1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (C) 2009-2020 B.A.T.M.A.N. contributors: 3 * 4 * Marek Lindner 5 */ 6 7 #include "gateway_client.h" 8 #include "main.h" 9 10 #include <linux/atomic.h> 11 #include <linux/byteorder/generic.h> 12 #include <linux/errno.h> 13 #include <linux/etherdevice.h> 14 #include <linux/gfp.h> 15 #include <linux/if_ether.h> 16 #include <linux/if_vlan.h> 17 #include <linux/in.h> 18 #include <linux/ip.h> 19 #include <linux/ipv6.h> 20 #include <linux/kernel.h> 21 #include <linux/kref.h> 22 #include <linux/list.h> 23 #include <linux/lockdep.h> 24 #include <linux/netdevice.h> 25 #include <linux/netlink.h> 26 #include <linux/rculist.h> 27 #include <linux/rcupdate.h> 28 #include <linux/skbuff.h> 29 #include <linux/slab.h> 30 #include <linux/spinlock.h> 31 #include <linux/stddef.h> 32 #include <linux/udp.h> 33 #include <net/sock.h> 34 #include <uapi/linux/batadv_packet.h> 35 #include <uapi/linux/batman_adv.h> 36 37 #include "hard-interface.h" 38 #include "log.h" 39 #include "netlink.h" 40 #include "originator.h" 41 #include "routing.h" 42 #include "soft-interface.h" 43 #include "translation-table.h" 44 45 /* These are the offsets of the "hw type" and "hw address length" in the dhcp 46 * packet starting at the beginning of the dhcp header 47 */ 48 #define BATADV_DHCP_HTYPE_OFFSET 1 49 #define BATADV_DHCP_HLEN_OFFSET 2 50 /* Value of htype representing Ethernet */ 51 #define BATADV_DHCP_HTYPE_ETHERNET 0x01 52 /* This is the offset of the "chaddr" field in the dhcp packet starting at the 53 * beginning of the dhcp header 54 */ 55 #define BATADV_DHCP_CHADDR_OFFSET 28 56 57 /** 58 * batadv_gw_node_release() - release gw_node from lists and queue for free 59 * after rcu grace period 60 * @ref: kref pointer of the gw_node 61 */ 62 static void batadv_gw_node_release(struct kref *ref) 63 { 64 struct batadv_gw_node *gw_node; 65 66 gw_node = container_of(ref, struct batadv_gw_node, refcount); 67 68 batadv_orig_node_put(gw_node->orig_node); 69 kfree_rcu(gw_node, rcu); 70 } 71 72 /** 73 * batadv_gw_node_put() - decrement the gw_node refcounter and possibly release 74 * it 75 * @gw_node: gateway node to free 76 */ 77 void batadv_gw_node_put(struct batadv_gw_node *gw_node) 78 { 79 kref_put(&gw_node->refcount, batadv_gw_node_release); 80 } 81 82 /** 83 * batadv_gw_get_selected_gw_node() - Get currently selected gateway 84 * @bat_priv: the bat priv with all the soft interface information 85 * 86 * Return: selected gateway (with increased refcnt), NULL on errors 87 */ 88 struct batadv_gw_node * 89 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) 90 { 91 struct batadv_gw_node *gw_node; 92 93 rcu_read_lock(); 94 gw_node = rcu_dereference(bat_priv->gw.curr_gw); 95 if (!gw_node) 96 goto out; 97 98 if (!kref_get_unless_zero(&gw_node->refcount)) 99 gw_node = NULL; 100 101 out: 102 rcu_read_unlock(); 103 return gw_node; 104 } 105 106 /** 107 * batadv_gw_get_selected_orig() - Get originator of currently selected gateway 108 * @bat_priv: the bat priv with all the soft interface information 109 * 110 * Return: orig_node of selected gateway (with increased refcnt), NULL on errors 111 */ 112 struct batadv_orig_node * 113 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv) 114 { 115 struct batadv_gw_node *gw_node; 116 struct batadv_orig_node *orig_node = NULL; 117 118 gw_node = batadv_gw_get_selected_gw_node(bat_priv); 119 if (!gw_node) 120 goto out; 121 122 rcu_read_lock(); 123 orig_node = gw_node->orig_node; 124 if (!orig_node) 125 goto unlock; 126 127 if (!kref_get_unless_zero(&orig_node->refcount)) 128 orig_node = NULL; 129 130 unlock: 131 rcu_read_unlock(); 132 out: 133 if (gw_node) 134 batadv_gw_node_put(gw_node); 135 return orig_node; 136 } 137 138 static void batadv_gw_select(struct batadv_priv *bat_priv, 139 struct batadv_gw_node *new_gw_node) 140 { 141 struct batadv_gw_node *curr_gw_node; 142 143 spin_lock_bh(&bat_priv->gw.list_lock); 144 145 if (new_gw_node) 146 kref_get(&new_gw_node->refcount); 147 148 curr_gw_node = rcu_replace_pointer(bat_priv->gw.curr_gw, new_gw_node, 149 true); 150 151 if (curr_gw_node) 152 batadv_gw_node_put(curr_gw_node); 153 154 spin_unlock_bh(&bat_priv->gw.list_lock); 155 } 156 157 /** 158 * batadv_gw_reselect() - force a gateway reselection 159 * @bat_priv: the bat priv with all the soft interface information 160 * 161 * Set a flag to remind the GW component to perform a new gateway reselection. 162 * However this function does not ensure that the current gateway is going to be 163 * deselected. The reselection mechanism may elect the same gateway once again. 164 * 165 * This means that invoking batadv_gw_reselect() does not guarantee a gateway 166 * change and therefore a uevent is not necessarily expected. 167 */ 168 void batadv_gw_reselect(struct batadv_priv *bat_priv) 169 { 170 atomic_set(&bat_priv->gw.reselect, 1); 171 } 172 173 /** 174 * batadv_gw_check_client_stop() - check if client mode has been switched off 175 * @bat_priv: the bat priv with all the soft interface information 176 * 177 * This function assumes the caller has checked that the gw state *is actually 178 * changing*. This function is not supposed to be called when there is no state 179 * change. 180 */ 181 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv) 182 { 183 struct batadv_gw_node *curr_gw; 184 185 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) 186 return; 187 188 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 189 if (!curr_gw) 190 return; 191 192 /* deselect the current gateway so that next time that client mode is 193 * enabled a proper GW_ADD event can be sent 194 */ 195 batadv_gw_select(bat_priv, NULL); 196 197 /* if batman-adv is switching the gw client mode off and a gateway was 198 * already selected, send a DEL uevent 199 */ 200 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL); 201 202 batadv_gw_node_put(curr_gw); 203 } 204 205 /** 206 * batadv_gw_election() - Elect the best gateway 207 * @bat_priv: the bat priv with all the soft interface information 208 */ 209 void batadv_gw_election(struct batadv_priv *bat_priv) 210 { 211 struct batadv_gw_node *curr_gw = NULL; 212 struct batadv_gw_node *next_gw = NULL; 213 struct batadv_neigh_node *router = NULL; 214 struct batadv_neigh_ifinfo *router_ifinfo = NULL; 215 char gw_addr[18] = { '\0' }; 216 217 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) 218 goto out; 219 220 if (!bat_priv->algo_ops->gw.get_best_gw_node) 221 goto out; 222 223 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 224 225 if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw) 226 goto out; 227 228 /* if gw.reselect is set to 1 it means that a previous call to 229 * gw.is_eligible() said that we have a new best GW, therefore it can 230 * now be picked from the list and selected 231 */ 232 next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv); 233 234 if (curr_gw == next_gw) 235 goto out; 236 237 if (next_gw) { 238 sprintf(gw_addr, "%pM", next_gw->orig_node->orig); 239 240 router = batadv_orig_router_get(next_gw->orig_node, 241 BATADV_IF_DEFAULT); 242 if (!router) { 243 batadv_gw_reselect(bat_priv); 244 goto out; 245 } 246 247 router_ifinfo = batadv_neigh_ifinfo_get(router, 248 BATADV_IF_DEFAULT); 249 if (!router_ifinfo) { 250 batadv_gw_reselect(bat_priv); 251 goto out; 252 } 253 } 254 255 if (curr_gw && !next_gw) { 256 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 257 "Removing selected gateway - no gateway in range\n"); 258 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, 259 NULL); 260 } else if (!curr_gw && next_gw) { 261 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 262 "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 263 next_gw->orig_node->orig, 264 next_gw->bandwidth_down / 10, 265 next_gw->bandwidth_down % 10, 266 next_gw->bandwidth_up / 10, 267 next_gw->bandwidth_up % 10, 268 router_ifinfo->bat_iv.tq_avg); 269 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD, 270 gw_addr); 271 } else { 272 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 273 "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 274 next_gw->orig_node->orig, 275 next_gw->bandwidth_down / 10, 276 next_gw->bandwidth_down % 10, 277 next_gw->bandwidth_up / 10, 278 next_gw->bandwidth_up % 10, 279 router_ifinfo->bat_iv.tq_avg); 280 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE, 281 gw_addr); 282 } 283 284 batadv_gw_select(bat_priv, next_gw); 285 286 out: 287 if (curr_gw) 288 batadv_gw_node_put(curr_gw); 289 if (next_gw) 290 batadv_gw_node_put(next_gw); 291 if (router) 292 batadv_neigh_node_put(router); 293 if (router_ifinfo) 294 batadv_neigh_ifinfo_put(router_ifinfo); 295 } 296 297 /** 298 * batadv_gw_check_election() - Elect orig node as best gateway when eligible 299 * @bat_priv: the bat priv with all the soft interface information 300 * @orig_node: orig node which is to be checked 301 */ 302 void batadv_gw_check_election(struct batadv_priv *bat_priv, 303 struct batadv_orig_node *orig_node) 304 { 305 struct batadv_orig_node *curr_gw_orig; 306 307 /* abort immediately if the routing algorithm does not support gateway 308 * election 309 */ 310 if (!bat_priv->algo_ops->gw.is_eligible) 311 return; 312 313 curr_gw_orig = batadv_gw_get_selected_orig(bat_priv); 314 if (!curr_gw_orig) 315 goto reselect; 316 317 /* this node already is the gateway */ 318 if (curr_gw_orig == orig_node) 319 goto out; 320 321 if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig, 322 orig_node)) 323 goto out; 324 325 reselect: 326 batadv_gw_reselect(bat_priv); 327 out: 328 if (curr_gw_orig) 329 batadv_orig_node_put(curr_gw_orig); 330 } 331 332 /** 333 * batadv_gw_node_add() - add gateway node to list of available gateways 334 * @bat_priv: the bat priv with all the soft interface information 335 * @orig_node: originator announcing gateway capabilities 336 * @gateway: announced bandwidth information 337 * 338 * Has to be called with the appropriate locks being acquired 339 * (gw.list_lock). 340 */ 341 static void batadv_gw_node_add(struct batadv_priv *bat_priv, 342 struct batadv_orig_node *orig_node, 343 struct batadv_tvlv_gateway_data *gateway) 344 { 345 struct batadv_gw_node *gw_node; 346 347 lockdep_assert_held(&bat_priv->gw.list_lock); 348 349 if (gateway->bandwidth_down == 0) 350 return; 351 352 gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC); 353 if (!gw_node) 354 return; 355 356 kref_init(&gw_node->refcount); 357 INIT_HLIST_NODE(&gw_node->list); 358 kref_get(&orig_node->refcount); 359 gw_node->orig_node = orig_node; 360 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 361 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 362 363 kref_get(&gw_node->refcount); 364 hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list); 365 bat_priv->gw.generation++; 366 367 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 368 "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", 369 orig_node->orig, 370 ntohl(gateway->bandwidth_down) / 10, 371 ntohl(gateway->bandwidth_down) % 10, 372 ntohl(gateway->bandwidth_up) / 10, 373 ntohl(gateway->bandwidth_up) % 10); 374 375 /* don't return reference to new gw_node */ 376 batadv_gw_node_put(gw_node); 377 } 378 379 /** 380 * batadv_gw_node_get() - retrieve gateway node from list of available gateways 381 * @bat_priv: the bat priv with all the soft interface information 382 * @orig_node: originator announcing gateway capabilities 383 * 384 * Return: gateway node if found or NULL otherwise. 385 */ 386 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv, 387 struct batadv_orig_node *orig_node) 388 { 389 struct batadv_gw_node *gw_node_tmp, *gw_node = NULL; 390 391 rcu_read_lock(); 392 hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list, 393 list) { 394 if (gw_node_tmp->orig_node != orig_node) 395 continue; 396 397 if (!kref_get_unless_zero(&gw_node_tmp->refcount)) 398 continue; 399 400 gw_node = gw_node_tmp; 401 break; 402 } 403 rcu_read_unlock(); 404 405 return gw_node; 406 } 407 408 /** 409 * batadv_gw_node_update() - update list of available gateways with changed 410 * bandwidth information 411 * @bat_priv: the bat priv with all the soft interface information 412 * @orig_node: originator announcing gateway capabilities 413 * @gateway: announced bandwidth information 414 */ 415 void batadv_gw_node_update(struct batadv_priv *bat_priv, 416 struct batadv_orig_node *orig_node, 417 struct batadv_tvlv_gateway_data *gateway) 418 { 419 struct batadv_gw_node *gw_node, *curr_gw = NULL; 420 421 spin_lock_bh(&bat_priv->gw.list_lock); 422 gw_node = batadv_gw_node_get(bat_priv, orig_node); 423 if (!gw_node) { 424 batadv_gw_node_add(bat_priv, orig_node, gateway); 425 spin_unlock_bh(&bat_priv->gw.list_lock); 426 goto out; 427 } 428 spin_unlock_bh(&bat_priv->gw.list_lock); 429 430 if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) && 431 gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)) 432 goto out; 433 434 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 435 "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", 436 orig_node->orig, 437 gw_node->bandwidth_down / 10, 438 gw_node->bandwidth_down % 10, 439 gw_node->bandwidth_up / 10, 440 gw_node->bandwidth_up % 10, 441 ntohl(gateway->bandwidth_down) / 10, 442 ntohl(gateway->bandwidth_down) % 10, 443 ntohl(gateway->bandwidth_up) / 10, 444 ntohl(gateway->bandwidth_up) % 10); 445 446 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 447 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 448 449 if (ntohl(gateway->bandwidth_down) == 0) { 450 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 451 "Gateway %pM removed from gateway list\n", 452 orig_node->orig); 453 454 /* Note: We don't need a NULL check here, since curr_gw never 455 * gets dereferenced. 456 */ 457 spin_lock_bh(&bat_priv->gw.list_lock); 458 if (!hlist_unhashed(&gw_node->list)) { 459 hlist_del_init_rcu(&gw_node->list); 460 batadv_gw_node_put(gw_node); 461 bat_priv->gw.generation++; 462 } 463 spin_unlock_bh(&bat_priv->gw.list_lock); 464 465 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 466 if (gw_node == curr_gw) 467 batadv_gw_reselect(bat_priv); 468 469 if (curr_gw) 470 batadv_gw_node_put(curr_gw); 471 } 472 473 out: 474 if (gw_node) 475 batadv_gw_node_put(gw_node); 476 } 477 478 /** 479 * batadv_gw_node_delete() - Remove orig_node from gateway list 480 * @bat_priv: the bat priv with all the soft interface information 481 * @orig_node: orig node which is currently in process of being removed 482 */ 483 void batadv_gw_node_delete(struct batadv_priv *bat_priv, 484 struct batadv_orig_node *orig_node) 485 { 486 struct batadv_tvlv_gateway_data gateway; 487 488 gateway.bandwidth_down = 0; 489 gateway.bandwidth_up = 0; 490 491 batadv_gw_node_update(bat_priv, orig_node, &gateway); 492 } 493 494 /** 495 * batadv_gw_node_free() - Free gateway information from soft interface 496 * @bat_priv: the bat priv with all the soft interface information 497 */ 498 void batadv_gw_node_free(struct batadv_priv *bat_priv) 499 { 500 struct batadv_gw_node *gw_node; 501 struct hlist_node *node_tmp; 502 503 spin_lock_bh(&bat_priv->gw.list_lock); 504 hlist_for_each_entry_safe(gw_node, node_tmp, 505 &bat_priv->gw.gateway_list, list) { 506 hlist_del_init_rcu(&gw_node->list); 507 batadv_gw_node_put(gw_node); 508 bat_priv->gw.generation++; 509 } 510 spin_unlock_bh(&bat_priv->gw.list_lock); 511 } 512 513 /** 514 * batadv_gw_dump() - Dump gateways into a message 515 * @msg: Netlink message to dump into 516 * @cb: Control block containing additional options 517 * 518 * Return: Error code, or length of message 519 */ 520 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb) 521 { 522 struct batadv_hard_iface *primary_if = NULL; 523 struct net *net = sock_net(cb->skb->sk); 524 struct net_device *soft_iface; 525 struct batadv_priv *bat_priv; 526 int ifindex; 527 int ret; 528 529 ifindex = batadv_netlink_get_ifindex(cb->nlh, 530 BATADV_ATTR_MESH_IFINDEX); 531 if (!ifindex) 532 return -EINVAL; 533 534 soft_iface = dev_get_by_index(net, ifindex); 535 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) { 536 ret = -ENODEV; 537 goto out; 538 } 539 540 bat_priv = netdev_priv(soft_iface); 541 542 primary_if = batadv_primary_if_get_selected(bat_priv); 543 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) { 544 ret = -ENOENT; 545 goto out; 546 } 547 548 if (!bat_priv->algo_ops->gw.dump) { 549 ret = -EOPNOTSUPP; 550 goto out; 551 } 552 553 bat_priv->algo_ops->gw.dump(msg, cb, bat_priv); 554 555 ret = msg->len; 556 557 out: 558 if (primary_if) 559 batadv_hardif_put(primary_if); 560 if (soft_iface) 561 dev_put(soft_iface); 562 563 return ret; 564 } 565 566 /** 567 * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message 568 * @skb: the packet to check 569 * @header_len: a pointer to the batman-adv header size 570 * @chaddr: buffer where the client address will be stored. Valid 571 * only if the function returns BATADV_DHCP_TO_CLIENT 572 * 573 * This function may re-allocate the data buffer of the skb passed as argument. 574 * 575 * Return: 576 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error 577 * while parsing it 578 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server 579 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client 580 */ 581 enum batadv_dhcp_recipient 582 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, 583 u8 *chaddr) 584 { 585 enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; 586 struct ethhdr *ethhdr; 587 struct iphdr *iphdr; 588 struct ipv6hdr *ipv6hdr; 589 struct udphdr *udphdr; 590 struct vlan_ethhdr *vhdr; 591 int chaddr_offset; 592 __be16 proto; 593 u8 *p; 594 595 /* check for ethernet header */ 596 if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) 597 return BATADV_DHCP_NO; 598 599 ethhdr = eth_hdr(skb); 600 proto = ethhdr->h_proto; 601 *header_len += ETH_HLEN; 602 603 /* check for initial vlan header */ 604 if (proto == htons(ETH_P_8021Q)) { 605 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) 606 return BATADV_DHCP_NO; 607 608 vhdr = vlan_eth_hdr(skb); 609 proto = vhdr->h_vlan_encapsulated_proto; 610 *header_len += VLAN_HLEN; 611 } 612 613 /* check for ip header */ 614 switch (proto) { 615 case htons(ETH_P_IP): 616 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) 617 return BATADV_DHCP_NO; 618 619 iphdr = (struct iphdr *)(skb->data + *header_len); 620 *header_len += iphdr->ihl * 4; 621 622 /* check for udp header */ 623 if (iphdr->protocol != IPPROTO_UDP) 624 return BATADV_DHCP_NO; 625 626 break; 627 case htons(ETH_P_IPV6): 628 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) 629 return BATADV_DHCP_NO; 630 631 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); 632 *header_len += sizeof(*ipv6hdr); 633 634 /* check for udp header */ 635 if (ipv6hdr->nexthdr != IPPROTO_UDP) 636 return BATADV_DHCP_NO; 637 638 break; 639 default: 640 return BATADV_DHCP_NO; 641 } 642 643 if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) 644 return BATADV_DHCP_NO; 645 646 udphdr = (struct udphdr *)(skb->data + *header_len); 647 *header_len += sizeof(*udphdr); 648 649 /* check for bootp port */ 650 switch (proto) { 651 case htons(ETH_P_IP): 652 if (udphdr->dest == htons(67)) 653 ret = BATADV_DHCP_TO_SERVER; 654 else if (udphdr->source == htons(67)) 655 ret = BATADV_DHCP_TO_CLIENT; 656 break; 657 case htons(ETH_P_IPV6): 658 if (udphdr->dest == htons(547)) 659 ret = BATADV_DHCP_TO_SERVER; 660 else if (udphdr->source == htons(547)) 661 ret = BATADV_DHCP_TO_CLIENT; 662 break; 663 } 664 665 chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; 666 /* store the client address if the message is going to a client */ 667 if (ret == BATADV_DHCP_TO_CLIENT) { 668 if (!pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) 669 return BATADV_DHCP_NO; 670 671 /* check if the DHCP packet carries an Ethernet DHCP */ 672 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET; 673 if (*p != BATADV_DHCP_HTYPE_ETHERNET) 674 return BATADV_DHCP_NO; 675 676 /* check if the DHCP packet carries a valid Ethernet address */ 677 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET; 678 if (*p != ETH_ALEN) 679 return BATADV_DHCP_NO; 680 681 ether_addr_copy(chaddr, skb->data + chaddr_offset); 682 } 683 684 return ret; 685 } 686 687 /** 688 * batadv_gw_out_of_range() - check if the dhcp request destination is the best 689 * gateway 690 * @bat_priv: the bat priv with all the soft interface information 691 * @skb: the outgoing packet 692 * 693 * Check if the skb is a DHCP request and if it is sent to the current best GW 694 * server. Due to topology changes it may be the case that the GW server 695 * previously selected is not the best one anymore. 696 * 697 * This call might reallocate skb data. 698 * Must be invoked only when the DHCP packet is going TO a DHCP SERVER. 699 * 700 * Return: true if the packet destination is unicast and it is not the best gw, 701 * false otherwise. 702 */ 703 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, 704 struct sk_buff *skb) 705 { 706 struct batadv_neigh_node *neigh_curr = NULL; 707 struct batadv_neigh_node *neigh_old = NULL; 708 struct batadv_orig_node *orig_dst_node = NULL; 709 struct batadv_gw_node *gw_node = NULL; 710 struct batadv_gw_node *curr_gw = NULL; 711 struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo; 712 struct ethhdr *ethhdr = (struct ethhdr *)skb->data; 713 bool out_of_range = false; 714 u8 curr_tq_avg; 715 unsigned short vid; 716 717 vid = batadv_get_vid(skb, 0); 718 719 if (is_multicast_ether_addr(ethhdr->h_dest)) 720 goto out; 721 722 orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, 723 ethhdr->h_dest, vid); 724 if (!orig_dst_node) 725 goto out; 726 727 gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); 728 if (!gw_node) 729 goto out; 730 731 switch (atomic_read(&bat_priv->gw.mode)) { 732 case BATADV_GW_MODE_SERVER: 733 /* If we are a GW then we are our best GW. We can artificially 734 * set the tq towards ourself as the maximum value 735 */ 736 curr_tq_avg = BATADV_TQ_MAX_VALUE; 737 break; 738 case BATADV_GW_MODE_CLIENT: 739 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 740 if (!curr_gw) 741 goto out; 742 743 /* packet is going to our gateway */ 744 if (curr_gw->orig_node == orig_dst_node) 745 goto out; 746 747 /* If the dhcp packet has been sent to a different gw, 748 * we have to evaluate whether the old gw is still 749 * reliable enough 750 */ 751 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node, 752 NULL); 753 if (!neigh_curr) 754 goto out; 755 756 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, 757 BATADV_IF_DEFAULT); 758 if (!curr_ifinfo) 759 goto out; 760 761 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; 762 batadv_neigh_ifinfo_put(curr_ifinfo); 763 764 break; 765 case BATADV_GW_MODE_OFF: 766 default: 767 goto out; 768 } 769 770 neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); 771 if (!neigh_old) 772 goto out; 773 774 old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); 775 if (!old_ifinfo) 776 goto out; 777 778 if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) 779 out_of_range = true; 780 batadv_neigh_ifinfo_put(old_ifinfo); 781 782 out: 783 if (orig_dst_node) 784 batadv_orig_node_put(orig_dst_node); 785 if (curr_gw) 786 batadv_gw_node_put(curr_gw); 787 if (gw_node) 788 batadv_gw_node_put(gw_node); 789 if (neigh_old) 790 batadv_neigh_node_put(neigh_old); 791 if (neigh_curr) 792 batadv_neigh_node_put(neigh_curr); 793 return out_of_range; 794 } 795