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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
 232         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 233                 skb->pkt_type = PACKET_OTHERHOST;
 234                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 235         }
 236         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 237
 238         skb->rtable = bridge_parent_rtable(nf_bridge->physindev);
 239         if (!skb->rtable) {
 240                 kfree_skb(skb);
 241                 return 0;
 242         }
 243         dst_hold(&skb->rtable->u.dst);
 244
 245         skb->dev = nf_bridge->physindev;
 246         nf_bridge_push_encap_header(skb);
 247         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 248                        br_handle_frame_finish, 1);
 249
 250         return 0;
 251 }
 252
 253 static void __br_dnat_complain(void)
 254 {
 255         static unsigned long last_complaint;
 256
 257         if (jiffies - last_complaint >= 5 * HZ) {
 258                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 259                        "forwarding to be enabled\n");
 260                 last_complaint = jiffies;
 261         }
 262 }
 263
 264 /* This requires some explaining. If DNAT has taken place,
 265  * we will need to fix up the destination Ethernet address,
 266  * and this is a tricky process.
 267  *
 268  * There are two cases to consider:
 269  * 1. The packet was DNAT'ed to a device in the same bridge
 270  *    port group as it was received on. We can still bridge
 271  *    the packet.
 272  * 2. The packet was DNAT'ed to a different device, either
 273  *    a non-bridged device or another bridge port group.
 274  *    The packet will need to be routed.
 275  *
 276  * The correct way of distinguishing between these two cases is to
 277  * call ip_route_input() and to look at skb->dst->dev, which is
 278  * changed to the destination device if ip_route_input() succeeds.
 279  *
 280  * Let us first consider the case that ip_route_input() succeeds:
 281  *
 282  * If skb->dst->dev equals the logical bridge device the packet
 283  * came in on, we can consider this bridging. The packet is passed
 284  * through the neighbour output function to build a new destination
 285  * MAC address, which will make the packet enter br_nf_local_out()
 286  * not much later. In that function it is assured that the iptables
 287  * FORWARD chain is traversed for the packet.
 288  *
 289  * Otherwise, the packet is considered to be routed and we just
 290  * change the destination MAC address so that the packet will
 291  * later be passed up to the IP stack to be routed. For a redirected
 292  * packet, ip_route_input() will give back the localhost as output device,
 293  * which differs from the bridge device.
 294  *
 295  * Let us now consider the case that ip_route_input() fails:
 296  *
 297  * This can be because the destination address is martian, in which case
 298  * the packet will be dropped.
 299  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 300  * will fail, while __ip_route_output_key() will return success. The source
 301  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 302  * thinks we're handling a locally generated packet and won't care
 303  * if IP forwarding is allowed. We send a warning message to the users's
 304  * log telling her to put IP forwarding on.
 305  *
 306  * ip_route_input() will also fail if there is no route available.
 307  * In that case we just drop the packet.
 308  *
 309  * --Lennert, 20020411
 310  * --Bart, 20020416 (updated)
 311  * --Bart, 20021007 (updated)
 312  * --Bart, 20062711 (updated) */
 313 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 314 {
 315         if (skb->pkt_type == PACKET_OTHERHOST) {
 316                 skb->pkt_type = PACKET_HOST;
 317                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 318         }
 319         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 320
 321         skb->dev = bridge_parent(skb->dev);
 322         if (skb->dev) {
 323                 struct dst_entry *dst = skb->dst;
 324
 325                 nf_bridge_pull_encap_header(skb);
 326
 327                 if (dst->hh)
 328                         return neigh_hh_output(dst->hh, skb);
 329                 else if (dst->neighbour)
 330                         return dst->neighbour->output(skb);
 331         }
 332         kfree_skb(skb);
 333         return 0;
 334 }
 335
 336 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 337 {
 338         struct net_device *dev = skb->dev;
 339         struct iphdr *iph = ip_hdr(skb);
 340         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 341         int err;
 342
 343         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 344                 skb->pkt_type = PACKET_OTHERHOST;
 345                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 346         }
 347         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 348         if (dnat_took_place(skb)) {
 349                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 350                         struct rtable *rt;
 351                         struct flowi fl = {
 352                                 .nl_u = {
 353                                         .ip4_u = {
 354                                                  .daddr = iph->daddr,
 355                                                  .saddr = 0,
 356                                                  .tos = RT_TOS(iph->tos) },
 357                                 },
 358                                 .proto = 0,
 359                         };
 360                         struct in_device *in_dev = in_dev_get(dev);
 361
 362                         /* If err equals -EHOSTUNREACH the error is due to a
 363                          * martian destination or due to the fact that
 364                          * forwarding is disabled. For most martian packets,
 365                          * ip_route_output_key() will fail. It won't fail for 2 types of
 366                          * martian destinations: loopback destinations and destination
 367                          * 0.0.0.0. In both cases the packet will be dropped because the
 368                          * destination is the loopback device and not the bridge. */
 369                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 370                                 goto free_skb;
 371
 372                         if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 373                                 /* - Bridged-and-DNAT'ed traffic doesn't
 374                                  *   require ip_forwarding. */
 375                                 if (((struct dst_entry *)rt)->dev == dev) {
 376                                         skb->dst = (struct dst_entry *)rt;
 377                                         goto bridged_dnat;
 378                                 }
 379                                 /* we are sure that forwarding is disabled, so printing
 380                                  * this message is no problem. Note that the packet could
 381                                  * still have a martian destination address, in which case
 382                                  * the packet could be dropped even if forwarding were enabled */
 383                                 __br_dnat_complain();
 384                                 dst_release((struct dst_entry *)rt);
 385                         }
 386 free_skb:
 387                         kfree_skb(skb);
 388                         return 0;
 389                 } else {
 390                         if (skb->dst->dev == dev) {
 391 bridged_dnat:
 392                                 /* Tell br_nf_local_out this is a
 393                                  * bridged frame */
 394                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 395                                 skb->dev = nf_bridge->physindev;
 396                                 nf_bridge_push_encap_header(skb);
 397                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 398                                                skb, skb->dev, NULL,
 399                                                br_nf_pre_routing_finish_bridge,
 400                                                1);
 401                                 return 0;
 402                         }
 403                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 404                         skb->pkt_type = PACKET_HOST;
 405                 }
 406         } else {
 407                 skb->rtable = bridge_parent_rtable(nf_bridge->physindev);
 408                 if (!skb->rtable) {
 409                         kfree_skb(skb);
 410                         return 0;
 411                 }
 412                 dst_hold(&skb->rtable->u.dst);
 413         }
 414
 415         skb->dev = nf_bridge->physindev;
 416         nf_bridge_push_encap_header(skb);
 417         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 418                        br_handle_frame_finish, 1);
 419
 420         return 0;
 421 }
 422
 423 /* Some common code for IPv4/IPv6 */
 424 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 425 {
 426         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 427
 428         if (skb->pkt_type == PACKET_OTHERHOST) {
 429                 skb->pkt_type = PACKET_HOST;
 430                 nf_bridge->mask |= BRNF_PKT_TYPE;
 431         }
 432
 433         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 434         nf_bridge->physindev = skb->dev;
 435         skb->dev = bridge_parent(skb->dev);
 436
 437         return skb->dev;
 438 }
 439
 440 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 441 static int check_hbh_len(struct sk_buff *skb)
 442 {
 443         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 444         u32 pkt_len;
 445         const unsigned char *nh = skb_network_header(skb);
 446         int off = raw - nh;
 447         int len = (raw[1] + 1) << 3;
 448
 449         if ((raw + len) - skb->data > skb_headlen(skb))
 450                 goto bad;
 451
 452         off += 2;
 453         len -= 2;
 454
 455         while (len > 0) {
 456                 int optlen = nh[off + 1] + 2;
 457
 458                 switch (nh[off]) {
 459                 case IPV6_TLV_PAD0:
 460                         optlen = 1;
 461                         break;
 462
 463                 case IPV6_TLV_PADN:
 464                         break;
 465
 466                 case IPV6_TLV_JUMBO:
 467                         if (nh[off + 1] != 4 || (off & 3) != 2)
 468                                 goto bad;
 469                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 470                         if (pkt_len <= IPV6_MAXPLEN ||
 471                             ipv6_hdr(skb)->payload_len)
 472                                 goto bad;
 473                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 474                                 goto bad;
 475                         if (pskb_trim_rcsum(skb,
 476                                             pkt_len + sizeof(struct ipv6hdr)))
 477                                 goto bad;
 478                         nh = skb_network_header(skb);
 479                         break;
 480                 default:
 481                         if (optlen > len)
 482                                 goto bad;
 483                         break;
 484                 }
 485                 off += optlen;
 486                 len -= optlen;
 487         }
 488         if (len == 0)
 489                 return 0;
 490 bad:
 491         return -1;
 492
 493 }
 494
 495 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 496  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 497 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 498                                            struct sk_buff *skb,
 499                                            const struct net_device *in,
 500                                            const struct net_device *out,
 501                                            int (*okfn)(struct sk_buff *))
 502 {
 503         struct ipv6hdr *hdr;
 504         u32 pkt_len;
 505
 506         if (skb->len < sizeof(struct ipv6hdr))
 507                 goto inhdr_error;
 508
 509         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 510                 goto inhdr_error;
 511
 512         hdr = ipv6_hdr(skb);
 513
 514         if (hdr->version != 6)
 515                 goto inhdr_error;
 516
 517         pkt_len = ntohs(hdr->payload_len);
 518
 519         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 520                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 521                         goto inhdr_error;
 522                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 523                         goto inhdr_error;
 524         }
 525         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 526                 goto inhdr_error;
 527
 528         nf_bridge_put(skb->nf_bridge);
 529         if (!nf_bridge_alloc(skb))
 530                 return NF_DROP;
 531         if (!setup_pre_routing(skb))
 532                 return NF_DROP;
 533
 534         NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 535                 br_nf_pre_routing_finish_ipv6);
 536
 537         return NF_STOLEN;
 538
 539 inhdr_error:
 540         return NF_DROP;
 541 }
 542
 543 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 544  * Replicate the checks that IPv4 does on packet reception.
 545  * Set skb->dev to the bridge device (i.e. parent of the
 546  * receiving device) to make netfilter happy, the REDIRECT
 547  * target in particular.  Save the original destination IP
 548  * address to be able to detect DNAT afterwards. */
 549 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 550                                       const struct net_device *in,
 551                                       const struct net_device *out,
 552                                       int (*okfn)(struct sk_buff *))
 553 {
 554         struct iphdr *iph;
 555         __u32 len = nf_bridge_encap_header_len(skb);
 556
 557         if (unlikely(!pskb_may_pull(skb, len)))
 558                 goto out;
 559
 560         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 561             IS_PPPOE_IPV6(skb)) {
 562 #ifdef CONFIG_SYSCTL
 563                 if (!brnf_call_ip6tables)
 564                         return NF_ACCEPT;
 565 #endif
 566                 nf_bridge_pull_encap_header_rcsum(skb);
 567                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 568         }
 569 #ifdef CONFIG_SYSCTL
 570         if (!brnf_call_iptables)
 571                 return NF_ACCEPT;
 572 #endif
 573
 574         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 575             !IS_PPPOE_IP(skb))
 576                 return NF_ACCEPT;
 577
 578         nf_bridge_pull_encap_header_rcsum(skb);
 579
 580         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 581                 goto inhdr_error;
 582
 583         iph = ip_hdr(skb);
 584         if (iph->ihl < 5 || iph->version != 4)
 585                 goto inhdr_error;
 586
 587         if (!pskb_may_pull(skb, 4 * iph->ihl))
 588                 goto inhdr_error;
 589
 590         iph = ip_hdr(skb);
 591         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 592                 goto inhdr_error;
 593
 594         len = ntohs(iph->tot_len);
 595         if (skb->len < len || len < 4 * iph->ihl)
 596                 goto inhdr_error;
 597
 598         pskb_trim_rcsum(skb, len);
 599
 600         nf_bridge_put(skb->nf_bridge);
 601         if (!nf_bridge_alloc(skb))
 602                 return NF_DROP;
 603         if (!setup_pre_routing(skb))
 604                 return NF_DROP;
 605         store_orig_dstaddr(skb);
 606
 607         NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 608                 br_nf_pre_routing_finish);
 609
 610         return NF_STOLEN;
 611
 612 inhdr_error:
 613 //      IP_INC_STATS_BH(IpInHdrErrors);
 614 out:
 615         return NF_DROP;
 616 }
 617
 618
 619 /* PF_BRIDGE/LOCAL_IN ************************************************/
 620 /* The packet is locally destined, which requires a real
 621  * dst_entry, so detach the fake one.  On the way up, the
 622  * packet would pass through PRE_ROUTING again (which already
 623  * took place when the packet entered the bridge), but we
 624  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 625  * prevent this from happening. */
 626 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 627                                    const struct net_device *in,
 628                                    const struct net_device *out,
 629                                    int (*okfn)(struct sk_buff *))
 630 {
 631         if (skb->rtable && skb->rtable == bridge_parent_rtable(in)) {
 632                 dst_release(&skb->rtable->u.dst);
 633                 skb->rtable = NULL;
 634         }
 635
 636         return NF_ACCEPT;
 637 }
 638
 639 /* PF_BRIDGE/FORWARD *************************************************/
 640 static int br_nf_forward_finish(struct sk_buff *skb)
 641 {
 642         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 643         struct net_device *in;
 644
 645         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 646                 in = nf_bridge->physindev;
 647                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 648                         skb->pkt_type = PACKET_OTHERHOST;
 649                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 650                 }
 651         } else {
 652                 in = *((struct net_device **)(skb->cb));
 653         }
 654         nf_bridge_push_encap_header(skb);
 655         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 656                        skb->dev, br_forward_finish, 1);
 657         return 0;
 658 }
 659
 660 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 661  * netfilter with indev and outdev set to the bridge device,
 662  * but we are still able to filter on the 'real' indev/outdev
 663  * because of the physdev module. For ARP, indev and outdev are the
 664  * bridge ports. */
 665 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 666                                      const struct net_device *in,
 667                                      const struct net_device *out,
 668                                      int (*okfn)(struct sk_buff *))
 669 {
 670         struct nf_bridge_info *nf_bridge;
 671         struct net_device *parent;
 672         u_int8_t pf;
 673
 674         if (!skb->nf_bridge)
 675                 return NF_ACCEPT;
 676
 677         /* Need exclusive nf_bridge_info since we might have multiple
 678          * different physoutdevs. */
 679         if (!nf_bridge_unshare(skb))
 680                 return NF_DROP;
 681
 682         parent = bridge_parent(out);
 683         if (!parent)
 684                 return NF_DROP;
 685
 686         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 687             IS_PPPOE_IP(skb))
 688                 pf = PF_INET;
 689         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 690                  IS_PPPOE_IPV6(skb))
 691                 pf = PF_INET6;
 692         else
 693                 return NF_ACCEPT;
 694
 695         nf_bridge_pull_encap_header(skb);
 696
 697         nf_bridge = skb->nf_bridge;
 698         if (skb->pkt_type == PACKET_OTHERHOST) {
 699                 skb->pkt_type = PACKET_HOST;
 700                 nf_bridge->mask |= BRNF_PKT_TYPE;
 701         }
 702
 703         /* The physdev module checks on this */
 704         nf_bridge->mask |= BRNF_BRIDGED;
 705         nf_bridge->physoutdev = skb->dev;
 706
 707         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 708                 br_nf_forward_finish);
 709
 710         return NF_STOLEN;
 711 }
 712
 713 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 714                                       const struct net_device *in,
 715                                       const struct net_device *out,
 716                                       int (*okfn)(struct sk_buff *))
 717 {
 718         struct net_device **d = (struct net_device **)(skb->cb);
 719
 720 #ifdef CONFIG_SYSCTL
 721         if (!brnf_call_arptables)
 722                 return NF_ACCEPT;
 723 #endif
 724
 725         if (skb->protocol != htons(ETH_P_ARP)) {
 726                 if (!IS_VLAN_ARP(skb))
 727                         return NF_ACCEPT;
 728                 nf_bridge_pull_encap_header(skb);
 729         }
 730
 731         if (arp_hdr(skb)->ar_pln != 4) {
 732                 if (IS_VLAN_ARP(skb))
 733                         nf_bridge_push_encap_header(skb);
 734                 return NF_ACCEPT;
 735         }
 736         *d = (struct net_device *)in;
 737         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 738                 (struct net_device *)out, br_nf_forward_finish);
 739
 740         return NF_STOLEN;
 741 }
 742
 743 /* PF_BRIDGE/LOCAL_OUT ***********************************************
 744  *
 745  * This function sees both locally originated IP packets and forwarded
 746  * IP packets (in both cases the destination device is a bridge
 747  * device). It also sees bridged-and-DNAT'ed packets.
 748  *
 749  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 750  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 751  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 752  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 753  * will be executed.
 754  */
 755 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 756                                     const struct net_device *in,
 757                                     const struct net_device *out,
 758                                     int (*okfn)(struct sk_buff *))
 759 {
 760         struct net_device *realindev;
 761         struct nf_bridge_info *nf_bridge;
 762
 763         if (!skb->nf_bridge)
 764                 return NF_ACCEPT;
 765
 766         /* Need exclusive nf_bridge_info since we might have multiple
 767          * different physoutdevs. */
 768         if (!nf_bridge_unshare(skb))
 769                 return NF_DROP;
 770
 771         nf_bridge = skb->nf_bridge;
 772         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
 773                 return NF_ACCEPT;
 774
 775         /* Bridged, take PF_BRIDGE/FORWARD.
 776          * (see big note in front of br_nf_pre_routing_finish) */
 777         nf_bridge->physoutdev = skb->dev;
 778         realindev = nf_bridge->physindev;
 779
 780         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 781                 skb->pkt_type = PACKET_OTHERHOST;
 782                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 783         }
 784         nf_bridge_push_encap_header(skb);
 785
 786         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
 787                 br_forward_finish);
 788         return NF_STOLEN;
 789 }
 790
 791 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 792 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 793 {
 794         if (skb->nfct != NULL &&
 795             (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 796             skb->len > skb->dev->mtu &&
 797             !skb_is_gso(skb))
 798                 return ip_fragment(skb, br_dev_queue_push_xmit);
 799         else
 800                 return br_dev_queue_push_xmit(skb);
 801 }
 802 #else
 803 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 804 {
 805         return br_dev_queue_push_xmit(skb);
 806 }
 807 #endif
 808
 809 /* PF_BRIDGE/POST_ROUTING ********************************************/
 810 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 811                                        const struct net_device *in,
 812                                        const struct net_device *out,
 813                                        int (*okfn)(struct sk_buff *))
 814 {
 815         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 816         struct net_device *realoutdev = bridge_parent(skb->dev);
 817         u_int8_t pf;
 818
 819 #ifdef CONFIG_NETFILTER_DEBUG
 820         /* Be very paranoid. This probably won't happen anymore, but let's
 821          * keep the check just to be sure... */
 822         if (skb_mac_header(skb) < skb->head ||
 823             skb_mac_header(skb) + ETH_HLEN > skb->data) {
 824                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 825                        "bad mac.raw pointer.\n");
 826                 goto print_error;
 827         }
 828 #endif
 829
 830         if (!nf_bridge)
 831                 return NF_ACCEPT;
 832
 833         if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
 834                 return NF_ACCEPT;
 835
 836         if (!realoutdev)
 837                 return NF_DROP;
 838
 839         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 840             IS_PPPOE_IP(skb))
 841                 pf = PF_INET;
 842         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 843                  IS_PPPOE_IPV6(skb))
 844                 pf = PF_INET6;
 845         else
 846                 return NF_ACCEPT;
 847
 848 #ifdef CONFIG_NETFILTER_DEBUG
 849         if (skb->dst == NULL) {
 850                 printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
 851                 goto print_error;
 852         }
 853 #endif
 854
 855         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 856          * about the value of skb->pkt_type. */
 857         if (skb->pkt_type == PACKET_OTHERHOST) {
 858                 skb->pkt_type = PACKET_HOST;
 859                 nf_bridge->mask |= BRNF_PKT_TYPE;
 860         }
 861
 862         nf_bridge_pull_encap_header(skb);
 863         nf_bridge_save_header(skb);
 864
 865         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 866                 br_nf_dev_queue_xmit);
 867
 868         return NF_STOLEN;
 869
 870 #ifdef CONFIG_NETFILTER_DEBUG
 871 print_error:
 872         if (skb->dev != NULL) {
 873                 printk("[%s]", skb->dev->name);
 874                 if (realoutdev)
 875                         printk("[%s]", realoutdev->name);
 876         }
 877         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb),
 878                skb->data);
 879         dump_stack();
 880         return NF_ACCEPT;
 881 #endif
 882 }
 883
 884 /* IP/SABOTAGE *****************************************************/
 885 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 886  * for the second time. */
 887 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 888                                    const struct net_device *in,
 889                                    const struct net_device *out,
 890                                    int (*okfn)(struct sk_buff *))
 891 {
 892         if (skb->nf_bridge &&
 893             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 894                 return NF_STOP;
 895         }
 896
 897         return NF_ACCEPT;
 898 }
 899
 900 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 901  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 902  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 903  * ip_refrag() can return NF_STOLEN. */
 904 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 905         { .hook = br_nf_pre_routing,
 906           .owner = THIS_MODULE,
 907           .pf = PF_BRIDGE,
 908           .hooknum = NF_BR_PRE_ROUTING,
 909           .priority = NF_BR_PRI_BRNF, },
 910         { .hook = br_nf_local_in,
 911           .owner = THIS_MODULE,
 912           .pf = PF_BRIDGE,
 913           .hooknum = NF_BR_LOCAL_IN,
 914           .priority = NF_BR_PRI_BRNF, },
 915         { .hook = br_nf_forward_ip,
 916           .owner = THIS_MODULE,
 917           .pf = PF_BRIDGE,
 918           .hooknum = NF_BR_FORWARD,
 919           .priority = NF_BR_PRI_BRNF - 1, },
 920         { .hook = br_nf_forward_arp,
 921           .owner = THIS_MODULE,
 922           .pf = PF_BRIDGE,
 923           .hooknum = NF_BR_FORWARD,
 924           .priority = NF_BR_PRI_BRNF, },
 925         { .hook = br_nf_local_out,
 926           .owner = THIS_MODULE,
 927           .pf = PF_BRIDGE,
 928           .hooknum = NF_BR_LOCAL_OUT,
 929           .priority = NF_BR_PRI_FIRST, },
 930         { .hook = br_nf_post_routing,
 931           .owner = THIS_MODULE,
 932           .pf = PF_BRIDGE,
 933           .hooknum = NF_BR_POST_ROUTING,
 934           .priority = NF_BR_PRI_LAST, },
 935         { .hook = ip_sabotage_in,
 936           .owner = THIS_MODULE,
 937           .pf = PF_INET,
 938           .hooknum = NF_INET_PRE_ROUTING,
 939           .priority = NF_IP_PRI_FIRST, },
 940         { .hook = ip_sabotage_in,
 941           .owner = THIS_MODULE,
 942           .pf = PF_INET6,
 943           .hooknum = NF_INET_PRE_ROUTING,
 944           .priority = NF_IP6_PRI_FIRST, },
 945 };
 946
 947 #ifdef CONFIG_SYSCTL
 948 static
 949 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
 950                             void __user * buffer, size_t * lenp, loff_t * ppos)
 951 {
 952         int ret;
 953
 954         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 955
 956         if (write && *(int *)(ctl->data))
 957                 *(int *)(ctl->data) = 1;
 958         return ret;
 959 }
 960
 961 static ctl_table brnf_table[] = {
 962         {
 963                 .procname       = "bridge-nf-call-arptables",
 964                 .data           = &brnf_call_arptables,
 965                 .maxlen         = sizeof(int),
 966                 .mode           = 0644,
 967                 .proc_handler   = brnf_sysctl_call_tables,
 968         },
 969         {
 970                 .procname       = "bridge-nf-call-iptables",
 971                 .data           = &brnf_call_iptables,
 972                 .maxlen         = sizeof(int),
 973                 .mode           = 0644,
 974                 .proc_handler   = brnf_sysctl_call_tables,
 975         },
 976         {
 977                 .procname       = "bridge-nf-call-ip6tables",
 978                 .data           = &brnf_call_ip6tables,
 979                 .maxlen         = sizeof(int),
 980                 .mode           = 0644,
 981                 .proc_handler   = brnf_sysctl_call_tables,
 982         },
 983         {
 984                 .procname       = "bridge-nf-filter-vlan-tagged",
 985                 .data           = &brnf_filter_vlan_tagged,
 986                 .maxlen         = sizeof(int),
 987                 .mode           = 0644,
 988                 .proc_handler   = brnf_sysctl_call_tables,
 989         },
 990         {
 991                 .procname       = "bridge-nf-filter-pppoe-tagged",
 992                 .data           = &brnf_filter_pppoe_tagged,
 993                 .maxlen         = sizeof(int),
 994                 .mode           = 0644,
 995                 .proc_handler   = brnf_sysctl_call_tables,
 996         },
 997         { .ctl_name = 0 }
 998 };
 999
1000 static struct ctl_path brnf_path[] = {
1001         { .procname = "net", .ctl_name = CTL_NET, },
1002         { .procname = "bridge", .ctl_name = NET_BRIDGE, },
1003         { }
1004 };
1005 #endif
1006
1007 int __init br_netfilter_init(void)
1008 {
1009         int ret;
1010
1011         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1012         if (ret < 0)
1013                 return ret;
1014 #ifdef CONFIG_SYSCTL
1015         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1016         if (brnf_sysctl_header == NULL) {
1017                 printk(KERN_WARNING
1018                        "br_netfilter: can't register to sysctl.\n");
1019                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1020                 return -ENOMEM;
1021         }
1022 #endif
1023         printk(KERN_NOTICE "Bridge firewalling registered\n");
1024         return 0;
1025 }
1026
1027 void br_netfilter_fini(void)
1028 {
1029         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1030 #ifdef CONFIG_SYSCTL
1031         unregister_sysctl_table(brnf_sysctl_header);
1032 #endif
1033 }