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