net/bridge/br_netfilter.c

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