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 canfd_frame *cfd = (struct canfd_frame *)skb->data;
203 	struct can_pkg_stats *pkg_stats = dev_net(skb->dev)->can.pkg_stats;
204 	int err = -EINVAL;
205 
206 	if (skb->len == CAN_MTU) {
207 		skb->protocol = htons(ETH_P_CAN);
208 		if (unlikely(cfd->len > CAN_MAX_DLEN))
209 			goto inval_skb;
210 	} else if (skb->len == CANFD_MTU) {
211 		skb->protocol = htons(ETH_P_CANFD);
212 		if (unlikely(cfd->len > CANFD_MAX_DLEN))
213 			goto inval_skb;
214 	} else {
215 		goto inval_skb;
216 	}
217 
218 	/* Make sure the CAN frame can pass the selected CAN netdevice.
219 	 * As structs can_frame and canfd_frame are similar, we can provide
220 	 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
221 	 */
222 	if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
223 		err = -EMSGSIZE;
224 		goto inval_skb;
225 	}
226 
227 	if (unlikely(skb->dev->type != ARPHRD_CAN)) {
228 		err = -EPERM;
229 		goto inval_skb;
230 	}
231 
232 	if (unlikely(!(skb->dev->flags & IFF_UP))) {
233 		err = -ENETDOWN;
234 		goto inval_skb;
235 	}
236 
237 	skb->ip_summed = CHECKSUM_UNNECESSARY;
238 
239 	skb_reset_mac_header(skb);
240 	skb_reset_network_header(skb);
241 	skb_reset_transport_header(skb);
242 
243 	if (loop) {
244 		/* local loopback of sent CAN frames */
245 
246 		/* indication for the CAN driver: do loopback */
247 		skb->pkt_type = PACKET_LOOPBACK;
248 
249 		/* The reference to the originating sock may be required
250 		 * by the receiving socket to check whether the frame is
251 		 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
252 		 * Therefore we have to ensure that skb->sk remains the
253 		 * reference to the originating sock by restoring skb->sk
254 		 * after each skb_clone() or skb_orphan() usage.
255 		 */
256 
257 		if (!(skb->dev->flags & IFF_ECHO)) {
258 			/* If the interface is not capable to do loopback
259 			 * itself, we do it here.
260 			 */
261 			newskb = skb_clone(skb, GFP_ATOMIC);
262 			if (!newskb) {
263 				kfree_skb(skb);
264 				return -ENOMEM;
265 			}
266 
267 			can_skb_set_owner(newskb, skb->sk);
268 			newskb->ip_summed = CHECKSUM_UNNECESSARY;
269 			newskb->pkt_type = PACKET_BROADCAST;
270 		}
271 	} else {
272 		/* indication for the CAN driver: no loopback required */
273 		skb->pkt_type = PACKET_HOST;
274 	}
275 
276 	/* send to netdevice */
277 	err = dev_queue_xmit(skb);
278 	if (err > 0)
279 		err = net_xmit_errno(err);
280 
281 	if (err) {
282 		kfree_skb(newskb);
283 		return err;
284 	}
285 
286 	if (newskb)
287 		netif_rx(newskb);
288 
289 	/* update statistics */
290 	pkg_stats->tx_frames++;
291 	pkg_stats->tx_frames_delta++;
292 
293 	return 0;
294 
295 inval_skb:
296 	kfree_skb(skb);
297 	return err;
298 }
299 EXPORT_SYMBOL(can_send);
300 
301 /* af_can rx path */
302 
can_dev_rcv_lists_find(struct net * net,struct net_device * dev)303 static struct can_dev_rcv_lists *can_dev_rcv_lists_find(struct net *net,
304 							struct net_device *dev)
305 {
306 	if (dev) {
307 		struct can_ml_priv *can_ml = can_get_ml_priv(dev);
308 		return &can_ml->dev_rcv_lists;
309 	} else {
310 		return net->can.rx_alldev_list;
311 	}
312 }
313 
314 /**
315  * effhash - hash function for 29 bit CAN identifier reduction
316  * @can_id: 29 bit CAN identifier
317  *
318  * Description:
319  *  To reduce the linear traversal in one linked list of _single_ EFF CAN
320  *  frame subscriptions the 29 bit identifier is mapped to 10 bits.
321  *  (see CAN_EFF_RCV_HASH_BITS definition)
322  *
323  * Return:
324  *  Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
325  */
effhash(canid_t can_id)326 static unsigned int effhash(canid_t can_id)
327 {
328 	unsigned int hash;
329 
330 	hash = can_id;
331 	hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
332 	hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
333 
334 	return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
335 }
336 
337 /**
338  * can_rcv_list_find - determine optimal filterlist inside device filter struct
339  * @can_id: pointer to CAN identifier of a given can_filter
340  * @mask: pointer to CAN mask of a given can_filter
341  * @dev_rcv_lists: pointer to the device filter struct
342  *
343  * Description:
344  *  Returns the optimal filterlist to reduce the filter handling in the
345  *  receive path. This function is called by service functions that need
346  *  to register or unregister a can_filter in the filter lists.
347  *
348  *  A filter matches in general, when
349  *
350  *          <received_can_id> & mask == can_id & mask
351  *
352  *  so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
353  *  relevant bits for the filter.
354  *
355  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
356  *  filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
357  *  frames there is a special filterlist and a special rx path filter handling.
358  *
359  * Return:
360  *  Pointer to optimal filterlist for the given can_id/mask pair.
361  *  Consistency checked mask.
362  *  Reduced can_id to have a preprocessed filter compare value.
363  */
can_rcv_list_find(canid_t * can_id,canid_t * mask,struct can_dev_rcv_lists * dev_rcv_lists)364 static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
365 					    struct can_dev_rcv_lists *dev_rcv_lists)
366 {
367 	canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
368 
369 	/* filter for error message frames in extra filterlist */
370 	if (*mask & CAN_ERR_FLAG) {
371 		/* clear CAN_ERR_FLAG in filter entry */
372 		*mask &= CAN_ERR_MASK;
373 		return &dev_rcv_lists->rx[RX_ERR];
374 	}
375 
376 	/* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
377 
378 #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
379 
380 	/* ensure valid values in can_mask for 'SFF only' frame filtering */
381 	if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
382 		*mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
383 
384 	/* reduce condition testing at receive time */
385 	*can_id &= *mask;
386 
387 	/* inverse can_id/can_mask filter */
388 	if (inv)
389 		return &dev_rcv_lists->rx[RX_INV];
390 
391 	/* mask == 0 => no condition testing at receive time */
392 	if (!(*mask))
393 		return &dev_rcv_lists->rx[RX_ALL];
394 
395 	/* extra filterlists for the subscription of a single non-RTR can_id */
396 	if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
397 	    !(*can_id & CAN_RTR_FLAG)) {
398 		if (*can_id & CAN_EFF_FLAG) {
399 			if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
400 				return &dev_rcv_lists->rx_eff[effhash(*can_id)];
401 		} else {
402 			if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
403 				return &dev_rcv_lists->rx_sff[*can_id];
404 		}
405 	}
406 
407 	/* default: filter via can_id/can_mask */
408 	return &dev_rcv_lists->rx[RX_FIL];
409 }
410 
411 /**
412  * can_rx_register - subscribe CAN frames from a specific interface
413  * @net: the applicable net namespace
414  * @dev: pointer to netdevice (NULL => subscribe from 'all' CAN devices list)
415  * @can_id: CAN identifier (see description)
416  * @mask: CAN mask (see description)
417  * @func: callback function on filter match
418  * @data: returned parameter for callback function
419  * @ident: string for calling module identification
420  * @sk: socket pointer (might be NULL)
421  *
422  * Description:
423  *  Invokes the callback function with the received sk_buff and the given
424  *  parameter 'data' on a matching receive filter. A filter matches, when
425  *
426  *          <received_can_id> & mask == can_id & mask
427  *
428  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
429  *  filter for error message frames (CAN_ERR_FLAG bit set in mask).
430  *
431  *  The provided pointer to the sk_buff is guaranteed to be valid as long as
432  *  the callback function is running. The callback function must *not* free
433  *  the given sk_buff while processing it's task. When the given sk_buff is
434  *  needed after the end of the callback function it must be cloned inside
435  *  the callback function with skb_clone().
436  *
437  * Return:
438  *  0 on success
439  *  -ENOMEM on missing cache mem to create subscription entry
440  *  -ENODEV unknown device
441  */
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)442 int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
443 		    canid_t mask, void (*func)(struct sk_buff *, void *),
444 		    void *data, char *ident, struct sock *sk)
445 {
446 	struct receiver *rcv;
447 	struct hlist_head *rcv_list;
448 	struct can_dev_rcv_lists *dev_rcv_lists;
449 	struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
450 	int err = 0;
451 
452 	/* insert new receiver  (dev,canid,mask) -> (func,data) */
453 
454 	if (dev && dev->type != ARPHRD_CAN)
455 		return -ENODEV;
456 
457 	if (dev && !net_eq(net, dev_net(dev)))
458 		return -ENODEV;
459 
460 	rcv = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
461 	if (!rcv)
462 		return -ENOMEM;
463 
464 	spin_lock_bh(&net->can.rcvlists_lock);
465 
466 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
467 	rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
468 
469 	rcv->can_id = can_id;
470 	rcv->mask = mask;
471 	rcv->matches = 0;
472 	rcv->func = func;
473 	rcv->data = data;
474 	rcv->ident = ident;
475 	rcv->sk = sk;
476 
477 	hlist_add_head_rcu(&rcv->list, rcv_list);
478 	dev_rcv_lists->entries++;
479 
480 	rcv_lists_stats->rcv_entries++;
481 	rcv_lists_stats->rcv_entries_max = max(rcv_lists_stats->rcv_entries_max,
482 					       rcv_lists_stats->rcv_entries);
483 	spin_unlock_bh(&net->can.rcvlists_lock);
484 
485 	return err;
486 }
487 EXPORT_SYMBOL(can_rx_register);
488 
489 /* can_rx_delete_receiver - rcu callback for single receiver entry removal */
can_rx_delete_receiver(struct rcu_head * rp)490 static void can_rx_delete_receiver(struct rcu_head *rp)
491 {
492 	struct receiver *rcv = container_of(rp, struct receiver, rcu);
493 	struct sock *sk = rcv->sk;
494 
495 	kmem_cache_free(rcv_cache, rcv);
496 	if (sk)
497 		sock_put(sk);
498 }
499 
500 /**
501  * can_rx_unregister - unsubscribe CAN frames from a specific interface
502  * @net: the applicable net namespace
503  * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
504  * @can_id: CAN identifier
505  * @mask: CAN mask
506  * @func: callback function on filter match
507  * @data: returned parameter for callback function
508  *
509  * Description:
510  *  Removes subscription entry depending on given (subscription) values.
511  */
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)512 void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
513 		       canid_t mask, void (*func)(struct sk_buff *, void *),
514 		       void *data)
515 {
516 	struct receiver *rcv = NULL;
517 	struct hlist_head *rcv_list;
518 	struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
519 	struct can_dev_rcv_lists *dev_rcv_lists;
520 
521 	if (dev && dev->type != ARPHRD_CAN)
522 		return;
523 
524 	if (dev && !net_eq(net, dev_net(dev)))
525 		return;
526 
527 	spin_lock_bh(&net->can.rcvlists_lock);
528 
529 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
530 	rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
531 
532 	/* Search the receiver list for the item to delete.  This should
533 	 * exist, since no receiver may be unregistered that hasn't
534 	 * been registered before.
535 	 */
536 	hlist_for_each_entry_rcu(rcv, rcv_list, list) {
537 		if (rcv->can_id == can_id && rcv->mask == mask &&
538 		    rcv->func == func && rcv->data == data)
539 			break;
540 	}
541 
542 	/* Check for bugs in CAN protocol implementations using af_can.c:
543 	 * 'rcv' will be NULL if no matching list item was found for removal.
544 	 * As this case may potentially happen when closing a socket while
545 	 * the notifier for removing the CAN netdev is running we just print
546 	 * a warning here.
547 	 */
548 	if (!rcv) {
549 		pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X\n",
550 			DNAME(dev), can_id, mask);
551 		goto out;
552 	}
553 
554 	hlist_del_rcu(&rcv->list);
555 	dev_rcv_lists->entries--;
556 
557 	if (rcv_lists_stats->rcv_entries > 0)
558 		rcv_lists_stats->rcv_entries--;
559 
560  out:
561 	spin_unlock_bh(&net->can.rcvlists_lock);
562 
563 	/* schedule the receiver item for deletion */
564 	if (rcv) {
565 		if (rcv->sk)
566 			sock_hold(rcv->sk);
567 		call_rcu(&rcv->rcu, can_rx_delete_receiver);
568 	}
569 }
570 EXPORT_SYMBOL(can_rx_unregister);
571 
deliver(struct sk_buff * skb,struct receiver * rcv)572 static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
573 {
574 	rcv->func(skb, rcv->data);
575 	rcv->matches++;
576 }
577 
can_rcv_filter(struct can_dev_rcv_lists * dev_rcv_lists,struct sk_buff * skb)578 static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
579 {
580 	struct receiver *rcv;
581 	int matches = 0;
582 	struct can_frame *cf = (struct can_frame *)skb->data;
583 	canid_t can_id = cf->can_id;
584 
585 	if (dev_rcv_lists->entries == 0)
586 		return 0;
587 
588 	if (can_id & CAN_ERR_FLAG) {
589 		/* check for error message frame entries only */
590 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ERR], list) {
591 			if (can_id & rcv->mask) {
592 				deliver(skb, rcv);
593 				matches++;
594 			}
595 		}
596 		return matches;
597 	}
598 
599 	/* check for unfiltered entries */
600 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ALL], list) {
601 		deliver(skb, rcv);
602 		matches++;
603 	}
604 
605 	/* check for can_id/mask entries */
606 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_FIL], list) {
607 		if ((can_id & rcv->mask) == rcv->can_id) {
608 			deliver(skb, rcv);
609 			matches++;
610 		}
611 	}
612 
613 	/* check for inverted can_id/mask entries */
614 	hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_INV], list) {
615 		if ((can_id & rcv->mask) != rcv->can_id) {
616 			deliver(skb, rcv);
617 			matches++;
618 		}
619 	}
620 
621 	/* check filterlists for single non-RTR can_ids */
622 	if (can_id & CAN_RTR_FLAG)
623 		return matches;
624 
625 	if (can_id & CAN_EFF_FLAG) {
626 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_eff[effhash(can_id)], list) {
627 			if (rcv->can_id == can_id) {
628 				deliver(skb, rcv);
629 				matches++;
630 			}
631 		}
632 	} else {
633 		can_id &= CAN_SFF_MASK;
634 		hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_sff[can_id], list) {
635 			deliver(skb, rcv);
636 			matches++;
637 		}
638 	}
639 
640 	return matches;
641 }
642 
can_receive(struct sk_buff * skb,struct net_device * dev)643 static void can_receive(struct sk_buff *skb, struct net_device *dev)
644 {
645 	struct can_dev_rcv_lists *dev_rcv_lists;
646 	struct net *net = dev_net(dev);
647 	struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
648 	int matches;
649 
650 	/* update statistics */
651 	pkg_stats->rx_frames++;
652 	pkg_stats->rx_frames_delta++;
653 
654 	/* create non-zero unique skb identifier together with *skb */
655 	while (!(can_skb_prv(skb)->skbcnt))
656 		can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
657 
658 	rcu_read_lock();
659 
660 	/* deliver the packet to sockets listening on all devices */
661 	matches = can_rcv_filter(net->can.rx_alldev_list, skb);
662 
663 	/* find receive list for this device */
664 	dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
665 	matches += can_rcv_filter(dev_rcv_lists, skb);
666 
667 	rcu_read_unlock();
668 
669 	/* consume the skbuff allocated by the netdevice driver */
670 	consume_skb(skb);
671 
672 	if (matches > 0) {
673 		pkg_stats->matches++;
674 		pkg_stats->matches_delta++;
675 	}
676 }
677 
can_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)678 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
679 		   struct packet_type *pt, struct net_device *orig_dev)
680 {
681 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
682 
683 	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) {
684 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
685 			     dev->type, skb->len);
686 		goto free_skb;
687 	}
688 
689 	/* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */
690 	if (unlikely(cfd->len > CAN_MAX_DLEN)) {
691 		pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d, datalen %d\n",
692 			     dev->type, skb->len, cfd->len);
693 		goto free_skb;
694 	}
695 
696 	can_receive(skb, dev);
697 	return NET_RX_SUCCESS;
698 
699 free_skb:
700 	kfree_skb(skb);
701 	return NET_RX_DROP;
702 }
703 
canfd_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)704 static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
705 		     struct packet_type *pt, struct net_device *orig_dev)
706 {
707 	struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
708 
709 	if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) {
710 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
711 			     dev->type, skb->len);
712 		goto free_skb;
713 	}
714 
715 	/* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */
716 	if (unlikely(cfd->len > CANFD_MAX_DLEN)) {
717 		pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d, datalen %d\n",
718 			     dev->type, skb->len, cfd->len);
719 		goto free_skb;
720 	}
721 
722 	can_receive(skb, dev);
723 	return NET_RX_SUCCESS;
724 
725 free_skb:
726 	kfree_skb(skb);
727 	return NET_RX_DROP;
728 }
729 
730 /* af_can protocol functions */
731 
732 /**
733  * can_proto_register - register CAN transport protocol
734  * @cp: pointer to CAN protocol structure
735  *
736  * Return:
737  *  0 on success
738  *  -EINVAL invalid (out of range) protocol number
739  *  -EBUSY  protocol already in use
740  *  -ENOBUF if proto_register() fails
741  */
can_proto_register(const struct can_proto * cp)742 int can_proto_register(const struct can_proto *cp)
743 {
744 	int proto = cp->protocol;
745 	int err = 0;
746 
747 	if (proto < 0 || proto >= CAN_NPROTO) {
748 		pr_err("can: protocol number %d out of range\n", proto);
749 		return -EINVAL;
750 	}
751 
752 	err = proto_register(cp->prot, 0);
753 	if (err < 0)
754 		return err;
755 
756 	mutex_lock(&proto_tab_lock);
757 
758 	if (rcu_access_pointer(proto_tab[proto])) {
759 		pr_err("can: protocol %d already registered\n", proto);
760 		err = -EBUSY;
761 	} else {
762 		RCU_INIT_POINTER(proto_tab[proto], cp);
763 	}
764 
765 	mutex_unlock(&proto_tab_lock);
766 
767 	if (err < 0)
768 		proto_unregister(cp->prot);
769 
770 	return err;
771 }
772 EXPORT_SYMBOL(can_proto_register);
773 
774 /**
775  * can_proto_unregister - unregister CAN transport protocol
776  * @cp: pointer to CAN protocol structure
777  */
can_proto_unregister(const struct can_proto * cp)778 void can_proto_unregister(const struct can_proto *cp)
779 {
780 	int proto = cp->protocol;
781 
782 	mutex_lock(&proto_tab_lock);
783 	BUG_ON(rcu_access_pointer(proto_tab[proto]) != cp);
784 	RCU_INIT_POINTER(proto_tab[proto], NULL);
785 	mutex_unlock(&proto_tab_lock);
786 
787 	synchronize_rcu();
788 
789 	proto_unregister(cp->prot);
790 }
791 EXPORT_SYMBOL(can_proto_unregister);
792 
can_pernet_init(struct net * net)793 static int can_pernet_init(struct net *net)
794 {
795 	spin_lock_init(&net->can.rcvlists_lock);
796 	net->can.rx_alldev_list =
797 		kzalloc(sizeof(*net->can.rx_alldev_list), GFP_KERNEL);
798 	if (!net->can.rx_alldev_list)
799 		goto out;
800 	net->can.pkg_stats = kzalloc(sizeof(*net->can.pkg_stats), GFP_KERNEL);
801 	if (!net->can.pkg_stats)
802 		goto out_free_rx_alldev_list;
803 	net->can.rcv_lists_stats = kzalloc(sizeof(*net->can.rcv_lists_stats), GFP_KERNEL);
804 	if (!net->can.rcv_lists_stats)
805 		goto out_free_pkg_stats;
806 
807 	if (IS_ENABLED(CONFIG_PROC_FS)) {
808 		/* the statistics are updated every second (timer triggered) */
809 		if (stats_timer) {
810 			timer_setup(&net->can.stattimer, can_stat_update,
811 				    0);
812 			mod_timer(&net->can.stattimer,
813 				  round_jiffies(jiffies + HZ));
814 		}
815 		net->can.pkg_stats->jiffies_init = jiffies;
816 		can_init_proc(net);
817 	}
818 
819 	return 0;
820 
821  out_free_pkg_stats:
822 	kfree(net->can.pkg_stats);
823  out_free_rx_alldev_list:
824 	kfree(net->can.rx_alldev_list);
825  out:
826 	return -ENOMEM;
827 }
828 
can_pernet_exit(struct net * net)829 static void can_pernet_exit(struct net *net)
830 {
831 	if (IS_ENABLED(CONFIG_PROC_FS)) {
832 		can_remove_proc(net);
833 		if (stats_timer)
834 			del_timer_sync(&net->can.stattimer);
835 	}
836 
837 	kfree(net->can.rx_alldev_list);
838 	kfree(net->can.pkg_stats);
839 	kfree(net->can.rcv_lists_stats);
840 }
841 
842 /* af_can module init/exit functions */
843 
844 static struct packet_type can_packet __read_mostly = {
845 	.type = cpu_to_be16(ETH_P_CAN),
846 	.func = can_rcv,
847 };
848 
849 static struct packet_type canfd_packet __read_mostly = {
850 	.type = cpu_to_be16(ETH_P_CANFD),
851 	.func = canfd_rcv,
852 };
853 
854 static const struct net_proto_family can_family_ops = {
855 	.family = PF_CAN,
856 	.create = can_create,
857 	.owner  = THIS_MODULE,
858 };
859 
860 static struct pernet_operations can_pernet_ops __read_mostly = {
861 	.init = can_pernet_init,
862 	.exit = can_pernet_exit,
863 };
864 
can_init(void)865 static __init int can_init(void)
866 {
867 	int err;
868 
869 	/* check for correct padding to be able to use the structs similarly */
870 	BUILD_BUG_ON(offsetof(struct can_frame, len) !=
871 		     offsetof(struct canfd_frame, len) ||
872 		     offsetof(struct can_frame, data) !=
873 		     offsetof(struct canfd_frame, data));
874 
875 	pr_info("can: controller area network core\n");
876 
877 	rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
878 				      0, 0, NULL);
879 	if (!rcv_cache)
880 		return -ENOMEM;
881 
882 	err = register_pernet_subsys(&can_pernet_ops);
883 	if (err)
884 		goto out_pernet;
885 
886 	/* protocol register */
887 	err = sock_register(&can_family_ops);
888 	if (err)
889 		goto out_sock;
890 
891 	dev_add_pack(&can_packet);
892 	dev_add_pack(&canfd_packet);
893 
894 	return 0;
895 
896 out_sock:
897 	unregister_pernet_subsys(&can_pernet_ops);
898 out_pernet:
899 	kmem_cache_destroy(rcv_cache);
900 
901 	return err;
902 }
903 
can_exit(void)904 static __exit void can_exit(void)
905 {
906 	/* protocol unregister */
907 	dev_remove_pack(&canfd_packet);
908 	dev_remove_pack(&can_packet);
909 	sock_unregister(PF_CAN);
910 
911 	unregister_pernet_subsys(&can_pernet_ops);
912 
913 	rcu_barrier(); /* Wait for completion of call_rcu()'s */
914 
915 	kmem_cache_destroy(rcv_cache);
916 }
917 
918 module_init(can_init);
919 module_exit(can_exit);
920