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 struct dst_ops fake_dst_ops = {
 108         .family =               AF_INET,
 109         .protocol =             cpu_to_be16(ETH_P_IP),
 110         .update_pmtu =          fake_update_pmtu,
 111 };
 112
 113 /*
 114  * Initialize bogus route table used to keep netfilter happy.
 115  * Currently, we fill in the PMTU entry because netfilter
 116  * refragmentation needs it, and the rt_flags entry because
 117  * ipt_REJECT needs it.  Future netfilter modules might
 118  * require us to fill additional fields.
 119  */
 120 void br_netfilter_rtable_init(struct net_bridge *br)
 121 {
 122         struct rtable *rt = &br->fake_rtable;
 123
 124         atomic_set(&rt->dst.__refcnt, 1);
 125         rt->dst.dev = br->dev;
 126         rt->dst.path = &rt->dst;
 127         rt->dst.metrics[RTAX_MTU - 1] = 1500;
 128         rt->dst.flags   = DST_NOXFRM;
 129         rt->dst.ops = &fake_dst_ops;
 130 }
 131
 132 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 133 {
 134         if (!br_port_exists(dev))
 135                 return NULL;
 136         return &br_port_get_rcu(dev)->br->fake_rtable;
 137 }
 138
 139 static inline struct net_device *bridge_parent(const struct net_device *dev)
 140 {
 141         if (!br_port_exists(dev))
 142                 return NULL;
 143
 144         return br_port_get_rcu(dev)->br->dev;
 145 }
 146
 147 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 148 {
 149         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 150         if (likely(skb->nf_bridge))
 151                 atomic_set(&(skb->nf_bridge->use), 1);
 152
 153         return skb->nf_bridge;
 154 }
 155
 156 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 157 {
 158         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 159
 160         if (atomic_read(&nf_bridge->use) > 1) {
 161                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 162
 163                 if (tmp) {
 164                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 165                         atomic_set(&tmp->use, 1);
 166                 }
 167                 nf_bridge_put(nf_bridge);
 168                 nf_bridge = tmp;
 169         }
 170         return nf_bridge;
 171 }
 172
 173 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 174 {
 175         unsigned int len = nf_bridge_encap_header_len(skb);
 176
 177         skb_push(skb, len);
 178         skb->network_header -= len;
 179 }
 180
 181 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 182 {
 183         unsigned int len = nf_bridge_encap_header_len(skb);
 184
 185         skb_pull(skb, len);
 186         skb->network_header += len;
 187 }
 188
 189 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 190 {
 191         unsigned int len = nf_bridge_encap_header_len(skb);
 192
 193         skb_pull_rcsum(skb, len);
 194         skb->network_header += len;
 195 }
 196
 197 static inline void nf_bridge_save_header(struct sk_buff *skb)
 198 {
 199         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 200
 201         skb_copy_from_linear_data_offset(skb, -header_size,
 202                                          skb->nf_bridge->data, header_size);
 203 }
 204
 205 static inline void nf_bridge_update_protocol(struct sk_buff *skb)
 206 {
 207         if (skb->nf_bridge->mask & BRNF_8021Q)
 208                 skb->protocol = htons(ETH_P_8021Q);
 209         else if (skb->nf_bridge->mask & BRNF_PPPoE)
 210                 skb->protocol = htons(ETH_P_PPP_SES);
 211 }
 212
 213 /* When handing a packet over to the IP layer
 214  * check whether we have a skb that is in the
 215  * expected format
 216  */
 217
 218 static int br_parse_ip_options(struct sk_buff *skb)
 219 {
 220         struct ip_options *opt;
 221         struct iphdr *iph;
 222         struct net_device *dev = skb->dev;
 223         u32 len;
 224
 225         iph = ip_hdr(skb);
 226         opt = &(IPCB(skb)->opt);
 227
 228         /* Basic sanity checks */
 229         if (iph->ihl < 5 || iph->version != 4)
 230                 goto inhdr_error;
 231
 232         if (!pskb_may_pull(skb, iph->ihl*4))
 233                 goto inhdr_error;
 234
 235         iph = ip_hdr(skb);
 236         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 237                 goto inhdr_error;
 238
 239         len = ntohs(iph->tot_len);
 240         if (skb->len < len) {
 241                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 242                 goto drop;
 243         } else if (len < (iph->ihl*4))
 244                 goto inhdr_error;
 245
 246         if (pskb_trim_rcsum(skb, len)) {
 247                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 248                 goto drop;
 249         }
 250
 251         /* Zero out the CB buffer if no options present */
 252         if (iph->ihl == 5) {
 253                 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 254                 return 0;
 255         }
 256
 257         opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 258         if (ip_options_compile(dev_net(dev), opt, skb))
 259                 goto inhdr_error;
 260
 261         /* Check correct handling of SRR option */
 262         if (unlikely(opt->srr)) {
 263                 struct in_device *in_dev = __in_dev_get_rcu(dev);
 264                 if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
 265                         goto drop;
 266
 267                 if (ip_options_rcv_srr(skb))
 268                         goto drop;
 269         }
 270
 271         return 0;
 272
 273 inhdr_error:
 274         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 275 drop:
 276         return -1;
 277 }
 278
 279 /* Fill in the header for fragmented IP packets handled by
 280  * the IPv4 connection tracking code.
 281  */
 282 int nf_bridge_copy_header(struct sk_buff *skb)
 283 {
 284         int err;
 285         unsigned int header_size;
 286
 287         nf_bridge_update_protocol(skb);
 288         header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 289         err = skb_cow_head(skb, header_size);
 290         if (err)
 291                 return err;
 292
 293         skb_copy_to_linear_data_offset(skb, -header_size,
 294                                        skb->nf_bridge->data, header_size);
 295         __skb_push(skb, nf_bridge_encap_header_len(skb));
 296         return 0;
 297 }
 298
 299 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 300 /* Undo the changes made for ip6tables PREROUTING and continue the
 301  * bridge PRE_ROUTING hook. */
 302 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 303 {
 304         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 305         struct rtable *rt;
 306
 307         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 308                 skb->pkt_type = PACKET_OTHERHOST;
 309                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 310         }
 311         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 312
 313         rt = bridge_parent_rtable(nf_bridge->physindev);
 314         if (!rt) {
 315                 kfree_skb(skb);
 316                 return 0;
 317         }
 318         skb_dst_set_noref(skb, &rt->dst);
 319
 320         skb->dev = nf_bridge->physindev;
 321         nf_bridge_update_protocol(skb);
 322         nf_bridge_push_encap_header(skb);
 323         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 324                        br_handle_frame_finish, 1);
 325
 326         return 0;
 327 }
 328
 329 /* Obtain the correct destination MAC address, while preserving the original
 330  * source MAC address. If we already know this address, we just copy it. If we
 331  * don't, we use the neighbour framework to find out. In both cases, we make
 332  * sure that br_handle_frame_finish() is called afterwards.
 333  */
 334 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 335 {
 336         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 337         struct dst_entry *dst;
 338
 339         skb->dev = bridge_parent(skb->dev);
 340         if (!skb->dev)
 341                 goto free_skb;
 342         dst = skb_dst(skb);
 343         if (dst->hh) {
 344                 neigh_hh_bridge(dst->hh, skb);
 345                 skb->dev = nf_bridge->physindev;
 346                 return br_handle_frame_finish(skb);
 347         } else if (dst->neighbour) {
 348                 /* the neighbour function below overwrites the complete
 349                  * MAC header, so we save the Ethernet source address and
 350                  * protocol number. */
 351                 skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
 352                 /* tell br_dev_xmit to continue with forwarding */
 353                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 354                 return dst->neighbour->output(skb);
 355         }
 356 free_skb:
 357         kfree_skb(skb);
 358         return 0;
 359 }
 360
 361 /* This requires some explaining. If DNAT has taken place,
 362  * we will need to fix up the destination Ethernet address.
 363  *
 364  * There are two cases to consider:
 365  * 1. The packet was DNAT'ed to a device in the same bridge
 366  *    port group as it was received on. We can still bridge
 367  *    the packet.
 368  * 2. The packet was DNAT'ed to a different device, either
 369  *    a non-bridged device or another bridge port group.
 370  *    The packet will need to be routed.
 371  *
 372  * The correct way of distinguishing between these two cases is to
 373  * call ip_route_input() and to look at skb->dst->dev, which is
 374  * changed to the destination device if ip_route_input() succeeds.
 375  *
 376  * Let's first consider the case that ip_route_input() succeeds:
 377  *
 378  * If the output device equals the logical bridge device the packet
 379  * came in on, we can consider this bridging. The corresponding MAC
 380  * address will be obtained in br_nf_pre_routing_finish_bridge.
 381  * Otherwise, the packet is considered to be routed and we just
 382  * change the destination MAC address so that the packet will
 383  * later be passed up to the IP stack to be routed. For a redirected
 384  * packet, ip_route_input() will give back the localhost as output device,
 385  * which differs from the bridge device.
 386  *
 387  * Let's now consider the case that ip_route_input() fails:
 388  *
 389  * This can be because the destination address is martian, in which case
 390  * the packet will be dropped.
 391  * If IP forwarding is disabled, ip_route_input() will fail, while
 392  * ip_route_output_key() can return success. The source
 393  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 394  * thinks we're handling a locally generated packet and won't care
 395  * if IP forwarding is enabled. If the output device equals the logical bridge
 396  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 397  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 398  */
 399 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 400 {
 401         struct net_device *dev = skb->dev;
 402         struct iphdr *iph = ip_hdr(skb);
 403         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 404         struct rtable *rt;
 405         int err;
 406
 407         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 408                 skb->pkt_type = PACKET_OTHERHOST;
 409                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 410         }
 411         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 412         if (dnat_took_place(skb)) {
 413                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 414                         struct flowi fl = {
 415                                 .nl_u = {
 416                                         .ip4_u = {
 417                                                  .daddr = iph->daddr,
 418                                                  .saddr = 0,
 419                                                  .tos = RT_TOS(iph->tos) },
 420                                 },
 421                                 .proto = 0,
 422                         };
 423                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 424
 425                         /* If err equals -EHOSTUNREACH the error is due to a
 426                          * martian destination or due to the fact that
 427                          * forwarding is disabled. For most martian packets,
 428                          * ip_route_output_key() will fail. It won't fail for 2 types of
 429                          * martian destinations: loopback destinations and destination
 430                          * 0.0.0.0. In both cases the packet will be dropped because the
 431                          * destination is the loopback device and not the bridge. */
 432                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 433                                 goto free_skb;
 434
 435                         if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 436                                 /* - Bridged-and-DNAT'ed traffic doesn't
 437                                  *   require ip_forwarding. */
 438                                 if (((struct dst_entry *)rt)->dev == dev) {
 439                                         skb_dst_set(skb, (struct dst_entry *)rt);
 440                                         goto bridged_dnat;
 441                                 }
 442                                 dst_release((struct dst_entry *)rt);
 443                         }
 444 free_skb:
 445                         kfree_skb(skb);
 446                         return 0;
 447                 } else {
 448                         if (skb_dst(skb)->dev == dev) {
 449 bridged_dnat:
 450                                 skb->dev = nf_bridge->physindev;
 451                                 nf_bridge_update_protocol(skb);
 452                                 nf_bridge_push_encap_header(skb);
 453                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 454                                                NF_BR_PRE_ROUTING,
 455                                                skb, skb->dev, NULL,
 456                                                br_nf_pre_routing_finish_bridge,
 457                                                1);
 458                                 return 0;
 459                         }
 460                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 461                         skb->pkt_type = PACKET_HOST;
 462                 }
 463         } else {
 464                 rt = bridge_parent_rtable(nf_bridge->physindev);
 465                 if (!rt) {
 466                         kfree_skb(skb);
 467                         return 0;
 468                 }
 469                 skb_dst_set_noref(skb, &rt->dst);
 470         }
 471
 472         skb->dev = nf_bridge->physindev;
 473         nf_bridge_update_protocol(skb);
 474         nf_bridge_push_encap_header(skb);
 475         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 476                        br_handle_frame_finish, 1);
 477
 478         return 0;
 479 }
 480
 481 /* Some common code for IPv4/IPv6 */
 482 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 483 {
 484         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 485
 486         if (skb->pkt_type == PACKET_OTHERHOST) {
 487                 skb->pkt_type = PACKET_HOST;
 488                 nf_bridge->mask |= BRNF_PKT_TYPE;
 489         }
 490
 491         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 492         nf_bridge->physindev = skb->dev;
 493         skb->dev = bridge_parent(skb->dev);
 494         if (skb->protocol == htons(ETH_P_8021Q))
 495                 nf_bridge->mask |= BRNF_8021Q;
 496         else if (skb->protocol == htons(ETH_P_PPP_SES))
 497                 nf_bridge->mask |= BRNF_PPPoE;
 498
 499         return skb->dev;
 500 }
 501
 502 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 503 static int check_hbh_len(struct sk_buff *skb)
 504 {
 505         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 506         u32 pkt_len;
 507         const unsigned char *nh = skb_network_header(skb);
 508         int off = raw - nh;
 509         int len = (raw[1] + 1) << 3;
 510
 511         if ((raw + len) - skb->data > skb_headlen(skb))
 512                 goto bad;
 513
 514         off += 2;
 515         len -= 2;
 516
 517         while (len > 0) {
 518                 int optlen = nh[off + 1] + 2;
 519
 520                 switch (nh[off]) {
 521                 case IPV6_TLV_PAD0:
 522                         optlen = 1;
 523                         break;
 524
 525                 case IPV6_TLV_PADN:
 526                         break;
 527
 528                 case IPV6_TLV_JUMBO:
 529                         if (nh[off + 1] != 4 || (off & 3) != 2)
 530                                 goto bad;
 531                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 532                         if (pkt_len <= IPV6_MAXPLEN ||
 533                             ipv6_hdr(skb)->payload_len)
 534                                 goto bad;
 535                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 536                                 goto bad;
 537                         if (pskb_trim_rcsum(skb,
 538                                             pkt_len + sizeof(struct ipv6hdr)))
 539                                 goto bad;
 540                         nh = skb_network_header(skb);
 541                         break;
 542                 default:
 543                         if (optlen > len)
 544                                 goto bad;
 545                         break;
 546                 }
 547                 off += optlen;
 548                 len -= optlen;
 549         }
 550         if (len == 0)
 551                 return 0;
 552 bad:
 553         return -1;
 554
 555 }
 556
 557 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 558  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 559 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 560                                            struct sk_buff *skb,
 561                                            const struct net_device *in,
 562                                            const struct net_device *out,
 563                                            int (*okfn)(struct sk_buff *))
 564 {
 565         struct ipv6hdr *hdr;
 566         u32 pkt_len;
 567
 568         if (skb->len < sizeof(struct ipv6hdr))
 569                 goto inhdr_error;
 570
 571         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 572                 goto inhdr_error;
 573
 574         hdr = ipv6_hdr(skb);
 575
 576         if (hdr->version != 6)
 577                 goto inhdr_error;
 578
 579         pkt_len = ntohs(hdr->payload_len);
 580
 581         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 582                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 583                         goto inhdr_error;
 584                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 585                         goto inhdr_error;
 586         }
 587         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 588                 goto inhdr_error;
 589
 590         nf_bridge_put(skb->nf_bridge);
 591         if (!nf_bridge_alloc(skb))
 592                 return NF_DROP;
 593         if (!setup_pre_routing(skb))
 594                 return NF_DROP;
 595
 596         skb->protocol = htons(ETH_P_IPV6);
 597         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 598                 br_nf_pre_routing_finish_ipv6);
 599
 600         return NF_STOLEN;
 601
 602 inhdr_error:
 603         return NF_DROP;
 604 }
 605
 606 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 607  * Replicate the checks that IPv4 does on packet reception.
 608  * Set skb->dev to the bridge device (i.e. parent of the
 609  * receiving device) to make netfilter happy, the REDIRECT
 610  * target in particular.  Save the original destination IP
 611  * address to be able to detect DNAT afterwards. */
 612 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 613                                       const struct net_device *in,
 614                                       const struct net_device *out,
 615                                       int (*okfn)(struct sk_buff *))
 616 {
 617         struct net_bridge_port *p;
 618         struct net_bridge *br;
 619         __u32 len = nf_bridge_encap_header_len(skb);
 620
 621         if (unlikely(!pskb_may_pull(skb, len)))
 622                 goto out;
 623
 624         p = br_port_get_rcu(in);
 625         if (p == NULL)
 626                 goto out;
 627         br = p->br;
 628
 629         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 630             IS_PPPOE_IPV6(skb)) {
 631                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 632                         return NF_ACCEPT;
 633
 634                 nf_bridge_pull_encap_header_rcsum(skb);
 635                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 636         }
 637
 638         if (!brnf_call_iptables && !br->nf_call_iptables)
 639                 return NF_ACCEPT;
 640
 641         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 642             !IS_PPPOE_IP(skb))
 643                 return NF_ACCEPT;
 644
 645         nf_bridge_pull_encap_header_rcsum(skb);
 646
 647         if (br_parse_ip_options(skb))
 648                 /* Drop invalid packet */
 649                 goto out;
 650
 651         nf_bridge_put(skb->nf_bridge);
 652         if (!nf_bridge_alloc(skb))
 653                 return NF_DROP;
 654         if (!setup_pre_routing(skb))
 655                 return NF_DROP;
 656         store_orig_dstaddr(skb);
 657         skb->protocol = htons(ETH_P_IP);
 658
 659         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 660                 br_nf_pre_routing_finish);
 661
 662         return NF_STOLEN;
 663
 664 out:
 665         return NF_DROP;
 666 }
 667
 668
 669 /* PF_BRIDGE/LOCAL_IN ************************************************/
 670 /* The packet is locally destined, which requires a real
 671  * dst_entry, so detach the fake one.  On the way up, the
 672  * packet would pass through PRE_ROUTING again (which already
 673  * took place when the packet entered the bridge), but we
 674  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 675  * prevent this from happening. */
 676 static unsigned int br_nf_local_in(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 rtable *rt = skb_rtable(skb);
 682
 683         if (rt && rt == bridge_parent_rtable(in))
 684                 skb_dst_drop(skb);
 685
 686         return NF_ACCEPT;
 687 }
 688
 689 /* PF_BRIDGE/FORWARD *************************************************/
 690 static int br_nf_forward_finish(struct sk_buff *skb)
 691 {
 692         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 693         struct net_device *in;
 694
 695         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 696                 in = nf_bridge->physindev;
 697                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 698                         skb->pkt_type = PACKET_OTHERHOST;
 699                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 700                 }
 701                 nf_bridge_update_protocol(skb);
 702         } else {
 703                 in = *((struct net_device **)(skb->cb));
 704         }
 705         nf_bridge_push_encap_header(skb);
 706
 707         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 708                        skb->dev, br_forward_finish, 1);
 709         return 0;
 710 }
 711
 712 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 713  * netfilter with indev and outdev set to the bridge device,
 714  * but we are still able to filter on the 'real' indev/outdev
 715  * because of the physdev module. For ARP, indev and outdev are the
 716  * bridge ports. */
 717 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 718                                      const struct net_device *in,
 719                                      const struct net_device *out,
 720                                      int (*okfn)(struct sk_buff *))
 721 {
 722         struct nf_bridge_info *nf_bridge;
 723         struct net_device *parent;
 724         u_int8_t pf;
 725
 726         if (!skb->nf_bridge)
 727                 return NF_ACCEPT;
 728
 729         /* Need exclusive nf_bridge_info since we might have multiple
 730          * different physoutdevs. */
 731         if (!nf_bridge_unshare(skb))
 732                 return NF_DROP;
 733
 734         parent = bridge_parent(out);
 735         if (!parent)
 736                 return NF_DROP;
 737
 738         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 739             IS_PPPOE_IP(skb))
 740                 pf = PF_INET;
 741         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 742                  IS_PPPOE_IPV6(skb))
 743                 pf = PF_INET6;
 744         else
 745                 return NF_ACCEPT;
 746
 747         nf_bridge_pull_encap_header(skb);
 748
 749         nf_bridge = skb->nf_bridge;
 750         if (skb->pkt_type == PACKET_OTHERHOST) {
 751                 skb->pkt_type = PACKET_HOST;
 752                 nf_bridge->mask |= BRNF_PKT_TYPE;
 753         }
 754
 755         /* The physdev module checks on this */
 756         nf_bridge->mask |= BRNF_BRIDGED;
 757         nf_bridge->physoutdev = skb->dev;
 758         if (pf == PF_INET)
 759                 skb->protocol = htons(ETH_P_IP);
 760         else
 761                 skb->protocol = htons(ETH_P_IPV6);
 762
 763         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 764                 br_nf_forward_finish);
 765
 766         return NF_STOLEN;
 767 }
 768
 769 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 770                                       const struct net_device *in,
 771                                       const struct net_device *out,
 772                                       int (*okfn)(struct sk_buff *))
 773 {
 774         struct net_bridge_port *p;
 775         struct net_bridge *br;
 776         struct net_device **d = (struct net_device **)(skb->cb);
 777
 778         p = br_port_get_rcu(out);
 779         if (p == NULL)
 780                 return NF_ACCEPT;
 781         br = p->br;
 782
 783         if (!brnf_call_arptables && !br->nf_call_arptables)
 784                 return NF_ACCEPT;
 785
 786         if (skb->protocol != htons(ETH_P_ARP)) {
 787                 if (!IS_VLAN_ARP(skb))
 788                         return NF_ACCEPT;
 789                 nf_bridge_pull_encap_header(skb);
 790         }
 791
 792         if (arp_hdr(skb)->ar_pln != 4) {
 793                 if (IS_VLAN_ARP(skb))
 794                         nf_bridge_push_encap_header(skb);
 795                 return NF_ACCEPT;
 796         }
 797         *d = (struct net_device *)in;
 798         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 799                 (struct net_device *)out, br_nf_forward_finish);
 800
 801         return NF_STOLEN;
 802 }
 803
 804 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 805 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 806 {
 807         int ret;
 808
 809         if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
 810             skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
 811             !skb_is_gso(skb)) {
 812                 if (br_parse_ip_options(skb))
 813                         /* Drop invalid packet */
 814                         return NF_DROP;
 815                 ret = ip_fragment(skb, br_dev_queue_push_xmit);
 816         } else
 817                 ret = br_dev_queue_push_xmit(skb);
 818
 819         return ret;
 820 }
 821 #else
 822 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 823 {
 824         return br_dev_queue_push_xmit(skb);
 825 }
 826 #endif
 827
 828 /* PF_BRIDGE/POST_ROUTING ********************************************/
 829 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 830                                        const struct net_device *in,
 831                                        const struct net_device *out,
 832                                        int (*okfn)(struct sk_buff *))
 833 {
 834         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 835         struct net_device *realoutdev = bridge_parent(skb->dev);
 836         u_int8_t pf;
 837
 838         if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 839                 return NF_ACCEPT;
 840
 841         if (!realoutdev)
 842                 return NF_DROP;
 843
 844         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 845             IS_PPPOE_IP(skb))
 846                 pf = PF_INET;
 847         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 848                  IS_PPPOE_IPV6(skb))
 849                 pf = PF_INET6;
 850         else
 851                 return NF_ACCEPT;
 852
 853         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 854          * about the value of skb->pkt_type. */
 855         if (skb->pkt_type == PACKET_OTHERHOST) {
 856                 skb->pkt_type = PACKET_HOST;
 857                 nf_bridge->mask |= BRNF_PKT_TYPE;
 858         }
 859
 860         nf_bridge_pull_encap_header(skb);
 861         nf_bridge_save_header(skb);
 862         if (pf == PF_INET)
 863                 skb->protocol = htons(ETH_P_IP);
 864         else
 865                 skb->protocol = htons(ETH_P_IPV6);
 866
 867         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 868                 br_nf_dev_queue_xmit);
 869
 870         return NF_STOLEN;
 871 }
 872
 873 /* IP/SABOTAGE *****************************************************/
 874 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 875  * for the second time. */
 876 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 877                                    const struct net_device *in,
 878                                    const struct net_device *out,
 879                                    int (*okfn)(struct sk_buff *))
 880 {
 881         if (skb->nf_bridge &&
 882             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 883                 return NF_STOP;
 884         }
 885
 886         return NF_ACCEPT;
 887 }
 888
 889 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 890  * br_dev_queue_push_xmit is called afterwards */
 891 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 892         {
 893                 .hook = br_nf_pre_routing,
 894                 .owner = THIS_MODULE,
 895                 .pf = PF_BRIDGE,
 896                 .hooknum = NF_BR_PRE_ROUTING,
 897                 .priority = NF_BR_PRI_BRNF,
 898         },
 899         {
 900                 .hook = br_nf_local_in,
 901                 .owner = THIS_MODULE,
 902                 .pf = PF_BRIDGE,
 903                 .hooknum = NF_BR_LOCAL_IN,
 904                 .priority = NF_BR_PRI_BRNF,
 905         },
 906         {
 907                 .hook = br_nf_forward_ip,
 908                 .owner = THIS_MODULE,
 909                 .pf = PF_BRIDGE,
 910                 .hooknum = NF_BR_FORWARD,
 911                 .priority = NF_BR_PRI_BRNF - 1,
 912         },
 913         {
 914                 .hook = br_nf_forward_arp,
 915                 .owner = THIS_MODULE,
 916                 .pf = PF_BRIDGE,
 917                 .hooknum = NF_BR_FORWARD,
 918                 .priority = NF_BR_PRI_BRNF,
 919         },
 920         {
 921                 .hook = br_nf_post_routing,
 922                 .owner = THIS_MODULE,
 923                 .pf = PF_BRIDGE,
 924                 .hooknum = NF_BR_POST_ROUTING,
 925                 .priority = NF_BR_PRI_LAST,
 926         },
 927         {
 928                 .hook = ip_sabotage_in,
 929                 .owner = THIS_MODULE,
 930                 .pf = PF_INET,
 931                 .hooknum = NF_INET_PRE_ROUTING,
 932                 .priority = NF_IP_PRI_FIRST,
 933         },
 934         {
 935                 .hook = ip_sabotage_in,
 936                 .owner = THIS_MODULE,
 937                 .pf = PF_INET6,
 938                 .hooknum = NF_INET_PRE_ROUTING,
 939                 .priority = NF_IP6_PRI_FIRST,
 940         },
 941 };
 942
 943 #ifdef CONFIG_SYSCTL
 944 static
 945 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 946                             void __user * buffer, size_t * lenp, loff_t * ppos)
 947 {
 948         int ret;
 949
 950         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 951
 952         if (write && *(int *)(ctl->data))
 953                 *(int *)(ctl->data) = 1;
 954         return ret;
 955 }
 956
 957 static ctl_table brnf_table[] = {
 958         {
 959                 .procname       = "bridge-nf-call-arptables",
 960                 .data           = &brnf_call_arptables,
 961                 .maxlen         = sizeof(int),
 962                 .mode           = 0644,
 963                 .proc_handler   = brnf_sysctl_call_tables,
 964         },
 965         {
 966                 .procname       = "bridge-nf-call-iptables",
 967                 .data           = &brnf_call_iptables,
 968                 .maxlen         = sizeof(int),
 969                 .mode           = 0644,
 970                 .proc_handler   = brnf_sysctl_call_tables,
 971         },
 972         {
 973                 .procname       = "bridge-nf-call-ip6tables",
 974                 .data           = &brnf_call_ip6tables,
 975                 .maxlen         = sizeof(int),
 976                 .mode           = 0644,
 977                 .proc_handler   = brnf_sysctl_call_tables,
 978         },
 979         {
 980                 .procname       = "bridge-nf-filter-vlan-tagged",
 981                 .data           = &brnf_filter_vlan_tagged,
 982                 .maxlen         = sizeof(int),
 983                 .mode           = 0644,
 984                 .proc_handler   = brnf_sysctl_call_tables,
 985         },
 986         {
 987                 .procname       = "bridge-nf-filter-pppoe-tagged",
 988                 .data           = &brnf_filter_pppoe_tagged,
 989                 .maxlen         = sizeof(int),
 990                 .mode           = 0644,
 991                 .proc_handler   = brnf_sysctl_call_tables,
 992         },
 993         { }
 994 };
 995
 996 static struct ctl_path brnf_path[] = {
 997         { .procname = "net", },
 998         { .procname = "bridge", },
 999         { }
1000 };
1001 #endif
1002
1003 int __init br_netfilter_init(void)
1004 {
1005         int ret;
1006
1007         ret = dst_entries_init(&fake_dst_ops);
1008         if (ret < 0)
1009                 return ret;
1010
1011         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1012         if (ret < 0) {
1013                 dst_entries_destroy(&fake_dst_ops);
1014                 return ret;
1015         }
1016 #ifdef CONFIG_SYSCTL
1017         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1018         if (brnf_sysctl_header == NULL) {
1019                 printk(KERN_WARNING
1020                        "br_netfilter: can't register to sysctl.\n");
1021                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1022                 dst_entries_destroy(&fake_dst_ops);
1023                 return -ENOMEM;
1024         }
1025 #endif
1026         printk(KERN_NOTICE "Bridge firewalling registered\n");
1027         return 0;
1028 }
1029
1030 void br_netfilter_fini(void)
1031 {
1032         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1033 #ifdef CONFIG_SYSCTL
1034         unregister_sysctl_table(brnf_sysctl_header);
1035 #endif
1036         dst_entries_destroy(&fake_dst_ops);
1037 }