port));
        if (!reply)
                return -ENOMEM;

        if (!t) {
                virtio_transport_free_pkt(reply);
                return -ENOTCONN;
        }

        return t->send_pkt(reply);
}

/* This function should be called with sk_lock held and SOCK_DONE set */
static void virtio_transport_remove_sock(struct vsock_sock *vsk)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        struct virtio_vsock_pkt *pkt, *tmp;

        /* We don't need to take rx_lock, as the socket is closing and we are
         * removing it.
         */
        list_for_each_entry_safe(pkt, tmp, &vvs->rx_queue, list) {
                list_del(&pkt->list);
                virtio_transport_free_pkt(pkt);
        }

        vsock_remove_sock(vsk);
}

static void virtio_transport_wait_close(struct sock *sk, long timeout)
{
        if (timeout) {
                DEFINE_WAIT_FUNC(wait, woken_wake_function);

                add_wait_queue(sk_sleep(sk), &wait);

                do {
                        if (sk_wait_event(sk, &timeout,
                                          sock_flag(sk, SOCK_DONE), &wait))
                                break;
                } while (!signal_pending(current) && timeout);

                remove_wait_queue(sk_sleep(sk), &wait);
        }
}

static void virtio_transport_do_close(struct vsock_sock *vsk,
                                      bool cancel_timeout)
{
        struct sock *sk = sk_vsock(vsk);

        sock_set_flag(sk, SOCK_DONE);
        vsk->peer_shutdown = SHUTDOWN_MASK;
        if (vsock_stream_has_data(vsk) <= 0)
                sk->sk_state = TCP_CLOSING;
        sk->sk_state_change(sk);

        if (vsk->close_work_scheduled &&
            (!cancel_timeout || cancel_delayed_work(&vsk->close_work))) {
                vsk->close_work_scheduled = false;

                virtio_transport_remove_sock(vsk);

                /* Release refcnt obtained when we scheduled the timeout */
                sock_put(sk);
        }
}

static void virtio_transport_close_timeout(struct work_struct *work)
{
        struct vsock_sock *vsk =
                container_of(work, struct vsock_sock, close_work.work);
        struct sock *sk = sk_vsock(vsk);

        sock_hold(sk);
        lock_sock(sk);

        if (!sock_flag(sk, SOCK_DONE)) {
                (void)virtio_transport_reset(vsk, NULL);

                virtio_transport_do_close(vsk, false);
        }

        vsk->close_work_scheduled = false;

        release_sock(sk);
        sock_put(sk);
}

/* User context, vsk->sk is locked */
static bool virtio_transport_close(struct vsock_sock *vsk)
{
        struct sock *sk = &vsk->sk;

        if (!(sk->sk_state == TCP_ESTABLISHED ||
              sk->sk_state == TCP_CLOSING))
                return true;

        /* Already received SHUTDOWN from peer, reply with RST */
        if ((vsk->peer_shutdown & SHUTDOWN_MASK) == SHUTDOWN_MASK) {
                (void)virtio_transport_reset(vsk, NULL);
                return true;
        }

        if ((sk->sk_shutdown & SHUTDOWN_MASK) != SHUTDOWN_MASK)
                (void)virtio_transport_shutdown(vsk, SHUTDOWN_MASK);

        if (sock_flag(sk, SOCK_LINGER) && !(current->flags & PF_EXITING))
                virtio_transport_wait_close(sk, sk->sk_lingertime);

        if (sock_flag(sk, SOCK_DONE)) {
                return true;
        }

        sock_hold(sk);
        INIT_DELAYED_WORK(&vsk->close_work,
                          virtio_transport_close_timeout);
        vsk->close_work_scheduled = true;
        schedule_delayed_work(&vsk->close_work, VSOCK_CLOSE_TIMEOUT);
        return false;
}

void virtio_transport_release(struct vsock_sock *vsk)
{
        struct sock *sk = &vsk->sk;
        bool remove_sock = true;

        if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)
                remove_sock = virtio_transport_close(vsk);

        if (remove_sock) {
                sock_set_flag(sk, SOCK_DONE);
                virtio_transport_remove_sock(vsk);
        }
}
EXPORT_SYMBOL_GPL(virtio_transport_release);

static int
virtio_transport_recv_connecting(struct sock *sk,
                                 struct virtio_vsock_pkt *pkt)
{
        struct vsock_sock *vsk = vsock_sk(sk);
        int err;
        int skerr;

        switch (le16_to_cpu(pkt->hdr.op)) {
        case VIRTIO_VSOCK_OP_RESPONSE:
                sk->sk_state = TCP_ESTABLISHED;
                sk->sk_socket->state = SS_CONNECTED;
                vsock_insert_connected(vsk);
                sk->sk_state_change(sk);
                break;
        case VIRTIO_VSOCK_OP_INVALID:

                break;
        case VIRTIO_VSOCK_OP_RST:
                skerr = ECONNRESET;
                err = 0;
                goto destroy;
        default:
                skerr = EPROTO;
                err = -EINVAL;
                goto destroy;
        }
        return 0;

destroy:
        virtio_transport_reset(vsk, pkt);
        sk->sk_state = TCP_CLOSE;
        sk->sk_err = skerr;
        sk_error_report(sk);
        return err;
}

static void
virtio_transport_recv_enqueue(struct vsock_sock *vsk,
                              struct virtio_vsock_pkt *pkt)
{
        struct virtio_vsock_sock *vvs = vsk->trans;
        bool can_enqueue, free_pkt = false;

        pkt->len = le32_to_cpu(pkt->hdr.len);
        pkt->off = 0;

        spin_lock_bh(&vvs->rx_lock);

        can_enqueue = virtio_transport_inc_rx_pkt(vvs, pkt);
        if (!can_enqueue) {
                free_pkt = true;
                goto out;
        }

        if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)
                vvs->msg_count++;

        /* Try to copy small packets into the buffer of last packet queued,
         * to avoid wasting memory queueing the entire buffer with a small
         * payload.
         */
        if (pkt->len <= GOOD_COPY_LEN && !list_empty(&vvs->rx_queue)) {
                struct virtio_vsock_pkt *last_pkt;

                last_pkt = list_last_entry(&vvs->rx_queue,
                                           struct virtio_vsock_pkt, list);

                /* If there is space in the last packet queued, we copy the
                 * new packet in its buffer. We avoid this if the last packet
                 * queued has VIRTIO_VSOCK_SEQ_EOM set, because this is
                 * delimiter of SEQPACKET message, so 'pkt' is the first packet
                 * of a new message.
                 */
                if ((pkt->len <= last_pkt->buf_len - last_pkt->len) &&
                    !(le32_to_cpu(last_pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM)) {
                        memcpy(last_pkt->buf + last_pkt->len, pkt->buf,
                               pkt->len);
                        last_pkt->len += pkt->len;
                        free_pkt = true;
                        last_pkt->hdr.flags |= pkt->hdr.flags;
                        goto out;
                }
        }

        list_add_tail(&pkt->list, &vvs->rx_queue);

out:
        spin_unlock_bh(&vvs->rx_lock);
        if (free_pkt)
                virtio_transport_free_pkt(pkt);
}

static int
virtio_transport_recv_connected(struct sock *sk,
                                struct virtio_vsock_pkt *pkt)
{
        struct vsock_sock *vsk = vsock_sk(sk);
        int err = 0;

        switch (le16_to_cpu(pkt->hdr.op)) {
        case VIRTIO_VSOCK_OP_RW:
                virtio_transport_recv_enqueue(vsk, pkt);
                sk->sk_data_ready(sk);
                return err;
        case VIRTIO_VSOCK_OP_CREDIT_REQUEST:
                virtio_transport_send_credit_update(vsk);
                break;
        case VIRTIO_VSOCK_OP_CREDIT_UPDATE:
                sk->sk_write_space(sk);
                break;
        case VIRTIO_VSOCK_OP_SHUTDOWN:
                if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SHUTDOWN_RCV)
                        vsk->peer_shutdown |= RCV_SHUTDOWN;
                if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SHUTDOWN_SEND)
                        vsk->peer_shutdown |= SEND_SHUTDOWN;
                if (vsk->peer_shutdown == SHUTDOWN_MASK &&
                    vsock_stream_has_data(vsk) <= 0 &&
                    !sock_flag(sk, SOCK_DONE)) {
                        (void)virtio_transport_reset(vsk, NULL);

                        virtio_transport_do_close(vsk, true);
                }
                if (le32_to_cpu(pkt->hdr.flags))
                        sk->sk_state_change(sk);
                break;
        case VIRTIO_VSOCK_OP_RST:
                virtio_transport_do_close(vsk, true);
                break;
        default:
                err = -EINVAL;
                break;
        }

        virtio_transport_free_pkt(pkt);
        return err;
}

static void
virtio_transport_recv_disconnecting(struct sock *sk,
                                    struct virtio_vsock_pkt *pkt)
{
        struct vsock_sock *vsk = vsock_sk(sk);

        if (le16_to_cpu(pkt->hdr.op) == VIRTIO_VSOCK_OP_RST)
                virtio_transport_do_close(vsk, true);
}

static int
virtio_transport_send_response(struct vsock_sock *vsk,
                               struct virtio_vsock_pkt *pkt)
{
        struct virtio_vsock_pkt_info info = {
                .op = VIRTIO_VSOCK_OP_RESPONSE,
                .remote_cid = le64_to_cpu(pkt->hdr.src_cid),
                .remote_port = le32_to_cpu(pkt->hdr.src_port),
                .reply = true,
                .vsk = vsk,
        };

        return virtio_transport_send_pkt_info(vsk, &info);
}

static bool virtio_transport_space_update(struct sock *sk,
                                          struct virtio_vsock_pkt *pkt)
{
        struct vsock_sock *vsk = vsock_sk(sk);
        struct virtio_vsock_sock *vvs = vsk->trans;
        bool space_available;

        /* Listener sockets are not associated with any transport, so we are
         * not able to take the state to see if there is space available in the
         * remote peer, but since they are only used to receive requests, we
         * can assume that there is always space available in the other peer.
         */
        if (!vvs)
                return true;

        /* buf_alloc and fwd_cnt is always included in the hdr */
        spin_lock_bh(&vvs->tx_lock);
        vvs->peer_buf_alloc = le32_to_cpu(pkt->hdr.buf_alloc);
        vvs->peer_fwd_cnt = le32_to_cpu(pkt->hdr.fwd_cnt);
        space_available = virtio_transport_has_space(vsk);
        spin_unlock_bh(&vvs->tx_lock);
        return space_available;
}

/* Handle server socket */
static int
virtio_transport_recv_listen(struct sock *sk, struct virtio_vsock_pkt *pkt,
                             struct virtio_transport *t)
{
        struct vsock_sock *vsk = vsock_sk(sk);
        struct vsock_sock *vchild;
        struct sock *child;
        int ret;

        if (le16_to_cpu(pkt->hdr.op) != VIRTIO_VSOCK_OP_REQUEST) {
                virtio_transport_reset_no_sock(t, pkt);
                return -EINVAL;
        }

        if (sk_acceptq_is_full(sk)) {
                virtio_transport_reset_no_sock(t, pkt);
                return -ENOMEM;
        }

        child = vsock_create_connected(sk);
        if (!child) {
                virtio_transport_reset_no_sock(t, pkt);
                return -ENOMEM;
        }

        sk_acceptq_added(sk);

        lock_sock_nested(child, SINGLE_DEPTH_NESTING);

        child->sk_state = TCP_ESTABLISHED;

        vchild = vsock_sk(child);
        vsock_addr_init(&vchild->local_addr, le64_to_cpu(pkt->hdr.dst_cid),
                        le32_to_cpu(pkt->hdr.dst_port));
        vsock_addr_init(&vchild->remote_addr, le64_to_cpu(pkt->hdr.src_cid),
                        le32_to_cpu(pkt->hdr.src_port));

        ret = vsock_assign_transport(vchild, vsk);
        /* Transport assigned (looking at remote_addr) must be the same
         * where we received the request.
         */
        if (ret || vchild->transport != &t->transport) {
                release_sock(child);
                virtio_transport_reset_no_sock(t, pkt);
                sock_put(child);
                return ret;
        }

        if (virtio_transport_space_update(child, pkt))
                child->sk_write_space(child);

        vsock_insert_connected(vchild);
        vsock_enqueue_accept(sk, child);
        virtio_transport_send_response(vchild, pkt);

        release_sock(child);

        sk->sk_data_ready(sk);
        return 0;
}

static bool virtio_transport_valid_type(u16 type)
{
        return (type == VIRTIO_VSOCK_TYPE_STREAM) ||
               (type == VIRTIO_VSOCK_TYPE_SEQPACKET);
}

/* We are under the virtio-vsock's vsock->rx_lock or vhost-vsock's vq->mutex
 * lock.
 */
void virtio_transport_recv_pkt(struct virtio_transport *t,
                               struct virtio_vsock_pkt *pkt)
{
        struct sockaddr_vm src, dst;
        struct vsock_sock *vsk;
        struct sock *sk;
        bool space_available;

        vsock_addr_init(&src, le64_to_cpu(pkt->hdr.src_cid),
                        le32_to_cpu(pkt->hdr.src_port));
        vsock_addr_init(&dst, le64_to_cpu(pkt->hdr.dst_cid),
                        le32_to_cpu(pkt->hdr.dst_port));

        trace_virtio_transport_recv_pkt(src.svm_cid, src.svm_port,
                                        dst.svm_cid, dst.svm_port,
                                        le32_to_cpu(pkt->hdr.len),
                                        le16_to_cpu(pkt->hdr.type),
                                        le16_to_cpu(pkt->hdr.op),
                                        le32_to_cpu(pkt->hdr.flags),
                                        le32_to_cpu(pkt->hdr.buf_alloc),
                                        le32_to_cpu(pkt->hdr.fwd_cnt));

        if (!virtio_transport_valid_type(le16_to_cpu(pkt->hdr.type))) {
                (void)virtio_transport_reset_no_sock(t, pkt);
                goto free_pkt;
        }

        /* The socket must be in connected or bound table
         * otherwise send reset back
         */
        sk = vsock_find_connected_socket(&src, &dst);
        if (!sk) {
                sk = vsock_find_bound_socket(&dst);
                if (!sk) {
                        (void)virtio_transport_reset_no_sock(t, pkt);
                        goto free_pkt;
                }
        }

        if (virtio_transport_get_type(sk) != le16_to_cpu(pkt->hdr.type)) {
                (void)virtio_transport_reset_no_sock(t, pkt);
                sock_put(sk);
                goto free_pkt;
        }

        vsk = vsock_sk(sk);

        lock_sock(sk);

        /* Check if sk has been closed before lock_sock */
        if (sock_flag(sk, SOCK_DONE)) {
                (void)virtio_transport_reset_no_sock(t, pkt);
                release_sock(sk);
                sock_put(sk);
                goto free_pkt;
        }

        space_available = virtio_transport_space_update(sk, pkt);

        /* Update CID in case it has changed after a transport reset event */
        if (vsk->local_addr.svm_cid != VMADDR_CID_ANY)
                vsk->local_addr.svm_cid = dst.svm_cid;

        if (space_available)
                sk->sk_write_space(sk);

        switch (sk->sk_state) {
        case TCP_LISTEN:
                virtio_transport_recv_listen(sk, pkt, t);
                virtio_transport_free_pkt(pkt);
                break;
        case TCP_SYN_SENT:
                virtio_transport_recv_connecting(sk, pkt);
                virtio_transport_free_pkt(pkt);
                break;
        case TCP_ESTABLISHED:
                virtio_transport_recv_connected(sk, pkt);
                break;
        case TCP_CLOSING:
                virtio_transport_recv_disconnecting(sk, pkt);
                virtio_transport_free_pkt(pkt);
                break;
        default:
                (void)virtio_transport_reset_no_sock(t, pkt);
                virtio_transport_free_pkt(pkt);
                break;
        }

        release_sock(sk);

        /* Release refcnt obtained when we fetched this socket out of the
         * bound or connected list.
         */
        sock_put(sk);
        return;

free_pkt:
        virtio_transport_free_pkt(pkt);
}
EXPORT_SYMBOL_GPL(virtio_transport_recv_pkt);

void virtio_transport_free_pkt(struct virtio_vsock_pkt *pkt)
{
        kfree(pkt->buf);
        kfree(pkt);
}
EXPORT_SYMBOL_GPL(virtio_transport_free_pkt);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Asias He");
MODULE_DESCRIPTION("common code for virtio vsock");