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 struct dst_ops fake_dst_ops = {
 118         .family =               AF_INET,
 119         .protocol =             cpu_to_be16(ETH_P_IP),
 120         .update_pmtu =          fake_update_pmtu,
 121         .cow_metrics =          fake_cow_metrics,
 122         .neigh_lookup =         fake_neigh_lookup,
 123 };
 124
 125 /*
 126  * Initialize bogus route table used to keep netfilter happy.
 127  * Currently, we fill in the PMTU entry because netfilter
 128  * refragmentation needs it, and the rt_flags entry because
 129  * ipt_REJECT needs it.  Future netfilter modules might
 130  * require us to fill additional fields.
 131  */
 132 static const u32 br_dst_default_metrics[RTAX_MAX] = {
 133         [RTAX_MTU - 1] = 1500,
 134 };
 135
 136 void br_netfilter_rtable_init(struct net_bridge *br)
 137 {
 138         struct rtable *rt = &br->fake_rtable;
 139
 140         atomic_set(&rt->dst.__refcnt, 1);
 141         rt->dst.dev = br->dev;
 142         rt->dst.path = &rt->dst;
 143         dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
 144         rt->dst.flags   = DST_NOXFRM;
 145         rt->dst.ops = &fake_dst_ops;
 146 }
 147
 148 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 149 {
 150         struct net_bridge_port *port;
 151
 152         port = br_port_get_rcu(dev);
 153         return port ? &port->br->fake_rtable : NULL;
 154 }
 155
 156 static inline struct net_device *bridge_parent(const struct net_device *dev)
 157 {
 158         struct net_bridge_port *port;
 159
 160         port = br_port_get_rcu(dev);
 161         return port ? port->br->dev : NULL;
 162 }
 163
 164 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 165 {
 166         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 167         if (likely(skb->nf_bridge))
 168                 atomic_set(&(skb->nf_bridge->use), 1);
 169
 170         return skb->nf_bridge;
 171 }
 172
 173 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 174 {
 175         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 176
 177         if (atomic_read(&nf_bridge->use) > 1) {
 178                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 179
 180                 if (tmp) {
 181                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 182                         atomic_set(&tmp->use, 1);
 183                 }
 184                 nf_bridge_put(nf_bridge);
 185                 nf_bridge = tmp;
 186         }
 187         return nf_bridge;
 188 }
 189
 190 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 191 {
 192         unsigned int len = nf_bridge_encap_header_len(skb);
 193
 194         skb_push(skb, len);
 195         skb->network_header -= len;
 196 }
 197
 198 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 199 {
 200         unsigned int len = nf_bridge_encap_header_len(skb);
 201
 202         skb_pull(skb, len);
 203         skb->network_header += len;
 204 }
 205
 206 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 207 {
 208         unsigned int len = nf_bridge_encap_header_len(skb);
 209
 210         skb_pull_rcsum(skb, len);
 211         skb->network_header += len;
 212 }
 213
 214 static inline void nf_bridge_save_header(struct sk_buff *skb)
 215 {
 216         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 217
 218         skb_copy_from_linear_data_offset(skb, -header_size,
 219                                          skb->nf_bridge->data, header_size);
 220 }
 221
 222 static inline void nf_bridge_update_protocol(struct sk_buff *skb)
 223 {
 224         if (skb->nf_bridge->mask & BRNF_8021Q)
 225                 skb->protocol = htons(ETH_P_8021Q);
 226         else if (skb->nf_bridge->mask & BRNF_PPPoE)
 227                 skb->protocol = htons(ETH_P_PPP_SES);
 228 }
 229
 230 /* When handing a packet over to the IP layer
 231  * check whether we have a skb that is in the
 232  * expected format
 233  */
 234
 235 static int br_parse_ip_options(struct sk_buff *skb)
 236 {
 237         struct ip_options *opt;
 238         const struct iphdr *iph;
 239         struct net_device *dev = skb->dev;
 240         u32 len;
 241
 242         iph = ip_hdr(skb);
 243         opt = &(IPCB(skb)->opt);
 244
 245         /* Basic sanity checks */
 246         if (iph->ihl < 5 || iph->version != 4)
 247                 goto inhdr_error;
 248
 249         if (!pskb_may_pull(skb, iph->ihl*4))
 250                 goto inhdr_error;
 251
 252         iph = ip_hdr(skb);
 253         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 254                 goto inhdr_error;
 255
 256         len = ntohs(iph->tot_len);
 257         if (skb->len < len) {
 258                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 259                 goto drop;
 260         } else if (len < (iph->ihl*4))
 261                 goto inhdr_error;
 262
 263         if (pskb_trim_rcsum(skb, len)) {
 264                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 265                 goto drop;
 266         }
 267
 268         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 269         if (iph->ihl == 5)
 270                 return 0;
 271
 272         opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 273         if (ip_options_compile(dev_net(dev), opt, skb))
 274                 goto inhdr_error;
 275
 276         /* Check correct handling of SRR option */
 277         if (unlikely(opt->srr)) {
 278                 struct in_device *in_dev = __in_dev_get_rcu(dev);
 279                 if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
 280                         goto drop;
 281
 282                 if (ip_options_rcv_srr(skb))
 283                         goto drop;
 284         }
 285
 286         return 0;
 287
 288 inhdr_error:
 289         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 290 drop:
 291         return -1;
 292 }
 293
 294 /* Fill in the header for fragmented IP packets handled by
 295  * the IPv4 connection tracking code.
 296  */
 297 int nf_bridge_copy_header(struct sk_buff *skb)
 298 {
 299         int err;
 300         unsigned int header_size;
 301
 302         nf_bridge_update_protocol(skb);
 303         header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 304         err = skb_cow_head(skb, header_size);
 305         if (err)
 306                 return err;
 307
 308         skb_copy_to_linear_data_offset(skb, -header_size,
 309                                        skb->nf_bridge->data, header_size);
 310         __skb_push(skb, nf_bridge_encap_header_len(skb));
 311         return 0;
 312 }
 313
 314 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 315 /* Undo the changes made for ip6tables PREROUTING and continue the
 316  * bridge PRE_ROUTING hook. */
 317 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 318 {
 319         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 320         struct rtable *rt;
 321
 322         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 323                 skb->pkt_type = PACKET_OTHERHOST;
 324                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 325         }
 326         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 327
 328         rt = bridge_parent_rtable(nf_bridge->physindev);
 329         if (!rt) {
 330                 kfree_skb(skb);
 331                 return 0;
 332         }
 333         skb_dst_set_noref(skb, &rt->dst);
 334
 335         skb->dev = nf_bridge->physindev;
 336         nf_bridge_update_protocol(skb);
 337         nf_bridge_push_encap_header(skb);
 338         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 339                        br_handle_frame_finish, 1);
 340
 341         return 0;
 342 }
 343
 344 /* Obtain the correct destination MAC address, while preserving the original
 345  * source MAC address. If we already know this address, we just copy it. If we
 346  * don't, we use the neighbour framework to find out. In both cases, we make
 347  * sure that br_handle_frame_finish() is called afterwards.
 348  */
 349 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 350 {
 351         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 352         struct neighbour *neigh;
 353         struct dst_entry *dst;
 354
 355         skb->dev = bridge_parent(skb->dev);
 356         if (!skb->dev)
 357                 goto free_skb;
 358         dst = skb_dst(skb);
 359         neigh = dst_get_neighbour(dst);
 360         if (neigh->hh.hh_len) {
 361                 neigh_hh_bridge(&neigh->hh, skb);
 362                 skb->dev = nf_bridge->physindev;
 363                 return br_handle_frame_finish(skb);
 364         } else {
 365                 /* the neighbour function below overwrites the complete
 366                  * MAC header, so we save the Ethernet source address and
 367                  * protocol number. */
 368                 skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
 369                 /* tell br_dev_xmit to continue with forwarding */
 370                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 371                 return neigh->output(neigh, skb);
 372         }
 373 free_skb:
 374         kfree_skb(skb);
 375         return 0;
 376 }
 377
 378 /* This requires some explaining. If DNAT has taken place,
 379  * we will need to fix up the destination Ethernet address.
 380  *
 381  * There are two cases to consider:
 382  * 1. The packet was DNAT'ed to a device in the same bridge
 383  *    port group as it was received on. We can still bridge
 384  *    the packet.
 385  * 2. The packet was DNAT'ed to a different device, either
 386  *    a non-bridged device or another bridge port group.
 387  *    The packet will need to be routed.
 388  *
 389  * The correct way of distinguishing between these two cases is to
 390  * call ip_route_input() and to look at skb->dst->dev, which is
 391  * changed to the destination device if ip_route_input() succeeds.
 392  *
 393  * Let's first consider the case that ip_route_input() succeeds:
 394  *
 395  * If the output device equals the logical bridge device the packet
 396  * came in on, we can consider this bridging. The corresponding MAC
 397  * address will be obtained in br_nf_pre_routing_finish_bridge.
 398  * Otherwise, the packet is considered to be routed and we just
 399  * change the destination MAC address so that the packet will
 400  * later be passed up to the IP stack to be routed. For a redirected
 401  * packet, ip_route_input() will give back the localhost as output device,
 402  * which differs from the bridge device.
 403  *
 404  * Let's now consider the case that ip_route_input() fails:
 405  *
 406  * This can be because the destination address is martian, in which case
 407  * the packet will be dropped.
 408  * If IP forwarding is disabled, ip_route_input() will fail, while
 409  * ip_route_output_key() can return success. The source
 410  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 411  * thinks we're handling a locally generated packet and won't care
 412  * if IP forwarding is enabled. If the output device equals the logical bridge
 413  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 414  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 415  */
 416 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 417 {
 418         struct net_device *dev = skb->dev;
 419         struct iphdr *iph = ip_hdr(skb);
 420         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 421         struct rtable *rt;
 422         int err;
 423
 424         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 425                 skb->pkt_type = PACKET_OTHERHOST;
 426                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 427         }
 428         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 429         if (dnat_took_place(skb)) {
 430                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 431                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 432
 433                         /* If err equals -EHOSTUNREACH the error is due to a
 434                          * martian destination or due to the fact that
 435                          * forwarding is disabled. For most martian packets,
 436                          * ip_route_output_key() will fail. It won't fail for 2 types of
 437                          * martian destinations: loopback destinations and destination
 438                          * 0.0.0.0. In both cases the packet will be dropped because the
 439                          * destination is the loopback device and not the bridge. */
 440                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 441                                 goto free_skb;
 442
 443                         rt = ip_route_output(dev_net(dev), iph->daddr, 0,
 444                                              RT_TOS(iph->tos), 0);
 445                         if (!IS_ERR(rt)) {
 446                                 /* - Bridged-and-DNAT'ed traffic doesn't
 447                                  *   require ip_forwarding. */
 448                                 if (rt->dst.dev == dev) {
 449                                         skb_dst_set(skb, &rt->dst);
 450                                         goto bridged_dnat;
 451                                 }
 452                                 ip_rt_put(rt);
 453                         }
 454 free_skb:
 455                         kfree_skb(skb);
 456                         return 0;
 457                 } else {
 458                         if (skb_dst(skb)->dev == dev) {
 459 bridged_dnat:
 460                                 skb->dev = nf_bridge->physindev;
 461                                 nf_bridge_update_protocol(skb);
 462                                 nf_bridge_push_encap_header(skb);
 463                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 464                                                NF_BR_PRE_ROUTING,
 465                                                skb, skb->dev, NULL,
 466                                                br_nf_pre_routing_finish_bridge,
 467                                                1);
 468                                 return 0;
 469                         }
 470                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 471                         skb->pkt_type = PACKET_HOST;
 472                 }
 473         } else {
 474                 rt = bridge_parent_rtable(nf_bridge->physindev);
 475                 if (!rt) {
 476                         kfree_skb(skb);
 477                         return 0;
 478                 }
 479                 skb_dst_set_noref(skb, &rt->dst);
 480         }
 481
 482         skb->dev = nf_bridge->physindev;
 483         nf_bridge_update_protocol(skb);
 484         nf_bridge_push_encap_header(skb);
 485         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 486                        br_handle_frame_finish, 1);
 487
 488         return 0;
 489 }
 490
 491 /* Some common code for IPv4/IPv6 */
 492 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 493 {
 494         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 495
 496         if (skb->pkt_type == PACKET_OTHERHOST) {
 497                 skb->pkt_type = PACKET_HOST;
 498                 nf_bridge->mask |= BRNF_PKT_TYPE;
 499         }
 500
 501         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 502         nf_bridge->physindev = skb->dev;
 503         skb->dev = bridge_parent(skb->dev);
 504         if (skb->protocol == htons(ETH_P_8021Q))
 505                 nf_bridge->mask |= BRNF_8021Q;
 506         else if (skb->protocol == htons(ETH_P_PPP_SES))
 507                 nf_bridge->mask |= BRNF_PPPoE;
 508
 509         return skb->dev;
 510 }
 511
 512 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 513 static int check_hbh_len(struct sk_buff *skb)
 514 {
 515         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 516         u32 pkt_len;
 517         const unsigned char *nh = skb_network_header(skb);
 518         int off = raw - nh;
 519         int len = (raw[1] + 1) << 3;
 520
 521         if ((raw + len) - skb->data > skb_headlen(skb))
 522                 goto bad;
 523
 524         off += 2;
 525         len -= 2;
 526
 527         while (len > 0) {
 528                 int optlen = nh[off + 1] + 2;
 529
 530                 switch (nh[off]) {
 531                 case IPV6_TLV_PAD0:
 532                         optlen = 1;
 533                         break;
 534
 535                 case IPV6_TLV_PADN:
 536                         break;
 537
 538                 case IPV6_TLV_JUMBO:
 539                         if (nh[off + 1] != 4 || (off & 3) != 2)
 540                                 goto bad;
 541                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 542                         if (pkt_len <= IPV6_MAXPLEN ||
 543                             ipv6_hdr(skb)->payload_len)
 544                                 goto bad;
 545                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 546                                 goto bad;
 547                         if (pskb_trim_rcsum(skb,
 548                                             pkt_len + sizeof(struct ipv6hdr)))
 549                                 goto bad;
 550                         nh = skb_network_header(skb);
 551                         break;
 552                 default:
 553                         if (optlen > len)
 554                                 goto bad;
 555                         break;
 556                 }
 557                 off += optlen;
 558                 len -= optlen;
 559         }
 560         if (len == 0)
 561                 return 0;
 562 bad:
 563         return -1;
 564
 565 }
 566
 567 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 568  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 569 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 570                                            struct sk_buff *skb,
 571                                            const struct net_device *in,
 572                                            const struct net_device *out,
 573                                            int (*okfn)(struct sk_buff *))
 574 {
 575         const struct ipv6hdr *hdr;
 576         u32 pkt_len;
 577
 578         if (skb->len < sizeof(struct ipv6hdr))
 579                 return NF_DROP;
 580
 581         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 582                 return NF_DROP;
 583
 584         hdr = ipv6_hdr(skb);
 585
 586         if (hdr->version != 6)
 587                 return NF_DROP;
 588
 589         pkt_len = ntohs(hdr->payload_len);
 590
 591         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 592                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 593                         return NF_DROP;
 594                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 595                         return NF_DROP;
 596         }
 597         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 598                 return NF_DROP;
 599
 600         nf_bridge_put(skb->nf_bridge);
 601         if (!nf_bridge_alloc(skb))
 602                 return NF_DROP;
 603         if (!setup_pre_routing(skb))
 604                 return NF_DROP;
 605
 606         skb->protocol = htons(ETH_P_IPV6);
 607         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 608                 br_nf_pre_routing_finish_ipv6);
 609
 610         return NF_STOLEN;
 611 }
 612
 613 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 614  * Replicate the checks that IPv4 does on packet reception.
 615  * Set skb->dev to the bridge device (i.e. parent of the
 616  * receiving device) to make netfilter happy, the REDIRECT
 617  * target in particular.  Save the original destination IP
 618  * address to be able to detect DNAT afterwards. */
 619 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 620                                       const struct net_device *in,
 621                                       const struct net_device *out,
 622                                       int (*okfn)(struct sk_buff *))
 623 {
 624         struct net_bridge_port *p;
 625         struct net_bridge *br;
 626         __u32 len = nf_bridge_encap_header_len(skb);
 627
 628         if (unlikely(!pskb_may_pull(skb, len)))
 629                 return NF_DROP;
 630
 631         p = br_port_get_rcu(in);
 632         if (p == NULL)
 633                 return NF_DROP;
 634         br = p->br;
 635
 636         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 637             IS_PPPOE_IPV6(skb)) {
 638                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 639                         return NF_ACCEPT;
 640
 641                 nf_bridge_pull_encap_header_rcsum(skb);
 642                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 643         }
 644
 645         if (!brnf_call_iptables && !br->nf_call_iptables)
 646                 return NF_ACCEPT;
 647
 648         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 649             !IS_PPPOE_IP(skb))
 650                 return NF_ACCEPT;
 651
 652         nf_bridge_pull_encap_header_rcsum(skb);
 653
 654         if (br_parse_ip_options(skb))
 655                 return NF_DROP;
 656
 657         nf_bridge_put(skb->nf_bridge);
 658         if (!nf_bridge_alloc(skb))
 659                 return NF_DROP;
 660         if (!setup_pre_routing(skb))
 661                 return NF_DROP;
 662         store_orig_dstaddr(skb);
 663         skb->protocol = htons(ETH_P_IP);
 664
 665         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 666                 br_nf_pre_routing_finish);
 667
 668         return NF_STOLEN;
 669 }
 670
 671
 672 /* PF_BRIDGE/LOCAL_IN ************************************************/
 673 /* The packet is locally destined, which requires a real
 674  * dst_entry, so detach the fake one.  On the way up, the
 675  * packet would pass through PRE_ROUTING again (which already
 676  * took place when the packet entered the bridge), but we
 677  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 678  * prevent this from happening. */
 679 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 680                                    const struct net_device *in,
 681                                    const struct net_device *out,
 682                                    int (*okfn)(struct sk_buff *))
 683 {
 684         struct rtable *rt = skb_rtable(skb);
 685
 686         if (rt && rt == bridge_parent_rtable(in))
 687                 skb_dst_drop(skb);
 688
 689         return NF_ACCEPT;
 690 }
 691
 692 /* PF_BRIDGE/FORWARD *************************************************/
 693 static int br_nf_forward_finish(struct sk_buff *skb)
 694 {
 695         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 696         struct net_device *in;
 697
 698         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 699                 in = nf_bridge->physindev;
 700                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 701                         skb->pkt_type = PACKET_OTHERHOST;
 702                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 703                 }
 704                 nf_bridge_update_protocol(skb);
 705         } else {
 706                 in = *((struct net_device **)(skb->cb));
 707         }
 708         nf_bridge_push_encap_header(skb);
 709
 710         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 711                        skb->dev, br_forward_finish, 1);
 712         return 0;
 713 }
 714
 715 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 716  * netfilter with indev and outdev set to the bridge device,
 717  * but we are still able to filter on the 'real' indev/outdev
 718  * because of the physdev module. For ARP, indev and outdev are the
 719  * bridge ports. */
 720 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 721                                      const struct net_device *in,
 722                                      const struct net_device *out,
 723                                      int (*okfn)(struct sk_buff *))
 724 {
 725         struct nf_bridge_info *nf_bridge;
 726         struct net_device *parent;
 727         u_int8_t pf;
 728
 729         if (!skb->nf_bridge)
 730                 return NF_ACCEPT;
 731
 732         /* Need exclusive nf_bridge_info since we might have multiple
 733          * different physoutdevs. */
 734         if (!nf_bridge_unshare(skb))
 735                 return NF_DROP;
 736
 737         parent = bridge_parent(out);
 738         if (!parent)
 739                 return NF_DROP;
 740
 741         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 742             IS_PPPOE_IP(skb))
 743                 pf = PF_INET;
 744         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 745                  IS_PPPOE_IPV6(skb))
 746                 pf = PF_INET6;
 747         else
 748                 return NF_ACCEPT;
 749
 750         nf_bridge_pull_encap_header(skb);
 751
 752         nf_bridge = skb->nf_bridge;
 753         if (skb->pkt_type == PACKET_OTHERHOST) {
 754                 skb->pkt_type = PACKET_HOST;
 755                 nf_bridge->mask |= BRNF_PKT_TYPE;
 756         }
 757
 758         if (pf == PF_INET && br_parse_ip_options(skb))
 759                 return NF_DROP;
 760
 761         /* The physdev module checks on this */
 762         nf_bridge->mask |= BRNF_BRIDGED;
 763         nf_bridge->physoutdev = skb->dev;
 764         if (pf == PF_INET)
 765                 skb->protocol = htons(ETH_P_IP);
 766         else
 767                 skb->protocol = htons(ETH_P_IPV6);
 768
 769         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 770                 br_nf_forward_finish);
 771
 772         return NF_STOLEN;
 773 }
 774
 775 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 776                                       const struct net_device *in,
 777                                       const struct net_device *out,
 778                                       int (*okfn)(struct sk_buff *))
 779 {
 780         struct net_bridge_port *p;
 781         struct net_bridge *br;
 782         struct net_device **d = (struct net_device **)(skb->cb);
 783
 784         p = br_port_get_rcu(out);
 785         if (p == NULL)
 786                 return NF_ACCEPT;
 787         br = p->br;
 788
 789         if (!brnf_call_arptables && !br->nf_call_arptables)
 790                 return NF_ACCEPT;
 791
 792         if (skb->protocol != htons(ETH_P_ARP)) {
 793                 if (!IS_VLAN_ARP(skb))
 794                         return NF_ACCEPT;
 795                 nf_bridge_pull_encap_header(skb);
 796         }
 797
 798         if (arp_hdr(skb)->ar_pln != 4) {
 799                 if (IS_VLAN_ARP(skb))
 800                         nf_bridge_push_encap_header(skb);
 801                 return NF_ACCEPT;
 802         }
 803         *d = (struct net_device *)in;
 804         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 805                 (struct net_device *)out, br_nf_forward_finish);
 806
 807         return NF_STOLEN;
 808 }
 809
 810 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 811 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 812 {
 813         int ret;
 814
 815         if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
 816             skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
 817             !skb_is_gso(skb)) {
 818                 if (br_parse_ip_options(skb))
 819                         /* Drop invalid packet */
 820                         return NF_DROP;
 821                 ret = ip_fragment(skb, br_dev_queue_push_xmit);
 822         } else
 823                 ret = br_dev_queue_push_xmit(skb);
 824
 825         return ret;
 826 }
 827 #else
 828 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 829 {
 830         return br_dev_queue_push_xmit(skb);
 831 }
 832 #endif
 833
 834 /* PF_BRIDGE/POST_ROUTING ********************************************/
 835 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 836                                        const struct net_device *in,
 837                                        const struct net_device *out,
 838                                        int (*okfn)(struct sk_buff *))
 839 {
 840         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 841         struct net_device *realoutdev = bridge_parent(skb->dev);
 842         u_int8_t pf;
 843
 844         if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 845                 return NF_ACCEPT;
 846
 847         if (!realoutdev)
 848                 return NF_DROP;
 849
 850         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 851             IS_PPPOE_IP(skb))
 852                 pf = PF_INET;
 853         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 854                  IS_PPPOE_IPV6(skb))
 855                 pf = PF_INET6;
 856         else
 857                 return NF_ACCEPT;
 858
 859         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 860          * about the value of skb->pkt_type. */
 861         if (skb->pkt_type == PACKET_OTHERHOST) {
 862                 skb->pkt_type = PACKET_HOST;
 863                 nf_bridge->mask |= BRNF_PKT_TYPE;
 864         }
 865
 866         nf_bridge_pull_encap_header(skb);
 867         nf_bridge_save_header(skb);
 868         if (pf == PF_INET)
 869                 skb->protocol = htons(ETH_P_IP);
 870         else
 871                 skb->protocol = htons(ETH_P_IPV6);
 872
 873         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 874                 br_nf_dev_queue_xmit);
 875
 876         return NF_STOLEN;
 877 }
 878
 879 /* IP/SABOTAGE *****************************************************/
 880 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 881  * for the second time. */
 882 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 883                                    const struct net_device *in,
 884                                    const struct net_device *out,
 885                                    int (*okfn)(struct sk_buff *))
 886 {
 887         if (skb->nf_bridge &&
 888             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 889                 return NF_STOP;
 890         }
 891
 892         return NF_ACCEPT;
 893 }
 894
 895 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 896  * br_dev_queue_push_xmit is called afterwards */
 897 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 898         {
 899                 .hook = br_nf_pre_routing,
 900                 .owner = THIS_MODULE,
 901                 .pf = PF_BRIDGE,
 902                 .hooknum = NF_BR_PRE_ROUTING,
 903                 .priority = NF_BR_PRI_BRNF,
 904         },
 905         {
 906                 .hook = br_nf_local_in,
 907                 .owner = THIS_MODULE,
 908                 .pf = PF_BRIDGE,
 909                 .hooknum = NF_BR_LOCAL_IN,
 910                 .priority = NF_BR_PRI_BRNF,
 911         },
 912         {
 913                 .hook = br_nf_forward_ip,
 914                 .owner = THIS_MODULE,
 915                 .pf = PF_BRIDGE,
 916                 .hooknum = NF_BR_FORWARD,
 917                 .priority = NF_BR_PRI_BRNF - 1,
 918         },
 919         {
 920                 .hook = br_nf_forward_arp,
 921                 .owner = THIS_MODULE,
 922                 .pf = PF_BRIDGE,
 923                 .hooknum = NF_BR_FORWARD,
 924                 .priority = NF_BR_PRI_BRNF,
 925         },
 926         {
 927                 .hook = br_nf_post_routing,
 928                 .owner = THIS_MODULE,
 929                 .pf = PF_BRIDGE,
 930                 .hooknum = NF_BR_POST_ROUTING,
 931                 .priority = NF_BR_PRI_LAST,
 932         },
 933         {
 934                 .hook = ip_sabotage_in,
 935                 .owner = THIS_MODULE,
 936                 .pf = PF_INET,
 937                 .hooknum = NF_INET_PRE_ROUTING,
 938                 .priority = NF_IP_PRI_FIRST,
 939         },
 940         {
 941                 .hook = ip_sabotage_in,
 942                 .owner = THIS_MODULE,
 943                 .pf = PF_INET6,
 944                 .hooknum = NF_INET_PRE_ROUTING,
 945                 .priority = NF_IP6_PRI_FIRST,
 946         },
 947 };
 948
 949 #ifdef CONFIG_SYSCTL
 950 static
 951 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 952                             void __user * buffer, size_t * lenp, loff_t * ppos)
 953 {
 954         int ret;
 955
 956         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 957
 958         if (write && *(int *)(ctl->data))
 959                 *(int *)(ctl->data) = 1;
 960         return ret;
 961 }
 962
 963 static ctl_table brnf_table[] = {
 964         {
 965                 .procname       = "bridge-nf-call-arptables",
 966                 .data           = &brnf_call_arptables,
 967                 .maxlen         = sizeof(int),
 968                 .mode           = 0644,
 969                 .proc_handler   = brnf_sysctl_call_tables,
 970         },
 971         {
 972                 .procname       = "bridge-nf-call-iptables",
 973                 .data           = &brnf_call_iptables,
 974                 .maxlen         = sizeof(int),
 975                 .mode           = 0644,
 976                 .proc_handler   = brnf_sysctl_call_tables,
 977         },
 978         {
 979                 .procname       = "bridge-nf-call-ip6tables",
 980                 .data           = &brnf_call_ip6tables,
 981                 .maxlen         = sizeof(int),
 982                 .mode           = 0644,
 983                 .proc_handler   = brnf_sysctl_call_tables,
 984         },
 985         {
 986                 .procname       = "bridge-nf-filter-vlan-tagged",
 987                 .data           = &brnf_filter_vlan_tagged,
 988                 .maxlen         = sizeof(int),
 989                 .mode           = 0644,
 990                 .proc_handler   = brnf_sysctl_call_tables,
 991         },
 992         {
 993                 .procname       = "bridge-nf-filter-pppoe-tagged",
 994                 .data           = &brnf_filter_pppoe_tagged,
 995                 .maxlen         = sizeof(int),
 996                 .mode           = 0644,
 997                 .proc_handler   = brnf_sysctl_call_tables,
 998         },
 999         { }
1000 };
1001
1002 static struct ctl_path brnf_path[] = {
1003         { .procname = "net", },
1004         { .procname = "bridge", },
1005         { }
1006 };
1007 #endif
1008
1009 int __init br_netfilter_init(void)
1010 {
1011         int ret;
1012
1013         ret = dst_entries_init(&fake_dst_ops);
1014         if (ret < 0)
1015                 return ret;
1016
1017         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1018         if (ret < 0) {
1019                 dst_entries_destroy(&fake_dst_ops);
1020                 return ret;
1021         }
1022 #ifdef CONFIG_SYSCTL
1023         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1024         if (brnf_sysctl_header == NULL) {
1025                 printk(KERN_WARNING
1026                        "br_netfilter: can't register to sysctl.\n");
1027                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1028                 dst_entries_destroy(&fake_dst_ops);
1029                 return -ENOMEM;
1030         }
1031 #endif
1032         printk(KERN_NOTICE "Bridge firewalling registered\n");
1033         return 0;
1034 }
1035
1036 void br_netfilter_fini(void)
1037 {
1038         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1039 #ifdef CONFIG_SYSCTL
1040         unregister_sysctl_table(brnf_sysctl_header);
1041 #endif
1042         dst_entries_destroy(&fake_dst_ops);
1043 }