1/* 2 * Handle firewalling 3 * Linux ethernet bridge 4 * 5 * Authors: 6 * Lennert Buytenhek <buytenh@gnu.org> 7 * Bart De Schuymer <bdschuym@pandora.be> 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; either version 12 * 2 of the License, or (at your option) any later version. 13 * 14 * Lennert dedicates this file to Kerstin Wurdinger. 15 */ 16 17#include <linux/module.h> 18#include <linux/kernel.h> 19#include <linux/slab.h> 20#include <linux/ip.h> 21#include <linux/netdevice.h> 22#include <linux/skbuff.h> 23#include <linux/if_arp.h> 24#include <linux/if_ether.h> 25#include <linux/if_vlan.h> 26#include <linux/if_pppox.h> 27#include <linux/ppp_defs.h> 28#include <linux/netfilter_bridge.h> 29#include <linux/netfilter_ipv4.h> 30#include <linux/netfilter_ipv6.h> 31#include <linux/netfilter_arp.h> 32#include <linux/in_route.h> 33#include <linux/inetdevice.h> 34 35#include <net/ip.h> 36#include <net/ipv6.h> 37#include <net/addrconf.h> 38#include <net/route.h> 39#include <net/netfilter/br_netfilter.h> 40 41#include <asm/uaccess.h> 42#include "br_private.h" 43#ifdef CONFIG_SYSCTL 44#include <linux/sysctl.h> 45#endif 46 47#ifdef CONFIG_SYSCTL 48static struct ctl_table_header *brnf_sysctl_header; 49static int brnf_call_iptables __read_mostly = 1; 50static int brnf_call_ip6tables __read_mostly = 1; 51static int brnf_call_arptables __read_mostly = 1; 52static int brnf_filter_vlan_tagged __read_mostly; 53static int brnf_filter_pppoe_tagged __read_mostly; 54static int brnf_pass_vlan_indev __read_mostly; 55#else 56#define brnf_call_iptables 1 57#define brnf_call_ip6tables 1 58#define brnf_call_arptables 1 59#define brnf_filter_vlan_tagged 0 60#define brnf_filter_pppoe_tagged 0 61#define brnf_pass_vlan_indev 0 62#endif 63 64#define IS_IP(skb) \ 65 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP)) 66 67#define IS_IPV6(skb) \ 68 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6)) 69 70#define IS_ARP(skb) \ 71 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP)) 72 73static inline __be16 vlan_proto(const struct sk_buff *skb) 74{ 75 if (skb_vlan_tag_present(skb)) 76 return skb->protocol; 77 else if (skb->protocol == htons(ETH_P_8021Q)) 78 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto; 79 else 80 return 0; 81} 82 83#define IS_VLAN_IP(skb) \ 84 (vlan_proto(skb) == htons(ETH_P_IP) && \ 85 brnf_filter_vlan_tagged) 86 87#define IS_VLAN_IPV6(skb) \ 88 (vlan_proto(skb) == htons(ETH_P_IPV6) && \ 89 brnf_filter_vlan_tagged) 90 91#define IS_VLAN_ARP(skb) \ 92 (vlan_proto(skb) == htons(ETH_P_ARP) && \ 93 brnf_filter_vlan_tagged) 94 95static inline __be16 pppoe_proto(const struct sk_buff *skb) 96{ 97 return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN + 98 sizeof(struct pppoe_hdr))); 99} 100 101#define IS_PPPOE_IP(skb) \ 102 (skb->protocol == htons(ETH_P_PPP_SES) && \ 103 pppoe_proto(skb) == htons(PPP_IP) && \ 104 brnf_filter_pppoe_tagged) 105 106#define IS_PPPOE_IPV6(skb) \ 107 (skb->protocol == htons(ETH_P_PPP_SES) && \ 108 pppoe_proto(skb) == htons(PPP_IPV6) && \ 109 brnf_filter_pppoe_tagged) 110 111/* largest possible L2 header, see br_nf_dev_queue_xmit() */ 112#define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN) 113 114struct brnf_frag_data { 115 char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH]; 116 u8 encap_size; 117 u8 size; 118 u16 vlan_tci; 119 __be16 vlan_proto; 120}; 121 122static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage); 123 124static void nf_bridge_info_free(struct sk_buff *skb) 125{ 126 if (skb->nf_bridge) { 127 nf_bridge_put(skb->nf_bridge); 128 skb->nf_bridge = NULL; 129 } 130} 131 132static inline struct net_device *bridge_parent(const struct net_device *dev) 133{ 134 struct net_bridge_port *port; 135 136 port = br_port_get_rcu(dev); 137 return port ? port->br->dev : NULL; 138} 139 140static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb) 141{ 142 struct nf_bridge_info *nf_bridge = skb->nf_bridge; 143 144 if (atomic_read(&nf_bridge->use) > 1) { 145 struct nf_bridge_info *tmp = nf_bridge_alloc(skb); 146 147 if (tmp) { 148 memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info)); 149 atomic_set(&tmp->use, 1); 150 } 151 nf_bridge_put(nf_bridge); 152 nf_bridge = tmp; 153 } 154 return nf_bridge; 155} 156 157unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb) 158{ 159 switch (skb->protocol) { 160 case __cpu_to_be16(ETH_P_8021Q): 161 return VLAN_HLEN; 162 case __cpu_to_be16(ETH_P_PPP_SES): 163 return PPPOE_SES_HLEN; 164 default: 165 return 0; 166 } 167} 168 169static inline void nf_bridge_pull_encap_header(struct sk_buff *skb) 170{ 171 unsigned int len = nf_bridge_encap_header_len(skb); 172 173 skb_pull(skb, len); 174 skb->network_header += len; 175} 176 177static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb) 178{ 179 unsigned int len = nf_bridge_encap_header_len(skb); 180 181 skb_pull_rcsum(skb, len); 182 skb->network_header += len; 183} 184 185/* When handing a packet over to the IP layer 186 * check whether we have a skb that is in the 187 * expected format 188 */ 189 190static int br_validate_ipv4(struct net *net, struct sk_buff *skb) 191{ 192 const struct iphdr *iph; 193 u32 len; 194 195 if (!pskb_may_pull(skb, sizeof(struct iphdr))) 196 goto inhdr_error; 197 198 iph = ip_hdr(skb); 199 200 /* Basic sanity checks */ 201 if (iph->ihl < 5 || iph->version != 4) 202 goto inhdr_error; 203 204 if (!pskb_may_pull(skb, iph->ihl*4)) 205 goto inhdr_error; 206 207 iph = ip_hdr(skb); 208 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl))) 209 goto inhdr_error; 210 211 len = ntohs(iph->tot_len); 212 if (skb->len < len) { 213 IP_INC_STATS_BH(net, IPSTATS_MIB_INTRUNCATEDPKTS); 214 goto drop; 215 } else if (len < (iph->ihl*4)) 216 goto inhdr_error; 217 218 if (pskb_trim_rcsum(skb, len)) { 219 IP_INC_STATS_BH(net, IPSTATS_MIB_INDISCARDS); 220 goto drop; 221 } 222 223 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); 224 /* We should really parse IP options here but until 225 * somebody who actually uses IP options complains to 226 * us we'll just silently ignore the options because 227 * we're lazy! 228 */ 229 return 0; 230 231inhdr_error: 232 IP_INC_STATS_BH(net, IPSTATS_MIB_INHDRERRORS); 233drop: 234 return -1; 235} 236 237void nf_bridge_update_protocol(struct sk_buff *skb) 238{ 239 switch (skb->nf_bridge->orig_proto) { 240 case BRNF_PROTO_8021Q: 241 skb->protocol = htons(ETH_P_8021Q); 242 break; 243 case BRNF_PROTO_PPPOE: 244 skb->protocol = htons(ETH_P_PPP_SES); 245 break; 246 case BRNF_PROTO_UNCHANGED: 247 break; 248 } 249} 250 251/* Obtain the correct destination MAC address, while preserving the original 252 * source MAC address. If we already know this address, we just copy it. If we 253 * don't, we use the neighbour framework to find out. In both cases, we make 254 * sure that br_handle_frame_finish() is called afterwards. 255 */ 256int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb) 257{ 258 struct neighbour *neigh; 259 struct dst_entry *dst; 260 261 skb->dev = bridge_parent(skb->dev); 262 if (!skb->dev) 263 goto free_skb; 264 dst = skb_dst(skb); 265 neigh = dst_neigh_lookup_skb(dst, skb); 266 if (neigh) { 267 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 268 int ret; 269 270 if (neigh->hh.hh_len) { 271 neigh_hh_bridge(&neigh->hh, skb); 272 skb->dev = nf_bridge->physindev; 273 ret = br_handle_frame_finish(net, sk, skb); 274 } else { 275 /* the neighbour function below overwrites the complete 276 * MAC header, so we save the Ethernet source address and 277 * protocol number. 278 */ 279 skb_copy_from_linear_data_offset(skb, 280 -(ETH_HLEN-ETH_ALEN), 281 nf_bridge->neigh_header, 282 ETH_HLEN-ETH_ALEN); 283 /* tell br_dev_xmit to continue with forwarding */ 284 nf_bridge->bridged_dnat = 1; 285 /* FIXME Need to refragment */ 286 ret = neigh->output(neigh, skb); 287 } 288 neigh_release(neigh); 289 return ret; 290 } 291free_skb: 292 kfree_skb(skb); 293 return 0; 294} 295 296static inline bool 297br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb, 298 const struct nf_bridge_info *nf_bridge) 299{ 300 return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr; 301} 302 303/* This requires some explaining. If DNAT has taken place, 304 * we will need to fix up the destination Ethernet address. 305 * This is also true when SNAT takes place (for the reply direction). 306 * 307 * There are two cases to consider: 308 * 1. The packet was DNAT'ed to a device in the same bridge 309 * port group as it was received on. We can still bridge 310 * the packet. 311 * 2. The packet was DNAT'ed to a different device, either 312 * a non-bridged device or another bridge port group. 313 * The packet will need to be routed. 314 * 315 * The correct way of distinguishing between these two cases is to 316 * call ip_route_input() and to look at skb->dst->dev, which is 317 * changed to the destination device if ip_route_input() succeeds. 318 * 319 * Let's first consider the case that ip_route_input() succeeds: 320 * 321 * If the output device equals the logical bridge device the packet 322 * came in on, we can consider this bridging. The corresponding MAC 323 * address will be obtained in br_nf_pre_routing_finish_bridge. 324 * Otherwise, the packet is considered to be routed and we just 325 * change the destination MAC address so that the packet will 326 * later be passed up to the IP stack to be routed. For a redirected 327 * packet, ip_route_input() will give back the localhost as output device, 328 * which differs from the bridge device. 329 * 330 * Let's now consider the case that ip_route_input() fails: 331 * 332 * This can be because the destination address is martian, in which case 333 * the packet will be dropped. 334 * If IP forwarding is disabled, ip_route_input() will fail, while 335 * ip_route_output_key() can return success. The source 336 * address for ip_route_output_key() is set to zero, so ip_route_output_key() 337 * thinks we're handling a locally generated packet and won't care 338 * if IP forwarding is enabled. If the output device equals the logical bridge 339 * device, we proceed as if ip_route_input() succeeded. If it differs from the 340 * logical bridge port or if ip_route_output_key() fails we drop the packet. 341 */ 342static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 343{ 344 struct net_device *dev = skb->dev; 345 struct iphdr *iph = ip_hdr(skb); 346 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 347 struct rtable *rt; 348 int err; 349 350 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size; 351 352 if (nf_bridge->pkt_otherhost) { 353 skb->pkt_type = PACKET_OTHERHOST; 354 nf_bridge->pkt_otherhost = false; 355 } 356 nf_bridge->in_prerouting = 0; 357 if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) { 358 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) { 359 struct in_device *in_dev = __in_dev_get_rcu(dev); 360 361 /* If err equals -EHOSTUNREACH the error is due to a 362 * martian destination or due to the fact that 363 * forwarding is disabled. For most martian packets, 364 * ip_route_output_key() will fail. It won't fail for 2 types of 365 * martian destinations: loopback destinations and destination 366 * 0.0.0.0. In both cases the packet will be dropped because the 367 * destination is the loopback device and not the bridge. */ 368 if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev)) 369 goto free_skb; 370 371 rt = ip_route_output(net, iph->daddr, 0, 372 RT_TOS(iph->tos), 0); 373 if (!IS_ERR(rt)) { 374 /* - Bridged-and-DNAT'ed traffic doesn't 375 * require ip_forwarding. */ 376 if (rt->dst.dev == dev) { 377 skb_dst_set(skb, &rt->dst); 378 goto bridged_dnat; 379 } 380 ip_rt_put(rt); 381 } 382free_skb: 383 kfree_skb(skb); 384 return 0; 385 } else { 386 if (skb_dst(skb)->dev == dev) { 387bridged_dnat: 388 skb->dev = nf_bridge->physindev; 389 nf_bridge_update_protocol(skb); 390 nf_bridge_push_encap_header(skb); 391 NF_HOOK_THRESH(NFPROTO_BRIDGE, 392 NF_BR_PRE_ROUTING, 393 net, sk, skb, skb->dev, NULL, 394 br_nf_pre_routing_finish_bridge, 395 1); 396 return 0; 397 } 398 ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr); 399 skb->pkt_type = PACKET_HOST; 400 } 401 } else { 402 rt = bridge_parent_rtable(nf_bridge->physindev); 403 if (!rt) { 404 kfree_skb(skb); 405 return 0; 406 } 407 skb_dst_set_noref(skb, &rt->dst); 408 } 409 410 skb->dev = nf_bridge->physindev; 411 nf_bridge_update_protocol(skb); 412 nf_bridge_push_encap_header(skb); 413 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, net, sk, skb, 414 skb->dev, NULL, 415 br_handle_frame_finish, 1); 416 417 return 0; 418} 419 420static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev) 421{ 422 struct net_device *vlan, *br; 423 424 br = bridge_parent(dev); 425 if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb)) 426 return br; 427 428 vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto, 429 skb_vlan_tag_get(skb) & VLAN_VID_MASK); 430 431 return vlan ? vlan : br; 432} 433 434/* Some common code for IPv4/IPv6 */ 435struct net_device *setup_pre_routing(struct sk_buff *skb) 436{ 437 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 438 439 if (skb->pkt_type == PACKET_OTHERHOST) { 440 skb->pkt_type = PACKET_HOST; 441 nf_bridge->pkt_otherhost = true; 442 } 443 444 nf_bridge->in_prerouting = 1; 445 nf_bridge->physindev = skb->dev; 446 skb->dev = brnf_get_logical_dev(skb, skb->dev); 447 448 if (skb->protocol == htons(ETH_P_8021Q)) 449 nf_bridge->orig_proto = BRNF_PROTO_8021Q; 450 else if (skb->protocol == htons(ETH_P_PPP_SES)) 451 nf_bridge->orig_proto = BRNF_PROTO_PPPOE; 452 453 /* Must drop socket now because of tproxy. */ 454 skb_orphan(skb); 455 return skb->dev; 456} 457 458/* Direct IPv6 traffic to br_nf_pre_routing_ipv6. 459 * Replicate the checks that IPv4 does on packet reception. 460 * Set skb->dev to the bridge device (i.e. parent of the 461 * receiving device) to make netfilter happy, the REDIRECT 462 * target in particular. Save the original destination IP 463 * address to be able to detect DNAT afterwards. */ 464static unsigned int br_nf_pre_routing(void *priv, 465 struct sk_buff *skb, 466 const struct nf_hook_state *state) 467{ 468 struct nf_bridge_info *nf_bridge; 469 struct net_bridge_port *p; 470 struct net_bridge *br; 471 __u32 len = nf_bridge_encap_header_len(skb); 472 473 if (unlikely(!pskb_may_pull(skb, len))) 474 return NF_DROP; 475 476 p = br_port_get_rcu(state->in); 477 if (p == NULL) 478 return NF_DROP; 479 br = p->br; 480 481 if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) { 482 if (!brnf_call_ip6tables && !br->nf_call_ip6tables) 483 return NF_ACCEPT; 484 485 nf_bridge_pull_encap_header_rcsum(skb); 486 return br_nf_pre_routing_ipv6(priv, skb, state); 487 } 488 489 if (!brnf_call_iptables && !br->nf_call_iptables) 490 return NF_ACCEPT; 491 492 if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb)) 493 return NF_ACCEPT; 494 495 nf_bridge_pull_encap_header_rcsum(skb); 496 497 if (br_validate_ipv4(state->net, skb)) 498 return NF_DROP; 499 500 nf_bridge_put(skb->nf_bridge); 501 if (!nf_bridge_alloc(skb)) 502 return NF_DROP; 503 if (!setup_pre_routing(skb)) 504 return NF_DROP; 505 506 nf_bridge = nf_bridge_info_get(skb); 507 nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr; 508 509 skb->protocol = htons(ETH_P_IP); 510 511 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb, 512 skb->dev, NULL, 513 br_nf_pre_routing_finish); 514 515 return NF_STOLEN; 516} 517 518 519/* PF_BRIDGE/LOCAL_IN ************************************************/ 520/* The packet is locally destined, which requires a real 521 * dst_entry, so detach the fake one. On the way up, the 522 * packet would pass through PRE_ROUTING again (which already 523 * took place when the packet entered the bridge), but we 524 * register an IPv4 PRE_ROUTING 'sabotage' hook that will 525 * prevent this from happening. */ 526static unsigned int br_nf_local_in(void *priv, 527 struct sk_buff *skb, 528 const struct nf_hook_state *state) 529{ 530 br_drop_fake_rtable(skb); 531 return NF_ACCEPT; 532} 533 534/* PF_BRIDGE/FORWARD *************************************************/ 535static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb) 536{ 537 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 538 struct net_device *in; 539 540 if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) { 541 542 if (skb->protocol == htons(ETH_P_IP)) 543 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size; 544 545 if (skb->protocol == htons(ETH_P_IPV6)) 546 nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size; 547 548 in = nf_bridge->physindev; 549 if (nf_bridge->pkt_otherhost) { 550 skb->pkt_type = PACKET_OTHERHOST; 551 nf_bridge->pkt_otherhost = false; 552 } 553 nf_bridge_update_protocol(skb); 554 } else { 555 in = *((struct net_device **)(skb->cb)); 556 } 557 nf_bridge_push_encap_header(skb); 558 559 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, net, sk, skb, 560 in, skb->dev, br_forward_finish, 1); 561 return 0; 562} 563 564 565/* This is the 'purely bridged' case. For IP, we pass the packet to 566 * netfilter with indev and outdev set to the bridge device, 567 * but we are still able to filter on the 'real' indev/outdev 568 * because of the physdev module. For ARP, indev and outdev are the 569 * bridge ports. */ 570static unsigned int br_nf_forward_ip(void *priv, 571 struct sk_buff *skb, 572 const struct nf_hook_state *state) 573{ 574 struct nf_bridge_info *nf_bridge; 575 struct net_device *parent; 576 u_int8_t pf; 577 578 if (!skb->nf_bridge) 579 return NF_ACCEPT; 580 581 /* Need exclusive nf_bridge_info since we might have multiple 582 * different physoutdevs. */ 583 if (!nf_bridge_unshare(skb)) 584 return NF_DROP; 585 586 nf_bridge = nf_bridge_info_get(skb); 587 if (!nf_bridge) 588 return NF_DROP; 589 590 parent = bridge_parent(state->out); 591 if (!parent) 592 return NF_DROP; 593 594 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) 595 pf = NFPROTO_IPV4; 596 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) 597 pf = NFPROTO_IPV6; 598 else 599 return NF_ACCEPT; 600 601 nf_bridge_pull_encap_header(skb); 602 603 if (skb->pkt_type == PACKET_OTHERHOST) { 604 skb->pkt_type = PACKET_HOST; 605 nf_bridge->pkt_otherhost = true; 606 } 607 608 if (pf == NFPROTO_IPV4) { 609 if (br_validate_ipv4(state->net, skb)) 610 return NF_DROP; 611 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; 612 } 613 614 if (pf == NFPROTO_IPV6) { 615 if (br_validate_ipv6(state->net, skb)) 616 return NF_DROP; 617 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size; 618 } 619 620 nf_bridge->physoutdev = skb->dev; 621 if (pf == NFPROTO_IPV4) 622 skb->protocol = htons(ETH_P_IP); 623 else 624 skb->protocol = htons(ETH_P_IPV6); 625 626 NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb, 627 brnf_get_logical_dev(skb, state->in), 628 parent, br_nf_forward_finish); 629 630 return NF_STOLEN; 631} 632 633static unsigned int br_nf_forward_arp(void *priv, 634 struct sk_buff *skb, 635 const struct nf_hook_state *state) 636{ 637 struct net_bridge_port *p; 638 struct net_bridge *br; 639 struct net_device **d = (struct net_device **)(skb->cb); 640 641 p = br_port_get_rcu(state->out); 642 if (p == NULL) 643 return NF_ACCEPT; 644 br = p->br; 645 646 if (!brnf_call_arptables && !br->nf_call_arptables) 647 return NF_ACCEPT; 648 649 if (!IS_ARP(skb)) { 650 if (!IS_VLAN_ARP(skb)) 651 return NF_ACCEPT; 652 nf_bridge_pull_encap_header(skb); 653 } 654 655 if (arp_hdr(skb)->ar_pln != 4) { 656 if (IS_VLAN_ARP(skb)) 657 nf_bridge_push_encap_header(skb); 658 return NF_ACCEPT; 659 } 660 *d = state->in; 661 NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb, 662 state->in, state->out, br_nf_forward_finish); 663 664 return NF_STOLEN; 665} 666 667static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 668{ 669 struct brnf_frag_data *data; 670 int err; 671 672 data = this_cpu_ptr(&brnf_frag_data_storage); 673 err = skb_cow_head(skb, data->size); 674 675 if (err) { 676 kfree_skb(skb); 677 return 0; 678 } 679 680 if (data->vlan_tci) { 681 skb->vlan_tci = data->vlan_tci; 682 skb->vlan_proto = data->vlan_proto; 683 } 684 685 skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size); 686 __skb_push(skb, data->encap_size); 687 688 nf_bridge_info_free(skb); 689 return br_dev_queue_push_xmit(net, sk, skb); 690} 691 692static int 693br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, 694 int (*output)(struct net *, struct sock *, struct sk_buff *)) 695{ 696 unsigned int mtu = ip_skb_dst_mtu(skb); 697 struct iphdr *iph = ip_hdr(skb); 698 699 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) || 700 (IPCB(skb)->frag_max_size && 701 IPCB(skb)->frag_max_size > mtu))) { 702 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS); 703 kfree_skb(skb); 704 return -EMSGSIZE; 705 } 706 707 return ip_do_fragment(net, sk, skb, output); 708} 709 710static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb) 711{ 712 if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE) 713 return PPPOE_SES_HLEN; 714 return 0; 715} 716 717static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb) 718{ 719 struct nf_bridge_info *nf_bridge; 720 unsigned int mtu_reserved; 721 722 mtu_reserved = nf_bridge_mtu_reduction(skb); 723 724 if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) { 725 nf_bridge_info_free(skb); 726 return br_dev_queue_push_xmit(net, sk, skb); 727 } 728 729 nf_bridge = nf_bridge_info_get(skb); 730 731 /* This is wrong! We should preserve the original fragment 732 * boundaries by preserving frag_list rather than refragmenting. 733 */ 734 if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) && 735 skb->protocol == htons(ETH_P_IP)) { 736 struct brnf_frag_data *data; 737 738 if (br_validate_ipv4(net, skb)) 739 goto drop; 740 741 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size; 742 743 nf_bridge_update_protocol(skb); 744 745 data = this_cpu_ptr(&brnf_frag_data_storage); 746 747 data->vlan_tci = skb->vlan_tci; 748 data->vlan_proto = skb->vlan_proto; 749 data->encap_size = nf_bridge_encap_header_len(skb); 750 data->size = ETH_HLEN + data->encap_size; 751 752 skb_copy_from_linear_data_offset(skb, -data->size, data->mac, 753 data->size); 754 755 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit); 756 } 757 if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) && 758 skb->protocol == htons(ETH_P_IPV6)) { 759 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops(); 760 struct brnf_frag_data *data; 761 762 if (br_validate_ipv6(net, skb)) 763 goto drop; 764 765 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size; 766 767 nf_bridge_update_protocol(skb); 768 769 data = this_cpu_ptr(&brnf_frag_data_storage); 770 data->encap_size = nf_bridge_encap_header_len(skb); 771 data->size = ETH_HLEN + data->encap_size; 772 773 skb_copy_from_linear_data_offset(skb, -data->size, data->mac, 774 data->size); 775 776 if (v6ops) 777 return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit); 778 779 kfree_skb(skb); 780 return -EMSGSIZE; 781 } 782 nf_bridge_info_free(skb); 783 return br_dev_queue_push_xmit(net, sk, skb); 784 drop: 785 kfree_skb(skb); 786 return 0; 787} 788 789/* PF_BRIDGE/POST_ROUTING ********************************************/ 790static unsigned int br_nf_post_routing(void *priv, 791 struct sk_buff *skb, 792 const struct nf_hook_state *state) 793{ 794 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 795 struct net_device *realoutdev = bridge_parent(skb->dev); 796 u_int8_t pf; 797 798 /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in 799 * on a bridge, but was delivered locally and is now being routed: 800 * 801 * POST_ROUTING was already invoked from the ip stack. 802 */ 803 if (!nf_bridge || !nf_bridge->physoutdev) 804 return NF_ACCEPT; 805 806 if (!realoutdev) 807 return NF_DROP; 808 809 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb)) 810 pf = NFPROTO_IPV4; 811 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) 812 pf = NFPROTO_IPV6; 813 else 814 return NF_ACCEPT; 815 816 /* We assume any code from br_dev_queue_push_xmit onwards doesn't care 817 * about the value of skb->pkt_type. */ 818 if (skb->pkt_type == PACKET_OTHERHOST) { 819 skb->pkt_type = PACKET_HOST; 820 nf_bridge->pkt_otherhost = true; 821 } 822 823 nf_bridge_pull_encap_header(skb); 824 if (pf == NFPROTO_IPV4) 825 skb->protocol = htons(ETH_P_IP); 826 else 827 skb->protocol = htons(ETH_P_IPV6); 828 829 NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb, 830 NULL, realoutdev, 831 br_nf_dev_queue_xmit); 832 833 return NF_STOLEN; 834} 835 836/* IP/SABOTAGE *****************************************************/ 837/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING 838 * for the second time. */ 839static unsigned int ip_sabotage_in(void *priv, 840 struct sk_buff *skb, 841 const struct nf_hook_state *state) 842{ 843 if (skb->nf_bridge && !skb->nf_bridge->in_prerouting) 844 return NF_STOP; 845 846 return NF_ACCEPT; 847} 848 849/* This is called when br_netfilter has called into iptables/netfilter, 850 * and DNAT has taken place on a bridge-forwarded packet. 851 * 852 * neigh->output has created a new MAC header, with local br0 MAC 853 * as saddr. 854 * 855 * This restores the original MAC saddr of the bridged packet 856 * before invoking bridge forward logic to transmit the packet. 857 */ 858static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb) 859{ 860 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb); 861 862 skb_pull(skb, ETH_HLEN); 863 nf_bridge->bridged_dnat = 0; 864 865 BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN)); 866 867 skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN), 868 nf_bridge->neigh_header, 869 ETH_HLEN - ETH_ALEN); 870 skb->dev = nf_bridge->physindev; 871 872 nf_bridge->physoutdev = NULL; 873 br_handle_frame_finish(dev_net(skb->dev), NULL, skb); 874} 875 876static int br_nf_dev_xmit(struct sk_buff *skb) 877{ 878 if (skb->nf_bridge && skb->nf_bridge->bridged_dnat) { 879 br_nf_pre_routing_finish_bridge_slow(skb); 880 return 1; 881 } 882 return 0; 883} 884 885static const struct nf_br_ops br_ops = { 886 .br_dev_xmit_hook = br_nf_dev_xmit, 887}; 888 889void br_netfilter_enable(void) 890{ 891} 892EXPORT_SYMBOL_GPL(br_netfilter_enable); 893 894/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because 895 * br_dev_queue_push_xmit is called afterwards */ 896static struct nf_hook_ops br_nf_ops[] __read_mostly = { 897 { 898 .hook = br_nf_pre_routing, 899 .pf = NFPROTO_BRIDGE, 900 .hooknum = NF_BR_PRE_ROUTING, 901 .priority = NF_BR_PRI_BRNF, 902 }, 903 { 904 .hook = br_nf_local_in, 905 .pf = NFPROTO_BRIDGE, 906 .hooknum = NF_BR_LOCAL_IN, 907 .priority = NF_BR_PRI_BRNF, 908 }, 909 { 910 .hook = br_nf_forward_ip, 911 .pf = NFPROTO_BRIDGE, 912 .hooknum = NF_BR_FORWARD, 913 .priority = NF_BR_PRI_BRNF - 1, 914 }, 915 { 916 .hook = br_nf_forward_arp, 917 .pf = NFPROTO_BRIDGE, 918 .hooknum = NF_BR_FORWARD, 919 .priority = NF_BR_PRI_BRNF, 920 }, 921 { 922 .hook = br_nf_post_routing, 923 .pf = NFPROTO_BRIDGE, 924 .hooknum = NF_BR_POST_ROUTING, 925 .priority = NF_BR_PRI_LAST, 926 }, 927 { 928 .hook = ip_sabotage_in, 929 .pf = NFPROTO_IPV4, 930 .hooknum = NF_INET_PRE_ROUTING, 931 .priority = NF_IP_PRI_FIRST, 932 }, 933 { 934 .hook = ip_sabotage_in, 935 .pf = NFPROTO_IPV6, 936 .hooknum = NF_INET_PRE_ROUTING, 937 .priority = NF_IP6_PRI_FIRST, 938 }, 939}; 940 941#ifdef CONFIG_SYSCTL 942static 943int brnf_sysctl_call_tables(struct ctl_table *ctl, int write, 944 void __user *buffer, size_t *lenp, loff_t *ppos) 945{ 946 int ret; 947 948 ret = proc_dointvec(ctl, write, buffer, lenp, ppos); 949 950 if (write && *(int *)(ctl->data)) 951 *(int *)(ctl->data) = 1; 952 return ret; 953} 954 955static struct ctl_table brnf_table[] = { 956 { 957 .procname = "bridge-nf-call-arptables", 958 .data = &brnf_call_arptables, 959 .maxlen = sizeof(int), 960 .mode = 0644, 961 .proc_handler = brnf_sysctl_call_tables, 962 }, 963 { 964 .procname = "bridge-nf-call-iptables", 965 .data = &brnf_call_iptables, 966 .maxlen = sizeof(int), 967 .mode = 0644, 968 .proc_handler = brnf_sysctl_call_tables, 969 }, 970 { 971 .procname = "bridge-nf-call-ip6tables", 972 .data = &brnf_call_ip6tables, 973 .maxlen = sizeof(int), 974 .mode = 0644, 975 .proc_handler = brnf_sysctl_call_tables, 976 }, 977 { 978 .procname = "bridge-nf-filter-vlan-tagged", 979 .data = &brnf_filter_vlan_tagged, 980 .maxlen = sizeof(int), 981 .mode = 0644, 982 .proc_handler = brnf_sysctl_call_tables, 983 }, 984 { 985 .procname = "bridge-nf-filter-pppoe-tagged", 986 .data = &brnf_filter_pppoe_tagged, 987 .maxlen = sizeof(int), 988 .mode = 0644, 989 .proc_handler = brnf_sysctl_call_tables, 990 }, 991 { 992 .procname = "bridge-nf-pass-vlan-input-dev", 993 .data = &brnf_pass_vlan_indev, 994 .maxlen = sizeof(int), 995 .mode = 0644, 996 .proc_handler = brnf_sysctl_call_tables, 997 }, 998 { } 999}; 1000#endif 1001 1002static int __init br_netfilter_init(void) 1003{ 1004 int ret; 1005 1006 ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); 1007 if (ret < 0) 1008 return ret; 1009 1010#ifdef CONFIG_SYSCTL 1011 brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table); 1012 if (brnf_sysctl_header == NULL) { 1013 printk(KERN_WARNING 1014 "br_netfilter: can't register to sysctl.\n"); 1015 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); 1016 return -ENOMEM; 1017 } 1018#endif 1019 RCU_INIT_POINTER(nf_br_ops, &br_ops); 1020 printk(KERN_NOTICE "Bridge firewalling registered\n"); 1021 return 0; 1022} 1023 1024static void __exit br_netfilter_fini(void) 1025{ 1026 RCU_INIT_POINTER(nf_br_ops, NULL); 1027 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); 1028#ifdef CONFIG_SYSCTL 1029 unregister_net_sysctl_table(brnf_sysctl_header); 1030#endif 1031} 1032 1033module_init(br_netfilter_init); 1034module_exit(br_netfilter_fini); 1035 1036MODULE_LICENSE("GPL"); 1037MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>"); 1038MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); 1039MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge"); 1040