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/netfilter_bridge.h>
  33 #include <linux/netfilter_ipv4.h>
  34 #include <linux/netfilter_ipv6.h>
  35 #include <linux/netfilter_arp.h>
  36 #include <linux/in_route.h>
  37
  38 #include <net/ip.h>
  39 #include <net/ipv6.h>
  40 #include <net/route.h>
  41
  42 #include <asm/uaccess.h>
  43 #include <asm/checksum.h>
  44 #include "br_private.h"
  45 #ifdef CONFIG_SYSCTL
  46 #include <linux/sysctl.h>
  47 #endif
  48
  49 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  50                                  (skb->nf_bridge->data))->daddr.ipv4)
  51 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = (skb)->nh.iph->daddr)
  52 #define dnat_took_place(skb)     (skb_origaddr(skb) != (skb)->nh.iph->daddr)
  53
  54 #ifdef CONFIG_SYSCTL
  55 static struct ctl_table_header *brnf_sysctl_header;
  56 static int brnf_call_iptables = 1;
  57 static int brnf_call_ip6tables = 1;
  58 static int brnf_call_arptables = 1;
  59 static int brnf_filter_vlan_tagged = 1;
  60 #else
  61 #define brnf_filter_vlan_tagged 1
  62 #endif
  63
  64 #define IS_VLAN_IP (skb->protocol == __constant_htons(ETH_P_8021Q) &&    \
  65         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IP) &&  \
  66         brnf_filter_vlan_tagged)
  67 #define IS_VLAN_IPV6 (skb->protocol == __constant_htons(ETH_P_8021Q) &&    \
  68         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IPV6) &&  \
  69         brnf_filter_vlan_tagged)
  70 #define IS_VLAN_ARP (skb->protocol == __constant_htons(ETH_P_8021Q) &&   \
  71         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_ARP) && \
  72         brnf_filter_vlan_tagged)
  73
  74 /* We need these fake structures to make netfilter happy --
  75  * lots of places assume that skb->dst != NULL, which isn't
  76  * all that unreasonable.
  77  *
  78  * Currently, we fill in the PMTU entry because netfilter
  79  * refragmentation needs it, and the rt_flags entry because
  80  * ipt_REJECT needs it.  Future netfilter modules might
  81  * require us to fill additional fields. */
  82 static struct net_device __fake_net_device = {
  83         .hard_header_len        = ETH_HLEN
  84 };
  85
  86 static struct rtable __fake_rtable = {
  87         .u = {
  88                 .dst = {
  89                         .__refcnt               = ATOMIC_INIT(1),
  90                         .dev                    = &__fake_net_device,
  91                         .path                   = &__fake_rtable.u.dst,
  92                         .metrics                = {[RTAX_MTU - 1] = 1500},
  93                 }
  94         },
  95         .rt_flags       = 0,
  96 };
  97
  98 static inline struct net_device *bridge_parent(const struct net_device *dev)
  99 {
 100         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 101
 102         return port ? port->br->dev : NULL;
 103 }
 104
 105 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 106 /* Undo the changes made for ip6tables PREROUTING and continue the
 107  * bridge PRE_ROUTING hook. */
 108 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 109 {
 110         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 111
 112         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 113                 skb->pkt_type = PACKET_OTHERHOST;
 114                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 115         }
 116         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 117
 118         skb->dst = (struct dst_entry *)&__fake_rtable;
 119         dst_hold(skb->dst);
 120
 121         skb->dev = nf_bridge->physindev;
 122         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 123                 skb_push(skb, VLAN_HLEN);
 124                 skb->nh.raw -= VLAN_HLEN;
 125         }
 126         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 127                        br_handle_frame_finish, 1);
 128
 129         return 0;
 130 }
 131
 132 static void __br_dnat_complain(void)
 133 {
 134         static unsigned long last_complaint;
 135
 136         if (jiffies - last_complaint >= 5 * HZ) {
 137                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 138                         "forwarding to be enabled\n");
 139                 last_complaint = jiffies;
 140         }
 141 }
 142
 143 /* This requires some explaining. If DNAT has taken place,
 144  * we will need to fix up the destination Ethernet address,
 145  * and this is a tricky process.
 146  *
 147  * There are two cases to consider:
 148  * 1. The packet was DNAT'ed to a device in the same bridge
 149  *    port group as it was received on. We can still bridge
 150  *    the packet.
 151  * 2. The packet was DNAT'ed to a different device, either
 152  *    a non-bridged device or another bridge port group.
 153  *    The packet will need to be routed.
 154  *
 155  * The correct way of distinguishing between these two cases is to
 156  * call ip_route_input() and to look at skb->dst->dev, which is
 157  * changed to the destination device if ip_route_input() succeeds.
 158  *
 159  * Let us first consider the case that ip_route_input() succeeds:
 160  *
 161  * If skb->dst->dev equals the logical bridge device the packet
 162  * came in on, we can consider this bridging. We then call
 163  * skb->dst->output() which will make the packet enter br_nf_local_out()
 164  * not much later. In that function it is assured that the iptables
 165  * FORWARD chain is traversed for the packet.
 166  *
 167  * Otherwise, the packet is considered to be routed and we just
 168  * change the destination MAC address so that the packet will
 169  * later be passed up to the IP stack to be routed.
 170  *
 171  * Let us now consider the case that ip_route_input() fails:
 172  *
 173  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 174  * will fail, while __ip_route_output_key() will return success. The source
 175  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 176  * thinks we're handling a locally generated packet and won't care
 177  * if IP forwarding is allowed. We send a warning message to the users's
 178  * log telling her to put IP forwarding on.
 179  *
 180  * ip_route_input() will also fail if there is no route available.
 181  * In that case we just drop the packet.
 182  *
 183  * --Lennert, 20020411
 184  * --Bart, 20020416 (updated)
 185  * --Bart, 20021007 (updated) */
 186 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 187 {
 188         if (skb->pkt_type == PACKET_OTHERHOST) {
 189                 skb->pkt_type = PACKET_HOST;
 190                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 191         }
 192         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 193
 194         skb->dev = bridge_parent(skb->dev);
 195         if (!skb->dev)
 196                 kfree_skb(skb);
 197         else {
 198                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 199                         skb_pull(skb, VLAN_HLEN);
 200                         skb->nh.raw += VLAN_HLEN;
 201                 }
 202                 skb->dst->output(skb);
 203         }
 204         return 0;
 205 }
 206
 207 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 208 {
 209         struct net_device *dev = skb->dev;
 210         struct iphdr *iph = skb->nh.iph;
 211         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 212
 213         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 214                 skb->pkt_type = PACKET_OTHERHOST;
 215                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 216         }
 217         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 218
 219         if (dnat_took_place(skb)) {
 220                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
 221                     dev)) {
 222                         struct rtable *rt;
 223                         struct flowi fl = { .nl_u =
 224                         { .ip4_u = { .daddr = iph->daddr, .saddr = 0 ,
 225                                      .tos = RT_TOS(iph->tos)} }, .proto = 0};
 226
 227                         if (!ip_route_output_key(&rt, &fl)) {
 228                                 /* - Bridged-and-DNAT'ed traffic doesn't
 229                                  *   require ip_forwarding.
 230                                  * - Deal with redirected traffic. */
 231                                 if (((struct dst_entry *)rt)->dev == dev ||
 232                                     rt->rt_type == RTN_LOCAL) {
 233                                         skb->dst = (struct dst_entry *)rt;
 234                                         goto bridged_dnat;
 235                                 }
 236                                 __br_dnat_complain();
 237                                 dst_release((struct dst_entry *)rt);
 238                         }
 239                         kfree_skb(skb);
 240                         return 0;
 241                 } else {
 242                         if (skb->dst->dev == dev) {
 243 bridged_dnat:
 244                                 /* Tell br_nf_local_out this is a
 245                                  * bridged frame */
 246                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 247                                 skb->dev = nf_bridge->physindev;
 248                                 if (skb->protocol ==
 249                                     __constant_htons(ETH_P_8021Q)) {
 250                                         skb_push(skb, VLAN_HLEN);
 251                                         skb->nh.raw -= VLAN_HLEN;
 252                                 }
 253                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 254                                                skb, skb->dev, NULL,
 255                                                br_nf_pre_routing_finish_bridge,
 256                                                1);
 257                                 return 0;
 258                         }
 259                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr,
 260                                ETH_ALEN);
 261                         skb->pkt_type = PACKET_HOST;
 262                 }
 263         } else {
 264                 skb->dst = (struct dst_entry *)&__fake_rtable;
 265                 dst_hold(skb->dst);
 266         }
 267
 268         skb->dev = nf_bridge->physindev;
 269         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 270                 skb_push(skb, VLAN_HLEN);
 271                 skb->nh.raw -= VLAN_HLEN;
 272         }
 273         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 274                        br_handle_frame_finish, 1);
 275
 276         return 0;
 277 }
 278
 279 /* Some common code for IPv4/IPv6 */
 280 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 281 {
 282         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 283
 284         if (skb->pkt_type == PACKET_OTHERHOST) {
 285                 skb->pkt_type = PACKET_HOST;
 286                 nf_bridge->mask |= BRNF_PKT_TYPE;
 287         }
 288
 289         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 290         nf_bridge->physindev = skb->dev;
 291         skb->dev = bridge_parent(skb->dev);
 292
 293         return skb->dev;
 294 }
 295
 296 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 297 static int check_hbh_len(struct sk_buff *skb)
 298 {
 299         unsigned char *raw = (u8*)(skb->nh.ipv6h+1);
 300         u32 pkt_len;
 301         int off = raw - skb->nh.raw;
 302         int len = (raw[1]+1)<<3;
 303
 304         if ((raw + len) - skb->data > skb_headlen(skb))
 305                 goto bad;
 306
 307         off += 2;
 308         len -= 2;
 309
 310         while (len > 0) {
 311                 int optlen = skb->nh.raw[off+1]+2;
 312
 313                 switch (skb->nh.raw[off]) {
 314                 case IPV6_TLV_PAD0:
 315                         optlen = 1;
 316                         break;
 317
 318                 case IPV6_TLV_PADN:
 319                         break;
 320
 321                 case IPV6_TLV_JUMBO:
 322                         if (skb->nh.raw[off+1] != 4 || (off&3) != 2)
 323                                 goto bad;
 324                         pkt_len = ntohl(*(u32*)(skb->nh.raw+off+2));
 325                         if (pkt_len <= IPV6_MAXPLEN ||
 326                             skb->nh.ipv6h->payload_len)
 327                                 goto bad;
 328                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 329                                 goto bad;
 330                         if (pskb_trim_rcsum(skb,
 331                             pkt_len+sizeof(struct ipv6hdr)))
 332                                 goto bad;
 333                         break;
 334                 default:
 335                         if (optlen > len)
 336                                 goto bad;
 337                         break;
 338                 }
 339                 off += optlen;
 340                 len -= optlen;
 341         }
 342         if (len == 0)
 343                 return 0;
 344 bad:
 345         return -1;
 346
 347 }
 348
 349 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 350  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 351 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 352    struct sk_buff *skb, const struct net_device *in,
 353    const struct net_device *out, int (*okfn)(struct sk_buff *))
 354 {
 355         struct ipv6hdr *hdr;
 356         u32 pkt_len;
 357         struct nf_bridge_info *nf_bridge;
 358
 359         if (skb->len < sizeof(struct ipv6hdr))
 360                 goto inhdr_error;
 361
 362         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 363                 goto inhdr_error;
 364
 365         hdr = skb->nh.ipv6h;
 366
 367         if (hdr->version != 6)
 368                 goto inhdr_error;
 369
 370         pkt_len = ntohs(hdr->payload_len);
 371
 372         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 373                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 374                         goto inhdr_error;
 375                 if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
 376                         if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr)))
 377                                 goto inhdr_error;
 378                         if (skb->ip_summed == CHECKSUM_HW)
 379                                 skb->ip_summed = CHECKSUM_NONE;
 380                 }
 381         }
 382         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 383                         goto inhdr_error;
 384
 385         nf_bridge_put(skb->nf_bridge);
 386         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 387                 return NF_DROP;
 388         if (!setup_pre_routing(skb))
 389                 return NF_DROP;
 390
 391         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 392                 br_nf_pre_routing_finish_ipv6);
 393
 394         return NF_STOLEN;
 395
 396 inhdr_error:
 397         return NF_DROP;
 398 }
 399
 400 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 401  * Replicate the checks that IPv4 does on packet reception.
 402  * Set skb->dev to the bridge device (i.e. parent of the
 403  * receiving device) to make netfilter happy, the REDIRECT
 404  * target in particular.  Save the original destination IP
 405  * address to be able to detect DNAT afterwards. */
 406 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 407                                       const struct net_device *in,
 408                                       const struct net_device *out,
 409                                       int (*okfn)(struct sk_buff *))
 410 {
 411         struct iphdr *iph;
 412         __u32 len;
 413         struct sk_buff *skb = *pskb;
 414         struct nf_bridge_info *nf_bridge;
 415         struct vlan_ethhdr *hdr = vlan_eth_hdr(*pskb);
 416
 417         if (skb->protocol == __constant_htons(ETH_P_IPV6) || IS_VLAN_IPV6) {
 418 #ifdef CONFIG_SYSCTL
 419                 if (!brnf_call_ip6tables)
 420                         return NF_ACCEPT;
 421 #endif
 422                 if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 423                         goto out;
 424
 425                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 426                         u8 *vhdr = skb->data;
 427                         skb_pull(skb, VLAN_HLEN);
 428                         skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
 429                         skb->nh.raw += VLAN_HLEN;
 430                 }
 431                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 432         }
 433 #ifdef CONFIG_SYSCTL
 434         if (!brnf_call_iptables)
 435                 return NF_ACCEPT;
 436 #endif
 437
 438         if (skb->protocol != __constant_htons(ETH_P_IP) && !IS_VLAN_IP)
 439                 return NF_ACCEPT;
 440
 441         if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 442                 goto out;
 443
 444         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 445                 u8 *vhdr = skb->data;
 446                 skb_pull(skb, VLAN_HLEN);
 447                 skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
 448                 skb->nh.raw += VLAN_HLEN;
 449         }
 450
 451         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 452                 goto inhdr_error;
 453
 454         iph = skb->nh.iph;
 455         if (iph->ihl < 5 || iph->version != 4)
 456                 goto inhdr_error;
 457
 458         if (!pskb_may_pull(skb, 4*iph->ihl))
 459                 goto inhdr_error;
 460
 461         iph = skb->nh.iph;
 462         if (ip_fast_csum((__u8 *)iph, iph->ihl) != 0)
 463                 goto inhdr_error;
 464
 465         len = ntohs(iph->tot_len);
 466         if (skb->len < len || len < 4*iph->ihl)
 467                 goto inhdr_error;
 468
 469         if (skb->len > len) {
 470                 __pskb_trim(skb, len);
 471                 if (skb->ip_summed == CHECKSUM_HW)
 472                         skb->ip_summed = CHECKSUM_NONE;
 473         }
 474
 475         nf_bridge_put(skb->nf_bridge);
 476         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 477                 return NF_DROP;
 478         if (!setup_pre_routing(skb))
 479                 return NF_DROP;
 480         store_orig_dstaddr(skb);
 481
 482         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 483                 br_nf_pre_routing_finish);
 484
 485         return NF_STOLEN;
 486
 487 inhdr_error:
 488 //      IP_INC_STATS_BH(IpInHdrErrors);
 489 out:
 490         return NF_DROP;
 491 }
 492
 493
 494 /* PF_BRIDGE/LOCAL_IN ************************************************/
 495 /* The packet is locally destined, which requires a real
 496  * dst_entry, so detach the fake one.  On the way up, the
 497  * packet would pass through PRE_ROUTING again (which already
 498  * took place when the packet entered the bridge), but we
 499  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 500  * prevent this from happening. */
 501 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
 502    const struct net_device *in, const struct net_device *out,
 503    int (*okfn)(struct sk_buff *))
 504 {
 505         struct sk_buff *skb = *pskb;
 506
 507         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 508                 dst_release(skb->dst);
 509                 skb->dst = NULL;
 510         }
 511
 512         return NF_ACCEPT;
 513 }
 514
 515
 516 /* PF_BRIDGE/FORWARD *************************************************/
 517 static int br_nf_forward_finish(struct sk_buff *skb)
 518 {
 519         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 520         struct net_device *in;
 521         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 522
 523         if (skb->protocol != __constant_htons(ETH_P_ARP) && !IS_VLAN_ARP) {
 524                 in = nf_bridge->physindev;
 525                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 526                         skb->pkt_type = PACKET_OTHERHOST;
 527                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 528                 }
 529         } else {
 530                 in = *((struct net_device **)(skb->cb));
 531         }
 532         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 533                 skb_push(skb, VLAN_HLEN);
 534                 skb->nh.raw -= VLAN_HLEN;
 535         }
 536         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 537                         skb->dev, br_forward_finish, 1);
 538         return 0;
 539 }
 540
 541 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 542  * netfilter with indev and outdev set to the bridge device,
 543  * but we are still able to filter on the 'real' indev/outdev
 544  * because of the physdev module. For ARP, indev and outdev are the
 545  * bridge ports. */
 546 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
 547    const struct net_device *in, const struct net_device *out,
 548    int (*okfn)(struct sk_buff *))
 549 {
 550         struct sk_buff *skb = *pskb;
 551         struct nf_bridge_info *nf_bridge;
 552         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 553         struct net_device *parent;
 554         int pf;
 555
 556         if (!skb->nf_bridge)
 557                 return NF_ACCEPT;
 558
 559         parent = bridge_parent(out);
 560         if (!parent)
 561                 return NF_DROP;
 562
 563         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 564                 pf = PF_INET;
 565         else
 566                 pf = PF_INET6;
 567
 568         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 569                 skb_pull(*pskb, VLAN_HLEN);
 570                 (*pskb)->nh.raw += VLAN_HLEN;
 571         }
 572
 573         nf_bridge = skb->nf_bridge;
 574         if (skb->pkt_type == PACKET_OTHERHOST) {
 575                 skb->pkt_type = PACKET_HOST;
 576                 nf_bridge->mask |= BRNF_PKT_TYPE;
 577         }
 578
 579         /* The physdev module checks on this */
 580         nf_bridge->mask |= BRNF_BRIDGED;
 581         nf_bridge->physoutdev = skb->dev;
 582
 583         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
 584                 br_nf_forward_finish);
 585
 586         return NF_STOLEN;
 587 }
 588
 589 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
 590    const struct net_device *in, const struct net_device *out,
 591    int (*okfn)(struct sk_buff *))
 592 {
 593         struct sk_buff *skb = *pskb;
 594         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 595         struct net_device **d = (struct net_device **)(skb->cb);
 596
 597 #ifdef CONFIG_SYSCTL
 598         if (!brnf_call_arptables)
 599                 return NF_ACCEPT;
 600 #endif
 601
 602         if (skb->protocol != __constant_htons(ETH_P_ARP)) {
 603                 if (!IS_VLAN_ARP)
 604                         return NF_ACCEPT;
 605                 skb_pull(*pskb, VLAN_HLEN);
 606                 (*pskb)->nh.raw += VLAN_HLEN;
 607         }
 608
 609         if (skb->nh.arph->ar_pln != 4) {
 610                 if (IS_VLAN_ARP) {
 611                         skb_push(*pskb, VLAN_HLEN);
 612                         (*pskb)->nh.raw -= VLAN_HLEN;
 613                 }
 614                 return NF_ACCEPT;
 615         }
 616         *d = (struct net_device *)in;
 617         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 618                 (struct net_device *)out, br_nf_forward_finish);
 619
 620         return NF_STOLEN;
 621 }
 622
 623
 624 /* PF_BRIDGE/LOCAL_OUT ***********************************************/
 625 static int br_nf_local_out_finish(struct sk_buff *skb)
 626 {
 627         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 628                 skb_push(skb, VLAN_HLEN);
 629                 skb->nh.raw -= VLAN_HLEN;
 630         }
 631
 632         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 633                         br_forward_finish, NF_BR_PRI_FIRST + 1);
 634
 635         return 0;
 636 }
 637
 638 /* This function sees both locally originated IP packets and forwarded
 639  * IP packets (in both cases the destination device is a bridge
 640  * device). It also sees bridged-and-DNAT'ed packets.
 641  * To be able to filter on the physical bridge devices (with the physdev
 642  * module), we steal packets destined to a bridge device away from the
 643  * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
 644  * when we have determined the real output device. This is done in here.
 645  *
 646  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 647  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 648  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 649  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 650  * will be executed.
 651  * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
 652  * this packet before, and so the packet was locally originated. We fake
 653  * the PF_INET/LOCAL_OUT hook.
 654  * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
 655  * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
 656  * even routed packets that didn't arrive on a bridge interface have their
 657  * nf_bridge->physindev set. */
 658 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
 659    const struct net_device *in, const struct net_device *out,
 660    int (*okfn)(struct sk_buff *))
 661 {
 662         struct net_device *realindev, *realoutdev;
 663         struct sk_buff *skb = *pskb;
 664         struct nf_bridge_info *nf_bridge;
 665         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 666         int pf;
 667
 668         if (!skb->nf_bridge)
 669                 return NF_ACCEPT;
 670
 671         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 672                 pf = PF_INET;
 673         else
 674                 pf = PF_INET6;
 675
 676 #ifdef CONFIG_NETFILTER_DEBUG
 677         /* Sometimes we get packets with NULL ->dst here (for example,
 678          * running a dhcp client daemon triggers this). This should now
 679          * be fixed, but let's keep the check around. */
 680         if (skb->dst == NULL) {
 681                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 682                 return NF_ACCEPT;
 683         }
 684 #endif
 685
 686         nf_bridge = skb->nf_bridge;
 687         nf_bridge->physoutdev = skb->dev;
 688         realindev = nf_bridge->physindev;
 689
 690         /* Bridged, take PF_BRIDGE/FORWARD.
 691          * (see big note in front of br_nf_pre_routing_finish) */
 692         if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
 693                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 694                         skb->pkt_type = PACKET_OTHERHOST;
 695                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 696                 }
 697                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 698                         skb_push(skb, VLAN_HLEN);
 699                         skb->nh.raw -= VLAN_HLEN;
 700                 }
 701
 702                 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
 703                         skb->dev, br_forward_finish);
 704                 goto out;
 705         }
 706         realoutdev = bridge_parent(skb->dev);
 707         if (!realoutdev)
 708                 return NF_DROP;
 709
 710 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 711         /* iptables should match -o br0.x */
 712         if (nf_bridge->netoutdev)
 713                 realoutdev = nf_bridge->netoutdev;
 714 #endif
 715         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 716                 skb_pull(skb, VLAN_HLEN);
 717                 (*pskb)->nh.raw += VLAN_HLEN;
 718         }
 719         /* IP forwarded traffic has a physindev, locally
 720          * generated traffic hasn't. */
 721         if (realindev != NULL) {
 722                 if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) ) {
 723                         struct net_device *parent = bridge_parent(realindev);
 724                         if (parent)
 725                                 realindev = parent;
 726                 }
 727
 728                 NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
 729                                realoutdev, br_nf_local_out_finish,
 730                                NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
 731         } else {
 732                 NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
 733                                realoutdev, br_nf_local_out_finish,
 734                                NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
 735         }
 736
 737 out:
 738         return NF_STOLEN;
 739 }
 740
 741
 742 /* PF_BRIDGE/POST_ROUTING ********************************************/
 743 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
 744    const struct net_device *in, const struct net_device *out,
 745    int (*okfn)(struct sk_buff *))
 746 {
 747         struct sk_buff *skb = *pskb;
 748         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
 749         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 750         struct net_device *realoutdev = bridge_parent(skb->dev);
 751         int pf;
 752
 753 #ifdef CONFIG_NETFILTER_DEBUG
 754         /* Be very paranoid. This probably won't happen anymore, but let's
 755          * keep the check just to be sure... */
 756         if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
 757                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 758                                  "bad mac.raw pointer.");
 759                 goto print_error;
 760         }
 761 #endif
 762
 763         if (!nf_bridge)
 764                 return NF_ACCEPT;
 765
 766         if (!realoutdev)
 767                 return NF_DROP;
 768
 769         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 770                 pf = PF_INET;
 771         else
 772                 pf = PF_INET6;
 773
 774 #ifdef CONFIG_NETFILTER_DEBUG
 775         if (skb->dst == NULL) {
 776                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 777                 goto print_error;
 778         }
 779 #endif
 780
 781         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 782          * about the value of skb->pkt_type. */
 783         if (skb->pkt_type == PACKET_OTHERHOST) {
 784                 skb->pkt_type = PACKET_HOST;
 785                 nf_bridge->mask |= BRNF_PKT_TYPE;
 786         }
 787
 788         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 789                 skb_pull(skb, VLAN_HLEN);
 790                 skb->nh.raw += VLAN_HLEN;
 791         }
 792
 793         nf_bridge_save_header(skb);
 794
 795 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 796         if (nf_bridge->netoutdev)
 797                 realoutdev = nf_bridge->netoutdev;
 798 #endif
 799         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
 800                 br_dev_queue_push_xmit);
 801
 802         return NF_STOLEN;
 803
 804 #ifdef CONFIG_NETFILTER_DEBUG
 805 print_error:
 806         if (skb->dev != NULL) {
 807                 printk("[%s]", skb->dev->name);
 808                 if (has_bridge_parent(skb->dev))
 809                         printk("[%s]", bridge_parent(skb->dev)->name);
 810         }
 811         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
 812                                               skb->data);
 813         return NF_ACCEPT;
 814 #endif
 815 }
 816
 817
 818 /* IP/SABOTAGE *****************************************************/
 819 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 820  * for the second time. */
 821 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
 822    const struct net_device *in, const struct net_device *out,
 823    int (*okfn)(struct sk_buff *))
 824 {
 825         if ((*pskb)->nf_bridge &&
 826             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 827                 return NF_STOP;
 828         }
 829
 830         return NF_ACCEPT;
 831 }
 832
 833 /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
 834  * and PF_INET(6)/POST_ROUTING until we have done the forwarding
 835  * decision in the bridge code and have determined nf_bridge->physoutdev. */
 836 static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 837    const struct net_device *in, const struct net_device *out,
 838    int (*okfn)(struct sk_buff *))
 839 {
 840         struct sk_buff *skb = *pskb;
 841
 842         if ((out->hard_start_xmit == br_dev_xmit &&
 843             okfn != br_nf_forward_finish &&
 844             okfn != br_nf_local_out_finish &&
 845             okfn != br_dev_queue_push_xmit)
 846 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 847             || ((out->priv_flags & IFF_802_1Q_VLAN) &&
 848             VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
 849 #endif
 850             ) {
 851                 struct nf_bridge_info *nf_bridge;
 852
 853                 if (!skb->nf_bridge) {
 854 #ifdef CONFIG_SYSCTL
 855                         /* This code is executed while in the IP(v6) stack,
 856                            the version should be 4 or 6. We can't use
 857                            skb->protocol because that isn't set on
 858                            PF_INET(6)/LOCAL_OUT. */
 859                         struct iphdr *ip = skb->nh.iph;
 860
 861                         if (ip->version == 4 && !brnf_call_iptables)
 862                                 return NF_ACCEPT;
 863                         else if (ip->version == 6 && !brnf_call_ip6tables)
 864                                 return NF_ACCEPT;
 865 #endif
 866                         if (hook == NF_IP_POST_ROUTING)
 867                                 return NF_ACCEPT;
 868                         if (!nf_bridge_alloc(skb))
 869                                 return NF_DROP;
 870                 }
 871
 872                 nf_bridge = skb->nf_bridge;
 873
 874                 /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
 875                  * will need the indev then. For a brouter, the real indev
 876                  * can be a bridge port, so we make sure br_nf_local_out()
 877                  * doesn't use the bridge parent of the indev by using
 878                  * the BRNF_DONT_TAKE_PARENT mask. */
 879                 if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
 880                         nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
 881                         nf_bridge->physindev = (struct net_device *)in;
 882                 }
 883 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 884                 /* the iptables outdev is br0.x, not br0 */
 885                 if (out->priv_flags & IFF_802_1Q_VLAN)
 886                         nf_bridge->netoutdev = (struct net_device *)out;
 887 #endif
 888                 return NF_STOP;
 889         }
 890
 891         return NF_ACCEPT;
 892 }
 893
 894 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 895  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 896  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 897  * ip_refrag() can return NF_STOLEN. */
 898 static struct nf_hook_ops br_nf_ops[] = {
 899         { .hook = br_nf_pre_routing,
 900           .owner = THIS_MODULE,
 901           .pf = PF_BRIDGE,
 902           .hooknum = NF_BR_PRE_ROUTING,
 903           .priority = NF_BR_PRI_BRNF, },
 904         { .hook = br_nf_local_in,
 905           .owner = THIS_MODULE,
 906           .pf = PF_BRIDGE,
 907           .hooknum = NF_BR_LOCAL_IN,
 908           .priority = NF_BR_PRI_BRNF, },
 909         { .hook = br_nf_forward_ip,
 910           .owner = THIS_MODULE,
 911           .pf = PF_BRIDGE,
 912           .hooknum = NF_BR_FORWARD,
 913           .priority = NF_BR_PRI_BRNF - 1, },
 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         { .hook = br_nf_local_out,
 920           .owner = THIS_MODULE,
 921           .pf = PF_BRIDGE,
 922           .hooknum = NF_BR_LOCAL_OUT,
 923           .priority = NF_BR_PRI_FIRST, },
 924         { .hook = br_nf_post_routing,
 925           .owner = THIS_MODULE,
 926           .pf = PF_BRIDGE,
 927           .hooknum = NF_BR_POST_ROUTING,
 928           .priority = NF_BR_PRI_LAST, },
 929         { .hook = ip_sabotage_in,
 930           .owner = THIS_MODULE,
 931           .pf = PF_INET,
 932           .hooknum = NF_IP_PRE_ROUTING,
 933           .priority = NF_IP_PRI_FIRST, },
 934         { .hook = ip_sabotage_in,
 935           .owner = THIS_MODULE,
 936           .pf = PF_INET6,
 937           .hooknum = NF_IP6_PRE_ROUTING,
 938           .priority = NF_IP6_PRI_FIRST, },
 939         { .hook = ip_sabotage_out,
 940           .owner = THIS_MODULE,
 941           .pf = PF_INET,
 942           .hooknum = NF_IP_FORWARD,
 943           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
 944         { .hook = ip_sabotage_out,
 945           .owner = THIS_MODULE,
 946           .pf = PF_INET6,
 947           .hooknum = NF_IP6_FORWARD,
 948           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
 949         { .hook = ip_sabotage_out,
 950           .owner = THIS_MODULE,
 951           .pf = PF_INET,
 952           .hooknum = NF_IP_LOCAL_OUT,
 953           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 954         { .hook = ip_sabotage_out,
 955           .owner = THIS_MODULE,
 956           .pf = PF_INET6,
 957           .hooknum = NF_IP6_LOCAL_OUT,
 958           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 959         { .hook = ip_sabotage_out,
 960           .owner = THIS_MODULE,
 961           .pf = PF_INET,
 962           .hooknum = NF_IP_POST_ROUTING,
 963           .priority = NF_IP_PRI_FIRST, },
 964         { .hook = ip_sabotage_out,
 965           .owner = THIS_MODULE,
 966           .pf = PF_INET6,
 967           .hooknum = NF_IP6_POST_ROUTING,
 968           .priority = NF_IP6_PRI_FIRST, },
 969 };
 970
 971 #ifdef CONFIG_SYSCTL
 972 static
 973 int brnf_sysctl_call_tables(ctl_table *ctl, int write, struct file * filp,
 974                         void __user *buffer, size_t *lenp, loff_t *ppos)
 975 {
 976         int ret;
 977
 978         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 979
 980         if (write && *(int *)(ctl->data))
 981                 *(int *)(ctl->data) = 1;
 982         return ret;
 983 }
 984
 985 static ctl_table brnf_table[] = {
 986         {
 987                 .ctl_name       = NET_BRIDGE_NF_CALL_ARPTABLES,
 988                 .procname       = "bridge-nf-call-arptables",
 989                 .data           = &brnf_call_arptables,
 990                 .maxlen         = sizeof(int),
 991                 .mode           = 0644,
 992                 .proc_handler   = &brnf_sysctl_call_tables,
 993         },
 994         {
 995                 .ctl_name       = NET_BRIDGE_NF_CALL_IPTABLES,
 996                 .procname       = "bridge-nf-call-iptables",
 997                 .data           = &brnf_call_iptables,
 998                 .maxlen         = sizeof(int),
 999                 .mode           = 0644,
1000                 .proc_handler   = &brnf_sysctl_call_tables,
1001         },
1002         {
1003                 .ctl_name       = NET_BRIDGE_NF_CALL_IP6TABLES,
1004                 .procname       = "bridge-nf-call-ip6tables",
1005                 .data           = &brnf_call_ip6tables,
1006                 .maxlen         = sizeof(int),
1007                 .mode           = 0644,
1008                 .proc_handler   = &brnf_sysctl_call_tables,
1009         },
1010         {
1011                 .ctl_name       = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
1012                 .procname       = "bridge-nf-filter-vlan-tagged",
1013                 .data           = &brnf_filter_vlan_tagged,
1014                 .maxlen         = sizeof(int),
1015                 .mode           = 0644,
1016                 .proc_handler   = &brnf_sysctl_call_tables,
1017         },
1018         { .ctl_name = 0 }
1019 };
1020
1021 static ctl_table brnf_bridge_table[] = {
1022         {
1023                 .ctl_name       = NET_BRIDGE,
1024                 .procname       = "bridge",
1025                 .mode           = 0555,
1026                 .child          = brnf_table,
1027         },
1028         { .ctl_name = 0 }
1029 };
1030
1031 static ctl_table brnf_net_table[] = {
1032         {
1033                 .ctl_name       = CTL_NET,
1034                 .procname       = "net",
1035                 .mode           = 0555,
1036                 .child          = brnf_bridge_table,
1037         },
1038         { .ctl_name = 0 }
1039 };
1040 #endif
1041
1042 int br_netfilter_init(void)
1043 {
1044         int i;
1045
1046         for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
1047                 int ret;
1048
1049                 if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
1050                         continue;
1051
1052                 while (i--)
1053                         nf_unregister_hook(&br_nf_ops[i]);
1054
1055                 return ret;
1056         }
1057
1058 #ifdef CONFIG_SYSCTL
1059         brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
1060         if (brnf_sysctl_header == NULL) {
1061                 printk(KERN_WARNING "br_netfilter: can't register to sysctl.\n");
1062                 for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
1063                         nf_unregister_hook(&br_nf_ops[i]);
1064                 return -EFAULT;
1065         }
1066 #endif
1067
1068         printk(KERN_NOTICE "Bridge firewalling registered\n");
1069
1070         return 0;
1071 }
1072
1073 void br_netfilter_fini(void)
1074 {
1075         int i;
1076
1077         for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
1078                 nf_unregister_hook(&br_nf_ops[i]);
1079 #ifdef CONFIG_SYSCTL
1080         unregister_sysctl_table(brnf_sysctl_header);
1081 #endif
1082 }