xref: /openbmc/linux/net/can/af_can.c (revision f793458b)
1 // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
2 /* af_can.c - Protocol family CAN core module
3  *            (used by different CAN protocol modules)
4  *
5  * Copyright (c) 2002-2017 Volkswagen Group Electronic Research
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of Volkswagen nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * Alternatively, provided that this notice is retained in full, this
21  * software may be distributed under the terms of the GNU General
22  * Public License ("GPL") version 2, in which case the provisions of the
23  * GPL apply INSTEAD OF those given above.
24  *
25  * The provided data structures and external interfaces from this code
26  * are not restricted to be used by modules with a GPL compatible license.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
39  * DAMAGE.
40  *
41  */
42 
43 #include <linux/module.h>
44 #include <linux/stddef.h>
45 #include <linux/init.h>
46 #include <linux/kmod.h>
47 #include <linux/slab.h>
48 #include <linux/list.h>
49 #include <linux/spinlock.h>
50 #include <linux/rcupdate.h>
51 #include <linux/uaccess.h>
52 #include <linux/net.h>
53 #include <linux/netdevice.h>
54 #include <linux/socket.h>
55 #include <linux/if_ether.h>
56 #include <linux/if_arp.h>
57 #include <linux/skbuff.h>
58 #include <linux/can.h>
59 #include <linux/can/core.h>
60 #include <linux/can/skb.h>
61 #include <linux/can/can-ml.h>
62 #include <linux/ratelimit.h>
63 #include <net/net_namespace.h>
64 #include <net/sock.h>
65 
66 #include "af_can.h"
67 
68 MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
69 MODULE_LICENSE("Dual BSD/GPL");
70 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
71 	      "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
72 
73 MODULE_ALIAS_NETPROTO(PF_CAN);
74 
75 static int stats_timer __read_mostly = 1;
76 module_param(stats_timer, int, 0444);
77 MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
78 
79 static struct kmem_cache *rcv_cache __read_mostly;
80 
81 /* table of registered CAN protocols */
82 static const struct can_proto __rcu *proto_tab[CAN_NPROTO] __read_mostly;
83 static DEFINE_MUTEX(proto_tab_lock);
84 
85 static atomic_t skbcounter = ATOMIC_INIT(0);
86 
87 /* af_can socket functions */
88 
can_sock_destruct(struct sock * sk)89 void can_sock_destruct(struct sock *sk)
90 {
91 	skb_queue_purge(&sk->sk_receive_queue);
92 	skb_queue_purge(&sk->sk_error_queue);
93 }
94 EXPORT_SYMBOL(can_sock_destruct);
95 
can_get_proto(int protocol)96 static const struct can_proto *can_get_proto(int protocol)
97 {
98 	const struct can_proto *cp;
99 
100 	rcu_read_lock();
101 	cp = rcu_dereference(proto_tab[protocol]);
102 	if (cp && !try_module_get(cp->prot->owner))
103 		cp = NULL;
104 	rcu_read_unlock();
105 
106 	return cp;
107 }
108 
can_put_proto(const struct can_proto * cp)109 static inline void can_put_proto(const struct can_proto *cp)
110 {
111 	module_put(cp->prot->owner);
112 }
113 
can_create(struct net * net,struct socket * sock,int protocol,int kern)114 static int can_create(struct net *net, struct socket *sock, int protocol,
115 		      int kern)
116 {
117 	struct sock *sk;
118 	const struct can_proto *cp;
119 	int err = 0;
120 
121 	sock->state = SS_UNCONNECTED;
122 
123 	if (protocol < 0 || protocol >= CAN_NPROTO)
124 		return -EINVAL;
125 
126 	cp = can_get_proto(protocol);
127 
128 #ifdef CONFIG_MODULES
129 	if (!cp) {
130 		/* try to load protocol module if kernel is modular */
131 
132 		err = request_module("can-proto-%d", protocol);
133 
134 		/* In case of error we only print a message but don't
135 		 * return the error code immediately.  Below we will
136 		 * return -EPROTONOSUPPORT
137 		 */
138 		if (err)
139 			pr_err_ratelimited("can: request_module (can-proto-%d) failed.\n",
140 					   protocol);
141 
142 		cp = can_get_proto(protocol);
143 	}
144 #endif
145 
146 	/* check for available protocol and correct usage */
147 
148 	if (!cp)
149 		return -EPROTONOSUPPORT;
150 
151 	if (cp->type != sock->type) {
152 		err = -EPROTOTYPE;
153 		goto errout;
154 	}
155 
156 	sock->ops = cp->ops;
157 
158 	sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot, kern);
159 	if (!sk) {
160 		err = -ENOMEM;
161 		goto errout;
162 	}
163 
164 	sock_init_data(sock, sk);
165 	sk->sk_destruct = can_sock_destruct;
166 
167 	if (sk->sk_prot->init)
168 		err = sk->sk_prot->init(sk);
169 
170 	if (err) {
171 		/* release sk on errors */
172 		sock_orphan(sk);
173 		sock_put(sk);
174 	}
175 
176  errout:
177 	can_put_proto(cp);
178 	return err;
179 }
180 
181 /* af_can tx path */
182 
183 /**
184  * can_send - transmit a CAN frame (optional with local loopback)
185  * @skb: pointer to socket buffer with CAN frame in data section
186  * @loop: loopback for listeners on local CAN sockets (recommended default!)
187  *
188  * Due to the loopback this routine must not be called from hardirq context.
189  *
190  * Return:
191  *  0 on success
192  *  -ENETDOWN when the selected interface is down
193  *  -ENOBUFS on full driver queue (see net_xmit_errno())
194  *  -ENOMEM when local loopback failed at calling skb_clone()
195  *  -EPERM when trying to send on a non-CAN interface
196  *  -EMSGSIZE CAN frame size is bigger than CAN interface MTU
197  *  -EINVAL when the skb->data does not contain a valid CAN frame
198  */
can_send(struct sk_buff * skb,int loop)199 int can_send(struct sk_buff *skb, int loop)
200 {
201 	struct sk_buff *newskb = NULL;
202 	struct can_pkg_stats *pkg_stats = dev_net(skb->dev)->can.pkg_stats;
203 	int err = -EINVAL;
204 
205 	if (can_is_canxl_skb(skb)) {
206 		skb->protocol = htons(ETH_P_CANXL);
207 	} else if (can_is_can_skb(skb)) {
208 		skb->protocol = htons(ETH_P_CAN);
209 	} else if (can_is_canfd_skb(skb)) {
210 		struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
211 
212 		skb->protocol = htons(ETH_P_CANFD);
213 
214 		/* set CAN FD flag for CAN FD frames by default */
215 		cfd->flags |= CANFD_FDF;
216 	} else {
217 		goto inval_skb;
218 	}
219 
220 	/* Make sure the CAN frame can pass the selected CAN netdevice. */
221 	if (unlikely(skb->len > skb->dev->mtu)) {
222 		err = -EMSGSIZE;
223 		goto inval_skb;
224 	}
225 
226 	if (unlikely(skb->dev->type != ARPHRD_CAN)) {
227 		err = -EPERM;
228 		goto inval_skb;
229 	}
230 
231 	if (unlikely(!(skb->dev->flags & IFF_UP))) {
232 		err = -ENETDOWN;
233 		goto inval_skb;
234 	}
235 
236 	skb->ip_summed = CHECKSUM_UNNECESSARY;
237 
238 	skb_reset_mac_header(skb);
239 	skb_reset_network_header(skb);
240 	skb_reset_transport_header(skb);
241 
242 	if (loop) {
243 		/* local loopback of sent CAN frames */
244 
245 		/* indication for the CAN driver: do loopback */
246 		skb->pkt_type = PACKET_LOOPBACK;
247 
248 		/* The reference to the originating sock may be required
249 		 * by the receiving socket to check whether the frame is
250 		 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
251 		 * Therefore we have to ensure that skb->sk remains the
252 		 * reference to the originating sock by restoring skb->sk
253 		 * after each skb_clone() or skb_orphan() usage.
254 		 */
255 
256 		if (!(skb->dev->flags & IFF_ECHO)) {
257 			/* If the interface is not capable to do loopback
258 			 * itself, we do it here.
259 			 */
260 			newskb = skb_clone(skb, GFP_ATOMIC);
261 			if (!newskb) {
262 				kfree_skb(skb);
263 				return -ENOMEM;
264 			}
265 
266 			can_skb_set_owner(newskb, skb->sk);
267 			newskb->ip_summed = CHECKSUM_UNNECESSARY;
268 			newskb->pkt_type = PACKET_BROADCAST;
269 		}
270 	} else {
271 		/* indication for the CAN driver: no loopback required */
272 		skb->pkt_type = PACKET_HOST;
273 	}
274 
275 	/* send to netdevice */
276 	err = dev_queue_xmit(skb);
277 	if (err > 0)
278 		err = net_xmit_errno(err);
279 
280 	if (err) {
281 		kfree_skb(newskb);
282 		return err;
283 	}
284 
285 	if (newskb)
286 		netif_rx(newskb);
287 
288 	/* update statistics */
289 	pkg_stats->tx_frames++;
290 	pkg_stats->tx_frames_delta++;
291 
292 	return 0;
293 
294 inval_skb:
295 	kfree_skb(skb);
296 	return err;
297 }
298 EXPORT_SYMBOL(can_send);
299 
300 /* af_can rx path */
301 
can_dev_rcv_lists_find(struct net * net,struct net_device * dev)302 static struct can_dev_rcv_lists *can_dev_rcv_lists_find(struct net *net,
303 							struct net_device *dev)
304 {
305 	if (dev) {
306 		struct can_ml_priv *can_ml = can_get_ml_priv(dev);
307 		return &can_ml->dev_rcv_lists;
308 	} else {
309 		return net->can.rx_alldev_list;
310 	}
311 }
312 
313 /**
314  * effhash - hash function for 29 bit CAN identifier reduction
315  * @can_id: 29 bit CAN identifier
316  *
317  * Description:
318  *  To reduce the linear traversal in one linked list of _single_ EFF CAN
319  *  frame subscriptions the 29 bit identifier is mapped to 10 bits.
320  *  (see CAN_EFF_RCV_HASH_BITS definition)
321  *
322  * Return:
323  *  Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
324  */
effhash(canid_t can_id)325 static unsigned int effhash(canid_t can_id)
326 {
327 	unsigned int hash;
328 
329 	hash = can_id;
330 	hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
331 	hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
332 
333 	return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
334 }
335 
336 /**
337  * can_rcv_list_find - determine optimal filterlist inside device filter struct
338  * @can_id: pointer to CAN identifier of a given can_filter
339  * @mask: pointer to CAN mask of a given can_filter
340  * @dev_rcv_lists: pointer to the device filter struct
341  *
342  * Description:
343  *  Returns the optimal filterlist to reduce the filter handling in the
344  *  receive path. This function is called by service functions that need
345  *  to register or unregister a can_filter in the filter lists.
346  *
347  *  A filter matches in general, when
348  *
349  *          <received_can_id> & mask == can_id & mask
350  *
351  *  so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
352  *  relevant bits for the filter.
353  *
354  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
355  *  filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
356  *  frames there is a special filterlist and a special rx path filter handling.
357  *
358  * Return:
359  *  Pointer to optimal filterlist for the given can_id/mask pair.
360  *  Consistency checked mask.
361  *  Reduced can_id to have a preprocessed filter compare value.
362  */
can_rcv_list_find(canid_t * can_id,canid_t * mask,struct can_dev_rcv_lists * dev_rcv_lists)363 static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
364 					    struct can_dev_rcv_lists *dev_rcv_lists)
365 {
366 	canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
367 
368 	/* filter for error message frames in extra filterlist */
369 	if (*mask & CAN_ERR_FLAG) {
370 		/* clear CAN_ERR_FLAG in filter entry */
371 		*mask &= CAN_ERR_MASK;
372 		return &dev_rcv_lists->rx[RX_ERR];
373 	}
374 
375 	/* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
376 
377 #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
378 
379 	/* ensure valid values in can_mask for 'SFF only' frame filtering */
380 	if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
381 		*mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
382 
383 	/* reduce condition testing at receive time */
384 	*can_id &= *mask;
385 
386 	/* inverse can_id/can_mask filter */
387 	if (inv)
388 		return &dev_rcv_lists->rx[RX_INV];
389 
390 	/* mask == 0 => no condition testing at receive time */
391 	if (!(*mask))
392 		return &dev_rcv_lists->rx[RX_ALL];
393 
394 	/* extra filterlists for the subscription of a single non-RTR can_id */
395 	if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
396 	    !(*can_id & CAN_RTR_FLAG)) {
397 		if (*can_id & CAN_EFF_FLAG) {
398 			if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
399 				return &dev_rcv_lists->rx_eff[effhash(*can_id)];
400 		} else {
401 			if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
402 				return &dev_rcv_lists->rx_sff[*can_id];
403 		}
404 	}
405 
406 	/* default: filter via can_id/can_mask */
407 	return &dev_rcv_lists->rx[RX_FIL];
408 }
409 
410 /**
411  * can_rx_register - subscribe CAN frames from a specific interface
412  * @net: the applicable net namespace
413  * @dev: pointer to netdevice (NULL => subscribe from 'all' CAN devices list)
414  * @can_id: CAN identifier (see description)
415  * @mask: CAN mask (see description)
416  * @func: callback function on filter match
417  * @data: returned parameter for callback function
418  * @ident: string for calling module identification
419  * @sk: socket pointer (might be NULL)
420  *
421  * Description:
422  *  Invokes the callback function with the received sk_buff and the given
423  *  parameter 'data' on a matching receive filter. A filter matches, when
424  *
425  *          <received_can_id> & mask == can_id & mask
426  *
427  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
428  *  filter for error message frames (CAN_ERR_FLAG bit set in mask).
429  *
430  *  The provided pointer to the sk_buff is guaranteed to be valid as long as
431  *  the callback function is running. The callback function must *not* free
432  *  the given sk_buff while processing it's task. When the given sk_buff is
433  *  needed after the end of the callback function it must be cloned inside
434  *  the callback function with skb_clone().
435  *
436  * Return:
437  *  0 on success
438  *  -ENOMEM on missing cache mem to create subscription entry
439  *  -ENODEV unknown device
440  */
can_rx_register(struct net * net,struct net_device * dev,canid_t can_id,canid_t mask,void (* func)(struct sk_buff *,void *),void * data,char * ident,struct sock * sk)441 int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
442 		    canid_t mask, void (*func)(struct sk_buff *, void *),
443 		    void *data, char *ident, struct sock *sk)
444 {
445 	struct receiver *rcv;
446 	struct hlist_head *rcv_list;
447 	struct can_dev_rcv_lists *dev_rcv_lists;
448 	struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
449 
450 	/* insert new receiver  (dev,canid,mask) -> (func,data) */
451 
452 	if (dev && (dev->type != ARPHRD_CAN || !can_get_ml_priv(dev)))
453 		return -ENODEV;
454 
455 	if (dev && !net_eq(net, dev_net(dev)))
456 		return -ENODEV;
457 
458 	rcv = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
459 	if (!rcv)
460 		return -ENOMEM;
461 
462 	spin_lock_bh(&net->can.rcvlists_lock);
463 
464 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
465 	rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
466 
467 	rcv->can_id = can_id;
468 	rcv->mask = mask;
469 	rcv->matches = 0;
470 	rcv->func = func;
471 	rcv->data = data;
472 	rcv->ident = ident;
473 	rcv->sk = sk;
474 
475 	hlist_add_head_rcu(&rcv->list, rcv_list);
476 	dev_rcv_lists->entries++;
477 
478 	rcv_lists_stats->rcv_entries++;
479 	rcv_lists_stats->rcv_entries_max = max(rcv_lists_stats->rcv_entries_max,
480 					       rcv_lists_stats->rcv_entries);
481 	spin_unlock_bh(&net->can.rcvlists_lock);
482 
483 	return 0;
484 }
485 EXPORT_SYMBOL(can_rx_register);
486 
487 /* can_rx_delete_receiver - rcu callback for single receiver entry removal */
can_rx_delete_receiver(struct rcu_head * rp)488 static void can_rx_delete_receiver(struct rcu_head *rp)
489 {
490 	struct receiver *rcv = container_of(rp, struct receiver, rcu);
491 	struct sock *sk = rcv->sk;
492 
493 	kmem_cache_free(rcv_cache, rcv);
494 	if (sk)
495 		sock_put(sk);
496 }
497 
498 /**
499  * can_rx_unregister - unsubscribe CAN frames from a specific interface
500  * @net: the applicable net namespace
501  * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
502  * @can_id: CAN identifier
503  * @mask: CAN mask
504  * @func: callback function on filter match
505  * @data: returned parameter for callback function
506  *
507  * Description:
508  *  Removes subscription entry depending on given (subscription) values.
509  */
can_rx_unregister(struct net * net,struct net_device * dev,canid_t can_id,canid_t mask,void (* func)(struct sk_buff *,void *),void * data)510 void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
511 		       canid_t mask, void (*func)(struct sk_buff *, void *),
512 		       void *data)
513 {
514 	struct receiver *rcv = NULL;
515 	struct hlist_head *rcv_list;
516 	struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
517 	struct can_dev_rcv_lists *dev_rcv_lists;
518 
519 	if (dev && dev->type != ARPHRD_CAN)
520 		return;
521 
522 	if (dev && !net_eq(net, dev_net(dev)))
523 		return;
524 
525 	spin_lock_bh(&net->can.rcvlists_lock);
526 
527 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
528 	rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
529 
530 	/* Search the receiver list for the item to delete.  This should
531 	 * exist, since no receiver may be unregistered that hasn't
532 	 * been registered before.
533 	 */
534 	hlist_for_each_entry_rcu(rcv, rcv_list, list) {
535 		if (rcv->can_id == can_id && rcv->mask == mask &&
536 		    rcv->func == func && rcv->data == data)
537 			break;
538 	}
539 
540 	/* Check for bugs in CAN protocol implementations using af_can.c:
541 	 * 'rcv' will be NULL if no matching list item was found for removal.
542 	 * As this case may potentially happen when closing a socket while
543 	 * the notifier for removing the CAN netdev is running we just print
544 	 * a warning here.
545 	 */
546 	if (!rcv) {
547 		pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X\n",
548 			DNAME(dev), can_id, mask);
549 		goto out;
550 	}
551 
552 	hlist_del_rcu(&rcv->list);
553 	dev_rcv_lists->entries--;
554 
555 	if (rcv_lists_stats->rcv_entries > 0)
556 		rcv_lists_stats->rcv_entries--;
557 
558  out:
559 	spin_unlock_bh(&net->can.rcvlists_lock);
560 
561 	/* schedule the receiver item for deletion */
562 	if (rcv) {
563 		if (rcv->sk)
564 			sock_hold(rcv->sk);
565 		call_rcu(&rcv->rcu, can_rx_delete_receiver);
566 	}
567 }
568 EXPORT_SYMBOL(can_rx_unregister);
569 
deliver(struct sk_buff * skb,struct receiver * rcv)570 static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
571 {
572 	rcv->func(skb, rcv->data);
573 	rcv->matches++;
574 }
575 
can_rcv_filter(struct can_dev_rcv_lists * dev_rcv_lists,struct sk_buff * skb)576 static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
577 {
578 	struct receiver *rcv;
579 	int matches = 0;
580 	struct can_frame *cf = (struct can_frame *)skb->data;
581 	canid_t can_id = cf->can_id;
582 
583 	if (dev_rcv_lists->entries == 0)
584 		return 0;
585 
586 	if (can_id & CAN_ERR_FLAG) {
587 		/* check for error message frame entries only */
588 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ERR], list) {
589 			if (can_id & rcv->mask) {
590 				deliver(skb, rcv);
591 				matches++;
592 			}
593 		}
594 		return matches;
595 	}
596 
597 	/* check for unfiltered entries */
598 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ALL], list) {
599 		deliver(skb, rcv);
600 		matches++;
601 	}
602 
603 	/* check for can_id/mask entries */
604 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_FIL], list) {
605 		if ((can_id & rcv->mask) == rcv->can_id) {
606 			deliver(skb, rcv);
607 			matches++;
608 		}
609 	}
610 
611 	/* check for inverted can_id/mask entries */
612 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_INV], list) {
613 		if ((can_id & rcv->mask) != rcv->can_id) {
614 			deliver(skb, rcv);
615 			matches++;
616 		}
617 	}
618 
619 	/* check filterlists for single non-RTR can_ids */
620 	if (can_id & CAN_RTR_FLAG)
621 		return matches;
622 
623 	if (can_id & CAN_EFF_FLAG) {
624 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_eff[effhash(can_id)], list) {
625 			if (rcv->can_id == can_id) {
626 				deliver(skb, rcv);
627 				matches++;
628 			}
629 		}
630 	} else {
631 		can_id &= CAN_SFF_MASK;
632 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_sff[can_id], list) {
633 			deliver(skb, rcv);
634 			matches++;
635 		}
636 	}
637 
638 	return matches;
639 }
640 
can_receive(struct sk_buff * skb,struct net_device * dev)641 static void can_receive(struct sk_buff *skb, struct net_device *dev)
642 {
643 	struct can_dev_rcv_lists *dev_rcv_lists;
644 	struct net *net = dev_net(dev);
645 	struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
646 	int matches;
647 
648 	/* update statistics */
649 	pkg_stats->rx_frames++;
650 	pkg_stats->rx_frames_delta++;
651 
652 	/* create non-zero unique skb identifier together with *skb */
653 	while (!(can_skb_prv(skb)->skbcnt))
654 		can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
655 
656 	rcu_read_lock();
657 
658 	/* deliver the packet to sockets listening on all devices */
659 	matches = can_rcv_filter(net->can.rx_alldev_list, skb);
660 
661 	/* find receive list for this device */
662 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
663 	matches += can_rcv_filter(dev_rcv_lists, skb);
664 
665 	rcu_read_unlock();
666 
667 	/* consume the skbuff allocated by the netdevice driver */
668 	consume_skb(skb);
669 
670 	if (matches > 0) {
671 		pkg_stats->matches++;
672 		pkg_stats->matches_delta++;
673 	}
674 }
675 
can_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)676 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
677 		   struct packet_type *pt, struct net_device *orig_dev)
678 {
679 	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_can_skb(skb))) {
680 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
681 			     dev->type, skb->len);
682 
683 		kfree_skb(skb);
684 		return NET_RX_DROP;
685 	}
686 
687 	can_receive(skb, dev);
688 	return NET_RX_SUCCESS;
689 }
690 
canfd_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)691 static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
692 		     struct packet_type *pt, struct net_device *orig_dev)
693 {
694 	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) {
695 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
696 			     dev->type, skb->len);
697 
698 		kfree_skb(skb);
699 		return NET_RX_DROP;
700 	}
701 
702 	can_receive(skb, dev);
703 	return NET_RX_SUCCESS;
704 }
705 
canxl_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)706 static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
707 		     struct packet_type *pt, struct net_device *orig_dev)
708 {
709 	if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canxl_skb(skb))) {
710 		pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
711 			     dev->type, skb->len);
712 
713 		kfree_skb(skb);
714 		return NET_RX_DROP;
715 	}
716 
717 	can_receive(skb, dev);
718 	return NET_RX_SUCCESS;
719 }
720 
721 /* af_can protocol functions */
722 
723 /**
724  * can_proto_register - register CAN transport protocol
725  * @cp: pointer to CAN protocol structure
726  *
727  * Return:
728  *  0 on success
729  *  -EINVAL invalid (out of range) protocol number
730  *  -EBUSY  protocol already in use
731  *  -ENOBUF if proto_register() fails
732  */
can_proto_register(const struct can_proto * cp)733 int can_proto_register(const struct can_proto *cp)
734 {
735 	int proto = cp->protocol;
736 	int err = 0;
737 
738 	if (proto < 0 || proto >= CAN_NPROTO) {
739 		pr_err("can: protocol number %d out of range\n", proto);
740 		return -EINVAL;
741 	}
742 
743 	err = proto_register(cp->prot, 0);
744 	if (err < 0)
745 		return err;
746 
747 	mutex_lock(&proto_tab_lock);
748 
749 	if (rcu_access_pointer(proto_tab[proto])) {
750 		pr_err("can: protocol %d already registered\n", proto);
751 		err = -EBUSY;
752 	} else {
753 		RCU_INIT_POINTER(proto_tab[proto], cp);
754 	}
755 
756 	mutex_unlock(&proto_tab_lock);
757 
758 	if (err < 0)
759 		proto_unregister(cp->prot);
760 
761 	return err;
762 }
763 EXPORT_SYMBOL(can_proto_register);
764 
765 /**
766  * can_proto_unregister - unregister CAN transport protocol
767  * @cp: pointer to CAN protocol structure
768  */
can_proto_unregister(const struct can_proto * cp)769 void can_proto_unregister(const struct can_proto *cp)
770 {
771 	int proto = cp->protocol;
772 
773 	mutex_lock(&proto_tab_lock);
774 	BUG_ON(rcu_access_pointer(proto_tab[proto]) != cp);
775 	RCU_INIT_POINTER(proto_tab[proto], NULL);
776 	mutex_unlock(&proto_tab_lock);
777 
778 	synchronize_rcu();
779 
780 	proto_unregister(cp->prot);
781 }
782 EXPORT_SYMBOL(can_proto_unregister);
783 
can_pernet_init(struct net * net)784 static int can_pernet_init(struct net *net)
785 {
786 	spin_lock_init(&net->can.rcvlists_lock);
787 	net->can.rx_alldev_list =
788 		kzalloc(sizeof(*net->can.rx_alldev_list), GFP_KERNEL);
789 	if (!net->can.rx_alldev_list)
790 		goto out;
791 	net->can.pkg_stats = kzalloc(sizeof(*net->can.pkg_stats), GFP_KERNEL);
792 	if (!net->can.pkg_stats)
793 		goto out_free_rx_alldev_list;
794 	net->can.rcv_lists_stats = kzalloc(sizeof(*net->can.rcv_lists_stats), GFP_KERNEL);
795 	if (!net->can.rcv_lists_stats)
796 		goto out_free_pkg_stats;
797 
798 	if (IS_ENABLED(CONFIG_PROC_FS)) {
799 		/* the statistics are updated every second (timer triggered) */
800 		if (stats_timer) {
801 			timer_setup(&net->can.stattimer, can_stat_update,
802 				    0);
803 			mod_timer(&net->can.stattimer,
804 				  round_jiffies(jiffies + HZ));
805 		}
806 		net->can.pkg_stats->jiffies_init = jiffies;
807 		can_init_proc(net);
808 	}
809 
810 	return 0;
811 
812  out_free_pkg_stats:
813 	kfree(net->can.pkg_stats);
814  out_free_rx_alldev_list:
815 	kfree(net->can.rx_alldev_list);
816  out:
817 	return -ENOMEM;
818 }
819 
can_pernet_exit(struct net * net)820 static void can_pernet_exit(struct net *net)
821 {
822 	if (IS_ENABLED(CONFIG_PROC_FS)) {
823 		can_remove_proc(net);
824 		if (stats_timer)
825 			del_timer_sync(&net->can.stattimer);
826 	}
827 
828 	kfree(net->can.rx_alldev_list);
829 	kfree(net->can.pkg_stats);
830 	kfree(net->can.rcv_lists_stats);
831 }
832 
833 /* af_can module init/exit functions */
834 
835 static struct packet_type can_packet __read_mostly = {
836 	.type = cpu_to_be16(ETH_P_CAN),
837 	.func = can_rcv,
838 };
839 
840 static struct packet_type canfd_packet __read_mostly = {
841 	.type = cpu_to_be16(ETH_P_CANFD),
842 	.func = canfd_rcv,
843 };
844 
845 static struct packet_type canxl_packet __read_mostly = {
846 	.type = cpu_to_be16(ETH_P_CANXL),
847 	.func = canxl_rcv,
848 };
849 
850 static const struct net_proto_family can_family_ops = {
851 	.family = PF_CAN,
852 	.create = can_create,
853 	.owner  = THIS_MODULE,
854 };
855 
856 static struct pernet_operations can_pernet_ops __read_mostly = {
857 	.init = can_pernet_init,
858 	.exit = can_pernet_exit,
859 };
860 
can_init(void)861 static __init int can_init(void)
862 {
863 	int err;
864 
865 	/* check for correct padding to be able to use the structs similarly */
866 	BUILD_BUG_ON(offsetof(struct can_frame, len) !=
867 		     offsetof(struct canfd_frame, len) ||
868 		     offsetof(struct can_frame, data) !=
869 		     offsetof(struct canfd_frame, data));
870 
871 	pr_info("can: controller area network core\n");
872 
873 	rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
874 				      0, 0, NULL);
875 	if (!rcv_cache)
876 		return -ENOMEM;
877 
878 	err = register_pernet_subsys(&can_pernet_ops);
879 	if (err)
880 		goto out_pernet;
881 
882 	/* protocol register */
883 	err = sock_register(&can_family_ops);
884 	if (err)
885 		goto out_sock;
886 
887 	dev_add_pack(&can_packet);
888 	dev_add_pack(&canfd_packet);
889 	dev_add_pack(&canxl_packet);
890 
891 	return 0;
892 
893 out_sock:
894 	unregister_pernet_subsys(&can_pernet_ops);
895 out_pernet:
896 	kmem_cache_destroy(rcv_cache);
897 
898 	return err;
899 }
900 
can_exit(void)901 static __exit void can_exit(void)
902 {
903 	/* protocol unregister */
904 	dev_remove_pack(&canxl_packet);
905 	dev_remove_pack(&canfd_packet);
906 	dev_remove_pack(&can_packet);
907 	sock_unregister(PF_CAN);
908 
909 	unregister_pernet_subsys(&can_pernet_ops);
910 
911 	rcu_barrier(); /* Wait for completion of call_rcu()'s */
912 
913 	kmem_cache_destroy(rcv_cache);
914 }
915 
916 module_init(can_init);
917 module_exit(can_exit);
918