1 /* Copyright (C) 2009-2017 B.A.T.M.A.N. contributors: 2 * 3 * Marek Lindner 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of version 2 of the GNU General Public 7 * License as published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, see <http://www.gnu.org/licenses/>. 16 */ 17 18 #include "gateway_client.h" 19 #include "main.h" 20 21 #include <linux/atomic.h> 22 #include <linux/byteorder/generic.h> 23 #include <linux/errno.h> 24 #include <linux/etherdevice.h> 25 #include <linux/fs.h> 26 #include <linux/if_ether.h> 27 #include <linux/if_vlan.h> 28 #include <linux/in.h> 29 #include <linux/ip.h> 30 #include <linux/ipv6.h> 31 #include <linux/kernel.h> 32 #include <linux/kref.h> 33 #include <linux/list.h> 34 #include <linux/netdevice.h> 35 #include <linux/netlink.h> 36 #include <linux/rculist.h> 37 #include <linux/rcupdate.h> 38 #include <linux/seq_file.h> 39 #include <linux/skbuff.h> 40 #include <linux/slab.h> 41 #include <linux/spinlock.h> 42 #include <linux/stddef.h> 43 #include <linux/udp.h> 44 #include <net/sock.h> 45 #include <uapi/linux/batman_adv.h> 46 47 #include "gateway_common.h" 48 #include "hard-interface.h" 49 #include "log.h" 50 #include "netlink.h" 51 #include "originator.h" 52 #include "packet.h" 53 #include "routing.h" 54 #include "soft-interface.h" 55 #include "sysfs.h" 56 #include "translation-table.h" 57 58 /* These are the offsets of the "hw type" and "hw address length" in the dhcp 59 * packet starting at the beginning of the dhcp header 60 */ 61 #define BATADV_DHCP_HTYPE_OFFSET 1 62 #define BATADV_DHCP_HLEN_OFFSET 2 63 /* Value of htype representing Ethernet */ 64 #define BATADV_DHCP_HTYPE_ETHERNET 0x01 65 /* This is the offset of the "chaddr" field in the dhcp packet starting at the 66 * beginning of the dhcp header 67 */ 68 #define BATADV_DHCP_CHADDR_OFFSET 28 69 70 /** 71 * batadv_gw_node_release - release gw_node from lists and queue for free after 72 * rcu grace period 73 * @ref: kref pointer of the gw_node 74 */ 75 static void batadv_gw_node_release(struct kref *ref) 76 { 77 struct batadv_gw_node *gw_node; 78 79 gw_node = container_of(ref, struct batadv_gw_node, refcount); 80 81 batadv_orig_node_put(gw_node->orig_node); 82 kfree_rcu(gw_node, rcu); 83 } 84 85 /** 86 * batadv_gw_node_put - decrement the gw_node refcounter and possibly release it 87 * @gw_node: gateway node to free 88 */ 89 void batadv_gw_node_put(struct batadv_gw_node *gw_node) 90 { 91 kref_put(&gw_node->refcount, batadv_gw_node_release); 92 } 93 94 struct batadv_gw_node * 95 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) 96 { 97 struct batadv_gw_node *gw_node; 98 99 rcu_read_lock(); 100 gw_node = rcu_dereference(bat_priv->gw.curr_gw); 101 if (!gw_node) 102 goto out; 103 104 if (!kref_get_unless_zero(&gw_node->refcount)) 105 gw_node = NULL; 106 107 out: 108 rcu_read_unlock(); 109 return gw_node; 110 } 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_dereference_protected(bat_priv->gw.curr_gw, 1); 149 rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node); 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 void batadv_gw_election(struct batadv_priv *bat_priv) 206 { 207 struct batadv_gw_node *curr_gw = NULL; 208 struct batadv_gw_node *next_gw = NULL; 209 struct batadv_neigh_node *router = NULL; 210 struct batadv_neigh_ifinfo *router_ifinfo = NULL; 211 char gw_addr[18] = { '\0' }; 212 213 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) 214 goto out; 215 216 if (!bat_priv->algo_ops->gw.get_best_gw_node) 217 goto out; 218 219 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 220 221 if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw) 222 goto out; 223 224 /* if gw.reselect is set to 1 it means that a previous call to 225 * gw.is_eligible() said that we have a new best GW, therefore it can 226 * now be picked from the list and selected 227 */ 228 next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv); 229 230 if (curr_gw == next_gw) 231 goto out; 232 233 if (next_gw) { 234 sprintf(gw_addr, "%pM", next_gw->orig_node->orig); 235 236 router = batadv_orig_router_get(next_gw->orig_node, 237 BATADV_IF_DEFAULT); 238 if (!router) { 239 batadv_gw_reselect(bat_priv); 240 goto out; 241 } 242 243 router_ifinfo = batadv_neigh_ifinfo_get(router, 244 BATADV_IF_DEFAULT); 245 if (!router_ifinfo) { 246 batadv_gw_reselect(bat_priv); 247 goto out; 248 } 249 } 250 251 if ((curr_gw) && (!next_gw)) { 252 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 253 "Removing selected gateway - no gateway in range\n"); 254 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, 255 NULL); 256 } else if ((!curr_gw) && (next_gw)) { 257 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 258 "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 259 next_gw->orig_node->orig, 260 next_gw->bandwidth_down / 10, 261 next_gw->bandwidth_down % 10, 262 next_gw->bandwidth_up / 10, 263 next_gw->bandwidth_up % 10, 264 router_ifinfo->bat_iv.tq_avg); 265 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD, 266 gw_addr); 267 } else { 268 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 269 "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 270 next_gw->orig_node->orig, 271 next_gw->bandwidth_down / 10, 272 next_gw->bandwidth_down % 10, 273 next_gw->bandwidth_up / 10, 274 next_gw->bandwidth_up % 10, 275 router_ifinfo->bat_iv.tq_avg); 276 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE, 277 gw_addr); 278 } 279 280 batadv_gw_select(bat_priv, next_gw); 281 282 out: 283 if (curr_gw) 284 batadv_gw_node_put(curr_gw); 285 if (next_gw) 286 batadv_gw_node_put(next_gw); 287 if (router) 288 batadv_neigh_node_put(router); 289 if (router_ifinfo) 290 batadv_neigh_ifinfo_put(router_ifinfo); 291 } 292 293 void batadv_gw_check_election(struct batadv_priv *bat_priv, 294 struct batadv_orig_node *orig_node) 295 { 296 struct batadv_orig_node *curr_gw_orig; 297 298 /* abort immediately if the routing algorithm does not support gateway 299 * election 300 */ 301 if (!bat_priv->algo_ops->gw.is_eligible) 302 return; 303 304 curr_gw_orig = batadv_gw_get_selected_orig(bat_priv); 305 if (!curr_gw_orig) 306 goto reselect; 307 308 /* this node already is the gateway */ 309 if (curr_gw_orig == orig_node) 310 goto out; 311 312 if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig, 313 orig_node)) 314 goto out; 315 316 reselect: 317 batadv_gw_reselect(bat_priv); 318 out: 319 if (curr_gw_orig) 320 batadv_orig_node_put(curr_gw_orig); 321 } 322 323 /** 324 * batadv_gw_node_add - add gateway node to list of available gateways 325 * @bat_priv: the bat priv with all the soft interface information 326 * @orig_node: originator announcing gateway capabilities 327 * @gateway: announced bandwidth information 328 */ 329 static void batadv_gw_node_add(struct batadv_priv *bat_priv, 330 struct batadv_orig_node *orig_node, 331 struct batadv_tvlv_gateway_data *gateway) 332 { 333 struct batadv_gw_node *gw_node; 334 335 if (gateway->bandwidth_down == 0) 336 return; 337 338 gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC); 339 if (!gw_node) 340 return; 341 342 kref_init(&gw_node->refcount); 343 INIT_HLIST_NODE(&gw_node->list); 344 kref_get(&orig_node->refcount); 345 gw_node->orig_node = orig_node; 346 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 347 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 348 349 spin_lock_bh(&bat_priv->gw.list_lock); 350 kref_get(&gw_node->refcount); 351 hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list); 352 spin_unlock_bh(&bat_priv->gw.list_lock); 353 354 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 355 "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", 356 orig_node->orig, 357 ntohl(gateway->bandwidth_down) / 10, 358 ntohl(gateway->bandwidth_down) % 10, 359 ntohl(gateway->bandwidth_up) / 10, 360 ntohl(gateway->bandwidth_up) % 10); 361 362 /* don't return reference to new gw_node */ 363 batadv_gw_node_put(gw_node); 364 } 365 366 /** 367 * batadv_gw_node_get - retrieve gateway node from list of available gateways 368 * @bat_priv: the bat priv with all the soft interface information 369 * @orig_node: originator announcing gateway capabilities 370 * 371 * Return: gateway node if found or NULL otherwise. 372 */ 373 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv, 374 struct batadv_orig_node *orig_node) 375 { 376 struct batadv_gw_node *gw_node_tmp, *gw_node = NULL; 377 378 rcu_read_lock(); 379 hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list, 380 list) { 381 if (gw_node_tmp->orig_node != orig_node) 382 continue; 383 384 if (!kref_get_unless_zero(&gw_node_tmp->refcount)) 385 continue; 386 387 gw_node = gw_node_tmp; 388 break; 389 } 390 rcu_read_unlock(); 391 392 return gw_node; 393 } 394 395 /** 396 * batadv_gw_node_update - update list of available gateways with changed 397 * bandwidth information 398 * @bat_priv: the bat priv with all the soft interface information 399 * @orig_node: originator announcing gateway capabilities 400 * @gateway: announced bandwidth information 401 */ 402 void batadv_gw_node_update(struct batadv_priv *bat_priv, 403 struct batadv_orig_node *orig_node, 404 struct batadv_tvlv_gateway_data *gateway) 405 { 406 struct batadv_gw_node *gw_node, *curr_gw = NULL; 407 408 gw_node = batadv_gw_node_get(bat_priv, orig_node); 409 if (!gw_node) { 410 batadv_gw_node_add(bat_priv, orig_node, gateway); 411 goto out; 412 } 413 414 if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) && 415 (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))) 416 goto out; 417 418 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 419 "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", 420 orig_node->orig, 421 gw_node->bandwidth_down / 10, 422 gw_node->bandwidth_down % 10, 423 gw_node->bandwidth_up / 10, 424 gw_node->bandwidth_up % 10, 425 ntohl(gateway->bandwidth_down) / 10, 426 ntohl(gateway->bandwidth_down) % 10, 427 ntohl(gateway->bandwidth_up) / 10, 428 ntohl(gateway->bandwidth_up) % 10); 429 430 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 431 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 432 433 if (ntohl(gateway->bandwidth_down) == 0) { 434 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 435 "Gateway %pM removed from gateway list\n", 436 orig_node->orig); 437 438 /* Note: We don't need a NULL check here, since curr_gw never 439 * gets dereferenced. 440 */ 441 spin_lock_bh(&bat_priv->gw.list_lock); 442 if (!hlist_unhashed(&gw_node->list)) { 443 hlist_del_init_rcu(&gw_node->list); 444 batadv_gw_node_put(gw_node); 445 } 446 spin_unlock_bh(&bat_priv->gw.list_lock); 447 448 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 449 if (gw_node == curr_gw) 450 batadv_gw_reselect(bat_priv); 451 452 if (curr_gw) 453 batadv_gw_node_put(curr_gw); 454 } 455 456 out: 457 if (gw_node) 458 batadv_gw_node_put(gw_node); 459 } 460 461 void batadv_gw_node_delete(struct batadv_priv *bat_priv, 462 struct batadv_orig_node *orig_node) 463 { 464 struct batadv_tvlv_gateway_data gateway; 465 466 gateway.bandwidth_down = 0; 467 gateway.bandwidth_up = 0; 468 469 batadv_gw_node_update(bat_priv, orig_node, &gateway); 470 } 471 472 void batadv_gw_node_free(struct batadv_priv *bat_priv) 473 { 474 struct batadv_gw_node *gw_node; 475 struct hlist_node *node_tmp; 476 477 spin_lock_bh(&bat_priv->gw.list_lock); 478 hlist_for_each_entry_safe(gw_node, node_tmp, 479 &bat_priv->gw.gateway_list, list) { 480 hlist_del_init_rcu(&gw_node->list); 481 batadv_gw_node_put(gw_node); 482 } 483 spin_unlock_bh(&bat_priv->gw.list_lock); 484 } 485 486 #ifdef CONFIG_BATMAN_ADV_DEBUGFS 487 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset) 488 { 489 struct net_device *net_dev = (struct net_device *)seq->private; 490 struct batadv_priv *bat_priv = netdev_priv(net_dev); 491 struct batadv_hard_iface *primary_if; 492 493 primary_if = batadv_seq_print_text_primary_if_get(seq); 494 if (!primary_if) 495 return 0; 496 497 seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n", 498 BATADV_SOURCE_VERSION, primary_if->net_dev->name, 499 primary_if->net_dev->dev_addr, net_dev->name, 500 bat_priv->algo_ops->name); 501 502 batadv_hardif_put(primary_if); 503 504 if (!bat_priv->algo_ops->gw.print) { 505 seq_puts(seq, 506 "No printing function for this routing protocol\n"); 507 return 0; 508 } 509 510 bat_priv->algo_ops->gw.print(bat_priv, seq); 511 512 return 0; 513 } 514 #endif 515 516 /** 517 * batadv_gw_dump - Dump gateways into a message 518 * @msg: Netlink message to dump into 519 * @cb: Control block containing additional options 520 * 521 * Return: Error code, or length of message 522 */ 523 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb) 524 { 525 struct batadv_hard_iface *primary_if = NULL; 526 struct net *net = sock_net(cb->skb->sk); 527 struct net_device *soft_iface; 528 struct batadv_priv *bat_priv; 529 int ifindex; 530 int ret; 531 532 ifindex = batadv_netlink_get_ifindex(cb->nlh, 533 BATADV_ATTR_MESH_IFINDEX); 534 if (!ifindex) 535 return -EINVAL; 536 537 soft_iface = dev_get_by_index(net, ifindex); 538 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) { 539 ret = -ENODEV; 540 goto out; 541 } 542 543 bat_priv = netdev_priv(soft_iface); 544 545 primary_if = batadv_primary_if_get_selected(bat_priv); 546 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) { 547 ret = -ENOENT; 548 goto out; 549 } 550 551 if (!bat_priv->algo_ops->gw.dump) { 552 ret = -EOPNOTSUPP; 553 goto out; 554 } 555 556 bat_priv->algo_ops->gw.dump(msg, cb, bat_priv); 557 558 ret = msg->len; 559 560 out: 561 if (primary_if) 562 batadv_hardif_put(primary_if); 563 if (soft_iface) 564 dev_put(soft_iface); 565 566 return ret; 567 } 568 569 /** 570 * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message 571 * @skb: the packet to check 572 * @header_len: a pointer to the batman-adv header size 573 * @chaddr: buffer where the client address will be stored. Valid 574 * only if the function returns BATADV_DHCP_TO_CLIENT 575 * 576 * This function may re-allocate the data buffer of the skb passed as argument. 577 * 578 * Return: 579 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error 580 * while parsing it 581 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server 582 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client 583 */ 584 enum batadv_dhcp_recipient 585 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, 586 u8 *chaddr) 587 { 588 enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; 589 struct ethhdr *ethhdr; 590 struct iphdr *iphdr; 591 struct ipv6hdr *ipv6hdr; 592 struct udphdr *udphdr; 593 struct vlan_ethhdr *vhdr; 594 int chaddr_offset; 595 __be16 proto; 596 u8 *p; 597 598 /* check for ethernet header */ 599 if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) 600 return BATADV_DHCP_NO; 601 602 ethhdr = eth_hdr(skb); 603 proto = ethhdr->h_proto; 604 *header_len += ETH_HLEN; 605 606 /* check for initial vlan header */ 607 if (proto == htons(ETH_P_8021Q)) { 608 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) 609 return BATADV_DHCP_NO; 610 611 vhdr = vlan_eth_hdr(skb); 612 proto = vhdr->h_vlan_encapsulated_proto; 613 *header_len += VLAN_HLEN; 614 } 615 616 /* check for ip header */ 617 switch (proto) { 618 case htons(ETH_P_IP): 619 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) 620 return BATADV_DHCP_NO; 621 622 iphdr = (struct iphdr *)(skb->data + *header_len); 623 *header_len += iphdr->ihl * 4; 624 625 /* check for udp header */ 626 if (iphdr->protocol != IPPROTO_UDP) 627 return BATADV_DHCP_NO; 628 629 break; 630 case htons(ETH_P_IPV6): 631 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) 632 return BATADV_DHCP_NO; 633 634 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); 635 *header_len += sizeof(*ipv6hdr); 636 637 /* check for udp header */ 638 if (ipv6hdr->nexthdr != IPPROTO_UDP) 639 return BATADV_DHCP_NO; 640 641 break; 642 default: 643 return BATADV_DHCP_NO; 644 } 645 646 if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) 647 return BATADV_DHCP_NO; 648 649 udphdr = (struct udphdr *)(skb->data + *header_len); 650 *header_len += sizeof(*udphdr); 651 652 /* check for bootp port */ 653 switch (proto) { 654 case htons(ETH_P_IP): 655 if (udphdr->dest == htons(67)) 656 ret = BATADV_DHCP_TO_SERVER; 657 else if (udphdr->source == htons(67)) 658 ret = BATADV_DHCP_TO_CLIENT; 659 break; 660 case htons(ETH_P_IPV6): 661 if (udphdr->dest == htons(547)) 662 ret = BATADV_DHCP_TO_SERVER; 663 else if (udphdr->source == htons(547)) 664 ret = BATADV_DHCP_TO_CLIENT; 665 break; 666 } 667 668 chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; 669 /* store the client address if the message is going to a client */ 670 if (ret == BATADV_DHCP_TO_CLIENT && 671 pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) { 672 /* check if the DHCP packet carries an Ethernet DHCP */ 673 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET; 674 if (*p != BATADV_DHCP_HTYPE_ETHERNET) 675 return BATADV_DHCP_NO; 676 677 /* check if the DHCP packet carries a valid Ethernet address */ 678 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET; 679 if (*p != ETH_ALEN) 680 return BATADV_DHCP_NO; 681 682 ether_addr_copy(chaddr, skb->data + chaddr_offset); 683 } 684 685 return ret; 686 } 687 688 /** 689 * batadv_gw_out_of_range - check if the dhcp request destination is the best gw 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; 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 orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, 720 ethhdr->h_dest, vid); 721 if (!orig_dst_node) 722 goto out; 723 724 gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); 725 if (!gw_node) 726 goto out; 727 728 switch (atomic_read(&bat_priv->gw.mode)) { 729 case BATADV_GW_MODE_SERVER: 730 /* If we are a GW then we are our best GW. We can artificially 731 * set the tq towards ourself as the maximum value 732 */ 733 curr_tq_avg = BATADV_TQ_MAX_VALUE; 734 break; 735 case BATADV_GW_MODE_CLIENT: 736 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 737 if (!curr_gw) 738 goto out; 739 740 /* packet is going to our gateway */ 741 if (curr_gw->orig_node == orig_dst_node) 742 goto out; 743 744 /* If the dhcp packet has been sent to a different gw, 745 * we have to evaluate whether the old gw is still 746 * reliable enough 747 */ 748 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node, 749 NULL); 750 if (!neigh_curr) 751 goto out; 752 753 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, 754 BATADV_IF_DEFAULT); 755 if (!curr_ifinfo) 756 goto out; 757 758 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; 759 batadv_neigh_ifinfo_put(curr_ifinfo); 760 761 break; 762 case BATADV_GW_MODE_OFF: 763 default: 764 goto out; 765 } 766 767 neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); 768 if (!neigh_old) 769 goto out; 770 771 old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); 772 if (!old_ifinfo) 773 goto out; 774 775 if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) 776 out_of_range = true; 777 batadv_neigh_ifinfo_put(old_ifinfo); 778 779 out: 780 if (orig_dst_node) 781 batadv_orig_node_put(orig_dst_node); 782 if (curr_gw) 783 batadv_gw_node_put(curr_gw); 784 if (gw_node) 785 batadv_gw_node_put(gw_node); 786 if (neigh_old) 787 batadv_neigh_node_put(neigh_old); 788 if (neigh_curr) 789 batadv_neigh_node_put(neigh_curr); 790 return out_of_range; 791 } 792