xref: /openbmc/linux/net/can/j1939/main.c (revision ab2a6839)
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 
23 MODULE_DESCRIPTION("PF_CAN SAE J1939");
24 MODULE_LICENSE("GPL v2");
25 MODULE_AUTHOR("EIA Electronics (Kurt Van Dijck & Pieter Beyens)");
26 MODULE_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 /* lowest layer */
j1939_can_recv(struct sk_buff * iskb,void * data)34 static void j1939_can_recv(struct sk_buff *iskb, void *data)
35 {
36 	struct j1939_priv *priv = data;
37 	struct sk_buff *skb;
38 	struct j1939_sk_buff_cb *skcb, *iskcb;
39 	struct can_frame *cf;
40 
41 	/* make sure we only get Classical CAN frames */
42 	if (!can_is_can_skb(iskb))
43 		return;
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->len, 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 
125 static DEFINE_MUTEX(j1939_netdev_lock);
126 
j1939_priv_create(struct net_device * ndev)127 static 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 
j1939_priv_set(struct net_device * ndev,struct j1939_priv * priv)147 static 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 
__j1939_priv_release(struct kref * kref)155 static 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 
j1939_priv_put(struct j1939_priv * priv)170 void j1939_priv_put(struct j1939_priv *priv)
171 {
172 	kref_put(&priv->kref, __j1939_priv_release);
173 }
174 
j1939_priv_get(struct j1939_priv * priv)175 void j1939_priv_get(struct j1939_priv *priv)
176 {
177 	kref_get(&priv->kref);
178 }
179 
j1939_can_rx_register(struct j1939_priv * priv)180 static 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 
j1939_can_rx_unregister(struct j1939_priv * priv)196 static 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 
__j1939_rx_release(struct kref * kref)210 static 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 */
j1939_ndev_to_priv(struct net_device * ndev)223 static 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 
j1939_priv_get_by_ndev_locked(struct net_device * ndev)230 static 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 
j1939_priv_get_by_ndev(struct net_device * ndev)243 static 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 
j1939_netdev_start(struct net_device * ndev)254 struct 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 	rwlock_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 
j1939_netdev_stop(struct j1939_priv * priv)307 void 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 
j1939_send_one(struct j1939_priv * priv,struct sk_buff * skb)313 int 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_zero(skb, 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->len = dlc;
352 
353 	return can_send(skb, 1);
354 
355  failed:
356 	kfree_skb(skb);
357 	return ret;
358 }
359 
j1939_netdev_notify(struct notifier_block * nb,unsigned long msg,void * data)360 static 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 
384 notify_done:
385 	return NOTIFY_DONE;
386 }
387 
388 static struct notifier_block j1939_netdev_notifier = {
389 	.notifier_call = j1939_netdev_notify,
390 };
391 
392 /* MODULE interface */
j1939_module_init(void)393 static __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 
j1939_module_exit(void)417 static __exit void j1939_module_exit(void)
418 {
419 	can_proto_unregister(&j1939_can_proto);
420 
421 	unregister_netdevice_notifier(&j1939_netdev_notifier);
422 }
423 
424 module_init(j1939_module_init);
425 module_exit(j1939_module_exit);
426