net/bridge/br_netfilter.c

   1 /*
   2  *      Handle firewalling
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *      Bart De Schuymer                <bdschuym@pandora.be>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Lennert dedicates this file to Kerstin Wurdinger.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/ip.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/skbuff.h>
  22 #include <linux/if_arp.h>
  23 #include <linux/if_ether.h>
  24 #include <linux/if_vlan.h>
  25 #include <linux/if_pppox.h>
  26 #include <linux/ppp_defs.h>
  27 #include <linux/netfilter_bridge.h>
  28 #include <linux/netfilter_ipv4.h>
  29 #include <linux/netfilter_ipv6.h>
  30 #include <linux/netfilter_arp.h>
  31 #include <linux/in_route.h>
  32 #include <linux/inetdevice.h>
  33
  34 #include <net/ip.h>
  35 #include <net/ipv6.h>
  36 #include <net/route.h>
  37
  38 #include <asm/uaccess.h>
  39 #include "br_private.h"
  40 #ifdef CONFIG_SYSCTL
  41 #include <linux/sysctl.h>
  42 #endif
  43
  44 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  45                                  (skb->nf_bridge->data))->daddr.ipv4)
  46 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  47 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  48
  49 #ifdef CONFIG_SYSCTL
  50 static struct ctl_table_header *brnf_sysctl_header;
  51 static int brnf_call_iptables __read_mostly = 1;
  52 static int brnf_call_ip6tables __read_mostly = 1;
  53 static int brnf_call_arptables __read_mostly = 1;
  54 static int brnf_filter_vlan_tagged __read_mostly = 0;
  55 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  56 #else
  57 #define brnf_filter_vlan_tagged 0
  58 #define brnf_filter_pppoe_tagged 0
  59 #endif
  60
  61 static inline __be16 vlan_proto(const struct sk_buff *skb)
  62 {
  63         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  64 }
  65
  66 #define IS_VLAN_IP(skb) \
  67         (skb->protocol == htons(ETH_P_8021Q) && \
  68          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  69          brnf_filter_vlan_tagged)
  70
  71 #define IS_VLAN_IPV6(skb) \
  72         (skb->protocol == htons(ETH_P_8021Q) && \
  73          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  74          brnf_filter_vlan_tagged)
  75
  76 #define IS_VLAN_ARP(skb) \
  77         (skb->protocol == htons(ETH_P_8021Q) && \
  78          vlan_proto(skb) == htons(ETH_P_ARP) && \
  79          brnf_filter_vlan_tagged)
  80
  81 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  82 {
  83         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  84                             sizeof(struct pppoe_hdr)));
  85 }
  86
  87 #define IS_PPPOE_IP(skb) \
  88         (skb->protocol == htons(ETH_P_PPP_SES) && \
  89          pppoe_proto(skb) == htons(PPP_IP) && \
  90          brnf_filter_pppoe_tagged)
  91
  92 #define IS_PPPOE_IPV6(skb) \
  93         (skb->protocol == htons(ETH_P_PPP_SES) && \
  94          pppoe_proto(skb) == htons(PPP_IPV6) && \
  95          brnf_filter_pppoe_tagged)
  96
  97 static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
  98 {
  99 }
 100
 101 static struct dst_ops fake_dst_ops = {
 102         .family =               AF_INET,
 103         .protocol =             cpu_to_be16(ETH_P_IP),
 104         .update_pmtu =          fake_update_pmtu,
 105         .entries =              ATOMIC_INIT(0),
 106 };
 107
 108 /*
 109  * Initialize bogus route table used to keep netfilter happy.
 110  * Currently, we fill in the PMTU entry because netfilter
 111  * refragmentation needs it, and the rt_flags entry because
 112  * ipt_REJECT needs it.  Future netfilter modules might
 113  * require us to fill additional fields.
 114  */
 115 void br_netfilter_rtable_init(struct net_bridge *br)
 116 {
 117         struct rtable *rt = &br->fake_rtable;
 118
 119         atomic_set(&rt->u.dst.__refcnt, 1);
 120         rt->u.dst.dev = br->dev;
 121         rt->u.dst.path = &rt->u.dst;
 122         rt->u.dst.metrics[RTAX_MTU - 1] = 1500;
 123         rt->u.dst.flags = DST_NOXFRM;
 124         rt->u.dst.ops = &fake_dst_ops;
 125 }
 126
 127 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 128 {
 129         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 130
 131         return port ? &port->br->fake_rtable : NULL;
 132 }
 133
 134 static inline struct net_device *bridge_parent(const struct net_device *dev)
 135 {
 136         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 137
 138         return port ? port->br->dev : NULL;
 139 }
 140
 141 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 142 {
 143         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 144         if (likely(skb->nf_bridge))
 145                 atomic_set(&(skb->nf_bridge->use), 1);
 146
 147         return skb->nf_bridge;
 148 }
 149
 150 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 151 {
 152         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 153
 154         if (atomic_read(&nf_bridge->use) > 1) {
 155                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 156
 157                 if (tmp) {
 158                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 159                         atomic_set(&tmp->use, 1);
 160                         nf_bridge_put(nf_bridge);
 161                 }
 162                 nf_bridge = tmp;
 163         }
 164         return nf_bridge;
 165 }
 166
 167 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 168 {
 169         unsigned int len = nf_bridge_encap_header_len(skb);
 170
 171         skb_push(skb, len);
 172         skb->network_header -= len;
 173 }
 174
 175 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 176 {
 177         unsigned int len = nf_bridge_encap_header_len(skb);
 178
 179         skb_pull(skb, len);
 180         skb->network_header += len;
 181 }
 182
 183 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 184 {
 185         unsigned int len = nf_bridge_encap_header_len(skb);
 186
 187         skb_pull_rcsum(skb, len);
 188         skb->network_header += len;
 189 }
 190
 191 static inline void nf_bridge_save_header(struct sk_buff *skb)
 192 {
 193         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 194
 195         skb_copy_from_linear_data_offset(skb, -header_size,
 196                                          skb->nf_bridge->data, header_size);
 197 }
 198
 199 /*
 200  * When forwarding bridge frames, we save a copy of the original
 201  * header before processing.
 202  */
 203 int nf_bridge_copy_header(struct sk_buff *skb)
 204 {
 205         int err;
 206         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 207
 208         err = skb_cow_head(skb, header_size);
 209         if (err)
 210                 return err;
 211
 212         skb_copy_to_linear_data_offset(skb, -header_size,
 213                                        skb->nf_bridge->data, header_size);
 214         __skb_push(skb, nf_bridge_encap_header_len(skb));
 215         return 0;
 216 }
 217
 218 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 219 /* Undo the changes made for ip6tables PREROUTING and continue the
 220  * bridge PRE_ROUTING hook. */
 221 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 222 {
 223         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 224         struct rtable *rt;
 225
 226         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 227                 skb->pkt_type = PACKET_OTHERHOST;
 228                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 229         }
 230         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 231
 232         rt = bridge_parent_rtable(nf_bridge->physindev);
 233         if (!rt) {
 234                 kfree_skb(skb);
 235                 return 0;
 236         }
 237         dst_hold(&rt->u.dst);
 238         skb_dst_set(skb, &rt->u.dst);
 239
 240         skb->dev = nf_bridge->physindev;
 241         nf_bridge_push_encap_header(skb);
 242         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 243                        br_handle_frame_finish, 1);
 244
 245         return 0;
 246 }
 247
 248 /* This requires some explaining. If DNAT has taken place,
 249  * we will need to fix up the destination Ethernet address,
 250  * and this is a tricky process.
 251  *
 252  * There are two cases to consider:
 253  * 1. The packet was DNAT'ed to a device in the same bridge
 254  *    port group as it was received on. We can still bridge
 255  *    the packet.
 256  * 2. The packet was DNAT'ed to a different device, either
 257  *    a non-bridged device or another bridge port group.
 258  *    The packet will need to be routed.
 259  *
 260  * The correct way of distinguishing between these two cases is to
 261  * call ip_route_input() and to look at skb->dst->dev, which is
 262  * changed to the destination device if ip_route_input() succeeds.
 263  *
 264  * Let us first consider the case that ip_route_input() succeeds:
 265  *
 266  * If skb->dst->dev equals the logical bridge device the packet
 267  * came in on, we can consider this bridging. The packet is passed
 268  * through the neighbour output function to build a new destination
 269  * MAC address, which will make the packet enter br_nf_local_out()
 270  * not much later. In that function it is assured that the iptables
 271  * FORWARD chain is traversed for the packet.
 272  *
 273  * Otherwise, the packet is considered to be routed and we just
 274  * change the destination MAC address so that the packet will
 275  * later be passed up to the IP stack to be routed. For a redirected
 276  * packet, ip_route_input() will give back the localhost as output device,
 277  * which differs from the bridge device.
 278  *
 279  * Let us now consider the case that ip_route_input() fails:
 280  *
 281  * This can be because the destination address is martian, in which case
 282  * the packet will be dropped.
 283  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 284  * will fail, while __ip_route_output_key() will return success. The source
 285  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 286  * thinks we're handling a locally generated packet and won't care
 287  * if IP forwarding is allowed. We send a warning message to the users's
 288  * log telling her to put IP forwarding on.
 289  *
 290  * ip_route_input() will also fail if there is no route available.
 291  * In that case we just drop the packet.
 292  *
 293  * --Lennert, 20020411
 294  * --Bart, 20020416 (updated)
 295  * --Bart, 20021007 (updated)
 296  * --Bart, 20062711 (updated) */
 297 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 298 {
 299         if (skb->pkt_type == PACKET_OTHERHOST) {
 300                 skb->pkt_type = PACKET_HOST;
 301                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 302         }
 303         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 304
 305         skb->dev = bridge_parent(skb->dev);
 306         if (skb->dev) {
 307                 struct dst_entry *dst = skb_dst(skb);
 308
 309                 nf_bridge_pull_encap_header(skb);
 310
 311                 if (dst->hh)
 312                         return neigh_hh_output(dst->hh, skb);
 313                 else if (dst->neighbour)
 314                         return dst->neighbour->output(skb);
 315         }
 316         kfree_skb(skb);
 317         return 0;
 318 }
 319
 320 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 321 {
 322         struct net_device *dev = skb->dev;
 323         struct iphdr *iph = ip_hdr(skb);
 324         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 325         struct rtable *rt;
 326         int err;
 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         if (dnat_took_place(skb)) {
 334                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 335                         struct flowi fl = {
 336                                 .nl_u = {
 337                                         .ip4_u = {
 338                                                  .daddr = iph->daddr,
 339                                                  .saddr = 0,
 340                                                  .tos = RT_TOS(iph->tos) },
 341                                 },
 342                                 .proto = 0,
 343                         };
 344                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 345
 346                         /* If err equals -EHOSTUNREACH the error is due to a
 347                          * martian destination or due to the fact that
 348                          * forwarding is disabled. For most martian packets,
 349                          * ip_route_output_key() will fail. It won't fail for 2 types of
 350                          * martian destinations: loopback destinations and destination
 351                          * 0.0.0.0. In both cases the packet will be dropped because the
 352                          * destination is the loopback device and not the bridge. */
 353                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 354                                 goto free_skb;
 355
 356                         if (!ip_route_output_key(dev_net(dev), &rt, &fl)) {
 357                                 /* - Bridged-and-DNAT'ed traffic doesn't
 358                                  *   require ip_forwarding. */
 359                                 if (((struct dst_entry *)rt)->dev == dev) {
 360                                         skb_dst_set(skb, (struct dst_entry *)rt);
 361                                         goto bridged_dnat;
 362                                 }
 363                                 dst_release((struct dst_entry *)rt);
 364                         }
 365 free_skb:
 366                         kfree_skb(skb);
 367                         return 0;
 368                 } else {
 369                         if (skb_dst(skb)->dev == dev) {
 370 bridged_dnat:
 371                                 /* Tell br_nf_local_out this is a
 372                                  * bridged frame */
 373                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 374                                 skb->dev = nf_bridge->physindev;
 375                                 nf_bridge_push_encap_header(skb);
 376                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 377                                                NF_BR_PRE_ROUTING,
 378                                                skb, skb->dev, NULL,
 379                                                br_nf_pre_routing_finish_bridge,
 380                                                1);
 381                                 return 0;
 382                         }
 383                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 384                         skb->pkt_type = PACKET_HOST;
 385                 }
 386         } else {
 387                 rt = bridge_parent_rtable(nf_bridge->physindev);
 388                 if (!rt) {
 389                         kfree_skb(skb);
 390                         return 0;
 391                 }
 392                 dst_hold(&rt->u.dst);
 393                 skb_dst_set(skb, &rt->u.dst);
 394         }
 395
 396         skb->dev = nf_bridge->physindev;
 397         nf_bridge_push_encap_header(skb);
 398         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 399                        br_handle_frame_finish, 1);
 400
 401         return 0;
 402 }
 403
 404 /* Some common code for IPv4/IPv6 */
 405 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 406 {
 407         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 408
 409         if (skb->pkt_type == PACKET_OTHERHOST) {
 410                 skb->pkt_type = PACKET_HOST;
 411                 nf_bridge->mask |= BRNF_PKT_TYPE;
 412         }
 413
 414         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 415         nf_bridge->physindev = skb->dev;
 416         skb->dev = bridge_parent(skb->dev);
 417
 418         return skb->dev;
 419 }
 420
 421 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 422 static int check_hbh_len(struct sk_buff *skb)
 423 {
 424         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 425         u32 pkt_len;
 426         const unsigned char *nh = skb_network_header(skb);
 427         int off = raw - nh;
 428         int len = (raw[1] + 1) << 3;
 429
 430         if ((raw + len) - skb->data > skb_headlen(skb))
 431                 goto bad;
 432
 433         off += 2;
 434         len -= 2;
 435
 436         while (len > 0) {
 437                 int optlen = nh[off + 1] + 2;
 438
 439                 switch (nh[off]) {
 440                 case IPV6_TLV_PAD0:
 441                         optlen = 1;
 442                         break;
 443
 444                 case IPV6_TLV_PADN:
 445                         break;
 446
 447                 case IPV6_TLV_JUMBO:
 448                         if (nh[off + 1] != 4 || (off & 3) != 2)
 449                                 goto bad;
 450                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 451                         if (pkt_len <= IPV6_MAXPLEN ||
 452                             ipv6_hdr(skb)->payload_len)
 453                                 goto bad;
 454                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 455                                 goto bad;
 456                         if (pskb_trim_rcsum(skb,
 457                                             pkt_len + sizeof(struct ipv6hdr)))
 458                                 goto bad;
 459                         nh = skb_network_header(skb);
 460                         break;
 461                 default:
 462                         if (optlen > len)
 463                                 goto bad;
 464                         break;
 465                 }
 466                 off += optlen;
 467                 len -= optlen;
 468         }
 469         if (len == 0)
 470                 return 0;
 471 bad:
 472         return -1;
 473
 474 }
 475
 476 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 477  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 478 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 479                                            struct sk_buff *skb,
 480                                            const struct net_device *in,
 481                                            const struct net_device *out,
 482                                            int (*okfn)(struct sk_buff *))
 483 {
 484         struct ipv6hdr *hdr;
 485         u32 pkt_len;
 486
 487         if (skb->len < sizeof(struct ipv6hdr))
 488                 goto inhdr_error;
 489
 490         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 491                 goto inhdr_error;
 492
 493         hdr = ipv6_hdr(skb);
 494
 495         if (hdr->version != 6)
 496                 goto inhdr_error;
 497
 498         pkt_len = ntohs(hdr->payload_len);
 499
 500         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 501                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 502                         goto inhdr_error;
 503                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 504                         goto inhdr_error;
 505         }
 506         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 507                 goto inhdr_error;
 508
 509         nf_bridge_put(skb->nf_bridge);
 510         if (!nf_bridge_alloc(skb))
 511                 return NF_DROP;
 512         if (!setup_pre_routing(skb))
 513                 return NF_DROP;
 514
 515         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 516                 br_nf_pre_routing_finish_ipv6);
 517
 518         return NF_STOLEN;
 519
 520 inhdr_error:
 521         return NF_DROP;
 522 }
 523
 524 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 525  * Replicate the checks that IPv4 does on packet reception.
 526  * Set skb->dev to the bridge device (i.e. parent of the
 527  * receiving device) to make netfilter happy, the REDIRECT
 528  * target in particular.  Save the original destination IP
 529  * address to be able to detect DNAT afterwards. */
 530 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 531                                       const struct net_device *in,
 532                                       const struct net_device *out,
 533                                       int (*okfn)(struct sk_buff *))
 534 {
 535         struct iphdr *iph;
 536         __u32 len = nf_bridge_encap_header_len(skb);
 537
 538         if (unlikely(!pskb_may_pull(skb, len)))
 539                 goto out;
 540
 541         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 542             IS_PPPOE_IPV6(skb)) {
 543 #ifdef CONFIG_SYSCTL
 544                 if (!brnf_call_ip6tables)
 545                         return NF_ACCEPT;
 546 #endif
 547                 nf_bridge_pull_encap_header_rcsum(skb);
 548                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 549         }
 550 #ifdef CONFIG_SYSCTL
 551         if (!brnf_call_iptables)
 552                 return NF_ACCEPT;
 553 #endif
 554
 555         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 556             !IS_PPPOE_IP(skb))
 557                 return NF_ACCEPT;
 558
 559         nf_bridge_pull_encap_header_rcsum(skb);
 560
 561         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 562                 goto inhdr_error;
 563
 564         iph = ip_hdr(skb);
 565         if (iph->ihl < 5 || iph->version != 4)
 566                 goto inhdr_error;
 567
 568         if (!pskb_may_pull(skb, 4 * iph->ihl))
 569                 goto inhdr_error;
 570
 571         iph = ip_hdr(skb);
 572         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 573                 goto inhdr_error;
 574
 575         len = ntohs(iph->tot_len);
 576         if (skb->len < len || len < 4 * iph->ihl)
 577                 goto inhdr_error;
 578
 579         pskb_trim_rcsum(skb, len);
 580
 581         nf_bridge_put(skb->nf_bridge);
 582         if (!nf_bridge_alloc(skb))
 583                 return NF_DROP;
 584         if (!setup_pre_routing(skb))
 585                 return NF_DROP;
 586         store_orig_dstaddr(skb);
 587
 588         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 589                 br_nf_pre_routing_finish);
 590
 591         return NF_STOLEN;
 592
 593 inhdr_error:
 594 //      IP_INC_STATS_BH(IpInHdrErrors);
 595 out:
 596         return NF_DROP;
 597 }
 598
 599
 600 /* PF_BRIDGE/LOCAL_IN ************************************************/
 601 /* The packet is locally destined, which requires a real
 602  * dst_entry, so detach the fake one.  On the way up, the
 603  * packet would pass through PRE_ROUTING again (which already
 604  * took place when the packet entered the bridge), but we
 605  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 606  * prevent this from happening. */
 607 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 608                                    const struct net_device *in,
 609                                    const struct net_device *out,
 610                                    int (*okfn)(struct sk_buff *))
 611 {
 612         struct rtable *rt = skb_rtable(skb);
 613
 614         if (rt && rt == bridge_parent_rtable(in))
 615                 skb_dst_drop(skb);
 616
 617         return NF_ACCEPT;
 618 }
 619
 620 /* PF_BRIDGE/FORWARD *************************************************/
 621 static int br_nf_forward_finish(struct sk_buff *skb)
 622 {
 623         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 624         struct net_device *in;
 625
 626         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 627                 in = nf_bridge->physindev;
 628                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 629                         skb->pkt_type = PACKET_OTHERHOST;
 630                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 631                 }
 632         } else {
 633                 in = *((struct net_device **)(skb->cb));
 634         }
 635         nf_bridge_push_encap_header(skb);
 636         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 637                        skb->dev, br_forward_finish, 1);
 638         return 0;
 639 }
 640
 641 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 642  * netfilter with indev and outdev set to the bridge device,
 643  * but we are still able to filter on the 'real' indev/outdev
 644  * because of the physdev module. For ARP, indev and outdev are the
 645  * bridge ports. */
 646 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 647                                      const struct net_device *in,
 648                                      const struct net_device *out,
 649                                      int (*okfn)(struct sk_buff *))
 650 {
 651         struct nf_bridge_info *nf_bridge;
 652         struct net_device *parent;
 653         u_int8_t pf;
 654
 655         if (!skb->nf_bridge)
 656                 return NF_ACCEPT;
 657
 658         /* Need exclusive nf_bridge_info since we might have multiple
 659          * different physoutdevs. */
 660         if (!nf_bridge_unshare(skb))
 661                 return NF_DROP;
 662
 663         parent = bridge_parent(out);
 664         if (!parent)
 665                 return NF_DROP;
 666
 667         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 668             IS_PPPOE_IP(skb))
 669                 pf = PF_INET;
 670         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 671                  IS_PPPOE_IPV6(skb))
 672                 pf = PF_INET6;
 673         else
 674                 return NF_ACCEPT;
 675
 676         nf_bridge_pull_encap_header(skb);
 677
 678         nf_bridge = skb->nf_bridge;
 679         if (skb->pkt_type == PACKET_OTHERHOST) {
 680                 skb->pkt_type = PACKET_HOST;
 681                 nf_bridge->mask |= BRNF_PKT_TYPE;
 682         }
 683
 684         /* The physdev module checks on this */
 685         nf_bridge->mask |= BRNF_BRIDGED;
 686         nf_bridge->physoutdev = skb->dev;
 687
 688         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 689                 br_nf_forward_finish);
 690
 691         return NF_STOLEN;
 692 }
 693
 694 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 695                                       const struct net_device *in,
 696                                       const struct net_device *out,
 697                                       int (*okfn)(struct sk_buff *))
 698 {
 699         struct net_device **d = (struct net_device **)(skb->cb);
 700
 701 #ifdef CONFIG_SYSCTL
 702         if (!brnf_call_arptables)
 703                 return NF_ACCEPT;
 704 #endif
 705
 706         if (skb->protocol != htons(ETH_P_ARP)) {
 707                 if (!IS_VLAN_ARP(skb))
 708                         return NF_ACCEPT;
 709                 nf_bridge_pull_encap_header(skb);
 710         }
 711
 712         if (arp_hdr(skb)->ar_pln != 4) {
 713                 if (IS_VLAN_ARP(skb))
 714                         nf_bridge_push_encap_header(skb);
 715                 return NF_ACCEPT;
 716         }
 717         *d = (struct net_device *)in;
 718         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 719                 (struct net_device *)out, br_nf_forward_finish);
 720
 721         return NF_STOLEN;
 722 }
 723
 724 /* PF_BRIDGE/LOCAL_OUT ***********************************************
 725  *
 726  * This function sees both locally originated IP packets and forwarded
 727  * IP packets (in both cases the destination device is a bridge
 728  * device). It also sees bridged-and-DNAT'ed packets.
 729  *
 730  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 731  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 732  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 733  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 734  * will be executed.
 735  */
 736 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 737                                     const struct net_device *in,
 738                                     const struct net_device *out,
 739                                     int (*okfn)(struct sk_buff *))
 740 {
 741         struct net_device *realindev;
 742         struct nf_bridge_info *nf_bridge;
 743
 744         if (!skb->nf_bridge)
 745                 return NF_ACCEPT;
 746
 747         /* Need exclusive nf_bridge_info since we might have multiple
 748          * different physoutdevs. */
 749         if (!nf_bridge_unshare(skb))
 750                 return NF_DROP;
 751
 752         nf_bridge = skb->nf_bridge;
 753         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
 754                 return NF_ACCEPT;
 755
 756         /* Bridged, take PF_BRIDGE/FORWARD.
 757          * (see big note in front of br_nf_pre_routing_finish) */
 758         nf_bridge->physoutdev = skb->dev;
 759         realindev = nf_bridge->physindev;
 760
 761         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 762                 skb->pkt_type = PACKET_OTHERHOST;
 763                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 764         }
 765         nf_bridge_push_encap_header(skb);
 766
 767         NF_HOOK(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
 768                 br_forward_finish);
 769         return NF_STOLEN;
 770 }
 771
 772 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 773 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 774 {
 775         if (skb->nfct != NULL &&
 776             (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb)) &&
 777             skb->len > skb->dev->mtu &&
 778             !skb_is_gso(skb))
 779                 return ip_fragment(skb, br_dev_queue_push_xmit);
 780         else
 781                 return br_dev_queue_push_xmit(skb);
 782 }
 783 #else
 784 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 785 {
 786         return br_dev_queue_push_xmit(skb);
 787 }
 788 #endif
 789
 790 /* PF_BRIDGE/POST_ROUTING ********************************************/
 791 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 792                                        const struct net_device *in,
 793                                        const struct net_device *out,
 794                                        int (*okfn)(struct sk_buff *))
 795 {
 796         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 797         struct net_device *realoutdev = bridge_parent(skb->dev);
 798         u_int8_t pf;
 799
 800         if (!nf_bridge)
 801                 return NF_ACCEPT;
 802
 803         if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
 804                 return NF_ACCEPT;
 805
 806         if (!realoutdev)
 807                 return NF_DROP;
 808
 809         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 810             IS_PPPOE_IP(skb))
 811                 pf = PF_INET;
 812         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 813                  IS_PPPOE_IPV6(skb))
 814                 pf = PF_INET6;
 815         else
 816                 return NF_ACCEPT;
 817
 818         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 819          * about the value of skb->pkt_type. */
 820         if (skb->pkt_type == PACKET_OTHERHOST) {
 821                 skb->pkt_type = PACKET_HOST;
 822                 nf_bridge->mask |= BRNF_PKT_TYPE;
 823         }
 824
 825         nf_bridge_pull_encap_header(skb);
 826         nf_bridge_save_header(skb);
 827
 828         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 829                 br_nf_dev_queue_xmit);
 830
 831         return NF_STOLEN;
 832 }
 833
 834 /* IP/SABOTAGE *****************************************************/
 835 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 836  * for the second time. */
 837 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 838                                    const struct net_device *in,
 839                                    const struct net_device *out,
 840                                    int (*okfn)(struct sk_buff *))
 841 {
 842         if (skb->nf_bridge &&
 843             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 844                 return NF_STOP;
 845         }
 846
 847         return NF_ACCEPT;
 848 }
 849
 850 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 851  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 852  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 853  * ip_refrag() can return NF_STOLEN. */
 854 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 855         {
 856                 .hook = br_nf_pre_routing,
 857                 .owner = THIS_MODULE,
 858                 .pf = PF_BRIDGE,
 859                 .hooknum = NF_BR_PRE_ROUTING,
 860                 .priority = NF_BR_PRI_BRNF,
 861         },
 862         {
 863                 .hook = br_nf_local_in,
 864                 .owner = THIS_MODULE,
 865                 .pf = PF_BRIDGE,
 866                 .hooknum = NF_BR_LOCAL_IN,
 867                 .priority = NF_BR_PRI_BRNF,
 868         },
 869         {
 870                 .hook = br_nf_forward_ip,
 871                 .owner = THIS_MODULE,
 872                 .pf = PF_BRIDGE,
 873                 .hooknum = NF_BR_FORWARD,
 874                 .priority = NF_BR_PRI_BRNF - 1,
 875         },
 876         {
 877                 .hook = br_nf_forward_arp,
 878                 .owner = THIS_MODULE,
 879                 .pf = PF_BRIDGE,
 880                 .hooknum = NF_BR_FORWARD,
 881                 .priority = NF_BR_PRI_BRNF,
 882         },
 883         {
 884                 .hook = br_nf_local_out,
 885                 .owner = THIS_MODULE,
 886                 .pf = PF_BRIDGE,
 887                 .hooknum = NF_BR_LOCAL_OUT,
 888                 .priority = NF_BR_PRI_FIRST,
 889         },
 890         {
 891                 .hook = br_nf_post_routing,
 892                 .owner = THIS_MODULE,
 893                 .pf = PF_BRIDGE,
 894                 .hooknum = NF_BR_POST_ROUTING,
 895                 .priority = NF_BR_PRI_LAST,
 896         },
 897         {
 898                 .hook = ip_sabotage_in,
 899                 .owner = THIS_MODULE,
 900                 .pf = PF_INET,
 901                 .hooknum = NF_INET_PRE_ROUTING,
 902                 .priority = NF_IP_PRI_FIRST,
 903         },
 904         {
 905                 .hook = ip_sabotage_in,
 906                 .owner = THIS_MODULE,
 907                 .pf = PF_INET6,
 908                 .hooknum = NF_INET_PRE_ROUTING,
 909                 .priority = NF_IP6_PRI_FIRST,
 910         },
 911 };
 912
 913 #ifdef CONFIG_SYSCTL
 914 static
 915 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 916                             void __user * buffer, size_t * lenp, loff_t * ppos)
 917 {
 918         int ret;
 919
 920         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 921
 922         if (write && *(int *)(ctl->data))
 923                 *(int *)(ctl->data) = 1;
 924         return ret;
 925 }
 926
 927 static ctl_table brnf_table[] = {
 928         {
 929                 .procname       = "bridge-nf-call-arptables",
 930                 .data           = &brnf_call_arptables,
 931                 .maxlen         = sizeof(int),
 932                 .mode           = 0644,
 933                 .proc_handler   = brnf_sysctl_call_tables,
 934         },
 935         {
 936                 .procname       = "bridge-nf-call-iptables",
 937                 .data           = &brnf_call_iptables,
 938                 .maxlen         = sizeof(int),
 939                 .mode           = 0644,
 940                 .proc_handler   = brnf_sysctl_call_tables,
 941         },
 942         {
 943                 .procname       = "bridge-nf-call-ip6tables",
 944                 .data           = &brnf_call_ip6tables,
 945                 .maxlen         = sizeof(int),
 946                 .mode           = 0644,
 947                 .proc_handler   = brnf_sysctl_call_tables,
 948         },
 949         {
 950                 .procname       = "bridge-nf-filter-vlan-tagged",
 951                 .data           = &brnf_filter_vlan_tagged,
 952                 .maxlen         = sizeof(int),
 953                 .mode           = 0644,
 954                 .proc_handler   = brnf_sysctl_call_tables,
 955         },
 956         {
 957                 .procname       = "bridge-nf-filter-pppoe-tagged",
 958                 .data           = &brnf_filter_pppoe_tagged,
 959                 .maxlen         = sizeof(int),
 960                 .mode           = 0644,
 961                 .proc_handler   = brnf_sysctl_call_tables,
 962         },
 963         { }
 964 };
 965
 966 static struct ctl_path brnf_path[] = {
 967         { .procname = "net", },
 968         { .procname = "bridge", },
 969         { }
 970 };
 971 #endif
 972
 973 int __init br_netfilter_init(void)
 974 {
 975         int ret;
 976
 977         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 978         if (ret < 0)
 979                 return ret;
 980 #ifdef CONFIG_SYSCTL
 981         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
 982         if (brnf_sysctl_header == NULL) {
 983                 printk(KERN_WARNING
 984                        "br_netfilter: can't register to sysctl.\n");
 985                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 986                 return -ENOMEM;
 987         }
 988 #endif
 989         printk(KERN_NOTICE "Bridge firewalling registered\n");
 990         return 0;
 991 }
 992
 993 void br_netfilter_fini(void)
 994 {
 995         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 996 #ifdef CONFIG_SYSCTL
 997         unregister_sysctl_table(brnf_sysctl_header);
 998 #endif
 999 }