net/can/gw.c

   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, 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 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         /* sanitize given module parameter */
1018         max_hops = clamp_t(unsigned int, max_hops, CGW_MIN_HOPS, CGW_MAX_HOPS);
1019
1020         pr_info("can: netlink gateway (rev " CAN_GW_VERSION ") max_hops=%d\n",
1021                 max_hops);
1022
1023         register_pernet_subsys(&cangw_pernet_ops);
1024         cgw_cache = kmem_cache_create("can_gw", sizeof(struct cgw_job),
1025                                       0, 0, NULL);
1026
1027         if (!cgw_cache)
1028                 return -ENOMEM;
1029
1030         /* set notifier */
1031         notifier.notifier_call = cgw_notifier;
1032         register_netdevice_notifier(&notifier);
1033
1034         if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, 0)) {
1035                 unregister_netdevice_notifier(&notifier);
1036                 kmem_cache_destroy(cgw_cache);
1037                 return -ENOBUFS;
1038         }
1039
1040         /* Only the first call to __rtnl_register can fail */
1041         __rtnl_register(PF_CAN, RTM_NEWROUTE, cgw_create_job, NULL, 0);
1042         __rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, 0);
1043
1044         return 0;
1045 }
1046
1047 static __exit void cgw_module_exit(void)
1048 {
1049         rtnl_unregister_all(PF_CAN);
1050
1051         unregister_netdevice_notifier(&notifier);
1052
1053         unregister_pernet_subsys(&cangw_pernet_ops);
1054         rcu_barrier(); /* Wait for completion of call_rcu()'s */
1055
1056         kmem_cache_destroy(cgw_cache);
1057 }
1058
1059 module_init(cgw_module_init);
1060 module_exit(cgw_module_exit);