// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2010-2011 EIA Electronics,
// Pieter Beyens <[email protected]>
// Copyright (c) 2010-2011 EIA Electronics,
// Kurt Van Dijck <[email protected]>
// Copyright (c) 2018 Protonic,
// Robin van der Gracht <[email protected]>
// Copyright (c) 2017-2019 Pengutronix,
// Marc Kleine-Budde <[email protected]>
// Copyright (c) 2017-2019 Pengutronix,
// Oleksij Rempel <[email protected]>
/* Core of can-j1939 that links j1939 to CAN. */
#include <linux/can/can-ml.h>
#include <linux/can/core.h>
#include <linux/can/skb.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include "j1939-priv.h"
MODULE_DESCRIPTION("PF_CAN SAE J1939");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("EIA Electronics (Kurt Van Dijck & Pieter Beyens)");
MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
/* LOWLEVEL CAN interface */
/* CAN_HDR: #bytes before can_frame data part */
#define J1939_CAN_HDR (offsetof(struct can_frame, data))
/* lowest layer */
static void j1939_can_recv(struct sk_buff *iskb, void *data)
{
struct j1939_priv *priv = data;
struct sk_buff *skb;
struct j1939_sk_buff_cb *skcb, *iskcb;
struct can_frame *cf;
/* make sure we only get Classical CAN frames */
if (!can_is_can_skb(iskb))
return;
/* create a copy of the skb
* j1939 only delivers the real data bytes,
* the header goes into sockaddr.
* j1939 may not touch the incoming skb in such way
*/
skb = skb_clone(iskb, GFP_ATOMIC);
if (!skb)
return;
j1939_priv_get(priv);
can_skb_set_owner(skb, iskb->sk);
/* get a pointer to the header of the skb
* the skb payload (pointer) is moved, so that the next skb_data
* returns the actual payload
*/
cf = (void *)skb->data;
skb_pull(skb, J1939_CAN_HDR);
/* fix length, set to dlc, with 8 maximum */
skb_trim(skb, min_t(uint8_t, cf->len, 8));
/* set addr */
skcb = j1939_skb_to_cb(skb);
memset(skcb, 0, sizeof(*skcb));
iskcb = j1939_skb_to_cb(iskb);
skcb->tskey = iskcb->tskey;
skcb->priority = (cf->can_id >> 26) & 0x7;
skcb->addr.sa = cf->can_id;
skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
/* set default message type */
skcb->addr.type = J1939_TP;
if (!j1939_address_is_valid(skcb->addr.sa)) {
netdev_err_once(priv->ndev, "%s: sa is broadcast address, ignoring!\n",
__func__);
goto done;
}
if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
/* Type 1: with destination address */
skcb->addr.da = skcb->addr.pgn;
/* normalize pgn: strip dst address */
skcb->addr.pgn &= 0x3ff00;
} else {
/* set broadcast address */
skcb->addr.da = J1939_NO_ADDR;
}
/* update localflags */
read_lock_bh(&priv->lock);
if (j1939_address_is_unicast(skcb->addr.sa) &&
priv->ents[skcb->addr.sa].nusers)
skcb->flags |= J1939_ECU_LOCAL_SRC;
if (j1939_address_is_unicast(skcb->addr.da) &&
priv->ents[skcb->addr.da].nusers)
skcb->flags |= J1939_ECU_LOCAL_DST;
read_unlock_bh(&priv->lock);
/* deliver into the j1939 stack ... */
j1939_ac_recv(priv, skb);
if (j1939_tp_recv(priv, skb))
/* this means the transport layer processed the message */
goto done;
j1939_simple_recv(priv, skb);
j1939_sk_recv(priv, skb);
done:
j1939_priv_put(priv);
kfree_skb(skb);
}
/* NETDEV MANAGEMENT */
/* values for can_rx_(un)register */
#define J1939_CAN_ID CAN_EFF_FLAG
#define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)
static DEFINE_MUTEX(j1939_netdev_lock);
static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
{
struct j1939_priv *priv;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return NULL;
rwlock_init(&priv->lock);
INIT_LIST_HEAD(&priv->ecus);
priv->ndev = ndev;
kref_init(&priv->kref);
kref_init(&priv->rx_kref);
dev_hold(ndev);
netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
return priv;
}
static inline void j1939_priv_set(struct net_device *ndev,
struct j1939_priv *priv)
{
struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
can_ml->j1939_priv = priv;
}
static void __j1939_priv_release(struct kref *kref)
{
struct j1939_priv *priv = container_of(kref, struct j1939_priv, kref);
struct net_device *ndev = priv->ndev;
netdev_dbg(priv->ndev, "%s: 0x%p\n", __func__, priv);
WARN_ON_ONCE(!list_empty(&priv->active_session_list));
WARN_ON_ONCE(!list_empty(&priv->ecus));
WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
dev_put(ndev);
kfree(priv);
}
void j1939_priv_put(struct j1939_priv *priv)
{
kref_put(&priv->kref, __j1939_priv_release);
}
void j1939_priv_get(struct j1939_priv *priv)
{
kref_get(&priv->kref);
}
static int j1939_can_rx_register(struct j1939_priv *priv)
{
struct net_device *ndev = priv->ndev;
int ret;
j1939_priv_get(priv);
ret = can_rx_register(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
j1939_can_recv, priv, "j1939", NULL);
if (ret < 0) {
j1939_priv_put(priv);
return ret;
}
return 0;
}
static void j1939_can_rx_unregister(struct j1939_priv *priv)
{
struct net_device *ndev = priv->ndev;
can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
j1939_can_recv, priv);
/* The last reference of priv is dropped by the RCU deferred
* j1939_sk_sock_destruct() of the last socket, so we can
* safely drop this reference here.
*/
j1939_priv_put(priv);
}
static void __j1939_rx_release(struct kref *kref)
__releases(&j1939_netdev_lock)
{
struct j1939_priv *priv = container_of(kref, struct j1939_priv,
rx_kref);
j1939_can_rx_unregister(priv);
j1939_ecu_unmap_all(priv);
j1939_priv_set(priv->ndev, NULL);
mutex_unlock(&j1939_netdev_lock);
}
/* get pointer to priv without increasing ref counter */
static inline struct j1939_priv *j1939_ndev_to_priv(struct net_device *ndev)
{
struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
return can_ml->j1939_priv;
}
static struct j1939_priv *j1939_priv_get_by_ndev_locked(struct net_device *ndev)
{
struct j1939_priv *priv;
lockdep_assert_held(&j1939_netdev_lock);
priv = j1939_ndev_to_priv(ndev);
if (priv)
j1939_priv_get(priv);
return priv;
}
static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev)
{
struct j1939_priv *priv;
mutex_lock(&j1939_netdev_lock);
priv = j1939_priv_get_by_ndev_locked(ndev);
mutex_unlock(&j1939_netdev_lock);
return priv;
}
struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
{
struct j1939_priv *priv, *priv_new;
int ret;
mutex_lock(&j1939_netdev_lock);
priv = j1939_priv_get_by_ndev_locked(ndev);
if (priv) {
kref_get(&priv->rx_kref);
mutex_unlock(&j1939_netdev_lock);
return priv;
}
mutex_unlock(&j1939_netdev_lock);
priv = j1939_priv_create(ndev);
if (!priv)
return ERR_PTR(-ENOMEM);
j1939_tp_init(priv);
rwlock_init(&priv->j1939_socks_lock);
INIT_LIST_HEAD(&priv->j1939_socks);
mutex_lock(&j1939_netdev_lock);
priv_new = j1939_priv_get_by_ndev_locked(ndev);
if (priv_new) {
/* Someone was faster than us, use their priv and roll
* back our's.
*/
kref_get(&priv_new->rx_kref);
mutex_unlock(&j1939_netdev_lock);
dev_put(ndev);
kfree(priv);
return priv_new;
}
j1939_priv_set(ndev, priv);
ret = j1939_can_rx_register(priv);
if (ret < 0)
goto out_priv_put;
mutex_unlock(&j1939_netdev_lock);
return priv;
out_priv_put:
j1939_priv_set(ndev, NULL);
mutex_unlock(&j1939_netdev_lock);
dev_put(ndev);
kfree(priv);
return ERR_PTR(ret);
}
void j1939_netdev_stop(struct j1939_priv *priv)
{
kref_put_mutex(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock);
j1939_priv_put(priv);
}
int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
{
int ret, dlc;
canid_t canid;
struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
struct can_frame *cf;
/* apply sanity checks */
if (j1939_pgn_is_pdu1(skcb->addr.pgn))
skcb->addr.pgn &= J1939_PGN_PDU1_MAX;
else
skcb->addr.pgn &= J1939_PGN_MAX;
if (skcb->priority > 7)
skcb->priority = 6;
ret = j1939_ac_fixup(priv, skb);
if (unlikely(ret))
goto failed;
dlc = skb->len;
/* re-claim the CAN_HDR from the SKB */
cf = skb_push(skb, J1939_CAN_HDR);
/* initialize header structure */
memset(cf, 0, J1939_CAN_HDR);
/* make it a full can frame again */
skb_put_zero(skb, 8 - dlc);
canid = CAN_EFF_FLAG |
(skcb->priority << 26) |
(skcb->addr.pgn << 8) |
skcb->addr.sa;
if (j1939_pgn_is_pdu1(skcb->addr.pgn))
canid |= skcb->addr.da << 8;
cf->can_id = canid;
cf->len = dlc;
return can_send(skb, 1);
failed:
kfree_skb(skb);
return ret;
}
static int j1939_netdev_notify(struct notifier_block *nb,
unsigned long msg, void *data)
{
struct net_device *ndev = netdev_notifier_info_to_dev(data);
struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
struct j1939_priv *priv;
if (!can_ml)
goto notify_done;
priv = j1939_priv_get_by_ndev(ndev);
if (!priv)
goto notify_done;
switch (msg) {
case NETDEV_DOWN:
j1939_cancel_active_session(priv, NULL);
j1939_sk_netdev_event_netdown(priv);
j1939_ecu_unmap_all(priv);
break;
}
j1939_priv_put(priv);
notify_done:
return NOTIFY_DONE;
}
static struct notifier_block j1939_netdev_notifier = {
.notifier_call = j1939_netdev_notify,
};
/* MODULE interface */
static __init int j1939_module_init(void)
{
int ret;
pr_info("can: SAE J1939\n");
ret = register_netdevice_notifier(&j1939_netdev_notifier);
if (ret)
goto fail_notifier;
ret = can_proto_register(&j1939_can_proto);
if (ret < 0) {
pr_err("can: registration of j1939 protocol failed\n");
goto fail_sk;
}
return 0;
fail_sk:
unregister_netdevice_notifier(&j1939_netdev_notifier);
fail_notifier:
return ret;
}
static __exit void j1939_module_exit(void)
{
can_proto_unregister(&j1939_can_proto);
unregister_netdevice_notifier(&j1939_netdev_notifier);
}
module_init(j1939_module_init);
module_exit(j1939_module_exit);
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