1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (C) 2009-2017 B.A.T.M.A.N. contributors: 3 * 4 * Marek Lindner 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of version 2 of the GNU General Public 8 * License as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, but 11 * WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 * General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #include "gateway_client.h" 20 #include "main.h" 21 22 #include <linux/atomic.h> 23 #include <linux/byteorder/generic.h> 24 #include <linux/errno.h> 25 #include <linux/etherdevice.h> 26 #include <linux/gfp.h> 27 #include <linux/if_ether.h> 28 #include <linux/if_vlan.h> 29 #include <linux/in.h> 30 #include <linux/ip.h> 31 #include <linux/ipv6.h> 32 #include <linux/kernel.h> 33 #include <linux/kref.h> 34 #include <linux/list.h> 35 #include <linux/netdevice.h> 36 #include <linux/netlink.h> 37 #include <linux/rculist.h> 38 #include <linux/rcupdate.h> 39 #include <linux/seq_file.h> 40 #include <linux/skbuff.h> 41 #include <linux/slab.h> 42 #include <linux/spinlock.h> 43 #include <linux/stddef.h> 44 #include <linux/udp.h> 45 #include <net/sock.h> 46 #include <uapi/linux/batadv_packet.h> 47 #include <uapi/linux/batman_adv.h> 48 49 #include "gateway_common.h" 50 #include "hard-interface.h" 51 #include "log.h" 52 #include "netlink.h" 53 #include "originator.h" 54 #include "routing.h" 55 #include "soft-interface.h" 56 #include "sysfs.h" 57 #include "translation-table.h" 58 59 /* These are the offsets of the "hw type" and "hw address length" in the dhcp 60 * packet starting at the beginning of the dhcp header 61 */ 62 #define BATADV_DHCP_HTYPE_OFFSET 1 63 #define BATADV_DHCP_HLEN_OFFSET 2 64 /* Value of htype representing Ethernet */ 65 #define BATADV_DHCP_HTYPE_ETHERNET 0x01 66 /* This is the offset of the "chaddr" field in the dhcp packet starting at the 67 * beginning of the dhcp header 68 */ 69 #define BATADV_DHCP_CHADDR_OFFSET 28 70 71 /** 72 * batadv_gw_node_release() - release gw_node from lists and queue for free 73 * after rcu grace period 74 * @ref: kref pointer of the gw_node 75 */ 76 static void batadv_gw_node_release(struct kref *ref) 77 { 78 struct batadv_gw_node *gw_node; 79 80 gw_node = container_of(ref, struct batadv_gw_node, refcount); 81 82 batadv_orig_node_put(gw_node->orig_node); 83 kfree_rcu(gw_node, rcu); 84 } 85 86 /** 87 * batadv_gw_node_put() - decrement the gw_node refcounter and possibly release 88 * it 89 * @gw_node: gateway node to free 90 */ 91 void batadv_gw_node_put(struct batadv_gw_node *gw_node) 92 { 93 kref_put(&gw_node->refcount, batadv_gw_node_release); 94 } 95 96 /** 97 * batadv_gw_get_selected_gw_node() - Get currently selected gateway 98 * @bat_priv: the bat priv with all the soft interface information 99 * 100 * Return: selected gateway (with increased refcnt), NULL on errors 101 */ 102 struct batadv_gw_node * 103 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv) 104 { 105 struct batadv_gw_node *gw_node; 106 107 rcu_read_lock(); 108 gw_node = rcu_dereference(bat_priv->gw.curr_gw); 109 if (!gw_node) 110 goto out; 111 112 if (!kref_get_unless_zero(&gw_node->refcount)) 113 gw_node = NULL; 114 115 out: 116 rcu_read_unlock(); 117 return gw_node; 118 } 119 120 /** 121 * batadv_gw_get_selected_orig() - Get originator of currently selected gateway 122 * @bat_priv: the bat priv with all the soft interface information 123 * 124 * Return: orig_node of selected gateway (with increased refcnt), NULL on errors 125 */ 126 struct batadv_orig_node * 127 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv) 128 { 129 struct batadv_gw_node *gw_node; 130 struct batadv_orig_node *orig_node = NULL; 131 132 gw_node = batadv_gw_get_selected_gw_node(bat_priv); 133 if (!gw_node) 134 goto out; 135 136 rcu_read_lock(); 137 orig_node = gw_node->orig_node; 138 if (!orig_node) 139 goto unlock; 140 141 if (!kref_get_unless_zero(&orig_node->refcount)) 142 orig_node = NULL; 143 144 unlock: 145 rcu_read_unlock(); 146 out: 147 if (gw_node) 148 batadv_gw_node_put(gw_node); 149 return orig_node; 150 } 151 152 static void batadv_gw_select(struct batadv_priv *bat_priv, 153 struct batadv_gw_node *new_gw_node) 154 { 155 struct batadv_gw_node *curr_gw_node; 156 157 spin_lock_bh(&bat_priv->gw.list_lock); 158 159 if (new_gw_node) 160 kref_get(&new_gw_node->refcount); 161 162 curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1); 163 rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node); 164 165 if (curr_gw_node) 166 batadv_gw_node_put(curr_gw_node); 167 168 spin_unlock_bh(&bat_priv->gw.list_lock); 169 } 170 171 /** 172 * batadv_gw_reselect() - force a gateway reselection 173 * @bat_priv: the bat priv with all the soft interface information 174 * 175 * Set a flag to remind the GW component to perform a new gateway reselection. 176 * However this function does not ensure that the current gateway is going to be 177 * deselected. The reselection mechanism may elect the same gateway once again. 178 * 179 * This means that invoking batadv_gw_reselect() does not guarantee a gateway 180 * change and therefore a uevent is not necessarily expected. 181 */ 182 void batadv_gw_reselect(struct batadv_priv *bat_priv) 183 { 184 atomic_set(&bat_priv->gw.reselect, 1); 185 } 186 187 /** 188 * batadv_gw_check_client_stop() - check if client mode has been switched off 189 * @bat_priv: the bat priv with all the soft interface information 190 * 191 * This function assumes the caller has checked that the gw state *is actually 192 * changing*. This function is not supposed to be called when there is no state 193 * change. 194 */ 195 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv) 196 { 197 struct batadv_gw_node *curr_gw; 198 199 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) 200 return; 201 202 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 203 if (!curr_gw) 204 return; 205 206 /* deselect the current gateway so that next time that client mode is 207 * enabled a proper GW_ADD event can be sent 208 */ 209 batadv_gw_select(bat_priv, NULL); 210 211 /* if batman-adv is switching the gw client mode off and a gateway was 212 * already selected, send a DEL uevent 213 */ 214 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL); 215 216 batadv_gw_node_put(curr_gw); 217 } 218 219 /** 220 * batadv_gw_election() - Elect the best gateway 221 * @bat_priv: the bat priv with all the soft interface information 222 */ 223 void batadv_gw_election(struct batadv_priv *bat_priv) 224 { 225 struct batadv_gw_node *curr_gw = NULL; 226 struct batadv_gw_node *next_gw = NULL; 227 struct batadv_neigh_node *router = NULL; 228 struct batadv_neigh_ifinfo *router_ifinfo = NULL; 229 char gw_addr[18] = { '\0' }; 230 231 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT) 232 goto out; 233 234 if (!bat_priv->algo_ops->gw.get_best_gw_node) 235 goto out; 236 237 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 238 239 if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw) 240 goto out; 241 242 /* if gw.reselect is set to 1 it means that a previous call to 243 * gw.is_eligible() said that we have a new best GW, therefore it can 244 * now be picked from the list and selected 245 */ 246 next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv); 247 248 if (curr_gw == next_gw) 249 goto out; 250 251 if (next_gw) { 252 sprintf(gw_addr, "%pM", next_gw->orig_node->orig); 253 254 router = batadv_orig_router_get(next_gw->orig_node, 255 BATADV_IF_DEFAULT); 256 if (!router) { 257 batadv_gw_reselect(bat_priv); 258 goto out; 259 } 260 261 router_ifinfo = batadv_neigh_ifinfo_get(router, 262 BATADV_IF_DEFAULT); 263 if (!router_ifinfo) { 264 batadv_gw_reselect(bat_priv); 265 goto out; 266 } 267 } 268 269 if (curr_gw && !next_gw) { 270 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 271 "Removing selected gateway - no gateway in range\n"); 272 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, 273 NULL); 274 } else if (!curr_gw && next_gw) { 275 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 276 "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 277 next_gw->orig_node->orig, 278 next_gw->bandwidth_down / 10, 279 next_gw->bandwidth_down % 10, 280 next_gw->bandwidth_up / 10, 281 next_gw->bandwidth_up % 10, 282 router_ifinfo->bat_iv.tq_avg); 283 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD, 284 gw_addr); 285 } else { 286 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 287 "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n", 288 next_gw->orig_node->orig, 289 next_gw->bandwidth_down / 10, 290 next_gw->bandwidth_down % 10, 291 next_gw->bandwidth_up / 10, 292 next_gw->bandwidth_up % 10, 293 router_ifinfo->bat_iv.tq_avg); 294 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE, 295 gw_addr); 296 } 297 298 batadv_gw_select(bat_priv, next_gw); 299 300 out: 301 if (curr_gw) 302 batadv_gw_node_put(curr_gw); 303 if (next_gw) 304 batadv_gw_node_put(next_gw); 305 if (router) 306 batadv_neigh_node_put(router); 307 if (router_ifinfo) 308 batadv_neigh_ifinfo_put(router_ifinfo); 309 } 310 311 /** 312 * batadv_gw_check_election() - Elect orig node as best gateway when eligible 313 * @bat_priv: the bat priv with all the soft interface information 314 * @orig_node: orig node which is to be checked 315 */ 316 void batadv_gw_check_election(struct batadv_priv *bat_priv, 317 struct batadv_orig_node *orig_node) 318 { 319 struct batadv_orig_node *curr_gw_orig; 320 321 /* abort immediately if the routing algorithm does not support gateway 322 * election 323 */ 324 if (!bat_priv->algo_ops->gw.is_eligible) 325 return; 326 327 curr_gw_orig = batadv_gw_get_selected_orig(bat_priv); 328 if (!curr_gw_orig) 329 goto reselect; 330 331 /* this node already is the gateway */ 332 if (curr_gw_orig == orig_node) 333 goto out; 334 335 if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig, 336 orig_node)) 337 goto out; 338 339 reselect: 340 batadv_gw_reselect(bat_priv); 341 out: 342 if (curr_gw_orig) 343 batadv_orig_node_put(curr_gw_orig); 344 } 345 346 /** 347 * batadv_gw_node_add() - add gateway node to list of available gateways 348 * @bat_priv: the bat priv with all the soft interface information 349 * @orig_node: originator announcing gateway capabilities 350 * @gateway: announced bandwidth information 351 */ 352 static void batadv_gw_node_add(struct batadv_priv *bat_priv, 353 struct batadv_orig_node *orig_node, 354 struct batadv_tvlv_gateway_data *gateway) 355 { 356 struct batadv_gw_node *gw_node; 357 358 if (gateway->bandwidth_down == 0) 359 return; 360 361 gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC); 362 if (!gw_node) 363 return; 364 365 kref_init(&gw_node->refcount); 366 INIT_HLIST_NODE(&gw_node->list); 367 kref_get(&orig_node->refcount); 368 gw_node->orig_node = orig_node; 369 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 370 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 371 372 spin_lock_bh(&bat_priv->gw.list_lock); 373 kref_get(&gw_node->refcount); 374 hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list); 375 spin_unlock_bh(&bat_priv->gw.list_lock); 376 377 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 378 "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n", 379 orig_node->orig, 380 ntohl(gateway->bandwidth_down) / 10, 381 ntohl(gateway->bandwidth_down) % 10, 382 ntohl(gateway->bandwidth_up) / 10, 383 ntohl(gateway->bandwidth_up) % 10); 384 385 /* don't return reference to new gw_node */ 386 batadv_gw_node_put(gw_node); 387 } 388 389 /** 390 * batadv_gw_node_get() - retrieve gateway node from list of available gateways 391 * @bat_priv: the bat priv with all the soft interface information 392 * @orig_node: originator announcing gateway capabilities 393 * 394 * Return: gateway node if found or NULL otherwise. 395 */ 396 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv, 397 struct batadv_orig_node *orig_node) 398 { 399 struct batadv_gw_node *gw_node_tmp, *gw_node = NULL; 400 401 rcu_read_lock(); 402 hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list, 403 list) { 404 if (gw_node_tmp->orig_node != orig_node) 405 continue; 406 407 if (!kref_get_unless_zero(&gw_node_tmp->refcount)) 408 continue; 409 410 gw_node = gw_node_tmp; 411 break; 412 } 413 rcu_read_unlock(); 414 415 return gw_node; 416 } 417 418 /** 419 * batadv_gw_node_update() - update list of available gateways with changed 420 * bandwidth information 421 * @bat_priv: the bat priv with all the soft interface information 422 * @orig_node: originator announcing gateway capabilities 423 * @gateway: announced bandwidth information 424 */ 425 void batadv_gw_node_update(struct batadv_priv *bat_priv, 426 struct batadv_orig_node *orig_node, 427 struct batadv_tvlv_gateway_data *gateway) 428 { 429 struct batadv_gw_node *gw_node, *curr_gw = NULL; 430 431 gw_node = batadv_gw_node_get(bat_priv, orig_node); 432 if (!gw_node) { 433 batadv_gw_node_add(bat_priv, orig_node, gateway); 434 goto out; 435 } 436 437 if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) && 438 gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)) 439 goto out; 440 441 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 442 "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n", 443 orig_node->orig, 444 gw_node->bandwidth_down / 10, 445 gw_node->bandwidth_down % 10, 446 gw_node->bandwidth_up / 10, 447 gw_node->bandwidth_up % 10, 448 ntohl(gateway->bandwidth_down) / 10, 449 ntohl(gateway->bandwidth_down) % 10, 450 ntohl(gateway->bandwidth_up) / 10, 451 ntohl(gateway->bandwidth_up) % 10); 452 453 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down); 454 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up); 455 456 if (ntohl(gateway->bandwidth_down) == 0) { 457 batadv_dbg(BATADV_DBG_BATMAN, bat_priv, 458 "Gateway %pM removed from gateway list\n", 459 orig_node->orig); 460 461 /* Note: We don't need a NULL check here, since curr_gw never 462 * gets dereferenced. 463 */ 464 spin_lock_bh(&bat_priv->gw.list_lock); 465 if (!hlist_unhashed(&gw_node->list)) { 466 hlist_del_init_rcu(&gw_node->list); 467 batadv_gw_node_put(gw_node); 468 } 469 spin_unlock_bh(&bat_priv->gw.list_lock); 470 471 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 472 if (gw_node == curr_gw) 473 batadv_gw_reselect(bat_priv); 474 475 if (curr_gw) 476 batadv_gw_node_put(curr_gw); 477 } 478 479 out: 480 if (gw_node) 481 batadv_gw_node_put(gw_node); 482 } 483 484 /** 485 * batadv_gw_node_delete() - Remove orig_node from gateway list 486 * @bat_priv: the bat priv with all the soft interface information 487 * @orig_node: orig node which is currently in process of being removed 488 */ 489 void batadv_gw_node_delete(struct batadv_priv *bat_priv, 490 struct batadv_orig_node *orig_node) 491 { 492 struct batadv_tvlv_gateway_data gateway; 493 494 gateway.bandwidth_down = 0; 495 gateway.bandwidth_up = 0; 496 497 batadv_gw_node_update(bat_priv, orig_node, &gateway); 498 } 499 500 /** 501 * batadv_gw_node_free() - Free gateway information from soft interface 502 * @bat_priv: the bat priv with all the soft interface information 503 */ 504 void batadv_gw_node_free(struct batadv_priv *bat_priv) 505 { 506 struct batadv_gw_node *gw_node; 507 struct hlist_node *node_tmp; 508 509 spin_lock_bh(&bat_priv->gw.list_lock); 510 hlist_for_each_entry_safe(gw_node, node_tmp, 511 &bat_priv->gw.gateway_list, list) { 512 hlist_del_init_rcu(&gw_node->list); 513 batadv_gw_node_put(gw_node); 514 } 515 spin_unlock_bh(&bat_priv->gw.list_lock); 516 } 517 518 #ifdef CONFIG_BATMAN_ADV_DEBUGFS 519 520 /** 521 * batadv_gw_client_seq_print_text() - Print the gateway table in a seq file 522 * @seq: seq file to print on 523 * @offset: not used 524 * 525 * Return: always 0 526 */ 527 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset) 528 { 529 struct net_device *net_dev = (struct net_device *)seq->private; 530 struct batadv_priv *bat_priv = netdev_priv(net_dev); 531 struct batadv_hard_iface *primary_if; 532 533 primary_if = batadv_seq_print_text_primary_if_get(seq); 534 if (!primary_if) 535 return 0; 536 537 seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n", 538 BATADV_SOURCE_VERSION, primary_if->net_dev->name, 539 primary_if->net_dev->dev_addr, net_dev->name, 540 bat_priv->algo_ops->name); 541 542 batadv_hardif_put(primary_if); 543 544 if (!bat_priv->algo_ops->gw.print) { 545 seq_puts(seq, 546 "No printing function for this routing protocol\n"); 547 return 0; 548 } 549 550 bat_priv->algo_ops->gw.print(bat_priv, seq); 551 552 return 0; 553 } 554 #endif 555 556 /** 557 * batadv_gw_dump() - Dump gateways into a message 558 * @msg: Netlink message to dump into 559 * @cb: Control block containing additional options 560 * 561 * Return: Error code, or length of message 562 */ 563 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb) 564 { 565 struct batadv_hard_iface *primary_if = NULL; 566 struct net *net = sock_net(cb->skb->sk); 567 struct net_device *soft_iface; 568 struct batadv_priv *bat_priv; 569 int ifindex; 570 int ret; 571 572 ifindex = batadv_netlink_get_ifindex(cb->nlh, 573 BATADV_ATTR_MESH_IFINDEX); 574 if (!ifindex) 575 return -EINVAL; 576 577 soft_iface = dev_get_by_index(net, ifindex); 578 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) { 579 ret = -ENODEV; 580 goto out; 581 } 582 583 bat_priv = netdev_priv(soft_iface); 584 585 primary_if = batadv_primary_if_get_selected(bat_priv); 586 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) { 587 ret = -ENOENT; 588 goto out; 589 } 590 591 if (!bat_priv->algo_ops->gw.dump) { 592 ret = -EOPNOTSUPP; 593 goto out; 594 } 595 596 bat_priv->algo_ops->gw.dump(msg, cb, bat_priv); 597 598 ret = msg->len; 599 600 out: 601 if (primary_if) 602 batadv_hardif_put(primary_if); 603 if (soft_iface) 604 dev_put(soft_iface); 605 606 return ret; 607 } 608 609 /** 610 * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message 611 * @skb: the packet to check 612 * @header_len: a pointer to the batman-adv header size 613 * @chaddr: buffer where the client address will be stored. Valid 614 * only if the function returns BATADV_DHCP_TO_CLIENT 615 * 616 * This function may re-allocate the data buffer of the skb passed as argument. 617 * 618 * Return: 619 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error 620 * while parsing it 621 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server 622 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client 623 */ 624 enum batadv_dhcp_recipient 625 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len, 626 u8 *chaddr) 627 { 628 enum batadv_dhcp_recipient ret = BATADV_DHCP_NO; 629 struct ethhdr *ethhdr; 630 struct iphdr *iphdr; 631 struct ipv6hdr *ipv6hdr; 632 struct udphdr *udphdr; 633 struct vlan_ethhdr *vhdr; 634 int chaddr_offset; 635 __be16 proto; 636 u8 *p; 637 638 /* check for ethernet header */ 639 if (!pskb_may_pull(skb, *header_len + ETH_HLEN)) 640 return BATADV_DHCP_NO; 641 642 ethhdr = eth_hdr(skb); 643 proto = ethhdr->h_proto; 644 *header_len += ETH_HLEN; 645 646 /* check for initial vlan header */ 647 if (proto == htons(ETH_P_8021Q)) { 648 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN)) 649 return BATADV_DHCP_NO; 650 651 vhdr = vlan_eth_hdr(skb); 652 proto = vhdr->h_vlan_encapsulated_proto; 653 *header_len += VLAN_HLEN; 654 } 655 656 /* check for ip header */ 657 switch (proto) { 658 case htons(ETH_P_IP): 659 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr))) 660 return BATADV_DHCP_NO; 661 662 iphdr = (struct iphdr *)(skb->data + *header_len); 663 *header_len += iphdr->ihl * 4; 664 665 /* check for udp header */ 666 if (iphdr->protocol != IPPROTO_UDP) 667 return BATADV_DHCP_NO; 668 669 break; 670 case htons(ETH_P_IPV6): 671 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr))) 672 return BATADV_DHCP_NO; 673 674 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len); 675 *header_len += sizeof(*ipv6hdr); 676 677 /* check for udp header */ 678 if (ipv6hdr->nexthdr != IPPROTO_UDP) 679 return BATADV_DHCP_NO; 680 681 break; 682 default: 683 return BATADV_DHCP_NO; 684 } 685 686 if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr))) 687 return BATADV_DHCP_NO; 688 689 udphdr = (struct udphdr *)(skb->data + *header_len); 690 *header_len += sizeof(*udphdr); 691 692 /* check for bootp port */ 693 switch (proto) { 694 case htons(ETH_P_IP): 695 if (udphdr->dest == htons(67)) 696 ret = BATADV_DHCP_TO_SERVER; 697 else if (udphdr->source == htons(67)) 698 ret = BATADV_DHCP_TO_CLIENT; 699 break; 700 case htons(ETH_P_IPV6): 701 if (udphdr->dest == htons(547)) 702 ret = BATADV_DHCP_TO_SERVER; 703 else if (udphdr->source == htons(547)) 704 ret = BATADV_DHCP_TO_CLIENT; 705 break; 706 } 707 708 chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET; 709 /* store the client address if the message is going to a client */ 710 if (ret == BATADV_DHCP_TO_CLIENT && 711 pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) { 712 /* check if the DHCP packet carries an Ethernet DHCP */ 713 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET; 714 if (*p != BATADV_DHCP_HTYPE_ETHERNET) 715 return BATADV_DHCP_NO; 716 717 /* check if the DHCP packet carries a valid Ethernet address */ 718 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET; 719 if (*p != ETH_ALEN) 720 return BATADV_DHCP_NO; 721 722 ether_addr_copy(chaddr, skb->data + chaddr_offset); 723 } 724 725 return ret; 726 } 727 728 /** 729 * batadv_gw_out_of_range() - check if the dhcp request destination is the best 730 * gateway 731 * @bat_priv: the bat priv with all the soft interface information 732 * @skb: the outgoing packet 733 * 734 * Check if the skb is a DHCP request and if it is sent to the current best GW 735 * server. Due to topology changes it may be the case that the GW server 736 * previously selected is not the best one anymore. 737 * 738 * This call might reallocate skb data. 739 * Must be invoked only when the DHCP packet is going TO a DHCP SERVER. 740 * 741 * Return: true if the packet destination is unicast and it is not the best gw, 742 * false otherwise. 743 */ 744 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv, 745 struct sk_buff *skb) 746 { 747 struct batadv_neigh_node *neigh_curr = NULL; 748 struct batadv_neigh_node *neigh_old = NULL; 749 struct batadv_orig_node *orig_dst_node; 750 struct batadv_gw_node *gw_node = NULL; 751 struct batadv_gw_node *curr_gw = NULL; 752 struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo; 753 struct ethhdr *ethhdr = (struct ethhdr *)skb->data; 754 bool out_of_range = false; 755 u8 curr_tq_avg; 756 unsigned short vid; 757 758 vid = batadv_get_vid(skb, 0); 759 760 orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source, 761 ethhdr->h_dest, vid); 762 if (!orig_dst_node) 763 goto out; 764 765 gw_node = batadv_gw_node_get(bat_priv, orig_dst_node); 766 if (!gw_node) 767 goto out; 768 769 switch (atomic_read(&bat_priv->gw.mode)) { 770 case BATADV_GW_MODE_SERVER: 771 /* If we are a GW then we are our best GW. We can artificially 772 * set the tq towards ourself as the maximum value 773 */ 774 curr_tq_avg = BATADV_TQ_MAX_VALUE; 775 break; 776 case BATADV_GW_MODE_CLIENT: 777 curr_gw = batadv_gw_get_selected_gw_node(bat_priv); 778 if (!curr_gw) 779 goto out; 780 781 /* packet is going to our gateway */ 782 if (curr_gw->orig_node == orig_dst_node) 783 goto out; 784 785 /* If the dhcp packet has been sent to a different gw, 786 * we have to evaluate whether the old gw is still 787 * reliable enough 788 */ 789 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node, 790 NULL); 791 if (!neigh_curr) 792 goto out; 793 794 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr, 795 BATADV_IF_DEFAULT); 796 if (!curr_ifinfo) 797 goto out; 798 799 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg; 800 batadv_neigh_ifinfo_put(curr_ifinfo); 801 802 break; 803 case BATADV_GW_MODE_OFF: 804 default: 805 goto out; 806 } 807 808 neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL); 809 if (!neigh_old) 810 goto out; 811 812 old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT); 813 if (!old_ifinfo) 814 goto out; 815 816 if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD) 817 out_of_range = true; 818 batadv_neigh_ifinfo_put(old_ifinfo); 819 820 out: 821 if (orig_dst_node) 822 batadv_orig_node_put(orig_dst_node); 823 if (curr_gw) 824 batadv_gw_node_put(curr_gw); 825 if (gw_node) 826 batadv_gw_node_put(gw_node); 827 if (neigh_old) 828 batadv_neigh_node_put(neigh_old); 829 if (neigh_curr) 830 batadv_neigh_node_put(neigh_curr); 831 return out_of_range; 832 } 833