xref: /kernel/linux/linux-5.10/net/can/j1939/main.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0
2// Copyright (c) 2010-2011 EIA Electronics,
3//                         Pieter Beyens <pieter.beyens@eia.be>
4// Copyright (c) 2010-2011 EIA Electronics,
5//                         Kurt Van Dijck <kurt.van.dijck@eia.be>
6// Copyright (c) 2018 Protonic,
7//                         Robin van der Gracht <robin@protonic.nl>
8// Copyright (c) 2017-2019 Pengutronix,
9//                         Marc Kleine-Budde <kernel@pengutronix.de>
10// Copyright (c) 2017-2019 Pengutronix,
11//                         Oleksij Rempel <kernel@pengutronix.de>
12
13/* Core of can-j1939 that links j1939 to CAN. */
14
15#include <linux/can/can-ml.h>
16#include <linux/can/core.h>
17#include <linux/can/skb.h>
18#include <linux/if_arp.h>
19#include <linux/module.h>
20
21#include "j1939-priv.h"
22
23MODULE_DESCRIPTION("PF_CAN SAE J1939");
24MODULE_LICENSE("GPL v2");
25MODULE_AUTHOR("EIA Electronics (Kurt Van Dijck & Pieter Beyens)");
26MODULE_ALIAS("can-proto-" __stringify(CAN_J1939));
27
28/* LOWLEVEL CAN interface */
29
30/* CAN_HDR: #bytes before can_frame data part */
31#define J1939_CAN_HDR (offsetof(struct can_frame, data))
32
33/* CAN_FTR: #bytes beyond data part */
34#define J1939_CAN_FTR (sizeof(struct can_frame) - J1939_CAN_HDR - \
35		 sizeof(((struct can_frame *)0)->data))
36
37/* lowest layer */
38static void j1939_can_recv(struct sk_buff *iskb, void *data)
39{
40	struct j1939_priv *priv = data;
41	struct sk_buff *skb;
42	struct j1939_sk_buff_cb *skcb, *iskcb;
43	struct can_frame *cf;
44
45	/* create a copy of the skb
46	 * j1939 only delivers the real data bytes,
47	 * the header goes into sockaddr.
48	 * j1939 may not touch the incoming skb in such way
49	 */
50	skb = skb_clone(iskb, GFP_ATOMIC);
51	if (!skb)
52		return;
53
54	j1939_priv_get(priv);
55	can_skb_set_owner(skb, iskb->sk);
56
57	/* get a pointer to the header of the skb
58	 * the skb payload (pointer) is moved, so that the next skb_data
59	 * returns the actual payload
60	 */
61	cf = (void *)skb->data;
62	skb_pull(skb, J1939_CAN_HDR);
63
64	/* fix length, set to dlc, with 8 maximum */
65	skb_trim(skb, min_t(uint8_t, cf->can_dlc, 8));
66
67	/* set addr */
68	skcb = j1939_skb_to_cb(skb);
69	memset(skcb, 0, sizeof(*skcb));
70
71	iskcb = j1939_skb_to_cb(iskb);
72	skcb->tskey = iskcb->tskey;
73	skcb->priority = (cf->can_id >> 26) & 0x7;
74	skcb->addr.sa = cf->can_id;
75	skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
76	/* set default message type */
77	skcb->addr.type = J1939_TP;
78
79	if (!j1939_address_is_valid(skcb->addr.sa)) {
80		netdev_err_once(priv->ndev, "%s: sa is broadcast address, ignoring!\n",
81				__func__);
82		goto done;
83	}
84
85	if (j1939_pgn_is_pdu1(skcb->addr.pgn)) {
86		/* Type 1: with destination address */
87		skcb->addr.da = skcb->addr.pgn;
88		/* normalize pgn: strip dst address */
89		skcb->addr.pgn &= 0x3ff00;
90	} else {
91		/* set broadcast address */
92		skcb->addr.da = J1939_NO_ADDR;
93	}
94
95	/* update localflags */
96	read_lock_bh(&priv->lock);
97	if (j1939_address_is_unicast(skcb->addr.sa) &&
98	    priv->ents[skcb->addr.sa].nusers)
99		skcb->flags |= J1939_ECU_LOCAL_SRC;
100	if (j1939_address_is_unicast(skcb->addr.da) &&
101	    priv->ents[skcb->addr.da].nusers)
102		skcb->flags |= J1939_ECU_LOCAL_DST;
103	read_unlock_bh(&priv->lock);
104
105	/* deliver into the j1939 stack ... */
106	j1939_ac_recv(priv, skb);
107
108	if (j1939_tp_recv(priv, skb))
109		/* this means the transport layer processed the message */
110		goto done;
111
112	j1939_simple_recv(priv, skb);
113	j1939_sk_recv(priv, skb);
114 done:
115	j1939_priv_put(priv);
116	kfree_skb(skb);
117}
118
119/* NETDEV MANAGEMENT */
120
121/* values for can_rx_(un)register */
122#define J1939_CAN_ID CAN_EFF_FLAG
123#define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)
124
125static DEFINE_MUTEX(j1939_netdev_lock);
126
127static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
128{
129	struct j1939_priv *priv;
130
131	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
132	if (!priv)
133		return NULL;
134
135	rwlock_init(&priv->lock);
136	INIT_LIST_HEAD(&priv->ecus);
137	priv->ndev = ndev;
138	kref_init(&priv->kref);
139	kref_init(&priv->rx_kref);
140	dev_hold(ndev);
141
142	netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
143
144	return priv;
145}
146
147static inline void j1939_priv_set(struct net_device *ndev,
148				  struct j1939_priv *priv)
149{
150	struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
151
152	can_ml->j1939_priv = priv;
153}
154
155static void __j1939_priv_release(struct kref *kref)
156{
157	struct j1939_priv *priv = container_of(kref, struct j1939_priv, kref);
158	struct net_device *ndev = priv->ndev;
159
160	netdev_dbg(priv->ndev, "%s: 0x%p\n", __func__, priv);
161
162	WARN_ON_ONCE(!list_empty(&priv->active_session_list));
163	WARN_ON_ONCE(!list_empty(&priv->ecus));
164	WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
165
166	dev_put(ndev);
167	kfree(priv);
168}
169
170void j1939_priv_put(struct j1939_priv *priv)
171{
172	kref_put(&priv->kref, __j1939_priv_release);
173}
174
175void j1939_priv_get(struct j1939_priv *priv)
176{
177	kref_get(&priv->kref);
178}
179
180static int j1939_can_rx_register(struct j1939_priv *priv)
181{
182	struct net_device *ndev = priv->ndev;
183	int ret;
184
185	j1939_priv_get(priv);
186	ret = can_rx_register(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
187			      j1939_can_recv, priv, "j1939", NULL);
188	if (ret < 0) {
189		j1939_priv_put(priv);
190		return ret;
191	}
192
193	return 0;
194}
195
196static void j1939_can_rx_unregister(struct j1939_priv *priv)
197{
198	struct net_device *ndev = priv->ndev;
199
200	can_rx_unregister(dev_net(ndev), ndev, J1939_CAN_ID, J1939_CAN_MASK,
201			  j1939_can_recv, priv);
202
203	/* The last reference of priv is dropped by the RCU deferred
204	 * j1939_sk_sock_destruct() of the last socket, so we can
205	 * safely drop this reference here.
206	 */
207	j1939_priv_put(priv);
208}
209
210static void __j1939_rx_release(struct kref *kref)
211	__releases(&j1939_netdev_lock)
212{
213	struct j1939_priv *priv = container_of(kref, struct j1939_priv,
214					       rx_kref);
215
216	j1939_can_rx_unregister(priv);
217	j1939_ecu_unmap_all(priv);
218	j1939_priv_set(priv->ndev, NULL);
219	mutex_unlock(&j1939_netdev_lock);
220}
221
222/* get pointer to priv without increasing ref counter */
223static inline struct j1939_priv *j1939_ndev_to_priv(struct net_device *ndev)
224{
225	struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
226
227	return can_ml->j1939_priv;
228}
229
230static struct j1939_priv *j1939_priv_get_by_ndev_locked(struct net_device *ndev)
231{
232	struct j1939_priv *priv;
233
234	lockdep_assert_held(&j1939_netdev_lock);
235
236	priv = j1939_ndev_to_priv(ndev);
237	if (priv)
238		j1939_priv_get(priv);
239
240	return priv;
241}
242
243static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev)
244{
245	struct j1939_priv *priv;
246
247	mutex_lock(&j1939_netdev_lock);
248	priv = j1939_priv_get_by_ndev_locked(ndev);
249	mutex_unlock(&j1939_netdev_lock);
250
251	return priv;
252}
253
254struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
255{
256	struct j1939_priv *priv, *priv_new;
257	int ret;
258
259	mutex_lock(&j1939_netdev_lock);
260	priv = j1939_priv_get_by_ndev_locked(ndev);
261	if (priv) {
262		kref_get(&priv->rx_kref);
263		mutex_unlock(&j1939_netdev_lock);
264		return priv;
265	}
266	mutex_unlock(&j1939_netdev_lock);
267
268	priv = j1939_priv_create(ndev);
269	if (!priv)
270		return ERR_PTR(-ENOMEM);
271
272	j1939_tp_init(priv);
273	spin_lock_init(&priv->j1939_socks_lock);
274	INIT_LIST_HEAD(&priv->j1939_socks);
275
276	mutex_lock(&j1939_netdev_lock);
277	priv_new = j1939_priv_get_by_ndev_locked(ndev);
278	if (priv_new) {
279		/* Someone was faster than us, use their priv and roll
280		 * back our's.
281		 */
282		kref_get(&priv_new->rx_kref);
283		mutex_unlock(&j1939_netdev_lock);
284		dev_put(ndev);
285		kfree(priv);
286		return priv_new;
287	}
288	j1939_priv_set(ndev, priv);
289
290	ret = j1939_can_rx_register(priv);
291	if (ret < 0)
292		goto out_priv_put;
293
294	mutex_unlock(&j1939_netdev_lock);
295	return priv;
296
297 out_priv_put:
298	j1939_priv_set(ndev, NULL);
299	mutex_unlock(&j1939_netdev_lock);
300
301	dev_put(ndev);
302	kfree(priv);
303
304	return ERR_PTR(ret);
305}
306
307void j1939_netdev_stop(struct j1939_priv *priv)
308{
309	kref_put_mutex(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock);
310	j1939_priv_put(priv);
311}
312
313int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
314{
315	int ret, dlc;
316	canid_t canid;
317	struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
318	struct can_frame *cf;
319
320	/* apply sanity checks */
321	if (j1939_pgn_is_pdu1(skcb->addr.pgn))
322		skcb->addr.pgn &= J1939_PGN_PDU1_MAX;
323	else
324		skcb->addr.pgn &= J1939_PGN_MAX;
325
326	if (skcb->priority > 7)
327		skcb->priority = 6;
328
329	ret = j1939_ac_fixup(priv, skb);
330	if (unlikely(ret))
331		goto failed;
332	dlc = skb->len;
333
334	/* re-claim the CAN_HDR from the SKB */
335	cf = skb_push(skb, J1939_CAN_HDR);
336
337	/* initialize header structure */
338	memset(cf, 0, J1939_CAN_HDR);
339
340	/* make it a full can frame again */
341	skb_put(skb, J1939_CAN_FTR + (8 - dlc));
342
343	canid = CAN_EFF_FLAG |
344		(skcb->priority << 26) |
345		(skcb->addr.pgn << 8) |
346		skcb->addr.sa;
347	if (j1939_pgn_is_pdu1(skcb->addr.pgn))
348		canid |= skcb->addr.da << 8;
349
350	cf->can_id = canid;
351	cf->can_dlc = dlc;
352
353	return can_send(skb, 1);
354
355 failed:
356	kfree_skb(skb);
357	return ret;
358}
359
360static int j1939_netdev_notify(struct notifier_block *nb,
361			       unsigned long msg, void *data)
362{
363	struct net_device *ndev = netdev_notifier_info_to_dev(data);
364	struct can_ml_priv *can_ml = can_get_ml_priv(ndev);
365	struct j1939_priv *priv;
366
367	if (!can_ml)
368		goto notify_done;
369
370	priv = j1939_priv_get_by_ndev(ndev);
371	if (!priv)
372		goto notify_done;
373
374	switch (msg) {
375	case NETDEV_DOWN:
376		j1939_cancel_active_session(priv, NULL);
377		j1939_sk_netdev_event_netdown(priv);
378		j1939_ecu_unmap_all(priv);
379		break;
380	}
381
382	j1939_priv_put(priv);
383
384notify_done:
385	return NOTIFY_DONE;
386}
387
388static struct notifier_block j1939_netdev_notifier = {
389	.notifier_call = j1939_netdev_notify,
390};
391
392/* MODULE interface */
393static __init int j1939_module_init(void)
394{
395	int ret;
396
397	pr_info("can: SAE J1939\n");
398
399	ret = register_netdevice_notifier(&j1939_netdev_notifier);
400	if (ret)
401		goto fail_notifier;
402
403	ret = can_proto_register(&j1939_can_proto);
404	if (ret < 0) {
405		pr_err("can: registration of j1939 protocol failed\n");
406		goto fail_sk;
407	}
408
409	return 0;
410
411 fail_sk:
412	unregister_netdevice_notifier(&j1939_netdev_notifier);
413 fail_notifier:
414	return ret;
415}
416
417static __exit void j1939_module_exit(void)
418{
419	can_proto_unregister(&j1939_can_proto);
420
421	unregister_netdevice_notifier(&j1939_netdev_notifier);
422}
423
424module_init(j1939_module_init);
425module_exit(j1939_module_exit);
426