// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2010-2011 EIA Electronics,
//                         Pieter Beyens <pieter.beyens@eia.be>
// Copyright (c) 2010-2011 EIA Electronics,
//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
// Copyright (c) 2018 Protonic,
//                         Robin van der Gracht <robin@protonic.nl>
// Copyright (c) 2017-2019 Pengutronix,
//                         Marc Kleine-Budde <kernel@pengutronix.de>
// Copyright (c) 2017-2019 Pengutronix,
//                         Oleksij Rempel <kernel@pengutronix.de>

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/can/can-ml.h>
#include <linux/can/core.h>
#include <linux/can/skb.h>
#include <linux/errqueue.h>
#include <linux/if_arp.h>

#include "j1939-priv.h"

#define J1939_MIN_NAMELEN CAN_REQUIRED_SIZE(struct sockaddr_can, can_addr.j1939)

/* conversion function between struct sock::sk_priority from linux and
 * j1939 priority field
 */
static inline priority_t j1939_prio(u32 sk_priority)
{
        sk_priority = min(sk_priority, 7U);

        return 7 - sk_priority;
}

static inline u32 j1939_to_sk_priority(priority_t prio)
{
        return 7 - prio;
}

/* function to see if pgn is to be evaluated */
static inline bool j1939_pgn_is_valid(pgn_t pgn)
{
        return pgn <= J1939_PGN_MAX;
}

/* test function to avoid non-zero DA placeholder for pdu1 pgn's */
static inline bool j1939_pgn_is_clean_pdu(pgn_t pgn)
{
        if (j1939_pgn_is_pdu1(pgn))
                return !(pgn & 0xff);
        else
                return true;
}

static inline void j1939_sock_pending_add(struct sock *sk)
{
        struct j1939_sock *jsk = j1939_sk(sk);

        atomic_inc(&jsk->skb_pending);
}

static int j1939_sock_pending_get(struct sock *sk)
{
        struct j1939_sock *jsk = j1939_sk(sk);

        return atomic_read(&jsk->skb_pending);
}

void j1939_sock_pending_del(struct sock *sk)
{
        struct j1939_sock *jsk = j1939_sk(sk);

        /* atomic_dec_return returns the new value */
        if (!atomic_dec_return(&jsk->skb_pending))
                wake_up(&jsk->waitq);   /* no pending SKB's */
}

static void j1939_jsk_add(struct j1939_priv *priv, struct j1939_sock *jsk)
{
        jsk->state |= J1939_SOCK_BOUND;
        j1939_priv_get(priv);

        spin_lock_bh(&priv->j1939_socks_lock);
        list_add_tail(&jsk->list, &priv->j1939_socks);
        spin_unlock_bh(&priv->j1939_socks_lock);
}

static void j1939_jsk_del(struct j1939_priv *priv, struct j1939_sock *jsk)
{
        spin_lock_bh(&priv->j1939_socks_lock);
        list_del_init(&jsk->list);
        spin_unlock_bh(&priv->j1939_socks_lock);

        j1939_priv_put(priv);
        jsk->state &= ~J1939_SOCK_BOUND;
}

static bool j1939_sk_queue_session(struct j1939_session *session)
{
        struct j1939_sock *jsk = j1939_sk(session->sk);
        bool empty;

        spin_lock_bh(&jsk->sk_session_queue_lock);
        empty = list_empty(&jsk->sk_session_queue);
        j1939_session_get(session);
        list_add_tail(&session->sk_session_queue_entry, &jsk->sk_session_queue);
        spin_unlock_bh(&jsk->sk_session_queue_lock);
        j1939_sock_pending_add(&jsk->sk);

        return empty;
}

static struct
j1939_session *j1939_sk_get_incomplete_session(struct j1939_sock *jsk)
{
        struct j1939_session *session = NULL;

        spin_lock_bh(&jsk->sk_session_queue_lock);
        if (!list_empty(&jsk->sk_session_queue)) {
                session = list_last_entry(&jsk->sk_session_queue,
                                          struct j1939_session,
                                          sk_session_queue_entry);
                if (session->total_queued_size == session->total_message_size)
                        session = NULL;
                else
                        j1939_session_get(session);
        }
        spin_unlock_bh(&jsk->sk_session_queue_lock);

        return session;
}

static void j1939_sk_queue_drop_all(struct j1939_priv *priv,
                                    struct j1939_sock *jsk, int err)
{
        struct j1939_session *session, *tmp;

        netdev_dbg(priv->ndev, "%s: err: %i\n", __func__, err);
        spin_lock_bh(&jsk->sk_session_queue_lock);
        list_for_each_entry_safe(session, tmp, &jsk->sk_session_queue,
                                 sk_session_queue_entry) {
                list_del_init(&session->sk_session_queue_entry);
                session->err = err;
                j1939_session_put(session);
        }
        spin_unlock_bh(&jsk->sk_session_queue_lock);
}

static void j1939_sk_queue_activate_next_locked(struct j1939_session *session)
{
        struct j1939_sock *jsk;
        struct j1939_session *first;
        int err;

        /* RX-Session don't have a socket (yet) */
        if (!session->sk)
                return;

        jsk = j1939_sk(session->sk);
        lockdep_assert_held(&jsk->sk_session_queue_lock);

        err = session->err;

        first = list_first_entry_or_null(&jsk->sk_session_queue,
                                         struct j1939_session,
                                         sk_session_queue_entry);

        /* Some else has already activated the next session */
        if (first != session)
                return;

activate_next:
        list_del_init(&first->sk_session_queue_entry);
        j1939_session_put(first);
        first = list_first_entry_or_null(&jsk->sk_session_queue,
                                         struct j1939_session,
                                         sk_session_queue_entry);
        if (!first)
                return;

        if (WARN_ON_ONCE(j1939_session_activate(first))) {
                first->err = -EBUSY;
                goto activate_next;
        } else {
                /* Give receiver some time (arbitrary chosen) to recover */
                int time_ms = 0;

                if (err)
                        time_ms = 10 + prandom_u32_max(16);

                j1939_tp_schedule_txtimer(first, time_ms);
        }
}

void j1939_sk_queue_activate_next(struct j1939_session *session)
{
        struct j1939_sock *jsk;

        if (!session->sk)
                return;

        jsk = j1939_sk(session->sk);

        spin_lock_bh(&jsk->sk_session_queue_lock);
        j1939_sk_queue_activate_next_locked(session);
        spin_unlock_bh(&jsk->sk_session_queue_lock);
}

static bool j1939_sk_match_dst(struct j1939_sock *jsk,
                               const struct j1939_sk_buff_cb *skcb)
{
        if ((jsk->state & J1939_SOCK_PROMISC))
                return true;

        /* Destination address filter */
        if (jsk->addr.src_name && skcb->addr.dst_name) {
                if (jsk->addr.src_name != skcb->addr.dst_name)
                        return false;
        } else {
                /* receive (all sockets) if
                 * - all packages that match our bind() address
                 * - all broadcast on a socket if SO_BROADCAST
                 *   is set
                 */
                if (j1939_address_is_unicast(skcb->addr.da)) {
                        if (jsk->addr.sa != skcb->addr.da)
                                return false;
                } else if (!sock_flag(&jsk->sk, SOCK_BROADCAST)) {
                        /* receiving broadcast without SO_BROADCAST
                         * flag is not allowed
                         */
                        return false;
                }
        }

        /* Source address filter */
        if (jsk->state & J1939_SOCK_CONNECTED) {
                /* receive (all sockets) if
                 * - all packages that match our connect() name or address
                 */
                if (jsk->addr.dst_name && skcb->addr.src_name) {
                        if (jsk->addr.dst_name != skcb->addr.src_name)
                                return false;
                } else {
                        if (jsk->addr.da != skcb->addr.sa)
                                return false;
                }
        }

        /* PGN filter */
        if (j1939_pgn_is_valid(jsk->pgn_rx_filter) &&
            jsk->pgn_rx_filter != skcb->addr.pgn)
                return false;

        return true;
}

/* matches skb control buffer (addr) with a j1939 filter */
static bool j1939_sk_match_filter(struct j1939_sock *jsk,
                                  const struct j1939_sk_buff_cb *skcb)
{
        const struct j1939_filter *f = jsk->filters;
        int nfilter = jsk->nfilters;

        if (!nfilter)
                /* receive all when no filters are assigned */
                return true;

        for (; nfilter; ++f, --nfilter) {
                if ((skcb->addr.pgn & f->pgn_mask) != f->pgn)
                        continue;
                if ((skcb->addr.sa & f->addr_mask) != f->addr)
                        continue;
                if ((skcb->addr.src_name & f->name_mask) != f->name)
                        continue;
                return true;
        }
        return false;
}

static bool j1939_sk_recv_match_one(struct j1939_sock *jsk,
                                    const struct j1939_sk_buff_cb *skcb)
{
        if (!(jsk->state & J1939_SOCK_BOUND))
                return false;

        if (!j1939_sk_match_dst(jsk, skcb))
                return false;

        if (!j1939_sk_match_filter(jsk, skcb))
                return false;

        return true;
}

static void j1939_sk_recv_one(struct j1939_sock *jsk, struct sk_buff *oskb)
{
        const struct j1939_sk_buff_cb *oskcb = j1939_skb_to_cb(oskb);
        struct j1939_sk_buff_cb *skcb;
        struct sk_buff *skb;

        if (oskb->sk == &jsk->sk)
                return;

        if (!j1939_sk_recv_match_one(jsk, oskcb))
                return;

        skb = skb_clone(oskb, GFP_ATOMIC);
        if (!skb) {
                pr_warn("skb clone failed\n");
                return;
        }
        can_skb_set_owner(skb, oskb->sk);

        skcb = j1939_skb_to_cb(skb);
        skcb->msg_flags &= ~(MSG_DONTROUTE);
        if (skb->sk)
                skcb->msg_flags |= MSG_DONTROUTE;

        if (sock_queue_rcv_skb(&jsk->sk, skb) < 0)
                kfree_skb(skb);
}

bool j1939_sk_recv_match(struct j1939_priv *priv, struct j1939_sk_buff_cb *skcb)
{
        struct j1939_sock *jsk;
        bool match = false;

        spin_lock_bh(&priv->j1939_socks_lock);
        list_for_each_entry(jsk, &priv->j1939_socks, list) {
                match = j1939_sk_recv_match_one(jsk, skcb);
                if (match)
                        break;
        }
        spin_unlock_bh(&priv->j1939_socks_lock);

        return match;
}

void j1939_sk_recv(struct j1939_priv *priv, struct sk_buff *skb)
{
        struct j1939_sock *jsk;

        spin_lock_bh(&priv->j1939_socks_lock);
        list_for_each_entry(jsk, &priv->j1939_socks, list) {
                j1939_sk_recv_one(jsk, skb);
        }
        spin_unlock_bh(&priv->j1939_socks_lock);
}

static void j1939_sk_sock_destruct(struct sock *sk)
{
        struct j1939_sock *jsk = j1939_sk(sk);

        /* This function will be called by the generic networking code, when
         * the socket is ultimately closed (sk->sk_destruct).
         *
         * The race between
         * - processing a received CAN frame
         *   (can_receive -> j1939_can_recv)
         *   and accessing j1939_priv
         * ... and ...
         * - closing a socket
         *   (j1939_can_rx_unregister -> can_rx_unregister)
         *   and calling the final j1939_priv_put()
         *
         * is avoided by calling the final j1939_priv_put() from this
         * RCU deferred cleanup call.
         */
        if (jsk->priv) {
                j1939_priv_put(jsk->priv);
                jsk->priv = NULL;
        }

        /* call generic CAN sock destruct */
        can_sock_destruct(sk);
}

static int j1939_sk_init(struct sock *sk)
{
        struct j1939_sock *jsk = j1939_sk(sk);

        /* Ensure that "sk" is first member in "struct j1939_sock", so that we
         * can skip it during memset().
         */
        BUILD_BUG_ON(offsetof(struct j1939_sock, sk) != 0);
        memset((void *)jsk + sizeof(jsk->sk), 0x0,
               sizeof(*jsk) - sizeof(jsk->sk));

        INIT_LIST_HEAD(&jsk->list);
        init_waitqueue_head(&jsk->waitq);
        jsk->sk.sk_priority = j1939_to_sk_priority(6);
        jsk->sk.sk_reuse = 1; /* per default */
        jsk->addr.sa = J1939_NO_ADDR;
        jsk->addr.da = J1939_NO_ADDR;
        jsk->addr.pgn = J1939_NO_PGN;
        jsk->pgn_rx_filter = J1939_NO_PGN;
        atomic_set(&jsk->skb_pending, 0);
        spin_lock_init(&jsk->sk_session_queue_lock);
        INIT_LIST_HEAD(&jsk->sk_session_queue);

        /* j1939_sk_sock_destruct() depends on SOCK_RCU_FREE flag */
        sock_set_flag(sk, SOCK_RCU_FREE);
        sk->sk_destruct = j1939_sk_sock_destruct;
        sk->sk_protocol = CAN_J1939;

        return 0;
}

static int j1939_sk_sanity_check(struct sockaddr_can *addr, int len)
{
        if (!addr)
                return -EDESTADDRREQ;
        if (len < J1939_MIN_NAMELEN)
                return -EINVAL;
        if (addr->can_family != AF_CAN)
                return -EINVAL;
        if (!addr->can_ifindex)
                return -ENODEV;
        if (j1939_pgn_is_valid(addr->can_addr.j1939.pgn) &&
            !j1939_pgn_is_clean_pdu(addr->can_addr.j1939.pgn))
                return -EINVAL;

        return 0;
}

static int j1939_sk_bind(struct socket *sock, struct sockaddr *uaddr, int len)
{
        struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
        struct j1939_sock *jsk = j1939_sk(sock->sk);
        struct j1939_priv *priv;
        struct sock *sk;
        struct net *net;
        int ret = 0;

        ret = j1939_sk_sanity_check(addr, len);
        if (ret)
                return ret;

        lock_sock(sock->sk);

        priv = jsk->priv;
        sk = sock->sk;
        net = sock_net(sk);

        /* Already bound to an interface? */
        if (jsk->state & J1939_SOCK_BOUND) {
                /* A re-bind() to a different interface is not
                 * supported.
                 */
                if (jsk->ifindex != addr->can_ifindex) {
                        ret = -EINVAL;
                        goto out_release_sock;
                }

                /* drop old references */
                j1939_jsk_del(priv, jsk);
                j1939_local_ecu_put(priv, jsk->addr.src_name, jsk->addr.sa);
        } else {
                struct can_ml_priv *can_ml;
                struct net_device *ndev;

                ndev = dev_get_by_index(net, addr->can_ifindex);
                if (!ndev) {
                        ret = -ENODEV;
                        goto out_release_sock;
                }

                can_ml = can_get_ml_priv(ndev);
                if (!can_ml) {
                        dev_put(ndev);
                        ret = -ENODEV;
                        goto out_release_sock;
                }

                if (!(ndev->flags & IFF_UP)) {
                        dev_put(ndev);
                        ret = -ENETDOWN;
                        goto out_release_sock;
                }

                priv = j1939_netdev_start(ndev);
                dev_put(ndev);
                if (IS_ERR(priv)) {
                        ret = PTR_ERR(priv);
                        goto out_release_sock;
                }

                jsk->ifindex = addr->can_ifindex;

                /* the corresponding j1939_priv_put() is called via
                 * sk->sk_destruct, which points to j1939_sk_sock_destruct()
                 */
                j1939_priv_get(priv);
                jsk->priv = priv;
        }

        /* set default transmit pgn */
        if (j1939_pgn_is_valid(addr->can_addr.j1939.pgn))
                jsk->pgn_rx_filter = addr->can_addr.j1939.pgn;
        jsk->addr.src_name = addr->can_addr.j1939.name;
        jsk->addr.sa = addr->can_addr.j1939.addr;

        /* get new references */
        ret = j1939_local_ecu_get(priv, jsk->addr.src_name, jsk->addr.sa);
        if (ret) {
                j1939_netdev_stop(priv);
                goto out_release_sock;
        }

        j1939_jsk_add(priv, jsk);

 out_release_sock: /* fall through */
        release_sock(sock->sk);

        return ret;
}

static int j1939_sk_connect(struct socket *sock, struct sockaddr *uaddr,
                            int len, int flags)
{
        struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
        struct j1939_sock *jsk = j1939_sk(sock->sk);
        int ret = 0;

        ret = j1939_sk_sanity_check(addr, len);
        if (ret)
                return ret;

        lock_sock(sock->sk);

        /* bind() before connect() is mandatory */
        if (!(jsk->state & J1939_SOCK_BOUND)) {
                ret = -EINVAL;
                goto out_release_sock;
        }

        /* A connect() to a different interface is not supported. */
        if (jsk->ifindex != addr->can_ifindex) {
                ret = -EINVAL;
                goto out_release_sock;
        }

        if (!addr->can_addr.j1939.name &&
            addr->can_addr.j1939.addr == J1939_NO_ADDR &&
            !sock_flag(&jsk->sk, SOCK_BROADCAST)) {
                /* broadcast, but SO_BROADCAST not set */
                ret = -EACCES;
                goto out_release_sock;
        }

        jsk->addr.dst_name = addr->can_addr.j1939.name;
        jsk->addr.da = addr->can_addr.j1939.addr;

        if (j1939_pgn_is_valid(addr->can_addr.j1939.pgn))
                jsk->addr.pgn = addr->can_addr.j1939.pgn;

        jsk->state |= J1939_SOCK_CONNECTED;

 out_release_sock: /* fall through */
        release_sock(sock->sk);

        return ret;
}

static void j1939_sk_sock2sockaddr_can(struct sockaddr_can *addr,
                                       const struct j1939_sock *jsk, int peer)
{
        /* There are two holes (2 bytes and 3 bytes) to clear to avoid
         * leaking kernel information to user space.
         */
        memset(addr, 0, J1939_MIN_NAMELEN);

        addr->can_family = AF_CAN;
        addr->can_ifindex = jsk->ifindex;
        addr->can_addr.j1939.pgn = jsk->addr.pgn;
        if (peer) {
                addr->can_addr.j1939.name = jsk->addr.dst_name;
                addr->can_addr.j1939.addr = jsk->addr.da;
        } else {
                addr->can_addr.j1939.name = jsk->addr.src_name;
                addr->can_addr.j1939.addr = jsk->addr.sa;
        }
}

static int j1939_sk_getname(struct socket *sock, struct sockaddr *uaddr,
                            int peer)
{
        struct sockaddr_can *addr = (struct sockaddr_can *)uaddr;
        struct sock *sk = sock->sk;
        struct j1939_sock *jsk = j1939_sk(sk);
        int ret = 0;

        lock_sock(sk);

        if (peer && !(jsk->state & J1939_SOCK_CONNECTED)) {
                ret = -EADDRNOTAVAIL;
                goto failure;
        }

        j1939_sk_sock2sockaddr_can(addr, jsk, peer);
        ret = J1939_MIN_NAMELEN;

 failure:
        release_sock(sk);

        return ret;
}

static int j1939_sk_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        struct j1939_sock *jsk;

        if (!sk)
                return 0;

        lock_sock(sk);
        jsk = j1939_sk(sk);

        if (jsk->state & J1939_SOCK_BOUND) {
                struct j1939_priv *priv = jsk->priv;

                if (wait_event_interruptible(jsk->waitq,
                                             !j1939_sock_pending_get(&jsk->sk))) {
                        j1939_cancel_active_session(priv, sk);
                        j1939_sk_queue_drop_all(priv, jsk, ESHUTDOWN);
                }

                j1939_jsk_del(priv, jsk);

                j1939_local_ecu_put(priv, jsk->addr.src_name,
                                    jsk->addr.sa);

                j1939_netdev_stop(priv);
        }

        kfree(jsk->filters);
        sock_orphan(sk);
        sock->sk = NULL;

        release_sock(sk);
        sock_put(sk);

        return 0;
}

static int j1939_sk_setsockopt_flag(struct j1939_sock *jsk, sockptr_t optval,
                                    unsigned int optlen, int flag)
{
        int tmp;

        if (optlen != sizeof(tmp))
                return -EINVAL;
        if (copy_from_sockptr(&tmp, optval, optlen))
                return -EFAULT;
        lock_sock(&jsk->sk);
        if (tmp)
                jsk->state |= flag;
        else
                jsk->state &= ~flag;
        release_sock(&jsk->sk);
        return tmp;
}

static int j1939_sk_setsockopt(struct socket *sock, int level, int optname,
                               sockptr_t optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;
        struct j1939_sock *jsk = j1939_sk(sk);
        int tmp, count = 0, ret = 0;
        struct j1939_filter *filters = NULL, *ofilters;

        if (level != SOL_CAN_J1939)
                return -EINVAL;

        switch (optname) {
        case SO_J1939_FILTER:
                if (!sockptr_is_null(optval) && optlen != 0) {
                        struct j1939_filter *f;
                        int c;

                        if (optlen % sizeof(*filters) != 0)
                                return -EINVAL;

                        if (optlen > J1939_FILTER_MAX *
                            sizeof(struct j1939_filter))
                                return -EINVAL;

                        count = optlen / sizeof(*filters);
                        filters = memdup_sockptr(optval, optlen);
                        if (IS_ERR(filters))
                                return PTR_ERR(filters);

                        for (f = filters, c = count; c; f++, c--) {
                                f->name &= f->name_mask;
                                f->pgn &= f->pgn_mask;
                                f->addr &= f->addr_mask;
                        }
                }

                lock_sock(&jsk->sk);
                ofilters = jsk->filters;
                jsk->filters = filters;
                jsk->nfilters = count;
                release_sock(&jsk->sk);
                kfree(ofilters);
                return 0;
        case SO_J1939_PROMISC:
                return j1939_sk_setsockopt_flag(jsk, optval, optlen,
                                                J1939_SOCK_PROMISC);
        case SO_J1939_ERRQUEUE:
                ret = j1939_sk_setsockopt_flag(jsk, optval, optlen,
                                               J1939_SOCK_ERRQUEUE);
                if (ret < 0)
                        return ret;

                if (!(jsk->state & J1939_SOCK_ERRQUEUE))
                        skb_queue_purge(&sk->sk_error_queue);
                return ret;
        case SO_J1939_SEND_PRIO:
                if (optlen != sizeof(tmp))
                        return -EINVAL;
                if (copy_from_sockptr(&tmp, optval, optlen))
                        return -EFAULT;
                if (tmp < 0 || tmp > 7)
                        return -EDOM;
                if (tmp < 2 && !capable(CAP_NET_ADMIN))
                        return -EPERM;
                lock_sock(&jsk->sk);
                jsk->sk.sk_priority = j1939_to_sk_priority(tmp);
                release_sock(&jsk->sk);
                return 0;
        default:
                return -ENOPROTOOPT;
        }
}

static int j1939_sk_getsockopt(struct socket *sock, int level, int optname,
                               char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;
        struct j1939_sock *jsk = j1939_sk(sk);
        int ret, ulen;
        /* set defaults for using 'int' properties */
        int tmp = 0;
        int len = sizeof(tmp);
        void *val = &tmp;

        if (level != SOL_CAN_J1939)
                return -EINVAL;
        if (get_user(ulen, optlen))
                return -EFAULT;
        if (ulen < 0)
                return -EINVAL;

        lock_sock(&jsk->sk);
        switch (optname) {
        case SO_J1939_PROMISC:
                tmp = (jsk->state & J1939_SOCK_PROMISC) ? 1 : 0;
                break;
        case SO_J1939_ERRQUEUE:
                tmp = (jsk->state & J1939_SOCK_ERRQUEUE) ? 1 : 0;
                break;
        case SO_J1939_SEND_PRIO:
                tmp = j1939_prio(jsk->sk.sk_priority);
                break;
        default:
                ret = -ENOPROTOOPT;
                goto no_copy;
        }

        /* copy to user, based on 'len' & 'val'
         * but most sockopt's are 'int' properties, and have 'len' & 'val'
         * left unchanged, but instead modified 'tmp'
         */
        if (len > ulen)
                ret = -EFAULT;
        else if (put_user(len, optlen))
                ret = -EFAULT;
        else if (copy_to_user(optval, val, len))
                ret = -EFAULT;
        else
                ret = 0;
 no_copy:
        release_sock(&jsk->sk);
        return ret;
}

static int j1939_sk_recvmsg(struct socket *sock, struct msghdr *msg,
                            size_t size, int flags)
{
        struct sock *sk = sock->sk;
        struct sk_buff *skb;
        struct j1939_sk_buff_cb *skcb;
        int ret = 0;

        if (flags & ~(MSG_DONTWAIT | MSG_ERRQUEUE))
                return -EINVAL;

        if (flags & MSG_ERRQUEUE)
                return sock_recv_errqueue(sock->sk, msg, size, SOL_CAN_J1939,
                                          SCM_J1939_ERRQUEUE);

        skb = skb_recv_datagram(sk, flags, 0, &ret);
        if (!skb)
                return ret;

        if (size < skb->len)
                msg->msg_flags |= MSG_TRUNC;
        else
                size = skb->len;

        ret = memcpy_to_msg(msg, skb->data, size);
        if (ret < 0) {
                skb_free_datagram(sk, skb);
                return ret;
        }

        skcb = j1939_skb_to_cb(skb);
        if (j1939_address_is_valid(skcb->addr.da))
                put_cmsg(msg, SOL_CAN_J1939, SCM_J1939_DEST_ADDR,
                         sizeof(skcb->addr.da), &skcb->addr.da);

        if (skcb->addr.dst_name)
                put_cmsg(msg, SOL_CAN_J1939, SCM_J1939_DEST_NAME,
                         sizeof(skcb->addr.dst_name), &skcb->addr.dst_name);

        put_cmsg(msg, SOL_CAN_J1939, SCM_J1939_PRIO,
                 sizeof(skcb->priority), &skcb->priority);

        if (msg->msg_name) {
                struct sockaddr_can *paddr = msg->msg_name;

                msg->msg_namelen = J1939_MIN_NAMELEN;
                memset(msg->msg_name, 0, msg->msg_namelen);
                paddr->can_family = AF_CAN;
                paddr->can_ifindex = skb->skb_iif;
                paddr->can_addr.j1939.name = skcb->addr.src_name;
                paddr->can_addr.j1939.addr = skcb->addr.sa;
                paddr->can_addr.j1939.pgn = skcb->addr.pgn;
        }

        sock_recv_ts_and_drops(msg, sk, skb);
        msg->msg_flags |= skcb->msg_flags;
        skb_free_datagram(sk, skb);

        return size;
}

static struct sk_buff *j1939_sk_alloc_skb(struct net_device *ndev,
                                          struct sock *sk,
                                          struct msghdr *msg, size_t size,
                                          int *errcode)
{
        struct j1939_sock *jsk = j1939_sk(sk);
        struct j1939_sk_buff_cb *skcb;
        struct sk_buff *skb;
        int ret;

        skb = sock_alloc_send_skb(sk,
                                  size +
                                  sizeof(struct can_frame) -
                                  sizeof(((struct can_frame *)NULL)->data) +
                                  sizeof(struct can_skb_priv),
                                  msg->msg_flags & MSG_DONTWAIT, &ret);
        if (!skb)
                goto failure;

        can_skb_reserve(skb);
        can_skb_prv(skb)->ifindex = ndev->ifindex;
        can_skb_prv(skb)->skbcnt = 0;
        skb_reserve(skb, offsetof(struct can_frame, data));

        ret = memcpy_from_msg(skb_put(skb, size), msg, size);
        if (ret < 0)
                goto free_skb;

        skb->dev = ndev;

        skcb = j1939_skb_to_cb(skb);
        memset(skcb, 0, sizeof(*skcb));
        skcb->addr = jsk->addr;
        skcb->priority = j1939_prio(sk->sk_priority);

        if (msg->msg_name) {
                struct sockaddr_can *addr = msg->msg_name;

                if (addr->can_addr.j1939.name ||
                    addr->can_addr.j1939.addr != J1939_NO_ADDR) {
                        skcb->addr.dst_name = addr->can_addr.j1939.name;
                        skcb->addr.da = addr->can_addr.j1939.addr;
                }
                if (j1939_pgn_is_valid(addr->can_addr.j1939.pgn))
                        skcb->addr.pgn = addr->can_addr.j1939.pgn;
        }

        *errcode = ret;
        return skb;

free_skb:
        kfree_skb(skb);
failure:
        *errcode = ret;
        return NULL;
}

static size_t j1939_sk_opt_stats_get_size(enum j1939_sk_errqueue_type type)
{
        switch (type) {
        case J1939_ERRQUEUE_RX_RTS:
                return
                        nla_total_size(sizeof(u32)) + /* J1939_NLA_TOTAL_SIZE */
                        nla_total_size(sizeof(u32)) + /* J1939_NLA_PGN */
                        nla_total_size(sizeof(u64)) + /* J1939_NLA_SRC_NAME */
                        nla_total_size(sizeof(u64)) + /* J1939_NLA_DEST_NAME */
                        nla_total_size(sizeof(u8)) +  /* J1939_NLA_SRC_ADDR */
                        nla_total_size(sizeof(u8)) +  /* J1939_NLA_DEST_ADDR */
                        0;
        default:
                return
                        nla_total_size(sizeof(u32)) + /* J1939_NLA_BYTES_ACKED */
                        0;
        }
}

static struct sk_buff *
j1939_sk_get_timestamping_opt_stats(struct j1939_session *session,
                                    enum j1939_sk_errqueue_type type)
{
        struct sk_buff *stats;
        u32 size;

        stats = alloc_skb(j1939_sk_opt_stats_get_size(type), GFP_ATOMIC);
        if (!stats)
                return NULL;

        if (session->skcb.addr.type == J1939_SIMPLE)
                size = session->total_message_size;
        else
                size = min(session->pkt.tx_acked * 7,
                           session->total_message_size);

        switch (type) {
        case J1939_ERRQUEUE_RX_RTS:
                nla_put_u32(stats, J1939_NLA_TOTAL_SIZE,
                            session->total_message_size);
                nla_put_u32(stats, J1939_NLA_PGN,
                            session->skcb.addr.pgn);
                nla_put_u64_64bit(stats, J1939_NLA_SRC_NAME,
                                  session->skcb.addr.src_name, J1939_NLA_PAD);
                nla_put_u64_64bit(stats, J1939_NLA_DEST_NAME,
                                  session->skcb.addr.dst_name, J1939_NLA_PAD);
                nla_put_u8(stats, J1939_NLA_SRC_ADDR,
                           session->skcb.addr.sa);
                nla_put_u8(stats, J1939_NLA_DEST_ADDR,
                           session->skcb.addr.da);
                break;
        default:
                nla_put_u32(stats, J1939_NLA_BYTES_ACKED, size);
        }

        return stats;
}

static void __j1939_sk_errqueue(struct j1939_session *session, struct sock *sk,
                                enum j1939_sk_errqueue_type type)
{
        struct j1939_priv *priv = session->priv;
        struct j1939_sock *jsk;
        struct sock_exterr_skb *serr;
        struct sk_buff *skb;
        char *state = "UNK";
        int err;

        jsk = j1939_sk(sk);

        if (!(jsk->state & J1939_SOCK_ERRQUEUE))
                return;

        switch (type) {
        case J1939_ERRQUEUE_TX_ACK:
                if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_ACK))
                        return;
                break;
        case J1939_ERRQUEUE_TX_SCHED:
                if (!(sk->sk_tsflags & SOF_TIMESTAMPING_TX_SCHED))
                        return;
                break;
        case J1939_ERRQUEUE_TX_ABORT:
                break;
        case J1939_ERRQUEUE_RX_RTS:
                fallthrough;
        case J1939_ERRQUEUE_RX_DPO:
                fallthrough;
        case J1939_ERRQUEUE_RX_ABORT:
                if (!(sk->sk_tsflags & SOF_TIMESTAMPING_RX_SOFTWARE))
                        return;
                break;
        default:

                netdev_err(priv->ndev, "Unknown errqueue type %i\n", type);
        }

        skb = j1939_sk_get_timestamping_opt_stats(session, type);
        if (!skb)
                return;

        skb->tstamp = ktime_get_real();

        BUILD_BUG_ON(sizeof(struct sock_exterr_skb) > sizeof(skb->cb));

        serr = SKB_EXT_ERR(skb);
        memset(serr, 0, sizeof(*serr));
        switch (type) {
        case J1939_ERRQUEUE_TX_ACK:
                serr->ee.ee_errno = ENOMSG;
                serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
                serr->ee.ee_info = SCM_TSTAMP_ACK;
                state = "TX ACK";
                break;
        case J1939_ERRQUEUE_TX_SCHED:
                serr->ee.ee_errno = ENOMSG;
                serr->ee.ee_origin = SO_EE_ORIGIN_TIMESTAMPING;
                serr->ee.ee_info = SCM_TSTAMP_SCHED;
                state = "TX SCH";
                break;
        case J1939_ERRQUEUE_TX_ABORT:
                serr->ee.ee_errno = session->err;
                serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
                serr->ee.ee_info = J1939_EE_INFO_TX_ABORT;
                state = "TX ABT";
                break;
        case J1939_ERRQUEUE_RX_RTS:
                serr->ee.ee_errno = ENOMSG;
                serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
                serr->ee.ee_info = J1939_EE_INFO_RX_RTS;
                state = "RX RTS";
                break;
        case J1939_ERRQUEUE_RX_DPO:
                serr->ee.ee_errno = ENOMSG;
                serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
                serr->ee.ee_info = J1939_EE_INFO_RX_DPO;
                state = "RX DPO";
                break;
        case J1939_ERRQUEUE_RX_ABORT:
                serr->ee.ee_errno = session->err;
                serr->ee.ee_origin = SO_EE_ORIGIN_LOCAL;
                serr->ee.ee_info = J1939_EE_INFO_RX_ABORT;
                state = "RX ABT";
                break;
        }

        serr->opt_stats = true;
        if (sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
                serr->ee.ee_data = session->tskey;

        netdev_dbg(session->priv->ndev, "%s: 0x%p tskey: %i, state: %s\n",
                   __func__, session, session->tskey, state);
        err = sock_queue_err_skb(sk, skb);

        if (err)
                kfree_skb(skb);
};

void j1939_sk_errqueue(struct j1939_session *session,
                       enum j1939_sk_errqueue_type type)
{
        struct j1939_priv *priv = session->priv;
        struct j1939_sock *jsk;

        if (session->sk) {
                /* send TX notifications to the socket of origin  */
                __j1939_sk_errqueue(session, session->sk, type);
                return;
        }

        /* spread RX notifications to all sockets subscribed to this session */
        spin_lock_bh(&priv->j1939_socks_lock);
        list_for_each_entry(jsk, &priv->j1939_socks, list) {
                if (j1939_sk_recv_match_one(jsk, &session->skcb))
                        __j1939_sk_errqueue(session, &jsk->sk, type);
        }
        spin_unlock_bh(&priv->j1939_socks_lock);
};

void j1939_sk_send_loop_abort(struct sock *sk, int err)
{
        sk->sk_err = err;

        sk_error_report(sk);
}

static int j1939_sk_send_loop(struct j1939_priv *priv,  struct sock *sk,
                              struct msghdr *msg, size_t size)

{
        struct j1939_sock *jsk = j1939_sk(sk);
        struct j1939_session *session = j1939_sk_get_incomplete_session(jsk);
        struct sk_buff *skb;
        size_t segment_size, todo_size;
        int ret = 0;

        if (session &&
            session->total_message_size != session->total_queued_size + size) {
                j1939_session_put(session);
                return -EIO;
        }

        todo_size = size;

        while (todo_size) {
                struct j1939_sk_buff_cb *skcb;

                segment_size = min_t(size_t, J1939_MAX_TP_PACKET_SIZE,
                                     todo_size);

                /* Allocate skb for one segment */
                skb = j1939_sk_alloc_skb(priv->ndev, sk, msg, segment_size,
                                         &ret);
                if (ret)
                        break;

                skcb = j1939_skb_to_cb(skb);

                if (!session) {
                        /* at this point the size should be full size
                         * of the session
                         */
                        skcb->offset = 0;
                        session = j1939_tp_send(priv, skb, size);
                        if (IS_ERR(session)) {
                                ret = PTR_ERR(session);
                                goto kfree_skb;
                        }
                        if (j1939_sk_queue_session(session)) {
                                /* try to activate session if we a
                                 * fist in the queue
                                 */
                                if (!j1939_session_activate(session)) {
                                        j1939_tp_schedule_txtimer(session, 0);
                                } else {
                                        ret = -EBUSY;
                                        session->err = ret;
                                        j1939_sk_queue_drop_all(priv, jsk,
                                                                EBUSY);
                                        break;
                                }
                        }
                } else {
                        skcb->offset = session->total_queued_size;
                        j1939_session_skb_queue(session, skb);
                }

                todo_size -= segment_size;
                session->total_queued_size += segment_size;
        }

        switch (ret) {
        case 0: /* OK */
                if (todo_size)
                        netdev_warn(priv->ndev,
                                    "no error found and not completely queued?! %zu\n",
                                    todo_size);
                ret = size;
                break;
        case -ERESTARTSYS:
                ret = -EINTR;
                fallthrough;
        case -EAGAIN: /* OK */
                if (todo_size != size)
                        ret = size - todo_size;
                break;
        default: /* ERROR */
                break;
        }

        if (session)
                j1939_session_put(session);

        return ret;

 kfree_skb:
        kfree_skb(skb);
        return ret;
}

static int j1939_sk_sendmsg(struct socket *sock, struct msghdr *msg,
                            size_t size)
{
        struct sock *sk = sock->sk;
        struct j1939_sock *jsk = j1939_sk(sk);
        struct j1939_priv *priv;
        int ifindex;
        int ret;

        lock_sock(sock->sk);
        /* various socket state tests */
        if (!(jsk->state & J1939_SOCK_BOUND)) {
                ret = -EBADFD;
                goto sendmsg_done;
        }

        priv = jsk->priv;
        ifindex = jsk->ifindex;

        if (!jsk->addr.src_name && jsk->addr.sa == J1939_NO_ADDR) {
                /* no source address assigned yet */
                ret = -EBADFD;
                goto sendmsg_done;
        }

        /* deal with provided destination address info */
        if (msg->msg_name) {
                struct sockaddr_can *addr = msg->msg_name;

                if (msg->msg_namelen < J1939_MIN_NAMELEN) {
                        ret = -EINVAL;
                        goto sendmsg_done;
                }

                if (addr->can_family != AF_CAN) {
                        ret = -EINVAL;
                        goto sendmsg_done;
                }

                if (addr->can_ifindex && addr->can_ifindex != ifindex) {
                        ret = -EBADFD;
                        goto sendmsg_done;
                }

                if (j1939_pgn_is_valid(addr->can_addr.j1939.pgn) &&
                    !j1939_pgn_is_clean_pdu(addr->can_addr.j1939.pgn)) {
                        ret = -EINVAL;
                        goto sendmsg_done;
                }

                if (!addr->can_addr.j1939.name &&
                    addr->can_addr.j1939.addr == J1939_NO_ADDR &&
                    !sock_flag(sk, SOCK_BROADCAST)) {
                        /* broadcast, but SO_BROADCAST not set */
                        ret = -EACCES;
                        goto sendmsg_done;
                }
        } else {
                if (!jsk->addr.dst_name && jsk->addr.da == J1939_NO_ADDR &&
                    !sock_flag(sk, SOCK_BROADCAST)) {
                        /* broadcast, but SO_BROADCAST not set */
                        ret = -EACCES;
                        goto sendmsg_done;
                }
        }

        ret = j1939_sk_send_loop(priv, sk, msg, size);

sendmsg_done:
        release_sock(sock->sk);

        return ret;
}

void j1939_sk_netdev_event_netdown(struct j1939_priv *priv)
{
        struct j1939_sock *jsk;
        int error_code = ENETDOWN;

        spin_lock_bh(&priv->j1939_socks_lock);
        list_for_each_entry(jsk, &priv->j1939_socks, list) {
                jsk->sk.sk_err = error_code;
                if (!sock_flag(&jsk->sk, SOCK_DEAD))
                        sk_error_report(&jsk->sk);

                j1939_sk_queue_drop_all(priv, jsk, error_code);
        }
        spin_unlock_bh(&priv->j1939_socks_lock);
}

static int j1939_sk_no_ioctlcmd(struct socket *sock, unsigned int cmd,
                                unsigned long arg)
{
        /* no ioctls for socket layer -> hand it down to NIC layer */
        return -ENOIOCTLCMD;
}

static const struct proto_ops j1939_ops = {
        .family = PF_CAN,
        .release = j1939_sk_release,
        .bind = j1939_sk_bind,
        .connect = j1939_sk_connect,
        .socketpair = sock_no_socketpair,
        .accept = sock_no_accept,
        .getname = j1939_sk_getname,
        .poll = datagram_poll,
        .ioctl = j1939_sk_no_ioctlcmd,
        .listen = sock_no_listen,
        .shutdown = sock_no_shutdown,
        .setsockopt = j1939_sk_setsockopt,
        .getsockopt = j1939_sk_getsockopt,
        .sendmsg = j1939_sk_sendmsg,
        .recvmsg = j1939_sk_recvmsg,
        .mmap = sock_no_mmap,
        .sendpage = sock_no_sendpage,
};

static struct proto j1939_proto __read_mostly = {
        .name = "CAN_J1939",
        .owner = THIS_MODULE,
        .obj_size = sizeof(struct j1939_sock),
        .init = j1939_sk_init,
};

const struct can_proto j1939_can_proto = {
        .type = SOCK_DGRAM,
        .protocol = CAN_J1939,
        .ops = &j1939_ops,
        .prot = &j1939_proto,
};