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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) 2017 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 "20170425"
 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, 0444);
 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 struct notifier_block notifier;
 83 static struct kmem_cache *cgw_cache __read_mostly;
 84 
 85 /* structure that contains the (on-the-fly) CAN frame modifications */
 86 struct cf_mod {
 87         struct {
 88                 struct can_frame and;
 89                 struct can_frame or;
 90                 struct can_frame xor;
 91                 struct can_frame set;
 92         } modframe;
 93         struct {
 94                 u8 and;
 95                 u8 or;
 96                 u8 xor;
 97                 u8 set;
 98         } modtype;
 99         void (*modfunc[MAX_MODFUNCTIONS])(struct can_frame *cf,
100                                           struct cf_mod *mod);
101 
102         /* CAN frame checksum calculation after CAN frame modifications */
103         struct {
104                 struct cgw_csum_xor xor;
105                 struct cgw_csum_crc8 crc8;
106         } csum;
107         struct {
108                 void (*xor)(struct can_frame *cf, struct cgw_csum_xor *xor);
109                 void (*crc8)(struct can_frame *cf, struct cgw_csum_crc8 *crc8);
110         } csumfunc;
111         u32 uid;
112 };
113 
114 
115 /*
116  * So far we just support CAN -> CAN routing and frame modifications.
117  *
118  * The internal can_can_gw structure contains data and attributes for
119  * a CAN -> CAN gateway job.
120  */
121 struct can_can_gw {
122         struct can_filter filter;
123         int src_idx;
124         int dst_idx;
125 };
126 
127 /* list entry for CAN gateways jobs */
128 struct cgw_job {
129         struct hlist_node list;
130         struct rcu_head rcu;
131         u32 handled_frames;
132         u32 dropped_frames;
133         u32 deleted_frames;
134         struct cf_mod mod;
135         union {
136                 /* CAN frame data source */
137                 struct net_device *dev;
138         } src;
139         union {
140                 /* CAN frame data destination */
141                 struct net_device *dev;
142         } dst;
143         union {
144                 struct can_can_gw ccgw;
145                 /* tbc */
146         };
147         u8 gwtype;
148         u8 limit_hops;
149         u16 flags;
150 };
151 
152 /* modification functions that are invoked in the hot path in can_can_gw_rcv */
153 
154 #define MODFUNC(func, op) static void func(struct can_frame *cf, \
155                                            struct cf_mod *mod) { op ; }
156 
157 MODFUNC(mod_and_id, cf->can_id &= mod->modframe.and.can_id)
158 MODFUNC(mod_and_dlc, cf->can_dlc &= mod->modframe.and.can_dlc)
159 MODFUNC(mod_and_data, *(u64 *)cf->data &= *(u64 *)mod->modframe.and.data)
160 MODFUNC(mod_or_id, cf->can_id |= mod->modframe.or.can_id)
161 MODFUNC(mod_or_dlc, cf->can_dlc |= mod->modframe.or.can_dlc)
162 MODFUNC(mod_or_data, *(u64 *)cf->data |= *(u64 *)mod->modframe.or.data)
163 MODFUNC(mod_xor_id, cf->can_id ^= mod->modframe.xor.can_id)
164 MODFUNC(mod_xor_dlc, cf->can_dlc ^= mod->modframe.xor.can_dlc)
165 MODFUNC(mod_xor_data, *(u64 *)cf->data ^= *(u64 *)mod->modframe.xor.data)
166 MODFUNC(mod_set_id, cf->can_id = mod->modframe.set.can_id)
167 MODFUNC(mod_set_dlc, cf->can_dlc = mod->modframe.set.can_dlc)
168 MODFUNC(mod_set_data, *(u64 *)cf->data = *(u64 *)mod->modframe.set.data)
169 
170 static inline void canframecpy(struct can_frame *dst, struct can_frame *src)
171 {
172         /*
173          * Copy the struct members separately to ensure that no uninitialized
174          * data are copied in the 3 bytes hole of the struct. This is needed
175          * to make easy compares of the data in the struct cf_mod.
176          */
177 
178         dst->can_id = src->can_id;
179         dst->can_dlc = src->can_dlc;
180         *(u64 *)dst->data = *(u64 *)src->data;
181 }
182 
183 static int cgw_chk_csum_parms(s8 fr, s8 to, s8 re)
184 {
185         /*
186          * absolute dlc values 0 .. 7 => 0 .. 7, e.g. data [0]
187          * relative to received dlc -1 .. -8 :
188          * e.g. for received dlc = 8
189          * -1 => index = 7 (data[7])
190          * -3 => index = 5 (data[5])
191          * -8 => index = 0 (data[0])
192          */
193 
194         if (fr > -9 && fr < 8 &&
195             to > -9 && to < 8 &&
196             re > -9 && re < 8)
197                 return 0;
198         else
199                 return -EINVAL;
200 }
201 
202 static inline int calc_idx(int idx, int rx_dlc)
203 {
204         if (idx < 0)
205                 return rx_dlc + idx;
206         else
207                 return idx;
208 }
209 
210 static void cgw_csum_xor_rel(struct can_frame *cf, struct cgw_csum_xor *xor)
211 {
212         int from = calc_idx(xor->from_idx, cf->can_dlc);
213         int to = calc_idx(xor->to_idx, cf->can_dlc);
214         int res = calc_idx(xor->result_idx, cf->can_dlc);
215         u8 val = xor->init_xor_val;
216         int i;
217 
218         if (from < 0 || to < 0 || res < 0)
219                 return;
220 
221         if (from <= to) {
222                 for (i = from; i <= to; i++)
223                         val ^= cf->data[i];
224         } else {
225                 for (i = from; i >= to; i--)
226                         val ^= cf->data[i];
227         }
228 
229         cf->data[res] = val;
230 }
231 
232 static void cgw_csum_xor_pos(struct can_frame *cf, struct cgw_csum_xor *xor)
233 {
234         u8 val = xor->init_xor_val;
235         int i;
236 
237         for (i = xor->from_idx; i <= xor->to_idx; i++)
238                 val ^= cf->data[i];
239 
240         cf->data[xor->result_idx] = val;
241 }
242 
243 static void cgw_csum_xor_neg(struct can_frame *cf, struct cgw_csum_xor *xor)
244 {
245         u8 val = xor->init_xor_val;
246         int i;
247 
248         for (i = xor->from_idx; i >= xor->to_idx; i--)
249                 val ^= cf->data[i];
250 
251         cf->data[xor->result_idx] = val;
252 }
253 
254 static void cgw_csum_crc8_rel(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
255 {
256         int from = calc_idx(crc8->from_idx, cf->can_dlc);
257         int to = calc_idx(crc8->to_idx, cf->can_dlc);
258         int res = calc_idx(crc8->result_idx, cf->can_dlc);
259         u8 crc = crc8->init_crc_val;
260         int i;
261 
262         if (from < 0 || to < 0 || res < 0)
263                 return;
264 
265         if (from <= to) {
266                 for (i = crc8->from_idx; i <= crc8->to_idx; i++)
267                         crc = crc8->crctab[crc^cf->data[i]];
268         } else {
269                 for (i = crc8->from_idx; i >= crc8->to_idx; i--)
270                         crc = crc8->crctab[crc^cf->data[i]];
271         }
272 
273         switch (crc8->profile) {
274 
275         case CGW_CRC8PRF_1U8:
276                 crc = crc8->crctab[crc^crc8->profile_data[0]];
277                 break;
278 
279         case  CGW_CRC8PRF_16U8:
280                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
281                 break;
282 
283         case CGW_CRC8PRF_SFFID_XOR:
284                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
285                                    (cf->can_id >> 8 & 0xFF)];
286                 break;
287 
288         }
289 
290         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
291 }
292 
293 static void cgw_csum_crc8_pos(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
294 {
295         u8 crc = crc8->init_crc_val;
296         int i;
297 
298         for (i = crc8->from_idx; i <= crc8->to_idx; i++)
299                 crc = crc8->crctab[crc^cf->data[i]];
300 
301         switch (crc8->profile) {
302 
303         case CGW_CRC8PRF_1U8:
304                 crc = crc8->crctab[crc^crc8->profile_data[0]];
305                 break;
306 
307         case  CGW_CRC8PRF_16U8:
308                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
309                 break;
310 
311         case CGW_CRC8PRF_SFFID_XOR:
312                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
313                                    (cf->can_id >> 8 & 0xFF)];
314                 break;
315         }
316 
317         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
318 }
319 
320 static void cgw_csum_crc8_neg(struct can_frame *cf, struct cgw_csum_crc8 *crc8)
321 {
322         u8 crc = crc8->init_crc_val;
323         int i;
324 
325         for (i = crc8->from_idx; i >= crc8->to_idx; i--)
326                 crc = crc8->crctab[crc^cf->data[i]];
327 
328         switch (crc8->profile) {
329 
330         case CGW_CRC8PRF_1U8:
331                 crc = crc8->crctab[crc^crc8->profile_data[0]];
332                 break;
333 
334         case  CGW_CRC8PRF_16U8:
335                 crc = crc8->crctab[crc^crc8->profile_data[cf->data[1] & 0xF]];
336                 break;
337 
338         case CGW_CRC8PRF_SFFID_XOR:
339                 crc = crc8->crctab[crc^(cf->can_id & 0xFF)^
340                                    (cf->can_id >> 8 & 0xFF)];
341                 break;
342         }
343 
344         cf->data[crc8->result_idx] = crc^crc8->final_xor_val;
345 }
346 
347 /* the receive & process & send function */
348 static void can_can_gw_rcv(struct sk_buff *skb, void *data)
349 {
350         struct cgw_job *gwj = (struct cgw_job *)data;
351         struct can_frame *cf;
352         struct sk_buff *nskb;
353         int modidx = 0;
354 
355         /*
356          * Do not handle CAN frames routed more than 'max_hops' times.
357          * In general we should never catch this delimiter which is intended
358          * to cover a misconfiguration protection (e.g. circular CAN routes).
359          *
360          * The Controller Area Network controllers only accept CAN frames with
361          * correct CRCs - which are not visible in the controller registers.
362          * According to skbuff.h documentation the csum_start element for IP
363          * checksums is undefined/unused when ip_summed == CHECKSUM_UNNECESSARY.
364          * Only CAN skbs can be processed here which already have this property.
365          */
366 
367 #define cgw_hops(skb) ((skb)->csum_start)
368 
369         BUG_ON(skb->ip_summed != CHECKSUM_UNNECESSARY);
370 
371         if (cgw_hops(skb) >= max_hops) {
372                 /* indicate deleted frames due to misconfiguration */
373                 gwj->deleted_frames++;
374                 return;
375         }
376 
377         if (!(gwj->dst.dev->flags & IFF_UP)) {
378                 gwj->dropped_frames++;
379                 return;
380         }
381 
382         /* is sending the skb back to the incoming interface not allowed? */
383         if (!(gwj->flags & CGW_FLAGS_CAN_IIF_TX_OK) &&
384             can_skb_prv(skb)->ifindex == gwj->dst.dev->ifindex)
385                 return;
386 
387         /*
388          * clone the given skb, which has not been done in can_rcv()
389          *
390          * When there is at least one modification function activated,
391          * we need to copy the skb as we want to modify skb->data.
392          */
393         if (gwj->mod.modfunc[0])
394                 nskb = skb_copy(skb, GFP_ATOMIC);
395         else
396                 nskb = skb_clone(skb, GFP_ATOMIC);
397 
398         if (!nskb) {
399                 gwj->dropped_frames++;
400                 return;
401         }
402 
403         /* put the incremented hop counter in the cloned skb */
404         cgw_hops(nskb) = cgw_hops(skb) + 1;
405 
406         /* first processing of this CAN frame -> adjust to private hop limit */
407         if (gwj->limit_hops && cgw_hops(nskb) == 1)
408                 cgw_hops(nskb) = max_hops - gwj->limit_hops + 1;
409 
410         nskb->dev = gwj->dst.dev;
411 
412         /* pointer to modifiable CAN frame */
413         cf = (struct can_frame *)nskb->data;
414 
415         /* perform preprocessed modification functions if there are any */
416         while (modidx < MAX_MODFUNCTIONS && gwj->mod.modfunc[modidx])
417                 (*gwj->mod.modfunc[modidx++])(cf, &gwj->mod);
418 
419         /* check for checksum updates when the CAN frame has been modified */
420         if (modidx) {
421                 if (gwj->mod.csumfunc.crc8)
422                         (*gwj->mod.csumfunc.crc8)(cf, &gwj->mod.csum.crc8);
423 
424                 if (gwj->mod.csumfunc.xor)
425                         (*gwj->mod.csumfunc.xor)(cf, &gwj->mod.csum.xor);
426         }
427 
428         /* clear the skb timestamp if not configured the other way */
429         if (!(gwj->flags & CGW_FLAGS_CAN_SRC_TSTAMP))
430                 nskb->tstamp = 0;
431 
432         /* send to netdevice */
433         if (can_send(nskb, gwj->flags & CGW_FLAGS_CAN_ECHO))
434                 gwj->dropped_frames++;
435         else
436                 gwj->handled_frames++;
437 }
438 
439 static inline int cgw_register_filter(struct net *net, struct cgw_job *gwj)
440 {
441         return can_rx_register(net, gwj->src.dev, gwj->ccgw.filter.can_id,
442                                gwj->ccgw.filter.can_mask, can_can_gw_rcv,
443                                gwj, "gw", NULL);
444 }
445 
446 static inline void cgw_unregister_filter(struct net *net, struct cgw_job *gwj)
447 {
448         can_rx_unregister(net, gwj->src.dev, gwj->ccgw.filter.can_id,
449                           gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
450 }
451 
452 static int cgw_notifier(struct notifier_block *nb,
453                         unsigned long msg, void *ptr)
454 {
455         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
456         struct net *net = dev_net(dev);
457 
458         if (dev->type != ARPHRD_CAN)
459                 return NOTIFY_DONE;
460 
461         if (msg == NETDEV_UNREGISTER) {
462 
463                 struct cgw_job *gwj = NULL;
464                 struct hlist_node *nx;
465 
466                 ASSERT_RTNL();
467 
468                 hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
469 
470                         if (gwj->src.dev == dev || gwj->dst.dev == dev) {
471                                 hlist_del(&gwj->list);
472                                 cgw_unregister_filter(net, gwj);
473                                 kmem_cache_free(cgw_cache, gwj);
474                         }
475                 }
476         }
477 
478         return NOTIFY_DONE;
479 }
480 
481 static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
482                        u32 pid, u32 seq, int flags)
483 {
484         struct cgw_frame_mod mb;
485         struct rtcanmsg *rtcan;
486         struct nlmsghdr *nlh;
487 
488         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
489         if (!nlh)
490                 return -EMSGSIZE;
491 
492         rtcan = nlmsg_data(nlh);
493         rtcan->can_family = AF_CAN;
494         rtcan->gwtype = gwj->gwtype;
495         rtcan->flags = gwj->flags;
496 
497         /* add statistics if available */
498 
499         if (gwj->handled_frames) {
500                 if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
501                         goto cancel;
502         }
503 
504         if (gwj->dropped_frames) {
505                 if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
506                         goto cancel;
507         }
508 
509         if (gwj->deleted_frames) {
510                 if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
511                         goto cancel;
512         }
513 
514         /* check non default settings of attributes */
515 
516         if (gwj->limit_hops) {
517                 if (nla_put_u8(skb, CGW_LIM_HOPS, gwj->limit_hops) < 0)
518                         goto cancel;
519         }
520 
521         if (gwj->mod.modtype.and) {
522                 memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
523                 mb.modtype = gwj->mod.modtype.and;
524                 if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
525                         goto cancel;
526         }
527 
528         if (gwj->mod.modtype.or) {
529                 memcpy(&mb.cf, &gwj->mod.modframe.or, sizeof(mb.cf));
530                 mb.modtype = gwj->mod.modtype.or;
531                 if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
532                         goto cancel;
533         }
534 
535         if (gwj->mod.modtype.xor) {
536                 memcpy(&mb.cf, &gwj->mod.modframe.xor, sizeof(mb.cf));
537                 mb.modtype = gwj->mod.modtype.xor;
538                 if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
539                         goto cancel;
540         }
541 
542         if (gwj->mod.modtype.set) {
543                 memcpy(&mb.cf, &gwj->mod.modframe.set, sizeof(mb.cf));
544                 mb.modtype = gwj->mod.modtype.set;
545                 if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
546                         goto cancel;
547         }
548 
549         if (gwj->mod.uid) {
550                 if (nla_put_u32(skb, CGW_MOD_UID, gwj->mod.uid) < 0)
551                         goto cancel;
552         }
553 
554         if (gwj->mod.csumfunc.crc8) {
555                 if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
556                             &gwj->mod.csum.crc8) < 0)
557                         goto cancel;
558         }
559 
560         if (gwj->mod.csumfunc.xor) {
561                 if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
562                             &gwj->mod.csum.xor) < 0)
563                         goto cancel;
564         }
565 
566         if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
567 
568                 if (gwj->ccgw.filter.can_id || gwj->ccgw.filter.can_mask) {
569                         if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
570                                     &gwj->ccgw.filter) < 0)
571                                 goto cancel;
572                 }
573 
574                 if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
575                         goto cancel;
576 
577                 if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
578                         goto cancel;
579         }
580 
581         nlmsg_end(skb, nlh);
582         return 0;
583 
584 cancel:
585         nlmsg_cancel(skb, nlh);
586         return -EMSGSIZE;
587 }
588 
589 /* Dump information about all CAN gateway jobs, in response to RTM_GETROUTE */
590 static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
591 {
592         struct net *net = sock_net(skb->sk);
593         struct cgw_job *gwj = NULL;
594         int idx = 0;
595         int s_idx = cb->args[0];
596 
597         rcu_read_lock();
598         hlist_for_each_entry_rcu(gwj, &net->can.cgw_list, list) {
599                 if (idx < s_idx)
600                         goto cont;
601 
602                 if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).portid,
603                     cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
604                         break;
605 cont:
606                 idx++;
607         }
608         rcu_read_unlock();
609 
610         cb->args[0] = idx;
611 
612         return skb->len;
613 }
614 
615 static const struct nla_policy cgw_policy[CGW_MAX+1] = {
616         [CGW_MOD_AND]   = { .len = sizeof(struct cgw_frame_mod) },
617         [CGW_MOD_OR]    = { .len = sizeof(struct cgw_frame_mod) },
618         [CGW_MOD_XOR]   = { .len = sizeof(struct cgw_frame_mod) },
619         [CGW_MOD_SET]   = { .len = sizeof(struct cgw_frame_mod) },
620         [CGW_CS_XOR]    = { .len = sizeof(struct cgw_csum_xor) },
621         [CGW_CS_CRC8]   = { .len = sizeof(struct cgw_csum_crc8) },
622         [CGW_SRC_IF]    = { .type = NLA_U32 },
623         [CGW_DST_IF]    = { .type = NLA_U32 },
624         [CGW_FILTER]    = { .len = sizeof(struct can_filter) },
625         [CGW_LIM_HOPS]  = { .type = NLA_U8 },
626         [CGW_MOD_UID]   = { .type = NLA_U32 },
627 };
628 
629 /* check for common and gwtype specific attributes */
630 static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
631                           u8 gwtype, void *gwtypeattr, u8 *limhops)
632 {
633         struct nlattr *tb[CGW_MAX+1];
634         struct cgw_frame_mod mb;
635         int modidx = 0;
636         int err = 0;
637 
638         /* initialize modification & checksum data space */
639         memset(mod, 0, sizeof(*mod));
640 
641         err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
642                           cgw_policy, NULL);
643         if (err < 0)
644                 return err;
645 
646         if (tb[CGW_LIM_HOPS]) {
647                 *limhops = nla_get_u8(tb[CGW_LIM_HOPS]);
648 
649                 if (*limhops < 1 || *limhops > max_hops)
650                         return -EINVAL;
651         }
652 
653         /* check for AND/OR/XOR/SET modifications */
654 
655         if (tb[CGW_MOD_AND]) {
656                 nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
657 
658                 canframecpy(&mod->modframe.and, &mb.cf);
659                 mod->modtype.and = mb.modtype;
660 
661                 if (mb.modtype & CGW_MOD_ID)
662                         mod->modfunc[modidx++] = mod_and_id;
663 
664                 if (mb.modtype & CGW_MOD_DLC)
665                         mod->modfunc[modidx++] = mod_and_dlc;
666 
667                 if (mb.modtype & CGW_MOD_DATA)
668                         mod->modfunc[modidx++] = mod_and_data;
669         }
670 
671         if (tb[CGW_MOD_OR]) {
672                 nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
673 
674                 canframecpy(&mod->modframe.or, &mb.cf);
675                 mod->modtype.or = mb.modtype;
676 
677                 if (mb.modtype & CGW_MOD_ID)
678                         mod->modfunc[modidx++] = mod_or_id;
679 
680                 if (mb.modtype & CGW_MOD_DLC)
681                         mod->modfunc[modidx++] = mod_or_dlc;
682 
683                 if (mb.modtype & CGW_MOD_DATA)
684                         mod->modfunc[modidx++] = mod_or_data;
685         }
686 
687         if (tb[CGW_MOD_XOR]) {
688                 nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
689 
690                 canframecpy(&mod->modframe.xor, &mb.cf);
691                 mod->modtype.xor = mb.modtype;
692 
693                 if (mb.modtype & CGW_MOD_ID)
694                         mod->modfunc[modidx++] = mod_xor_id;
695 
696                 if (mb.modtype & CGW_MOD_DLC)
697                         mod->modfunc[modidx++] = mod_xor_dlc;
698 
699                 if (mb.modtype & CGW_MOD_DATA)
700                         mod->modfunc[modidx++] = mod_xor_data;
701         }
702 
703         if (tb[CGW_MOD_SET]) {
704                 nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
705 
706                 canframecpy(&mod->modframe.set, &mb.cf);
707                 mod->modtype.set = mb.modtype;
708 
709                 if (mb.modtype & CGW_MOD_ID)
710                         mod->modfunc[modidx++] = mod_set_id;
711 
712                 if (mb.modtype & CGW_MOD_DLC)
713                         mod->modfunc[modidx++] = mod_set_dlc;
714 
715                 if (mb.modtype & CGW_MOD_DATA)
716                         mod->modfunc[modidx++] = mod_set_data;
717         }
718 
719         /* check for checksum operations after CAN frame modifications */
720         if (modidx) {
721 
722                 if (tb[CGW_CS_CRC8]) {
723                         struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
724 
725                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
726                                                  c->result_idx);
727                         if (err)
728                                 return err;
729 
730                         nla_memcpy(&mod->csum.crc8, tb[CGW_CS_CRC8],
731                                    CGW_CS_CRC8_LEN);
732 
733                         /*
734                          * select dedicated processing function to reduce
735                          * runtime operations in receive hot path.
736                          */
737                         if (c->from_idx < 0 || c->to_idx < 0 ||
738                             c->result_idx < 0)
739                                 mod->csumfunc.crc8 = cgw_csum_crc8_rel;
740                         else if (c->from_idx <= c->to_idx)
741                                 mod->csumfunc.crc8 = cgw_csum_crc8_pos;
742                         else
743                                 mod->csumfunc.crc8 = cgw_csum_crc8_neg;
744                 }
745 
746                 if (tb[CGW_CS_XOR]) {
747                         struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
748 
749                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
750                                                  c->result_idx);
751                         if (err)
752                                 return err;
753 
754                         nla_memcpy(&mod->csum.xor, tb[CGW_CS_XOR],
755                                    CGW_CS_XOR_LEN);
756 
757                         /*
758                          * select dedicated processing function to reduce
759                          * runtime operations in receive hot path.
760                          */
761                         if (c->from_idx < 0 || c->to_idx < 0 ||
762                             c->result_idx < 0)
763                                 mod->csumfunc.xor = cgw_csum_xor_rel;
764                         else if (c->from_idx <= c->to_idx)
765                                 mod->csumfunc.xor = cgw_csum_xor_pos;
766                         else
767                                 mod->csumfunc.xor = cgw_csum_xor_neg;
768                 }
769 
770                 if (tb[CGW_MOD_UID]) {
771                         nla_memcpy(&mod->uid, tb[CGW_MOD_UID], sizeof(u32));
772                 }
773         }
774 
775         if (gwtype == CGW_TYPE_CAN_CAN) {
776 
777                 /* check CGW_TYPE_CAN_CAN specific attributes */
778 
779                 struct can_can_gw *ccgw = (struct can_can_gw *)gwtypeattr;
780                 memset(ccgw, 0, sizeof(*ccgw));
781 
782                 /* check for can_filter in attributes */
783                 if (tb[CGW_FILTER])
784                         nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
785                                    sizeof(struct can_filter));
786 
787                 err = -ENODEV;
788 
789                 /* specifying two interfaces is mandatory */
790                 if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
791                         return err;
792 
793                 ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
794                 ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
795 
796                 /* both indices set to 0 for flushing all routing entries */
797                 if (!ccgw->src_idx && !ccgw->dst_idx)
798                         return 0;
799 
800                 /* only one index set to 0 is an error */
801                 if (!ccgw->src_idx || !ccgw->dst_idx)
802                         return err;
803         }
804 
805         /* add the checks for other gwtypes here */
806 
807         return 0;
808 }
809 
810 static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh,
811                           struct netlink_ext_ack *extack)
812 {
813         struct net *net = sock_net(skb->sk);
814         struct rtcanmsg *r;
815         struct cgw_job *gwj;
816         struct cf_mod mod;
817         struct can_can_gw ccgw;
818         u8 limhops = 0;
819         int err = 0;
820 
821         if (!netlink_capable(skb, CAP_NET_ADMIN))
822                 return -EPERM;
823 
824         if (nlmsg_len(nlh) < sizeof(*r))
825                 return -EINVAL;
826 
827         r = nlmsg_data(nlh);
828         if (r->can_family != AF_CAN)
829                 return -EPFNOSUPPORT;
830 
831         /* so far we only support CAN -> CAN routings */
832         if (r->gwtype != CGW_TYPE_CAN_CAN)
833                 return -EINVAL;
834 
835         err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
836         if (err < 0)
837                 return err;
838 
839         if (mod.uid) {
840 
841                 ASSERT_RTNL();
842 
843                 /* check for updating an existing job with identical uid */
844                 hlist_for_each_entry(gwj, &net->can.cgw_list, list) {
845 
846                         if (gwj->mod.uid != mod.uid)
847                                 continue;
848 
849                         /* interfaces & filters must be identical */
850                         if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
851                                 return -EINVAL;
852 
853                         /* update modifications with disabled softirq & quit */
854                         local_bh_disable();
855                         memcpy(&gwj->mod, &mod, sizeof(mod));
856                         local_bh_enable();
857                         return 0;
858                 }
859         }
860 
861         /* ifindex == 0 is not allowed for job creation */
862         if (!ccgw.src_idx || !ccgw.dst_idx)
863                 return -ENODEV;
864 
865         gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
866         if (!gwj)
867                 return -ENOMEM;
868 
869         gwj->handled_frames = 0;
870         gwj->dropped_frames = 0;
871         gwj->deleted_frames = 0;
872         gwj->flags = r->flags;
873         gwj->gwtype = r->gwtype;
874         gwj->limit_hops = limhops;
875 
876         /* insert already parsed information */
877         memcpy(&gwj->mod, &mod, sizeof(mod));
878         memcpy(&gwj->ccgw, &ccgw, sizeof(ccgw));
879 
880         err = -ENODEV;
881 
882         gwj->src.dev = __dev_get_by_index(net, gwj->ccgw.src_idx);
883 
884         if (!gwj->src.dev)
885                 goto out;
886 
887         if (gwj->src.dev->type != ARPHRD_CAN)
888                 goto out;
889 
890         gwj->dst.dev = __dev_get_by_index(net, gwj->ccgw.dst_idx);
891 
892         if (!gwj->dst.dev)
893                 goto out;
894 
895         if (gwj->dst.dev->type != ARPHRD_CAN)
896                 goto out;
897 
898         ASSERT_RTNL();
899 
900         err = cgw_register_filter(net, gwj);
901         if (!err)
902                 hlist_add_head_rcu(&gwj->list, &net->can.cgw_list);
903 out:
904         if (err)
905                 kmem_cache_free(cgw_cache, gwj);
906 
907         return err;
908 }
909 
910 static void cgw_remove_all_jobs(struct net *net)
911 {
912         struct cgw_job *gwj = NULL;
913         struct hlist_node *nx;
914 
915         ASSERT_RTNL();
916 
917         hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
918                 hlist_del(&gwj->list);
919                 cgw_unregister_filter(net, gwj);
920                 kmem_cache_free(cgw_cache, gwj);
921         }
922 }
923 
924 static int cgw_remove_job(struct sk_buff *skb, struct nlmsghdr *nlh,
925                           struct netlink_ext_ack *extack)
926 {
927         struct net *net = sock_net(skb->sk);
928         struct cgw_job *gwj = NULL;
929         struct hlist_node *nx;
930         struct rtcanmsg *r;
931         struct cf_mod mod;
932         struct can_can_gw ccgw;
933         u8 limhops = 0;
934         int err = 0;
935 
936         if (!netlink_capable(skb, CAP_NET_ADMIN))
937                 return -EPERM;
938 
939         if (nlmsg_len(nlh) < sizeof(*r))
940                 return -EINVAL;
941 
942         r = nlmsg_data(nlh);
943         if (r->can_family != AF_CAN)
944                 return -EPFNOSUPPORT;
945 
946         /* so far we only support CAN -> CAN routings */
947         if (r->gwtype != CGW_TYPE_CAN_CAN)
948                 return -EINVAL;
949 
950         err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw, &limhops);
951         if (err < 0)
952                 return err;
953 
954         /* two interface indices both set to 0 => remove all entries */
955         if (!ccgw.src_idx && !ccgw.dst_idx) {
956                 cgw_remove_all_jobs(net);
957                 return 0;
958         }
959 
960         err = -EINVAL;
961 
962         ASSERT_RTNL();
963 
964         /* remove only the first matching entry */
965         hlist_for_each_entry_safe(gwj, nx, &net->can.cgw_list, list) {
966 
967                 if (gwj->flags != r->flags)
968                         continue;
969 
970                 if (gwj->limit_hops != limhops)
971                         continue;
972 
973                 /* we have a match when uid is enabled and identical */
974                 if (gwj->mod.uid || mod.uid) {
975                         if (gwj->mod.uid != mod.uid)
976                                 continue;
977                 } else {
978                         /* no uid => check for identical modifications */
979                         if (memcmp(&gwj->mod, &mod, sizeof(mod)))
980                                 continue;
981                 }
982 
983                 /* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
984                 if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
985                         continue;
986 
987                 hlist_del(&gwj->list);
988                 cgw_unregister_filter(net, gwj);
989                 kmem_cache_free(cgw_cache, gwj);
990                 err = 0;
991                 break;
992         }
993 
994         return err;
995 }
996 
997 static int __net_init cangw_pernet_init(struct net *net)
998 {
999         INIT_HLIST_HEAD(&net->can.cgw_list);
1000         return 0;
1001 }
1002 
1003 static void __net_exit cangw_pernet_exit(struct net *net)
1004 {
1005         rtnl_lock();
1006         cgw_remove_all_jobs(net);
1007         rtnl_unlock();
1008 }
1009 
1010 static struct pernet_operations cangw_pernet_ops = {
1011         .init = cangw_pernet_init,
1012         .exit = cangw_pernet_exit,
1013 };
1014 
1015 static __init int cgw_module_init(void)
1016 {
1017         int ret;
1018 
1019         /* sanitize given module parameter */
1020         max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
1021 
1022         pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
1023                 max_hops);
1024 
1025         register_pernet_subsys(&cangw_pernet_ops);
1026         cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
1027                                       0, 0, NULL);
1028 
1029         if (!cgw_cache)
1030                 return -ENOMEM;
1031 
1032         /* set notifier */
1033         notifier.notifier_call = cgw_notifier;
1034         register_netdevice_notifier(&notifier);
1035 
1036         ret = rtnl_register_module(THIS_MODULE, PF_CAN, RTM_GETROUTE,
1037                                    NULL, cgw_dump_jobs, 0);
1038         if (ret) {
1039                 unregister_netdevice_notifier(&notifier);
1040                 kmem_cache_destroy(cgw_cache);
1041                 return -ENOBUFS;
1042         }
1043 
1044         /* Only the first call to rtnl_register_module can fail */
1045         rtnl_register_module(THIS_MODULE, PF_CAN, RTM_NEWROUTE,
1046                              cgw_create_job, NULL, 0);
1047         rtnl_register_module(THIS_MODULE, PF_CAN, RTM_DELROUTE,
1048                              cgw_remove_job, NULL, 0);
1049 
1050         return 0;
1051 }
1052 
1053 static __exit void cgw_module_exit(void)
1054 {
1055         rtnl_unregister_all(PF_CAN);
1056 
1057         unregister_netdevice_notifier(&notifier);
1058 
1059         unregister_pernet_subsys(&cangw_pernet_ops);
1060         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1061 
1062         kmem_cache_destroy(cgw_cache);
1063 }
1064 
1065 module_init(cgw_module_init);
1066 module_exit(cgw_module_exit);
1067 

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