Loading...
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/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 * @sk: socket pointer (might be NULL)
449 *
450 * Description:
451 * Invokes the callback function with the received sk_buff and the given
452 * parameter 'data' on a matching receive filter. A filter matches, when
453 *
454 * <received_can_id> & mask == can_id & mask
455 *
456 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
457 * filter for error message frames (CAN_ERR_FLAG bit set in mask).
458 *
459 * The provided pointer to the sk_buff is guaranteed to be valid as long as
460 * the callback function is running. The callback function must *not* free
461 * the given sk_buff while processing it's task. When the given sk_buff is
462 * needed after the end of the callback function it must be cloned inside
463 * the callback function with skb_clone().
464 *
465 * Return:
466 * 0 on success
467 * -ENOMEM on missing cache mem to create subscription entry
468 * -ENODEV unknown device
469 */
470int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
471 void (*func)(struct sk_buff *, void *), void *data,
472 char *ident, struct sock *sk)
473{
474 struct receiver *r;
475 struct hlist_head *rl;
476 struct dev_rcv_lists *d;
477 int err = 0;
478
479 /* insert new receiver (dev,canid,mask) -> (func,data) */
480
481 if (dev && dev->type != ARPHRD_CAN)
482 return -ENODEV;
483
484 r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
485 if (!r)
486 return -ENOMEM;
487
488 spin_lock(&can_rcvlists_lock);
489
490 d = find_dev_rcv_lists(dev);
491 if (d) {
492 rl = find_rcv_list(&can_id, &mask, d);
493
494 r->can_id = can_id;
495 r->mask = mask;
496 r->matches = 0;
497 r->func = func;
498 r->data = data;
499 r->ident = ident;
500 r->sk = sk;
501
502 hlist_add_head_rcu(&r->list, rl);
503 d->entries++;
504
505 can_pstats.rcv_entries++;
506 if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
507 can_pstats.rcv_entries_max = can_pstats.rcv_entries;
508 } else {
509 kmem_cache_free(rcv_cache, r);
510 err = -ENODEV;
511 }
512
513 spin_unlock(&can_rcvlists_lock);
514
515 return err;
516}
517EXPORT_SYMBOL(can_rx_register);
518
519/*
520 * can_rx_delete_receiver - rcu callback for single receiver entry removal
521 */
522static void can_rx_delete_receiver(struct rcu_head *rp)
523{
524 struct receiver *r = container_of(rp, struct receiver, rcu);
525 struct sock *sk = r->sk;
526
527 kmem_cache_free(rcv_cache, r);
528 if (sk)
529 sock_put(sk);
530}
531
532/**
533 * can_rx_unregister - unsubscribe CAN frames from a specific interface
534 * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
535 * @can_id: CAN identifier
536 * @mask: CAN mask
537 * @func: callback function on filter match
538 * @data: returned parameter for callback function
539 *
540 * Description:
541 * Removes subscription entry depending on given (subscription) values.
542 */
543void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
544 void (*func)(struct sk_buff *, void *), void *data)
545{
546 struct receiver *r = NULL;
547 struct hlist_head *rl;
548 struct dev_rcv_lists *d;
549
550 if (dev && dev->type != ARPHRD_CAN)
551 return;
552
553 spin_lock(&can_rcvlists_lock);
554
555 d = find_dev_rcv_lists(dev);
556 if (!d) {
557 pr_err("BUG: receive list not found for "
558 "dev %s, id %03X, mask %03X\n",
559 DNAME(dev), can_id, mask);
560 goto out;
561 }
562
563 rl = find_rcv_list(&can_id, &mask, d);
564
565 /*
566 * Search the receiver list for the item to delete. This should
567 * exist, since no receiver may be unregistered that hasn't
568 * been registered before.
569 */
570
571 hlist_for_each_entry_rcu(r, rl, list) {
572 if (r->can_id == can_id && r->mask == mask &&
573 r->func == func && r->data == data)
574 break;
575 }
576
577 /*
578 * Check for bugs in CAN protocol implementations using af_can.c:
579 * 'r' will be NULL if no matching list item was found for removal.
580 */
581
582 if (!r) {
583 WARN(1, "BUG: receive list entry not found for dev %s, "
584 "id %03X, mask %03X\n", DNAME(dev), can_id, mask);
585 goto out;
586 }
587
588 hlist_del_rcu(&r->list);
589 d->entries--;
590
591 if (can_pstats.rcv_entries > 0)
592 can_pstats.rcv_entries--;
593
594 /* remove device structure requested by NETDEV_UNREGISTER */
595 if (d->remove_on_zero_entries && !d->entries) {
596 kfree(d);
597 dev->ml_priv = NULL;
598 }
599
600 out:
601 spin_unlock(&can_rcvlists_lock);
602
603 /* schedule the receiver item for deletion */
604 if (r) {
605 if (r->sk)
606 sock_hold(r->sk);
607 call_rcu(&r->rcu, can_rx_delete_receiver);
608 }
609}
610EXPORT_SYMBOL(can_rx_unregister);
611
612static inline void deliver(struct sk_buff *skb, struct receiver *r)
613{
614 r->func(skb, r->data);
615 r->matches++;
616}
617
618static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
619{
620 struct receiver *r;
621 int matches = 0;
622 struct can_frame *cf = (struct can_frame *)skb->data;
623 canid_t can_id = cf->can_id;
624
625 if (d->entries == 0)
626 return 0;
627
628 if (can_id & CAN_ERR_FLAG) {
629 /* check for error message frame entries only */
630 hlist_for_each_entry_rcu(r, &d->rx[RX_ERR], list) {
631 if (can_id & r->mask) {
632 deliver(skb, r);
633 matches++;
634 }
635 }
636 return matches;
637 }
638
639 /* check for unfiltered entries */
640 hlist_for_each_entry_rcu(r, &d->rx[RX_ALL], list) {
641 deliver(skb, r);
642 matches++;
643 }
644
645 /* check for can_id/mask entries */
646 hlist_for_each_entry_rcu(r, &d->rx[RX_FIL], list) {
647 if ((can_id & r->mask) == r->can_id) {
648 deliver(skb, r);
649 matches++;
650 }
651 }
652
653 /* check for inverted can_id/mask entries */
654 hlist_for_each_entry_rcu(r, &d->rx[RX_INV], list) {
655 if ((can_id & r->mask) != r->can_id) {
656 deliver(skb, r);
657 matches++;
658 }
659 }
660
661 /* check filterlists for single non-RTR can_ids */
662 if (can_id & CAN_RTR_FLAG)
663 return matches;
664
665 if (can_id & CAN_EFF_FLAG) {
666 hlist_for_each_entry_rcu(r, &d->rx_eff[effhash(can_id)], list) {
667 if (r->can_id == can_id) {
668 deliver(skb, r);
669 matches++;
670 }
671 }
672 } else {
673 can_id &= CAN_SFF_MASK;
674 hlist_for_each_entry_rcu(r, &d->rx_sff[can_id], list) {
675 deliver(skb, r);
676 matches++;
677 }
678 }
679
680 return matches;
681}
682
683static void can_receive(struct sk_buff *skb, struct net_device *dev)
684{
685 struct dev_rcv_lists *d;
686 int matches;
687
688 /* update statistics */
689 can_stats.rx_frames++;
690 can_stats.rx_frames_delta++;
691
692 /* create non-zero unique skb identifier together with *skb */
693 while (!(can_skb_prv(skb)->skbcnt))
694 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
695
696 rcu_read_lock();
697
698 /* deliver the packet to sockets listening on all devices */
699 matches = can_rcv_filter(&can_rx_alldev_list, skb);
700
701 /* find receive list for this device */
702 d = find_dev_rcv_lists(dev);
703 if (d)
704 matches += can_rcv_filter(d, skb);
705
706 rcu_read_unlock();
707
708 /* consume the skbuff allocated by the netdevice driver */
709 consume_skb(skb);
710
711 if (matches > 0) {
712 can_stats.matches++;
713 can_stats.matches_delta++;
714 }
715}
716
717static int can_rcv(struct sk_buff *skb, struct net_device *dev,
718 struct packet_type *pt, struct net_device *orig_dev)
719{
720 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
721
722 if (unlikely(!net_eq(dev_net(dev), &init_net)))
723 goto drop;
724
725 if (WARN_ONCE(dev->type != ARPHRD_CAN ||
726 skb->len != CAN_MTU ||
727 cfd->len > CAN_MAX_DLEN,
728 "PF_CAN: dropped non conform CAN skbuf: "
729 "dev type %d, len %d, datalen %d\n",
730 dev->type, skb->len, cfd->len))
731 goto drop;
732
733 can_receive(skb, dev);
734 return NET_RX_SUCCESS;
735
736drop:
737 kfree_skb(skb);
738 return NET_RX_DROP;
739}
740
741static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
742 struct packet_type *pt, struct net_device *orig_dev)
743{
744 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
745
746 if (unlikely(!net_eq(dev_net(dev), &init_net)))
747 goto drop;
748
749 if (WARN_ONCE(dev->type != ARPHRD_CAN ||
750 skb->len != CANFD_MTU ||
751 cfd->len > CANFD_MAX_DLEN,
752 "PF_CAN: dropped non conform CAN FD skbuf: "
753 "dev type %d, len %d, datalen %d\n",
754 dev->type, skb->len, cfd->len))
755 goto drop;
756
757 can_receive(skb, dev);
758 return NET_RX_SUCCESS;
759
760drop:
761 kfree_skb(skb);
762 return NET_RX_DROP;
763}
764
765/*
766 * af_can protocol functions
767 */
768
769/**
770 * can_proto_register - register CAN transport protocol
771 * @cp: pointer to CAN protocol structure
772 *
773 * Return:
774 * 0 on success
775 * -EINVAL invalid (out of range) protocol number
776 * -EBUSY protocol already in use
777 * -ENOBUF if proto_register() fails
778 */
779int can_proto_register(const struct can_proto *cp)
780{
781 int proto = cp->protocol;
782 int err = 0;
783
784 if (proto < 0 || proto >= CAN_NPROTO) {
785 pr_err("can: protocol number %d out of range\n", proto);
786 return -EINVAL;
787 }
788
789 err = proto_register(cp->prot, 0);
790 if (err < 0)
791 return err;
792
793 mutex_lock(&proto_tab_lock);
794
795 if (proto_tab[proto]) {
796 pr_err("can: protocol %d already registered\n", proto);
797 err = -EBUSY;
798 } else
799 RCU_INIT_POINTER(proto_tab[proto], cp);
800
801 mutex_unlock(&proto_tab_lock);
802
803 if (err < 0)
804 proto_unregister(cp->prot);
805
806 return err;
807}
808EXPORT_SYMBOL(can_proto_register);
809
810/**
811 * can_proto_unregister - unregister CAN transport protocol
812 * @cp: pointer to CAN protocol structure
813 */
814void can_proto_unregister(const struct can_proto *cp)
815{
816 int proto = cp->protocol;
817
818 mutex_lock(&proto_tab_lock);
819 BUG_ON(proto_tab[proto] != cp);
820 RCU_INIT_POINTER(proto_tab[proto], NULL);
821 mutex_unlock(&proto_tab_lock);
822
823 synchronize_rcu();
824
825 proto_unregister(cp->prot);
826}
827EXPORT_SYMBOL(can_proto_unregister);
828
829/*
830 * af_can notifier to create/remove CAN netdevice specific structs
831 */
832static int can_notifier(struct notifier_block *nb, unsigned long msg,
833 void *ptr)
834{
835 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
836 struct dev_rcv_lists *d;
837
838 if (!net_eq(dev_net(dev), &init_net))
839 return NOTIFY_DONE;
840
841 if (dev->type != ARPHRD_CAN)
842 return NOTIFY_DONE;
843
844 switch (msg) {
845
846 case NETDEV_REGISTER:
847
848 /* create new dev_rcv_lists for this device */
849 d = kzalloc(sizeof(*d), GFP_KERNEL);
850 if (!d)
851 return NOTIFY_DONE;
852 BUG_ON(dev->ml_priv);
853 dev->ml_priv = d;
854
855 break;
856
857 case NETDEV_UNREGISTER:
858 spin_lock(&can_rcvlists_lock);
859
860 d = dev->ml_priv;
861 if (d) {
862 if (d->entries)
863 d->remove_on_zero_entries = 1;
864 else {
865 kfree(d);
866 dev->ml_priv = NULL;
867 }
868 } else
869 pr_err("can: notifier: receive list not found for dev "
870 "%s\n", dev->name);
871
872 spin_unlock(&can_rcvlists_lock);
873
874 break;
875 }
876
877 return NOTIFY_DONE;
878}
879
880/*
881 * af_can module init/exit functions
882 */
883
884static struct packet_type can_packet __read_mostly = {
885 .type = cpu_to_be16(ETH_P_CAN),
886 .func = can_rcv,
887};
888
889static struct packet_type canfd_packet __read_mostly = {
890 .type = cpu_to_be16(ETH_P_CANFD),
891 .func = canfd_rcv,
892};
893
894static const struct net_proto_family can_family_ops = {
895 .family = PF_CAN,
896 .create = can_create,
897 .owner = THIS_MODULE,
898};
899
900/* notifier block for netdevice event */
901static struct notifier_block can_netdev_notifier __read_mostly = {
902 .notifier_call = can_notifier,
903};
904
905static __init int can_init(void)
906{
907 /* check for correct padding to be able to use the structs similarly */
908 BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
909 offsetof(struct canfd_frame, len) ||
910 offsetof(struct can_frame, data) !=
911 offsetof(struct canfd_frame, data));
912
913 pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
914
915 memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
916
917 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
918 0, 0, NULL);
919 if (!rcv_cache)
920 return -ENOMEM;
921
922 if (IS_ENABLED(CONFIG_PROC_FS)) {
923 if (stats_timer) {
924 /* the statistics are updated every second (timer triggered) */
925 setup_timer(&can_stattimer, can_stat_update, 0);
926 mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
927 }
928 can_init_proc();
929 }
930
931 /* protocol register */
932 sock_register(&can_family_ops);
933 register_netdevice_notifier(&can_netdev_notifier);
934 dev_add_pack(&can_packet);
935 dev_add_pack(&canfd_packet);
936
937 return 0;
938}
939
940static __exit void can_exit(void)
941{
942 struct net_device *dev;
943
944 if (IS_ENABLED(CONFIG_PROC_FS)) {
945 if (stats_timer)
946 del_timer_sync(&can_stattimer);
947
948 can_remove_proc();
949 }
950
951 /* protocol unregister */
952 dev_remove_pack(&canfd_packet);
953 dev_remove_pack(&can_packet);
954 unregister_netdevice_notifier(&can_netdev_notifier);
955 sock_unregister(PF_CAN);
956
957 /* remove created dev_rcv_lists from still registered CAN devices */
958 rcu_read_lock();
959 for_each_netdev_rcu(&init_net, dev) {
960 if (dev->type == ARPHRD_CAN && dev->ml_priv) {
961
962 struct dev_rcv_lists *d = dev->ml_priv;
963
964 BUG_ON(d->entries);
965 kfree(d);
966 dev->ml_priv = NULL;
967 }
968 }
969 rcu_read_unlock();
970
971 rcu_barrier(); /* Wait for completion of call_rcu()'s */
972
973 kmem_cache_destroy(rcv_cache);
974}
975
976module_init(can_init);
977module_exit(can_exit);