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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
68MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
69MODULE_LICENSE("Dual BSD/GPL");
70MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
71 "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
72
73MODULE_ALIAS_NETPROTO(PF_CAN);
74
75static int stats_timer __read_mostly = 1;
76module_param(stats_timer, int, 0444);
77MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
78
79static struct kmem_cache *rcv_cache __read_mostly;
80
81/* table of registered CAN protocols */
82static const struct can_proto __rcu *proto_tab[CAN_NPROTO] __read_mostly;
83static DEFINE_MUTEX(proto_tab_lock);
84
85static atomic_t skbcounter = ATOMIC_INIT(0);
86
87/* af_can socket functions */
88
89void can_sock_destruct(struct sock *sk)
90{
91 skb_queue_purge(&sk->sk_receive_queue);
92 skb_queue_purge(&sk->sk_error_queue);
93}
94EXPORT_SYMBOL(can_sock_destruct);
95
96static 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
109static inline void can_put_proto(const struct can_proto *cp)
110{
111 module_put(cp->prot->owner);
112}
113
114static 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 sock->sk = NULL;
175 }
176
177 errout:
178 can_put_proto(cp);
179 return err;
180}
181
182/* af_can tx path */
183
184/**
185 * can_send - transmit a CAN frame (optional with local loopback)
186 * @skb: pointer to socket buffer with CAN frame in data section
187 * @loop: loopback for listeners on local CAN sockets (recommended default!)
188 *
189 * Due to the loopback this routine must not be called from hardirq context.
190 *
191 * Return:
192 * 0 on success
193 * -ENETDOWN when the selected interface is down
194 * -ENOBUFS on full driver queue (see net_xmit_errno())
195 * -ENOMEM when local loopback failed at calling skb_clone()
196 * -EPERM when trying to send on a non-CAN interface
197 * -EMSGSIZE CAN frame size is bigger than CAN interface MTU
198 * -EINVAL when the skb->data does not contain a valid CAN frame
199 */
200int can_send(struct sk_buff *skb, int loop)
201{
202 struct sk_buff *newskb = NULL;
203 struct can_pkg_stats *pkg_stats = dev_net(skb->dev)->can.pkg_stats;
204 int err = -EINVAL;
205
206 if (can_is_canxl_skb(skb)) {
207 skb->protocol = htons(ETH_P_CANXL);
208 } else if (can_is_can_skb(skb)) {
209 skb->protocol = htons(ETH_P_CAN);
210 } else if (can_is_canfd_skb(skb)) {
211 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
212
213 skb->protocol = htons(ETH_P_CANFD);
214
215 /* set CAN FD flag for CAN FD frames by default */
216 cfd->flags |= CANFD_FDF;
217 } else {
218 goto inval_skb;
219 }
220
221 /* Make sure the CAN frame can pass the selected CAN netdevice. */
222 if (unlikely(skb->len > skb->dev->mtu)) {
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
295inval_skb:
296 kfree_skb(skb);
297 return err;
298}
299EXPORT_SYMBOL(can_send);
300
301/* af_can rx path */
302
303static 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 */
326static 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 */
364static 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 */
442int 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
451 /* insert new receiver (dev,canid,mask) -> (func,data) */
452
453 if (dev && (dev->type != ARPHRD_CAN || !can_get_ml_priv(dev)))
454 return -ENODEV;
455
456 if (dev && !net_eq(net, dev_net(dev)))
457 return -ENODEV;
458
459 rcv = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
460 if (!rcv)
461 return -ENOMEM;
462
463 spin_lock_bh(&net->can.rcvlists_lock);
464
465 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
466 rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
467
468 rcv->can_id = can_id;
469 rcv->mask = mask;
470 rcv->matches = 0;
471 rcv->func = func;
472 rcv->data = data;
473 rcv->ident = ident;
474 rcv->sk = sk;
475
476 hlist_add_head_rcu(&rcv->list, rcv_list);
477 dev_rcv_lists->entries++;
478
479 rcv_lists_stats->rcv_entries++;
480 rcv_lists_stats->rcv_entries_max = max(rcv_lists_stats->rcv_entries_max,
481 rcv_lists_stats->rcv_entries);
482 spin_unlock_bh(&net->can.rcvlists_lock);
483
484 return 0;
485}
486EXPORT_SYMBOL(can_rx_register);
487
488/* can_rx_delete_receiver - rcu callback for single receiver entry removal */
489static void can_rx_delete_receiver(struct rcu_head *rp)
490{
491 struct receiver *rcv = container_of(rp, struct receiver, rcu);
492 struct sock *sk = rcv->sk;
493
494 kmem_cache_free(rcv_cache, rcv);
495 if (sk)
496 sock_put(sk);
497}
498
499/**
500 * can_rx_unregister - unsubscribe CAN frames from a specific interface
501 * @net: the applicable net namespace
502 * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
503 * @can_id: CAN identifier
504 * @mask: CAN mask
505 * @func: callback function on filter match
506 * @data: returned parameter for callback function
507 *
508 * Description:
509 * Removes subscription entry depending on given (subscription) values.
510 */
511void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
512 canid_t mask, void (*func)(struct sk_buff *, void *),
513 void *data)
514{
515 struct receiver *rcv = NULL;
516 struct hlist_head *rcv_list;
517 struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
518 struct can_dev_rcv_lists *dev_rcv_lists;
519
520 if (dev && dev->type != ARPHRD_CAN)
521 return;
522
523 if (dev && !net_eq(net, dev_net(dev)))
524 return;
525
526 spin_lock_bh(&net->can.rcvlists_lock);
527
528 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
529 rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
530
531 /* Search the receiver list for the item to delete. This should
532 * exist, since no receiver may be unregistered that hasn't
533 * been registered before.
534 */
535 hlist_for_each_entry_rcu(rcv, rcv_list, list) {
536 if (rcv->can_id == can_id && rcv->mask == mask &&
537 rcv->func == func && rcv->data == data)
538 break;
539 }
540
541 /* Check for bugs in CAN protocol implementations using af_can.c:
542 * 'rcv' will be NULL if no matching list item was found for removal.
543 * As this case may potentially happen when closing a socket while
544 * the notifier for removing the CAN netdev is running we just print
545 * a warning here.
546 */
547 if (!rcv) {
548 pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X\n",
549 DNAME(dev), can_id, mask);
550 goto out;
551 }
552
553 hlist_del_rcu(&rcv->list);
554 dev_rcv_lists->entries--;
555
556 if (rcv_lists_stats->rcv_entries > 0)
557 rcv_lists_stats->rcv_entries--;
558
559 out:
560 spin_unlock_bh(&net->can.rcvlists_lock);
561
562 /* schedule the receiver item for deletion */
563 if (rcv) {
564 if (rcv->sk)
565 sock_hold(rcv->sk);
566 call_rcu(&rcv->rcu, can_rx_delete_receiver);
567 }
568}
569EXPORT_SYMBOL(can_rx_unregister);
570
571static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
572{
573 rcv->func(skb, rcv->data);
574 rcv->matches++;
575}
576
577static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
578{
579 struct receiver *rcv;
580 int matches = 0;
581 struct can_frame *cf = (struct can_frame *)skb->data;
582 canid_t can_id = cf->can_id;
583
584 if (dev_rcv_lists->entries == 0)
585 return 0;
586
587 if (can_id & CAN_ERR_FLAG) {
588 /* check for error message frame entries only */
589 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ERR], list) {
590 if (can_id & rcv->mask) {
591 deliver(skb, rcv);
592 matches++;
593 }
594 }
595 return matches;
596 }
597
598 /* check for unfiltered entries */
599 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ALL], list) {
600 deliver(skb, rcv);
601 matches++;
602 }
603
604 /* check for can_id/mask entries */
605 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_FIL], list) {
606 if ((can_id & rcv->mask) == rcv->can_id) {
607 deliver(skb, rcv);
608 matches++;
609 }
610 }
611
612 /* check for inverted can_id/mask entries */
613 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_INV], list) {
614 if ((can_id & rcv->mask) != rcv->can_id) {
615 deliver(skb, rcv);
616 matches++;
617 }
618 }
619
620 /* check filterlists for single non-RTR can_ids */
621 if (can_id & CAN_RTR_FLAG)
622 return matches;
623
624 if (can_id & CAN_EFF_FLAG) {
625 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_eff[effhash(can_id)], list) {
626 if (rcv->can_id == can_id) {
627 deliver(skb, rcv);
628 matches++;
629 }
630 }
631 } else {
632 can_id &= CAN_SFF_MASK;
633 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_sff[can_id], list) {
634 deliver(skb, rcv);
635 matches++;
636 }
637 }
638
639 return matches;
640}
641
642static void can_receive(struct sk_buff *skb, struct net_device *dev)
643{
644 struct can_dev_rcv_lists *dev_rcv_lists;
645 struct net *net = dev_net(dev);
646 struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
647 int matches;
648
649 /* update statistics */
650 pkg_stats->rx_frames++;
651 pkg_stats->rx_frames_delta++;
652
653 /* create non-zero unique skb identifier together with *skb */
654 while (!(can_skb_prv(skb)->skbcnt))
655 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
656
657 rcu_read_lock();
658
659 /* deliver the packet to sockets listening on all devices */
660 matches = can_rcv_filter(net->can.rx_alldev_list, skb);
661
662 /* find receive list for this device */
663 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
664 matches += can_rcv_filter(dev_rcv_lists, skb);
665
666 rcu_read_unlock();
667
668 /* consume the skbuff allocated by the netdevice driver */
669 consume_skb(skb);
670
671 if (matches > 0) {
672 pkg_stats->matches++;
673 pkg_stats->matches_delta++;
674 }
675}
676
677static int can_rcv(struct sk_buff *skb, struct net_device *dev,
678 struct packet_type *pt, struct net_device *orig_dev)
679{
680 if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_can_skb(skb))) {
681 pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
682 dev->type, skb->len);
683
684 kfree_skb(skb);
685 return NET_RX_DROP;
686 }
687
688 can_receive(skb, dev);
689 return NET_RX_SUCCESS;
690}
691
692static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
693 struct packet_type *pt, struct net_device *orig_dev)
694{
695 if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canfd_skb(skb))) {
696 pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
697 dev->type, skb->len);
698
699 kfree_skb(skb);
700 return NET_RX_DROP;
701 }
702
703 can_receive(skb, dev);
704 return NET_RX_SUCCESS;
705}
706
707static int canxl_rcv(struct sk_buff *skb, struct net_device *dev,
708 struct packet_type *pt, struct net_device *orig_dev)
709{
710 if (unlikely(dev->type != ARPHRD_CAN || !can_get_ml_priv(dev) || !can_is_canxl_skb(skb))) {
711 pr_warn_once("PF_CAN: dropped non conform CAN XL skbuff: dev type %d, len %d\n",
712 dev->type, skb->len);
713
714 kfree_skb(skb);
715 return NET_RX_DROP;
716 }
717
718 can_receive(skb, dev);
719 return NET_RX_SUCCESS;
720}
721
722/* af_can protocol functions */
723
724/**
725 * can_proto_register - register CAN transport protocol
726 * @cp: pointer to CAN protocol structure
727 *
728 * Return:
729 * 0 on success
730 * -EINVAL invalid (out of range) protocol number
731 * -EBUSY protocol already in use
732 * -ENOBUF if proto_register() fails
733 */
734int can_proto_register(const struct can_proto *cp)
735{
736 int proto = cp->protocol;
737 int err = 0;
738
739 if (proto < 0 || proto >= CAN_NPROTO) {
740 pr_err("can: protocol number %d out of range\n", proto);
741 return -EINVAL;
742 }
743
744 err = proto_register(cp->prot, 0);
745 if (err < 0)
746 return err;
747
748 mutex_lock(&proto_tab_lock);
749
750 if (rcu_access_pointer(proto_tab[proto])) {
751 pr_err("can: protocol %d already registered\n", proto);
752 err = -EBUSY;
753 } else {
754 RCU_INIT_POINTER(proto_tab[proto], cp);
755 }
756
757 mutex_unlock(&proto_tab_lock);
758
759 if (err < 0)
760 proto_unregister(cp->prot);
761
762 return err;
763}
764EXPORT_SYMBOL(can_proto_register);
765
766/**
767 * can_proto_unregister - unregister CAN transport protocol
768 * @cp: pointer to CAN protocol structure
769 */
770void can_proto_unregister(const struct can_proto *cp)
771{
772 int proto = cp->protocol;
773
774 mutex_lock(&proto_tab_lock);
775 BUG_ON(rcu_access_pointer(proto_tab[proto]) != cp);
776 RCU_INIT_POINTER(proto_tab[proto], NULL);
777 mutex_unlock(&proto_tab_lock);
778
779 synchronize_rcu();
780
781 proto_unregister(cp->prot);
782}
783EXPORT_SYMBOL(can_proto_unregister);
784
785static int can_pernet_init(struct net *net)
786{
787 spin_lock_init(&net->can.rcvlists_lock);
788 net->can.rx_alldev_list =
789 kzalloc(sizeof(*net->can.rx_alldev_list), GFP_KERNEL);
790 if (!net->can.rx_alldev_list)
791 goto out;
792 net->can.pkg_stats = kzalloc(sizeof(*net->can.pkg_stats), GFP_KERNEL);
793 if (!net->can.pkg_stats)
794 goto out_free_rx_alldev_list;
795 net->can.rcv_lists_stats = kzalloc(sizeof(*net->can.rcv_lists_stats), GFP_KERNEL);
796 if (!net->can.rcv_lists_stats)
797 goto out_free_pkg_stats;
798
799 if (IS_ENABLED(CONFIG_PROC_FS)) {
800 /* the statistics are updated every second (timer triggered) */
801 if (stats_timer) {
802 timer_setup(&net->can.stattimer, can_stat_update,
803 0);
804 mod_timer(&net->can.stattimer,
805 round_jiffies(jiffies + HZ));
806 }
807 net->can.pkg_stats->jiffies_init = jiffies;
808 can_init_proc(net);
809 }
810
811 return 0;
812
813 out_free_pkg_stats:
814 kfree(net->can.pkg_stats);
815 out_free_rx_alldev_list:
816 kfree(net->can.rx_alldev_list);
817 out:
818 return -ENOMEM;
819}
820
821static void can_pernet_exit(struct net *net)
822{
823 if (IS_ENABLED(CONFIG_PROC_FS)) {
824 can_remove_proc(net);
825 if (stats_timer)
826 del_timer_sync(&net->can.stattimer);
827 }
828
829 kfree(net->can.rx_alldev_list);
830 kfree(net->can.pkg_stats);
831 kfree(net->can.rcv_lists_stats);
832}
833
834/* af_can module init/exit functions */
835
836static struct packet_type can_packet __read_mostly = {
837 .type = cpu_to_be16(ETH_P_CAN),
838 .func = can_rcv,
839};
840
841static struct packet_type canfd_packet __read_mostly = {
842 .type = cpu_to_be16(ETH_P_CANFD),
843 .func = canfd_rcv,
844};
845
846static struct packet_type canxl_packet __read_mostly = {
847 .type = cpu_to_be16(ETH_P_CANXL),
848 .func = canxl_rcv,
849};
850
851static const struct net_proto_family can_family_ops = {
852 .family = PF_CAN,
853 .create = can_create,
854 .owner = THIS_MODULE,
855};
856
857static struct pernet_operations can_pernet_ops __read_mostly = {
858 .init = can_pernet_init,
859 .exit = can_pernet_exit,
860};
861
862static __init int can_init(void)
863{
864 int err;
865
866 /* check for correct padding to be able to use the structs similarly */
867 BUILD_BUG_ON(offsetof(struct can_frame, len) !=
868 offsetof(struct canfd_frame, len) ||
869 offsetof(struct can_frame, len) !=
870 offsetof(struct canxl_frame, flags) ||
871 offsetof(struct can_frame, data) !=
872 offsetof(struct canfd_frame, data));
873
874 pr_info("can: controller area network core\n");
875
876 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
877 0, 0, NULL);
878 if (!rcv_cache)
879 return -ENOMEM;
880
881 err = register_pernet_subsys(&can_pernet_ops);
882 if (err)
883 goto out_pernet;
884
885 /* protocol register */
886 err = sock_register(&can_family_ops);
887 if (err)
888 goto out_sock;
889
890 dev_add_pack(&can_packet);
891 dev_add_pack(&canfd_packet);
892 dev_add_pack(&canxl_packet);
893
894 return 0;
895
896out_sock:
897 unregister_pernet_subsys(&can_pernet_ops);
898out_pernet:
899 kmem_cache_destroy(rcv_cache);
900
901 return err;
902}
903
904static __exit void can_exit(void)
905{
906 /* protocol unregister */
907 dev_remove_pack(&canxl_packet);
908 dev_remove_pack(&canfd_packet);
909 dev_remove_pack(&can_packet);
910 sock_unregister(PF_CAN);
911
912 unregister_pernet_subsys(&can_pernet_ops);
913
914 rcu_barrier(); /* Wait for completion of call_rcu()'s */
915
916 kmem_cache_destroy(rcv_cache);
917}
918
919module_init(can_init);
920module_exit(can_exit);
1/*
2 * af_can.c - Protocol family CAN core module
3 * (used by different CAN protocol modules)
4 *
5 * Copyright (c) 2002-2007 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/ratelimit.h>
62#include <net/net_namespace.h>
63#include <net/sock.h>
64
65#include "af_can.h"
66
67MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
68MODULE_LICENSE("Dual BSD/GPL");
69MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
70 "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
71
72MODULE_ALIAS_NETPROTO(PF_CAN);
73
74static int stats_timer __read_mostly = 1;
75module_param(stats_timer, int, S_IRUGO);
76MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
77
78/* receive filters subscribed for 'all' CAN devices */
79struct dev_rcv_lists can_rx_alldev_list;
80static DEFINE_SPINLOCK(can_rcvlists_lock);
81
82static struct kmem_cache *rcv_cache __read_mostly;
83
84/* table of registered CAN protocols */
85static const struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
86static DEFINE_MUTEX(proto_tab_lock);
87
88struct timer_list can_stattimer; /* timer for statistics update */
89struct s_stats can_stats; /* packet statistics */
90struct s_pstats can_pstats; /* receive list statistics */
91
92static atomic_t skbcounter = ATOMIC_INIT(0);
93
94/*
95 * af_can socket functions
96 */
97
98int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
99{
100 struct sock *sk = sock->sk;
101
102 switch (cmd) {
103
104 case SIOCGSTAMP:
105 return sock_get_timestamp(sk, (struct timeval __user *)arg);
106
107 default:
108 return -ENOIOCTLCMD;
109 }
110}
111EXPORT_SYMBOL(can_ioctl);
112
113static void can_sock_destruct(struct sock *sk)
114{
115 skb_queue_purge(&sk->sk_receive_queue);
116}
117
118static const struct can_proto *can_get_proto(int protocol)
119{
120 const struct can_proto *cp;
121
122 rcu_read_lock();
123 cp = rcu_dereference(proto_tab[protocol]);
124 if (cp && !try_module_get(cp->prot->owner))
125 cp = NULL;
126 rcu_read_unlock();
127
128 return cp;
129}
130
131static inline void can_put_proto(const struct can_proto *cp)
132{
133 module_put(cp->prot->owner);
134}
135
136static int can_create(struct net *net, struct socket *sock, int protocol,
137 int kern)
138{
139 struct sock *sk;
140 const struct can_proto *cp;
141 int err = 0;
142
143 sock->state = SS_UNCONNECTED;
144
145 if (protocol < 0 || protocol >= CAN_NPROTO)
146 return -EINVAL;
147
148 if (!net_eq(net, &init_net))
149 return -EAFNOSUPPORT;
150
151 cp = can_get_proto(protocol);
152
153#ifdef CONFIG_MODULES
154 if (!cp) {
155 /* try to load protocol module if kernel is modular */
156
157 err = request_module("can-proto-%d", protocol);
158
159 /*
160 * In case of error we only print a message but don't
161 * return the error code immediately. Below we will
162 * return -EPROTONOSUPPORT
163 */
164 if (err)
165 printk_ratelimited(KERN_ERR "can: request_module "
166 "(can-proto-%d) failed.\n", protocol);
167
168 cp = can_get_proto(protocol);
169 }
170#endif
171
172 /* check for available protocol and correct usage */
173
174 if (!cp)
175 return -EPROTONOSUPPORT;
176
177 if (cp->type != sock->type) {
178 err = -EPROTOTYPE;
179 goto errout;
180 }
181
182 sock->ops = cp->ops;
183
184 sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot, kern);
185 if (!sk) {
186 err = -ENOMEM;
187 goto errout;
188 }
189
190 sock_init_data(sock, sk);
191 sk->sk_destruct = can_sock_destruct;
192
193 if (sk->sk_prot->init)
194 err = sk->sk_prot->init(sk);
195
196 if (err) {
197 /* release sk on errors */
198 sock_orphan(sk);
199 sock_put(sk);
200 }
201
202 errout:
203 can_put_proto(cp);
204 return err;
205}
206
207/*
208 * af_can tx path
209 */
210
211/**
212 * can_send - transmit a CAN frame (optional with local loopback)
213 * @skb: pointer to socket buffer with CAN frame in data section
214 * @loop: loopback for listeners on local CAN sockets (recommended default!)
215 *
216 * Due to the loopback this routine must not be called from hardirq context.
217 *
218 * Return:
219 * 0 on success
220 * -ENETDOWN when the selected interface is down
221 * -ENOBUFS on full driver queue (see net_xmit_errno())
222 * -ENOMEM when local loopback failed at calling skb_clone()
223 * -EPERM when trying to send on a non-CAN interface
224 * -EMSGSIZE CAN frame size is bigger than CAN interface MTU
225 * -EINVAL when the skb->data does not contain a valid CAN frame
226 */
227int can_send(struct sk_buff *skb, int loop)
228{
229 struct sk_buff *newskb = NULL;
230 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
231 int err = -EINVAL;
232
233 if (skb->len == CAN_MTU) {
234 skb->protocol = htons(ETH_P_CAN);
235 if (unlikely(cfd->len > CAN_MAX_DLEN))
236 goto inval_skb;
237 } else if (skb->len == CANFD_MTU) {
238 skb->protocol = htons(ETH_P_CANFD);
239 if (unlikely(cfd->len > CANFD_MAX_DLEN))
240 goto inval_skb;
241 } else
242 goto inval_skb;
243
244 /*
245 * Make sure the CAN frame can pass the selected CAN netdevice.
246 * As structs can_frame and canfd_frame are similar, we can provide
247 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
248 */
249 if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
250 err = -EMSGSIZE;
251 goto inval_skb;
252 }
253
254 if (unlikely(skb->dev->type != ARPHRD_CAN)) {
255 err = -EPERM;
256 goto inval_skb;
257 }
258
259 if (unlikely(!(skb->dev->flags & IFF_UP))) {
260 err = -ENETDOWN;
261 goto inval_skb;
262 }
263
264 skb->ip_summed = CHECKSUM_UNNECESSARY;
265
266 skb_reset_mac_header(skb);
267 skb_reset_network_header(skb);
268 skb_reset_transport_header(skb);
269
270 if (loop) {
271 /* local loopback of sent CAN frames */
272
273 /* indication for the CAN driver: do loopback */
274 skb->pkt_type = PACKET_LOOPBACK;
275
276 /*
277 * The reference to the originating sock may be required
278 * by the receiving socket to check whether the frame is
279 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
280 * Therefore we have to ensure that skb->sk remains the
281 * reference to the originating sock by restoring skb->sk
282 * after each skb_clone() or skb_orphan() usage.
283 */
284
285 if (!(skb->dev->flags & IFF_ECHO)) {
286 /*
287 * If the interface is not capable to do loopback
288 * itself, we do it here.
289 */
290 newskb = skb_clone(skb, GFP_ATOMIC);
291 if (!newskb) {
292 kfree_skb(skb);
293 return -ENOMEM;
294 }
295
296 can_skb_set_owner(newskb, skb->sk);
297 newskb->ip_summed = CHECKSUM_UNNECESSARY;
298 newskb->pkt_type = PACKET_BROADCAST;
299 }
300 } else {
301 /* indication for the CAN driver: no loopback required */
302 skb->pkt_type = PACKET_HOST;
303 }
304
305 /* send to netdevice */
306 err = dev_queue_xmit(skb);
307 if (err > 0)
308 err = net_xmit_errno(err);
309
310 if (err) {
311 kfree_skb(newskb);
312 return err;
313 }
314
315 if (newskb)
316 netif_rx_ni(newskb);
317
318 /* update statistics */
319 can_stats.tx_frames++;
320 can_stats.tx_frames_delta++;
321
322 return 0;
323
324inval_skb:
325 kfree_skb(skb);
326 return err;
327}
328EXPORT_SYMBOL(can_send);
329
330/*
331 * af_can rx path
332 */
333
334static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
335{
336 if (!dev)
337 return &can_rx_alldev_list;
338 else
339 return (struct dev_rcv_lists *)dev->ml_priv;
340}
341
342/**
343 * effhash - hash function for 29 bit CAN identifier reduction
344 * @can_id: 29 bit CAN identifier
345 *
346 * Description:
347 * To reduce the linear traversal in one linked list of _single_ EFF CAN
348 * frame subscriptions the 29 bit identifier is mapped to 10 bits.
349 * (see CAN_EFF_RCV_HASH_BITS definition)
350 *
351 * Return:
352 * Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
353 */
354static unsigned int effhash(canid_t can_id)
355{
356 unsigned int hash;
357
358 hash = can_id;
359 hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
360 hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
361
362 return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
363}
364
365/**
366 * find_rcv_list - determine optimal filterlist inside device filter struct
367 * @can_id: pointer to CAN identifier of a given can_filter
368 * @mask: pointer to CAN mask of a given can_filter
369 * @d: pointer to the device filter struct
370 *
371 * Description:
372 * Returns the optimal filterlist to reduce the filter handling in the
373 * receive path. This function is called by service functions that need
374 * to register or unregister a can_filter in the filter lists.
375 *
376 * A filter matches in general, when
377 *
378 * <received_can_id> & mask == can_id & mask
379 *
380 * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
381 * relevant bits for the filter.
382 *
383 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
384 * filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
385 * frames there is a special filterlist and a special rx path filter handling.
386 *
387 * Return:
388 * Pointer to optimal filterlist for the given can_id/mask pair.
389 * Constistency checked mask.
390 * Reduced can_id to have a preprocessed filter compare value.
391 */
392static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
393 struct dev_rcv_lists *d)
394{
395 canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
396
397 /* filter for error message frames in extra filterlist */
398 if (*mask & CAN_ERR_FLAG) {
399 /* clear CAN_ERR_FLAG in filter entry */
400 *mask &= CAN_ERR_MASK;
401 return &d->rx[RX_ERR];
402 }
403
404 /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
405
406#define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
407
408 /* ensure valid values in can_mask for 'SFF only' frame filtering */
409 if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
410 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
411
412 /* reduce condition testing at receive time */
413 *can_id &= *mask;
414
415 /* inverse can_id/can_mask filter */
416 if (inv)
417 return &d->rx[RX_INV];
418
419 /* mask == 0 => no condition testing at receive time */
420 if (!(*mask))
421 return &d->rx[RX_ALL];
422
423 /* extra filterlists for the subscription of a single non-RTR can_id */
424 if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
425 !(*can_id & CAN_RTR_FLAG)) {
426
427 if (*can_id & CAN_EFF_FLAG) {
428 if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
429 return &d->rx_eff[effhash(*can_id)];
430 } else {
431 if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
432 return &d->rx_sff[*can_id];
433 }
434 }
435
436 /* default: filter via can_id/can_mask */
437 return &d->rx[RX_FIL];
438}
439
440/**
441 * can_rx_register - subscribe CAN frames from a specific interface
442 * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
443 * @can_id: CAN identifier (see description)
444 * @mask: CAN mask (see description)
445 * @func: callback function on filter match
446 * @data: returned parameter for callback function
447 * @ident: string for calling module identification
448 *
449 * Description:
450 * Invokes the callback function with the received sk_buff and the given
451 * parameter 'data' on a matching receive filter. A filter matches, when
452 *
453 * <received_can_id> & mask == can_id & mask
454 *
455 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
456 * filter for error message frames (CAN_ERR_FLAG bit set in mask).
457 *
458 * The provided pointer to the sk_buff is guaranteed to be valid as long as
459 * the callback function is running. The callback function must *not* free
460 * the given sk_buff while processing it's task. When the given sk_buff is
461 * needed after the end of the callback function it must be cloned inside
462 * the callback function with skb_clone().
463 *
464 * Return:
465 * 0 on success
466 * -ENOMEM on missing cache mem to create subscription entry
467 * -ENODEV unknown device
468 */
469int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
470 void (*func)(struct sk_buff *, void *), void *data,
471 char *ident)
472{
473 struct receiver *r;
474 struct hlist_head *rl;
475 struct dev_rcv_lists *d;
476 int err = 0;
477
478 /* insert new receiver (dev,canid,mask) -> (func,data) */
479
480 if (dev && dev->type != ARPHRD_CAN)
481 return -ENODEV;
482
483 r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
484 if (!r)
485 return -ENOMEM;
486
487 spin_lock(&can_rcvlists_lock);
488
489 d = find_dev_rcv_lists(dev);
490 if (d) {
491 rl = find_rcv_list(&can_id, &mask, d);
492
493 r->can_id = can_id;
494 r->mask = mask;
495 r->matches = 0;
496 r->func = func;
497 r->data = data;
498 r->ident = ident;
499
500 hlist_add_head_rcu(&r->list, rl);
501 d->entries++;
502
503 can_pstats.rcv_entries++;
504 if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
505 can_pstats.rcv_entries_max = can_pstats.rcv_entries;
506 } else {
507 kmem_cache_free(rcv_cache, r);
508 err = -ENODEV;
509 }
510
511 spin_unlock(&can_rcvlists_lock);
512
513 return err;
514}
515EXPORT_SYMBOL(can_rx_register);
516
517/*
518 * can_rx_delete_receiver - rcu callback for single receiver entry removal
519 */
520static void can_rx_delete_receiver(struct rcu_head *rp)
521{
522 struct receiver *r = container_of(rp, struct receiver, rcu);
523
524 kmem_cache_free(rcv_cache, r);
525}
526
527/**
528 * can_rx_unregister - unsubscribe CAN frames from a specific interface
529 * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
530 * @can_id: CAN identifier
531 * @mask: CAN mask
532 * @func: callback function on filter match
533 * @data: returned parameter for callback function
534 *
535 * Description:
536 * Removes subscription entry depending on given (subscription) values.
537 */
538void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
539 void (*func)(struct sk_buff *, void *), void *data)
540{
541 struct receiver *r = NULL;
542 struct hlist_head *rl;
543 struct dev_rcv_lists *d;
544
545 if (dev && dev->type != ARPHRD_CAN)
546 return;
547
548 spin_lock(&can_rcvlists_lock);
549
550 d = find_dev_rcv_lists(dev);
551 if (!d) {
552 pr_err("BUG: receive list not found for "
553 "dev %s, id %03X, mask %03X\n",
554 DNAME(dev), can_id, mask);
555 goto out;
556 }
557
558 rl = find_rcv_list(&can_id, &mask, d);
559
560 /*
561 * Search the receiver list for the item to delete. This should
562 * exist, since no receiver may be unregistered that hasn't
563 * been registered before.
564 */
565
566 hlist_for_each_entry_rcu(r, rl, list) {
567 if (r->can_id == can_id && r->mask == mask &&
568 r->func == func && r->data == data)
569 break;
570 }
571
572 /*
573 * Check for bugs in CAN protocol implementations using af_can.c:
574 * 'r' will be NULL if no matching list item was found for removal.
575 */
576
577 if (!r) {
578 WARN(1, "BUG: receive list entry not found for dev %s, "
579 "id %03X, mask %03X\n", DNAME(dev), can_id, mask);
580 goto out;
581 }
582
583 hlist_del_rcu(&r->list);
584 d->entries--;
585
586 if (can_pstats.rcv_entries > 0)
587 can_pstats.rcv_entries--;
588
589 /* remove device structure requested by NETDEV_UNREGISTER */
590 if (d->remove_on_zero_entries && !d->entries) {
591 kfree(d);
592 dev->ml_priv = NULL;
593 }
594
595 out:
596 spin_unlock(&can_rcvlists_lock);
597
598 /* schedule the receiver item for deletion */
599 if (r)
600 call_rcu(&r->rcu, can_rx_delete_receiver);
601}
602EXPORT_SYMBOL(can_rx_unregister);
603
604static inline void deliver(struct sk_buff *skb, struct receiver *r)
605{
606 r->func(skb, r->data);
607 r->matches++;
608}
609
610static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
611{
612 struct receiver *r;
613 int matches = 0;
614 struct can_frame *cf = (struct can_frame *)skb->data;
615 canid_t can_id = cf->can_id;
616
617 if (d->entries == 0)
618 return 0;
619
620 if (can_id & CAN_ERR_FLAG) {
621 /* check for error message frame entries only */
622 hlist_for_each_entry_rcu(r, &d->rx[RX_ERR], list) {
623 if (can_id & r->mask) {
624 deliver(skb, r);
625 matches++;
626 }
627 }
628 return matches;
629 }
630
631 /* check for unfiltered entries */
632 hlist_for_each_entry_rcu(r, &d->rx[RX_ALL], list) {
633 deliver(skb, r);
634 matches++;
635 }
636
637 /* check for can_id/mask entries */
638 hlist_for_each_entry_rcu(r, &d->rx[RX_FIL], list) {
639 if ((can_id & r->mask) == r->can_id) {
640 deliver(skb, r);
641 matches++;
642 }
643 }
644
645 /* check for inverted can_id/mask entries */
646 hlist_for_each_entry_rcu(r, &d->rx[RX_INV], list) {
647 if ((can_id & r->mask) != r->can_id) {
648 deliver(skb, r);
649 matches++;
650 }
651 }
652
653 /* check filterlists for single non-RTR can_ids */
654 if (can_id & CAN_RTR_FLAG)
655 return matches;
656
657 if (can_id & CAN_EFF_FLAG) {
658 hlist_for_each_entry_rcu(r, &d->rx_eff[effhash(can_id)], list) {
659 if (r->can_id == can_id) {
660 deliver(skb, r);
661 matches++;
662 }
663 }
664 } else {
665 can_id &= CAN_SFF_MASK;
666 hlist_for_each_entry_rcu(r, &d->rx_sff[can_id], list) {
667 deliver(skb, r);
668 matches++;
669 }
670 }
671
672 return matches;
673}
674
675static void can_receive(struct sk_buff *skb, struct net_device *dev)
676{
677 struct dev_rcv_lists *d;
678 int matches;
679
680 /* update statistics */
681 can_stats.rx_frames++;
682 can_stats.rx_frames_delta++;
683
684 /* create non-zero unique skb identifier together with *skb */
685 while (!(can_skb_prv(skb)->skbcnt))
686 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
687
688 rcu_read_lock();
689
690 /* deliver the packet to sockets listening on all devices */
691 matches = can_rcv_filter(&can_rx_alldev_list, skb);
692
693 /* find receive list for this device */
694 d = find_dev_rcv_lists(dev);
695 if (d)
696 matches += can_rcv_filter(d, skb);
697
698 rcu_read_unlock();
699
700 /* consume the skbuff allocated by the netdevice driver */
701 consume_skb(skb);
702
703 if (matches > 0) {
704 can_stats.matches++;
705 can_stats.matches_delta++;
706 }
707}
708
709static int can_rcv(struct sk_buff *skb, struct net_device *dev,
710 struct packet_type *pt, struct net_device *orig_dev)
711{
712 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
713
714 if (unlikely(!net_eq(dev_net(dev), &init_net)))
715 goto drop;
716
717 if (WARN_ONCE(dev->type != ARPHRD_CAN ||
718 skb->len != CAN_MTU ||
719 cfd->len > CAN_MAX_DLEN,
720 "PF_CAN: dropped non conform CAN skbuf: "
721 "dev type %d, len %d, datalen %d\n",
722 dev->type, skb->len, cfd->len))
723 goto drop;
724
725 can_receive(skb, dev);
726 return NET_RX_SUCCESS;
727
728drop:
729 kfree_skb(skb);
730 return NET_RX_DROP;
731}
732
733static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
734 struct packet_type *pt, struct net_device *orig_dev)
735{
736 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
737
738 if (unlikely(!net_eq(dev_net(dev), &init_net)))
739 goto drop;
740
741 if (WARN_ONCE(dev->type != ARPHRD_CAN ||
742 skb->len != CANFD_MTU ||
743 cfd->len > CANFD_MAX_DLEN,
744 "PF_CAN: dropped non conform CAN FD skbuf: "
745 "dev type %d, len %d, datalen %d\n",
746 dev->type, skb->len, cfd->len))
747 goto drop;
748
749 can_receive(skb, dev);
750 return NET_RX_SUCCESS;
751
752drop:
753 kfree_skb(skb);
754 return NET_RX_DROP;
755}
756
757/*
758 * af_can protocol functions
759 */
760
761/**
762 * can_proto_register - register CAN transport protocol
763 * @cp: pointer to CAN protocol structure
764 *
765 * Return:
766 * 0 on success
767 * -EINVAL invalid (out of range) protocol number
768 * -EBUSY protocol already in use
769 * -ENOBUF if proto_register() fails
770 */
771int can_proto_register(const struct can_proto *cp)
772{
773 int proto = cp->protocol;
774 int err = 0;
775
776 if (proto < 0 || proto >= CAN_NPROTO) {
777 pr_err("can: protocol number %d out of range\n", proto);
778 return -EINVAL;
779 }
780
781 err = proto_register(cp->prot, 0);
782 if (err < 0)
783 return err;
784
785 mutex_lock(&proto_tab_lock);
786
787 if (proto_tab[proto]) {
788 pr_err("can: protocol %d already registered\n", proto);
789 err = -EBUSY;
790 } else
791 RCU_INIT_POINTER(proto_tab[proto], cp);
792
793 mutex_unlock(&proto_tab_lock);
794
795 if (err < 0)
796 proto_unregister(cp->prot);
797
798 return err;
799}
800EXPORT_SYMBOL(can_proto_register);
801
802/**
803 * can_proto_unregister - unregister CAN transport protocol
804 * @cp: pointer to CAN protocol structure
805 */
806void can_proto_unregister(const struct can_proto *cp)
807{
808 int proto = cp->protocol;
809
810 mutex_lock(&proto_tab_lock);
811 BUG_ON(proto_tab[proto] != cp);
812 RCU_INIT_POINTER(proto_tab[proto], NULL);
813 mutex_unlock(&proto_tab_lock);
814
815 synchronize_rcu();
816
817 proto_unregister(cp->prot);
818}
819EXPORT_SYMBOL(can_proto_unregister);
820
821/*
822 * af_can notifier to create/remove CAN netdevice specific structs
823 */
824static int can_notifier(struct notifier_block *nb, unsigned long msg,
825 void *ptr)
826{
827 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
828 struct dev_rcv_lists *d;
829
830 if (!net_eq(dev_net(dev), &init_net))
831 return NOTIFY_DONE;
832
833 if (dev->type != ARPHRD_CAN)
834 return NOTIFY_DONE;
835
836 switch (msg) {
837
838 case NETDEV_REGISTER:
839
840 /* create new dev_rcv_lists for this device */
841 d = kzalloc(sizeof(*d), GFP_KERNEL);
842 if (!d)
843 return NOTIFY_DONE;
844 BUG_ON(dev->ml_priv);
845 dev->ml_priv = d;
846
847 break;
848
849 case NETDEV_UNREGISTER:
850 spin_lock(&can_rcvlists_lock);
851
852 d = dev->ml_priv;
853 if (d) {
854 if (d->entries)
855 d->remove_on_zero_entries = 1;
856 else {
857 kfree(d);
858 dev->ml_priv = NULL;
859 }
860 } else
861 pr_err("can: notifier: receive list not found for dev "
862 "%s\n", dev->name);
863
864 spin_unlock(&can_rcvlists_lock);
865
866 break;
867 }
868
869 return NOTIFY_DONE;
870}
871
872/*
873 * af_can module init/exit functions
874 */
875
876static struct packet_type can_packet __read_mostly = {
877 .type = cpu_to_be16(ETH_P_CAN),
878 .func = can_rcv,
879};
880
881static struct packet_type canfd_packet __read_mostly = {
882 .type = cpu_to_be16(ETH_P_CANFD),
883 .func = canfd_rcv,
884};
885
886static const struct net_proto_family can_family_ops = {
887 .family = PF_CAN,
888 .create = can_create,
889 .owner = THIS_MODULE,
890};
891
892/* notifier block for netdevice event */
893static struct notifier_block can_netdev_notifier __read_mostly = {
894 .notifier_call = can_notifier,
895};
896
897static __init int can_init(void)
898{
899 /* check for correct padding to be able to use the structs similarly */
900 BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
901 offsetof(struct canfd_frame, len) ||
902 offsetof(struct can_frame, data) !=
903 offsetof(struct canfd_frame, data));
904
905 pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
906
907 memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
908
909 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
910 0, 0, NULL);
911 if (!rcv_cache)
912 return -ENOMEM;
913
914 if (stats_timer) {
915 /* the statistics are updated every second (timer triggered) */
916 setup_timer(&can_stattimer, can_stat_update, 0);
917 mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
918 } else
919 can_stattimer.function = NULL;
920
921 can_init_proc();
922
923 /* protocol register */
924 sock_register(&can_family_ops);
925 register_netdevice_notifier(&can_netdev_notifier);
926 dev_add_pack(&can_packet);
927 dev_add_pack(&canfd_packet);
928
929 return 0;
930}
931
932static __exit void can_exit(void)
933{
934 struct net_device *dev;
935
936 if (stats_timer)
937 del_timer_sync(&can_stattimer);
938
939 can_remove_proc();
940
941 /* protocol unregister */
942 dev_remove_pack(&canfd_packet);
943 dev_remove_pack(&can_packet);
944 unregister_netdevice_notifier(&can_netdev_notifier);
945 sock_unregister(PF_CAN);
946
947 /* remove created dev_rcv_lists from still registered CAN devices */
948 rcu_read_lock();
949 for_each_netdev_rcu(&init_net, dev) {
950 if (dev->type == ARPHRD_CAN && dev->ml_priv) {
951
952 struct dev_rcv_lists *d = dev->ml_priv;
953
954 BUG_ON(d->entries);
955 kfree(d);
956 dev->ml_priv = NULL;
957 }
958 }
959 rcu_read_unlock();
960
961 rcu_barrier(); /* Wait for completion of call_rcu()'s */
962
963 kmem_cache_destroy(rcv_cache);
964}
965
966module_init(can_init);
967module_exit(can_exit);