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 (maintainer)   <bdschuym@pandora.be>
   8  *
   9  *      Changes:
  10  *      Apr 29 2003: physdev module support (bdschuym)
  11  *      Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
  12  *      Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
  13  *                   (bdschuym)
  14  *      Sep 01 2004: add IPv6 filtering (bdschuym)
  15  *
  16  *      This program is free software; you can redistribute it and/or
  17  *      modify it under the terms of the GNU General Public License
  18  *      as published by the Free Software Foundation; either version
  19  *      2 of the License, or (at your option) any later version.
  20  *
  21  *      Lennert dedicates this file to Kerstin Wurdinger.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/ip.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/if_ether.h>
  31 #include <linux/if_vlan.h>
  32 #include <linux/if_pppox.h>
  33 #include <linux/ppp_defs.h>
  34 #include <linux/netfilter_bridge.h>
  35 #include <linux/netfilter_ipv4.h>
  36 #include <linux/netfilter_ipv6.h>
  37 #include <linux/netfilter_arp.h>
  38 #include <linux/in_route.h>
  39 #include <linux/inetdevice.h>
  40
  41 #include <net/ip.h>
  42 #include <net/ipv6.h>
  43 #include <net/route.h>
  44
  45 #include <asm/uaccess.h>
  46 #include "br_private.h"
  47 #ifdef CONFIG_SYSCTL
  48 #include <linux/sysctl.h>
  49 #endif
  50
  51 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  52                                  (skb->nf_bridge->data))->daddr.ipv4)
  53 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  54 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  55
  56 #ifdef CONFIG_SYSCTL
  57 static struct ctl_table_header *brnf_sysctl_header;
  58 static int brnf_call_iptables __read_mostly = 1;
  59 static int brnf_call_ip6tables __read_mostly = 1;
  60 static int brnf_call_arptables __read_mostly = 1;
  61 static int brnf_filter_vlan_tagged __read_mostly = 1;
  62 static int brnf_filter_pppoe_tagged __read_mostly = 1;
  63 #else
  64 #define brnf_filter_vlan_tagged 1
  65 #define brnf_filter_pppoe_tagged 1
  66 #endif
  67
  68 static inline __be16 vlan_proto(const struct sk_buff *skb)
  69 {
  70         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  71 }
  72
  73 #define IS_VLAN_IP(skb) \
  74         (skb->protocol == htons(ETH_P_8021Q) && \
  75          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  76          brnf_filter_vlan_tagged)
  77
  78 #define IS_VLAN_IPV6(skb) \
  79         (skb->protocol == htons(ETH_P_8021Q) && \
  80          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  81          brnf_filter_vlan_tagged)
  82
  83 #define IS_VLAN_ARP(skb) \
  84         (skb->protocol == htons(ETH_P_8021Q) && \
  85          vlan_proto(skb) == htons(ETH_P_ARP) && \
  86          brnf_filter_vlan_tagged)
  87
  88 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  89 {
  90         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  91                             sizeof(struct pppoe_hdr)));
  92 }
  93
  94 #define IS_PPPOE_IP(skb) \
  95         (skb->protocol == htons(ETH_P_PPP_SES) && \
  96          pppoe_proto(skb) == htons(PPP_IP) && \
  97          brnf_filter_pppoe_tagged)
  98
  99 #define IS_PPPOE_IPV6(skb) \
 100         (skb->protocol == htons(ETH_P_PPP_SES) && \
 101          pppoe_proto(skb) == htons(PPP_IPV6) && \
 102          brnf_filter_pppoe_tagged)
 103
 104 /* We need these fake structures to make netfilter happy --
 105  * lots of places assume that skb->dst != NULL, which isn't
 106  * all that unreasonable.
 107  *
 108  * Currently, we fill in the PMTU entry because netfilter
 109  * refragmentation needs it, and the rt_flags entry because
 110  * ipt_REJECT needs it.  Future netfilter modules might
 111  * require us to fill additional fields. */
 112 static struct net_device __fake_net_device = {
 113         .hard_header_len        = ETH_HLEN,
 114 #ifdef CONFIG_NET_NS
 115         .nd_net                 = &init_net,
 116 #endif
 117 };
 118
 119 static struct rtable __fake_rtable = {
 120         .u = {
 121                 .dst = {
 122                         .__refcnt               = ATOMIC_INIT(1),
 123                         .dev                    = &__fake_net_device,
 124                         .path                   = &__fake_rtable.u.dst,
 125                         .metrics                = {[RTAX_MTU - 1] = 1500},
 126                         .flags                  = DST_NOXFRM,
 127                 }
 128         },
 129         .rt_flags       = 0,
 130 };
 131
 132 static inline struct net_device *bridge_parent(const struct net_device *dev)
 133 {
 134         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 135
 136         return port ? port->br->dev : NULL;
 137 }
 138
 139 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 140 {
 141         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 142         if (likely(skb->nf_bridge))
 143                 atomic_set(&(skb->nf_bridge->use), 1);
 144
 145         return skb->nf_bridge;
 146 }
 147
 148 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 149 {
 150         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 151
 152         if (atomic_read(&nf_bridge->use) > 1) {
 153                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 154
 155                 if (tmp) {
 156                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 157                         atomic_set(&tmp->use, 1);
 158                         nf_bridge_put(nf_bridge);
 159                 }
 160                 nf_bridge = tmp;
 161         }
 162         return nf_bridge;
 163 }
 164
 165 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 166 {
 167         unsigned int len = nf_bridge_encap_header_len(skb);
 168
 169         skb_push(skb, len);
 170         skb->network_header -= len;
 171 }
 172
 173 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 174 {
 175         unsigned int len = nf_bridge_encap_header_len(skb);
 176
 177         skb_pull(skb, len);
 178         skb->network_header += len;
 179 }
 180
 181 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 182 {
 183         unsigned int len = nf_bridge_encap_header_len(skb);
 184
 185         skb_pull_rcsum(skb, len);
 186         skb->network_header += len;
 187 }
 188
 189 static inline void nf_bridge_save_header(struct sk_buff *skb)
 190 {
 191         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 192
 193         skb_copy_from_linear_data_offset(skb, -header_size,
 194                                          skb->nf_bridge->data, header_size);
 195 }
 196
 197 /*
 198  * When forwarding bridge frames, we save a copy of the original
 199  * header before processing.
 200  */
 201 int nf_bridge_copy_header(struct sk_buff *skb)
 202 {
 203         int err;
 204         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 205
 206         err = skb_cow_head(skb, header_size);
 207         if (err)
 208                 return err;
 209
 210         skb_copy_to_linear_data_offset(skb, -header_size,
 211                                        skb->nf_bridge->data, header_size);
 212         __skb_push(skb, nf_bridge_encap_header_len(skb));
 213         return 0;
 214 }
 215
 216 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 217 /* Undo the changes made for ip6tables PREROUTING and continue the
 218  * bridge PRE_ROUTING hook. */
 219 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 220 {
 221         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 222
 223         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 224                 skb->pkt_type = PACKET_OTHERHOST;
 225                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 226         }
 227         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 228
 229         skb->rtable = &__fake_rtable;
 230         dst_hold(&__fake_rtable.u.dst);
 231
 232         skb->dev = nf_bridge->physindev;
 233         nf_bridge_push_encap_header(skb);
 234         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 235                        br_handle_frame_finish, 1);
 236
 237         return 0;
 238 }
 239
 240 static void __br_dnat_complain(void)
 241 {
 242         static unsigned long last_complaint;
 243
 244         if (jiffies - last_complaint >= 5 * HZ) {
 245                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 246                        "forwarding to be enabled\n");
 247                 last_complaint = jiffies;
 248         }
 249 }
 250
 251 /* This requires some explaining. If DNAT has taken place,
 252  * we will need to fix up the destination Ethernet address,
 253  * and this is a tricky process.
 254  *
 255  * There are two cases to consider:
 256  * 1. The packet was DNAT'ed to a device in the same bridge
 257  *    port group as it was received on. We can still bridge
 258  *    the packet.
 259  * 2. The packet was DNAT'ed to a different device, either
 260  *    a non-bridged device or another bridge port group.
 261  *    The packet will need to be routed.
 262  *
 263  * The correct way of distinguishing between these two cases is to
 264  * call ip_route_input() and to look at skb->dst->dev, which is
 265  * changed to the destination device if ip_route_input() succeeds.
 266  *
 267  * Let us first consider the case that ip_route_input() succeeds:
 268  *
 269  * If skb->dst->dev equals the logical bridge device the packet
 270  * came in on, we can consider this bridging. The packet is passed
 271  * through the neighbour output function to build a new destination
 272  * MAC address, which will make the packet enter br_nf_local_out()
 273  * not much later. In that function it is assured that the iptables
 274  * FORWARD chain is traversed for the packet.
 275  *
 276  * Otherwise, the packet is considered to be routed and we just
 277  * change the destination MAC address so that the packet will
 278  * later be passed up to the IP stack to be routed. For a redirected
 279  * packet, ip_route_input() will give back the localhost as output device,
 280  * which differs from the bridge device.
 281  *
 282  * Let us now consider the case that ip_route_input() fails:
 283  *
 284  * This can be because the destination address is martian, in which case
 285  * the packet will be dropped.
 286  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 287  * will fail, while __ip_route_output_key() will return success. The source
 288  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 289  * thinks we're handling a locally generated packet and won't care
 290  * if IP forwarding is allowed. We send a warning message to the users's
 291  * log telling her to put IP forwarding on.
 292  *
 293  * ip_route_input() will also fail if there is no route available.
 294  * In that case we just drop the packet.
 295  *
 296  * --Lennert, 20020411
 297  * --Bart, 20020416 (updated)
 298  * --Bart, 20021007 (updated)
 299  * --Bart, 20062711 (updated) */
 300 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 301 {
 302         if (skb->pkt_type == PACKET_OTHERHOST) {
 303                 skb->pkt_type = PACKET_HOST;
 304                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 305         }
 306         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 307
 308         skb->dev = bridge_parent(skb->dev);
 309         if (skb->dev) {
 310                 struct dst_entry *dst = skb->dst;
 311
 312                 nf_bridge_pull_encap_header(skb);
 313
 314                 if (dst->hh)
 315                         return neigh_hh_output(dst->hh, skb);
 316                 else if (dst->neighbour)
 317                         return dst->neighbour->output(skb);
 318         }
 319         kfree_skb(skb);
 320         return 0;
 321 }
 322
 323 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 324 {
 325         struct net_device *dev = skb->dev;
 326         struct iphdr *iph = ip_hdr(skb);
 327         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 328         int err;
 329
 330         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 331                 skb->pkt_type = PACKET_OTHERHOST;
 332                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 333         }
 334         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 335         if (dnat_took_place(skb)) {
 336                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 337                         struct rtable *rt;
 338                         struct flowi fl = {
 339                                 .nl_u = {
 340                                         .ip4_u = {
 341                                                  .daddr = iph->daddr,
 342                                                  .saddr = 0,
 343                                                  .tos = RT_TOS(iph->tos) },
 344                                 },
 345                                 .proto = 0,
 346                         };
 347                         struct in_device *in_dev = in_dev_get(dev);
 348
 349                         /* If err equals -EHOSTUNREACH the error is due to a
 350                          * martian destination or due to the fact that
 351                          * forwarding is disabled. For most martian packets,
 352                          * ip_route_output_key() will fail. It won't fail for 2 types of
 353                          * martian destinations: loopback destinations and destination
 354                          * 0.0.0.0. In both cases the packet will be dropped because the
 355                          * destination is the loopback device and not the bridge. */
 356                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 357                                 goto free_skb;
 358
 359                         if (!ip_route_output_key(&init_net, &rt, &fl)) {
 360                                 /* - Bridged-and-DNAT'ed traffic doesn't
 361                                  *   require ip_forwarding. */
 362                                 if (((struct dst_entry *)rt)->dev == dev) {
 363                                         skb->dst = (struct dst_entry *)rt;
 364                                         goto bridged_dnat;
 365                                 }
 366                                 /* we are sure that forwarding is disabled, so printing
 367                                  * this message is no problem. Note that the packet could
 368                                  * still have a martian destination address, in which case
 369                                  * the packet could be dropped even if forwarding were enabled */
 370                                 __br_dnat_complain();
 371                                 dst_release((struct dst_entry *)rt);
 372                         }
 373 free_skb:
 374                         kfree_skb(skb);
 375                         return 0;
 376                 } else {
 377                         if (skb->dst->dev == dev) {
 378 bridged_dnat:
 379                                 /* Tell br_nf_local_out this is a
 380                                  * bridged frame */
 381                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 382                                 skb->dev = nf_bridge->physindev;
 383                                 nf_bridge_push_encap_header(skb);
 384                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 385                                                skb, skb->dev, NULL,
 386                                                br_nf_pre_routing_finish_bridge,
 387                                                1);
 388                                 return 0;
 389                         }
 390                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 391                         skb->pkt_type = PACKET_HOST;
 392                 }
 393         } else {
 394                 skb->rtable = &__fake_rtable;
 395                 dst_hold(&__fake_rtable.u.dst);
 396         }
 397
 398         skb->dev = nf_bridge->physindev;
 399         nf_bridge_push_encap_header(skb);
 400         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 401                        br_handle_frame_finish, 1);
 402
 403         return 0;
 404 }
 405
 406 /* Some common code for IPv4/IPv6 */
 407 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 408 {
 409         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 410
 411         if (skb->pkt_type == PACKET_OTHERHOST) {
 412                 skb->pkt_type = PACKET_HOST;
 413                 nf_bridge->mask |= BRNF_PKT_TYPE;
 414         }
 415
 416         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 417         nf_bridge->physindev = skb->dev;
 418         skb->dev = bridge_parent(skb->dev);
 419
 420         return skb->dev;
 421 }
 422
 423 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 424 static int check_hbh_len(struct sk_buff *skb)
 425 {
 426         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 427         u32 pkt_len;
 428         const unsigned char *nh = skb_network_header(skb);
 429         int off = raw - nh;
 430         int len = (raw[1] + 1) << 3;
 431
 432         if ((raw + len) - skb->data > skb_headlen(skb))
 433                 goto bad;
 434
 435         off += 2;
 436         len -= 2;
 437
 438         while (len > 0) {
 439                 int optlen = nh[off + 1] + 2;
 440
 441                 switch (nh[off]) {
 442                 case IPV6_TLV_PAD0:
 443                         optlen = 1;
 444                         break;
 445
 446                 case IPV6_TLV_PADN:
 447                         break;
 448
 449                 case IPV6_TLV_JUMBO:
 450                         if (nh[off + 1] != 4 || (off & 3) != 2)
 451                                 goto bad;
 452                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 453                         if (pkt_len <= IPV6_MAXPLEN ||
 454                             ipv6_hdr(skb)->payload_len)
 455                                 goto bad;
 456                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 457                                 goto bad;
 458                         if (pskb_trim_rcsum(skb,
 459                                             pkt_len + sizeof(struct ipv6hdr)))
 460                                 goto bad;
 461                         nh = skb_network_header(skb);
 462                         break;
 463                 default:
 464                         if (optlen > len)
 465                                 goto bad;
 466                         break;
 467                 }
 468                 off += optlen;
 469                 len -= optlen;
 470         }
 471         if (len == 0)
 472                 return 0;
 473 bad:
 474         return -1;
 475
 476 }
 477
 478 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 479  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 480 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 481                                            struct sk_buff *skb,
 482                                            const struct net_device *in,
 483                                            const struct net_device *out,
 484                                            int (*okfn)(struct sk_buff *))
 485 {
 486         struct ipv6hdr *hdr;
 487         u32 pkt_len;
 488
 489         if (skb->len < sizeof(struct ipv6hdr))
 490                 goto inhdr_error;
 491
 492         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 493                 goto inhdr_error;
 494
 495         hdr = ipv6_hdr(skb);
 496
 497         if (hdr->version != 6)
 498                 goto inhdr_error;
 499
 500         pkt_len = ntohs(hdr->payload_len);
 501
 502         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 503                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 504                         goto inhdr_error;
 505                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 506                         goto inhdr_error;
 507         }
 508         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 509                 goto inhdr_error;
 510
 511         nf_bridge_put(skb->nf_bridge);
 512         if (!nf_bridge_alloc(skb))
 513                 return NF_DROP;
 514         if (!setup_pre_routing(skb))
 515                 return NF_DROP;
 516
 517         NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 518                 br_nf_pre_routing_finish_ipv6);
 519
 520         return NF_STOLEN;
 521
 522 inhdr_error:
 523         return NF_DROP;
 524 }
 525
 526 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 527  * Replicate the checks that IPv4 does on packet reception.
 528  * Set skb->dev to the bridge device (i.e. parent of the
 529  * receiving device) to make netfilter happy, the REDIRECT
 530  * target in particular.  Save the original destination IP
 531  * address to be able to detect DNAT afterwards. */
 532 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 533                                       const struct net_device *in,
 534                                       const struct net_device *out,
 535                                       int (*okfn)(struct sk_buff *))
 536 {
 537         struct iphdr *iph;
 538         __u32 len = nf_bridge_encap_header_len(skb);
 539
 540         if (unlikely(!pskb_may_pull(skb, len)))
 541                 goto out;
 542
 543         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 544             IS_PPPOE_IPV6(skb)) {
 545 #ifdef CONFIG_SYSCTL
 546                 if (!brnf_call_ip6tables)
 547                         return NF_ACCEPT;
 548 #endif
 549                 nf_bridge_pull_encap_header_rcsum(skb);
 550                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 551         }
 552 #ifdef CONFIG_SYSCTL
 553         if (!brnf_call_iptables)
 554                 return NF_ACCEPT;
 555 #endif
 556
 557         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 558             !IS_PPPOE_IP(skb))
 559                 return NF_ACCEPT;
 560
 561         nf_bridge_pull_encap_header_rcsum(skb);
 562
 563         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 564                 goto inhdr_error;
 565
 566         iph = ip_hdr(skb);
 567         if (iph->ihl < 5 || iph->version != 4)
 568                 goto inhdr_error;
 569
 570         if (!pskb_may_pull(skb, 4 * iph->ihl))
 571                 goto inhdr_error;
 572
 573         iph = ip_hdr(skb);
 574         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 575                 goto inhdr_error;
 576
 577         len = ntohs(iph->tot_len);
 578         if (skb->len < len || len < 4 * iph->ihl)
 579                 goto inhdr_error;
 580
 581         pskb_trim_rcsum(skb, len);
 582
 583         nf_bridge_put(skb->nf_bridge);
 584         if (!nf_bridge_alloc(skb))
 585                 return NF_DROP;
 586         if (!setup_pre_routing(skb))
 587                 return NF_DROP;
 588         store_orig_dstaddr(skb);
 589
 590         NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 591                 br_nf_pre_routing_finish);
 592
 593         return NF_STOLEN;
 594
 595 inhdr_error:
 596 //      IP_INC_STATS_BH(IpInHdrErrors);
 597 out:
 598         return NF_DROP;
 599 }
 600
 601
 602 /* PF_BRIDGE/LOCAL_IN ************************************************/
 603 /* The packet is locally destined, which requires a real
 604  * dst_entry, so detach the fake one.  On the way up, the
 605  * packet would pass through PRE_ROUTING again (which already
 606  * took place when the packet entered the bridge), but we
 607  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 608  * prevent this from happening. */
 609 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 610                                    const struct net_device *in,
 611                                    const struct net_device *out,
 612                                    int (*okfn)(struct sk_buff *))
 613 {
 614         if (skb->rtable == &__fake_rtable) {
 615                 dst_release(&__fake_rtable.u.dst);
 616                 skb->rtable = NULL;
 617         }
 618
 619         return NF_ACCEPT;
 620 }
 621
 622 /* PF_BRIDGE/FORWARD *************************************************/
 623 static int br_nf_forward_finish(struct sk_buff *skb)
 624 {
 625         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 626         struct net_device *in;
 627
 628         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 629                 in = nf_bridge->physindev;
 630                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 631                         skb->pkt_type = PACKET_OTHERHOST;
 632                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 633                 }
 634         } else {
 635                 in = *((struct net_device **)(skb->cb));
 636         }
 637         nf_bridge_push_encap_header(skb);
 638         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 639                        skb->dev, br_forward_finish, 1);
 640         return 0;
 641 }
 642
 643 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 644  * netfilter with indev and outdev set to the bridge device,
 645  * but we are still able to filter on the 'real' indev/outdev
 646  * because of the physdev module. For ARP, indev and outdev are the
 647  * bridge ports. */
 648 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 649                                      const struct net_device *in,
 650                                      const struct net_device *out,
 651                                      int (*okfn)(struct sk_buff *))
 652 {
 653         struct nf_bridge_info *nf_bridge;
 654         struct net_device *parent;
 655         int pf;
 656
 657         if (!skb->nf_bridge)
 658                 return NF_ACCEPT;
 659
 660         /* Need exclusive nf_bridge_info since we might have multiple
 661          * different physoutdevs. */
 662         if (!nf_bridge_unshare(skb))
 663                 return NF_DROP;
 664
 665         parent = bridge_parent(out);
 666         if (!parent)
 667                 return NF_DROP;
 668
 669         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 670             IS_PPPOE_IP(skb))
 671                 pf = PF_INET;
 672         else
 673                 pf = PF_INET6;
 674
 675         nf_bridge_pull_encap_header(skb);
 676
 677         nf_bridge = skb->nf_bridge;
 678         if (skb->pkt_type == PACKET_OTHERHOST) {
 679                 skb->pkt_type = PACKET_HOST;
 680                 nf_bridge->mask |= BRNF_PKT_TYPE;
 681         }
 682
 683         /* The physdev module checks on this */
 684         nf_bridge->mask |= BRNF_BRIDGED;
 685         nf_bridge->physoutdev = skb->dev;
 686
 687         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 688                 br_nf_forward_finish);
 689
 690         return NF_STOLEN;
 691 }
 692
 693 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 694                                       const struct net_device *in,
 695                                       const struct net_device *out,
 696                                       int (*okfn)(struct sk_buff *))
 697 {
 698         struct net_device **d = (struct net_device **)(skb->cb);
 699
 700 #ifdef CONFIG_SYSCTL
 701         if (!brnf_call_arptables)
 702                 return NF_ACCEPT;
 703 #endif
 704
 705         if (skb->protocol != htons(ETH_P_ARP)) {
 706                 if (!IS_VLAN_ARP(skb))
 707                         return NF_ACCEPT;
 708                 nf_bridge_pull_encap_header(skb);
 709         }
 710
 711         if (arp_hdr(skb)->ar_pln != 4) {
 712                 if (IS_VLAN_ARP(skb))
 713                         nf_bridge_push_encap_header(skb);
 714                 return NF_ACCEPT;
 715         }
 716         *d = (struct net_device *)in;
 717         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 718                 (struct net_device *)out, br_nf_forward_finish);
 719
 720         return NF_STOLEN;
 721 }
 722
 723 /* PF_BRIDGE/LOCAL_OUT ***********************************************
 724  *
 725  * This function sees both locally originated IP packets and forwarded
 726  * IP packets (in both cases the destination device is a bridge
 727  * device). It also sees bridged-and-DNAT'ed packets.
 728  *
 729  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 730  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 731  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 732  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 733  * will be executed.
 734  */
 735 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 736                                     const struct net_device *in,
 737                                     const struct net_device *out,
 738                                     int (*okfn)(struct sk_buff *))
 739 {
 740         struct net_device *realindev;
 741         struct nf_bridge_info *nf_bridge;
 742
 743         if (!skb->nf_bridge)
 744                 return NF_ACCEPT;
 745
 746         /* Need exclusive nf_bridge_info since we might have multiple
 747          * different physoutdevs. */
 748         if (!nf_bridge_unshare(skb))
 749                 return NF_DROP;
 750
 751         nf_bridge = skb->nf_bridge;
 752         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
 753                 return NF_ACCEPT;
 754
 755         /* Bridged, take PF_BRIDGE/FORWARD.
 756          * (see big note in front of br_nf_pre_routing_finish) */
 757         nf_bridge->physoutdev = skb->dev;
 758         realindev = nf_bridge->physindev;
 759
 760         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 761                 skb->pkt_type = PACKET_OTHERHOST;
 762                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 763         }
 764         nf_bridge_push_encap_header(skb);
 765
 766         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
 767                 br_forward_finish);
 768         return NF_STOLEN;
 769 }
 770
 771 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 772 {
 773         if (skb->protocol == htons(ETH_P_IP) &&
 774             skb->len > skb->dev->mtu &&
 775             !skb_is_gso(skb))
 776                 return ip_fragment(skb, br_dev_queue_push_xmit);
 777         else
 778                 return br_dev_queue_push_xmit(skb);
 779 }
 780
 781 /* PF_BRIDGE/POST_ROUTING ********************************************/
 782 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 783                                        const struct net_device *in,
 784                                        const struct net_device *out,
 785                                        int (*okfn)(struct sk_buff *))
 786 {
 787         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 788         struct net_device *realoutdev = bridge_parent(skb->dev);
 789         int pf;
 790
 791 #ifdef CONFIG_NETFILTER_DEBUG
 792         /* Be very paranoid. This probably won't happen anymore, but let's
 793          * keep the check just to be sure... */
 794         if (skb_mac_header(skb) < skb->head ||
 795             skb_mac_header(skb) + ETH_HLEN > skb->data) {
 796                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 797                        "bad mac.raw pointer.\n");
 798                 goto print_error;
 799         }
 800 #endif
 801
 802         if (!nf_bridge)
 803                 return NF_ACCEPT;
 804
 805         if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
 806                 return NF_ACCEPT;
 807
 808         if (!realoutdev)
 809                 return NF_DROP;
 810
 811         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 812             IS_PPPOE_IP(skb))
 813                 pf = PF_INET;
 814         else
 815                 pf = PF_INET6;
 816
 817 #ifdef CONFIG_NETFILTER_DEBUG
 818         if (skb->dst == NULL) {
 819                 printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
 820                 goto print_error;
 821         }
 822 #endif
 823
 824         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 825          * about the value of skb->pkt_type. */
 826         if (skb->pkt_type == PACKET_OTHERHOST) {
 827                 skb->pkt_type = PACKET_HOST;
 828                 nf_bridge->mask |= BRNF_PKT_TYPE;
 829         }
 830
 831         nf_bridge_pull_encap_header(skb);
 832         nf_bridge_save_header(skb);
 833
 834         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 835                 br_nf_dev_queue_xmit);
 836
 837         return NF_STOLEN;
 838
 839 #ifdef CONFIG_NETFILTER_DEBUG
 840 print_error:
 841         if (skb->dev != NULL) {
 842                 printk("[%s]", skb->dev->name);
 843                 if (realoutdev)
 844                         printk("[%s]", realoutdev->name);
 845         }
 846         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb),
 847                skb->data);
 848         dump_stack();
 849         return NF_ACCEPT;
 850 #endif
 851 }
 852
 853 /* IP/SABOTAGE *****************************************************/
 854 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 855  * for the second time. */
 856 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 857                                    const struct net_device *in,
 858                                    const struct net_device *out,
 859                                    int (*okfn)(struct sk_buff *))
 860 {
 861         if (skb->nf_bridge &&
 862             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 863                 return NF_STOP;
 864         }
 865
 866         return NF_ACCEPT;
 867 }
 868
 869 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 870  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 871  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 872  * ip_refrag() can return NF_STOLEN. */
 873 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 874         { .hook = br_nf_pre_routing,
 875           .owner = THIS_MODULE,
 876           .pf = PF_BRIDGE,
 877           .hooknum = NF_BR_PRE_ROUTING,
 878           .priority = NF_BR_PRI_BRNF, },
 879         { .hook = br_nf_local_in,
 880           .owner = THIS_MODULE,
 881           .pf = PF_BRIDGE,
 882           .hooknum = NF_BR_LOCAL_IN,
 883           .priority = NF_BR_PRI_BRNF, },
 884         { .hook = br_nf_forward_ip,
 885           .owner = THIS_MODULE,
 886           .pf = PF_BRIDGE,
 887           .hooknum = NF_BR_FORWARD,
 888           .priority = NF_BR_PRI_BRNF - 1, },
 889         { .hook = br_nf_forward_arp,
 890           .owner = THIS_MODULE,
 891           .pf = PF_BRIDGE,
 892           .hooknum = NF_BR_FORWARD,
 893           .priority = NF_BR_PRI_BRNF, },
 894         { .hook = br_nf_local_out,
 895           .owner = THIS_MODULE,
 896           .pf = PF_BRIDGE,
 897           .hooknum = NF_BR_LOCAL_OUT,
 898           .priority = NF_BR_PRI_FIRST, },
 899         { .hook = br_nf_post_routing,
 900           .owner = THIS_MODULE,
 901           .pf = PF_BRIDGE,
 902           .hooknum = NF_BR_POST_ROUTING,
 903           .priority = NF_BR_PRI_LAST, },
 904         { .hook = ip_sabotage_in,
 905           .owner = THIS_MODULE,
 906           .pf = PF_INET,
 907           .hooknum = NF_INET_PRE_ROUTING,
 908           .priority = NF_IP_PRI_FIRST, },
 909         { .hook = ip_sabotage_in,
 910           .owner = THIS_MODULE,
 911           .pf = PF_INET6,
 912           .hooknum = NF_INET_PRE_ROUTING,
 913           .priority = NF_IP6_PRI_FIRST, },
 914 };
 915
 916 #ifdef CONFIG_SYSCTL
 917 static
 918 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
 919                             void __user * buffer, size_t * lenp, loff_t * ppos)
 920 {
 921         int ret;
 922
 923         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 924
 925         if (write && *(int *)(ctl->data))
 926                 *(int *)(ctl->data) = 1;
 927         return ret;
 928 }
 929
 930 static ctl_table brnf_table[] = {
 931         {
 932                 .procname       = "bridge-nf-call-arptables",
 933                 .data           = &brnf_call_arptables,
 934                 .maxlen         = sizeof(int),
 935                 .mode           = 0644,
 936                 .proc_handler   = &brnf_sysctl_call_tables,
 937         },
 938         {
 939                 .procname       = "bridge-nf-call-iptables",
 940                 .data           = &brnf_call_iptables,
 941                 .maxlen         = sizeof(int),
 942                 .mode           = 0644,
 943                 .proc_handler   = &brnf_sysctl_call_tables,
 944         },
 945         {
 946                 .procname       = "bridge-nf-call-ip6tables",
 947                 .data           = &brnf_call_ip6tables,
 948                 .maxlen         = sizeof(int),
 949                 .mode           = 0644,
 950                 .proc_handler   = &brnf_sysctl_call_tables,
 951         },
 952         {
 953                 .procname       = "bridge-nf-filter-vlan-tagged",
 954                 .data           = &brnf_filter_vlan_tagged,
 955                 .maxlen         = sizeof(int),
 956                 .mode           = 0644,
 957                 .proc_handler   = &brnf_sysctl_call_tables,
 958         },
 959         {
 960                 .procname       = "bridge-nf-filter-pppoe-tagged",
 961                 .data           = &brnf_filter_pppoe_tagged,
 962                 .maxlen         = sizeof(int),
 963                 .mode           = 0644,
 964                 .proc_handler   = &brnf_sysctl_call_tables,
 965         },
 966         { .ctl_name = 0 }
 967 };
 968
 969 static struct ctl_path brnf_path[] = {
 970         { .procname = "net", .ctl_name = CTL_NET, },
 971         { .procname = "bridge", .ctl_name = NET_BRIDGE, },
 972         { }
 973 };
 974 #endif
 975
 976 int __init br_netfilter_init(void)
 977 {
 978         int ret;
 979
 980         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 981         if (ret < 0)
 982                 return ret;
 983 #ifdef CONFIG_SYSCTL
 984         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
 985         if (brnf_sysctl_header == NULL) {
 986                 printk(KERN_WARNING
 987                        "br_netfilter: can't register to sysctl.\n");
 988                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 989                 return -ENOMEM;
 990         }
 991 #endif
 992         printk(KERN_NOTICE "Bridge firewalling registered\n");
 993         return 0;
 994 }
 995
 996 void br_netfilter_fini(void)
 997 {
 998         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 999 #ifdef CONFIG_SYSCTL
1000         unregister_sysctl_table(brnf_sysctl_header);
1001 #endif
1002 }