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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 canfd_frame *cfd = (struct canfd_frame *)skb->data;
203 struct can_pkg_stats *pkg_stats = dev_net(skb->dev)->can.pkg_stats;
204 int err = -EINVAL;
205
206 if (skb->len == CAN_MTU) {
207 skb->protocol = htons(ETH_P_CAN);
208 if (unlikely(cfd->len > CAN_MAX_DLEN))
209 goto inval_skb;
210 } else if (skb->len == CANFD_MTU) {
211 skb->protocol = htons(ETH_P_CANFD);
212 if (unlikely(cfd->len > CANFD_MAX_DLEN))
213 goto inval_skb;
214 } else {
215 goto inval_skb;
216 }
217
218 /* Make sure the CAN frame can pass the selected CAN netdevice.
219 * As structs can_frame and canfd_frame are similar, we can provide
220 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
221 */
222 if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
223 err = -EMSGSIZE;
224 goto inval_skb;
225 }
226
227 if (unlikely(skb->dev->type != ARPHRD_CAN)) {
228 err = -EPERM;
229 goto inval_skb;
230 }
231
232 if (unlikely(!(skb->dev->flags & IFF_UP))) {
233 err = -ENETDOWN;
234 goto inval_skb;
235 }
236
237 skb->ip_summed = CHECKSUM_UNNECESSARY;
238
239 skb_reset_mac_header(skb);
240 skb_reset_network_header(skb);
241 skb_reset_transport_header(skb);
242
243 if (loop) {
244 /* local loopback of sent CAN frames */
245
246 /* indication for the CAN driver: do loopback */
247 skb->pkt_type = PACKET_LOOPBACK;
248
249 /* The reference to the originating sock may be required
250 * by the receiving socket to check whether the frame is
251 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
252 * Therefore we have to ensure that skb->sk remains the
253 * reference to the originating sock by restoring skb->sk
254 * after each skb_clone() or skb_orphan() usage.
255 */
256
257 if (!(skb->dev->flags & IFF_ECHO)) {
258 /* If the interface is not capable to do loopback
259 * itself, we do it here.
260 */
261 newskb = skb_clone(skb, GFP_ATOMIC);
262 if (!newskb) {
263 kfree_skb(skb);
264 return -ENOMEM;
265 }
266
267 can_skb_set_owner(newskb, skb->sk);
268 newskb->ip_summed = CHECKSUM_UNNECESSARY;
269 newskb->pkt_type = PACKET_BROADCAST;
270 }
271 } else {
272 /* indication for the CAN driver: no loopback required */
273 skb->pkt_type = PACKET_HOST;
274 }
275
276 /* send to netdevice */
277 err = dev_queue_xmit(skb);
278 if (err > 0)
279 err = net_xmit_errno(err);
280
281 if (err) {
282 kfree_skb(newskb);
283 return err;
284 }
285
286 if (newskb)
287 netif_rx_ni(newskb);
288
289 /* update statistics */
290 pkg_stats->tx_frames++;
291 pkg_stats->tx_frames_delta++;
292
293 return 0;
294
295inval_skb:
296 kfree_skb(skb);
297 return err;
298}
299EXPORT_SYMBOL(can_send);
300
301/* af_can rx path */
302
303static struct can_dev_rcv_lists *can_dev_rcv_lists_find(struct net *net,
304 struct net_device *dev)
305{
306 if (dev) {
307 struct can_ml_priv *can_ml = can_get_ml_priv(dev);
308 return &can_ml->dev_rcv_lists;
309 } else {
310 return net->can.rx_alldev_list;
311 }
312}
313
314/**
315 * effhash - hash function for 29 bit CAN identifier reduction
316 * @can_id: 29 bit CAN identifier
317 *
318 * Description:
319 * To reduce the linear traversal in one linked list of _single_ EFF CAN
320 * frame subscriptions the 29 bit identifier is mapped to 10 bits.
321 * (see CAN_EFF_RCV_HASH_BITS definition)
322 *
323 * Return:
324 * Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
325 */
326static unsigned int effhash(canid_t can_id)
327{
328 unsigned int hash;
329
330 hash = can_id;
331 hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
332 hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
333
334 return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
335}
336
337/**
338 * can_rcv_list_find - determine optimal filterlist inside device filter struct
339 * @can_id: pointer to CAN identifier of a given can_filter
340 * @mask: pointer to CAN mask of a given can_filter
341 * @dev_rcv_lists: pointer to the device filter struct
342 *
343 * Description:
344 * Returns the optimal filterlist to reduce the filter handling in the
345 * receive path. This function is called by service functions that need
346 * to register or unregister a can_filter in the filter lists.
347 *
348 * A filter matches in general, when
349 *
350 * <received_can_id> & mask == can_id & mask
351 *
352 * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
353 * relevant bits for the filter.
354 *
355 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
356 * filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
357 * frames there is a special filterlist and a special rx path filter handling.
358 *
359 * Return:
360 * Pointer to optimal filterlist for the given can_id/mask pair.
361 * Consistency checked mask.
362 * Reduced can_id to have a preprocessed filter compare value.
363 */
364static struct hlist_head *can_rcv_list_find(canid_t *can_id, canid_t *mask,
365 struct can_dev_rcv_lists *dev_rcv_lists)
366{
367 canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
368
369 /* filter for error message frames in extra filterlist */
370 if (*mask & CAN_ERR_FLAG) {
371 /* clear CAN_ERR_FLAG in filter entry */
372 *mask &= CAN_ERR_MASK;
373 return &dev_rcv_lists->rx[RX_ERR];
374 }
375
376 /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
377
378#define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
379
380 /* ensure valid values in can_mask for 'SFF only' frame filtering */
381 if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
382 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
383
384 /* reduce condition testing at receive time */
385 *can_id &= *mask;
386
387 /* inverse can_id/can_mask filter */
388 if (inv)
389 return &dev_rcv_lists->rx[RX_INV];
390
391 /* mask == 0 => no condition testing at receive time */
392 if (!(*mask))
393 return &dev_rcv_lists->rx[RX_ALL];
394
395 /* extra filterlists for the subscription of a single non-RTR can_id */
396 if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
397 !(*can_id & CAN_RTR_FLAG)) {
398 if (*can_id & CAN_EFF_FLAG) {
399 if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
400 return &dev_rcv_lists->rx_eff[effhash(*can_id)];
401 } else {
402 if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
403 return &dev_rcv_lists->rx_sff[*can_id];
404 }
405 }
406
407 /* default: filter via can_id/can_mask */
408 return &dev_rcv_lists->rx[RX_FIL];
409}
410
411/**
412 * can_rx_register - subscribe CAN frames from a specific interface
413 * @net: the applicable net namespace
414 * @dev: pointer to netdevice (NULL => subscribe from 'all' CAN devices list)
415 * @can_id: CAN identifier (see description)
416 * @mask: CAN mask (see description)
417 * @func: callback function on filter match
418 * @data: returned parameter for callback function
419 * @ident: string for calling module identification
420 * @sk: socket pointer (might be NULL)
421 *
422 * Description:
423 * Invokes the callback function with the received sk_buff and the given
424 * parameter 'data' on a matching receive filter. A filter matches, when
425 *
426 * <received_can_id> & mask == can_id & mask
427 *
428 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
429 * filter for error message frames (CAN_ERR_FLAG bit set in mask).
430 *
431 * The provided pointer to the sk_buff is guaranteed to be valid as long as
432 * the callback function is running. The callback function must *not* free
433 * the given sk_buff while processing it's task. When the given sk_buff is
434 * needed after the end of the callback function it must be cloned inside
435 * the callback function with skb_clone().
436 *
437 * Return:
438 * 0 on success
439 * -ENOMEM on missing cache mem to create subscription entry
440 * -ENODEV unknown device
441 */
442int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
443 canid_t mask, void (*func)(struct sk_buff *, void *),
444 void *data, char *ident, struct sock *sk)
445{
446 struct receiver *rcv;
447 struct hlist_head *rcv_list;
448 struct can_dev_rcv_lists *dev_rcv_lists;
449 struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
450 int err = 0;
451
452 /* insert new receiver (dev,canid,mask) -> (func,data) */
453
454 if (dev && dev->type != ARPHRD_CAN)
455 return -ENODEV;
456
457 if (dev && !net_eq(net, dev_net(dev)))
458 return -ENODEV;
459
460 rcv = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
461 if (!rcv)
462 return -ENOMEM;
463
464 spin_lock_bh(&net->can.rcvlists_lock);
465
466 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
467 rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
468
469 rcv->can_id = can_id;
470 rcv->mask = mask;
471 rcv->matches = 0;
472 rcv->func = func;
473 rcv->data = data;
474 rcv->ident = ident;
475 rcv->sk = sk;
476
477 hlist_add_head_rcu(&rcv->list, rcv_list);
478 dev_rcv_lists->entries++;
479
480 rcv_lists_stats->rcv_entries++;
481 rcv_lists_stats->rcv_entries_max = max(rcv_lists_stats->rcv_entries_max,
482 rcv_lists_stats->rcv_entries);
483 spin_unlock_bh(&net->can.rcvlists_lock);
484
485 return err;
486}
487EXPORT_SYMBOL(can_rx_register);
488
489/* can_rx_delete_receiver - rcu callback for single receiver entry removal */
490static void can_rx_delete_receiver(struct rcu_head *rp)
491{
492 struct receiver *rcv = container_of(rp, struct receiver, rcu);
493 struct sock *sk = rcv->sk;
494
495 kmem_cache_free(rcv_cache, rcv);
496 if (sk)
497 sock_put(sk);
498}
499
500/**
501 * can_rx_unregister - unsubscribe CAN frames from a specific interface
502 * @net: the applicable net namespace
503 * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
504 * @can_id: CAN identifier
505 * @mask: CAN mask
506 * @func: callback function on filter match
507 * @data: returned parameter for callback function
508 *
509 * Description:
510 * Removes subscription entry depending on given (subscription) values.
511 */
512void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
513 canid_t mask, void (*func)(struct sk_buff *, void *),
514 void *data)
515{
516 struct receiver *rcv = NULL;
517 struct hlist_head *rcv_list;
518 struct can_rcv_lists_stats *rcv_lists_stats = net->can.rcv_lists_stats;
519 struct can_dev_rcv_lists *dev_rcv_lists;
520
521 if (dev && dev->type != ARPHRD_CAN)
522 return;
523
524 if (dev && !net_eq(net, dev_net(dev)))
525 return;
526
527 spin_lock_bh(&net->can.rcvlists_lock);
528
529 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
530 rcv_list = can_rcv_list_find(&can_id, &mask, dev_rcv_lists);
531
532 /* Search the receiver list for the item to delete. This should
533 * exist, since no receiver may be unregistered that hasn't
534 * been registered before.
535 */
536 hlist_for_each_entry_rcu(rcv, rcv_list, list) {
537 if (rcv->can_id == can_id && rcv->mask == mask &&
538 rcv->func == func && rcv->data == data)
539 break;
540 }
541
542 /* Check for bugs in CAN protocol implementations using af_can.c:
543 * 'rcv' will be NULL if no matching list item was found for removal.
544 * As this case may potentially happen when closing a socket while
545 * the notifier for removing the CAN netdev is running we just print
546 * a warning here.
547 */
548 if (!rcv) {
549 pr_warn("can: receive list entry not found for dev %s, id %03X, mask %03X\n",
550 DNAME(dev), can_id, mask);
551 goto out;
552 }
553
554 hlist_del_rcu(&rcv->list);
555 dev_rcv_lists->entries--;
556
557 if (rcv_lists_stats->rcv_entries > 0)
558 rcv_lists_stats->rcv_entries--;
559
560 out:
561 spin_unlock_bh(&net->can.rcvlists_lock);
562
563 /* schedule the receiver item for deletion */
564 if (rcv) {
565 if (rcv->sk)
566 sock_hold(rcv->sk);
567 call_rcu(&rcv->rcu, can_rx_delete_receiver);
568 }
569}
570EXPORT_SYMBOL(can_rx_unregister);
571
572static inline void deliver(struct sk_buff *skb, struct receiver *rcv)
573{
574 rcv->func(skb, rcv->data);
575 rcv->matches++;
576}
577
578static int can_rcv_filter(struct can_dev_rcv_lists *dev_rcv_lists, struct sk_buff *skb)
579{
580 struct receiver *rcv;
581 int matches = 0;
582 struct can_frame *cf = (struct can_frame *)skb->data;
583 canid_t can_id = cf->can_id;
584
585 if (dev_rcv_lists->entries == 0)
586 return 0;
587
588 if (can_id & CAN_ERR_FLAG) {
589 /* check for error message frame entries only */
590 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ERR], list) {
591 if (can_id & rcv->mask) {
592 deliver(skb, rcv);
593 matches++;
594 }
595 }
596 return matches;
597 }
598
599 /* check for unfiltered entries */
600 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_ALL], list) {
601 deliver(skb, rcv);
602 matches++;
603 }
604
605 /* check for can_id/mask entries */
606 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_FIL], list) {
607 if ((can_id & rcv->mask) == rcv->can_id) {
608 deliver(skb, rcv);
609 matches++;
610 }
611 }
612
613 /* check for inverted can_id/mask entries */
614 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx[RX_INV], list) {
615 if ((can_id & rcv->mask) != rcv->can_id) {
616 deliver(skb, rcv);
617 matches++;
618 }
619 }
620
621 /* check filterlists for single non-RTR can_ids */
622 if (can_id & CAN_RTR_FLAG)
623 return matches;
624
625 if (can_id & CAN_EFF_FLAG) {
626 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_eff[effhash(can_id)], list) {
627 if (rcv->can_id == can_id) {
628 deliver(skb, rcv);
629 matches++;
630 }
631 }
632 } else {
633 can_id &= CAN_SFF_MASK;
634 hlist_for_each_entry_rcu(rcv, &dev_rcv_lists->rx_sff[can_id], list) {
635 deliver(skb, rcv);
636 matches++;
637 }
638 }
639
640 return matches;
641}
642
643static void can_receive(struct sk_buff *skb, struct net_device *dev)
644{
645 struct can_dev_rcv_lists *dev_rcv_lists;
646 struct net *net = dev_net(dev);
647 struct can_pkg_stats *pkg_stats = net->can.pkg_stats;
648 int matches;
649
650 /* update statistics */
651 pkg_stats->rx_frames++;
652 pkg_stats->rx_frames_delta++;
653
654 /* create non-zero unique skb identifier together with *skb */
655 while (!(can_skb_prv(skb)->skbcnt))
656 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
657
658 rcu_read_lock();
659
660 /* deliver the packet to sockets listening on all devices */
661 matches = can_rcv_filter(net->can.rx_alldev_list, skb);
662
663 /* find receive list for this device */
664 dev_rcv_lists = can_dev_rcv_lists_find(net, dev);
665 matches += can_rcv_filter(dev_rcv_lists, skb);
666
667 rcu_read_unlock();
668
669 /* consume the skbuff allocated by the netdevice driver */
670 consume_skb(skb);
671
672 if (matches > 0) {
673 pkg_stats->matches++;
674 pkg_stats->matches_delta++;
675 }
676}
677
678static int can_rcv(struct sk_buff *skb, struct net_device *dev,
679 struct packet_type *pt, struct net_device *orig_dev)
680{
681 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
682
683 if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU)) {
684 pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d\n",
685 dev->type, skb->len);
686 goto free_skb;
687 }
688
689 /* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */
690 if (unlikely(cfd->len > CAN_MAX_DLEN)) {
691 pr_warn_once("PF_CAN: dropped non conform CAN skbuff: dev type %d, len %d, datalen %d\n",
692 dev->type, skb->len, cfd->len);
693 goto free_skb;
694 }
695
696 can_receive(skb, dev);
697 return NET_RX_SUCCESS;
698
699free_skb:
700 kfree_skb(skb);
701 return NET_RX_DROP;
702}
703
704static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
705 struct packet_type *pt, struct net_device *orig_dev)
706{
707 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
708
709 if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU)) {
710 pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d\n",
711 dev->type, skb->len);
712 goto free_skb;
713 }
714
715 /* This check is made separately since cfd->len would be uninitialized if skb->len = 0. */
716 if (unlikely(cfd->len > CANFD_MAX_DLEN)) {
717 pr_warn_once("PF_CAN: dropped non conform CAN FD skbuff: dev type %d, len %d, datalen %d\n",
718 dev->type, skb->len, cfd->len);
719 goto free_skb;
720 }
721
722 can_receive(skb, dev);
723 return NET_RX_SUCCESS;
724
725free_skb:
726 kfree_skb(skb);
727 return NET_RX_DROP;
728}
729
730/* af_can protocol functions */
731
732/**
733 * can_proto_register - register CAN transport protocol
734 * @cp: pointer to CAN protocol structure
735 *
736 * Return:
737 * 0 on success
738 * -EINVAL invalid (out of range) protocol number
739 * -EBUSY protocol already in use
740 * -ENOBUF if proto_register() fails
741 */
742int can_proto_register(const struct can_proto *cp)
743{
744 int proto = cp->protocol;
745 int err = 0;
746
747 if (proto < 0 || proto >= CAN_NPROTO) {
748 pr_err("can: protocol number %d out of range\n", proto);
749 return -EINVAL;
750 }
751
752 err = proto_register(cp->prot, 0);
753 if (err < 0)
754 return err;
755
756 mutex_lock(&proto_tab_lock);
757
758 if (rcu_access_pointer(proto_tab[proto])) {
759 pr_err("can: protocol %d already registered\n", proto);
760 err = -EBUSY;
761 } else {
762 RCU_INIT_POINTER(proto_tab[proto], cp);
763 }
764
765 mutex_unlock(&proto_tab_lock);
766
767 if (err < 0)
768 proto_unregister(cp->prot);
769
770 return err;
771}
772EXPORT_SYMBOL(can_proto_register);
773
774/**
775 * can_proto_unregister - unregister CAN transport protocol
776 * @cp: pointer to CAN protocol structure
777 */
778void can_proto_unregister(const struct can_proto *cp)
779{
780 int proto = cp->protocol;
781
782 mutex_lock(&proto_tab_lock);
783 BUG_ON(rcu_access_pointer(proto_tab[proto]) != cp);
784 RCU_INIT_POINTER(proto_tab[proto], NULL);
785 mutex_unlock(&proto_tab_lock);
786
787 synchronize_rcu();
788
789 proto_unregister(cp->prot);
790}
791EXPORT_SYMBOL(can_proto_unregister);
792
793static int can_pernet_init(struct net *net)
794{
795 spin_lock_init(&net->can.rcvlists_lock);
796 net->can.rx_alldev_list =
797 kzalloc(sizeof(*net->can.rx_alldev_list), GFP_KERNEL);
798 if (!net->can.rx_alldev_list)
799 goto out;
800 net->can.pkg_stats = kzalloc(sizeof(*net->can.pkg_stats), GFP_KERNEL);
801 if (!net->can.pkg_stats)
802 goto out_free_rx_alldev_list;
803 net->can.rcv_lists_stats = kzalloc(sizeof(*net->can.rcv_lists_stats), GFP_KERNEL);
804 if (!net->can.rcv_lists_stats)
805 goto out_free_pkg_stats;
806
807 if (IS_ENABLED(CONFIG_PROC_FS)) {
808 /* the statistics are updated every second (timer triggered) */
809 if (stats_timer) {
810 timer_setup(&net->can.stattimer, can_stat_update,
811 0);
812 mod_timer(&net->can.stattimer,
813 round_jiffies(jiffies + HZ));
814 }
815 net->can.pkg_stats->jiffies_init = jiffies;
816 can_init_proc(net);
817 }
818
819 return 0;
820
821 out_free_pkg_stats:
822 kfree(net->can.pkg_stats);
823 out_free_rx_alldev_list:
824 kfree(net->can.rx_alldev_list);
825 out:
826 return -ENOMEM;
827}
828
829static void can_pernet_exit(struct net *net)
830{
831 if (IS_ENABLED(CONFIG_PROC_FS)) {
832 can_remove_proc(net);
833 if (stats_timer)
834 del_timer_sync(&net->can.stattimer);
835 }
836
837 kfree(net->can.rx_alldev_list);
838 kfree(net->can.pkg_stats);
839 kfree(net->can.rcv_lists_stats);
840}
841
842/* af_can module init/exit functions */
843
844static struct packet_type can_packet __read_mostly = {
845 .type = cpu_to_be16(ETH_P_CAN),
846 .func = can_rcv,
847};
848
849static struct packet_type canfd_packet __read_mostly = {
850 .type = cpu_to_be16(ETH_P_CANFD),
851 .func = canfd_rcv,
852};
853
854static const struct net_proto_family can_family_ops = {
855 .family = PF_CAN,
856 .create = can_create,
857 .owner = THIS_MODULE,
858};
859
860static struct pernet_operations can_pernet_ops __read_mostly = {
861 .init = can_pernet_init,
862 .exit = can_pernet_exit,
863};
864
865static __init int can_init(void)
866{
867 int err;
868
869 /* check for correct padding to be able to use the structs similarly */
870 BUILD_BUG_ON(offsetof(struct can_frame, len) !=
871 offsetof(struct canfd_frame, len) ||
872 offsetof(struct can_frame, data) !=
873 offsetof(struct canfd_frame, data));
874
875 pr_info("can: controller area network core\n");
876
877 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
878 0, 0, NULL);
879 if (!rcv_cache)
880 return -ENOMEM;
881
882 err = register_pernet_subsys(&can_pernet_ops);
883 if (err)
884 goto out_pernet;
885
886 /* protocol register */
887 err = sock_register(&can_family_ops);
888 if (err)
889 goto out_sock;
890
891 dev_add_pack(&can_packet);
892 dev_add_pack(&canfd_packet);
893
894 return 0;
895
896out_sock:
897 unregister_pernet_subsys(&can_pernet_ops);
898out_pernet:
899 kmem_cache_destroy(rcv_cache);
900
901 return err;
902}
903
904static __exit void can_exit(void)
905{
906 /* protocol unregister */
907 dev_remove_pack(&canfd_packet);
908 dev_remove_pack(&can_packet);
909 sock_unregister(PF_CAN);
910
911 unregister_pernet_subsys(&can_pernet_ops);
912
913 rcu_barrier(); /* Wait for completion of call_rcu()'s */
914
915 kmem_cache_destroy(rcv_cache);
916}
917
918module_init(can_init);
919module_exit(can_exit);
1/*
2 * af_can.c - Protocol family CAN core module
3 * (used by different CAN protocol modules)
4 *
5 * Copyright (c) 2002-2017 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/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, 0444);
76MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
77
78static struct kmem_cache *rcv_cache __read_mostly;
79
80/* table of registered CAN protocols */
81static const struct can_proto __rcu *proto_tab[CAN_NPROTO] __read_mostly;
82static DEFINE_MUTEX(proto_tab_lock);
83
84static atomic_t skbcounter = ATOMIC_INIT(0);
85
86/*
87 * af_can socket functions
88 */
89
90int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
91{
92 struct sock *sk = sock->sk;
93
94 switch (cmd) {
95
96 case SIOCGSTAMP:
97 return sock_get_timestamp(sk, (struct timeval __user *)arg);
98
99 default:
100 return -ENOIOCTLCMD;
101 }
102}
103EXPORT_SYMBOL(can_ioctl);
104
105static void can_sock_destruct(struct sock *sk)
106{
107 skb_queue_purge(&sk->sk_receive_queue);
108}
109
110static const struct can_proto *can_get_proto(int protocol)
111{
112 const struct can_proto *cp;
113
114 rcu_read_lock();
115 cp = rcu_dereference(proto_tab[protocol]);
116 if (cp && !try_module_get(cp->prot->owner))
117 cp = NULL;
118 rcu_read_unlock();
119
120 return cp;
121}
122
123static inline void can_put_proto(const struct can_proto *cp)
124{
125 module_put(cp->prot->owner);
126}
127
128static int can_create(struct net *net, struct socket *sock, int protocol,
129 int kern)
130{
131 struct sock *sk;
132 const struct can_proto *cp;
133 int err = 0;
134
135 sock->state = SS_UNCONNECTED;
136
137 if (protocol < 0 || protocol >= CAN_NPROTO)
138 return -EINVAL;
139
140 cp = can_get_proto(protocol);
141
142#ifdef CONFIG_MODULES
143 if (!cp) {
144 /* try to load protocol module if kernel is modular */
145
146 err = request_module("can-proto-%d", protocol);
147
148 /*
149 * In case of error we only print a message but don't
150 * return the error code immediately. Below we will
151 * return -EPROTONOSUPPORT
152 */
153 if (err)
154 printk_ratelimited(KERN_ERR "can: request_module "
155 "(can-proto-%d) failed.\n", protocol);
156
157 cp = can_get_proto(protocol);
158 }
159#endif
160
161 /* check for available protocol and correct usage */
162
163 if (!cp)
164 return -EPROTONOSUPPORT;
165
166 if (cp->type != sock->type) {
167 err = -EPROTOTYPE;
168 goto errout;
169 }
170
171 sock->ops = cp->ops;
172
173 sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot, kern);
174 if (!sk) {
175 err = -ENOMEM;
176 goto errout;
177 }
178
179 sock_init_data(sock, sk);
180 sk->sk_destruct = can_sock_destruct;
181
182 if (sk->sk_prot->init)
183 err = sk->sk_prot->init(sk);
184
185 if (err) {
186 /* release sk on errors */
187 sock_orphan(sk);
188 sock_put(sk);
189 }
190
191 errout:
192 can_put_proto(cp);
193 return err;
194}
195
196/*
197 * af_can tx path
198 */
199
200/**
201 * can_send - transmit a CAN frame (optional with local loopback)
202 * @skb: pointer to socket buffer with CAN frame in data section
203 * @loop: loopback for listeners on local CAN sockets (recommended default!)
204 *
205 * Due to the loopback this routine must not be called from hardirq context.
206 *
207 * Return:
208 * 0 on success
209 * -ENETDOWN when the selected interface is down
210 * -ENOBUFS on full driver queue (see net_xmit_errno())
211 * -ENOMEM when local loopback failed at calling skb_clone()
212 * -EPERM when trying to send on a non-CAN interface
213 * -EMSGSIZE CAN frame size is bigger than CAN interface MTU
214 * -EINVAL when the skb->data does not contain a valid CAN frame
215 */
216int can_send(struct sk_buff *skb, int loop)
217{
218 struct sk_buff *newskb = NULL;
219 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
220 struct s_stats *can_stats = dev_net(skb->dev)->can.can_stats;
221 int err = -EINVAL;
222
223 if (skb->len == CAN_MTU) {
224 skb->protocol = htons(ETH_P_CAN);
225 if (unlikely(cfd->len > CAN_MAX_DLEN))
226 goto inval_skb;
227 } else if (skb->len == CANFD_MTU) {
228 skb->protocol = htons(ETH_P_CANFD);
229 if (unlikely(cfd->len > CANFD_MAX_DLEN))
230 goto inval_skb;
231 } else
232 goto inval_skb;
233
234 /*
235 * Make sure the CAN frame can pass the selected CAN netdevice.
236 * As structs can_frame and canfd_frame are similar, we can provide
237 * CAN FD frames to legacy CAN drivers as long as the length is <= 8
238 */
239 if (unlikely(skb->len > skb->dev->mtu && cfd->len > CAN_MAX_DLEN)) {
240 err = -EMSGSIZE;
241 goto inval_skb;
242 }
243
244 if (unlikely(skb->dev->type != ARPHRD_CAN)) {
245 err = -EPERM;
246 goto inval_skb;
247 }
248
249 if (unlikely(!(skb->dev->flags & IFF_UP))) {
250 err = -ENETDOWN;
251 goto inval_skb;
252 }
253
254 skb->ip_summed = CHECKSUM_UNNECESSARY;
255
256 skb_reset_mac_header(skb);
257 skb_reset_network_header(skb);
258 skb_reset_transport_header(skb);
259
260 if (loop) {
261 /* local loopback of sent CAN frames */
262
263 /* indication for the CAN driver: do loopback */
264 skb->pkt_type = PACKET_LOOPBACK;
265
266 /*
267 * The reference to the originating sock may be required
268 * by the receiving socket to check whether the frame is
269 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
270 * Therefore we have to ensure that skb->sk remains the
271 * reference to the originating sock by restoring skb->sk
272 * after each skb_clone() or skb_orphan() usage.
273 */
274
275 if (!(skb->dev->flags & IFF_ECHO)) {
276 /*
277 * If the interface is not capable to do loopback
278 * itself, we do it here.
279 */
280 newskb = skb_clone(skb, GFP_ATOMIC);
281 if (!newskb) {
282 kfree_skb(skb);
283 return -ENOMEM;
284 }
285
286 can_skb_set_owner(newskb, skb->sk);
287 newskb->ip_summed = CHECKSUM_UNNECESSARY;
288 newskb->pkt_type = PACKET_BROADCAST;
289 }
290 } else {
291 /* indication for the CAN driver: no loopback required */
292 skb->pkt_type = PACKET_HOST;
293 }
294
295 /* send to netdevice */
296 err = dev_queue_xmit(skb);
297 if (err > 0)
298 err = net_xmit_errno(err);
299
300 if (err) {
301 kfree_skb(newskb);
302 return err;
303 }
304
305 if (newskb)
306 netif_rx_ni(newskb);
307
308 /* update statistics */
309 can_stats->tx_frames++;
310 can_stats->tx_frames_delta++;
311
312 return 0;
313
314inval_skb:
315 kfree_skb(skb);
316 return err;
317}
318EXPORT_SYMBOL(can_send);
319
320/*
321 * af_can rx path
322 */
323
324static struct can_dev_rcv_lists *find_dev_rcv_lists(struct net *net,
325 struct net_device *dev)
326{
327 if (!dev)
328 return net->can.can_rx_alldev_list;
329 else
330 return (struct can_dev_rcv_lists *)dev->ml_priv;
331}
332
333/**
334 * effhash - hash function for 29 bit CAN identifier reduction
335 * @can_id: 29 bit CAN identifier
336 *
337 * Description:
338 * To reduce the linear traversal in one linked list of _single_ EFF CAN
339 * frame subscriptions the 29 bit identifier is mapped to 10 bits.
340 * (see CAN_EFF_RCV_HASH_BITS definition)
341 *
342 * Return:
343 * Hash value from 0x000 - 0x3FF ( enforced by CAN_EFF_RCV_HASH_BITS mask )
344 */
345static unsigned int effhash(canid_t can_id)
346{
347 unsigned int hash;
348
349 hash = can_id;
350 hash ^= can_id >> CAN_EFF_RCV_HASH_BITS;
351 hash ^= can_id >> (2 * CAN_EFF_RCV_HASH_BITS);
352
353 return hash & ((1 << CAN_EFF_RCV_HASH_BITS) - 1);
354}
355
356/**
357 * find_rcv_list - determine optimal filterlist inside device filter struct
358 * @can_id: pointer to CAN identifier of a given can_filter
359 * @mask: pointer to CAN mask of a given can_filter
360 * @d: pointer to the device filter struct
361 *
362 * Description:
363 * Returns the optimal filterlist to reduce the filter handling in the
364 * receive path. This function is called by service functions that need
365 * to register or unregister a can_filter in the filter lists.
366 *
367 * A filter matches in general, when
368 *
369 * <received_can_id> & mask == can_id & mask
370 *
371 * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
372 * relevant bits for the filter.
373 *
374 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
375 * filter for error messages (CAN_ERR_FLAG bit set in mask). For error msg
376 * frames there is a special filterlist and a special rx path filter handling.
377 *
378 * Return:
379 * Pointer to optimal filterlist for the given can_id/mask pair.
380 * Constistency checked mask.
381 * Reduced can_id to have a preprocessed filter compare value.
382 */
383static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
384 struct can_dev_rcv_lists *d)
385{
386 canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
387
388 /* filter for error message frames in extra filterlist */
389 if (*mask & CAN_ERR_FLAG) {
390 /* clear CAN_ERR_FLAG in filter entry */
391 *mask &= CAN_ERR_MASK;
392 return &d->rx[RX_ERR];
393 }
394
395 /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
396
397#define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
398
399 /* ensure valid values in can_mask for 'SFF only' frame filtering */
400 if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
401 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
402
403 /* reduce condition testing at receive time */
404 *can_id &= *mask;
405
406 /* inverse can_id/can_mask filter */
407 if (inv)
408 return &d->rx[RX_INV];
409
410 /* mask == 0 => no condition testing at receive time */
411 if (!(*mask))
412 return &d->rx[RX_ALL];
413
414 /* extra filterlists for the subscription of a single non-RTR can_id */
415 if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
416 !(*can_id & CAN_RTR_FLAG)) {
417
418 if (*can_id & CAN_EFF_FLAG) {
419 if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
420 return &d->rx_eff[effhash(*can_id)];
421 } else {
422 if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
423 return &d->rx_sff[*can_id];
424 }
425 }
426
427 /* default: filter via can_id/can_mask */
428 return &d->rx[RX_FIL];
429}
430
431/**
432 * can_rx_register - subscribe CAN frames from a specific interface
433 * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
434 * @can_id: CAN identifier (see description)
435 * @mask: CAN mask (see description)
436 * @func: callback function on filter match
437 * @data: returned parameter for callback function
438 * @ident: string for calling module identification
439 * @sk: socket pointer (might be NULL)
440 *
441 * Description:
442 * Invokes the callback function with the received sk_buff and the given
443 * parameter 'data' on a matching receive filter. A filter matches, when
444 *
445 * <received_can_id> & mask == can_id & mask
446 *
447 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
448 * filter for error message frames (CAN_ERR_FLAG bit set in mask).
449 *
450 * The provided pointer to the sk_buff is guaranteed to be valid as long as
451 * the callback function is running. The callback function must *not* free
452 * the given sk_buff while processing it's task. When the given sk_buff is
453 * needed after the end of the callback function it must be cloned inside
454 * the callback function with skb_clone().
455 *
456 * Return:
457 * 0 on success
458 * -ENOMEM on missing cache mem to create subscription entry
459 * -ENODEV unknown device
460 */
461int can_rx_register(struct net *net, struct net_device *dev, canid_t can_id,
462 canid_t mask, void (*func)(struct sk_buff *, void *),
463 void *data, char *ident, struct sock *sk)
464{
465 struct receiver *r;
466 struct hlist_head *rl;
467 struct can_dev_rcv_lists *d;
468 struct s_pstats *can_pstats = net->can.can_pstats;
469 int err = 0;
470
471 /* insert new receiver (dev,canid,mask) -> (func,data) */
472
473 if (dev && dev->type != ARPHRD_CAN)
474 return -ENODEV;
475
476 if (dev && !net_eq(net, dev_net(dev)))
477 return -ENODEV;
478
479 r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
480 if (!r)
481 return -ENOMEM;
482
483 spin_lock(&net->can.can_rcvlists_lock);
484
485 d = find_dev_rcv_lists(net, dev);
486 if (d) {
487 rl = find_rcv_list(&can_id, &mask, d);
488
489 r->can_id = can_id;
490 r->mask = mask;
491 r->matches = 0;
492 r->func = func;
493 r->data = data;
494 r->ident = ident;
495 r->sk = sk;
496
497 hlist_add_head_rcu(&r->list, rl);
498 d->entries++;
499
500 can_pstats->rcv_entries++;
501 if (can_pstats->rcv_entries_max < can_pstats->rcv_entries)
502 can_pstats->rcv_entries_max = can_pstats->rcv_entries;
503 } else {
504 kmem_cache_free(rcv_cache, r);
505 err = -ENODEV;
506 }
507
508 spin_unlock(&net->can.can_rcvlists_lock);
509
510 return err;
511}
512EXPORT_SYMBOL(can_rx_register);
513
514/*
515 * can_rx_delete_receiver - rcu callback for single receiver entry removal
516 */
517static void can_rx_delete_receiver(struct rcu_head *rp)
518{
519 struct receiver *r = container_of(rp, struct receiver, rcu);
520 struct sock *sk = r->sk;
521
522 kmem_cache_free(rcv_cache, r);
523 if (sk)
524 sock_put(sk);
525}
526
527/**
528 * can_rx_unregister - unsubscribe CAN frames from a specific interface
529 * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
530 * @can_id: CAN identifier
531 * @mask: CAN mask
532 * @func: callback function on filter match
533 * @data: returned parameter for callback function
534 *
535 * Description:
536 * Removes subscription entry depending on given (subscription) values.
537 */
538void can_rx_unregister(struct net *net, struct net_device *dev, canid_t can_id,
539 canid_t mask, void (*func)(struct sk_buff *, void *),
540 void *data)
541{
542 struct receiver *r = NULL;
543 struct hlist_head *rl;
544 struct s_pstats *can_pstats = net->can.can_pstats;
545 struct can_dev_rcv_lists *d;
546
547 if (dev && dev->type != ARPHRD_CAN)
548 return;
549
550 if (dev && !net_eq(net, dev_net(dev)))
551 return;
552
553 spin_lock(&net->can.can_rcvlists_lock);
554
555 d = find_dev_rcv_lists(net, 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(&net->can.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 can_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 can_dev_rcv_lists *d;
686 struct net *net = dev_net(dev);
687 struct s_stats *can_stats = net->can.can_stats;
688 int matches;
689
690 /* update statistics */
691 can_stats->rx_frames++;
692 can_stats->rx_frames_delta++;
693
694 /* create non-zero unique skb identifier together with *skb */
695 while (!(can_skb_prv(skb)->skbcnt))
696 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
697
698 rcu_read_lock();
699
700 /* deliver the packet to sockets listening on all devices */
701 matches = can_rcv_filter(net->can.can_rx_alldev_list, skb);
702
703 /* find receive list for this device */
704 d = find_dev_rcv_lists(net, dev);
705 if (d)
706 matches += can_rcv_filter(d, skb);
707
708 rcu_read_unlock();
709
710 /* consume the skbuff allocated by the netdevice driver */
711 consume_skb(skb);
712
713 if (matches > 0) {
714 can_stats->matches++;
715 can_stats->matches_delta++;
716 }
717}
718
719static int can_rcv(struct sk_buff *skb, struct net_device *dev,
720 struct packet_type *pt, struct net_device *orig_dev)
721{
722 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
723
724 if (unlikely(dev->type != ARPHRD_CAN || skb->len != CAN_MTU ||
725 cfd->len > CAN_MAX_DLEN)) {
726 pr_warn_once("PF_CAN: dropped non conform CAN skbuf: dev type %d, len %d, datalen %d\n",
727 dev->type, skb->len, cfd->len);
728 kfree_skb(skb);
729 return NET_RX_DROP;
730 }
731
732 can_receive(skb, dev);
733 return NET_RX_SUCCESS;
734}
735
736static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
737 struct packet_type *pt, struct net_device *orig_dev)
738{
739 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
740
741 if (unlikely(dev->type != ARPHRD_CAN || skb->len != CANFD_MTU ||
742 cfd->len > CANFD_MAX_DLEN)) {
743 pr_warn_once("PF_CAN: dropped non conform CAN FD skbuf: dev type %d, len %d, datalen %d\n",
744 dev->type, skb->len, cfd->len);
745 kfree_skb(skb);
746 return NET_RX_DROP;
747 }
748
749 can_receive(skb, dev);
750 return NET_RX_SUCCESS;
751}
752
753/*
754 * af_can protocol functions
755 */
756
757/**
758 * can_proto_register - register CAN transport protocol
759 * @cp: pointer to CAN protocol structure
760 *
761 * Return:
762 * 0 on success
763 * -EINVAL invalid (out of range) protocol number
764 * -EBUSY protocol already in use
765 * -ENOBUF if proto_register() fails
766 */
767int can_proto_register(const struct can_proto *cp)
768{
769 int proto = cp->protocol;
770 int err = 0;
771
772 if (proto < 0 || proto >= CAN_NPROTO) {
773 pr_err("can: protocol number %d out of range\n", proto);
774 return -EINVAL;
775 }
776
777 err = proto_register(cp->prot, 0);
778 if (err < 0)
779 return err;
780
781 mutex_lock(&proto_tab_lock);
782
783 if (rcu_access_pointer(proto_tab[proto])) {
784 pr_err("can: protocol %d already registered\n", proto);
785 err = -EBUSY;
786 } else
787 RCU_INIT_POINTER(proto_tab[proto], cp);
788
789 mutex_unlock(&proto_tab_lock);
790
791 if (err < 0)
792 proto_unregister(cp->prot);
793
794 return err;
795}
796EXPORT_SYMBOL(can_proto_register);
797
798/**
799 * can_proto_unregister - unregister CAN transport protocol
800 * @cp: pointer to CAN protocol structure
801 */
802void can_proto_unregister(const struct can_proto *cp)
803{
804 int proto = cp->protocol;
805
806 mutex_lock(&proto_tab_lock);
807 BUG_ON(rcu_access_pointer(proto_tab[proto]) != cp);
808 RCU_INIT_POINTER(proto_tab[proto], NULL);
809 mutex_unlock(&proto_tab_lock);
810
811 synchronize_rcu();
812
813 proto_unregister(cp->prot);
814}
815EXPORT_SYMBOL(can_proto_unregister);
816
817/*
818 * af_can notifier to create/remove CAN netdevice specific structs
819 */
820static int can_notifier(struct notifier_block *nb, unsigned long msg,
821 void *ptr)
822{
823 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
824 struct can_dev_rcv_lists *d;
825
826 if (dev->type != ARPHRD_CAN)
827 return NOTIFY_DONE;
828
829 switch (msg) {
830
831 case NETDEV_REGISTER:
832
833 /* create new dev_rcv_lists for this device */
834 d = kzalloc(sizeof(*d), GFP_KERNEL);
835 if (!d)
836 return NOTIFY_DONE;
837 BUG_ON(dev->ml_priv);
838 dev->ml_priv = d;
839
840 break;
841
842 case NETDEV_UNREGISTER:
843 spin_lock(&dev_net(dev)->can.can_rcvlists_lock);
844
845 d = dev->ml_priv;
846 if (d) {
847 if (d->entries)
848 d->remove_on_zero_entries = 1;
849 else {
850 kfree(d);
851 dev->ml_priv = NULL;
852 }
853 } else
854 pr_err("can: notifier: receive list not found for dev "
855 "%s\n", dev->name);
856
857 spin_unlock(&dev_net(dev)->can.can_rcvlists_lock);
858
859 break;
860 }
861
862 return NOTIFY_DONE;
863}
864
865static int can_pernet_init(struct net *net)
866{
867 spin_lock_init(&net->can.can_rcvlists_lock);
868 net->can.can_rx_alldev_list =
869 kzalloc(sizeof(struct can_dev_rcv_lists), GFP_KERNEL);
870 if (!net->can.can_rx_alldev_list)
871 goto out;
872 net->can.can_stats = kzalloc(sizeof(struct s_stats), GFP_KERNEL);
873 if (!net->can.can_stats)
874 goto out_free_alldev_list;
875 net->can.can_pstats = kzalloc(sizeof(struct s_pstats), GFP_KERNEL);
876 if (!net->can.can_pstats)
877 goto out_free_can_stats;
878
879 if (IS_ENABLED(CONFIG_PROC_FS)) {
880 /* the statistics are updated every second (timer triggered) */
881 if (stats_timer) {
882 timer_setup(&net->can.can_stattimer, can_stat_update,
883 0);
884 mod_timer(&net->can.can_stattimer,
885 round_jiffies(jiffies + HZ));
886 }
887 net->can.can_stats->jiffies_init = jiffies;
888 can_init_proc(net);
889 }
890
891 return 0;
892
893 out_free_can_stats:
894 kfree(net->can.can_stats);
895 out_free_alldev_list:
896 kfree(net->can.can_rx_alldev_list);
897 out:
898 return -ENOMEM;
899}
900
901static void can_pernet_exit(struct net *net)
902{
903 struct net_device *dev;
904
905 if (IS_ENABLED(CONFIG_PROC_FS)) {
906 can_remove_proc(net);
907 if (stats_timer)
908 del_timer_sync(&net->can.can_stattimer);
909 }
910
911 /* remove created dev_rcv_lists from still registered CAN devices */
912 rcu_read_lock();
913 for_each_netdev_rcu(net, dev) {
914 if (dev->type == ARPHRD_CAN && dev->ml_priv) {
915 struct can_dev_rcv_lists *d = dev->ml_priv;
916
917 BUG_ON(d->entries);
918 kfree(d);
919 dev->ml_priv = NULL;
920 }
921 }
922 rcu_read_unlock();
923
924 kfree(net->can.can_rx_alldev_list);
925 kfree(net->can.can_stats);
926 kfree(net->can.can_pstats);
927}
928
929/*
930 * af_can module init/exit functions
931 */
932
933static struct packet_type can_packet __read_mostly = {
934 .type = cpu_to_be16(ETH_P_CAN),
935 .func = can_rcv,
936};
937
938static struct packet_type canfd_packet __read_mostly = {
939 .type = cpu_to_be16(ETH_P_CANFD),
940 .func = canfd_rcv,
941};
942
943static const struct net_proto_family can_family_ops = {
944 .family = PF_CAN,
945 .create = can_create,
946 .owner = THIS_MODULE,
947};
948
949/* notifier block for netdevice event */
950static struct notifier_block can_netdev_notifier __read_mostly = {
951 .notifier_call = can_notifier,
952};
953
954static struct pernet_operations can_pernet_ops __read_mostly = {
955 .init = can_pernet_init,
956 .exit = can_pernet_exit,
957};
958
959static __init int can_init(void)
960{
961 /* check for correct padding to be able to use the structs similarly */
962 BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
963 offsetof(struct canfd_frame, len) ||
964 offsetof(struct can_frame, data) !=
965 offsetof(struct canfd_frame, data));
966
967 pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
968
969 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
970 0, 0, NULL);
971 if (!rcv_cache)
972 return -ENOMEM;
973
974 register_pernet_subsys(&can_pernet_ops);
975
976 /* protocol register */
977 sock_register(&can_family_ops);
978 register_netdevice_notifier(&can_netdev_notifier);
979 dev_add_pack(&can_packet);
980 dev_add_pack(&canfd_packet);
981
982 return 0;
983}
984
985static __exit void can_exit(void)
986{
987 /* protocol unregister */
988 dev_remove_pack(&canfd_packet);
989 dev_remove_pack(&can_packet);
990 unregister_netdevice_notifier(&can_netdev_notifier);
991 sock_unregister(PF_CAN);
992
993 unregister_pernet_subsys(&can_pernet_ops);
994
995 rcu_barrier(); /* Wait for completion of call_rcu()'s */
996
997 kmem_cache_destroy(rcv_cache);
998}
999
1000module_init(can_init);
1001module_exit(can_exit);