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/slab.h>
  20 #include <linux/ip.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/if_ether.h>
  25 #include <linux/if_vlan.h>
  26 #include <linux/if_pppox.h>
  27 #include <linux/ppp_defs.h>
  28 #include <linux/netfilter_bridge.h>
  29 #include <linux/netfilter_ipv4.h>
  30 #include <linux/netfilter_ipv6.h>
  31 #include <linux/netfilter_arp.h>
  32 #include <linux/in_route.h>
  33 #include <linux/inetdevice.h>
  34
  35 #include <net/ip.h>
  36 #include <net/ipv6.h>
  37 #include <net/route.h>
  38
  39 #include <asm/uaccess.h>
  40 #include "br_private.h"
  41 #ifdef CONFIG_SYSCTL
  42 #include <linux/sysctl.h>
  43 #endif
  44
  45 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  46                                  (skb->nf_bridge->data))->daddr.ipv4)
  47 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  48 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  49
  50 #ifdef CONFIG_SYSCTL
  51 static struct ctl_table_header *brnf_sysctl_header;
  52 static int brnf_call_iptables __read_mostly = 1;
  53 static int brnf_call_ip6tables __read_mostly = 1;
  54 static int brnf_call_arptables __read_mostly = 1;
  55 static int brnf_filter_vlan_tagged __read_mostly = 0;
  56 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  57 #else
  58 #define brnf_call_iptables 1
  59 #define brnf_call_ip6tables 1
  60 #define brnf_call_arptables 1
  61 #define brnf_filter_vlan_tagged 0
  62 #define brnf_filter_pppoe_tagged 0
  63 #endif
  64
  65 static inline __be16 vlan_proto(const struct sk_buff *skb)
  66 {
  67         if (vlan_tx_tag_present(skb))
  68                 return skb->protocol;
  69         else if (skb->protocol == htons(ETH_P_8021Q))
  70                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  71         else
  72                 return 0;
  73 }
  74
  75 #define IS_VLAN_IP(skb) \
  76         (vlan_proto(skb) == htons(ETH_P_IP) && \
  77          brnf_filter_vlan_tagged)
  78
  79 #define IS_VLAN_IPV6(skb) \
  80         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  81          brnf_filter_vlan_tagged)
  82
  83 #define IS_VLAN_ARP(skb) \
  84         (vlan_proto(skb) == htons(ETH_P_ARP) && \
  85          brnf_filter_vlan_tagged)
  86
  87 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  88 {
  89         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  90                             sizeof(struct pppoe_hdr)));
  91 }
  92
  93 #define IS_PPPOE_IP(skb) \
  94         (skb->protocol == htons(ETH_P_PPP_SES) && \
  95          pppoe_proto(skb) == htons(PPP_IP) && \
  96          brnf_filter_pppoe_tagged)
  97
  98 #define IS_PPPOE_IPV6(skb) \
  99         (skb->protocol == htons(ETH_P_PPP_SES) && \
 100          pppoe_proto(skb) == htons(PPP_IPV6) && \
 101          brnf_filter_pppoe_tagged)
 102
 103 static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
 104 {
 105 }
 106
 107 static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
 108 {
 109         return NULL;
 110 }
 111
 112 static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 113 {
 114         return NULL;
 115 }
 116
 117 static unsigned int fake_mtu(const struct dst_entry *dst)
 118 {
 119         return dst->dev->mtu;
 120 }
 121
 122 static struct dst_ops fake_dst_ops = {
 123         .family =               AF_INET,
 124         .protocol =             cpu_to_be16(ETH_P_IP),
 125         .update_pmtu =          fake_update_pmtu,
 126         .cow_metrics =          fake_cow_metrics,
 127         .neigh_lookup =         fake_neigh_lookup,
 128         .mtu =                  fake_mtu,
 129 };
 130
 131 /*
 132  * Initialize bogus route table used to keep netfilter happy.
 133  * Currently, we fill in the PMTU entry because netfilter
 134  * refragmentation needs it, and the rt_flags entry because
 135  * ipt_REJECT needs it.  Future netfilter modules might
 136  * require us to fill additional fields.
 137  */
 138 static const u32 br_dst_default_metrics[RTAX_MAX] = {
 139         [RTAX_MTU - 1] = 1500,
 140 };
 141
 142 void br_netfilter_rtable_init(struct net_bridge *br)
 143 {
 144         struct rtable *rt = &br->fake_rtable;
 145
 146         atomic_set(&rt->dst.__refcnt, 1);
 147         rt->dst.dev = br->dev;
 148         rt->dst.path = &rt->dst;
 149         dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
 150         rt->dst.flags   = DST_NOXFRM | DST_NOPEER;
 151         rt->dst.ops = &fake_dst_ops;
 152 }
 153
 154 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 155 {
 156         struct net_bridge_port *port;
 157
 158         port = br_port_get_rcu(dev);
 159         return port ? &port->br->fake_rtable : NULL;
 160 }
 161
 162 static inline struct net_device *bridge_parent(const struct net_device *dev)
 163 {
 164         struct net_bridge_port *port;
 165
 166         port = br_port_get_rcu(dev);
 167         return port ? port->br->dev : NULL;
 168 }
 169
 170 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 171 {
 172         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 173         if (likely(skb->nf_bridge))
 174                 atomic_set(&(skb->nf_bridge->use), 1);
 175
 176         return skb->nf_bridge;
 177 }
 178
 179 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 180 {
 181         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 182
 183         if (atomic_read(&nf_bridge->use) > 1) {
 184                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 185
 186                 if (tmp) {
 187                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 188                         atomic_set(&tmp->use, 1);
 189                 }
 190                 nf_bridge_put(nf_bridge);
 191                 nf_bridge = tmp;
 192         }
 193         return nf_bridge;
 194 }
 195
 196 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 197 {
 198         unsigned int len = nf_bridge_encap_header_len(skb);
 199
 200         skb_push(skb, len);
 201         skb->network_header -= len;
 202 }
 203
 204 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 205 {
 206         unsigned int len = nf_bridge_encap_header_len(skb);
 207
 208         skb_pull(skb, len);
 209         skb->network_header += len;
 210 }
 211
 212 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 213 {
 214         unsigned int len = nf_bridge_encap_header_len(skb);
 215
 216         skb_pull_rcsum(skb, len);
 217         skb->network_header += len;
 218 }
 219
 220 static inline void nf_bridge_save_header(struct sk_buff *skb)
 221 {
 222         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 223
 224         skb_copy_from_linear_data_offset(skb, -header_size,
 225                                          skb->nf_bridge->data, header_size);
 226 }
 227
 228 static inline void nf_bridge_update_protocol(struct sk_buff *skb)
 229 {
 230         if (skb->nf_bridge->mask & BRNF_8021Q)
 231                 skb->protocol = htons(ETH_P_8021Q);
 232         else if (skb->nf_bridge->mask & BRNF_PPPoE)
 233                 skb->protocol = htons(ETH_P_PPP_SES);
 234 }
 235
 236 /* When handing a packet over to the IP layer
 237  * check whether we have a skb that is in the
 238  * expected format
 239  */
 240
 241 static int br_parse_ip_options(struct sk_buff *skb)
 242 {
 243         struct ip_options *opt;
 244         const struct iphdr *iph;
 245         struct net_device *dev = skb->dev;
 246         u32 len;
 247
 248         iph = ip_hdr(skb);
 249         opt = &(IPCB(skb)->opt);
 250
 251         /* Basic sanity checks */
 252         if (iph->ihl < 5 || iph->version != 4)
 253                 goto inhdr_error;
 254
 255         if (!pskb_may_pull(skb, iph->ihl*4))
 256                 goto inhdr_error;
 257
 258         iph = ip_hdr(skb);
 259         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 260                 goto inhdr_error;
 261
 262         len = ntohs(iph->tot_len);
 263         if (skb->len < len) {
 264                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 265                 goto drop;
 266         } else if (len < (iph->ihl*4))
 267                 goto inhdr_error;
 268
 269         if (pskb_trim_rcsum(skb, len)) {
 270                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 271                 goto drop;
 272         }
 273
 274         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 275         if (iph->ihl == 5)
 276                 return 0;
 277
 278         opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 279         if (ip_options_compile(dev_net(dev), opt, skb))
 280                 goto inhdr_error;
 281
 282         /* Check correct handling of SRR option */
 283         if (unlikely(opt->srr)) {
 284                 struct in_device *in_dev = __in_dev_get_rcu(dev);
 285                 if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
 286                         goto drop;
 287
 288                 if (ip_options_rcv_srr(skb))
 289                         goto drop;
 290         }
 291
 292         return 0;
 293
 294 inhdr_error:
 295         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 296 drop:
 297         return -1;
 298 }
 299
 300 /* Fill in the header for fragmented IP packets handled by
 301  * the IPv4 connection tracking code.
 302  */
 303 int nf_bridge_copy_header(struct sk_buff *skb)
 304 {
 305         int err;
 306         unsigned int header_size;
 307
 308         nf_bridge_update_protocol(skb);
 309         header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 310         err = skb_cow_head(skb, header_size);
 311         if (err)
 312                 return err;
 313
 314         skb_copy_to_linear_data_offset(skb, -header_size,
 315                                        skb->nf_bridge->data, header_size);
 316         __skb_push(skb, nf_bridge_encap_header_len(skb));
 317         return 0;
 318 }
 319
 320 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 321 /* Undo the changes made for ip6tables PREROUTING and continue the
 322  * bridge PRE_ROUTING hook. */
 323 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 324 {
 325         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 326         struct rtable *rt;
 327
 328         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 329                 skb->pkt_type = PACKET_OTHERHOST;
 330                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 331         }
 332         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 333
 334         rt = bridge_parent_rtable(nf_bridge->physindev);
 335         if (!rt) {
 336                 kfree_skb(skb);
 337                 return 0;
 338         }
 339         skb_dst_set_noref(skb, &rt->dst);
 340
 341         skb->dev = nf_bridge->physindev;
 342         nf_bridge_update_protocol(skb);
 343         nf_bridge_push_encap_header(skb);
 344         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 345                        br_handle_frame_finish, 1);
 346
 347         return 0;
 348 }
 349
 350 /* Obtain the correct destination MAC address, while preserving the original
 351  * source MAC address. If we already know this address, we just copy it. If we
 352  * don't, we use the neighbour framework to find out. In both cases, we make
 353  * sure that br_handle_frame_finish() is called afterwards.
 354  */
 355 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 356 {
 357         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 358         struct neighbour *neigh;
 359         struct dst_entry *dst;
 360
 361         skb->dev = bridge_parent(skb->dev);
 362         if (!skb->dev)
 363                 goto free_skb;
 364         dst = skb_dst(skb);
 365         neigh = dst_get_neighbour(dst);
 366         if (neigh->hh.hh_len) {
 367                 neigh_hh_bridge(&neigh->hh, skb);
 368                 skb->dev = nf_bridge->physindev;
 369                 return br_handle_frame_finish(skb);
 370         } else {
 371                 /* the neighbour function below overwrites the complete
 372                  * MAC header, so we save the Ethernet source address and
 373                  * protocol number. */
 374                 skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
 375                 /* tell br_dev_xmit to continue with forwarding */
 376                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 377                 return neigh->output(neigh, skb);
 378         }
 379 free_skb:
 380         kfree_skb(skb);
 381         return 0;
 382 }
 383
 384 /* This requires some explaining. If DNAT has taken place,
 385  * we will need to fix up the destination Ethernet address.
 386  *
 387  * There are two cases to consider:
 388  * 1. The packet was DNAT'ed to a device in the same bridge
 389  *    port group as it was received on. We can still bridge
 390  *    the packet.
 391  * 2. The packet was DNAT'ed to a different device, either
 392  *    a non-bridged device or another bridge port group.
 393  *    The packet will need to be routed.
 394  *
 395  * The correct way of distinguishing between these two cases is to
 396  * call ip_route_input() and to look at skb->dst->dev, which is
 397  * changed to the destination device if ip_route_input() succeeds.
 398  *
 399  * Let's first consider the case that ip_route_input() succeeds:
 400  *
 401  * If the output device equals the logical bridge device the packet
 402  * came in on, we can consider this bridging. The corresponding MAC
 403  * address will be obtained in br_nf_pre_routing_finish_bridge.
 404  * Otherwise, the packet is considered to be routed and we just
 405  * change the destination MAC address so that the packet will
 406  * later be passed up to the IP stack to be routed. For a redirected
 407  * packet, ip_route_input() will give back the localhost as output device,
 408  * which differs from the bridge device.
 409  *
 410  * Let's now consider the case that ip_route_input() fails:
 411  *
 412  * This can be because the destination address is martian, in which case
 413  * the packet will be dropped.
 414  * If IP forwarding is disabled, ip_route_input() will fail, while
 415  * ip_route_output_key() can return success. The source
 416  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 417  * thinks we're handling a locally generated packet and won't care
 418  * if IP forwarding is enabled. If the output device equals the logical bridge
 419  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 420  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 421  */
 422 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 423 {
 424         struct net_device *dev = skb->dev;
 425         struct iphdr *iph = ip_hdr(skb);
 426         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 427         struct rtable *rt;
 428         int err;
 429
 430         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 431                 skb->pkt_type = PACKET_OTHERHOST;
 432                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 433         }
 434         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 435         if (dnat_took_place(skb)) {
 436                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 437                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 438
 439                         /* If err equals -EHOSTUNREACH the error is due to a
 440                          * martian destination or due to the fact that
 441                          * forwarding is disabled. For most martian packets,
 442                          * ip_route_output_key() will fail. It won't fail for 2 types of
 443                          * martian destinations: loopback destinations and destination
 444                          * 0.0.0.0. In both cases the packet will be dropped because the
 445                          * destination is the loopback device and not the bridge. */
 446                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 447                                 goto free_skb;
 448
 449                         rt = ip_route_output(dev_net(dev), iph->daddr, 0,
 450                                              RT_TOS(iph->tos), 0);
 451                         if (!IS_ERR(rt)) {
 452                                 /* - Bridged-and-DNAT'ed traffic doesn't
 453                                  *   require ip_forwarding. */
 454                                 if (rt->dst.dev == dev) {
 455                                         skb_dst_set(skb, &rt->dst);
 456                                         goto bridged_dnat;
 457                                 }
 458                                 ip_rt_put(rt);
 459                         }
 460 free_skb:
 461                         kfree_skb(skb);
 462                         return 0;
 463                 } else {
 464                         if (skb_dst(skb)->dev == dev) {
 465 bridged_dnat:
 466                                 skb->dev = nf_bridge->physindev;
 467                                 nf_bridge_update_protocol(skb);
 468                                 nf_bridge_push_encap_header(skb);
 469                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 470                                                NF_BR_PRE_ROUTING,
 471                                                skb, skb->dev, NULL,
 472                                                br_nf_pre_routing_finish_bridge,
 473                                                1);
 474                                 return 0;
 475                         }
 476                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 477                         skb->pkt_type = PACKET_HOST;
 478                 }
 479         } else {
 480                 rt = bridge_parent_rtable(nf_bridge->physindev);
 481                 if (!rt) {
 482                         kfree_skb(skb);
 483                         return 0;
 484                 }
 485                 skb_dst_set_noref(skb, &rt->dst);
 486         }
 487
 488         skb->dev = nf_bridge->physindev;
 489         nf_bridge_update_protocol(skb);
 490         nf_bridge_push_encap_header(skb);
 491         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 492                        br_handle_frame_finish, 1);
 493
 494         return 0;
 495 }
 496
 497 /* Some common code for IPv4/IPv6 */
 498 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 499 {
 500         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 501
 502         if (skb->pkt_type == PACKET_OTHERHOST) {
 503                 skb->pkt_type = PACKET_HOST;
 504                 nf_bridge->mask |= BRNF_PKT_TYPE;
 505         }
 506
 507         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 508         nf_bridge->physindev = skb->dev;
 509         skb->dev = bridge_parent(skb->dev);
 510         if (skb->protocol == htons(ETH_P_8021Q))
 511                 nf_bridge->mask |= BRNF_8021Q;
 512         else if (skb->protocol == htons(ETH_P_PPP_SES))
 513                 nf_bridge->mask |= BRNF_PPPoE;
 514
 515         return skb->dev;
 516 }
 517
 518 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 519 static int check_hbh_len(struct sk_buff *skb)
 520 {
 521         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 522         u32 pkt_len;
 523         const unsigned char *nh = skb_network_header(skb);
 524         int off = raw - nh;
 525         int len = (raw[1] + 1) << 3;
 526
 527         if ((raw + len) - skb->data > skb_headlen(skb))
 528                 goto bad;
 529
 530         off += 2;
 531         len -= 2;
 532
 533         while (len > 0) {
 534                 int optlen = nh[off + 1] + 2;
 535
 536                 switch (nh[off]) {
 537                 case IPV6_TLV_PAD0:
 538                         optlen = 1;
 539                         break;
 540
 541                 case IPV6_TLV_PADN:
 542                         break;
 543
 544                 case IPV6_TLV_JUMBO:
 545                         if (nh[off + 1] != 4 || (off & 3) != 2)
 546                                 goto bad;
 547                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 548                         if (pkt_len <= IPV6_MAXPLEN ||
 549                             ipv6_hdr(skb)->payload_len)
 550                                 goto bad;
 551                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 552                                 goto bad;
 553                         if (pskb_trim_rcsum(skb,
 554                                             pkt_len + sizeof(struct ipv6hdr)))
 555                                 goto bad;
 556                         nh = skb_network_header(skb);
 557                         break;
 558                 default:
 559                         if (optlen > len)
 560                                 goto bad;
 561                         break;
 562                 }
 563                 off += optlen;
 564                 len -= optlen;
 565         }
 566         if (len == 0)
 567                 return 0;
 568 bad:
 569         return -1;
 570
 571 }
 572
 573 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 574  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 575 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 576                                            struct sk_buff *skb,
 577                                            const struct net_device *in,
 578                                            const struct net_device *out,
 579                                            int (*okfn)(struct sk_buff *))
 580 {
 581         const struct ipv6hdr *hdr;
 582         u32 pkt_len;
 583
 584         if (skb->len < sizeof(struct ipv6hdr))
 585                 return NF_DROP;
 586
 587         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 588                 return NF_DROP;
 589
 590         hdr = ipv6_hdr(skb);
 591
 592         if (hdr->version != 6)
 593                 return NF_DROP;
 594
 595         pkt_len = ntohs(hdr->payload_len);
 596
 597         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 598                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 599                         return NF_DROP;
 600                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 601                         return NF_DROP;
 602         }
 603         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 604                 return NF_DROP;
 605
 606         nf_bridge_put(skb->nf_bridge);
 607         if (!nf_bridge_alloc(skb))
 608                 return NF_DROP;
 609         if (!setup_pre_routing(skb))
 610                 return NF_DROP;
 611
 612         skb->protocol = htons(ETH_P_IPV6);
 613         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 614                 br_nf_pre_routing_finish_ipv6);
 615
 616         return NF_STOLEN;
 617 }
 618
 619 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 620  * Replicate the checks that IPv4 does on packet reception.
 621  * Set skb->dev to the bridge device (i.e. parent of the
 622  * receiving device) to make netfilter happy, the REDIRECT
 623  * target in particular.  Save the original destination IP
 624  * address to be able to detect DNAT afterwards. */
 625 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 626                                       const struct net_device *in,
 627                                       const struct net_device *out,
 628                                       int (*okfn)(struct sk_buff *))
 629 {
 630         struct net_bridge_port *p;
 631         struct net_bridge *br;
 632         __u32 len = nf_bridge_encap_header_len(skb);
 633
 634         if (unlikely(!pskb_may_pull(skb, len)))
 635                 return NF_DROP;
 636
 637         p = br_port_get_rcu(in);
 638         if (p == NULL)
 639                 return NF_DROP;
 640         br = p->br;
 641
 642         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 643             IS_PPPOE_IPV6(skb)) {
 644                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 645                         return NF_ACCEPT;
 646
 647                 nf_bridge_pull_encap_header_rcsum(skb);
 648                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 649         }
 650
 651         if (!brnf_call_iptables && !br->nf_call_iptables)
 652                 return NF_ACCEPT;
 653
 654         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 655             !IS_PPPOE_IP(skb))
 656                 return NF_ACCEPT;
 657
 658         nf_bridge_pull_encap_header_rcsum(skb);
 659
 660         if (br_parse_ip_options(skb))
 661                 return NF_DROP;
 662
 663         nf_bridge_put(skb->nf_bridge);
 664         if (!nf_bridge_alloc(skb))
 665                 return NF_DROP;
 666         if (!setup_pre_routing(skb))
 667                 return NF_DROP;
 668         store_orig_dstaddr(skb);
 669         skb->protocol = htons(ETH_P_IP);
 670
 671         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 672                 br_nf_pre_routing_finish);
 673
 674         return NF_STOLEN;
 675 }
 676
 677
 678 /* PF_BRIDGE/LOCAL_IN ************************************************/
 679 /* The packet is locally destined, which requires a real
 680  * dst_entry, so detach the fake one.  On the way up, the
 681  * packet would pass through PRE_ROUTING again (which already
 682  * took place when the packet entered the bridge), but we
 683  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 684  * prevent this from happening. */
 685 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 686                                    const struct net_device *in,
 687                                    const struct net_device *out,
 688                                    int (*okfn)(struct sk_buff *))
 689 {
 690         struct rtable *rt = skb_rtable(skb);
 691
 692         if (rt && rt == bridge_parent_rtable(in))
 693                 skb_dst_drop(skb);
 694
 695         return NF_ACCEPT;
 696 }
 697
 698 /* PF_BRIDGE/FORWARD *************************************************/
 699 static int br_nf_forward_finish(struct sk_buff *skb)
 700 {
 701         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 702         struct net_device *in;
 703
 704         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 705                 in = nf_bridge->physindev;
 706                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 707                         skb->pkt_type = PACKET_OTHERHOST;
 708                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 709                 }
 710                 nf_bridge_update_protocol(skb);
 711         } else {
 712                 in = *((struct net_device **)(skb->cb));
 713         }
 714         nf_bridge_push_encap_header(skb);
 715
 716         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 717                        skb->dev, br_forward_finish, 1);
 718         return 0;
 719 }
 720
 721 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 722  * netfilter with indev and outdev set to the bridge device,
 723  * but we are still able to filter on the 'real' indev/outdev
 724  * because of the physdev module. For ARP, indev and outdev are the
 725  * bridge ports. */
 726 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 727                                      const struct net_device *in,
 728                                      const struct net_device *out,
 729                                      int (*okfn)(struct sk_buff *))
 730 {
 731         struct nf_bridge_info *nf_bridge;
 732         struct net_device *parent;
 733         u_int8_t pf;
 734
 735         if (!skb->nf_bridge)
 736                 return NF_ACCEPT;
 737
 738         /* Need exclusive nf_bridge_info since we might have multiple
 739          * different physoutdevs. */
 740         if (!nf_bridge_unshare(skb))
 741                 return NF_DROP;
 742
 743         parent = bridge_parent(out);
 744         if (!parent)
 745                 return NF_DROP;
 746
 747         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 748             IS_PPPOE_IP(skb))
 749                 pf = PF_INET;
 750         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 751                  IS_PPPOE_IPV6(skb))
 752                 pf = PF_INET6;
 753         else
 754                 return NF_ACCEPT;
 755
 756         nf_bridge_pull_encap_header(skb);
 757
 758         nf_bridge = skb->nf_bridge;
 759         if (skb->pkt_type == PACKET_OTHERHOST) {
 760                 skb->pkt_type = PACKET_HOST;
 761                 nf_bridge->mask |= BRNF_PKT_TYPE;
 762         }
 763
 764         if (pf == PF_INET && br_parse_ip_options(skb))
 765                 return NF_DROP;
 766
 767         /* The physdev module checks on this */
 768         nf_bridge->mask |= BRNF_BRIDGED;
 769         nf_bridge->physoutdev = skb->dev;
 770         if (pf == PF_INET)
 771                 skb->protocol = htons(ETH_P_IP);
 772         else
 773                 skb->protocol = htons(ETH_P_IPV6);
 774
 775         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 776                 br_nf_forward_finish);
 777
 778         return NF_STOLEN;
 779 }
 780
 781 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 782                                       const struct net_device *in,
 783                                       const struct net_device *out,
 784                                       int (*okfn)(struct sk_buff *))
 785 {
 786         struct net_bridge_port *p;
 787         struct net_bridge *br;
 788         struct net_device **d = (struct net_device **)(skb->cb);
 789
 790         p = br_port_get_rcu(out);
 791         if (p == NULL)
 792                 return NF_ACCEPT;
 793         br = p->br;
 794
 795         if (!brnf_call_arptables && !br->nf_call_arptables)
 796                 return NF_ACCEPT;
 797
 798         if (skb->protocol != htons(ETH_P_ARP)) {
 799                 if (!IS_VLAN_ARP(skb))
 800                         return NF_ACCEPT;
 801                 nf_bridge_pull_encap_header(skb);
 802         }
 803
 804         if (arp_hdr(skb)->ar_pln != 4) {
 805                 if (IS_VLAN_ARP(skb))
 806                         nf_bridge_push_encap_header(skb);
 807                 return NF_ACCEPT;
 808         }
 809         *d = (struct net_device *)in;
 810         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 811                 (struct net_device *)out, br_nf_forward_finish);
 812
 813         return NF_STOLEN;
 814 }
 815
 816 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 817 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 818 {
 819         int ret;
 820
 821         if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
 822             skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
 823             !skb_is_gso(skb)) {
 824                 if (br_parse_ip_options(skb))
 825                         /* Drop invalid packet */
 826                         return NF_DROP;
 827                 ret = ip_fragment(skb, br_dev_queue_push_xmit);
 828         } else
 829                 ret = br_dev_queue_push_xmit(skb);
 830
 831         return ret;
 832 }
 833 #else
 834 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 835 {
 836         return br_dev_queue_push_xmit(skb);
 837 }
 838 #endif
 839
 840 /* PF_BRIDGE/POST_ROUTING ********************************************/
 841 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 842                                        const struct net_device *in,
 843                                        const struct net_device *out,
 844                                        int (*okfn)(struct sk_buff *))
 845 {
 846         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 847         struct net_device *realoutdev = bridge_parent(skb->dev);
 848         u_int8_t pf;
 849
 850         if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 851                 return NF_ACCEPT;
 852
 853         if (!realoutdev)
 854                 return NF_DROP;
 855
 856         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 857             IS_PPPOE_IP(skb))
 858                 pf = PF_INET;
 859         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 860                  IS_PPPOE_IPV6(skb))
 861                 pf = PF_INET6;
 862         else
 863                 return NF_ACCEPT;
 864
 865         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 866          * about the value of skb->pkt_type. */
 867         if (skb->pkt_type == PACKET_OTHERHOST) {
 868                 skb->pkt_type = PACKET_HOST;
 869                 nf_bridge->mask |= BRNF_PKT_TYPE;
 870         }
 871
 872         nf_bridge_pull_encap_header(skb);
 873         nf_bridge_save_header(skb);
 874         if (pf == PF_INET)
 875                 skb->protocol = htons(ETH_P_IP);
 876         else
 877                 skb->protocol = htons(ETH_P_IPV6);
 878
 879         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 880                 br_nf_dev_queue_xmit);
 881
 882         return NF_STOLEN;
 883 }
 884
 885 /* IP/SABOTAGE *****************************************************/
 886 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 887  * for the second time. */
 888 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 889                                    const struct net_device *in,
 890                                    const struct net_device *out,
 891                                    int (*okfn)(struct sk_buff *))
 892 {
 893         if (skb->nf_bridge &&
 894             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 895                 return NF_STOP;
 896         }
 897
 898         return NF_ACCEPT;
 899 }
 900
 901 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 902  * br_dev_queue_push_xmit is called afterwards */
 903 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 904         {
 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         },
 911         {
 912                 .hook = br_nf_local_in,
 913                 .owner = THIS_MODULE,
 914                 .pf = PF_BRIDGE,
 915                 .hooknum = NF_BR_LOCAL_IN,
 916                 .priority = NF_BR_PRI_BRNF,
 917         },
 918         {
 919                 .hook = br_nf_forward_ip,
 920                 .owner = THIS_MODULE,
 921                 .pf = PF_BRIDGE,
 922                 .hooknum = NF_BR_FORWARD,
 923                 .priority = NF_BR_PRI_BRNF - 1,
 924         },
 925         {
 926                 .hook = br_nf_forward_arp,
 927                 .owner = THIS_MODULE,
 928                 .pf = PF_BRIDGE,
 929                 .hooknum = NF_BR_FORWARD,
 930                 .priority = NF_BR_PRI_BRNF,
 931         },
 932         {
 933                 .hook = br_nf_post_routing,
 934                 .owner = THIS_MODULE,
 935                 .pf = PF_BRIDGE,
 936                 .hooknum = NF_BR_POST_ROUTING,
 937                 .priority = NF_BR_PRI_LAST,
 938         },
 939         {
 940                 .hook = ip_sabotage_in,
 941                 .owner = THIS_MODULE,
 942                 .pf = PF_INET,
 943                 .hooknum = NF_INET_PRE_ROUTING,
 944                 .priority = NF_IP_PRI_FIRST,
 945         },
 946         {
 947                 .hook = ip_sabotage_in,
 948                 .owner = THIS_MODULE,
 949                 .pf = PF_INET6,
 950                 .hooknum = NF_INET_PRE_ROUTING,
 951                 .priority = NF_IP6_PRI_FIRST,
 952         },
 953 };
 954
 955 #ifdef CONFIG_SYSCTL
 956 static
 957 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 958                             void __user * buffer, size_t * lenp, loff_t * ppos)
 959 {
 960         int ret;
 961
 962         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 963
 964         if (write && *(int *)(ctl->data))
 965                 *(int *)(ctl->data) = 1;
 966         return ret;
 967 }
 968
 969 static ctl_table brnf_table[] = {
 970         {
 971                 .procname       = "bridge-nf-call-arptables",
 972                 .data           = &brnf_call_arptables,
 973                 .maxlen         = sizeof(int),
 974                 .mode           = 0644,
 975                 .proc_handler   = brnf_sysctl_call_tables,
 976         },
 977         {
 978                 .procname       = "bridge-nf-call-iptables",
 979                 .data           = &brnf_call_iptables,
 980                 .maxlen         = sizeof(int),
 981                 .mode           = 0644,
 982                 .proc_handler   = brnf_sysctl_call_tables,
 983         },
 984         {
 985                 .procname       = "bridge-nf-call-ip6tables",
 986                 .data           = &brnf_call_ip6tables,
 987                 .maxlen         = sizeof(int),
 988                 .mode           = 0644,
 989                 .proc_handler   = brnf_sysctl_call_tables,
 990         },
 991         {
 992                 .procname       = "bridge-nf-filter-vlan-tagged",
 993                 .data           = &brnf_filter_vlan_tagged,
 994                 .maxlen         = sizeof(int),
 995                 .mode           = 0644,
 996                 .proc_handler   = brnf_sysctl_call_tables,
 997         },
 998         {
 999                 .procname       = "bridge-nf-filter-pppoe-tagged",
1000                 .data           = &brnf_filter_pppoe_tagged,
1001                 .maxlen         = sizeof(int),
1002                 .mode           = 0644,
1003                 .proc_handler   = brnf_sysctl_call_tables,
1004         },
1005         { }
1006 };
1007
1008 static struct ctl_path brnf_path[] = {
1009         { .procname = "net", },
1010         { .procname = "bridge", },
1011         { }
1012 };
1013 #endif
1014
1015 int __init br_netfilter_init(void)
1016 {
1017         int ret;
1018
1019         ret = dst_entries_init(&fake_dst_ops);
1020         if (ret < 0)
1021                 return ret;
1022
1023         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1024         if (ret < 0) {
1025                 dst_entries_destroy(&fake_dst_ops);
1026                 return ret;
1027         }
1028 #ifdef CONFIG_SYSCTL
1029         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1030         if (brnf_sysctl_header == NULL) {
1031                 printk(KERN_WARNING
1032                        "br_netfilter: can't register to sysctl.\n");
1033                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1034                 dst_entries_destroy(&fake_dst_ops);
1035                 return -ENOMEM;
1036         }
1037 #endif
1038         printk(KERN_NOTICE "Bridge firewalling registered\n");
1039         return 0;
1040 }
1041
1042 void br_netfilter_fini(void)
1043 {
1044         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1045 #ifdef CONFIG_SYSCTL
1046         unregister_sysctl_table(brnf_sysctl_header);
1047 #endif
1048         dst_entries_destroy(&fake_dst_ops);
1049 }