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Linux/net/can/af_can.c

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  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 
 67 MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
 68 MODULE_LICENSE("Dual BSD/GPL");
 69 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
 70               "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
 71 
 72 MODULE_ALIAS_NETPROTO(PF_CAN);
 73 
 74 static int stats_timer __read_mostly = 1;
 75 module_param(stats_timer, int, S_IRUGO);
 76 MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
 77 
 78 /* receive filters subscribed for 'all' CAN devices */
 79 struct dev_rcv_lists can_rx_alldev_list;
 80 static DEFINE_SPINLOCK(can_rcvlists_lock);
 81 
 82 static struct kmem_cache *rcv_cache __read_mostly;
 83 
 84 /* table of registered CAN protocols */
 85 static const struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
 86 static DEFINE_MUTEX(proto_tab_lock);
 87 
 88 struct timer_list can_stattimer;   /* timer for statistics update */
 89 struct s_stats    can_stats;       /* packet statistics */
 90 struct s_pstats   can_pstats;      /* receive list statistics */
 91 
 92 static atomic_t skbcounter = ATOMIC_INIT(0);
 93 
 94 /*
 95  * af_can socket functions
 96  */
 97 
 98 int 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 }
111 EXPORT_SYMBOL(can_ioctl);
112 
113 static void can_sock_destruct(struct sock *sk)
114 {
115         skb_queue_purge(&sk->sk_receive_queue);
116 }
117 
118 static 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 
131 static inline void can_put_proto(const struct can_proto *cp)
132 {
133         module_put(cp->prot->owner);
134 }
135 
136 static 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  */
227 int 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 
324 inval_skb:
325         kfree_skb(skb);
326         return err;
327 }
328 EXPORT_SYMBOL(can_send);
329 
330 /*
331  * af_can rx path
332  */
333 
334 static 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  */
354 static 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  */
392 static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
393                                         struct dev_rcv_lists *d)
394 {
395         canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
396 
397         /* filter for error message frames in extra filterlist */
398         if (*mask & CAN_ERR_FLAG) {
399                 /* clear CAN_ERR_FLAG in filter entry */
400                 *mask &= CAN_ERR_MASK;
401                 return &d->rx[RX_ERR];
402         }
403 
404         /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
405 
406 #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
407 
408         /* ensure valid values in can_mask for 'SFF only' frame filtering */
409         if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
410                 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
411 
412         /* reduce condition testing at receive time */
413         *can_id &= *mask;
414 
415         /* inverse can_id/can_mask filter */
416         if (inv)
417                 return &d->rx[RX_INV];
418 
419         /* mask == 0 => no condition testing at receive time */
420         if (!(*mask))
421                 return &d->rx[RX_ALL];
422 
423         /* extra filterlists for the subscription of a single non-RTR can_id */
424         if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS) &&
425             !(*can_id & CAN_RTR_FLAG)) {
426 
427                 if (*can_id & CAN_EFF_FLAG) {
428                         if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS))
429                                 return &d->rx_eff[effhash(*can_id)];
430                 } else {
431                         if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
432                                 return &d->rx_sff[*can_id];
433                 }
434         }
435 
436         /* default: filter via can_id/can_mask */
437         return &d->rx[RX_FIL];
438 }
439 
440 /**
441  * can_rx_register - subscribe CAN frames from a specific interface
442  * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
443  * @can_id: CAN identifier (see description)
444  * @mask: CAN mask (see description)
445  * @func: callback function on filter match
446  * @data: returned parameter for callback function
447  * @ident: string for calling module identification
448  *
449  * Description:
450  *  Invokes the callback function with the received sk_buff and the given
451  *  parameter 'data' on a matching receive filter. A filter matches, when
452  *
453  *          <received_can_id> & mask == can_id & mask
454  *
455  *  The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
456  *  filter for error message frames (CAN_ERR_FLAG bit set in mask).
457  *
458  *  The provided pointer to the sk_buff is guaranteed to be valid as long as
459  *  the callback function is running. The callback function must *not* free
460  *  the given sk_buff while processing it's task. When the given sk_buff is
461  *  needed after the end of the callback function it must be cloned inside
462  *  the callback function with skb_clone().
463  *
464  * Return:
465  *  0 on success
466  *  -ENOMEM on missing cache mem to create subscription entry
467  *  -ENODEV unknown device
468  */
469 int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
470                     void (*func)(struct sk_buff *, void *), void *data,
471                     char *ident)
472 {
473         struct receiver *r;
474         struct hlist_head *rl;
475         struct dev_rcv_lists *d;
476         int err = 0;
477 
478         /* insert new receiver  (dev,canid,mask) -> (func,data) */
479 
480         if (dev && dev->type != ARPHRD_CAN)
481                 return -ENODEV;
482 
483         r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
484         if (!r)
485                 return -ENOMEM;
486 
487         spin_lock(&can_rcvlists_lock);
488 
489         d = find_dev_rcv_lists(dev);
490         if (d) {
491                 rl = find_rcv_list(&can_id, &mask, d);
492 
493                 r->can_id  = can_id;
494                 r->mask    = mask;
495                 r->matches = 0;
496                 r->func    = func;
497                 r->data    = data;
498                 r->ident   = ident;
499 
500                 hlist_add_head_rcu(&r->list, rl);
501                 d->entries++;
502 
503                 can_pstats.rcv_entries++;
504                 if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
505                         can_pstats.rcv_entries_max = can_pstats.rcv_entries;
506         } else {
507                 kmem_cache_free(rcv_cache, r);
508                 err = -ENODEV;
509         }
510 
511         spin_unlock(&can_rcvlists_lock);
512 
513         return err;
514 }
515 EXPORT_SYMBOL(can_rx_register);
516 
517 /*
518  * can_rx_delete_receiver - rcu callback for single receiver entry removal
519  */
520 static void can_rx_delete_receiver(struct rcu_head *rp)
521 {
522         struct receiver *r = container_of(rp, struct receiver, rcu);
523 
524         kmem_cache_free(rcv_cache, r);
525 }
526 
527 /**
528  * can_rx_unregister - unsubscribe CAN frames from a specific interface
529  * @dev: pointer to netdevice (NULL => unsubscribe from 'all' CAN devices list)
530  * @can_id: CAN identifier
531  * @mask: CAN mask
532  * @func: callback function on filter match
533  * @data: returned parameter for callback function
534  *
535  * Description:
536  *  Removes subscription entry depending on given (subscription) values.
537  */
538 void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
539                        void (*func)(struct sk_buff *, void *), void *data)
540 {
541         struct receiver *r = NULL;
542         struct hlist_head *rl;
543         struct dev_rcv_lists *d;
544 
545         if (dev && dev->type != ARPHRD_CAN)
546                 return;
547 
548         spin_lock(&can_rcvlists_lock);
549 
550         d = find_dev_rcv_lists(dev);
551         if (!d) {
552                 pr_err("BUG: receive list not found for "
553                        "dev %s, id %03X, mask %03X\n",
554                        DNAME(dev), can_id, mask);
555                 goto out;
556         }
557 
558         rl = find_rcv_list(&can_id, &mask, d);
559 
560         /*
561          * Search the receiver list for the item to delete.  This should
562          * exist, since no receiver may be unregistered that hasn't
563          * been registered before.
564          */
565 
566         hlist_for_each_entry_rcu(r, rl, list) {
567                 if (r->can_id == can_id && r->mask == mask &&
568                     r->func == func && r->data == data)
569                         break;
570         }
571 
572         /*
573          * Check for bugs in CAN protocol implementations using af_can.c:
574          * 'r' will be NULL if no matching list item was found for removal.
575          */
576 
577         if (!r) {
578                 WARN(1, "BUG: receive list entry not found for dev %s, "
579                      "id %03X, mask %03X\n", DNAME(dev), can_id, mask);
580                 goto out;
581         }
582 
583         hlist_del_rcu(&r->list);
584         d->entries--;
585 
586         if (can_pstats.rcv_entries > 0)
587                 can_pstats.rcv_entries--;
588 
589         /* remove device structure requested by NETDEV_UNREGISTER */
590         if (d->remove_on_zero_entries && !d->entries) {
591                 kfree(d);
592                 dev->ml_priv = NULL;
593         }
594 
595  out:
596         spin_unlock(&can_rcvlists_lock);
597 
598         /* schedule the receiver item for deletion */
599         if (r)
600                 call_rcu(&r->rcu, can_rx_delete_receiver);
601 }
602 EXPORT_SYMBOL(can_rx_unregister);
603 
604 static inline void deliver(struct sk_buff *skb, struct receiver *r)
605 {
606         r->func(skb, r->data);
607         r->matches++;
608 }
609 
610 static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
611 {
612         struct receiver *r;
613         int matches = 0;
614         struct can_frame *cf = (struct can_frame *)skb->data;
615         canid_t can_id = cf->can_id;
616 
617         if (d->entries == 0)
618                 return 0;
619 
620         if (can_id & CAN_ERR_FLAG) {
621                 /* check for error message frame entries only */
622                 hlist_for_each_entry_rcu(r, &d->rx[RX_ERR], list) {
623                         if (can_id & r->mask) {
624                                 deliver(skb, r);
625                                 matches++;
626                         }
627                 }
628                 return matches;
629         }
630 
631         /* check for unfiltered entries */
632         hlist_for_each_entry_rcu(r, &d->rx[RX_ALL], list) {
633                 deliver(skb, r);
634                 matches++;
635         }
636 
637         /* check for can_id/mask entries */
638         hlist_for_each_entry_rcu(r, &d->rx[RX_FIL], list) {
639                 if ((can_id & r->mask) == r->can_id) {
640                         deliver(skb, r);
641                         matches++;
642                 }
643         }
644 
645         /* check for inverted can_id/mask entries */
646         hlist_for_each_entry_rcu(r, &d->rx[RX_INV], list) {
647                 if ((can_id & r->mask) != r->can_id) {
648                         deliver(skb, r);
649                         matches++;
650                 }
651         }
652 
653         /* check filterlists for single non-RTR can_ids */
654         if (can_id & CAN_RTR_FLAG)
655                 return matches;
656 
657         if (can_id & CAN_EFF_FLAG) {
658                 hlist_for_each_entry_rcu(r, &d->rx_eff[effhash(can_id)], list) {
659                         if (r->can_id == can_id) {
660                                 deliver(skb, r);
661                                 matches++;
662                         }
663                 }
664         } else {
665                 can_id &= CAN_SFF_MASK;
666                 hlist_for_each_entry_rcu(r, &d->rx_sff[can_id], list) {
667                         deliver(skb, r);
668                         matches++;
669                 }
670         }
671 
672         return matches;
673 }
674 
675 static void can_receive(struct sk_buff *skb, struct net_device *dev)
676 {
677         struct dev_rcv_lists *d;
678         int matches;
679 
680         /* update statistics */
681         can_stats.rx_frames++;
682         can_stats.rx_frames_delta++;
683 
684         /* create non-zero unique skb identifier together with *skb */
685         while (!(can_skb_prv(skb)->skbcnt))
686                 can_skb_prv(skb)->skbcnt = atomic_inc_return(&skbcounter);
687 
688         rcu_read_lock();
689 
690         /* deliver the packet to sockets listening on all devices */
691         matches = can_rcv_filter(&can_rx_alldev_list, skb);
692 
693         /* find receive list for this device */
694         d = find_dev_rcv_lists(dev);
695         if (d)
696                 matches += can_rcv_filter(d, skb);
697 
698         rcu_read_unlock();
699 
700         /* consume the skbuff allocated by the netdevice driver */
701         consume_skb(skb);
702 
703         if (matches > 0) {
704                 can_stats.matches++;
705                 can_stats.matches_delta++;
706         }
707 }
708 
709 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
710                    struct packet_type *pt, struct net_device *orig_dev)
711 {
712         struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
713 
714         if (unlikely(!net_eq(dev_net(dev), &init_net)))
715                 goto drop;
716 
717         if (WARN_ONCE(dev->type != ARPHRD_CAN ||
718                       skb->len != CAN_MTU ||
719                       cfd->len > CAN_MAX_DLEN,
720                       "PF_CAN: dropped non conform CAN skbuf: "
721                       "dev type %d, len %d, datalen %d\n",
722                       dev->type, skb->len, cfd->len))
723                 goto drop;
724 
725         can_receive(skb, dev);
726         return NET_RX_SUCCESS;
727 
728 drop:
729         kfree_skb(skb);
730         return NET_RX_DROP;
731 }
732 
733 static int canfd_rcv(struct sk_buff *skb, struct net_device *dev,
734                    struct packet_type *pt, struct net_device *orig_dev)
735 {
736         struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
737 
738         if (unlikely(!net_eq(dev_net(dev), &init_net)))
739                 goto drop;
740 
741         if (WARN_ONCE(dev->type != ARPHRD_CAN ||
742                       skb->len != CANFD_MTU ||
743                       cfd->len > CANFD_MAX_DLEN,
744                       "PF_CAN: dropped non conform CAN FD skbuf: "
745                       "dev type %d, len %d, datalen %d\n",
746                       dev->type, skb->len, cfd->len))
747                 goto drop;
748 
749         can_receive(skb, dev);
750         return NET_RX_SUCCESS;
751 
752 drop:
753         kfree_skb(skb);
754         return NET_RX_DROP;
755 }
756 
757 /*
758  * af_can protocol functions
759  */
760 
761 /**
762  * can_proto_register - register CAN transport protocol
763  * @cp: pointer to CAN protocol structure
764  *
765  * Return:
766  *  0 on success
767  *  -EINVAL invalid (out of range) protocol number
768  *  -EBUSY  protocol already in use
769  *  -ENOBUF if proto_register() fails
770  */
771 int can_proto_register(const struct can_proto *cp)
772 {
773         int proto = cp->protocol;
774         int err = 0;
775 
776         if (proto < 0 || proto >= CAN_NPROTO) {
777                 pr_err("can: protocol number %d out of range\n", proto);
778                 return -EINVAL;
779         }
780 
781         err = proto_register(cp->prot, 0);
782         if (err < 0)
783                 return err;
784 
785         mutex_lock(&proto_tab_lock);
786 
787         if (proto_tab[proto]) {
788                 pr_err("can: protocol %d already registered\n", proto);
789                 err = -EBUSY;
790         } else
791                 RCU_INIT_POINTER(proto_tab[proto], cp);
792 
793         mutex_unlock(&proto_tab_lock);
794 
795         if (err < 0)
796                 proto_unregister(cp->prot);
797 
798         return err;
799 }
800 EXPORT_SYMBOL(can_proto_register);
801 
802 /**
803  * can_proto_unregister - unregister CAN transport protocol
804  * @cp: pointer to CAN protocol structure
805  */
806 void can_proto_unregister(const struct can_proto *cp)
807 {
808         int proto = cp->protocol;
809 
810         mutex_lock(&proto_tab_lock);
811         BUG_ON(proto_tab[proto] != cp);
812         RCU_INIT_POINTER(proto_tab[proto], NULL);
813         mutex_unlock(&proto_tab_lock);
814 
815         synchronize_rcu();
816 
817         proto_unregister(cp->prot);
818 }
819 EXPORT_SYMBOL(can_proto_unregister);
820 
821 /*
822  * af_can notifier to create/remove CAN netdevice specific structs
823  */
824 static int can_notifier(struct notifier_block *nb, unsigned long msg,
825                         void *ptr)
826 {
827         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
828         struct dev_rcv_lists *d;
829 
830         if (!net_eq(dev_net(dev), &init_net))
831                 return NOTIFY_DONE;
832 
833         if (dev->type != ARPHRD_CAN)
834                 return NOTIFY_DONE;
835 
836         switch (msg) {
837 
838         case NETDEV_REGISTER:
839 
840                 /* create new dev_rcv_lists for this device */
841                 d = kzalloc(sizeof(*d), GFP_KERNEL);
842                 if (!d)
843                         return NOTIFY_DONE;
844                 BUG_ON(dev->ml_priv);
845                 dev->ml_priv = d;
846 
847                 break;
848 
849         case NETDEV_UNREGISTER:
850                 spin_lock(&can_rcvlists_lock);
851 
852                 d = dev->ml_priv;
853                 if (d) {
854                         if (d->entries)
855                                 d->remove_on_zero_entries = 1;
856                         else {
857                                 kfree(d);
858                                 dev->ml_priv = NULL;
859                         }
860                 } else
861                         pr_err("can: notifier: receive list not found for dev "
862                                "%s\n", dev->name);
863 
864                 spin_unlock(&can_rcvlists_lock);
865 
866                 break;
867         }
868 
869         return NOTIFY_DONE;
870 }
871 
872 /*
873  * af_can module init/exit functions
874  */
875 
876 static struct packet_type can_packet __read_mostly = {
877         .type = cpu_to_be16(ETH_P_CAN),
878         .func = can_rcv,
879 };
880 
881 static struct packet_type canfd_packet __read_mostly = {
882         .type = cpu_to_be16(ETH_P_CANFD),
883         .func = canfd_rcv,
884 };
885 
886 static const struct net_proto_family can_family_ops = {
887         .family = PF_CAN,
888         .create = can_create,
889         .owner  = THIS_MODULE,
890 };
891 
892 /* notifier block for netdevice event */
893 static struct notifier_block can_netdev_notifier __read_mostly = {
894         .notifier_call = can_notifier,
895 };
896 
897 static __init int can_init(void)
898 {
899         /* check for correct padding to be able to use the structs similarly */
900         BUILD_BUG_ON(offsetof(struct can_frame, can_dlc) !=
901                      offsetof(struct canfd_frame, len) ||
902                      offsetof(struct can_frame, data) !=
903                      offsetof(struct canfd_frame, data));
904 
905         pr_info("can: controller area network core (" CAN_VERSION_STRING ")\n");
906 
907         memset(&can_rx_alldev_list, 0, sizeof(can_rx_alldev_list));
908 
909         rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
910                                       0, 0, NULL);
911         if (!rcv_cache)
912                 return -ENOMEM;
913 
914         if (stats_timer) {
915                 /* the statistics are updated every second (timer triggered) */
916                 setup_timer(&can_stattimer, can_stat_update, 0);
917                 mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
918         } else
919                 can_stattimer.function = NULL;
920 
921         can_init_proc();
922 
923         /* protocol register */
924         sock_register(&can_family_ops);
925         register_netdevice_notifier(&can_netdev_notifier);
926         dev_add_pack(&can_packet);
927         dev_add_pack(&canfd_packet);
928 
929         return 0;
930 }
931 
932 static __exit void can_exit(void)
933 {
934         struct net_device *dev;
935 
936         if (stats_timer)
937                 del_timer_sync(&can_stattimer);
938 
939         can_remove_proc();
940 
941         /* protocol unregister */
942         dev_remove_pack(&canfd_packet);
943         dev_remove_pack(&can_packet);
944         unregister_netdevice_notifier(&can_netdev_notifier);
945         sock_unregister(PF_CAN);
946 
947         /* remove created dev_rcv_lists from still registered CAN devices */
948         rcu_read_lock();
949         for_each_netdev_rcu(&init_net, dev) {
950                 if (dev->type == ARPHRD_CAN && dev->ml_priv) {
951 
952                         struct dev_rcv_lists *d = dev->ml_priv;
953 
954                         BUG_ON(d->entries);
955                         kfree(d);
956                         dev->ml_priv = NULL;
957                 }
958         }
959         rcu_read_unlock();
960 
961         rcu_barrier(); /* Wait for completion of call_rcu()'s */
962 
963         kmem_cache_destroy(rcv_cache);
964 }
965 
966 module_init(can_init);
967 module_exit(can_exit);
968 

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