1 /* Copyright (C) 2009-2016 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.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.list, list) { 380 if (gw_node_tmp->orig_node != orig_node) 381 continue; 382 383 if (!kref_get_unless_zero(&gw_node_tmp->refcount)) 384 continue; 385 386 gw_node = gw_node_tmp; 387 break; 388 } 389 rcu_read_unlock(); 390 391 return gw_node; 392 } 393 394 /** 395 * batadv_gw_node_update - update list of available gateways with changed 396 * bandwidth information 397 * @bat_priv: the bat priv with all the soft interface information 398 * @orig_node: originator announcing gateway capabilities 399 * @gateway: announced bandwidth information 400 */ 401 void batadv_gw_node_update(struct batadv_priv *bat_priv, 402 struct batadv_orig_node *orig_node, 403 struct batadv_tvlv_gateway_data *gateway) 404 { 405 struct batadv_gw_node *gw_node, *curr_gw = NULL; 406 407 gw_node = batadv_gw_node_get(bat_priv, orig_node); 408 if (!gw_node) { 409 batadv_gw_node_add(bat_priv, orig_node, gateway); 410 goto out; 411 } 412 413 if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) && 414 (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))) 415 goto out; 416 417 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 418 "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", 419 orig_node->orig, 420 gw_node->bandwidth_down / 10, 421 gw_node->bandwidth_down % 10, 422 gw_node->bandwidth_up / 10, 423 gw_node->bandwidth_up % 10, 424 ntohl(gateway->bandwidth_down) / 10, 425 ntohl(gateway->bandwidth_down) % 10, 426 ntohl(gateway->bandwidth_up) / 10, 427 ntohl(gateway->bandwidth_up) % 10); 428 429 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 430 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 431 432 if (ntohl(gateway->bandwidth_down) == 0) { 433 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 434 "Gateway %pM removed from gateway list\n", 435 orig_node->orig); 436 437 /* Note: We don't need a NULL check here, since curr_gw never 438 * gets dereferenced. 439 */ 440 spin_lock_bh(&bat_priv->gw.list_lock); 441 if (!hlist_unhashed(&gw_node->list)) { 442 hlist_del_init_rcu(&gw_node->list); 443 batadv_gw_node_put(gw_node); 444 } 445 spin_unlock_bh(&bat_priv->gw.list_lock); 446 447 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 448 if (gw_node == curr_gw) 449 batadv_gw_reselect(bat_priv); 450 451 if (curr_gw) 452 batadv_gw_node_put(curr_gw); 453 } 454 455 out: 456 if (gw_node) 457 batadv_gw_node_put(gw_node); 458 } 459 460 void batadv_gw_node_delete(struct batadv_priv *bat_priv, 461 struct batadv_orig_node *orig_node) 462 { 463 struct batadv_tvlv_gateway_data gateway; 464 465 gateway.bandwidth_down = 0; 466 gateway.bandwidth_up = 0; 467 468 batadv_gw_node_update(bat_priv, orig_node, &gateway); 469 } 470 471 void batadv_gw_node_free(struct batadv_priv *bat_priv) 472 { 473 struct batadv_gw_node *gw_node; 474 struct hlist_node *node_tmp; 475 476 spin_lock_bh(&bat_priv->gw.list_lock); 477 hlist_for_each_entry_safe(gw_node, node_tmp, 478 &bat_priv->gw.list, list) { 479 hlist_del_init_rcu(&gw_node->list); 480 batadv_gw_node_put(gw_node); 481 } 482 spin_unlock_bh(&bat_priv->gw.list_lock); 483 } 484 485 #ifdef CONFIG_BATMAN_ADV_DEBUGFS 486 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset) 487 { 488 struct net_device *net_dev = (struct net_device *)seq->private; 489 struct batadv_priv *bat_priv = netdev_priv(net_dev); 490 struct batadv_hard_iface *primary_if; 491 492 primary_if = batadv_seq_print_text_primary_if_get(seq); 493 if (!primary_if) 494 return 0; 495 496 seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n", 497 BATADV_SOURCE_VERSION, primary_if->net_dev->name, 498 primary_if->net_dev->dev_addr, net_dev->name, 499 bat_priv->algo_ops->name); 500 501 batadv_hardif_put(primary_if); 502 503 if (!bat_priv->algo_ops->gw.print) { 504 seq_puts(seq, 505 "No printing function for this routing protocol\n"); 506 return 0; 507 } 508 509 bat_priv->algo_ops->gw.print(bat_priv, seq); 510 511 return 0; 512 } 513 #endif 514 515 /** 516 * batadv_gw_dump - Dump gateways into a message 517 * @msg: Netlink message to dump into 518 * @cb: Control block containing additional options 519 * 520 * Return: Error code, or length of message 521 */ 522 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb) 523 { 524 struct batadv_hard_iface *primary_if = NULL; 525 struct net *net = sock_net(cb->skb->sk); 526 struct net_device *soft_iface; 527 struct batadv_priv *bat_priv; 528 int ifindex; 529 int ret; 530 531 ifindex = batadv_netlink_get_ifindex(cb->nlh, 532 BATADV_ATTR_MESH_IFINDEX); 533 if (!ifindex) 534 return -EINVAL; 535 536 soft_iface = dev_get_by_index(net, ifindex); 537 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) { 538 ret = -ENODEV; 539 goto out; 540 } 541 542 bat_priv = netdev_priv(soft_iface); 543 544 primary_if = batadv_primary_if_get_selected(bat_priv); 545 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) { 546 ret = -ENOENT; 547 goto out; 548 } 549 550 if (!bat_priv->algo_ops->gw.dump) { 551 ret = -EOPNOTSUPP; 552 goto out; 553 } 554 555 bat_priv->algo_ops->gw.dump(msg, cb, bat_priv); 556 557 ret = msg->len; 558 559 out: 560 if (primary_if) 561 batadv_hardif_put(primary_if); 562 if (soft_iface) 563 dev_put(soft_iface); 564 565 return ret; 566 } 567 568 /** 569 * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message 570 * @skb: the packet to check 571 * @header_len: a pointer to the batman-adv header size 572 * @chaddr: buffer where the client address will be stored. Valid 573 * only if the function returns BATADV_DHCP_TO_CLIENT 574 * 575 * This function may re-allocate the data buffer of the skb passed as argument. 576 * 577 * Return: 578 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error 579 * while parsing it 580 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server 581 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client 582 */ 583 enum batadv_dhcp_recipient 584 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, 585 u8 *chaddr) 586 { 587 enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; 588 struct ethhdr *ethhdr; 589 struct iphdr *iphdr; 590 struct ipv6hdr *ipv6hdr; 591 struct udphdr *udphdr; 592 struct vlan_ethhdr *vhdr; 593 int chaddr_offset; 594 __be16 proto; 595 u8 *p; 596 597 /* check for ethernet header */ 598 if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) 599 return BATADV_DHCP_NO; 600 601 ethhdr = eth_hdr(skb); 602 proto = ethhdr->h_proto; 603 *header_len += ETH_HLEN; 604 605 /* check for initial vlan header */ 606 if (proto == htons(ETH_P_8021Q)) { 607 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) 608 return BATADV_DHCP_NO; 609 610 vhdr = vlan_eth_hdr(skb); 611 proto = vhdr->h_vlan_encapsulated_proto; 612 *header_len += VLAN_HLEN; 613 } 614 615 /* check for ip header */ 616 switch (proto) { 617 case htons(ETH_P_IP): 618 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) 619 return BATADV_DHCP_NO; 620 621 iphdr = (struct iphdr *)(skb->data + *header_len); 622 *header_len += iphdr->ihl * 4; 623 624 /* check for udp header */ 625 if (iphdr->protocol != IPPROTO_UDP) 626 return BATADV_DHCP_NO; 627 628 break; 629 case htons(ETH_P_IPV6): 630 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) 631 return BATADV_DHCP_NO; 632 633 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); 634 *header_len += sizeof(*ipv6hdr); 635 636 /* check for udp header */ 637 if (ipv6hdr->nexthdr != IPPROTO_UDP) 638 return BATADV_DHCP_NO; 639 640 break; 641 default: 642 return BATADV_DHCP_NO; 643 } 644 645 if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) 646 return BATADV_DHCP_NO; 647 648 udphdr = (struct udphdr *)(skb->data + *header_len); 649 *header_len += sizeof(*udphdr); 650 651 /* check for bootp port */ 652 switch (proto) { 653 case htons(ETH_P_IP): 654 if (udphdr->dest == htons(67)) 655 ret = BATADV_DHCP_TO_SERVER; 656 else if (udphdr->source == htons(67)) 657 ret = BATADV_DHCP_TO_CLIENT; 658 break; 659 case htons(ETH_P_IPV6): 660 if (udphdr->dest == htons(547)) 661 ret = BATADV_DHCP_TO_SERVER; 662 else if (udphdr->source == htons(547)) 663 ret = BATADV_DHCP_TO_CLIENT; 664 break; 665 } 666 667 chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; 668 /* store the client address if the message is going to a client */ 669 if (ret == BATADV_DHCP_TO_CLIENT && 670 pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) { 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 gw 689 * @bat_priv: the bat priv with all the soft interface information 690 * @skb: the outgoing packet 691 * 692 * Check if the skb is a DHCP request and if it is sent to the current best GW 693 * server. Due to topology changes it may be the case that the GW server 694 * previously selected is not the best one anymore. 695 * 696 * This call might reallocate skb data. 697 * Must be invoked only when the DHCP packet is going TO a DHCP SERVER. 698 * 699 * Return: true if the packet destination is unicast and it is not the best gw, 700 * false otherwise. 701 */ 702 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, 703 struct sk_buff *skb) 704 { 705 struct batadv_neigh_node *neigh_curr = NULL; 706 struct batadv_neigh_node *neigh_old = NULL; 707 struct batadv_orig_node *orig_dst_node = NULL; 708 struct batadv_gw_node *gw_node = NULL; 709 struct batadv_gw_node *curr_gw = NULL; 710 struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo; 711 struct ethhdr *ethhdr = (struct ethhdr *)skb->data; 712 bool out_of_range = false; 713 u8 curr_tq_avg; 714 unsigned short vid; 715 716 vid = batadv_get_vid(skb, 0); 717 718 orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, 719 ethhdr->h_dest, vid); 720 if (!orig_dst_node) 721 goto out; 722 723 gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); 724 if (!gw_node) 725 goto out; 726 727 switch (atomic_read(&bat_priv->gw.mode)) { 728 case BATADV_GW_MODE_SERVER: 729 /* If we are a GW then we are our best GW. We can artificially 730 * set the tq towards ourself as the maximum value 731 */ 732 curr_tq_avg = BATADV_TQ_MAX_VALUE; 733 break; 734 case BATADV_GW_MODE_CLIENT: 735 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 736 if (!curr_gw) 737 goto out; 738 739 /* packet is going to our gateway */ 740 if (curr_gw->orig_node == orig_dst_node) 741 goto out; 742 743 /* If the dhcp packet has been sent to a different gw, 744 * we have to evaluate whether the old gw is still 745 * reliable enough 746 */ 747 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node, 748 NULL); 749 if (!neigh_curr) 750 goto out; 751 752 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, 753 BATADV_IF_DEFAULT); 754 if (!curr_ifinfo) 755 goto out; 756 757 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; 758 batadv_neigh_ifinfo_put(curr_ifinfo); 759 760 break; 761 case BATADV_GW_MODE_OFF: 762 default: 763 goto out; 764 } 765 766 neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); 767 if (!neigh_old) 768 goto out; 769 770 old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); 771 if (!old_ifinfo) 772 goto out; 773 774 if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) 775 out_of_range = true; 776 batadv_neigh_ifinfo_put(old_ifinfo); 777 778 out: 779 if (orig_dst_node) 780 batadv_orig_node_put(orig_dst_node); 781 if (curr_gw) 782 batadv_gw_node_put(curr_gw); 783 if (gw_node) 784 batadv_gw_node_put(gw_node); 785 if (neigh_old) 786 batadv_neigh_node_put(neigh_old); 787 if (neigh_curr) 788 batadv_neigh_node_put(neigh_curr); 789 return out_of_range; 790 } 791