net/can/gw.c

   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         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/unsued 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         nskb->dev = gwj->dst.dev;
 406
 407         /* pointer to modifiable CAN frame */
 408         cf = (struct can_frame *)nskb->data;
 409
 410         /* perform preprocessed modification functions if there are any */
 411         while (modidx < MAX_MODFUNCTIONS && gwj->mod.modfunc[modidx])
 412                 (*gwj->mod.modfunc[modidx++])(cf, &gwj->mod);
 413
 414         /* check for checksum updates when the CAN frame has been modified */
 415         if (modidx) {
 416                 if (gwj->mod.csumfunc.crc8)
 417                         (*gwj->mod.csumfunc.crc8)(cf, &gwj->mod.csum.crc8);
 418
 419                 if (gwj->mod.csumfunc.xor)
 420                         (*gwj->mod.csumfunc.xor)(cf, &gwj->mod.csum.xor);
 421         }
 422
 423         /* clear the skb timestamp if not configured the other way */
 424         if (!(gwj->flags & CGW_FLAGS_CAN_SRC_TSTAMP))
 425                 nskb->tstamp.tv64 = 0;
 426
 427         /* send to netdevice */
 428         if (can_send(nskb, gwj->flags & CGW_FLAGS_CAN_ECHO))
 429                 gwj->dropped_frames++;
 430         else
 431                 gwj->handled_frames++;
 432 }
 433
 434 static inline int cgw_register_filter(struct cgw_job *gwj)
 435 {
 436         return can_rx_register(gwj->src.dev, gwj->ccgw.filter.can_id,
 437                                gwj->ccgw.filter.can_mask, can_can_gw_rcv,
 438                                gwj, "gw");
 439 }
 440
 441 static inline void cgw_unregister_filter(struct cgw_job *gwj)
 442 {
 443         can_rx_unregister(gwj->src.dev, gwj->ccgw.filter.can_id,
 444                           gwj->ccgw.filter.can_mask, can_can_gw_rcv, gwj);
 445 }
 446
 447 static int cgw_notifier(struct notifier_block *nb,
 448                         unsigned long msg, void *data)
 449 {
 450         struct net_device *dev = (struct net_device *)data;
 451
 452         if (!net_eq(dev_net(dev), &init_net))
 453                 return NOTIFY_DONE;
 454         if (dev->type != ARPHRD_CAN)
 455                 return NOTIFY_DONE;
 456
 457         if (msg == NETDEV_UNREGISTER) {
 458
 459                 struct cgw_job *gwj = NULL;
 460                 struct hlist_node *nx;
 461
 462                 ASSERT_RTNL();
 463
 464                 hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
 465
 466                         if (gwj->src.dev == dev || gwj->dst.dev == dev) {
 467                                 hlist_del(&gwj->list);
 468                                 cgw_unregister_filter(gwj);
 469                                 kmem_cache_free(cgw_cache, gwj);
 470                         }
 471                 }
 472         }
 473
 474         return NOTIFY_DONE;
 475 }
 476
 477 static int cgw_put_job(struct sk_buff *skb, struct cgw_job *gwj, int type,
 478                        u32 pid, u32 seq, int flags)
 479 {
 480         struct cgw_frame_mod mb;
 481         struct rtcanmsg *rtcan;
 482         struct nlmsghdr *nlh;
 483
 484         nlh = nlmsg_put(skb, pid, seq, type, sizeof(*rtcan), flags);
 485         if (!nlh)
 486                 return -EMSGSIZE;
 487
 488         rtcan = nlmsg_data(nlh);
 489         rtcan->can_family = AF_CAN;
 490         rtcan->gwtype = gwj->gwtype;
 491         rtcan->flags = gwj->flags;
 492
 493         /* add statistics if available */
 494
 495         if (gwj->handled_frames) {
 496                 if (nla_put_u32(skb, CGW_HANDLED, gwj->handled_frames) < 0)
 497                         goto cancel;
 498         }
 499
 500         if (gwj->dropped_frames) {
 501                 if (nla_put_u32(skb, CGW_DROPPED, gwj->dropped_frames) < 0)
 502                         goto cancel;
 503         }
 504
 505         if (gwj->deleted_frames) {
 506                 if (nla_put_u32(skb, CGW_DELETED, gwj->deleted_frames) < 0)
 507                         goto cancel;
 508         }
 509
 510         /* check non default settings of attributes */
 511
 512         if (gwj->mod.modtype.and) {
 513                 memcpy(&mb.cf, &gwj->mod.modframe.and, sizeof(mb.cf));
 514                 mb.modtype = gwj->mod.modtype.and;
 515                 if (nla_put(skb, CGW_MOD_AND, sizeof(mb), &mb) < 0)
 516                         goto cancel;
 517         }
 518
 519         if (gwj->mod.modtype.or) {
 520                 memcpy(&mb.cf, &gwj->mod.modframe.or, sizeof(mb.cf));
 521                 mb.modtype = gwj->mod.modtype.or;
 522                 if (nla_put(skb, CGW_MOD_OR, sizeof(mb), &mb) < 0)
 523                         goto cancel;
 524         }
 525
 526         if (gwj->mod.modtype.xor) {
 527                 memcpy(&mb.cf, &gwj->mod.modframe.xor, sizeof(mb.cf));
 528                 mb.modtype = gwj->mod.modtype.xor;
 529                 if (nla_put(skb, CGW_MOD_XOR, sizeof(mb), &mb) < 0)
 530                         goto cancel;
 531         }
 532
 533         if (gwj->mod.modtype.set) {
 534                 memcpy(&mb.cf, &gwj->mod.modframe.set, sizeof(mb.cf));
 535                 mb.modtype = gwj->mod.modtype.set;
 536                 if (nla_put(skb, CGW_MOD_SET, sizeof(mb), &mb) < 0)
 537                         goto cancel;
 538         }
 539
 540         if (gwj->mod.csumfunc.crc8) {
 541                 if (nla_put(skb, CGW_CS_CRC8, CGW_CS_CRC8_LEN,
 542                             &gwj->mod.csum.crc8) < 0)
 543                         goto cancel;
 544         }
 545
 546         if (gwj->mod.csumfunc.xor) {
 547                 if (nla_put(skb, CGW_CS_XOR, CGW_CS_XOR_LEN,
 548                             &gwj->mod.csum.xor) < 0)
 549                         goto cancel;
 550         }
 551
 552         if (gwj->gwtype == CGW_TYPE_CAN_CAN) {
 553
 554                 if (gwj->ccgw.filter.can_id || gwj->ccgw.filter.can_mask) {
 555                         if (nla_put(skb, CGW_FILTER, sizeof(struct can_filter),
 556                                     &gwj->ccgw.filter) < 0)
 557                                 goto cancel;
 558                 }
 559
 560                 if (nla_put_u32(skb, CGW_SRC_IF, gwj->ccgw.src_idx) < 0)
 561                         goto cancel;
 562
 563                 if (nla_put_u32(skb, CGW_DST_IF, gwj->ccgw.dst_idx) < 0)
 564                         goto cancel;
 565         }
 566
 567         return nlmsg_end(skb, nlh);
 568
 569 cancel:
 570         nlmsg_cancel(skb, nlh);
 571         return -EMSGSIZE;
 572 }
 573
 574 /* Dump information about all CAN gateway jobs, in response to RTM_GETROUTE */
 575 static int cgw_dump_jobs(struct sk_buff *skb, struct netlink_callback *cb)
 576 {
 577         struct cgw_job *gwj = NULL;
 578         int idx = 0;
 579         int s_idx = cb->args[0];
 580
 581         rcu_read_lock();
 582         hlist_for_each_entry_rcu(gwj, &cgw_list, list) {
 583                 if (idx < s_idx)
 584                         goto cont;
 585
 586                 if (cgw_put_job(skb, gwj, RTM_NEWROUTE, NETLINK_CB(cb->skb).portid,
 587                     cb->nlh->nlmsg_seq, NLM_F_MULTI) < 0)
 588                         break;
 589 cont:
 590                 idx++;
 591         }
 592         rcu_read_unlock();
 593
 594         cb->args[0] = idx;
 595
 596         return skb->len;
 597 }
 598
 599 static const struct nla_policy cgw_policy[CGW_MAX+1] = {
 600         [CGW_MOD_AND]   = { .len = sizeof(struct cgw_frame_mod) },
 601         [CGW_MOD_OR]    = { .len = sizeof(struct cgw_frame_mod) },
 602         [CGW_MOD_XOR]   = { .len = sizeof(struct cgw_frame_mod) },
 603         [CGW_MOD_SET]   = { .len = sizeof(struct cgw_frame_mod) },
 604         [CGW_CS_XOR]    = { .len = sizeof(struct cgw_csum_xor) },
 605         [CGW_CS_CRC8]   = { .len = sizeof(struct cgw_csum_crc8) },
 606         [CGW_SRC_IF]    = { .type = NLA_U32 },
 607         [CGW_DST_IF]    = { .type = NLA_U32 },
 608         [CGW_FILTER]    = { .len = sizeof(struct can_filter) },
 609 };
 610
 611 /* check for common and gwtype specific attributes */
 612 static int cgw_parse_attr(struct nlmsghdr *nlh, struct cf_mod *mod,
 613                           u8 gwtype, void *gwtypeattr)
 614 {
 615         struct nlattr *tb[CGW_MAX+1];
 616         struct cgw_frame_mod mb;
 617         int modidx = 0;
 618         int err = 0;
 619
 620         /* initialize modification & checksum data space */
 621         memset(mod, 0, sizeof(*mod));
 622
 623         err = nlmsg_parse(nlh, sizeof(struct rtcanmsg), tb, CGW_MAX,
 624                           cgw_policy);
 625         if (err < 0)
 626                 return err;
 627
 628         /* check for AND/OR/XOR/SET modifications */
 629
 630         if (tb[CGW_MOD_AND]) {
 631                 nla_memcpy(&mb, tb[CGW_MOD_AND], CGW_MODATTR_LEN);
 632
 633                 canframecpy(&mod->modframe.and, &mb.cf);
 634                 mod->modtype.and = mb.modtype;
 635
 636                 if (mb.modtype & CGW_MOD_ID)
 637                         mod->modfunc[modidx++] = mod_and_id;
 638
 639                 if (mb.modtype & CGW_MOD_DLC)
 640                         mod->modfunc[modidx++] = mod_and_dlc;
 641
 642                 if (mb.modtype & CGW_MOD_DATA)
 643                         mod->modfunc[modidx++] = mod_and_data;
 644         }
 645
 646         if (tb[CGW_MOD_OR]) {
 647                 nla_memcpy(&mb, tb[CGW_MOD_OR], CGW_MODATTR_LEN);
 648
 649                 canframecpy(&mod->modframe.or, &mb.cf);
 650                 mod->modtype.or = mb.modtype;
 651
 652                 if (mb.modtype & CGW_MOD_ID)
 653                         mod->modfunc[modidx++] = mod_or_id;
 654
 655                 if (mb.modtype & CGW_MOD_DLC)
 656                         mod->modfunc[modidx++] = mod_or_dlc;
 657
 658                 if (mb.modtype & CGW_MOD_DATA)
 659                         mod->modfunc[modidx++] = mod_or_data;
 660         }
 661
 662         if (tb[CGW_MOD_XOR]) {
 663                 nla_memcpy(&mb, tb[CGW_MOD_XOR], CGW_MODATTR_LEN);
 664
 665                 canframecpy(&mod->modframe.xor, &mb.cf);
 666                 mod->modtype.xor = mb.modtype;
 667
 668                 if (mb.modtype & CGW_MOD_ID)
 669                         mod->modfunc[modidx++] = mod_xor_id;
 670
 671                 if (mb.modtype & CGW_MOD_DLC)
 672                         mod->modfunc[modidx++] = mod_xor_dlc;
 673
 674                 if (mb.modtype & CGW_MOD_DATA)
 675                         mod->modfunc[modidx++] = mod_xor_data;
 676         }
 677
 678         if (tb[CGW_MOD_SET]) {
 679                 nla_memcpy(&mb, tb[CGW_MOD_SET], CGW_MODATTR_LEN);
 680
 681                 canframecpy(&mod->modframe.set, &mb.cf);
 682                 mod->modtype.set = mb.modtype;
 683
 684                 if (mb.modtype & CGW_MOD_ID)
 685                         mod->modfunc[modidx++] = mod_set_id;
 686
 687                 if (mb.modtype & CGW_MOD_DLC)
 688                         mod->modfunc[modidx++] = mod_set_dlc;
 689
 690                 if (mb.modtype & CGW_MOD_DATA)
 691                         mod->modfunc[modidx++] = mod_set_data;
 692         }
 693
 694         /* check for checksum operations after CAN frame modifications */
 695         if (modidx) {
 696
 697                 if (tb[CGW_CS_CRC8]) {
 698                         struct cgw_csum_crc8 *c = nla_data(tb[CGW_CS_CRC8]);
 699
 700                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
 701                                                  c->result_idx);
 702                         if (err)
 703                                 return err;
 704
 705                         nla_memcpy(&mod->csum.crc8, tb[CGW_CS_CRC8],
 706                                    CGW_CS_CRC8_LEN);
 707
 708                         /*
 709                          * select dedicated processing function to reduce
 710                          * runtime operations in receive hot path.
 711                          */
 712                         if (c->from_idx < 0 || c->to_idx < 0 ||
 713                             c->result_idx < 0)
 714                                 mod->csumfunc.crc8 = cgw_csum_crc8_rel;
 715                         else if (c->from_idx <= c->to_idx)
 716                                 mod->csumfunc.crc8 = cgw_csum_crc8_pos;
 717                         else
 718                                 mod->csumfunc.crc8 = cgw_csum_crc8_neg;
 719                 }
 720
 721                 if (tb[CGW_CS_XOR]) {
 722                         struct cgw_csum_xor *c = nla_data(tb[CGW_CS_XOR]);
 723
 724                         err = cgw_chk_csum_parms(c->from_idx, c->to_idx,
 725                                                  c->result_idx);
 726                         if (err)
 727                                 return err;
 728
 729                         nla_memcpy(&mod->csum.xor, tb[CGW_CS_XOR],
 730                                    CGW_CS_XOR_LEN);
 731
 732                         /*
 733                          * select dedicated processing function to reduce
 734                          * runtime operations in receive hot path.
 735                          */
 736                         if (c->from_idx < 0 || c->to_idx < 0 ||
 737                             c->result_idx < 0)
 738                                 mod->csumfunc.xor = cgw_csum_xor_rel;
 739                         else if (c->from_idx <= c->to_idx)
 740                                 mod->csumfunc.xor = cgw_csum_xor_pos;
 741                         else
 742                                 mod->csumfunc.xor = cgw_csum_xor_neg;
 743                 }
 744         }
 745
 746         if (gwtype == CGW_TYPE_CAN_CAN) {
 747
 748                 /* check CGW_TYPE_CAN_CAN specific attributes */
 749
 750                 struct can_can_gw *ccgw = (struct can_can_gw *)gwtypeattr;
 751                 memset(ccgw, 0, sizeof(*ccgw));
 752
 753                 /* check for can_filter in attributes */
 754                 if (tb[CGW_FILTER])
 755                         nla_memcpy(&ccgw->filter, tb[CGW_FILTER],
 756                                    sizeof(struct can_filter));
 757
 758                 err = -ENODEV;
 759
 760                 /* specifying two interfaces is mandatory */
 761                 if (!tb[CGW_SRC_IF] || !tb[CGW_DST_IF])
 762                         return err;
 763
 764                 ccgw->src_idx = nla_get_u32(tb[CGW_SRC_IF]);
 765                 ccgw->dst_idx = nla_get_u32(tb[CGW_DST_IF]);
 766
 767                 /* both indices set to 0 for flushing all routing entries */
 768                 if (!ccgw->src_idx && !ccgw->dst_idx)
 769                         return 0;
 770
 771                 /* only one index set to 0 is an error */
 772                 if (!ccgw->src_idx || !ccgw->dst_idx)
 773                         return err;
 774         }
 775
 776         /* add the checks for other gwtypes here */
 777
 778         return 0;
 779 }
 780
 781 static int cgw_create_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
 782 {
 783         struct rtcanmsg *r;
 784         struct cgw_job *gwj;
 785         int err = 0;
 786
 787         if (!netlink_capable(skb, CAP_NET_ADMIN))
 788                 return -EPERM;
 789
 790         if (nlmsg_len(nlh) < sizeof(*r))
 791                 return -EINVAL;
 792
 793         r = nlmsg_data(nlh);
 794         if (r->can_family != AF_CAN)
 795                 return -EPFNOSUPPORT;
 796
 797         /* so far we only support CAN -> CAN routings */
 798         if (r->gwtype != CGW_TYPE_CAN_CAN)
 799                 return -EINVAL;
 800
 801         gwj = kmem_cache_alloc(cgw_cache, GFP_KERNEL);
 802         if (!gwj)
 803                 return -ENOMEM;
 804
 805         gwj->handled_frames = 0;
 806         gwj->dropped_frames = 0;
 807         gwj->deleted_frames = 0;
 808         gwj->flags = r->flags;
 809         gwj->gwtype = r->gwtype;
 810
 811         err = cgw_parse_attr(nlh, &gwj->mod, CGW_TYPE_CAN_CAN, &gwj->ccgw);
 812         if (err < 0)
 813                 goto out;
 814
 815         err = -ENODEV;
 816
 817         /* ifindex == 0 is not allowed for job creation */
 818         if (!gwj->ccgw.src_idx || !gwj->ccgw.dst_idx)
 819                 goto out;
 820
 821         gwj->src.dev = dev_get_by_index(&init_net, gwj->ccgw.src_idx);
 822
 823         if (!gwj->src.dev)
 824                 goto out;
 825
 826         /* check for CAN netdev not using header_ops - see gw_rcv() */
 827         if (gwj->src.dev->type != ARPHRD_CAN || gwj->src.dev->header_ops)
 828                 goto put_src_out;
 829
 830         gwj->dst.dev = dev_get_by_index(&init_net, gwj->ccgw.dst_idx);
 831
 832         if (!gwj->dst.dev)
 833                 goto put_src_out;
 834
 835         /* check for CAN netdev not using header_ops - see gw_rcv() */
 836         if (gwj->dst.dev->type != ARPHRD_CAN || gwj->dst.dev->header_ops)
 837                 goto put_src_dst_out;
 838
 839         ASSERT_RTNL();
 840
 841         err = cgw_register_filter(gwj);
 842         if (!err)
 843                 hlist_add_head_rcu(&gwj->list, &cgw_list);
 844
 845 put_src_dst_out:
 846         dev_put(gwj->dst.dev);
 847 put_src_out:
 848         dev_put(gwj->src.dev);
 849 out:
 850         if (err)
 851                 kmem_cache_free(cgw_cache, gwj);
 852
 853         return err;
 854 }
 855
 856 static void cgw_remove_all_jobs(void)
 857 {
 858         struct cgw_job *gwj = NULL;
 859         struct hlist_node *nx;
 860
 861         ASSERT_RTNL();
 862
 863         hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
 864                 hlist_del(&gwj->list);
 865                 cgw_unregister_filter(gwj);
 866                 kmem_cache_free(cgw_cache, gwj);
 867         }
 868 }
 869
 870 static int cgw_remove_job(struct sk_buff *skb,  struct nlmsghdr *nlh)
 871 {
 872         struct cgw_job *gwj = NULL;
 873         struct hlist_node *nx;
 874         struct rtcanmsg *r;
 875         struct cf_mod mod;
 876         struct can_can_gw ccgw;
 877         int err = 0;
 878
 879         if (!netlink_capable(skb, CAP_NET_ADMIN))
 880                 return -EPERM;
 881
 882         if (nlmsg_len(nlh) < sizeof(*r))
 883                 return -EINVAL;
 884
 885         r = nlmsg_data(nlh);
 886         if (r->can_family != AF_CAN)
 887                 return -EPFNOSUPPORT;
 888
 889         /* so far we only support CAN -> CAN routings */
 890         if (r->gwtype != CGW_TYPE_CAN_CAN)
 891                 return -EINVAL;
 892
 893         err = cgw_parse_attr(nlh, &mod, CGW_TYPE_CAN_CAN, &ccgw);
 894         if (err < 0)
 895                 return err;
 896
 897         /* two interface indices both set to 0 => remove all entries */
 898         if (!ccgw.src_idx && !ccgw.dst_idx) {
 899                 cgw_remove_all_jobs();
 900                 return 0;
 901         }
 902
 903         err = -EINVAL;
 904
 905         ASSERT_RTNL();
 906
 907         /* remove only the first matching entry */
 908         hlist_for_each_entry_safe(gwj, nx, &cgw_list, list) {
 909
 910                 if (gwj->flags != r->flags)
 911                         continue;
 912
 913                 if (memcmp(&gwj->mod, &mod, sizeof(mod)))
 914                         continue;
 915
 916                 /* if (r->gwtype == CGW_TYPE_CAN_CAN) - is made sure here */
 917                 if (memcmp(&gwj->ccgw, &ccgw, sizeof(ccgw)))
 918                         continue;
 919
 920                 hlist_del(&gwj->list);
 921                 cgw_unregister_filter(gwj);
 922                 kmem_cache_free(cgw_cache, gwj);
 923                 err = 0;
 924                 break;
 925         }
 926
 927         return err;
 928 }
 929
 930 static __init int cgw_module_init(void)
 931 {
 932         /* sanitize given module parameter */
 933         max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
 934
 935         pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
 936                 max_hops);
 937
 938         cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
 939                                       0, 0, NULL);
 940
 941         if (!cgw_cache)
 942                 return -ENOMEM;
 943
 944         /* set notifier */
 945         notifier.notifier_call = cgw_notifier;
 946         register_netdevice_notifier(&notifier);
 947
 948         if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, NULL)) {
 949                 unregister_netdevice_notifier(&notifier);
 950                 kmem_cache_destroy(cgw_cache);
 951                 return -ENOBUFS;
 952         }
 953
 954         /* Only the first call to __rtnl_register can fail */
 955         __rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, NULL);
 956         __rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, NULL);
 957
 958         return 0;
 959 }
 960
 961 static __exit void cgw_module_exit(void)
 962 {
 963         rtnl_unregister_all(PF_CAN);
 964
 965         unregister_netdevice_notifier(&notifier);
 966
 967         rtnl_lock();
 968         cgw_remove_all_jobs();
 969         rtnl_unlock();
 970
 971         rcu_barrier(); /* Wait for completion of call_rcu()'s */
 972
 973         kmem_cache_destroy(cgw_cache);
 974 }
 975
 976 module_init(cgw_module_init);
 977 module_exit(cgw_module_exit);