// SPDX-License-Identifier: GPL-2.0-only
/*
 * VMware vSockets Driver
 *
 * Copyright (C) 2007-2013 VMware, Inc. All rights reserved.
 */

#include <linux/types.h>
#include <linux/bitops.h>
#include <linux/cred.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/net.h>
#include <linux/poll.h>
#include <linux/skbuff.h>
#include <linux/smp.h>
#include <linux/socket.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <net/sock.h>
#include <net/af_vsock.h>

#include "vmci_transport_notify.h"

static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg);
static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg);
static void vmci_transport_peer_detach_cb(u32 sub_id,
                                          const struct vmci_event_data *ed,
                                          void *client_data);
static void vmci_transport_recv_pkt_work(struct work_struct *work);
static void vmci_transport_cleanup(struct work_struct *work);
static int vmci_transport_recv_listen(struct sock *sk,
                                      struct vmci_transport_packet *pkt);
static int vmci_transport_recv_connecting_server(
                                        struct sock *sk,
                                        struct sock *pending,
                                        struct vmci_transport_packet *pkt);
static int vmci_transport_recv_connecting_client(
                                        struct sock *sk,
                                        struct vmci_transport_packet *pkt);
static int vmci_transport_recv_connecting_client_negotiate(
                                        struct sock *sk,
                                        struct vmci_transport_packet *pkt);
static int vmci_transport_recv_connecting_client_invalid(
                                        struct sock *sk,
                                        struct vmci_transport_packet *pkt);
static int vmci_transport_recv_connected(struct sock *sk,
                                         struct vmci_transport_packet *pkt);
static bool vmci_transport_old_proto_override(bool *old_pkt_proto);
static u16 vmci_transport_new_proto_supported_versions(void);
static bool vmci_transport_proto_to_notify_struct(struct sock *sk, u16 *proto,
                                                  bool old_pkt_proto);

struct vmci_transport_recv_pkt_info {
        struct work_struct work;
        struct sock *sk;
        struct vmci_transport_packet pkt;
};

static LIST_HEAD(vmci_transport_cleanup_list);
static DEFINE_SPINLOCK(vmci_transport_cleanup_lock);
static DECLARE_WORK(vmci_transport_cleanup_work, vmci_transport_cleanup);

static struct vmci_handle vmci_transport_stream_handle = { VMCI_INVALID_ID,
                                                           VMCI_INVALID_ID };
static u32 vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;

static int PROTOCOL_OVERRIDE = -1;

#define VMCI_TRANSPORT_DEFAULT_QP_SIZE_MIN   128
#define VMCI_TRANSPORT_DEFAULT_QP_SIZE       262144
#define VMCI_TRANSPORT_DEFAULT_QP_SIZE_MAX   262144

/* The default peer timeout indicates how long we will wait for a peer response
 * to a control message.
 */
#define VSOCK_DEFAULT_CONNECT_TIMEOUT (2 * HZ)

/* Helper function to convert from a VMCI error code to a VSock error code. */

static s32 vmci_transport_error_to_vsock_error(s32 vmci_error)
{
        switch (vmci_error) {
        case VMCI_ERROR_NO_MEM:
                return -ENOMEM;
        case VMCI_ERROR_DUPLICATE_ENTRY:
        case VMCI_ERROR_ALREADY_EXISTS:
                return -EADDRINUSE;
        case VMCI_ERROR_NO_ACCESS:
                return -EPERM;
        case VMCI_ERROR_NO_RESOURCES:
                return -ENOBUFS;
        case VMCI_ERROR_INVALID_RESOURCE:
                return -EHOSTUNREACH;
        case VMCI_ERROR_INVALID_ARGS:
        default:
                break;
        }
        return -EINVAL;
}

static u32 vmci_transport_peer_rid(u32 peer_cid)
{
        if (VMADDR_CID_HYPERVISOR == peer_cid)
                return VMCI_TRANSPORT_HYPERVISOR_PACKET_RID;

        return VMCI_TRANSPORT_PACKET_RID;
}

static inline void
vmci_transport_packet_init(struct vmci_transport_packet *pkt,
                           struct sockaddr_vm *src,
                           struct sockaddr_vm *dst,
                           u8 type,
                           u64 size,
                           u64 mode,
                           struct vmci_transport_waiting_info *wait,
                           u16 proto,
                           struct vmci_handle handle)
{
        /* We register the stream control handler as an any cid handle so we
         * must always send from a source address of VMADDR_CID_ANY
         */
        pkt->dg.src = vmci_make_handle(VMADDR_CID_ANY,
                                       VMCI_TRANSPORT_PACKET_RID);
        pkt->dg.dst = vmci_make_handle(dst->svm_cid,
                                       vmci_transport_peer_rid(dst->svm_cid));
        pkt->dg.payload_size = sizeof(*pkt) - sizeof(pkt->dg);
        pkt->version = VMCI_TRANSPORT_PACKET_VERSION;
        pkt->type = type;
        pkt->src_port = src->svm_port;
        pkt->dst_port = dst->svm_port;
        memset(&pkt->proto, 0, sizeof(pkt->proto));
        memset(&pkt->_reserved2, 0, sizeof(pkt->_reserved2));

        switch (pkt->type) {
        case VMCI_TRANSPORT_PACKET_TYPE_INVALID:
                pkt->u.size = 0;
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_REQUEST:
        case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
                pkt->u.size = size;
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_OFFER:
        case VMCI_TRANSPORT_PACKET_TYPE_ATTACH:
                pkt->u.handle = handle;
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_WROTE:
        case VMCI_TRANSPORT_PACKET_TYPE_READ:
        case VMCI_TRANSPORT_PACKET_TYPE_RST:
                pkt->u.size = 0;
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN:
                pkt->u.mode = mode;
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ:
        case VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE:
                memcpy(&pkt->u.wait, wait, sizeof(pkt->u.wait));
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_REQUEST2:
        case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
                pkt->u.size = size;
                pkt->proto = proto;
                break;
        }
}

static inline void
vmci_transport_packet_get_addresses(struct vmci_transport_packet *pkt,
                                    struct sockaddr_vm *local,
                                    struct sockaddr_vm *remote)
{
        vsock_addr_init(local, pkt->dg.dst.context, pkt->dst_port);
        vsock_addr_init(remote, pkt->dg.src.context, pkt->src_port);
}

static int
__vmci_transport_send_control_pkt(struct vmci_transport_packet *pkt,
                                  struct sockaddr_vm *src,
                                  struct sockaddr_vm *dst,
                                  enum vmci_transport_packet_type type,
                                  u64 size,
                                  u64 mode,
                                  struct vmci_transport_waiting_info *wait,
                                  u16 proto,
                                  struct vmci_handle handle,
                                  bool convert_error)
{
        int err;

        vmci_transport_packet_init(pkt, src, dst, type, size, mode, wait,
                                   proto, handle);
        err = vmci_datagram_send(&pkt->dg);
        if (convert_error && (err < 0))
                return vmci_transport_error_to_vsock_error(err);

        return err;
}

static int
vmci_transport_reply_control_pkt_fast(struct vmci_transport_packet *pkt,
                                      enum vmci_transport_packet_type type,
                                      u64 size,
                                      u64 mode,
                                      struct vmci_transport_waiting_info *wait,
                                      struct vmci_handle handle)
{
        struct vmci_transport_packet reply;
        struct sockaddr_vm src, dst;

        if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST) {
                return 0;
        } else {
                vmci_transport_packet_get_addresses(pkt, &src, &dst);
                return __vmci_transport_send_control_pkt(&reply, &src, &dst,
                                                         type,
                                                         size, mode, wait,
                                                         VSOCK_PROTO_INVALID,
                                                         handle, true);
        }
}

static int
vmci_transport_send_control_pkt_bh(struct sockaddr_vm *src,
                                   struct sockaddr_vm *dst,
                                   enum vmci_transport_packet_type type,
                                   u64 size,
                                   u64 mode,
                                   struct vmci_transport_waiting_info *wait,
                                   struct vmci_handle handle)
{
        /* Note that it is safe to use a single packet across all CPUs since
         * two tasklets of the same type are guaranteed to not ever run
         * simultaneously. If that ever changes, or VMCI stops using tasklets,
         * we can use per-cpu packets.
         */
        static struct vmci_transport_packet pkt;

        return __vmci_transport_send_control_pkt(&pkt, src, dst, type,
                                                 size, mode, wait,
                                                 VSOCK_PROTO_INVALID, handle,
                                                 false);
}

static int
vmci_transport_alloc_send_control_pkt(struct sockaddr_vm *src,
                                      struct sockaddr_vm *dst,
                                      enum vmci_transport_packet_type type,
                                      u64 size,
                                      u64 mode,
                                      struct vmci_transport_waiting_info *wait,
                                      u16 proto,
                                      struct vmci_handle handle)
{
        struct vmci_transport_packet *pkt;
        int err;

        pkt = kmalloc(sizeof(*pkt), GFP_KERNEL);
        if (!pkt)
                return -ENOMEM;

        err = __vmci_transport_send_control_pkt(pkt, src, dst, type, size,
                                                mode, wait, proto, handle,
                                                true);
        kfree(pkt);

        return err;
}

static int
vmci_transport_send_control_pkt(struct sock *sk,
                                enum vmci_transport_packet_type type,
                                u64 size,
                                u64 mode,
                                struct vmci_transport_waiting_info *wait,
                                u16 proto,
                                struct vmci_handle handle)
{
        struct vsock_sock *vsk;

        vsk = vsock_sk(sk);

        if (!vsock_addr_bound(&vsk->local_addr))
                return -EINVAL;

        if (!vsock_addr_bound(&vsk->remote_addr))
                return -EINVAL;

        return vmci_transport_alloc_send_control_pkt(&vsk->local_addr,
                                                     &vsk->remote_addr,
                                                     type, size, mode,
                                                     wait, proto, handle);
}

static int vmci_transport_send_reset_bh(struct sockaddr_vm *dst,
                                        struct sockaddr_vm *src,
                                        struct vmci_transport_packet *pkt)
{
        if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
                return 0;
        return vmci_transport_send_control_pkt_bh(
                                        dst, src,
                                        VMCI_TRANSPORT_PACKET_TYPE_RST, 0,
                                        0, NULL, VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_reset(struct sock *sk,
                                     struct vmci_transport_packet *pkt)
{
        struct sockaddr_vm *dst_ptr;
        struct sockaddr_vm dst;
        struct vsock_sock *vsk;

        if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST)
                return 0;

        vsk = vsock_sk(sk);

        if (!vsock_addr_bound(&vsk->local_addr))
                return -EINVAL;

        if (vsock_addr_bound(&vsk->remote_addr)) {
                dst_ptr = &vsk->remote_addr;
        } else {
                vsock_addr_init(&dst, pkt->dg.src.context,
                                pkt->src_port);
                dst_ptr = &dst;
        }
        return vmci_transport_alloc_send_control_pkt(&vsk->local_addr, dst_ptr,
                                             VMCI_TRANSPORT_PACKET_TYPE_RST,
                                             0, 0, NULL, VSOCK_PROTO_INVALID,
                                             VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_negotiate(struct sock *sk, size_t size)
{
        return vmci_transport_send_control_pkt(
                                        sk,
                                        VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE,
                                        size, 0, NULL,
                                        VSOCK_PROTO_INVALID,
                                        VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_negotiate2(struct sock *sk, size_t size,
                                          u16 version)
{
        return vmci_transport_send_control_pkt(
                                        sk,
                                        VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2,
                                        size, 0, NULL, version,
                                        VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_qp_offer(struct sock *sk,
                                        struct vmci_handle handle)
{
        return vmci_transport_send_control_pkt(
                                        sk, VMCI_TRANSPORT_PACKET_TYPE_OFFER, 0,
                                        0, NULL,
                                        VSOCK_PROTO_INVALID, handle);
}

static int vmci_transport_send_attach(struct sock *sk,
                                      struct vmci_handle handle)
{
        return vmci_transport_send_control_pkt(
                                        sk, VMCI_TRANSPORT_PACKET_TYPE_ATTACH,
                                        0, 0, NULL, VSOCK_PROTO_INVALID,
                                        handle);
}

static int vmci_transport_reply_reset(struct vmci_transport_packet *pkt)
{
        return vmci_transport_reply_control_pkt_fast(
                                                pkt,
                                                VMCI_TRANSPORT_PACKET_TYPE_RST,
                                                0, 0, NULL,
                                                VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_invalid_bh(struct sockaddr_vm *dst,
                                          struct sockaddr_vm *src)
{
        return vmci_transport_send_control_pkt_bh(
                                        dst, src,
                                        VMCI_TRANSPORT_PACKET_TYPE_INVALID,
                                        0, 0, NULL, VMCI_INVALID_HANDLE);
}

int vmci_transport_send_wrote_bh(struct sockaddr_vm *dst,
                                 struct sockaddr_vm *src)
{
        return vmci_transport_send_control_pkt_bh(
                                        dst, src,
                                        VMCI_TRANSPORT_PACKET_TYPE_WROTE, 0,
                                        0, NULL, VMCI_INVALID_HANDLE);
}

int vmci_transport_send_read_bh(struct sockaddr_vm *dst,
                                struct sockaddr_vm *src)
{
        return vmci_transport_send_control_pkt_bh(
                                        dst, src,
                                        VMCI_TRANSPORT_PACKET_TYPE_READ, 0,
                                        0, NULL, VMCI_INVALID_HANDLE);
}

int vmci_transport_send_wrote(struct sock *sk)
{
        return vmci_transport_send_control_pkt(
                                        sk, VMCI_TRANSPORT_PACKET_TYPE_WROTE, 0,
                                        0, NULL, VSOCK_PROTO_INVALID,
                                        VMCI_INVALID_HANDLE);
}

int vmci_transport_send_read(struct sock *sk)
{
        return vmci_transport_send_control_pkt(
                                        sk, VMCI_TRANSPORT_PACKET_TYPE_READ, 0,
                                        0, NULL, VSOCK_PROTO_INVALID,
                                        VMCI_INVALID_HANDLE);
}

int vmci_transport_send_waiting_write(struct sock *sk,
                                      struct vmci_transport_waiting_info *wait)
{
        return vmci_transport_send_control_pkt(
                                sk, VMCI_TRANSPORT_PACKET_TYPE_WAITING_WRITE,
                                0, 0, wait, VSOCK_PROTO_INVALID,
                                VMCI_INVALID_HANDLE);
}

int vmci_transport_send_waiting_read(struct sock *sk,
                                     struct vmci_transport_waiting_info *wait)
{
        return vmci_transport_send_control_pkt(
                                sk, VMCI_TRANSPORT_PACKET_TYPE_WAITING_READ,
                                0, 0, wait, VSOCK_PROTO_INVALID,
                                VMCI_INVALID_HANDLE);
}

static int vmci_transport_shutdown(struct vsock_sock *vsk, int mode)
{
        return vmci_transport_send_control_pkt(
                                        &vsk->sk,
                                        VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN,
                                        0, mode, NULL,
                                        VSOCK_PROTO_INVALID,
                                        VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_conn_request(struct sock *sk, size_t size)
{
        return vmci_transport_send_control_pkt(sk,
                                        VMCI_TRANSPORT_PACKET_TYPE_REQUEST,
                                        size, 0, NULL,
                                        VSOCK_PROTO_INVALID,
                                        VMCI_INVALID_HANDLE);
}

static int vmci_transport_send_conn_request2(struct sock *sk, size_t size,
                                             u16 version)
{
        return vmci_transport_send_control_pkt(
                                        sk, VMCI_TRANSPORT_PACKET_TYPE_REQUEST2,
                                        size, 0, NULL, version,
                                        VMCI_INVALID_HANDLE);
}

static struct sock *vmci_transport_get_pending(
                                        struct sock *listener,
                                        struct vmci_transport_packet *pkt)
{
        struct vsock_sock *vlistener;
        struct vsock_sock *vpending;
        struct sock *pending;
        struct sockaddr_vm src;

        vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);

        vlistener = vsock_sk(listener);

        list_for_each_entry(vpending, &vlistener->pending_links,
                            pending_links) {
                if (vsock_addr_equals_addr(&src, &vpending->remote_addr) &&
                    pkt->dst_port == vpending->local_addr.svm_port) {
                        pending = sk_vsock(vpending);
                        sock_hold(pending);
                        goto found;
                }
        }

        pending = NULL;
found:
        return pending;

}

static void vmci_transport_release_pending(struct sock *pending)
{
        sock_put(pending);
}

/* We allow two kinds of sockets to communicate with a restricted VM: 1)
 * trusted sockets 2) sockets from applications running as the same user as the
 * VM (this is only true for the host side and only when using hosted products)
 */

static bool vmci_transport_is_trusted(struct vsock_sock *vsock, u32 peer_cid)
{
        return vsock->trusted ||
               vmci_is_context_owner(peer_cid, vsock->owner->uid);
}

/* We allow sending datagrams to and receiving datagrams from a restricted VM
 * only if it is trusted as described in vmci_transport_is_trusted.
 */

static bool vmci_transport_allow_dgram(struct vsock_sock *vsock, u32 peer_cid)
{
        if (VMADDR_CID_HYPERVISOR == peer_cid)
                return true;

        if (vsock->cached_peer != peer_cid) {
                vsock->cached_peer = peer_cid;
                if (!vmci_transport_is_trusted(vsock, peer_cid) &&
                    (vmci_context_get_priv_flags(peer_cid) &
                     VMCI_PRIVILEGE_FLAG_RESTRICTED)) {
                        vsock->cached_peer_allow_dgram = false;
                } else {
                        vsock->cached_peer_allow_dgram = true;
                }
        }

        return vsock->cached_peer_allow_dgram;
}

static int
vmci_transport_queue_pair_alloc(struct vmci_qp **qpair,
                                struct vmci_handle *handle,
                                u64 produce_size,
                                u64 consume_size,
                                u32 peer, u32 flags, bool trusted)
{
        int err = 0;

        if (trusted) {
                /* Try to allocate our queue pair as trusted. This will only
                 * work if vsock is running in the host.
                 */

                err = vmci_qpair_alloc(qpair, handle, produce_size,
                                       consume_size,
                                       peer, flags,
                                       VMCI_PRIVILEGE_FLAG_TRUSTED);
                if (err != VMCI_ERROR_NO_ACCESS)
                        goto out;

        }

        err = vmci_qpair_alloc(qpair, handle, produce_size, consume_size,
                               peer, flags, VMCI_NO_PRIVILEGE_FLAGS);
out:
        if (err < 0) {
                pr_err("Could not attach to queue pair with %d\n",
                       err);
                err = vmci_transport_error_to_vsock_error(err);
        }

        return err;
}

static int
vmci_transport_datagram_create_hnd(u32 resource_id,
                                   u32 flags,
                                   vmci_datagram_recv_cb recv_cb,
                                   void *client_data,
                                   struct vmci_handle *out_handle)
{
        int err = 0;

        /* Try to allocate our datagram handler as trusted. This will only work
         * if vsock is running in the host.
         */

        err = vmci_datagram_create_handle_priv(resource_id, flags,
                                               VMCI_PRIVILEGE_FLAG_TRUSTED,
                                               recv_cb,
                                               client_data, out_handle);

        if (err == VMCI_ERROR_NO_ACCESS)
                err = vmci_datagram_create_handle(resource_id, flags,
                                                  recv_cb, client_data,
                                                  out_handle);

        return err;
}

/* This is invoked as part of a tasklet that's scheduled when the VMCI
 * interrupt fires.  This is run in bottom-half context and if it ever needs to
 * sleep it should defer that work to a work queue.
 */

static int vmci_transport_recv_dgram_cb(void *data, struct vmci_datagram *dg)
{
        struct sock *sk;
        size_t size;
        struct sk_buff *skb;
        struct vsock_sock *vsk;

        sk = (struct sock *)data;

        /* This handler is privileged when this module is running on the host.
         * We will get datagrams from all endpoints (even VMs that are in a
         * restricted context). If we get one from a restricted context then
         * the destination socket must be trusted.
         *
         * NOTE: We access the socket struct without holding the lock here.
         * This is ok because the field we are interested is never modified
         * outside of the create and destruct socket functions.
         */
        vsk = vsock_sk(sk);
        if (!vmci_transport_allow_dgram(vsk, dg->src.context))
                return VMCI_ERROR_NO_ACCESS;

        size = VMCI_DG_SIZE(dg);

        /* Attach the packet to the socket's receive queue as an sk_buff. */
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb)
                return VMCI_ERROR_NO_MEM;

        /* sk_receive_skb() will do a sock_put(), so hold here. */
        sock_hold(sk);
        skb_put(skb, size);
        memcpy(skb->data, dg, size);
        sk_receive_skb(sk, skb, 0);

        return VMCI_SUCCESS;
}

static bool vmci_transport_stream_allow(u32 cid, u32 port)
{
        static const u32 non_socket_contexts[] = {
                VMADDR_CID_RESERVED,
        };
        int i;

        BUILD_BUG_ON(sizeof(cid) != sizeof(*non_socket_contexts));

        for (i = 0; i < ARRAY_SIZE(non_socket_contexts); i++) {
                if (cid == non_socket_contexts[i])
                        return false;
        }

        return true;
}

/* This is invoked as part of a tasklet that's scheduled when the VMCI
 * interrupt fires.  This is run in bottom-half context but it defers most of
 * its work to the packet handling work queue.
 */

static int vmci_transport_recv_stream_cb(void *data, struct vmci_datagram *dg)
{
        struct sock *sk;
        struct sockaddr_vm dst;
        struct sockaddr_vm src;
        struct vmci_transport_packet *pkt;
        struct vsock_sock *vsk;
        bool bh_process_pkt;
        int err;

        sk = NULL;
        err = VMCI_SUCCESS;
        bh_process_pkt = false;

        /* Ignore incoming packets from contexts without sockets, or resources
         * that aren't vsock implementations.
         */

        if (!vmci_transport_stream_allow(dg->src.context, -1)
            || vmci_transport_peer_rid(dg->src.context) != dg->src.resource)
                return VMCI_ERROR_NO_ACCESS;

        if (VMCI_DG_SIZE(dg) < sizeof(*pkt))
                /* Drop datagrams that do not contain full VSock packets. */
                return VMCI_ERROR_INVALID_ARGS;

        pkt = (struct vmci_transport_packet *)dg;

        /* Find the socket that should handle this packet.  First we look for a
         * connected socket and if there is none we look for a socket bound to
         * the destintation address.
         */
        vsock_addr_init(&src, pkt->dg.src.context, pkt->src_port);
        vsock_addr_init(&dst, pkt->dg.dst.context, pkt->dst_port);

        sk = vsock_find_connected_socket(&src, &dst);
        if (!sk) {
                sk = vsock_find_bound_socket(&dst);
                if (!sk) {
                        /* We could not find a socket for this specified
                         * address.  If this packet is a RST, we just drop it.
                         * If it is another packet, we send a RST.  Note that
                         * we do not send a RST reply to RSTs so that we do not
                         * continually send RSTs between two endpoints.
                         *
                         * Note that since this is a reply, dst is src and src
                         * is dst.
                         */
                        if (vmci_transport_send_reset_bh(&dst, &src, pkt) < 0)
                                pr_err("unable to send reset\n");

                        err = VMCI_ERROR_NOT_FOUND;
                        goto out;
                }
        }

        /* If the received packet type is beyond all types known to this
         * implementation, reply with an invalid message.  Hopefully this will
         * help when implementing backwards compatibility in the future.
         */
        if (pkt->type >= VMCI_TRANSPORT_PACKET_TYPE_MAX) {
                vmci_transport_send_invalid_bh(&dst, &src);
                err = VMCI_ERROR_INVALID_ARGS;
                goto out;
        }

        /* This handler is privileged when this module is running on the host.
         * We will get datagram connect requests from all endpoints (even VMs
         * that are in a restricted context). If we get one from a restricted
         * context then the destination socket must be trusted.
         *
         * NOTE: We access the socket struct without holding the lock here.
         * This is ok because the field we are interested is never modified
         * outside of the create and destruct socket functions.
         */
        vsk = vsock_sk(sk);
        if (!vmci_transport_allow_dgram(vsk, pkt->dg.src.context)) {
                err = VMCI_ERROR_NO_ACCESS;
                goto out;
        }

        /* We do most everything in a work queue, but let's fast path the
         * notification of reads and writes to help data transfer performance.
         * We can only do this if there is no process context code executing
         * for this socket since that may change the state.
         */
        bh_lock_sock(sk);

        if (!sock_owned_by_user(sk)) {
                /* The local context ID may be out of date, update it. */
                vsk->local_addr.svm_cid = dst.svm_cid;

                if (sk->sk_state == TCP_ESTABLISHED)
                        vmci_trans(vsk)->notify_ops->handle_notify_pkt(
                                        sk, pkt, true, &dst, &src,
                                        &bh_process_pkt);
        }

        bh_unlock_sock(sk);

        if (!bh_process_pkt) {
                struct vmci_transport_recv_pkt_info *recv_pkt_info;

                recv_pkt_info = kmalloc(sizeof(*recv_pkt_info), GFP_ATOMIC);
                if (!recv_pkt_info) {
                        if (vmci_transport_send_reset_bh(&dst, &src, pkt) < 0)
                                pr_err("unable to send reset\n");

                        err = VMCI_ERROR_NO_MEM;
                        goto out;
                }

                recv_pkt_info->sk = sk;
                memcpy(&recv_pkt_info->pkt, pkt, sizeof(recv_pkt_info->pkt));
                INIT_WORK(&recv_pkt_info->work, vmci_transport_recv_pkt_work);

                schedule_work(&recv_pkt_info->work);
                /* Clear sk so that the reference count incremented by one of
                 * the Find functions above is not decremented below.  We need
                 * that reference count for the packet handler we've scheduled
                 * to run.
                 */
                sk = NULL;
        }

out:
        if (sk)
                sock_put(sk);

        return err;
}

static void vmci_transport_handle_detach(struct sock *sk)
{
        struct vsock_sock *vsk;

        vsk = vsock_sk(sk);
        if (!vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)) {
                sock_set_flag(sk, SOCK_DONE);

                /* On a detach the peer will not be sending or receiving
                 * anymore.
                 */
                vsk->peer_shutdown = SHUTDOWN_MASK;

                /* We should not be sending anymore since the peer won't be
                 * there to receive, but we can still receive if there is data
                 * left in our consume queue. If the local endpoint is a host,
                 * we can't call vsock_stream_has_data, since that may block,
                 * but a host endpoint can't read data once the VM has
                 * detached, so there is no available data in that case.
                 */
                if (vsk->local_addr.svm_cid == VMADDR_CID_HOST ||
                    vsock_stream_has_data(vsk) <= 0) {
                        if (sk->sk_state == TCP_SYN_SENT) {
                                /* The peer may detach from a queue pair while
                                 * we are still in the connecting state, i.e.,
                                 * if the peer VM is killed after attaching to
                                 * a queue pair, but before we complete the
                                 * handshake. In that case, we treat the detach
                                 * event like a reset.
                                 */

                                sk->sk_state = TCP_CLOSE;
                                sk->sk_err = ECONNRESET;
                                sk->sk_error_report(sk);
                                return;
                        }
                        sk->sk_state = TCP_CLOSE;
                }
                sk->sk_state_change(sk);
        }
}

static void vmci_transport_peer_detach_cb(u32 sub_id,
                                          const struct vmci_event_data *e_data,
                                          void *client_data)
{
        struct vmci_transport *trans = client_data;
        const struct vmci_event_payload_qp *e_payload;

        e_payload = vmci_event_data_const_payload(e_data);

        /* XXX This is lame, we should provide a way to lookup sockets by
         * qp_handle.
         */
        if (vmci_handle_is_invalid(e_payload->handle) ||
            !vmci_handle_is_equal(trans->qp_handle, e_payload->handle))
                return;

        /* We don't ask for delayed CBs when we subscribe to this event (we
         * pass 0 as flags to vmci_event_subscribe()).  VMCI makes no
         * guarantees in that case about what context we might be running in,
         * so it could be BH or process, blockable or non-blockable.  So we
         * need to account for all possible contexts here.
         */
        spin_lock_bh(&trans->lock);
        if (!trans->sk)
                goto out;

        /* Apart from here, trans->lock is only grabbed as part of sk destruct,
         * where trans->sk isn't locked.
         */
        bh_lock_sock(trans->sk);

        vmci_transport_handle_detach(trans->sk);

        bh_unlock_sock(trans->sk);
 out:
        spin_unlock_bh(&trans->lock);
}

static void vmci_transport_qp_resumed_cb(u32 sub_id,
                                         const struct vmci_event_data *e_data,
                                         void *client_data)
{
        vsock_for_each_connected_socket(vmci_transport_handle_detach);
}

static void vmci_transport_recv_pkt_work(struct work_struct *work)
{
        struct vmci_transport_recv_pkt_info *recv_pkt_info;
        struct vmci_transport_packet *pkt;
        struct sock *sk;

        recv_pkt_info =
                container_of(work, struct vmci_transport_recv_pkt_info, work);
        sk = recv_pkt_info->sk;
        pkt = &recv_pkt_info->pkt;

        lock_sock(sk);

        /* The local context ID may be out of date. */
        vsock_sk(sk)->local_addr.svm_cid = pkt->dg.dst.context;

        switch (sk->sk_state) {
        case TCP_LISTEN:
                vmci_transport_recv_listen(sk, pkt);
                break;
        case TCP_SYN_SENT:
                /* Processing of pending connections for servers goes through
                 * the listening socket, so see vmci_transport_recv_listen()
                 * for that path.
                 */
                vmci_transport_recv_connecting_client(sk, pkt);
                break;
        case TCP_ESTABLISHED:
                vmci_transport_recv_connected(sk, pkt);
                break;
        default:
                /* Because this function does not run in the same context as
                 * vmci_transport_recv_stream_cb it is possible that the
                 * socket has closed. We need to let the other side know or it
                 * could be sitting in a connect and hang forever. Send a
                 * reset to prevent that.
                 */
                vmci_transport_send_reset(sk, pkt);
                break;
        }

        release_sock(sk);
        kfree(recv_pkt_info);
        /* Release reference obtained in the stream callback when we fetched
         * this socket out of the bound or connected list.
         */
        sock_put(sk);
}

static int vmci_transport_recv_listen(struct sock *sk,
                                      struct vmci_transport_packet *pkt)
{
        struct sock *pending;
        struct vsock_sock *vpending;
        int err;
        u64 qp_size;
        bool old_request = false;
        bool old_pkt_proto = false;

        err = 0;

        /* Because we are in the listen state, we could be receiving a packet
         * for ourself or any previous connection requests that we received.
         * If it's the latter, we try to find a socket in our list of pending
         * connections and, if we do, call the appropriate handler for the
         * state that that socket is in.  Otherwise we try to service the
         * connection request.
         */
        pending = vmci_transport_get_pending(sk, pkt);
        if (pending) {
                lock_sock(pending);

                /* The local context ID may be out of date. */
                vsock_sk(pending)->local_addr.svm_cid = pkt->dg.dst.context;

                switch (pending->sk_state) {
                case TCP_SYN_SENT:
                        err = vmci_transport_recv_connecting_server(sk,
                                                                    pending,
                                                                    pkt);
                        break;
                default:
                        vmci_transport_send_reset(pending, pkt);
                        err = -EINVAL;
                }

                if (err < 0)
                        vsock_remove_pending(sk, pending);

                release_sock(pending);
                vmci_transport_release_pending(pending);

                return err;
        }

        /* The listen state only accepts connection requests.  Reply with a
         * reset unless we received a reset.
         */

        if (!(pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST ||
              pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST2)) {
                vmci_transport_reply_reset(pkt);
                return -EINVAL;
        }

        if (pkt->u.size == 0) {
                vmci_transport_reply_reset(pkt);
                return -EINVAL;
        }

        /* If this socket can't accommodate this connection request, we send a
         * reset.  Otherwise we create and initialize a child socket and reply
         * with a connection negotiation.
         */
        if (sk->sk_ack_backlog >= sk->sk_max_ack_backlog) {
                vmci_transport_reply_reset(pkt);
                return -ECONNREFUSED;
        }

        pending = __vsock_create(sock_net(sk), NULL, sk, GFP_KERNEL,
                                 sk->sk_type, 0);
        if (!pending) {
                vmci_transport_send_reset(sk, pkt);
                return -ENOMEM;
        }

        vpending = vsock_sk(pending);

        vsock_addr_init(&vpending->local_addr, pkt->dg.dst.context,
                        pkt->dst_port);
        vsock_addr_init(&vpending->remote_addr, pkt->dg.src.context,
                        pkt->src_port);

        /* If the proposed size fits within our min/max, accept it. Otherwise
         * propose our own size.
         */
        if (pkt->u.size >= vmci_trans(vpending)->queue_pair_min_size &&
            pkt->u.size <= vmci_trans(vpending)->queue_pair_max_size) {
                qp_size = pkt->u.size;
        } else {
                qp_size = vmci_trans(vpending)->queue_pair_size;
        }

        /* Figure out if we are using old or new requests based on the
         * overrides pkt types sent by our peer.
         */
        if (vmci_transport_old_proto_override(&old_pkt_proto)) {
                old_request = old_pkt_proto;
        } else {
                if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST)
                        old_request = true;
                else if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_REQUEST2)
                        old_request = false;

        }

        if (old_request) {
                /* Handle a REQUEST (or override) */
                u16 version = VSOCK_PROTO_INVALID;
                if (vmci_transport_proto_to_notify_struct(
                        pending, &version, true))
                        err = vmci_transport_send_negotiate(pending, qp_size);
                else
                        err = -EINVAL;

        } else {
                /* Handle a REQUEST2 (or override) */
                int proto_int = pkt->proto;
                int pos;
                u16 active_proto_version = 0;

                /* The list of possible protocols is the intersection of all
                 * protocols the client supports ... plus all the protocols we
                 * support.
                 */
                proto_int &= vmci_transport_new_proto_supported_versions();

                /* We choose the highest possible protocol version and use that
                 * one.
                 */
                pos = fls(proto_int);
                if (pos) {
                        active_proto_version = (1 << (pos - 1));
                        if (vmci_transport_proto_to_notify_struct(
                                pending, &active_proto_version, false))
                                err = vmci_transport_send_negotiate2(pending,
                                                        qp_size,
                                                        active_proto_version);
                        else
                                err = -EINVAL;

                } else {
                        err = -EINVAL;
                }
        }

        if (err < 0) {
                vmci_transport_send_reset(sk, pkt);
                sock_put(pending);
                err = vmci_transport_error_to_vsock_error(err);
                goto out;
        }

        vsock_add_pending(sk, pending);
        sk->sk_ack_backlog++;

        pending->sk_state = TCP_SYN_SENT;
        vmci_trans(vpending)->produce_size =
                vmci_trans(vpending)->consume_size = qp_size;
        vmci_trans(vpending)->queue_pair_size = qp_size;

        vmci_trans(vpending)->notify_ops->process_request(pending);

        /* We might never receive another message for this socket and it's not
         * connected to any process, so we have to ensure it gets cleaned up
         * ourself.  Our delayed work function will take care of that.  Note
         * that we do not ever cancel this function since we have few
         * guarantees about its state when calling cancel_delayed_work().
         * Instead we hold a reference on the socket for that function and make
         * it capable of handling cases where it needs to do nothing but
         * release that reference.
         */
        vpending->listener = sk;
        sock_hold(sk);
        sock_hold(pending);
        schedule_delayed_work(&vpending->pending_work, HZ);

out:
        return err;
}

static int
vmci_transport_recv_connecting_server(struct sock *listener,
                                      struct sock *pending,
                                      struct vmci_transport_packet *pkt)
{
        struct vsock_sock *vpending;
        struct vmci_handle handle;
        struct vmci_qp *qpair;
        bool is_local;
        u32 flags;
        u32 detach_sub_id;
        int err;
        int skerr;

        vpending = vsock_sk(pending);
        detach_sub_id = VMCI_INVALID_ID;

        switch (pkt->type) {
        case VMCI_TRANSPORT_PACKET_TYPE_OFFER:
                if (vmci_handle_is_invalid(pkt->u.handle)) {
                        vmci_transport_send_reset(pending, pkt);
                        skerr = EPROTO;
                        err = -EINVAL;
                        goto destroy;
                }
                break;
        default:
                /* Close and cleanup the connection. */
                vmci_transport_send_reset(pending, pkt);
                skerr = EPROTO;
                err = pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST ? 0 : -EINVAL;
                goto destroy;
        }

        /* In order to complete the connection we need to attach to the offered
         * queue pair and send an attach notification.  We also subscribe to the
         * detach event so we know when our peer goes away, and we do that
         * before attaching so we don't miss an event.  If all this succeeds,
         * we update our state and wakeup anything waiting in accept() for a
         * connection.
         */

        /* We don't care about attach since we ensure the other side has
         * attached by specifying the ATTACH_ONLY flag below.
         */
        err = vmci_event_subscribe(VMCI_EVENT_QP_PEER_DETACH,
                                   vmci_transport_peer_detach_cb,
                                   vmci_trans(vpending), &detach_sub_id);
        if (err < VMCI_SUCCESS) {
                vmci_transport_send_reset(pending, pkt);
                err = vmci_transport_error_to_vsock_error(err);
                skerr = -err;
                goto destroy;
        }

        vmci_trans(vpending)->detach_sub_id = detach_sub_id;

        /* Now attach to the queue pair the client created. */
        handle = pkt->u.handle;

        /* vpending->local_addr always has a context id so we do not need to
         * worry about VMADDR_CID_ANY in this case.
         */
        is_local =
            vpending->remote_addr.svm_cid == vpending->local_addr.svm_cid;
        flags = VMCI_QPFLAG_ATTACH_ONLY;
        flags |= is_local ? VMCI_QPFLAG_LOCAL : 0;

        err = vmci_transport_queue_pair_alloc(
                                        &qpair,
                                        &handle,
                                        vmci_trans(vpending)->produce_size,
                                        vmci_trans(vpending)->consume_size,
                                        pkt->dg.src.context,
                                        flags,
                                        vmci_transport_is_trusted(
                                                vpending,
                                                vpending->remote_addr.svm_cid));
        if (err < 0) {
                vmci_transport_send_reset(pending, pkt);
                skerr = -err;
                goto destroy;
        }

        vmci_trans(vpending)->qp_handle = handle;
        vmci_trans(vpending)->qpair = qpair;

        /* When we send the attach message, we must be ready to handle incoming
         * control messages on the newly connected socket. So we move the
         * pending socket to the connected state before sending the attach
         * message. Otherwise, an incoming packet triggered by the attach being
         * received by the peer may be processed concurrently with what happens
         * below after sending the attach message, and that incoming packet
         * will find the listening socket instead of the (currently) pending
         * socket. Note that enqueueing the socket increments the reference
         * count, so even if a reset comes before the connection is accepted,
         * the socket will be valid until it is removed from the queue.
         *
         * If we fail sending the attach below, we remove the socket from the
         * connected list and move the socket to TCP_CLOSE before
         * releasing the lock, so a pending slow path processing of an incoming
         * packet will not see the socket in the connected state in that case.
         */
        pending->sk_state = TCP_ESTABLISHED;

        vsock_insert_connected(vpending);

        /* Notify our peer of our attach. */
        err = vmci_transport_send_attach(pending, handle);
        if (err < 0) {
                vsock_remove_connected(vpending);
                pr_err("Could not send attach\n");
                vmci_transport_send_reset(pending, pkt);
                err = vmci_transport_error_to_vsock_error(err);
                skerr = -err;
                goto destroy;
        }

        /* We have a connection. Move the now connected socket from the
         * listener's pending list to the accept queue so callers of accept()
         * can find it.
         */
        vsock_remove_pending(listener, pending);
        vsock_enqueue_accept(listener, pending);

        /* Callers of accept() will be be waiting on the listening socket, not
         * the pending socket.
         */
        listener->sk_data_ready(listener);

        return 0;

destroy:
        pending->sk_err = skerr;
        pending->sk_state = TCP_CLOSE;
        /* As long as we drop our reference, all necessary cleanup will handle
         * when the cleanup function drops its reference and our destruct
         * implementation is called.  Note that since the listen handler will
         * remove pending from the pending list upon our failure, the cleanup
         * function won't drop the additional reference, which is why we do it
         * here.
         */
        sock_put(pending);

        return err;
}

static int
vmci_transport_recv_connecting_client(struct sock *sk,
                                      struct vmci_transport_packet *pkt)
{
        struct vsock_sock *vsk;
        int err;
        int skerr;

        vsk = vsock_sk(sk);

        switch (pkt->type) {
        case VMCI_TRANSPORT_PACKET_TYPE_ATTACH:
                if (vmci_handle_is_invalid(pkt->u.handle) ||
                    !vmci_handle_is_equal(pkt->u.handle,
                                          vmci_trans(vsk)->qp_handle)) {
                        skerr = EPROTO;
                        err = -EINVAL;
                        goto destroy;
                }

                /* Signify the socket is connected and wakeup the waiter in
                 * connect(). Also place the socket in the connected table for
                 * accounting (it can already be found since it's in the bound
                 * table).
                 */
                sk->sk_state = TCP_ESTABLISHED;
                sk->sk_socket->state = SS_CONNECTED;
                vsock_insert_connected(vsk);
                sk->sk_state_change(sk);

                break;
        case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE:
        case VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2:
                if (pkt->u.size == 0
                    || pkt->dg.src.context != vsk->remote_addr.svm_cid
                    || pkt->src_port != vsk->remote_addr.svm_port
                    || !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle)
                    || vmci_trans(vsk)->qpair
                    || vmci_trans(vsk)->produce_size != 0
                    || vmci_trans(vsk)->consume_size != 0
                    || vmci_trans(vsk)->detach_sub_id != VMCI_INVALID_ID) {
                        skerr = EPROTO;
                        err = -EINVAL;

                        goto destroy;
                }

                err = vmci_transport_recv_connecting_client_negotiate(sk, pkt);
                if (err) {
                        skerr = -err;
                        goto destroy;
                }

                break;
        case VMCI_TRANSPORT_PACKET_TYPE_INVALID:
                err = vmci_transport_recv_connecting_client_invalid(sk, pkt);
                if (err) {
                        skerr = -err;
                        goto destroy;
                }

                break;
        case VMCI_TRANSPORT_PACKET_TYPE_RST:
                /* Older versions of the linux code (WS 6.5 / ESX 4.0) used to
                 * continue processing here after they sent an INVALID packet.
                 * This meant that we got a RST after the INVALID. We ignore a
                 * RST after an INVALID. The common code doesn't send the RST
                 * ... so we can hang if an old version of the common code
                 * fails between getting a REQUEST and sending an OFFER back.
                 * Not much we can do about it... except hope that it doesn't
                 * happen.
                 */
                if (vsk->ignore_connecting_rst) {
                        vsk->ignore_connecting_rst = false;
                } else {
                        skerr = ECONNRESET;
                        err = 0;
                        goto destroy;
                }

                break;
        default:
                /* Close and cleanup the connection. */
                skerr = EPROTO;
                err = -EINVAL;
                goto destroy;
        }

        return 0;

destroy:
        vmci_transport_send_reset(sk, pkt);

        sk->sk_state = TCP_CLOSE;
        sk->sk_err = skerr;
        sk->sk_error_report(sk);
        return err;
}

static int vmci_transport_recv_connecting_client_negotiate(
                                        struct sock *sk,
                                        struct vmci_transport_packet *pkt)
{
        int err;
        struct vsock_sock *vsk;
        struct vmci_handle handle;
        struct vmci_qp *qpair;
        u32 detach_sub_id;
        bool is_local;
        u32 flags;
        bool old_proto = true;
        bool old_pkt_proto;
        u16 version;

        vsk = vsock_sk(sk);
        handle = VMCI_INVALID_HANDLE;
        detach_sub_id = VMCI_INVALID_ID;

        /* If we have gotten here then we should be past the point where old
         * linux vsock could have sent the bogus rst.
         */
        vsk->sent_request = false;
        vsk->ignore_connecting_rst = false;

        /* Verify that we're OK with the proposed queue pair size */
        if (pkt->u.size < vmci_trans(vsk)->queue_pair_min_size ||
            pkt->u.size > vmci_trans(vsk)->queue_pair_max_size) {
                err = -EINVAL;
                goto destroy;
        }

        /* At this point we know the CID the peer is using to talk to us. */

        if (vsk->local_addr.svm_cid == VMADDR_CID_ANY)
                vsk->local_addr.svm_cid = pkt->dg.dst.context;

        /* Setup the notify ops to be the highest supported version that both
         * the server and the client support.
         */

        if (vmci_transport_old_proto_override(&old_pkt_proto)) {
                old_proto = old_pkt_proto;
        } else {
                if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE)
                        old_proto = true;
                else if (pkt->type == VMCI_TRANSPORT_PACKET_TYPE_NEGOTIATE2)
                        old_proto = false;

        }

        if (old_proto)
                version = VSOCK_PROTO_INVALID;
        else
                version = pkt->proto;

        if (!vmci_transport_proto_to_notify_struct(sk, &version, old_proto)) {
                err = -EINVAL;
                goto destroy;
        }

        /* Subscribe to detach events first.
         *
         * XXX We attach once for each queue pair created for now so it is easy
         * to find the socket (it's provided), but later we should only
         * subscribe once and add a way to lookup sockets by queue pair handle.
         */
        err = vmci_event_subscribe(VMCI_EVENT_QP_PEER_DETACH,
                                   vmci_transport_peer_detach_cb,
                                   vmci_trans(vsk), &detach_sub_id);
        if (err < VMCI_SUCCESS) {
                err = vmci_transport_error_to_vsock_error(err);
                goto destroy;
        }

        /* Make VMCI select the handle for us. */
        handle = VMCI_INVALID_HANDLE;
        is_local = vsk->remote_addr.svm_cid == vsk->local_addr.svm_cid;
        flags = is_local ? VMCI_QPFLAG_LOCAL : 0;

        err = vmci_transport_queue_pair_alloc(&qpair,
                                              &handle,
                                              pkt->u.size,
                                              pkt->u.size,
                                              vsk->remote_addr.svm_cid,
                                              flags,
                                              vmci_transport_is_trusted(
                                                  vsk,
                                                  vsk->
                                                  remote_addr.svm_cid));
        if (err < 0)
                goto destroy;

        err = vmci_transport_send_qp_offer(sk, handle);
        if (err < 0) {
                err = vmci_transport_error_to_vsock_error(err);
                goto destroy;
        }

        vmci_trans(vsk)->qp_handle = handle;
        vmci_trans(vsk)->qpair = qpair;

        vmci_trans(vsk)->produce_size = vmci_trans(vsk)->consume_size =
                pkt->u.size;

        vmci_trans(vsk)->detach_sub_id = detach_sub_id;

        vmci_trans(vsk)->notify_ops->process_negotiate(sk);

        return 0;

destroy:
        if (detach_sub_id != VMCI_INVALID_ID)
                vmci_event_unsubscribe(detach_sub_id);

        if (!vmci_handle_is_invalid(handle))
                vmci_qpair_detach(&qpair);

        return err;
}

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

        if (vsk->sent_request) {
                vsk->sent_request = false;
                vsk->ignore_connecting_rst = true;

                err = vmci_transport_send_conn_request(
                        sk, vmci_trans(vsk)->queue_pair_size);
                if (err < 0)
                        err = vmci_transport_error_to_vsock_error(err);
                else
                        err = 0;

        }

        return err;
}

static int vmci_transport_recv_connected(struct sock *sk,
                                         struct vmci_transport_packet *pkt)
{
        struct vsock_sock *vsk;
        bool pkt_processed = false;

        /* In cases where we are closing the connection, it's sufficient to
         * mark the state change (and maybe error) and wake up any waiting
         * threads. Since this is a connected socket, it's owned by a user
         * process and will be cleaned up when the failure is passed back on
         * the current or next system call.  Our system call implementations
         * must therefore check for error and state changes on entry and when
         * being awoken.
         */
        switch (pkt->type) {
        case VMCI_TRANSPORT_PACKET_TYPE_SHUTDOWN:
                if (pkt->u.mode) {
                        vsk = vsock_sk(sk);

                        vsk->peer_shutdown |= pkt->u.mode;
                        sk->sk_state_change(sk);
                }
                break;

        case VMCI_TRANSPORT_PACKET_TYPE_RST:
                vsk = vsock_sk(sk);
                /* It is possible that we sent our peer a message (e.g a
                 * WAITING_READ) right before we got notified that the peer had
                 * detached. If that happens then we can get a RST pkt back
                 * from our peer even though there is data available for us to
                 * read. In that case, don't shutdown the socket completely but
                 * instead allow the local client to finish reading data off
                 * the queuepair. Always treat a RST pkt in connected mode like
                 * a clean shutdown.
                 */
                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);
                break;

        default:
                vsk = vsock_sk(sk);
                vmci_trans(vsk)->notify_ops->handle_notify_pkt(
                                sk, pkt, false, NULL, NULL,
                                &pkt_processed);
                if (!pkt_processed)
                        return -EINVAL;

                break;
        }

        return 0;
}

static int vmci_transport_socket_init(struct vsock_sock *vsk,
                                      struct vsock_sock *psk)
{
        vsk->trans = kmalloc(sizeof(struct vmci_transport), GFP_KERNEL);
        if (!vsk->trans)
                return -ENOMEM;

        vmci_trans(vsk)->dg_handle = VMCI_INVALID_HANDLE;
        vmci_trans(vsk)->qp_handle = VMCI_INVALID_HANDLE;
        vmci_trans(vsk)->qpair = NULL;
        vmci_trans(vsk)->produce_size = vmci_trans(vsk)->consume_size = 0;
        vmci_trans(vsk)->detach_sub_id = VMCI_INVALID_ID;
        vmci_trans(vsk)->notify_ops = NULL;
        INIT_LIST_HEAD(&vmci_trans(vsk)->elem);
        vmci_trans(vsk)->sk = &vsk->sk;
        spin_lock_init(&vmci_trans(vsk)->lock);
        if (psk) {
                vmci_trans(vsk)->queue_pair_size =
                        vmci_trans(psk)->queue_pair_size;
                vmci_trans(vsk)->queue_pair_min_size =
                        vmci_trans(psk)->queue_pair_min_size;
                vmci_trans(vsk)->queue_pair_max_size =
                        vmci_trans(psk)->queue_pair_max_size;
        } else {
                vmci_trans(vsk)->queue_pair_size =
                        VMCI_TRANSPORT_DEFAULT_QP_SIZE;
                vmci_trans(vsk)->queue_pair_min_size =
                         VMCI_TRANSPORT_DEFAULT_QP_SIZE_MIN;
                vmci_trans(vsk)->queue_pair_max_size =
                        VMCI_TRANSPORT_DEFAULT_QP_SIZE_MAX;
        }

        return 0;
}

static void vmci_transport_free_resources(struct list_head *transport_list)
{
        while (!list_empty(transport_list)) {
                struct vmci_transport *transport =
                    list_first_entry(transport_list, struct vmci_transport,
                                     elem);
                list_del(&transport->elem);

                if (transport->detach_sub_id != VMCI_INVALID_ID) {
                        vmci_event_unsubscribe(transport->detach_sub_id);
                        transport->detach_sub_id = VMCI_INVALID_ID;
                }

                if (!vmci_handle_is_invalid(transport->qp_handle)) {
                        vmci_qpair_detach(&transport->qpair);
                        transport->qp_handle = VMCI_INVALID_HANDLE;
                        transport->produce_size = 0;
                        transport->consume_size = 0;
                }

                kfree(transport);
        }
}

static void vmci_transport_cleanup(struct work_struct *work)
{
        LIST_HEAD(pending);

        spin_lock_bh(&vmci_transport_cleanup_lock);
        list_replace_init(&vmci_transport_cleanup_list, &pending);
        spin_unlock_bh(&vmci_transport_cleanup_lock);
        vmci_transport_free_resources(&pending);
}

static void vmci_transport_destruct(struct vsock_sock *vsk)
{
        /* transport can be NULL if we hit a failure at init() time */
        if (!vmci_trans(vsk))
                return;

        /* Ensure that the detach callback doesn't use the sk/vsk
         * we are about to destruct.
         */
        spin_lock_bh(&vmci_trans(vsk)->lock);
        vmci_trans(vsk)->sk = NULL;
        spin_unlock_bh(&vmci_trans(vsk)->lock);

        if (vmci_trans(vsk)->notify_ops)
                vmci_trans(vsk)->notify_ops->socket_destruct(vsk);

        spin_lock_bh(&vmci_transport_cleanup_lock);
        list_add(&vmci_trans(vsk)->elem, &vmci_transport_cleanup_list);
        spin_unlock_bh(&vmci_transport_cleanup_lock);
        schedule_work(&vmci_transport_cleanup_work);

        vsk->trans = NULL;
}

static void vmci_transport_release(struct vsock_sock *vsk)
{
        vsock_remove_sock(vsk);

        if (!vmci_handle_is_invalid(vmci_trans(vsk)->dg_handle)) {
                vmci_datagram_destroy_handle(vmci_trans(vsk)->dg_handle);
                vmci_trans(vsk)->dg_handle = VMCI_INVALID_HANDLE;
        }
}

static int vmci_transport_dgram_bind(struct vsock_sock *vsk,
                                     struct sockaddr_vm *addr)
{
        u32 port;
        u32 flags;
        int err;

        /* VMCI will select a resource ID for us if we provide
         * VMCI_INVALID_ID.
         */
        port = addr->svm_port == VMADDR_PORT_ANY ?
                        VMCI_INVALID_ID : addr->svm_port;

        if (port <= LAST_RESERVED_PORT && !capable(CAP_NET_BIND_SERVICE))
                return -EACCES;

        flags = addr->svm_cid == VMADDR_CID_ANY ?
                                VMCI_FLAG_ANYCID_DG_HND : 0;

        err = vmci_transport_datagram_create_hnd(port, flags,
                                                 vmci_transport_recv_dgram_cb,
                                                 &vsk->sk,
                                                 &vmci_trans(vsk)->dg_handle);
        if (err < VMCI_SUCCESS)
                return vmci_transport_error_to_vsock_error(err);
        vsock_addr_init(&vsk->local_addr, addr->svm_cid,
                        vmci_trans(vsk)->dg_handle.resource);

        return 0;
}

static int vmci_transport_dgram_enqueue(
        struct vsock_sock *vsk,
        struct sockaddr_vm *remote_addr,
        struct msghdr *msg,
        size_t len)
{
        int err;
        struct vmci_datagram *dg;

        if (len > VMCI_MAX_DG_PAYLOAD_SIZE)
                return -EMSGSIZE;

        if (!vmci_transport_allow_dgram(vsk, remote_addr->svm_cid))
                return -EPERM;

        /* Allocate a buffer for the user's message and our packet header. */
        dg = kmalloc(len + sizeof(*dg), GFP_KERNEL);
        if (!dg)
                return -ENOMEM;

        memcpy_from_msg(VMCI_DG_PAYLOAD(dg), msg, len);

        dg->dst = vmci_make_handle(remote_addr->svm_cid,
                                   remote_addr->svm_port);
        dg->src = vmci_make_handle(vsk->local_addr.svm_cid,
                                   vsk->local_addr.svm_port);
        dg->payload_size = len;

        err = vmci_datagram_send(dg);
        kfree(dg);
        if (err < 0)
                return vmci_transport_error_to_vsock_error(err);

        return err - sizeof(*dg);
}

static int vmci_transport_dgram_dequeue(struct vsock_sock *vsk,
                                        struct msghdr *msg, size_t len,
                                        int flags)
{
        int err;
        int noblock;
        struct vmci_datagram *dg;
        size_t payload_len;
        struct sk_buff *skb;

        noblock = flags & MSG_DONTWAIT;

        if (flags & MSG_OOB || flags & MSG_ERRQUEUE)
                return -EOPNOTSUPP;

        /* Retrieve the head sk_buff from the socket's receive queue. */
        err = 0;
        skb = skb_recv_datagram(&vsk->sk, flags, noblock, &err);
        if (!skb)
                return err;

        dg = (struct vmci_datagram *)skb->data;
        if (!dg)
                /* err is 0, meaning we read zero bytes. */
                goto out;

        payload_len = dg->payload_size;
        /* Ensure the sk_buff matches the payload size claimed in the packet. */
        if (payload_len != skb->len - sizeof(*dg)) {
                err = -EINVAL;
                goto out;
        }

        if (payload_len > len) {
                payload_len = len;
                msg->msg_flags |= MSG_TRUNC;
        }

        /* Place the datagram payload in the user's iovec. */
        err = skb_copy_datagram_msg(skb, sizeof(*dg), msg, payload_len);
        if (err)
                goto out;

        if (msg->msg_name) {
                /* Provide the address of the sender. */
                DECLARE_SOCKADDR(struct sockaddr_vm *, vm_addr, msg->msg_name);
                vsock_addr_init(vm_addr, dg->src.context, dg->src.resource);
                msg->msg_namelen = sizeof(*vm_addr);
        }
        err = payload_len;

out:
        skb_free_datagram(&vsk->sk, skb);
        return err;
}

static bool vmci_transport_dgram_allow(u32 cid, u32 port)
{
        if (cid == VMADDR_CID_HYPERVISOR) {
                /* Registrations of PBRPC Servers do not modify VMX/Hypervisor
                 * state and are allowed.
                 */
                return port == VMCI_UNITY_PBRPC_REGISTER;
        }

        return true;
}

static int vmci_transport_connect(struct vsock_sock *vsk)
{
        int err;
        bool old_pkt_proto = false;
        struct sock *sk = &vsk->sk;

        if (vmci_transport_old_proto_override(&old_pkt_proto) &&
                old_pkt_proto) {
                err = vmci_transport_send_conn_request(
                        sk, vmci_trans(vsk)->queue_pair_size);
                if (err < 0) {
                        sk->sk_state = TCP_CLOSE;
                        return err;
                }
        } else {
                int supported_proto_versions =
                        vmci_transport_new_proto_supported_versions();
                err = vmci_transport_send_conn_request2(
                                sk, vmci_trans(vsk)->queue_pair_size,
                                supported_proto_versions);
                if (err < 0) {
                        sk->sk_state = TCP_CLOSE;
                        return err;
                }

                vsk->sent_request = true;
        }

        return err;
}

static ssize_t vmci_transport_stream_dequeue(
        struct vsock_sock *vsk,
        struct msghdr *msg,
        size_t len,
        int flags)
{
        if (flags & MSG_PEEK)
                return vmci_qpair_peekv(vmci_trans(vsk)->qpair, msg, len, 0);
        else
                return vmci_qpair_dequev(vmci_trans(vsk)->qpair, msg, len, 0);
}

static ssize_t vmci_transport_stream_enqueue(
        struct vsock_sock *vsk,
        struct msghdr *msg,
        size_t len)
{
        return vmci_qpair_enquev(vmci_trans(vsk)->qpair, msg, len, 0);
}

static s64 vmci_transport_stream_has_data(struct vsock_sock *vsk)
{
        return vmci_qpair_consume_buf_ready(vmci_trans(vsk)->qpair);
}

static s64 vmci_transport_stream_has_space(struct vsock_sock *vsk)
{
        return vmci_qpair_produce_free_space(vmci_trans(vsk)->qpair);
}

static u64 vmci_transport_stream_rcvhiwat(struct vsock_sock *vsk)
{
        return vmci_trans(vsk)->consume_size;
}

static bool vmci_transport_stream_is_active(struct vsock_sock *vsk)
{
        return !vmci_handle_is_invalid(vmci_trans(vsk)->qp_handle);
}

static u64 vmci_transport_get_buffer_size(struct vsock_sock *vsk)
{
        return vmci_trans(vsk)->queue_pair_size;
}

static u64 vmci_transport_get_min_buffer_size(struct vsock_sock *vsk)
{
        return vmci_trans(vsk)->queue_pair_min_size;
}

static u64 vmci_transport_get_max_buffer_size(struct vsock_sock *vsk)
{
        return vmci_trans(vsk)->queue_pair_max_size;
}

static void vmci_transport_set_buffer_size(struct vsock_sock *vsk, u64 val)
{
        if (val < vmci_trans(vsk)->queue_pair_min_size)
                vmci_trans(vsk)->queue_pair_min_size = val;
        if (val > vmci_trans(vsk)->queue_pair_max_size)
                vmci_trans(vsk)->queue_pair_max_size = val;
        vmci_trans(vsk)->queue_pair_size = val;
}

static void vmci_transport_set_min_buffer_size(struct vsock_sock *vsk,
                                               u64 val)
{
        if (val > vmci_trans(vsk)->queue_pair_size)
                vmci_trans(vsk)->queue_pair_size = val;
        vmci_trans(vsk)->queue_pair_min_size = val;
}

static void vmci_transport_set_max_buffer_size(struct vsock_sock *vsk,
                                               u64 val)
{
        if (val < vmci_trans(vsk)->queue_pair_size)
                vmci_trans(vsk)->queue_pair_size = val;
        vmci_trans(vsk)->queue_pair_max_size = val;
}

static int vmci_transport_notify_poll_in(
        struct vsock_sock *vsk,
        size_t target,
        bool *data_ready_now)
{
        return vmci_trans(vsk)->notify_ops->poll_in(
                        &vsk->sk, target, data_ready_now);
}

static int vmci_transport_notify_poll_out(
        struct vsock_sock *vsk,
        size_t target,
        bool *space_available_now)
{
        return vmci_trans(vsk)->notify_ops->poll_out(
                        &vsk->sk, target, space_available_now);
}

static int vmci_transport_notify_recv_init(
        struct vsock_sock *vsk,
        size_t target,
        struct vsock_transport_recv_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->recv_init(
                        &vsk->sk, target,
                        (struct vmci_transport_recv_notify_data *)data);
}

static int vmci_transport_notify_recv_pre_block(
        struct vsock_sock *vsk,
        size_t target,
        struct vsock_transport_recv_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->recv_pre_block(
                        &vsk->sk, target,
                        (struct vmci_transport_recv_notify_data *)data);
}

static int vmci_transport_notify_recv_pre_dequeue(
        struct vsock_sock *vsk,
        size_t target,
        struct vsock_transport_recv_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->recv_pre_dequeue(
                        &vsk->sk, target,
                        (struct vmci_transport_recv_notify_data *)data);
}

static int vmci_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 vmci_trans(vsk)->notify_ops->recv_post_dequeue(
                        &vsk->sk, target, copied, data_read,
                        (struct vmci_transport_recv_notify_data *)data);
}

static int vmci_transport_notify_send_init(
        struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->send_init(
                        &vsk->sk,
                        (struct vmci_transport_send_notify_data *)data);
}

static int vmci_transport_notify_send_pre_block(
        struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->send_pre_block(
                        &vsk->sk,
                        (struct vmci_transport_send_notify_data *)data);
}

static int vmci_transport_notify_send_pre_enqueue(
        struct vsock_sock *vsk,
        struct vsock_transport_send_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->send_pre_enqueue(
                        &vsk->sk,
                        (struct vmci_transport_send_notify_data *)data);
}

static int vmci_transport_notify_send_post_enqueue(
        struct vsock_sock *vsk,
        ssize_t written,
        struct vsock_transport_send_notify_data *data)
{
        return vmci_trans(vsk)->notify_ops->send_post_enqueue(
                        &vsk->sk, written,
                        (struct vmci_transport_send_notify_data *)data);
}

static bool vmci_transport_old_proto_override(bool *old_pkt_proto)
{
        if (PROTOCOL_OVERRIDE != -1) {
                if (PROTOCOL_OVERRIDE == 0)
                        *old_pkt_proto = true;
                else
                        *old_pkt_proto = false;

                pr_info("Proto override in use\n");
                return true;
        }

        return false;
}

static bool vmci_transport_proto_to_notify_struct(struct sock *sk,
                                                  u16 *proto,
                                                  bool old_pkt_proto)
{
        struct vsock_sock *vsk = vsock_sk(sk);

        if (old_pkt_proto) {
                if (*proto != VSOCK_PROTO_INVALID) {
                        pr_err("Can't set both an old and new protocol\n");
                        return false;
                }
                vmci_trans(vsk)->notify_ops = &vmci_transport_notify_pkt_ops;
                goto exit;
        }

        switch (*proto) {
        case VSOCK_PROTO_PKT_ON_NOTIFY:
                vmci_trans(vsk)->notify_ops =
                        &vmci_transport_notify_pkt_q_state_ops;
                break;
        default:
                pr_err("Unknown notify protocol version\n");
                return false;
        }

exit:
        vmci_trans(vsk)->notify_ops->socket_init(sk);
        return true;
}

static u16 vmci_transport_new_proto_supported_versions(void)
{
        if (PROTOCOL_OVERRIDE != -1)
                return PROTOCOL_OVERRIDE;

        return VSOCK_PROTO_ALL_SUPPORTED;
}

static u32 vmci_transport_get_local_cid(void)
{
        return vmci_get_context_id();
}

static const struct vsock_transport vmci_transport = {
        .init = vmci_transport_socket_init,
        .destruct = vmci_transport_destruct,
        .release = vmci_transport_release,
        .connect = vmci_transport_connect,
        .dgram_bind = vmci_transport_dgram_bind,
        .dgram_dequeue = vmci_transport_dgram_dequeue,
        .dgram_enqueue = vmci_transport_dgram_enqueue,
        .dgram_allow = vmci_transport_dgram_allow,
        .stream_dequeue = vmci_transport_stream_dequeue,
        .stream_enqueue = vmci_transport_stream_enqueue,
        .stream_has_data = vmci_transport_stream_has_data,
        .stream_has_space = vmci_transport_stream_has_space,
        .stream_rcvhiwat = vmci_transport_stream_rcvhiwat,
        .stream_is_active = vmci_transport_stream_is_active,
        .stream_allow = vmci_transport_stream_allow,
        .notify_poll_in = vmci_transport_notify_poll_in,
        .notify_poll_out = vmci_transport_notify_poll_out,
        .notify_recv_init = vmci_transport_notify_recv_init,
        .notify_recv_pre_block = vmci_transport_notify_recv_pre_block,
        .notify_recv_pre_dequeue = vmci_transport_notify_recv_pre_dequeue,
        .notify_recv_post_dequeue = vmci_transport_notify_recv_post_dequeue,
        .notify_send_init = vmci_transport_notify_send_init,
        .notify_send_pre_block = vmci_transport_notify_send_pre_block,
        .notify_send_pre_enqueue = vmci_transport_notify_send_pre_enqueue,
        .notify_send_post_enqueue = vmci_transport_notify_send_post_enqueue,
        .shutdown = vmci_transport_shutdown,
        .set_buffer_size = vmci_transport_set_buffer_size,
        .set_min_buffer_size = vmci_transport_set_min_buffer_size,
        .set_max_buffer_size = vmci_transport_set_max_buffer_size,
        .get_buffer_size = vmci_transport_get_buffer_size,
        .get_min_buffer_size = vmci_transport_get_min_buffer_size,
        .get_max_buffer_size = vmci_transport_get_max_buffer_size,
        .get_local_cid = vmci_transport_get_local_cid,
};

static int __init vmci_transport_init(void)
{
        int err;

        /* Create the datagram handle that we will use to send and receive all
         * VSocket control messages for this context.
         */
        err = vmci_transport_datagram_create_hnd(VMCI_TRANSPORT_PACKET_RID,
                                                 VMCI_FLAG_ANYCID_DG_HND,
                                                 vmci_transport_recv_stream_cb,
                                                 NULL,
                                                 &vmci_transport_stream_handle);
        if (err < VMCI_SUCCESS) {
                pr_err("Unable to create datagram handle. (%d)\n", err);
                return vmci_transport_error_to_vsock_error(err);
        }

        err = vmci_event_subscribe(VMCI_EVENT_QP_RESUMED,
                                   vmci_transport_qp_resumed_cb,
                                   NULL, &vmci_transport_qp_resumed_sub_id);
        if (err < VMCI_SUCCESS) {
                pr_err("Unable to subscribe to resumed event. (%d)\n", err);
                err = vmci_transport_error_to_vsock_error(err);
                vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
                goto err_destroy_stream_handle;
        }

        err = vsock_core_init(&vmci_transport);
        if (err < 0)
                goto err_unsubscribe;

        return 0;

err_unsubscribe:
        vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
err_destroy_stream_handle:
        vmci_datagram_destroy_handle(vmci_transport_stream_handle);
        return err;
}
module_init(vmci_transport_init);

static void __exit vmci_transport_exit(void)
{
        cancel_work_sync(&vmci_transport_cleanup_work);
        vmci_transport_free_resources(&vmci_transport_cleanup_list);

        if (!vmci_handle_is_invalid(vmci_transport_stream_handle)) {
                if (vmci_datagram_destroy_handle(
                        vmci_transport_stream_handle) != VMCI_SUCCESS)
                        pr_err("Couldn't destroy datagram handle\n");
                vmci_transport_stream_handle = VMCI_INVALID_HANDLE;
        }

        if (vmci_transport_qp_resumed_sub_id != VMCI_INVALID_ID) {
                vmci_event_unsubscribe(vmci_transport_qp_resumed_sub_id);
                vmci_transport_qp_resumed_sub_id = VMCI_INVALID_ID;
        }

        vsock_core_exit();
}
module_exit(vmci_transport_exit);

MODULE_AUTHOR("VMware, Inc.");
MODULE_DESCRIPTION("VMCI transport for Virtual Sockets");
MODULE_VERSION("1.0.5.0-k");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("vmware_vsock");
MODULE_ALIAS_NETPROTO(PF_VSOCK);