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   1 /*
   2  *      Handle firewalling
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *      Bart De Schuymer (maintainer)   <bdschuym@pandora.be>
   8  *
   9  *      Changes:
  10  *      Apr 29 2003: physdev module support (bdschuym)
  11  *      Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
  12  *      Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
  13  *                   (bdschuym)
  14  *      Sep 01 2004: add IPv6 filtering (bdschuym)
  15  *
  16  *      This program is free software; you can redistribute it and/or
  17  *      modify it under the terms of the GNU General Public License
  18  *      as published by the Free Software Foundation; either version
  19  *      2 of the License, or (at your option) any later version.
  20  *
  21  *      Lennert dedicates this file to Kerstin Wurdinger.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/ip.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/if_ether.h>
  31 #include <linux/if_vlan.h>
  32 #include <linux/if_pppox.h>
  33 #include <linux/ppp_defs.h>
  34 #include <linux/netfilter_bridge.h>
  35 #include <linux/netfilter_ipv4.h>
  36 #include <linux/netfilter_ipv6.h>
  37 #include <linux/netfilter_arp.h>
  38 #include <linux/in_route.h>
  39 #include <linux/inetdevice.h>
  40
  41 #include <net/ip.h>
  42 #include <net/ipv6.h>
  43 #include <net/route.h>
  44
  45 #include <asm/uaccess.h>
  46 #include "br_private.h"
  47 #ifdef CONFIG_SYSCTL
  48 #include <linux/sysctl.h>
  49 #endif
  50
  51 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  52                                  (skb->nf_bridge->data))->daddr.ipv4)
  53 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  54 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  55
  56 #ifdef CONFIG_SYSCTL
  57 static struct ctl_table_header *brnf_sysctl_header;
  58 static int brnf_call_iptables __read_mostly = 1;
  59 static int brnf_call_ip6tables __read_mostly = 1;
  60 static int brnf_call_arptables __read_mostly = 1;
  61 static int brnf_filter_vlan_tagged __read_mostly = 0;
  62 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  63 #else
  64 #define brnf_filter_vlan_tagged 0
  65 #define brnf_filter_pppoe_tagged 0
  66 #endif
  67
  68 static inline __be16 vlan_proto(const struct sk_buff *skb)
  69 {
  70         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  71 }
  72
  73 #define IS_VLAN_IP(skb) \
  74         (skb->protocol == htons(ETH_P_8021Q) && \
  75          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  76          brnf_filter_vlan_tagged)
  77
  78 #define IS_VLAN_IPV6(skb) \
  79         (skb->protocol == htons(ETH_P_8021Q) && \
  80          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  81          brnf_filter_vlan_tagged)
  82
  83 #define IS_VLAN_ARP(skb) \
  84         (skb->protocol == htons(ETH_P_8021Q) && \
  85          vlan_proto(skb) == htons(ETH_P_ARP) && \
  86          brnf_filter_vlan_tagged)
  87
  88 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  89 {
  90         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  91                             sizeof(struct pppoe_hdr)));
  92 }
  93
  94 #define IS_PPPOE_IP(skb) \
  95         (skb->protocol == htons(ETH_P_PPP_SES) && \
  96          pppoe_proto(skb) == htons(PPP_IP) && \
  97          brnf_filter_pppoe_tagged)
  98
  99 #define IS_PPPOE_IPV6(skb) \
 100         (skb->protocol == htons(ETH_P_PPP_SES) && \
 101          pppoe_proto(skb) == htons(PPP_IPV6) && \
 102          brnf_filter_pppoe_tagged)
 103
 104 static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
 105 {
 106 }
 107
 108 static struct dst_ops fake_dst_ops = {
 109         .family =               AF_INET,
 110         .protocol =             cpu_to_be16(ETH_P_IP),
 111         .update_pmtu =          fake_update_pmtu,
 112         .entries =              ATOMIC_INIT(0),
 113 };
 114
 115 /*
 116  * Initialize bogus route table used to keep netfilter happy.
 117  * Currently, we fill in the PMTU entry because netfilter
 118  * refragmentation needs it, and the rt_flags entry because
 119  * ipt_REJECT needs it.  Future netfilter modules might
 120  * require us to fill additional fields.
 121  */
 122 void br_netfilter_rtable_init(struct net_bridge *br)
 123 {
 124         struct rtable *rt = &br->fake_rtable;
 125
 126         atomic_set(&rt->u.dst.__refcnt, 1);
 127         rt->u.dst.dev = br->dev;
 128         rt->u.dst.path = &rt->u.dst;
 129         rt->u.dst.metrics[RTAX_MTU - 1] = 1500;
 130         rt->u.dst.flags = DST_NOXFRM;
 131         rt->u.dst.ops = &fake_dst_ops;
 132 }
 133
 134 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 135 {
 136         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 137
 138         return port ? &port->br->fake_rtable : NULL;
 139 }
 140
 141 static inline struct net_device *bridge_parent(const struct net_device *dev)
 142 {
 143         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 144
 145         return port ? port->br->dev : NULL;
 146 }
 147
 148 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 149 {
 150         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 151         if (likely(skb->nf_bridge))
 152                 atomic_set(&(skb->nf_bridge->use), 1);
 153
 154         return skb->nf_bridge;
 155 }
 156
 157 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 158 {
 159         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 160
 161         if (atomic_read(&nf_bridge->use) > 1) {
 162                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 163
 164                 if (tmp) {
 165                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 166                         atomic_set(&tmp->use, 1);
 167                         nf_bridge_put(nf_bridge);
 168                 }
 169                 nf_bridge = tmp;
 170         }
 171         return nf_bridge;
 172 }
 173
 174 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 175 {
 176         unsigned int len = nf_bridge_encap_header_len(skb);
 177
 178         skb_push(skb, len);
 179         skb->network_header -= len;
 180 }
 181
 182 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 183 {
 184         unsigned int len = nf_bridge_encap_header_len(skb);
 185
 186         skb_pull(skb, len);
 187         skb->network_header += len;
 188 }
 189
 190 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 191 {
 192         unsigned int len = nf_bridge_encap_header_len(skb);
 193
 194         skb_pull_rcsum(skb, len);
 195         skb->network_header += len;
 196 }
 197
 198 static inline void nf_bridge_save_header(struct sk_buff *skb)
 199 {
 200         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 201
 202         skb_copy_from_linear_data_offset(skb, -header_size,
 203                                          skb->nf_bridge->data, header_size);
 204 }
 205
 206 /*
 207  * When forwarding bridge frames, we save a copy of the original
 208  * header before processing.
 209  */
 210 int nf_bridge_copy_header(struct sk_buff *skb)
 211 {
 212         int err;
 213         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 214
 215         err = skb_cow_head(skb, header_size);
 216         if (err)
 217                 return err;
 218
 219         skb_copy_to_linear_data_offset(skb, -header_size,
 220                                        skb->nf_bridge->data, header_size);
 221         __skb_push(skb, nf_bridge_encap_header_len(skb));
 222         return 0;
 223 }
 224
 225 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 226 /* Undo the changes made for ip6tables PREROUTING and continue the
 227  * bridge PRE_ROUTING hook. */
 228 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 229 {
 230         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 231         struct rtable *rt;
 232
 233         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 234                 skb->pkt_type = PACKET_OTHERHOST;
 235                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 236         }
 237         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 238
 239         rt = bridge_parent_rtable(nf_bridge->physindev);
 240         if (!rt) {
 241                 kfree_skb(skb);
 242                 return 0;
 243         }
 244         dst_hold(&rt->u.dst);
 245         skb->dst = &rt->u.dst;
 246
 247         skb->dev = nf_bridge->physindev;
 248         nf_bridge_push_encap_header(skb);
 249         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 250                        br_handle_frame_finish, 1);
 251
 252         return 0;
 253 }
 254
 255 static void __br_dnat_complain(void)
 256 {
 257         static unsigned long last_complaint;
 258
 259         if (jiffies - last_complaint >= 5 * HZ) {
 260                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 261                        "forwarding to be enabled\n");
 262                 last_complaint = jiffies;
 263         }
 264 }
 265
 266 /* This requires some explaining. If DNAT has taken place,
 267  * we will need to fix up the destination Ethernet address,
 268  * and this is a tricky process.
 269  *
 270  * There are two cases to consider:
 271  * 1. The packet was DNAT'ed to a device in the same bridge
 272  *    port group as it was received on. We can still bridge
 273  *    the packet.
 274  * 2. The packet was DNAT'ed to a different device, either
 275  *    a non-bridged device or another bridge port group.
 276  *    The packet will need to be routed.
 277  *
 278  * The correct way of distinguishing between these two cases is to
 279  * call ip_route_input() and to look at skb->dst->dev, which is
 280  * changed to the destination device if ip_route_input() succeeds.
 281  *
 282  * Let us first consider the case that ip_route_input() succeeds:
 283  *
 284  * If skb->dst->dev equals the logical bridge device the packet
 285  * came in on, we can consider this bridging. The packet is passed
 286  * through the neighbour output function to build a new destination
 287  * MAC address, which will make the packet enter br_nf_local_out()
 288  * not much later. In that function it is assured that the iptables
 289  * FORWARD chain is traversed for the packet.
 290  *
 291  * Otherwise, the packet is considered to be routed and we just
 292  * change the destination MAC address so that the packet will
 293  * later be passed up to the IP stack to be routed. For a redirected
 294  * packet, ip_route_input() will give back the localhost as output device,
 295  * which differs from the bridge device.
 296  *
 297  * Let us now consider the case that ip_route_input() fails:
 298  *
 299  * This can be because the destination address is martian, in which case
 300  * the packet will be dropped.
 301  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 302  * will fail, while __ip_route_output_key() will return success. The source
 303  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 304  * thinks we're handling a locally generated packet and won't care
 305  * if IP forwarding is allowed. We send a warning message to the users's
 306  * log telling her to put IP forwarding on.
 307  *
 308  * ip_route_input() will also fail if there is no route available.
 309  * In that case we just drop the packet.
 310  *
 311  * --Lennert, 20020411
 312  * --Bart, 20020416 (updated)
 313  * --Bart, 20021007 (updated)
 314  * --Bart, 20062711 (updated) */
 315 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 316 {
 317         if (skb->pkt_type == PACKET_OTHERHOST) {
 318                 skb->pkt_type = PACKET_HOST;
 319                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 320         }
 321         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 322
 323         skb->dev = bridge_parent(skb->dev);
 324         if (skb->dev) {
 325                 struct dst_entry *dst = skb->dst;
 326
 327                 nf_bridge_pull_encap_header(skb);
 328
 329                 if (dst->hh)
 330                         return neigh_hh_output(dst->hh, skb);
 331                 else if (dst->neighbour)
 332                         return dst->neighbour->output(skb);
 333         }
 334         kfree_skb(skb);
 335         return 0;
 336 }
 337
 338 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 339 {
 340         struct net_device *dev = skb->dev;
 341         struct iphdr *iph = ip_hdr(skb);
 342         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 343         struct rtable *rt;
 344         int err;
 345
 346         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 347                 skb->pkt_type = PACKET_OTHERHOST;
 348                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 349         }
 350         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 351         if (dnat_took_place(skb)) {
 352                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 353                         struct flowi fl = {
 354                                 .nl_u = {
 355                                         .ip4_u = {
 356                                                  .daddr = iph->daddr,
 357                                                  .saddr = 0,
 358                                                  .tos = RT_TOS(iph->tos) },
 359                                 },
 360                                 .proto = 0,
 361                         };
 362                         struct in_device *in_dev = in_dev_get(dev);
 363
 364                         /* If err equals -EHOSTUNREACH the error is due to a
 365                          * martian destination or due to the fact that
 366                          * forwarding is disabled. For most martian packets,
 367                          * ip_route_output_key() will fail. It won't fail for 2 types of
 368                          * martian destinations: loopback destinations and destination
 369                          * 0.0.0.0. In both cases the packet will be dropped because the
 370                          * destination is the loopback device and not the bridge. */
 371                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 372                                 goto free_skb;
 373
 374                         if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 375                                 /* - Bridged-and-DNAT'ed traffic doesn't
 376                                  *   require ip_forwarding. */
 377                                 if (((struct dst_entry *)rt)->dev == dev) {
 378                                         skb->dst = (struct dst_entry *)rt;
 379                                         goto bridged_dnat;
 380                                 }
 381                                 /* we are sure that forwarding is disabled, so printing
 382                                  * this message is no problem. Note that the packet could
 383                                  * still have a martian destination address, in which case
 384                                  * the packet could be dropped even if forwarding were enabled */
 385                                 __br_dnat_complain();
 386                                 dst_release((struct dst_entry *)rt);
 387                         }
 388 free_skb:
 389                         kfree_skb(skb);
 390                         return 0;
 391                 } else {
 392                         if (skb->dst->dev == dev) {
 393 bridged_dnat:
 394                                 /* Tell br_nf_local_out this is a
 395                                  * bridged frame */
 396                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 397                                 skb->dev = nf_bridge->physindev;
 398                                 nf_bridge_push_encap_header(skb);
 399                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 400                                                skb, skb->dev, NULL,
 401                                                br_nf_pre_routing_finish_bridge,
 402                                                1);
 403                                 return 0;
 404                         }
 405                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 406                         skb->pkt_type = PACKET_HOST;
 407                 }
 408         } else {
 409                 rt = bridge_parent_rtable(nf_bridge->physindev);
 410                 if (!rt) {
 411                         kfree_skb(skb);
 412                         return 0;
 413                 }
 414                 dst_hold(&rt->u.dst);
 415                 skb->dst = &rt->u.dst;
 416         }
 417
 418         skb->dev = nf_bridge->physindev;
 419         nf_bridge_push_encap_header(skb);
 420         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 421                        br_handle_frame_finish, 1);
 422
 423         return 0;
 424 }
 425
 426 /* Some common code for IPv4/IPv6 */
 427 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 428 {
 429         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 430
 431         if (skb->pkt_type == PACKET_OTHERHOST) {
 432                 skb->pkt_type = PACKET_HOST;
 433                 nf_bridge->mask |= BRNF_PKT_TYPE;
 434         }
 435
 436         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 437         nf_bridge->physindev = skb->dev;
 438         skb->dev = bridge_parent(skb->dev);
 439
 440         return skb->dev;
 441 }
 442
 443 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 444 static int check_hbh_len(struct sk_buff *skb)
 445 {
 446         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 447         u32 pkt_len;
 448         const unsigned char *nh = skb_network_header(skb);
 449         int off = raw - nh;
 450         int len = (raw[1] + 1) << 3;
 451
 452         if ((raw + len) - skb->data > skb_headlen(skb))
 453                 goto bad;
 454
 455         off += 2;
 456         len -= 2;
 457
 458         while (len > 0) {
 459                 int optlen = nh[off + 1] + 2;
 460
 461                 switch (nh[off]) {
 462                 case IPV6_TLV_PAD0:
 463                         optlen = 1;
 464                         break;
 465
 466                 case IPV6_TLV_PADN:
 467                         break;
 468
 469                 case IPV6_TLV_JUMBO:
 470                         if (nh[off + 1] != 4 || (off & 3) != 2)
 471                                 goto bad;
 472                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 473                         if (pkt_len <= IPV6_MAXPLEN ||
 474                             ipv6_hdr(skb)->payload_len)
 475                                 goto bad;
 476                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 477                                 goto bad;
 478                         if (pskb_trim_rcsum(skb,
 479                                             pkt_len + sizeof(struct ipv6hdr)))
 480                                 goto bad;
 481                         nh = skb_network_header(skb);
 482                         break;
 483                 default:
 484                         if (optlen > len)
 485                                 goto bad;
 486                         break;
 487                 }
 488                 off += optlen;
 489                 len -= optlen;
 490         }
 491         if (len == 0)
 492                 return 0;
 493 bad:
 494         return -1;
 495
 496 }
 497
 498 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 499  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 500 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 501                                            struct sk_buff *skb,
 502                                            const struct net_device *in,
 503                                            const struct net_device *out,
 504                                            int (*okfn)(struct sk_buff *))
 505 {
 506         struct ipv6hdr *hdr;
 507         u32 pkt_len;
 508
 509         if (skb->len < sizeof(struct ipv6hdr))
 510                 goto inhdr_error;
 511
 512         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 513                 goto inhdr_error;
 514
 515         hdr = ipv6_hdr(skb);
 516
 517         if (hdr->version != 6)
 518                 goto inhdr_error;
 519
 520         pkt_len = ntohs(hdr->payload_len);
 521
 522         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 523                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 524                         goto inhdr_error;
 525                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 526                         goto inhdr_error;
 527         }
 528         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 529                 goto inhdr_error;
 530
 531         nf_bridge_put(skb->nf_bridge);
 532         if (!nf_bridge_alloc(skb))
 533                 return NF_DROP;
 534         if (!setup_pre_routing(skb))
 535                 return NF_DROP;
 536
 537         NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 538                 br_nf_pre_routing_finish_ipv6);
 539
 540         return NF_STOLEN;
 541
 542 inhdr_error:
 543         return NF_DROP;
 544 }
 545
 546 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 547  * Replicate the checks that IPv4 does on packet reception.
 548  * Set skb->dev to the bridge device (i.e. parent of the
 549  * receiving device) to make netfilter happy, the REDIRECT
 550  * target in particular.  Save the original destination IP
 551  * address to be able to detect DNAT afterwards. */
 552 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 553                                       const struct net_device *in,
 554                                       const struct net_device *out,
 555                                       int (*okfn)(struct sk_buff *))
 556 {
 557         struct iphdr *iph;
 558         __u32 len = nf_bridge_encap_header_len(skb);
 559
 560         if (unlikely(!pskb_may_pull(skb, len)))
 561                 goto out;
 562
 563         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 564             IS_PPPOE_IPV6(skb)) {
 565 #ifdef CONFIG_SYSCTL
 566                 if (!brnf_call_ip6tables)
 567                         return NF_ACCEPT;
 568 #endif
 569                 nf_bridge_pull_encap_header_rcsum(skb);
 570                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 571         }
 572 #ifdef CONFIG_SYSCTL
 573         if (!brnf_call_iptables)
 574                 return NF_ACCEPT;
 575 #endif
 576
 577         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 578             !IS_PPPOE_IP(skb))
 579                 return NF_ACCEPT;
 580
 581         nf_bridge_pull_encap_header_rcsum(skb);
 582
 583         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 584                 goto inhdr_error;
 585
 586         iph = ip_hdr(skb);
 587         if (iph->ihl < 5 || iph->version != 4)
 588                 goto inhdr_error;
 589
 590         if (!pskb_may_pull(skb, 4 * iph->ihl))
 591                 goto inhdr_error;
 592
 593         iph = ip_hdr(skb);
 594         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 595                 goto inhdr_error;
 596
 597         len = ntohs(iph->tot_len);
 598         if (skb->len < len || len < 4 * iph->ihl)
 599                 goto inhdr_error;
 600
 601         pskb_trim_rcsum(skb, len);
 602
 603         nf_bridge_put(skb->nf_bridge);
 604         if (!nf_bridge_alloc(skb))
 605                 return NF_DROP;
 606         if (!setup_pre_routing(skb))
 607                 return NF_DROP;
 608         store_orig_dstaddr(skb);
 609
 610         NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 611                 br_nf_pre_routing_finish);
 612
 613         return NF_STOLEN;
 614
 615 inhdr_error:
 616 //      IP_INC_STATS_BH(IpInHdrErrors);
 617 out:
 618         return NF_DROP;
 619 }
 620
 621
 622 /* PF_BRIDGE/LOCAL_IN ************************************************/
 623 /* The packet is locally destined, which requires a real
 624  * dst_entry, so detach the fake one.  On the way up, the
 625  * packet would pass through PRE_ROUTING again (which already
 626  * took place when the packet entered the bridge), but we
 627  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 628  * prevent this from happening. */
 629 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 630                                    const struct net_device *in,
 631                                    const struct net_device *out,
 632                                    int (*okfn)(struct sk_buff *))
 633 {
 634         struct rtable *rt = skb_rtable(skb);
 635
 636         if (rt && rt == bridge_parent_rtable(in)) {
 637                 dst_release(&rt->u.dst);
 638                 skb->dst = NULL;
 639         }
 640
 641         return NF_ACCEPT;
 642 }
 643
 644 /* PF_BRIDGE/FORWARD *************************************************/
 645 static int br_nf_forward_finish(struct sk_buff *skb)
 646 {
 647         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 648         struct net_device *in;
 649
 650         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 651                 in = nf_bridge->physindev;
 652                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 653                         skb->pkt_type = PACKET_OTHERHOST;
 654                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 655                 }
 656         } else {
 657                 in = *((struct net_device **)(skb->cb));
 658         }
 659         nf_bridge_push_encap_header(skb);
 660         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 661                        skb->dev, br_forward_finish, 1);
 662         return 0;
 663 }
 664
 665 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 666  * netfilter with indev and outdev set to the bridge device,
 667  * but we are still able to filter on the 'real' indev/outdev
 668  * because of the physdev module. For ARP, indev and outdev are the
 669  * bridge ports. */
 670 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 671                                      const struct net_device *in,
 672                                      const struct net_device *out,
 673                                      int (*okfn)(struct sk_buff *))
 674 {
 675         struct nf_bridge_info *nf_bridge;
 676         struct net_device *parent;
 677         u_int8_t pf;
 678
 679         if (!skb->nf_bridge)
 680                 return NF_ACCEPT;
 681
 682         /* Need exclusive nf_bridge_info since we might have multiple
 683          * different physoutdevs. */
 684         if (!nf_bridge_unshare(skb))
 685                 return NF_DROP;
 686
 687         parent = bridge_parent(out);
 688         if (!parent)
 689                 return NF_DROP;
 690
 691         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 692             IS_PPPOE_IP(skb))
 693                 pf = PF_INET;
 694         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 695                  IS_PPPOE_IPV6(skb))
 696                 pf = PF_INET6;
 697         else
 698                 return NF_ACCEPT;
 699
 700         nf_bridge_pull_encap_header(skb);
 701
 702         nf_bridge = skb->nf_bridge;
 703         if (skb->pkt_type == PACKET_OTHERHOST) {
 704                 skb->pkt_type = PACKET_HOST;
 705                 nf_bridge->mask |= BRNF_PKT_TYPE;
 706         }
 707
 708         /* The physdev module checks on this */
 709         nf_bridge->mask |= BRNF_BRIDGED;
 710         nf_bridge->physoutdev = skb->dev;
 711
 712         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 713                 br_nf_forward_finish);
 714
 715         return NF_STOLEN;
 716 }
 717
 718 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 719                                       const struct net_device *in,
 720                                       const struct net_device *out,
 721                                       int (*okfn)(struct sk_buff *))
 722 {
 723         struct net_device **d = (struct net_device **)(skb->cb);
 724
 725 #ifdef CONFIG_SYSCTL
 726         if (!brnf_call_arptables)
 727                 return NF_ACCEPT;
 728 #endif
 729
 730         if (skb->protocol != htons(ETH_P_ARP)) {
 731                 if (!IS_VLAN_ARP(skb))
 732                         return NF_ACCEPT;
 733                 nf_bridge_pull_encap_header(skb);
 734         }
 735
 736         if (arp_hdr(skb)->ar_pln != 4) {
 737                 if (IS_VLAN_ARP(skb))
 738                         nf_bridge_push_encap_header(skb);
 739                 return NF_ACCEPT;
 740         }
 741         *d = (struct net_device *)in;
 742         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 743                 (struct net_device *)out, br_nf_forward_finish);
 744
 745         return NF_STOLEN;
 746 }
 747
 748 /* PF_BRIDGE/LOCAL_OUT ***********************************************
 749  *
 750  * This function sees both locally originated IP packets and forwarded
 751  * IP packets (in both cases the destination device is a bridge
 752  * device). It also sees bridged-and-DNAT'ed packets.
 753  *
 754  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 755  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 756  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 757  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 758  * will be executed.
 759  */
 760 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 761                                     const struct net_device *in,
 762                                     const struct net_device *out,
 763                                     int (*okfn)(struct sk_buff *))
 764 {
 765         struct net_device *realindev;
 766         struct nf_bridge_info *nf_bridge;
 767
 768         if (!skb->nf_bridge)
 769                 return NF_ACCEPT;
 770
 771         /* Need exclusive nf_bridge_info since we might have multiple
 772          * different physoutdevs. */
 773         if (!nf_bridge_unshare(skb))
 774                 return NF_DROP;
 775
 776         nf_bridge = skb->nf_bridge;
 777         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
 778                 return NF_ACCEPT;
 779
 780         /* Bridged, take PF_BRIDGE/FORWARD.
 781          * (see big note in front of br_nf_pre_routing_finish) */
 782         nf_bridge->physoutdev = skb->dev;
 783         realindev = nf_bridge->physindev;
 784
 785         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 786                 skb->pkt_type = PACKET_OTHERHOST;
 787                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 788         }
 789         nf_bridge_push_encap_header(skb);
 790
 791         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
 792                 br_forward_finish);
 793         return NF_STOLEN;
 794 }
 795
 796 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 797 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 798 {
 799         if (skb->nfct != NULL &&
 800             (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 801             skb->len > skb->dev->mtu &&
 802             !skb_is_gso(skb))
 803                 return ip_fragment(skb, br_dev_queue_push_xmit);
 804         else
 805                 return br_dev_queue_push_xmit(skb);
 806 }
 807 #else
 808 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 809 {
 810         return br_dev_queue_push_xmit(skb);
 811 }
 812 #endif
 813
 814 /* PF_BRIDGE/POST_ROUTING ********************************************/
 815 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 816                                        const struct net_device *in,
 817                                        const struct net_device *out,
 818                                        int (*okfn)(struct sk_buff *))
 819 {
 820         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 821         struct net_device *realoutdev = bridge_parent(skb->dev);
 822         u_int8_t pf;
 823
 824 #ifdef CONFIG_NETFILTER_DEBUG
 825         /* Be very paranoid. This probably won't happen anymore, but let's
 826          * keep the check just to be sure... */
 827         if (skb_mac_header(skb) < skb->head ||
 828             skb_mac_header(skb) + ETH_HLEN > skb->data) {
 829                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 830                        "bad mac.raw pointer.\n");
 831                 goto print_error;
 832         }
 833 #endif
 834
 835         if (!nf_bridge)
 836                 return NF_ACCEPT;
 837
 838         if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
 839                 return NF_ACCEPT;
 840
 841         if (!realoutdev)
 842                 return NF_DROP;
 843
 844         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 845             IS_PPPOE_IP(skb))
 846                 pf = PF_INET;
 847         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 848                  IS_PPPOE_IPV6(skb))
 849                 pf = PF_INET6;
 850         else
 851                 return NF_ACCEPT;
 852
 853 #ifdef CONFIG_NETFILTER_DEBUG
 854         if (skb->dst == NULL) {
 855                 printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
 856                 goto print_error;
 857         }
 858 #endif
 859
 860         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 861          * about the value of skb->pkt_type. */
 862         if (skb->pkt_type == PACKET_OTHERHOST) {
 863                 skb->pkt_type = PACKET_HOST;
 864                 nf_bridge->mask |= BRNF_PKT_TYPE;
 865         }
 866
 867         nf_bridge_pull_encap_header(skb);
 868         nf_bridge_save_header(skb);
 869
 870         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 871                 br_nf_dev_queue_xmit);
 872
 873         return NF_STOLEN;
 874
 875 #ifdef CONFIG_NETFILTER_DEBUG
 876 print_error:
 877         if (skb->dev != NULL) {
 878                 printk("[%s]", skb->dev->name);
 879                 if (realoutdev)
 880                         printk("[%s]", realoutdev->name);
 881         }
 882         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb),
 883                skb->data);
 884         dump_stack();
 885         return NF_ACCEPT;
 886 #endif
 887 }
 888
 889 /* IP/SABOTAGE *****************************************************/
 890 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 891  * for the second time. */
 892 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 893                                    const struct net_device *in,
 894                                    const struct net_device *out,
 895                                    int (*okfn)(struct sk_buff *))
 896 {
 897         if (skb->nf_bridge &&
 898             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 899                 return NF_STOP;
 900         }
 901
 902         return NF_ACCEPT;
 903 }
 904
 905 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 906  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 907  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 908  * ip_refrag() can return NF_STOLEN. */
 909 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 910         { .hook = br_nf_pre_routing,
 911           .owner = THIS_MODULE,
 912           .pf = PF_BRIDGE,
 913           .hooknum = NF_BR_PRE_ROUTING,
 914           .priority = NF_BR_PRI_BRNF, },
 915         { .hook = br_nf_local_in,
 916           .owner = THIS_MODULE,
 917           .pf = PF_BRIDGE,
 918           .hooknum = NF_BR_LOCAL_IN,
 919           .priority = NF_BR_PRI_BRNF, },
 920         { .hook = br_nf_forward_ip,
 921           .owner = THIS_MODULE,
 922           .pf = PF_BRIDGE,
 923           .hooknum = NF_BR_FORWARD,
 924           .priority = NF_BR_PRI_BRNF - 1, },
 925         { .hook = br_nf_forward_arp,
 926           .owner = THIS_MODULE,
 927           .pf = PF_BRIDGE,
 928           .hooknum = NF_BR_FORWARD,
 929           .priority = NF_BR_PRI_BRNF, },
 930         { .hook = br_nf_local_out,
 931           .owner = THIS_MODULE,
 932           .pf = PF_BRIDGE,
 933           .hooknum = NF_BR_LOCAL_OUT,
 934           .priority = NF_BR_PRI_FIRST, },
 935         { .hook = br_nf_post_routing,
 936           .owner = THIS_MODULE,
 937           .pf = PF_BRIDGE,
 938           .hooknum = NF_BR_POST_ROUTING,
 939           .priority = NF_BR_PRI_LAST, },
 940         { .hook = ip_sabotage_in,
 941           .owner = THIS_MODULE,
 942           .pf = PF_INET,
 943           .hooknum = NF_INET_PRE_ROUTING,
 944           .priority = NF_IP_PRI_FIRST, },
 945         { .hook = ip_sabotage_in,
 946           .owner = THIS_MODULE,
 947           .pf = PF_INET6,
 948           .hooknum = NF_INET_PRE_ROUTING,
 949           .priority = NF_IP6_PRI_FIRST, },
 950 };
 951
 952 #ifdef CONFIG_SYSCTL
 953 static
 954 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
 955                             void __user * buffer, size_t * lenp, loff_t * ppos)
 956 {
 957         int ret;
 958
 959         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 960
 961         if (write && *(int *)(ctl->data))
 962                 *(int *)(ctl->data) = 1;
 963         return ret;
 964 }
 965
 966 static ctl_table brnf_table[] = {
 967         {
 968                 .procname       = "bridge-nf-call-arptables",
 969                 .data           = &brnf_call_arptables,
 970                 .maxlen         = sizeof(int),
 971                 .mode           = 0644,
 972                 .proc_handler   = brnf_sysctl_call_tables,
 973         },
 974         {
 975                 .procname       = "bridge-nf-call-iptables",
 976                 .data           = &brnf_call_iptables,
 977                 .maxlen         = sizeof(int),
 978                 .mode           = 0644,
 979                 .proc_handler   = brnf_sysctl_call_tables,
 980         },
 981         {
 982                 .procname       = "bridge-nf-call-ip6tables",
 983                 .data           = &brnf_call_ip6tables,
 984                 .maxlen         = sizeof(int),
 985                 .mode           = 0644,
 986                 .proc_handler   = brnf_sysctl_call_tables,
 987         },
 988         {
 989                 .procname       = "bridge-nf-filter-vlan-tagged",
 990                 .data           = &brnf_filter_vlan_tagged,
 991                 .maxlen         = sizeof(int),
 992                 .mode           = 0644,
 993                 .proc_handler   = brnf_sysctl_call_tables,
 994         },
 995         {
 996                 .procname       = "bridge-nf-filter-pppoe-tagged",
 997                 .data           = &brnf_filter_pppoe_tagged,
 998                 .maxlen         = sizeof(int),
 999                 .mode           = 0644,
1000                 .proc_handler   = brnf_sysctl_call_tables,
1001         },
1002         { .ctl_name = 0 }
1003 };
1004
1005 static struct ctl_path brnf_path[] = {
1006         { .procname = "net", .ctl_name = CTL_NET, },
1007         { .procname = "bridge", .ctl_name = NET_BRIDGE, },
1008         { }
1009 };
1010 #endif
1011
1012 int __init br_netfilter_init(void)
1013 {
1014         int ret;
1015
1016         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1017         if (ret < 0)
1018                 return ret;
1019 #ifdef CONFIG_SYSCTL
1020         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1021         if (brnf_sysctl_header == NULL) {
1022                 printk(KERN_WARNING
1023                        "br_netfilter: can't register to sysctl.\n");
1024                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1025                 return -ENOMEM;
1026         }
1027 #endif
1028         printk(KERN_NOTICE "Bridge firewalling registered\n");
1029         return 0;
1030 }
1031
1032 void br_netfilter_fini(void)
1033 {
1034         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1035 #ifdef CONFIG_SYSCTL
1036         unregister_sysctl_table(brnf_sysctl_header);
1037 #endif
1038 }