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 /* make sure we only get Classical CAN frames */
46 if (!can_is_can_skb(skb: iskb))
47 return;
48
49 /* create a copy of the skb
50 * j1939 only delivers the real data bytes,
51 * the header goes into sockaddr.
52 * j1939 may not touch the incoming skb in such way
53 */
54 skb = skb_clone(skb: iskb, GFP_ATOMIC);
55 if (!skb)
56 return;
57
58 j1939_priv_get(priv);
59 can_skb_set_owner(skb, sk: iskb->sk);
60
61 /* get a pointer to the header of the skb
62 * the skb payload (pointer) is moved, so that the next skb_data
63 * returns the actual payload
64 */
65 cf = (void *)skb->data;
66 skb_pull(skb, J1939_CAN_HDR);
67
68 /* fix length, set to dlc, with 8 maximum */
69 skb_trim(skb, min_t(uint8_t, cf->len, 8));
70
71 /* set addr */
72 skcb = j1939_skb_to_cb(skb);
73 memset(skcb, 0, sizeof(*skcb));
74
75 iskcb = j1939_skb_to_cb(skb: iskb);
76 skcb->tskey = iskcb->tskey;
77 skcb->priority = (cf->can_id >> 26) & 0x7;
78 skcb->addr.sa = cf->can_id;
79 skcb->addr.pgn = (cf->can_id >> 8) & J1939_PGN_MAX;
80 /* set default message type */
81 skcb->addr.type = J1939_TP;
82
83 if (!j1939_address_is_valid(addr: skcb->addr.sa)) {
84 netdev_err_once(priv->ndev, "%s: sa is broadcast address, ignoring!\n",
85 __func__);
86 goto done;
87 }
88
89 if (j1939_pgn_is_pdu1(pgn: skcb->addr.pgn)) {
90 /* Type 1: with destination address */
91 skcb->addr.da = skcb->addr.pgn;
92 /* normalize pgn: strip dst address */
93 skcb->addr.pgn &= 0x3ff00;
94 } else {
95 /* set broadcast address */
96 skcb->addr.da = J1939_NO_ADDR;
97 }
98
99 /* update localflags */
100 read_lock_bh(&priv->lock);
101 if (j1939_address_is_unicast(addr: skcb->addr.sa) &&
102 priv->ents[skcb->addr.sa].nusers)
103 skcb->flags |= J1939_ECU_LOCAL_SRC;
104 if (j1939_address_is_unicast(addr: skcb->addr.da) &&
105 priv->ents[skcb->addr.da].nusers)
106 skcb->flags |= J1939_ECU_LOCAL_DST;
107 read_unlock_bh(&priv->lock);
108
109 /* deliver into the j1939 stack ... */
110 j1939_ac_recv(priv, skb);
111
112 if (j1939_tp_recv(priv, skb))
113 /* this means the transport layer processed the message */
114 goto done;
115
116 j1939_simple_recv(priv, skb);
117 j1939_sk_recv(priv, skb);
118 done:
119 j1939_priv_put(priv);
120 kfree_skb(skb);
121}
122
123/* NETDEV MANAGEMENT */
124
125/* values for can_rx_(un)register */
126#define J1939_CAN_ID CAN_EFF_FLAG
127#define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)
128
129static DEFINE_MUTEX(j1939_netdev_lock);
130
131static struct j1939_priv *j1939_priv_create(struct net_device *ndev)
132{
133 struct j1939_priv *priv;
134
135 priv = kzalloc(size: sizeof(*priv), GFP_KERNEL);
136 if (!priv)
137 return NULL;
138
139 rwlock_init(&priv->lock);
140 INIT_LIST_HEAD(list: &priv->ecus);
141 priv->ndev = ndev;
142 kref_init(kref: &priv->kref);
143 kref_init(kref: &priv->rx_kref);
144 dev_hold(dev: ndev);
145
146 netdev_dbg(priv->ndev, "%s : 0x%p\n", __func__, priv);
147
148 return priv;
149}
150
151static inline void j1939_priv_set(struct net_device *ndev,
152 struct j1939_priv *priv)
153{
154 struct can_ml_priv *can_ml = can_get_ml_priv(dev: ndev);
155
156 can_ml->j1939_priv = priv;
157}
158
159static void __j1939_priv_release(struct kref *kref)
160{
161 struct j1939_priv *priv = container_of(kref, struct j1939_priv, kref);
162 struct net_device *ndev = priv->ndev;
163
164 netdev_dbg(priv->ndev, "%s: 0x%p\n", __func__, priv);
165
166 WARN_ON_ONCE(!list_empty(&priv->active_session_list));
167 WARN_ON_ONCE(!list_empty(&priv->ecus));
168 WARN_ON_ONCE(!list_empty(&priv->j1939_socks));
169
170 dev_put(dev: ndev);
171 kfree(objp: priv);
172}
173
174void j1939_priv_put(struct j1939_priv *priv)
175{
176 kref_put(kref: &priv->kref, release: __j1939_priv_release);
177}
178
179void j1939_priv_get(struct j1939_priv *priv)
180{
181 kref_get(kref: &priv->kref);
182}
183
184static int j1939_can_rx_register(struct j1939_priv *priv)
185{
186 struct net_device *ndev = priv->ndev;
187 int ret;
188
189 j1939_priv_get(priv);
190 ret = can_rx_register(net: dev_net(dev: ndev), dev: ndev, J1939_CAN_ID, J1939_CAN_MASK,
191 func: j1939_can_recv, data: priv, ident: "j1939", NULL);
192 if (ret < 0) {
193 j1939_priv_put(priv);
194 return ret;
195 }
196
197 return 0;
198}
199
200static void j1939_can_rx_unregister(struct j1939_priv *priv)
201{
202 struct net_device *ndev = priv->ndev;
203
204 can_rx_unregister(net: dev_net(dev: ndev), dev: ndev, J1939_CAN_ID, J1939_CAN_MASK,
205 func: j1939_can_recv, data: priv);
206
207 /* The last reference of priv is dropped by the RCU deferred
208 * j1939_sk_sock_destruct() of the last socket, so we can
209 * safely drop this reference here.
210 */
211 j1939_priv_put(priv);
212}
213
214static void __j1939_rx_release(struct kref *kref)
215 __releases(&j1939_netdev_lock)
216{
217 struct j1939_priv *priv = container_of(kref, struct j1939_priv,
218 rx_kref);
219
220 j1939_can_rx_unregister(priv);
221 j1939_ecu_unmap_all(priv);
222 j1939_priv_set(ndev: priv->ndev, NULL);
223 mutex_unlock(lock: &j1939_netdev_lock);
224}
225
226/* get pointer to priv without increasing ref counter */
227static inline struct j1939_priv *j1939_ndev_to_priv(struct net_device *ndev)
228{
229 struct can_ml_priv *can_ml = can_get_ml_priv(dev: ndev);
230
231 return can_ml->j1939_priv;
232}
233
234static struct j1939_priv *j1939_priv_get_by_ndev_locked(struct net_device *ndev)
235{
236 struct j1939_priv *priv;
237
238 lockdep_assert_held(&j1939_netdev_lock);
239
240 priv = j1939_ndev_to_priv(ndev);
241 if (priv)
242 j1939_priv_get(priv);
243
244 return priv;
245}
246
247static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev)
248{
249 struct j1939_priv *priv;
250
251 mutex_lock(&j1939_netdev_lock);
252 priv = j1939_priv_get_by_ndev_locked(ndev);
253 mutex_unlock(lock: &j1939_netdev_lock);
254
255 return priv;
256}
257
258struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
259{
260 struct j1939_priv *priv, *priv_new;
261 int ret;
262
263 mutex_lock(&j1939_netdev_lock);
264 priv = j1939_priv_get_by_ndev_locked(ndev);
265 if (priv) {
266 kref_get(kref: &priv->rx_kref);
267 mutex_unlock(lock: &j1939_netdev_lock);
268 return priv;
269 }
270 mutex_unlock(lock: &j1939_netdev_lock);
271
272 priv = j1939_priv_create(ndev);
273 if (!priv)
274 return ERR_PTR(error: -ENOMEM);
275
276 j1939_tp_init(priv);
277 rwlock_init(&priv->j1939_socks_lock);
278 INIT_LIST_HEAD(list: &priv->j1939_socks);
279
280 mutex_lock(&j1939_netdev_lock);
281 priv_new = j1939_priv_get_by_ndev_locked(ndev);
282 if (priv_new) {
283 /* Someone was faster than us, use their priv and roll
284 * back our's.
285 */
286 kref_get(kref: &priv_new->rx_kref);
287 mutex_unlock(lock: &j1939_netdev_lock);
288 dev_put(dev: ndev);
289 kfree(objp: priv);
290 return priv_new;
291 }
292 j1939_priv_set(ndev, priv);
293
294 ret = j1939_can_rx_register(priv);
295 if (ret < 0)
296 goto out_priv_put;
297
298 mutex_unlock(lock: &j1939_netdev_lock);
299 return priv;
300
301 out_priv_put:
302 j1939_priv_set(ndev, NULL);
303 mutex_unlock(lock: &j1939_netdev_lock);
304
305 dev_put(dev: ndev);
306 kfree(objp: priv);
307
308 return ERR_PTR(error: ret);
309}
310
311void j1939_netdev_stop(struct j1939_priv *priv)
312{
313 kref_put_mutex(kref: &priv->rx_kref, release: __j1939_rx_release, lock: &j1939_netdev_lock);
314 j1939_priv_put(priv);
315}
316
317int j1939_send_one(struct j1939_priv *priv, struct sk_buff *skb)
318{
319 int ret, dlc;
320 canid_t canid;
321 struct j1939_sk_buff_cb *skcb = j1939_skb_to_cb(skb);
322 struct can_frame *cf;
323
324 /* apply sanity checks */
325 if (j1939_pgn_is_pdu1(pgn: skcb->addr.pgn))
326 skcb->addr.pgn &= J1939_PGN_PDU1_MAX;
327 else
328 skcb->addr.pgn &= J1939_PGN_MAX;
329
330 if (skcb->priority > 7)
331 skcb->priority = 6;
332
333 ret = j1939_ac_fixup(priv, skb);
334 if (unlikely(ret))
335 goto failed;
336 dlc = skb->len;
337
338 /* re-claim the CAN_HDR from the SKB */
339 cf = skb_push(skb, J1939_CAN_HDR);
340
341 /* initialize header structure */
342 memset(cf, 0, J1939_CAN_HDR);
343
344 /* make it a full can frame again */
345 skb_put(skb, J1939_CAN_FTR + (8 - dlc));
346
347 canid = CAN_EFF_FLAG |
348 (skcb->priority << 26) |
349 (skcb->addr.pgn << 8) |
350 skcb->addr.sa;
351 if (j1939_pgn_is_pdu1(pgn: skcb->addr.pgn))
352 canid |= skcb->addr.da << 8;
353
354 cf->can_id = canid;
355 cf->len = dlc;
356
357 return can_send(skb, loop: 1);
358
359 failed:
360 kfree_skb(skb);
361 return ret;
362}
363
364static int j1939_netdev_notify(struct notifier_block *nb,
365 unsigned long msg, void *data)
366{
367 struct net_device *ndev = netdev_notifier_info_to_dev(info: data);
368 struct can_ml_priv *can_ml = can_get_ml_priv(dev: ndev);
369 struct j1939_priv *priv;
370
371 if (!can_ml)
372 goto notify_done;
373
374 priv = j1939_priv_get_by_ndev(ndev);
375 if (!priv)
376 goto notify_done;
377
378 switch (msg) {
379 case NETDEV_DOWN:
380 j1939_cancel_active_session(priv, NULL);
381 j1939_sk_netdev_event_netdown(priv);
382 j1939_ecu_unmap_all(priv);
383 break;
384 }
385
386 j1939_priv_put(priv);
387
388notify_done:
389 return NOTIFY_DONE;
390}
391
392static struct notifier_block j1939_netdev_notifier = {
393 .notifier_call = j1939_netdev_notify,
394};
395
396/* MODULE interface */
397static __init int j1939_module_init(void)
398{
399 int ret;
400
401 pr_info("can: SAE J1939\n");
402
403 ret = register_netdevice_notifier(nb: &j1939_netdev_notifier);
404 if (ret)
405 goto fail_notifier;
406
407 ret = can_proto_register(cp: &j1939_can_proto);
408 if (ret < 0) {
409 pr_err("can: registration of j1939 protocol failed\n");
410 goto fail_sk;
411 }
412
413 return 0;
414
415 fail_sk:
416 unregister_netdevice_notifier(nb: &j1939_netdev_notifier);
417 fail_notifier:
418 return ret;
419}
420
421static __exit void j1939_module_exit(void)
422{
423 can_proto_unregister(cp: &j1939_can_proto);
424
425 unregister_netdevice_notifier(nb: &j1939_netdev_notifier);
426}
427
428module_init(j1939_module_init);
429module_exit(j1939_module_exit);
430

source code of linux/net/can/j1939/main.c