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(¬ifier); 1033 1034 if (__rtnl_register(PF_CAN, RTM_GETROUTE, NULL, cgw_dump_jobs, NULL)) { 1035 unregister_netdevice_notifier(¬ifier); 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, NULL); 1042 __rtnl_register(PF_CAN, RTM_DELROUTE, cgw_remove_job, NULL, NULL); 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(¬ifier); 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); 1061