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                <bdschuym@pandora.be>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Lennert dedicates this file to Kerstin Wurdinger.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/ip.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/if_arp.h>
  23 #include <linux/if_ether.h>
  24 #include <linux/if_vlan.h>
  25 #include <linux/if_pppox.h>
  26 #include <linux/ppp_defs.h>
  27 #include <linux/netfilter_bridge.h>
  28 #include <linux/netfilter_ipv4.h>
  29 #include <linux/netfilter_ipv6.h>
  30 #include <linux/netfilter_arp.h>
  31 #include <linux/in_route.h>
  32 #include <linux/inetdevice.h>
  33
  34 #include <net/ip.h>
  35 #include <net/ipv6.h>
  36 #include <net/route.h>
  37
  38 #include <asm/uaccess.h>
  39 #include "br_private.h"
  40 #ifdef CONFIG_SYSCTL
  41 #include <linux/sysctl.h>
  42 #endif
  43
  44 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  45                                  (skb->nf_bridge->data))->daddr.ipv4)
  46 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  47 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  48
  49 #ifdef CONFIG_SYSCTL
  50 static struct ctl_table_header *brnf_sysctl_header;
  51 static int brnf_call_iptables __read_mostly = 1;
  52 static int brnf_call_ip6tables __read_mostly = 1;
  53 static int brnf_call_arptables __read_mostly = 1;
  54 static int brnf_filter_vlan_tagged __read_mostly = 0;
  55 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  56 #else
  57 #define brnf_filter_vlan_tagged 0
  58 #define brnf_filter_pppoe_tagged 0
  59 #endif
  60
  61 static inline __be16 vlan_proto(const struct sk_buff *skb)
  62 {
  63         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  64 }
  65
  66 #define IS_VLAN_IP(skb) \
  67         (skb->protocol == htons(ETH_P_8021Q) && \
  68          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  69          brnf_filter_vlan_tagged)
  70
  71 #define IS_VLAN_IPV6(skb) \
  72         (skb->protocol == htons(ETH_P_8021Q) && \
  73          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  74          brnf_filter_vlan_tagged)
  75
  76 #define IS_VLAN_ARP(skb) \
  77         (skb->protocol == htons(ETH_P_8021Q) && \
  78          vlan_proto(skb) == htons(ETH_P_ARP) && \
  79          brnf_filter_vlan_tagged)
  80
  81 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  82 {
  83         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  84                             sizeof(struct pppoe_hdr)));
  85 }
  86
  87 #define IS_PPPOE_IP(skb) \
  88         (skb->protocol == htons(ETH_P_PPP_SES) && \
  89          pppoe_proto(skb) == htons(PPP_IP) && \
  90          brnf_filter_pppoe_tagged)
  91
  92 #define IS_PPPOE_IPV6(skb) \
  93         (skb->protocol == htons(ETH_P_PPP_SES) && \
  94          pppoe_proto(skb) == htons(PPP_IPV6) && \
  95          brnf_filter_pppoe_tagged)
  96
  97 static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
  98 {
  99 }
 100
 101 static struct dst_ops fake_dst_ops = {
 102         .family =               AF_INET,
 103         .protocol =             cpu_to_be16(ETH_P_IP),
 104         .update_pmtu =          fake_update_pmtu,
 105         .entries =              ATOMIC_INIT(0),
 106 };
 107
 108 /*
 109  * Initialize bogus route table used to keep netfilter happy.
 110  * Currently, we fill in the PMTU entry because netfilter
 111  * refragmentation needs it, and the rt_flags entry because
 112  * ipt_REJECT needs it.  Future netfilter modules might
 113  * require us to fill additional fields.
 114  */
 115 void br_netfilter_rtable_init(struct net_bridge *br)
 116 {
 117         struct rtable *rt = &br->fake_rtable;
 118
 119         atomic_set(&rt->u.dst.__refcnt, 1);
 120         rt->u.dst.dev = br->dev;
 121         rt->u.dst.path = &rt->u.dst;
 122         rt->u.dst.metrics[RTAX_MTU - 1] = 1500;
 123         rt->u.dst.flags = DST_NOXFRM;
 124         rt->u.dst.ops = &fake_dst_ops;
 125 }
 126
 127 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 128 {
 129         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 130
 131         return port ? &port->br->fake_rtable : NULL;
 132 }
 133
 134 static inline struct net_device *bridge_parent(const struct net_device *dev)
 135 {
 136         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 137
 138         return port ? port->br->dev : NULL;
 139 }
 140
 141 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 142 {
 143         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 144         if (likely(skb->nf_bridge))
 145                 atomic_set(&(skb->nf_bridge->use), 1);
 146
 147         return skb->nf_bridge;
 148 }
 149
 150 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 151 {
 152         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 153
 154         if (atomic_read(&nf_bridge->use) > 1) {
 155                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 156
 157                 if (tmp) {
 158                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 159                         atomic_set(&tmp->use, 1);
 160                         nf_bridge_put(nf_bridge);
 161                 }
 162                 nf_bridge = tmp;
 163         }
 164         return nf_bridge;
 165 }
 166
 167 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 168 {
 169         unsigned int len = nf_bridge_encap_header_len(skb);
 170
 171         skb_push(skb, len);
 172         skb->network_header -= len;
 173 }
 174
 175 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 176 {
 177         unsigned int len = nf_bridge_encap_header_len(skb);
 178
 179         skb_pull(skb, len);
 180         skb->network_header += len;
 181 }
 182
 183 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 184 {
 185         unsigned int len = nf_bridge_encap_header_len(skb);
 186
 187         skb_pull_rcsum(skb, len);
 188         skb->network_header += len;
 189 }
 190
 191 static inline void nf_bridge_save_header(struct sk_buff *skb)
 192 {
 193         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 194
 195         skb_copy_from_linear_data_offset(skb, -header_size,
 196                                          skb->nf_bridge->data, header_size);
 197 }
 198
 199 /*
 200  * When forwarding bridge frames, we save a copy of the original
 201  * header before processing.
 202  */
 203 int nf_bridge_copy_header(struct sk_buff *skb)
 204 {
 205         int err;
 206         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 207
 208         err = skb_cow_head(skb, header_size);
 209         if (err)
 210                 return err;
 211
 212         skb_copy_to_linear_data_offset(skb, -header_size,
 213                                        skb->nf_bridge->data, header_size);
 214         __skb_push(skb, nf_bridge_encap_header_len(skb));
 215         return 0;
 216 }
 217
 218 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 219 /* Undo the changes made for ip6tables PREROUTING and continue the
 220  * bridge PRE_ROUTING hook. */
 221 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 222 {
 223         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 224         struct rtable *rt;
 225
 226         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 227                 skb->pkt_type = PACKET_OTHERHOST;
 228                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 229         }
 230         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 231
 232         rt = bridge_parent_rtable(nf_bridge->physindev);
 233         if (!rt) {
 234                 kfree_skb(skb);
 235                 return 0;
 236         }
 237         dst_hold(&rt->u.dst);
 238         skb_dst_set(skb, &rt->u.dst);
 239
 240         skb->dev = nf_bridge->physindev;
 241         nf_bridge_push_encap_header(skb);
 242         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 243                        br_handle_frame_finish, 1);
 244
 245         return 0;
 246 }
 247
 248 /* This requires some explaining. If DNAT has taken place,
 249  * we will need to fix up the destination Ethernet address.
 250  *
 251  * There are two cases to consider:
 252  * 1. The packet was DNAT'ed to a device in the same bridge
 253  *    port group as it was received on. We can still bridge
 254  *    the packet.
 255  * 2. The packet was DNAT'ed to a different device, either
 256  *    a non-bridged device or another bridge port group.
 257  *    The packet will need to be routed.
 258  *
 259  * The correct way of distinguishing between these two cases is to
 260  * call ip_route_input() and to look at skb->dst->dev, which is
 261  * changed to the destination device if ip_route_input() succeeds.
 262  *
 263  * Let's first consider the case that ip_route_input() succeeds:
 264  *
 265  * If the output device equals the logical bridge device the packet
 266  * came in on, we can consider this bridging. The corresponding MAC
 267  * address will be obtained in br_nf_pre_routing_finish_bridge.
 268  * Otherwise, the packet is considered to be routed and we just
 269  * change the destination MAC address so that the packet will
 270  * later be passed up to the IP stack to be routed. For a redirected
 271  * packet, ip_route_input() will give back the localhost as output device,
 272  * which differs from the bridge device.
 273  *
 274  * Let's now consider the case that ip_route_input() fails:
 275  *
 276  * This can be because the destination address is martian, in which case
 277  * the packet will be dropped.
 278  * If IP forwarding is disabled, ip_route_input() will fail, while
 279  * ip_route_output_key() can return success. The source
 280  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 281  * thinks we're handling a locally generated packet and won't care
 282  * if IP forwarding is enabled. If the output device equals the logical bridge
 283  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 284  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 285  */
 286
 287 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 288 {
 289         skb->dev = bridge_parent(skb->dev);
 290         if (skb->dev) {
 291                 struct dst_entry *dst = skb_dst(skb);
 292
 293                 nf_bridge_pull_encap_header(skb);
 294                 skb->nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 295
 296                 if (dst->hh)
 297                         return neigh_hh_output(dst->hh, skb);
 298                 else if (dst->neighbour)
 299                         return dst->neighbour->output(skb);
 300         }
 301         kfree_skb(skb);
 302         return 0;
 303 }
 304
 305 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 306 {
 307         struct net_device *dev = skb->dev;
 308         struct iphdr *iph = ip_hdr(skb);
 309         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 310         struct rtable *rt;
 311         int err;
 312
 313         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 314                 skb->pkt_type = PACKET_OTHERHOST;
 315                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 316         }
 317         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 318         if (dnat_took_place(skb)) {
 319                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 320                         struct flowi fl = {
 321                                 .nl_u = {
 322                                         .ip4_u = {
 323                                                  .daddr = iph->daddr,
 324                                                  .saddr = 0,
 325                                                  .tos = RT_TOS(iph->tos) },
 326                                 },
 327                                 .proto = 0,
 328                         };
 329                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 330
 331                         /* If err equals -EHOSTUNREACH the error is due to a
 332                          * martian destination or due to the fact that
 333                          * forwarding is disabled. For most martian packets,
 334                          * ip_route_output_key() will fail. It won't fail for 2 types of
 335                          * martian destinations: loopback destinations and destination
 336                          * 0.0.0.0. In both cases the packet will be dropped because the
 337                          * destination is the loopback device and not the bridge. */
 338                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 339                                 goto free_skb;
 340
 341                         if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 342                                 /* - Bridged-and-DNAT'ed traffic doesn't
 343                                  *   require ip_forwarding. */
 344                                 if (((struct dst_entry *)rt)->dev == dev) {
 345                                         skb_dst_set(skb, (struct dst_entry *)rt);
 346                                         goto bridged_dnat;
 347                                 }
 348                                 dst_release((struct dst_entry *)rt);
 349                         }
 350 free_skb:
 351                         kfree_skb(skb);
 352                         return 0;
 353                 } else {
 354                         if (skb_dst(skb)->dev == dev) {
 355 bridged_dnat:
 356                                 skb->dev = nf_bridge->physindev;
 357                                 nf_bridge_push_encap_header(skb);
 358                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 359                                                NF_BR_PRE_ROUTING,
 360                                                skb, skb->dev, NULL,
 361                                                br_nf_pre_routing_finish_bridge,
 362                                                1);
 363                                 return 0;
 364                         }
 365                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 366                         skb->pkt_type = PACKET_HOST;
 367                 }
 368         } else {
 369                 rt = bridge_parent_rtable(nf_bridge->physindev);
 370                 if (!rt) {
 371                         kfree_skb(skb);
 372                         return 0;
 373                 }
 374                 dst_hold(&rt->u.dst);
 375                 skb_dst_set(skb, &rt->u.dst);
 376         }
 377
 378         skb->dev = nf_bridge->physindev;
 379         nf_bridge_push_encap_header(skb);
 380         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 381                        br_handle_frame_finish, 1);
 382
 383         return 0;
 384 }
 385
 386 /* Some common code for IPv4/IPv6 */
 387 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 388 {
 389         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 390
 391         if (skb->pkt_type == PACKET_OTHERHOST) {
 392                 skb->pkt_type = PACKET_HOST;
 393                 nf_bridge->mask |= BRNF_PKT_TYPE;
 394         }
 395
 396         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 397         nf_bridge->physindev = skb->dev;
 398         skb->dev = bridge_parent(skb->dev);
 399
 400         return skb->dev;
 401 }
 402
 403 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 404 static int check_hbh_len(struct sk_buff *skb)
 405 {
 406         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 407         u32 pkt_len;
 408         const unsigned char *nh = skb_network_header(skb);
 409         int off = raw - nh;
 410         int len = (raw[1] + 1) << 3;
 411
 412         if ((raw + len) - skb->data > skb_headlen(skb))
 413                 goto bad;
 414
 415         off += 2;
 416         len -= 2;
 417
 418         while (len > 0) {
 419                 int optlen = nh[off + 1] + 2;
 420
 421                 switch (nh[off]) {
 422                 case IPV6_TLV_PAD0:
 423                         optlen = 1;
 424                         break;
 425
 426                 case IPV6_TLV_PADN:
 427                         break;
 428
 429                 case IPV6_TLV_JUMBO:
 430                         if (nh[off + 1] != 4 || (off & 3) != 2)
 431                                 goto bad;
 432                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 433                         if (pkt_len <= IPV6_MAXPLEN ||
 434                             ipv6_hdr(skb)->payload_len)
 435                                 goto bad;
 436                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 437                                 goto bad;
 438                         if (pskb_trim_rcsum(skb,
 439                                             pkt_len + sizeof(struct ipv6hdr)))
 440                                 goto bad;
 441                         nh = skb_network_header(skb);
 442                         break;
 443                 default:
 444                         if (optlen > len)
 445                                 goto bad;
 446                         break;
 447                 }
 448                 off += optlen;
 449                 len -= optlen;
 450         }
 451         if (len == 0)
 452                 return 0;
 453 bad:
 454         return -1;
 455
 456 }
 457
 458 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 459  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 460 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 461                                            struct sk_buff *skb,
 462                                            const struct net_device *in,
 463                                            const struct net_device *out,
 464                                            int (*okfn)(struct sk_buff *))
 465 {
 466         struct ipv6hdr *hdr;
 467         u32 pkt_len;
 468
 469         if (skb->len < sizeof(struct ipv6hdr))
 470                 goto inhdr_error;
 471
 472         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 473                 goto inhdr_error;
 474
 475         hdr = ipv6_hdr(skb);
 476
 477         if (hdr->version != 6)
 478                 goto inhdr_error;
 479
 480         pkt_len = ntohs(hdr->payload_len);
 481
 482         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 483                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 484                         goto inhdr_error;
 485                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 486                         goto inhdr_error;
 487         }
 488         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 489                 goto inhdr_error;
 490
 491         nf_bridge_put(skb->nf_bridge);
 492         if (!nf_bridge_alloc(skb))
 493                 return NF_DROP;
 494         if (!setup_pre_routing(skb))
 495                 return NF_DROP;
 496
 497         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 498                 br_nf_pre_routing_finish_ipv6);
 499
 500         return NF_STOLEN;
 501
 502 inhdr_error:
 503         return NF_DROP;
 504 }
 505
 506 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 507  * Replicate the checks that IPv4 does on packet reception.
 508  * Set skb->dev to the bridge device (i.e. parent of the
 509  * receiving device) to make netfilter happy, the REDIRECT
 510  * target in particular.  Save the original destination IP
 511  * address to be able to detect DNAT afterwards. */
 512 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 513                                       const struct net_device *in,
 514                                       const struct net_device *out,
 515                                       int (*okfn)(struct sk_buff *))
 516 {
 517         struct iphdr *iph;
 518         __u32 len = nf_bridge_encap_header_len(skb);
 519
 520         if (unlikely(!pskb_may_pull(skb, len)))
 521                 goto out;
 522
 523         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 524             IS_PPPOE_IPV6(skb)) {
 525 #ifdef CONFIG_SYSCTL
 526                 if (!brnf_call_ip6tables)
 527                         return NF_ACCEPT;
 528 #endif
 529                 nf_bridge_pull_encap_header_rcsum(skb);
 530                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 531         }
 532 #ifdef CONFIG_SYSCTL
 533         if (!brnf_call_iptables)
 534                 return NF_ACCEPT;
 535 #endif
 536
 537         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 538             !IS_PPPOE_IP(skb))
 539                 return NF_ACCEPT;
 540
 541         nf_bridge_pull_encap_header_rcsum(skb);
 542
 543         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 544                 goto inhdr_error;
 545
 546         iph = ip_hdr(skb);
 547         if (iph->ihl < 5 || iph->version != 4)
 548                 goto inhdr_error;
 549
 550         if (!pskb_may_pull(skb, 4 * iph->ihl))
 551                 goto inhdr_error;
 552
 553         iph = ip_hdr(skb);
 554         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 555                 goto inhdr_error;
 556
 557         len = ntohs(iph->tot_len);
 558         if (skb->len < len || len < 4 * iph->ihl)
 559                 goto inhdr_error;
 560
 561         pskb_trim_rcsum(skb, len);
 562
 563         nf_bridge_put(skb->nf_bridge);
 564         if (!nf_bridge_alloc(skb))
 565                 return NF_DROP;
 566         if (!setup_pre_routing(skb))
 567                 return NF_DROP;
 568         store_orig_dstaddr(skb);
 569
 570         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 571                 br_nf_pre_routing_finish);
 572
 573         return NF_STOLEN;
 574
 575 inhdr_error:
 576 //      IP_INC_STATS_BH(IpInHdrErrors);
 577 out:
 578         return NF_DROP;
 579 }
 580
 581
 582 /* PF_BRIDGE/LOCAL_IN ************************************************/
 583 /* The packet is locally destined, which requires a real
 584  * dst_entry, so detach the fake one.  On the way up, the
 585  * packet would pass through PRE_ROUTING again (which already
 586  * took place when the packet entered the bridge), but we
 587  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 588  * prevent this from happening. */
 589 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 590                                    const struct net_device *in,
 591                                    const struct net_device *out,
 592                                    int (*okfn)(struct sk_buff *))
 593 {
 594         struct rtable *rt = skb_rtable(skb);
 595
 596         if (rt && rt == bridge_parent_rtable(in))
 597                 skb_dst_drop(skb);
 598
 599         return NF_ACCEPT;
 600 }
 601
 602 /* PF_BRIDGE/FORWARD *************************************************/
 603 static int br_nf_forward_finish(struct sk_buff *skb)
 604 {
 605         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 606         struct net_device *in;
 607
 608         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 609                 in = nf_bridge->physindev;
 610                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 611                         skb->pkt_type = PACKET_OTHERHOST;
 612                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 613                 }
 614         } else {
 615                 in = *((struct net_device **)(skb->cb));
 616         }
 617         nf_bridge_push_encap_header(skb);
 618         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 619                        skb->dev, br_forward_finish, 1);
 620         return 0;
 621 }
 622
 623 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 624  * netfilter with indev and outdev set to the bridge device,
 625  * but we are still able to filter on the 'real' indev/outdev
 626  * because of the physdev module. For ARP, indev and outdev are the
 627  * bridge ports. */
 628 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 629                                      const struct net_device *in,
 630                                      const struct net_device *out,
 631                                      int (*okfn)(struct sk_buff *))
 632 {
 633         struct nf_bridge_info *nf_bridge;
 634         struct net_device *parent;
 635         u_int8_t pf;
 636
 637         if (!skb->nf_bridge)
 638                 return NF_ACCEPT;
 639
 640         /* Need exclusive nf_bridge_info since we might have multiple
 641          * different physoutdevs. */
 642         if (!nf_bridge_unshare(skb))
 643                 return NF_DROP;
 644
 645         parent = bridge_parent(out);
 646         if (!parent)
 647                 return NF_DROP;
 648
 649         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 650             IS_PPPOE_IP(skb))
 651                 pf = PF_INET;
 652         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 653                  IS_PPPOE_IPV6(skb))
 654                 pf = PF_INET6;
 655         else
 656                 return NF_ACCEPT;
 657
 658         nf_bridge_pull_encap_header(skb);
 659
 660         nf_bridge = skb->nf_bridge;
 661         if (skb->pkt_type == PACKET_OTHERHOST) {
 662                 skb->pkt_type = PACKET_HOST;
 663                 nf_bridge->mask |= BRNF_PKT_TYPE;
 664         }
 665
 666         /* The physdev module checks on this */
 667         nf_bridge->mask |= BRNF_BRIDGED;
 668         nf_bridge->physoutdev = skb->dev;
 669
 670         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 671                 br_nf_forward_finish);
 672
 673         return NF_STOLEN;
 674 }
 675
 676 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 677                                       const struct net_device *in,
 678                                       const struct net_device *out,
 679                                       int (*okfn)(struct sk_buff *))
 680 {
 681         struct net_device **d = (struct net_device **)(skb->cb);
 682
 683 #ifdef CONFIG_SYSCTL
 684         if (!brnf_call_arptables)
 685                 return NF_ACCEPT;
 686 #endif
 687
 688         if (skb->protocol != htons(ETH_P_ARP)) {
 689                 if (!IS_VLAN_ARP(skb))
 690                         return NF_ACCEPT;
 691                 nf_bridge_pull_encap_header(skb);
 692         }
 693
 694         if (arp_hdr(skb)->ar_pln != 4) {
 695                 if (IS_VLAN_ARP(skb))
 696                         nf_bridge_push_encap_header(skb);
 697                 return NF_ACCEPT;
 698         }
 699         *d = (struct net_device *)in;
 700         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 701                 (struct net_device *)out, br_nf_forward_finish);
 702
 703         return NF_STOLEN;
 704 }
 705
 706 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 707 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 708 {
 709         if (skb->nfct != NULL &&
 710             (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 711             skb->len > skb->dev->mtu &&
 712             !skb_is_gso(skb))
 713                 return ip_fragment(skb, br_dev_queue_push_xmit);
 714         else
 715                 return br_dev_queue_push_xmit(skb);
 716 }
 717 #else
 718 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 719 {
 720         return br_dev_queue_push_xmit(skb);
 721 }
 722 #endif
 723
 724 /* PF_BRIDGE/POST_ROUTING ********************************************/
 725 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 726                                        const struct net_device *in,
 727                                        const struct net_device *out,
 728                                        int (*okfn)(struct sk_buff *))
 729 {
 730         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 731         struct net_device *realoutdev = bridge_parent(skb->dev);
 732         u_int8_t pf;
 733
 734         if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 735                 return NF_ACCEPT;
 736
 737         if (!realoutdev)
 738                 return NF_DROP;
 739
 740         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 741             IS_PPPOE_IP(skb))
 742                 pf = PF_INET;
 743         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 744                  IS_PPPOE_IPV6(skb))
 745                 pf = PF_INET6;
 746         else
 747                 return NF_ACCEPT;
 748
 749         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 750          * about the value of skb->pkt_type. */
 751         if (skb->pkt_type == PACKET_OTHERHOST) {
 752                 skb->pkt_type = PACKET_HOST;
 753                 nf_bridge->mask |= BRNF_PKT_TYPE;
 754         }
 755
 756         nf_bridge_pull_encap_header(skb);
 757         nf_bridge_save_header(skb);
 758
 759         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 760                 br_nf_dev_queue_xmit);
 761
 762         return NF_STOLEN;
 763 }
 764
 765 /* IP/SABOTAGE *****************************************************/
 766 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 767  * for the second time. */
 768 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 769                                    const struct net_device *in,
 770                                    const struct net_device *out,
 771                                    int (*okfn)(struct sk_buff *))
 772 {
 773         if (skb->nf_bridge &&
 774             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 775                 return NF_STOP;
 776         }
 777
 778         return NF_ACCEPT;
 779 }
 780
 781 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 782  * br_dev_queue_push_xmit is called afterwards */
 783 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 784         {
 785                 .hook = br_nf_pre_routing,
 786                 .owner = THIS_MODULE,
 787                 .pf = PF_BRIDGE,
 788                 .hooknum = NF_BR_PRE_ROUTING,
 789                 .priority = NF_BR_PRI_BRNF,
 790         },
 791         {
 792                 .hook = br_nf_local_in,
 793                 .owner = THIS_MODULE,
 794                 .pf = PF_BRIDGE,
 795                 .hooknum = NF_BR_LOCAL_IN,
 796                 .priority = NF_BR_PRI_BRNF,
 797         },
 798         {
 799                 .hook = br_nf_forward_ip,
 800                 .owner = THIS_MODULE,
 801                 .pf = PF_BRIDGE,
 802                 .hooknum = NF_BR_FORWARD,
 803                 .priority = NF_BR_PRI_BRNF - 1,
 804         },
 805         {
 806                 .hook = br_nf_forward_arp,
 807                 .owner = THIS_MODULE,
 808                 .pf = PF_BRIDGE,
 809                 .hooknum = NF_BR_FORWARD,
 810                 .priority = NF_BR_PRI_BRNF,
 811         },
 812         {
 813                 .hook = br_nf_post_routing,
 814                 .owner = THIS_MODULE,
 815                 .pf = PF_BRIDGE,
 816                 .hooknum = NF_BR_POST_ROUTING,
 817                 .priority = NF_BR_PRI_LAST,
 818         },
 819         {
 820                 .hook = ip_sabotage_in,
 821                 .owner = THIS_MODULE,
 822                 .pf = PF_INET,
 823                 .hooknum = NF_INET_PRE_ROUTING,
 824                 .priority = NF_IP_PRI_FIRST,
 825         },
 826         {
 827                 .hook = ip_sabotage_in,
 828                 .owner = THIS_MODULE,
 829                 .pf = PF_INET6,
 830                 .hooknum = NF_INET_PRE_ROUTING,
 831                 .priority = NF_IP6_PRI_FIRST,
 832         },
 833 };
 834
 835 #ifdef CONFIG_SYSCTL
 836 static
 837 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 838                             void __user * buffer, size_t * lenp, loff_t * ppos)
 839 {
 840         int ret;
 841
 842         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 843
 844         if (write && *(int *)(ctl->data))
 845                 *(int *)(ctl->data) = 1;
 846         return ret;
 847 }
 848
 849 static ctl_table brnf_table[] = {
 850         {
 851                 .procname       = "bridge-nf-call-arptables",
 852                 .data           = &brnf_call_arptables,
 853                 .maxlen         = sizeof(int),
 854                 .mode           = 0644,
 855                 .proc_handler   = brnf_sysctl_call_tables,
 856         },
 857         {
 858                 .procname       = "bridge-nf-call-iptables",
 859                 .data           = &brnf_call_iptables,
 860                 .maxlen         = sizeof(int),
 861                 .mode           = 0644,
 862                 .proc_handler   = brnf_sysctl_call_tables,
 863         },
 864         {
 865                 .procname       = "bridge-nf-call-ip6tables",
 866                 .data           = &brnf_call_ip6tables,
 867                 .maxlen         = sizeof(int),
 868                 .mode           = 0644,
 869                 .proc_handler   = brnf_sysctl_call_tables,
 870         },
 871         {
 872                 .procname       = "bridge-nf-filter-vlan-tagged",
 873                 .data           = &brnf_filter_vlan_tagged,
 874                 .maxlen         = sizeof(int),
 875                 .mode           = 0644,
 876                 .proc_handler   = brnf_sysctl_call_tables,
 877         },
 878         {
 879                 .procname       = "bridge-nf-filter-pppoe-tagged",
 880                 .data           = &brnf_filter_pppoe_tagged,
 881                 .maxlen         = sizeof(int),
 882                 .mode           = 0644,
 883                 .proc_handler   = brnf_sysctl_call_tables,
 884         },
 885         { }
 886 };
 887
 888 static struct ctl_path brnf_path[] = {
 889         { .procname = "net", },
 890         { .procname = "bridge", },
 891         { }
 892 };
 893 #endif
 894
 895 int __init br_netfilter_init(void)
 896 {
 897         int ret;
 898
 899         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 900         if (ret < 0)
 901                 return ret;
 902 #ifdef CONFIG_SYSCTL
 903         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
 904         if (brnf_sysctl_header == NULL) {
 905                 printk(KERN_WARNING
 906                        "br_netfilter: can't register to sysctl.\n");
 907                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 908                 return -ENOMEM;
 909         }
 910 #endif
 911         printk(KERN_NOTICE "Bridge firewalling registered\n");
 912         return 0;
 913 }
 914
 915 void br_netfilter_fini(void)
 916 {
 917         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 918 #ifdef CONFIG_SYSCTL
 919         unregister_sysctl_table(brnf_sysctl_header);
 920 #endif
 921 }