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TOMOYO Linux Cross Reference
Linux/net/can/gw.c

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  1 /*
  2  * gw.c - CAN frame Gateway/Router/Bridge with netlink interface
  3  *
  4  * Copyright (c) 2011 Volkswagen Group Electronic Research
  5  * All rights reserved.
  6  *
  7  * Redistribution and use in source and binary forms, with or without
  8  * modification, are permitted provided that the following conditions
  9  * are met:
 10  * 1. Redistributions of source code must retain the above copyright
 11  *    notice, this list of conditions and the following disclaimer.
 12  * 2. Redistributions in binary form must reproduce the above copyright
 13  *    notice, this list of conditions and the following disclaimer in the
 14  *    documentation and/or other materials provided with the distribution.
 15  * 3. Neither the name of Volkswagen nor the names of its contributors
 16  *    may be used to endorse or promote products derived from this software
 17  *    without specific prior written permission.
 18  *
 19  * Alternatively, provided that this notice is retained in full, this
 20  * software may be distributed under the terms of the GNU General
 21  * Public License ("GPL") version 2, in which case the provisions of the
 22  * GPL apply INSTEAD OF those given above.
 23  *
 24  * The provided data structures and external interfaces from this code
 25  * are not restricted to be used by modules with a GPL compatible license.
 26  *
 27  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 28  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 29  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 30  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 31  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 32  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 33  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 37  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 38  * DAMAGE.
 39  *
 40  */
 41 
 42 #include <linux/module.h>
 43 #include <linux/init.h>
 44 #include <linux/types.h>
 45 #include <linux/kernel.h>
 46 #include <linux/list.h>
 47 #include <linux/spinlock.h>
 48 #include <linux/rcupdate.h>
 49 #include <linux/rculist.h>
 50 #include <linux/net.h>
 51 #include <linux/netdevice.h>
 52 #include <linux/if_arp.h>
 53 #include <linux/skbuff.h>
 54 #include <linux/can.h>
 55 #include <linux/can/core.h>
 56 #include <linux/can/skb.h>
 57 #include <linux/can/gw.h>
 58 #include <net/rtnetlink.h>
 59 #include <net/net_namespace.h>
 60 #include <net/sock.h>
 61 
 62 #define CAN_GW_VERSION "20130117"
 63 #define CAN_GW_NAME "can-gw"
 64 
 65 MODULE_DESCRIPTION("PF_CAN netlink gateway");
 66 MODULE_LICENSE("Dual BSD/GPL");
 67 MODULE_AUTHOR("Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
 68 MODULE_ALIAS(CAN_GW_NAME);
 69 
 70 #define CGW_MIN_HOPS 1
 71 #define CGW_MAX_HOPS 6
 72 #define CGW_DEFAULT_HOPS 1
 73 
 74 static unsigned int max_hops __read_mostly = CGW_DEFAULT_HOPS;
 75 module_param(max_hops, uint, S_IRUGO);
 76 MODULE_PARM_DESC(max_hops,
 77                  "maximum " CAN_GW_NAME " routing hops for CAN frames "
 78                  "(valid values: " __stringify(CGW_MIN_HOPS) "-"
 79                  __stringify(CGW_MAX_HOPS) " hops, "
 80                  "default: " __stringify(CGW_DEFAULT_HOPS) ")");
 81 
 82 static HLIST_HEAD(cgw_list);
 83 static struct notifier_block notifier;
 84 
 85 static struct kmem_cache *cgw_cache __read_mostly;
 86 
 87 /* structure that contains the (on-the-fly) CAN frame modifications */
 88 struct cf_mod {
 89         struct {
 90                 struct can_frame and;
 91                 struct can_frame or;
 92                 struct can_frame xor;
 93                 struct can_frame set;
 94         } modframe;
 95         struct {
 96                 u8 and;
 97                 u8 or;
 98                 u8 xor;
 99                 u8 set;
100         } modtype;
101         void (*modfunc[MAX_MODFUNCTIONS])(struct can_frame *cf,
102                                           struct cf_mod *mod);
103 
104         /* CAN frame checksum calculation after CAN frame modifications */
105         struct {
106                 struct cgw_csum_xor xor;
107                 struct cgw_csum_crc8 crc8;
108         } csum;
109         struct {
110                 void (*xor)(struct can_frame *cf, struct cgw_csum_xor *xor);
111                 void (*crc8)(struct can_frame *cf, struct cgw_csum_crc8 *crc8);
112         } csumfunc;
113 };
114 
115 
116 /*
117  * So far we just support CAN -> CAN routing and frame modifications.
118  *
119  * The internal can_can_gw structure contains data and attributes for
120  * a CAN -> CAN gateway job.
121  */
122 struct can_can_gw {
123         struct can_filter filter;
124         int src_idx;
125         int dst_idx;
126 };
127 
128 /* list entry for CAN gateways jobs */
129 struct cgw_job {
130         struct hlist_node list;
131         struct rcu_head rcu;
132         u32 handled_frames;
133         u32 dropped_frames;
134         u32 deleted_frames;
135         struct cf_mod mod;
136         union {
137                 /* CAN frame data source */
138                 struct net_device *dev;
139         } src;
140         union {
141                 /* CAN frame data destination */
142                 struct net_device *dev;
143         } dst;
144         union {
145                 struct can_can_gw ccgw;
146                 /* tbc */
147         };
148         u8 gwtype;
149         u8 limit_hops;
150         u16 flags;
151 };
152 
153 /* modification functions that are invoked in the hot path in can_can_gw_rcv */
154 
155 #define MODFUNC(func, op) static void func(struct can_frame *cf, \
156                                            struct cf_mod *mod) { op ; }
157 
158 MODFUNC(mod_and_id, cf->can_id &= mod->modframe.and.can_id)
159 MODFUNC(mod_and_dlc, cf->can_dlc &= mod->modframe.and.can_dlc)
160 MODFUNC(mod_and_data, *(u64 *)cf->data &= *(u64 *)mod->modframe.and.data)
161 MODFUNC(mod_or_id, cf->can_id |= mod->modframe.or.can_id)
162 MODFUNC(mod_or_dlc, cf->can_dlc |= mod->modframe.or.can_dlc)
163 MODFUNC(mod_or_data, *(u64 *)cf->data |= *(u64 *)mod->modframe.or.data)
164 MODFUNC(mod_xor_id, cf->can_id ^= mod->modframe.xor.can_id)
165 MODFUNC(mod_xor_dlc, cf->can_dlc ^= mod->modframe.xor.can_dlc)
166 MODFUNC(mod_xor_data, *(u64 *)cf->data ^= *(u64 *)mod->modframe.xor.data)
167 MODFUNC(mod_set_id, cf->can_id = mod->modframe.set.can_id)
168 MODFUNC(mod_set_dlc, cf->can_dlc = mod->modframe.set.can_dlc)
169 MODFUNC(mod_set_data, *(u64 *)cf->data = *(u64 *)mod->modframe.set.data)
170 
171 static inline void canframecpy(struct can_frame *dst, struct can_frame *src)
172 {
173         /*
174          * Copy the struct members separately to ensure that no uninitialized
175          * data are copied in the 3 bytes hole of the struct. This is needed
176          * to make easy compares of the data in the struct cf_mod.
177          */
178 
179         dst->can_id = src->can_id;
180         dst->can_dlc = src->can_dlc;
181         *(u64 *)dst->data = *(u64 *)src->data;
182 }
183 
184 static int cgw_chk_csum_parms(s8 fr, s8 to, s8 re)
185 {
186         /*
187          * absolute dlc values 0 .. 7 => 0 .. 7, e.g. data [0]
188          * relative to received dlc -1 .. -8 :
189          * e.g. for received dlc = 8
190          * -1 => index = 7 (data[7])
191          * -3 => index = 5 (data[5])
192          * -8 => index = 0 (data[0])
193          */
194 
195         if (fr > -9 && fr < 8 &&
196             to > -9 && to < 8 &&
197             re > -9 && re < 8)
198                 return 0;
199         else
200                 return -EINVAL;
201 }
202 
203 static inline int calc_idx(int idx, int rx_dlc)
204 {
205         if (idx < 0)
206                 return rx_dlc + idx;
207         else
208                 return idx;
209 }
210 
211 static void cgw_csum_xor_rel(struct can_frame *cf, struct cgw_csum_xor *xor)
212 {
213         int from = calc_idx(xor->from_idx, cf->can_dlc);
214         int to = calc_idx(xor->to_idx, cf->can_dlc);
215         int res = calc_idx(xor->result_idx, cf->can_dlc);
216         u8 val = xor->init_xor_val;
217         int i;
218 
219         if (from < 0 || to < 0 || res < 0)
220                 return;
221 
222         if (from <= to) {
223                 for (i = from; i <= to; i++)
224                         val ^= cf->data[i];
225         } else {
226                 for (i = from; i >= to; i--)
227                         val ^= cf->data[i];
228         }
229 
230         cf->data[res] = val;
231 }
232 
233 static void cgw_csum_xor_pos(struct can_frame *cf, struct cgw_csum_xor *xor)
234 {
235         u8 val = xor->init_xor_val;
236         int i;
237 
238         for (i = xor->from_idx; i <= xor->to_idx; i++)
239                 val ^= cf->data[i];
240 
241         cf->data[xor->result_idx] = val;
242 }
243 
244 static void cgw_csum_xor_neg(struct can_frame *cf, struct cgw_csum_xor *xor)
245 {
246         u8 val = xor->init_xor_val;
247         int i;
248 
249         for (i = xor->from_idx; i >= xor->to_idx; i--)
250                 val ^= cf->data[i];
251 
252         cf->data[xor->result_idx] = val;
253 }
254 
255 static void cgw_csum_crc8_rel(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
256 {
257         int from = calc_idx(crc8->from_idx, cf->can_dlc);
258         int to = calc_idx(crc8->to_idx, cf->can_dlc);
259         int res = calc_idx(crc8->result_idx, cf->can_dlc);
260         u8 crc = crc8->init_crc_val;
261         int i;
262 
263         if (from < 0 || to < 0 || res < 0)
264                 return;
265 
266         if (from <= to) {
267                 for (i = crc8->from_idx; i <= crc8->to_idx; i++)
268                         crc = crc8->crctab[crc^cf->data[i]];
269         } else {
270                 for (i = crc8->from_idx; i >= crc8->to_idx; i--)
271                         crc = crc8->crctab[crc^cf->data[i]];
272         }
273 
274         switch (crc8->profile) {
275 
276         case CGW_CRC8PRF_1U8:
277                 crc = crc8->crctab[crc^crc8->profile_data[0]];
278                 break;
279 
280         case  CGW_CRC8PRF_16U8:
281                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
282                 break;
283 
284         case CGW_CRC8PRF_SFFID_XOR:
285                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
286                                    (cf->can_id >> 8 & 0xFF)];
287                 break;
288 
289         }
290 
291         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
292 }
293 
294 static void cgw_csum_crc8_pos(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
295 {
296         u8 crc = crc8->init_crc_val;
297         int i;
298 
299         for (i = crc8->from_idx; i <= crc8->to_idx; i++)
300                 crc = crc8->crctab[crc^cf->data[i]];
301 
302         switch (crc8->profile) {
303 
304         case CGW_CRC8PRF_1U8:
305                 crc = crc8->crctab[crc^crc8->profile_data[0]];
306                 break;
307 
308         case  CGW_CRC8PRF_16U8:
309                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
310                 break;
311 
312         case CGW_CRC8PRF_SFFID_XOR:
313                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
314                                    (cf->can_id >> 8 & 0xFF)];
315                 break;
316         }
317 
318         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
319 }
320 
321 static void cgw_csum_crc8_neg(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
322 {
323         u8 crc = crc8->init_crc_val;
324         int i;
325 
326         for (i = crc8->from_idx; i >= crc8->to_idx; i--)
327                 crc = crc8->crctab[crc^cf->data[i]];
328 
329         switch (crc8->profile) {
330 
331         case CGW_CRC8PRF_1U8:
332                 crc = crc8->crctab[crc^crc8->profile_data[0]];
333                 break;
334 
335         case  CGW_CRC8PRF_16U8:
336                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
337                 break;
338 
339         case CGW_CRC8PRF_SFFID_XOR:
340                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
341                                    (cf->can_id >> 8 & 0xFF)];
342                 break;
343         }
344 
345         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
346 }
347 
348 /* the receive & process & send function */
349 static void can_can_gw_rcv(struct sk_buff *skb, void *data)
350 {
351         struct cgw_job *gwj = (struct cgw_job *)data;
352         struct can_frame *cf;
353         struct sk_buff *nskb;
354         int modidx = 0;
355 
356         /*
357          * Do not handle CAN frames routed more than 'max_hops' times.
358          * In general we should never catch this delimiter which is intended
359          * to cover a misconfiguration protection (e.g. circular CAN routes).
360          *
361          * The Controller Area Network controllers only accept CAN frames with
362          * correct CRCs - which are not visible in the controller registers.
363          * According to skbuff.h documentation the csum_start element for IP
364          * checksums is undefined/unsued when ip_summed == CHECKSUM_UNNECESSARY.
365          * Only CAN skbs can be processed here which already have this property.
366          */
367 
368 #define cgw_hops(skb) ((skb)->csum_start)
369 
370         BUG_ON(skb->ip_summed != CHECKSUM_UNNECESSARY);
371 
372         if (cgw_hops(skb) >= max_hops) {
373                 /* indicate deleted frames due to misconfiguration */
374                 gwj->deleted_frames++;
375                 return;
376         }
377 
378         if (!(gwj->dst.dev->flags & IFF_UP)) {
379                 gwj->dropped_frames++;
380                 return;
381         }
382 
383         /* is sending the skb back to the incoming interface not allowed? */
384         if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
385             can_skb_prv(skb)->ifindex == gwj->dst.dev->ifindex)
386                 return;
387 
388         /*
389          * clone the given skb, which has not been done in can_rcv()
390          *
391          * When there is at least one modification function activated,
392          * we need to copy the skb as we want to modify skb->data.
393          */
394         if (gwj->mod.modfunc[0])
395                 nskb = skb_copy(skb, GFP_ATOMIC);
396         else
397                 nskb = skb_clone(skb, GFP_ATOMIC);
398 
399         if (!nskb) {
400                 gwj->dropped_frames++;
401                 return;
402         }
403 
404         /* put the incremented hop counter in the cloned skb */
405         cgw_hops(nskb) = cgw_hops(skb) + 1;
406 
407         /* first processing of this CAN frame -> adjust to private hop limit */
408         if (gwj->limit_hops && cgw_hops(nskb) == 1)
409                 cgw_hops(nskb) = max_hops - gwj->limit_hops + 1;
410 
411         nskb->dev = gwj->dst.dev;
412 
413         /* pointer to modifiable CAN frame */
414         cf = (struct can_frame *)nskb->data;
415 
416         /* perform preprocessed modification functions if there are any */
417         while (modidx < MAX_MODFUNCTIONS && gwj->mod.modfunc[modidx])
418                 (*gwj->mod.modfunc[modidx++])(cf, &gwj->mod);
419 
420         /* check for checksum updates when the CAN frame has been modified */
421         if (modidx) {
422                 if (gwj->mod.csumfunc.crc8)
423                         (*gwj->mod.csumfunc.crc8)(cf, &gwj->mod.csum.crc8);
424 
425                 if (gwj->mod.csumfunc.xor)
426                         (*gwj->mod.csumfunc.xor)(cf, &gwj->mod.csum.xor);
427         }
428 
429         /* clear the skb timestamp if not configured the other way */
430         if (!(gwj->flags & CGW_FLAGS_CAN_SRC_TSTAMP))
431                 nskb->tstamp.tv64 = 0;
432 
433         /* send to netdevice */
434         if (can_send(nskb, gwj->flags & CGW_FLAGS_CAN_ECHO))
435                 gwj->dropped_frames++;
436         else
437                 gwj->handled_frames++;
438 }
439 
440 static inline int cgw_register_filter(struct cgw_job *gwj)
441 {
442         return can_rx_register(gwj->src.dev, gwj->ccgw.filter.can_id,
443                                gwj->ccgw.filter.can_mask, can_can_gw_rcv,
444                                gwj, "gw");
445 }
446 
447 static inline void cgw_unregister_filter(struct cgw_job *gwj)
448 {
449         can_rx_unregister(gwj->src.dev, gwj->ccgw.filter.can_id,
450                           gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
451 }
452 
453 static int cgw_notifier(struct notifier_block *nb,
454                         unsigned long msg, void *ptr)
455 {
456         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
457 
458         if (!net_eq(dev_net(dev), &init_net))
459                 return NOTIFY_DONE;
460         if (dev->type != ARPHRD_CAN)
461                 return NOTIFY_DONE;
462 
463         if (msg == NETDEV_UNREGISTER) {
464 
465                 struct cgw_job *gwj = NULL;
466                 struct hlist_node *nx;
467 
468                 ASSERT_RTNL();
469 
470                 hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
471 
472                         if (gwj->src.dev == dev || gwj->dst.dev == dev) {
473                                 hlist_del(&gwj->list);
474                                 cgw_unregister_filter(gwj);
475                                 kmem_cache_free(cgw_cache, gwj);
476                         }
477                 }
478         }
479 
480         return NOTIFY_DONE;
481 }
482 
483 static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
484                        u32 pid, u32 seq, int flags)
485 {
486         struct cgw_frame_mod mb;
487         struct rtcanmsg *rtcan;
488         struct nlmsghdr *nlh;
489 
490         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
491         if (!nlh)
492                 return -EMSGSIZE;
493 
494         rtcan = nlmsg_data(nlh);
495         rtcan->can_family = AF_CAN;
496         rtcan->gwtype = gwj->gwtype;
497         rtcan->flags = gwj->flags;
498 
499         /* add statistics if available */
500 
501         if (gwj->handled_frames) {
502                 if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
503                         goto cancel;
504         }
505 
506         if (gwj->dropped_frames) {
507                 if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
508                         goto cancel;
509         }
510 
511         if (gwj->deleted_frames) {
512                 if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
513                         goto cancel;
514         }
515 
516         /* check non default settings of attributes */
517 
518         if (gwj->limit_hops) {
519                 if (nla_put_u8(skb, CGW_LIM_HOPS, gwj->limit_hops) < 0)
520                         goto cancel;
521         }
522 
523         if (gwj->mod.modtype.and) {
524                 memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
525                 mb.modtype = gwj->mod.modtype.and;
526                 if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
527                         goto cancel;
528         }
529 
530         if (gwj->mod.modtype.or) {
531                 memcpy(&mb.cf, &gwj->mod.modframe.or, sizeof(mb.cf));
532                 mb.modtype = gwj->mod.modtype.or;
533                 if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
534                         goto cancel;
535         }
536 
537         if (gwj->mod.modtype.xor) {
538                 memcpy(&mb.cf, &gwj->mod.modframe.xor, sizeof(mb.cf));
539                 mb.modtype = gwj->mod.modtype.xor;
540                 if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
541                         goto cancel;
542         }
543 
544         if (gwj->mod.modtype.set) {
545                 memcpy(&mb.cf, &gwj->mod.modframe.set, sizeof(mb.cf));
546                 mb.modtype = gwj->mod.modtype.set;
547                 if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
548                         goto cancel;
549         }
550 
551         if (gwj->mod.csumfunc.crc8) {
552                 if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
553                             &gwj->mod.csum.crc8) < 0)
554                         goto cancel;
555         }
556 
557         if (gwj->mod.csumfunc.xor) {
558                 if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
559                             &gwj->mod.csum.xor) < 0)
560                         goto cancel;
561         }
562 
563         if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
564 
565                 if (gwj->ccgw.filter.can_id || gwj->ccgw.filter.can_mask) {
566                         if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
567                                     &gwj->ccgw.filter) < 0)
568                                 goto cancel;
569                 }
570 
571                 if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
572                         goto cancel;
573 
574                 if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
575                         goto cancel;
576         }
577 
578         return nlmsg_end(skb, nlh);
579 
580 cancel:
581         nlmsg_cancel(skb, nlh);
582         return -EMSGSIZE;
583 }
584 
585 /* Dump information about all CAN gateway jobs, in response to RTM_GETROUTE */
586 static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
587 {
588         struct cgw_job *gwj = NULL;
589         int idx = 0;
590         int s_idx = cb->args[0];
591 
592         rcu_read_lock();
593         hlist_for_each_entry_rcu(gwj, &cgw_list, list) {
594                 if (idx < s_idx)
595                         goto cont;
596 
597                 if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).portid,
598                     cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
599                         break;
600 cont:
601                 idx++;
602         }
603         rcu_read_unlock();
604 
605         cb->args[0] = idx;
606 
607         return skb->len;
608 }
609 
610 static const struct nla_policy cgw_policy[CGW_MAX+1] = {
611         [CGW_MOD_AND]   = { .len = sizeof(struct cgw_frame_mod) },
612         [CGW_MOD_OR]    = { .len = sizeof(struct cgw_frame_mod) },
613         [CGW_MOD_XOR]   = { .len = sizeof(struct cgw_frame_mod) },
614         [CGW_MOD_SET]   = { .len = sizeof(struct cgw_frame_mod) },
615         [CGW_CS_XOR]    = { .len = sizeof(struct cgw_csum_xor) },
616         [CGW_CS_CRC8]   = { .len = sizeof(struct cgw_csum_crc8) },
617         [CGW_SRC_IF]    = { .type = NLA_U32 },
618         [CGW_DST_IF]    = { .type = NLA_U32 },
619         [CGW_FILTER]    = { .len = sizeof(struct can_filter) },
620         [CGW_LIM_HOPS]  = { .type = NLA_U8 },
621 };
622 
623 /* check for common and gwtype specific attributes */
624 static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
625                           u8 gwtype, void *gwtypeattr, u8 *limhops)
626 {
627         struct nlattr *tb[CGW_MAX+1];
628         struct cgw_frame_mod mb;
629         int modidx = 0;
630         int err = 0;
631 
632         /* initialize modification & checksum data space */
633         memset(mod, 0, sizeof(*mod));
634 
635         err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
636                           cgw_policy);
637         if (err < 0)
638                 return err;
639 
640         if (tb[CGW_LIM_HOPS]) {
641                 *limhops = nla_get_u8(tb[CGW_LIM_HOPS]);
642 
643                 if (*limhops < 1 || *limhops > max_hops)
644                         return -EINVAL;
645         }
646 
647         /* check for AND/OR/XOR/SET modifications */
648 
649         if (tb[CGW_MOD_AND]) {
650                 nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
651 
652                 canframecpy(&mod->modframe.and, &mb.cf);
653                 mod->modtype.and = mb.modtype;
654 
655                 if (mb.modtype & CGW_MOD_ID)
656                         mod->modfunc[modidx++] = mod_and_id;
657 
658                 if (mb.modtype & CGW_MOD_DLC)
659                         mod->modfunc[modidx++] = mod_and_dlc;
660 
661                 if (mb.modtype & CGW_MOD_DATA)
662                         mod->modfunc[modidx++] = mod_and_data;
663         }
664 
665         if (tb[CGW_MOD_OR]) {
666                 nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
667 
668                 canframecpy(&mod->modframe.or, &mb.cf);
669                 mod->modtype.or = mb.modtype;
670 
671                 if (mb.modtype & CGW_MOD_ID)
672                         mod->modfunc[modidx++] = mod_or_id;
673 
674                 if (mb.modtype & CGW_MOD_DLC)
675                         mod->modfunc[modidx++] = mod_or_dlc;
676 
677                 if (mb.modtype & CGW_MOD_DATA)
678                         mod->modfunc[modidx++] = mod_or_data;
679         }
680 
681         if (tb[CGW_MOD_XOR]) {
682                 nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
683 
684                 canframecpy(&mod->modframe.xor, &mb.cf);
685                 mod->modtype.xor = mb.modtype;
686 
687                 if (mb.modtype & CGW_MOD_ID)
688                         mod->modfunc[modidx++] = mod_xor_id;
689 
690                 if (mb.modtype & CGW_MOD_DLC)
691                         mod->modfunc[modidx++] = mod_xor_dlc;
692 
693                 if (mb.modtype & CGW_MOD_DATA)
694                         mod->modfunc[modidx++] = mod_xor_data;
695         }
696 
697         if (tb[CGW_MOD_SET]) {
698                 nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
699 
700                 canframecpy(&mod->modframe.set, &mb.cf);
701                 mod->modtype.set = mb.modtype;
702 
703                 if (mb.modtype & CGW_MOD_ID)
704                         mod->modfunc[modidx++] = mod_set_id;
705 
706                 if (mb.modtype & CGW_MOD_DLC)
707                         mod->modfunc[modidx++] = mod_set_dlc;
708 
709                 if (mb.modtype & CGW_MOD_DATA)
710                         mod->modfunc[modidx++] = mod_set_data;
711         }
712 
713         /* check for checksum operations after CAN frame modifications */
714         if (modidx) {
715 
716                 if (tb[CGW_CS_CRC8]) {
717                         struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
718 
719                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
720                                                  c->result_idx);
721                         if (err)
722                                 return err;
723 
724                         nla_memcpy(&mod->csum.crc8, tb[CGW_CS_CRC8],
725                                    CGW_CS_CRC8_LEN);
726 
727                         /*
728                          * select dedicated processing function to reduce
729                          * runtime operations in receive hot path.
730                          */
731                         if (c->from_idx < 0 || c->to_idx < 0 ||
732                             c->result_idx < 0)
733                                 mod->csumfunc.crc8 = cgw_csum_crc8_rel;
734                         else if (c->from_idx <= c->to_idx)
735                                 mod->csumfunc.crc8 = cgw_csum_crc8_pos;
736                         else
737                                 mod->csumfunc.crc8 = cgw_csum_crc8_neg;
738                 }
739 
740                 if (tb[CGW_CS_XOR]) {
741                         struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
742 
743                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
744                                                  c->result_idx);
745                         if (err)
746                                 return err;
747 
748                         nla_memcpy(&mod->csum.xor, tb[CGW_CS_XOR],
749                                    CGW_CS_XOR_LEN);
750 
751                         /*
752                          * select dedicated processing function to reduce
753                          * runtime operations in receive hot path.
754                          */
755                         if (c->from_idx < 0 || c->to_idx < 0 ||
756                             c->result_idx < 0)
757                                 mod->csumfunc.xor = cgw_csum_xor_rel;
758                         else if (c->from_idx <= c->to_idx)
759                                 mod->csumfunc.xor = cgw_csum_xor_pos;
760                         else
761                                 mod->csumfunc.xor = cgw_csum_xor_neg;
762                 }
763         }
764 
765         if (gwtype == CGW_TYPE_CAN_CAN) {
766 
767                 /* check CGW_TYPE_CAN_CAN specific attributes */
768 
769                 struct can_can_gw *ccgw = (struct can_can_gw *)gwtypeattr;
770                 memset(ccgw, 0, sizeof(*ccgw));
771 
772                 /* check for can_filter in attributes */
773                 if (tb[CGW_FILTER])
774                         nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
775                                    sizeof(struct can_filter));
776 
777                 err = -ENODEV;
778 
779                 /* specifying two interfaces is mandatory */
780                 if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
781                         return err;
782 
783                 ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
784                 ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
785 
786                 /* both indices set to 0 for flushing all routing entries */
787                 if (!ccgw->src_idx && !ccgw->dst_idx)
788                         return 0;
789 
790                 /* only one index set to 0 is an error */
791                 if (!ccgw->src_idx || !ccgw->dst_idx)
792                         return err;
793         }
794 
795         /* add the checks for other gwtypes here */
796 
797         return 0;
798 }
799 
800 static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
801 {
802         struct rtcanmsg *r;
803         struct cgw_job *gwj;
804         u8 limhops = 0;
805         int err = 0;
806 
807         if (!netlink_capable(skb, CAP_NET_ADMIN))
808                 return -EPERM;
809 
810         if (nlmsg_len(nlh) < sizeof(*r))
811                 return -EINVAL;
812 
813         r = nlmsg_data(nlh);
814         if (r->can_family != AF_CAN)
815                 return -EPFNOSUPPORT;
816 
817         /* so far we only support CAN -> CAN routings */
818         if (r->gwtype != CGW_TYPE_CAN_CAN)
819                 return -EINVAL;
820 
821         gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
822         if (!gwj)
823                 return -ENOMEM;
824 
825         gwj->handled_frames = 0;
826         gwj->dropped_frames = 0;
827         gwj->deleted_frames = 0;
828         gwj->flags = r->flags;
829         gwj->gwtype = r->gwtype;
830 
831         err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw,
832                              &limhops);
833         if (err < 0)
834                 goto out;
835 
836         err = -ENODEV;
837 
838         /* ifindex == 0 is not allowed for job creation */
839         if (!gwj->ccgw.src_idx || !gwj->ccgw.dst_idx)
840                 goto out;
841 
842         gwj->src.dev = __dev_get_by_index(&init_net, gwj->ccgw.src_idx);
843 
844         if (!gwj->src.dev)
845                 goto out;
846 
847         if (gwj->src.dev->type != ARPHRD_CAN)
848                 goto out;
849 
850         gwj->dst.dev = __dev_get_by_index(&init_net, gwj->ccgw.dst_idx);
851 
852         if (!gwj->dst.dev)
853                 goto out;
854 
855         if (gwj->dst.dev->type != ARPHRD_CAN)
856                 goto out;
857 
858         gwj->limit_hops = limhops;
859 
860         ASSERT_RTNL();
861 
862         err = cgw_register_filter(gwj);
863         if (!err)
864                 hlist_add_head_rcu(&gwj->list, &cgw_list);
865 out:
866         if (err)
867                 kmem_cache_free(cgw_cache, gwj);
868 
869         return err;
870 }
871 
872 static void cgw_remove_all_jobs(void)
873 {
874         struct cgw_job *gwj = NULL;
875         struct hlist_node *nx;
876 
877         ASSERT_RTNL();
878 
879         hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
880                 hlist_del(&gwj->list);
881                 cgw_unregister_filter(gwj);
882                 kmem_cache_free(cgw_cache, gwj);
883         }
884 }
885 
886 static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh)
887 {
888         struct cgw_job *gwj = NULL;
889         struct hlist_node *nx;
890         struct rtcanmsg *r;
891         struct cf_mod mod;
892         struct can_can_gw ccgw;
893         u8 limhops = 0;
894         int err = 0;
895 
896         if (!netlink_capable(skb, CAP_NET_ADMIN))
897                 return -EPERM;
898 
899         if (nlmsg_len(nlh) < sizeof(*r))
900                 return -EINVAL;
901 
902         r = nlmsg_data(nlh);
903         if (r->can_family != AF_CAN)
904                 return -EPFNOSUPPORT;
905 
906         /* so far we only support CAN -> CAN routings */
907         if (r->gwtype != CGW_TYPE_CAN_CAN)
908                 return -EINVAL;
909 
910         err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
911         if (err < 0)
912                 return err;
913 
914         /* two interface indices both set to 0 => remove all entries */
915         if (!ccgw.src_idx && !ccgw.dst_idx) {
916                 cgw_remove_all_jobs();
917                 return 0;
918         }
919 
920         err = -EINVAL;
921 
922         ASSERT_RTNL();
923 
924         /* remove only the first matching entry */
925         hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
926 
927                 if (gwj->flags != r->flags)
928                         continue;
929 
930                 if (gwj->limit_hops != limhops)
931                         continue;
932 
933                 if (memcmp(&gwj->mod, &mod, sizeof(mod)))
934                         continue;
935 
936                 /* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
937                 if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
938                         continue;
939 
940                 hlist_del(&gwj->list);
941                 cgw_unregister_filter(gwj);
942                 kmem_cache_free(cgw_cache, gwj);
943                 err = 0;
944                 break;
945         }
946 
947         return err;
948 }
949 
950 static __init int cgw_module_init(void)
951 {
952         /* sanitize given module parameter */
953         max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
954 
955         pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
956                 max_hops);
957 
958         cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
959                                       0, 0, NULL);
960 
961         if (!cgw_cache)
962                 return -ENOMEM;
963 
964         /* set notifier */
965         notifier.notifier_call = cgw_notifier;
966         register_netdevice_notifier(&notifier);
967 
968         if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, NULL)) {
969                 unregister_netdevice_notifier(&notifier);
970                 kmem_cache_destroy(cgw_cache);
971                 return -ENOBUFS;
972         }
973 
974         /* Only the first call to __rtnl_register can fail */
975         __rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, NULL);
976         __rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, NULL);
977 
978         return 0;
979 }
980 
981 static __exit void cgw_module_exit(void)
982 {
983         rtnl_unregister_all(PF_CAN);
984 
985         unregister_netdevice_notifier(&notifier);
986 
987         rtnl_lock();
988         cgw_remove_all_jobs();
989         rtnl_unlock();
990 
991         rcu_barrier(); /* Wait for completion of call_rcu()'s */
992 
993         kmem_cache_destroy(cgw_cache);
994 }
995 
996 module_init(cgw_module_init);
997 module_exit(cgw_module_exit);
998 

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