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_ether.h>
  30 #include <linux/if_vlan.h>
  31 #include <linux/netfilter_bridge.h>
  32 #include <linux/netfilter_ipv4.h>
  33 #include <linux/netfilter_ipv6.h>
  34 #include <linux/netfilter_arp.h>
  35 #include <linux/in_route.h>
  36 #include <net/ip.h>
  37 #include <net/ipv6.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/checksum.h>
  40 #include "br_private.h"
  41 #ifdef CONFIG_SYSCTL
  42 #include <linux/sysctl.h>
  43 #endif
  44
  45 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  46                                  (skb->nf_bridge->data))->daddr.ipv4)
  47 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = (skb)->nh.iph->daddr)
  48 #define dnat_took_place(skb)     (skb_origaddr(skb) != (skb)->nh.iph->daddr)
  49
  50 #define has_bridge_parent(device)       ((device)->br_port != NULL)
  51 #define bridge_parent(device)           ((device)->br_port->br->dev)
  52
  53 #ifdef CONFIG_SYSCTL
  54 static struct ctl_table_header *brnf_sysctl_header;
  55 static int brnf_call_iptables = 1;
  56 static int brnf_call_ip6tables = 1;
  57 static int brnf_call_arptables = 1;
  58 static int brnf_filter_vlan_tagged = 1;
  59 #else
  60 #define brnf_filter_vlan_tagged 1
  61 #endif
  62
  63 #define IS_VLAN_IP (skb->protocol == __constant_htons(ETH_P_8021Q) &&    \
  64         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IP) &&  \
  65         brnf_filter_vlan_tagged)
  66 #define IS_VLAN_IPV6 (skb->protocol == __constant_htons(ETH_P_8021Q) &&    \
  67         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_IPV6) &&  \
  68         brnf_filter_vlan_tagged)
  69 #define IS_VLAN_ARP (skb->protocol == __constant_htons(ETH_P_8021Q) &&   \
  70         hdr->h_vlan_encapsulated_proto == __constant_htons(ETH_P_ARP) && \
  71         brnf_filter_vlan_tagged)
  72
  73 /* We need these fake structures to make netfilter happy --
  74  * lots of places assume that skb->dst != NULL, which isn't
  75  * all that unreasonable.
  76  *
  77  * Currently, we fill in the PMTU entry because netfilter
  78  * refragmentation needs it, and the rt_flags entry because
  79  * ipt_REJECT needs it.  Future netfilter modules might
  80  * require us to fill additional fields. */
  81 static struct net_device __fake_net_device = {
  82         .hard_header_len        = ETH_HLEN
  83 };
  84
  85 static struct rtable __fake_rtable = {
  86         .u = {
  87                 .dst = {
  88                         .__refcnt               = ATOMIC_INIT(1),
  89                         .dev                    = &__fake_net_device,
  90                         .path                   = &__fake_rtable.u.dst,
  91                         .metrics                = {[RTAX_MTU - 1] = 1500},
  92                 }
  93         },
  94         .rt_flags       = 0,
  95 };
  96
  97
  98 /* PF_BRIDGE/PRE_ROUTING *********************************************/
  99 /* Undo the changes made for ip6tables PREROUTING and continue the
 100  * bridge PRE_ROUTING hook. */
 101 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 102 {
 103         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 104
 105 #ifdef CONFIG_NETFILTER_DEBUG
 106         skb->nf_debug ^= (1 << NF_BR_PRE_ROUTING);
 107 #endif
 108
 109         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 110                 skb->pkt_type = PACKET_OTHERHOST;
 111                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 112         }
 113         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 114
 115         skb->dst = (struct dst_entry *)&__fake_rtable;
 116         dst_hold(skb->dst);
 117
 118         skb->dev = nf_bridge->physindev;
 119         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 120                 skb_push(skb, VLAN_HLEN);
 121                 skb->nh.raw -= VLAN_HLEN;
 122         }
 123         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 124                        br_handle_frame_finish, 1);
 125
 126         return 0;
 127 }
 128
 129 static void __br_dnat_complain(void)
 130 {
 131         static unsigned long last_complaint;
 132
 133         if (jiffies - last_complaint >= 5 * HZ) {
 134                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 135                         "forwarding to be enabled\n");
 136                 last_complaint = jiffies;
 137         }
 138 }
 139
 140 /* This requires some explaining. If DNAT has taken place,
 141  * we will need to fix up the destination Ethernet address,
 142  * and this is a tricky process.
 143  *
 144  * There are two cases to consider:
 145  * 1. The packet was DNAT'ed to a device in the same bridge
 146  *    port group as it was received on. We can still bridge
 147  *    the packet.
 148  * 2. The packet was DNAT'ed to a different device, either
 149  *    a non-bridged device or another bridge port group.
 150  *    The packet will need to be routed.
 151  *
 152  * The correct way of distinguishing between these two cases is to
 153  * call ip_route_input() and to look at skb->dst->dev, which is
 154  * changed to the destination device if ip_route_input() succeeds.
 155  *
 156  * Let us first consider the case that ip_route_input() succeeds:
 157  *
 158  * If skb->dst->dev equals the logical bridge device the packet
 159  * came in on, we can consider this bridging. We then call
 160  * skb->dst->output() which will make the packet enter br_nf_local_out()
 161  * not much later. In that function it is assured that the iptables
 162  * FORWARD chain is traversed for the packet.
 163  *
 164  * Otherwise, the packet is considered to be routed and we just
 165  * change the destination MAC address so that the packet will
 166  * later be passed up to the IP stack to be routed.
 167  *
 168  * Let us now consider the case that ip_route_input() fails:
 169  *
 170  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 171  * will fail, while __ip_route_output_key() will return success. The source
 172  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 173  * thinks we're handling a locally generated packet and won't care
 174  * if IP forwarding is allowed. We send a warning message to the users's
 175  * log telling her to put IP forwarding on.
 176  *
 177  * ip_route_input() will also fail if there is no route available.
 178  * In that case we just drop the packet.
 179  *
 180  * --Lennert, 20020411
 181  * --Bart, 20020416 (updated)
 182  * --Bart, 20021007 (updated) */
 183 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 184 {
 185 #ifdef CONFIG_NETFILTER_DEBUG
 186         skb->nf_debug |= (1 << NF_BR_PRE_ROUTING) | (1 << NF_BR_FORWARD);
 187 #endif
 188
 189         if (skb->pkt_type == PACKET_OTHERHOST) {
 190                 skb->pkt_type = PACKET_HOST;
 191                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 192         }
 193         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 194
 195         skb->dev = bridge_parent(skb->dev);
 196         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 197                 skb_pull(skb, VLAN_HLEN);
 198                 skb->nh.raw += VLAN_HLEN;
 199         }
 200         skb->dst->output(skb);
 201         return 0;
 202 }
 203
 204 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 205 {
 206         struct net_device *dev = skb->dev;
 207         struct iphdr *iph = skb->nh.iph;
 208         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 209
 210 #ifdef CONFIG_NETFILTER_DEBUG
 211         skb->nf_debug ^= (1 << NF_BR_PRE_ROUTING);
 212 #endif
 213
 214         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 215                 skb->pkt_type = PACKET_OTHERHOST;
 216                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 217         }
 218         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 219
 220         if (dnat_took_place(skb)) {
 221                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos,
 222                     dev)) {
 223                         struct rtable *rt;
 224                         struct flowi fl = { .nl_u =
 225                         { .ip4_u = { .daddr = iph->daddr, .saddr = 0 ,
 226                                      .tos = RT_TOS(iph->tos)} }, .proto = 0};
 227
 228                         if (!ip_route_output_key(&rt, &fl)) {
 229                                 /* Bridged-and-DNAT'ed traffic doesn't
 230                                  * require ip_forwarding. */
 231                                 if (((struct dst_entry *)rt)->dev == dev) {
 232                                         skb->dst = (struct dst_entry *)rt;
 233                                         goto bridged_dnat;
 234                                 }
 235                                 __br_dnat_complain();
 236                                 dst_release((struct dst_entry *)rt);
 237                         }
 238                         kfree_skb(skb);
 239                         return 0;
 240                 } else {
 241                         if (skb->dst->dev == dev) {
 242 bridged_dnat:
 243                                 /* Tell br_nf_local_out this is a
 244                                  * bridged frame */
 245                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 246                                 skb->dev = nf_bridge->physindev;
 247                                 if (skb->protocol ==
 248                                     __constant_htons(ETH_P_8021Q)) {
 249                                         skb_push(skb, VLAN_HLEN);
 250                                         skb->nh.raw -= VLAN_HLEN;
 251                                 }
 252                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 253                                                skb, skb->dev, NULL,
 254                                                br_nf_pre_routing_finish_bridge,
 255                                                1);
 256                                 return 0;
 257                         }
 258                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr,
 259                                ETH_ALEN);
 260                         skb->pkt_type = PACKET_HOST;
 261                 }
 262         } else {
 263                 skb->dst = (struct dst_entry *)&__fake_rtable;
 264                 dst_hold(skb->dst);
 265         }
 266
 267         skb->dev = nf_bridge->physindev;
 268         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 269                 skb_push(skb, VLAN_HLEN);
 270                 skb->nh.raw -= VLAN_HLEN;
 271         }
 272         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 273                        br_handle_frame_finish, 1);
 274
 275         return 0;
 276 }
 277
 278 /* Some common code for IPv4/IPv6 */
 279 static void setup_pre_routing(struct sk_buff *skb)
 280 {
 281         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 282
 283         if (skb->pkt_type == PACKET_OTHERHOST) {
 284                 skb->pkt_type = PACKET_HOST;
 285                 nf_bridge->mask |= BRNF_PKT_TYPE;
 286         }
 287
 288         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 289         nf_bridge->physindev = skb->dev;
 290         skb->dev = bridge_parent(skb->dev);
 291 }
 292
 293 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 294 static int check_hbh_len(struct sk_buff *skb)
 295 {
 296         unsigned char *raw = (u8*)(skb->nh.ipv6h+1);
 297         u32 pkt_len;
 298         int off = raw - skb->nh.raw;
 299         int len = (raw[1]+1)<<3;
 300
 301         if ((raw + len) - skb->data > skb_headlen(skb))
 302                 goto bad;
 303
 304         off += 2;
 305         len -= 2;
 306
 307         while (len > 0) {
 308                 int optlen = raw[off+1]+2;
 309
 310                 switch (skb->nh.raw[off]) {
 311                 case IPV6_TLV_PAD0:
 312                         optlen = 1;
 313                         break;
 314
 315                 case IPV6_TLV_PADN:
 316                         break;
 317
 318                 case IPV6_TLV_JUMBO:
 319                         if (skb->nh.raw[off+1] != 4 || (off&3) != 2)
 320                                 goto bad;
 321
 322                         pkt_len = ntohl(*(u32*)(skb->nh.raw+off+2));
 323
 324                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 325                                 goto bad;
 326                         if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
 327                                 if (__pskb_trim(skb,
 328                                     pkt_len + sizeof(struct ipv6hdr)))
 329                                         goto bad;
 330                                 if (skb->ip_summed == CHECKSUM_HW)
 331                                         skb->ip_summed = CHECKSUM_NONE;
 332                         }
 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 #ifdef CONFIG_NETFILTER_DEBUG
 386         skb->nf_debug ^= (1 << NF_IP6_PRE_ROUTING);
 387 #endif
 388         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 389                 return NF_DROP;
 390         setup_pre_routing(skb);
 391
 392         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 393                 br_nf_pre_routing_finish_ipv6);
 394
 395         return NF_STOLEN;
 396
 397 inhdr_error:
 398         return NF_DROP;
 399 }
 400
 401 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 402  * Replicate the checks that IPv4 does on packet reception.
 403  * Set skb->dev to the bridge device (i.e. parent of the
 404  * receiving device) to make netfilter happy, the REDIRECT
 405  * target in particular.  Save the original destination IP
 406  * address to be able to detect DNAT afterwards. */
 407 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 408    const struct net_device *in, 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                         skb_pull(skb, VLAN_HLEN);
 427                         (skb)->nh.raw += VLAN_HLEN;
 428                 }
 429                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 430         }
 431 #ifdef CONFIG_SYSCTL
 432         if (!brnf_call_iptables)
 433                 return NF_ACCEPT;
 434 #endif
 435
 436         if (skb->protocol != __constant_htons(ETH_P_IP) && !IS_VLAN_IP)
 437                 return NF_ACCEPT;
 438
 439         if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 440                 goto out;
 441
 442         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 443                 skb_pull(skb, VLAN_HLEN);
 444                 (skb)->nh.raw += VLAN_HLEN;
 445         }
 446
 447         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 448                 goto inhdr_error;
 449
 450         iph = skb->nh.iph;
 451         if (iph->ihl < 5 || iph->version != 4)
 452                 goto inhdr_error;
 453
 454         if (!pskb_may_pull(skb, 4*iph->ihl))
 455                 goto inhdr_error;
 456
 457         iph = skb->nh.iph;
 458         if (ip_fast_csum((__u8 *)iph, iph->ihl) != 0)
 459                 goto inhdr_error;
 460
 461         len = ntohs(iph->tot_len);
 462         if (skb->len < len || len < 4*iph->ihl)
 463                 goto inhdr_error;
 464
 465         if (skb->len > len) {
 466                 __pskb_trim(skb, len);
 467                 if (skb->ip_summed == CHECKSUM_HW)
 468                         skb->ip_summed = CHECKSUM_NONE;
 469         }
 470
 471 #ifdef CONFIG_NETFILTER_DEBUG
 472         skb->nf_debug ^= (1 << NF_IP_PRE_ROUTING);
 473 #endif
 474         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 475                 return NF_DROP;
 476         setup_pre_routing(skb);
 477         store_orig_dstaddr(skb);
 478
 479         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 480                 br_nf_pre_routing_finish);
 481
 482         return NF_STOLEN;
 483
 484 inhdr_error:
 485 //      IP_INC_STATS_BH(IpInHdrErrors);
 486 out:
 487         return NF_DROP;
 488 }
 489
 490
 491 /* PF_BRIDGE/LOCAL_IN ************************************************/
 492 /* The packet is locally destined, which requires a real
 493  * dst_entry, so detach the fake one.  On the way up, the
 494  * packet would pass through PRE_ROUTING again (which already
 495  * took place when the packet entered the bridge), but we
 496  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 497  * prevent this from happening. */
 498 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
 499    const struct net_device *in, const struct net_device *out,
 500    int (*okfn)(struct sk_buff *))
 501 {
 502         struct sk_buff *skb = *pskb;
 503
 504         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 505                 dst_release(skb->dst);
 506                 skb->dst = NULL;
 507         }
 508
 509         return NF_ACCEPT;
 510 }
 511
 512
 513 /* PF_BRIDGE/FORWARD *************************************************/
 514 static int br_nf_forward_finish(struct sk_buff *skb)
 515 {
 516         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 517         struct net_device *in;
 518         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 519
 520 #ifdef CONFIG_NETFILTER_DEBUG
 521         skb->nf_debug ^= (1 << NF_BR_FORWARD);
 522 #endif
 523
 524         if (skb->protocol != __constant_htons(ETH_P_ARP) && !IS_VLAN_ARP) {
 525                 in = nf_bridge->physindev;
 526                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 527                         skb->pkt_type = PACKET_OTHERHOST;
 528                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 529                 }
 530         } else {
 531                 in = *((struct net_device **)(skb->cb));
 532         }
 533         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 534                 skb_push(skb, VLAN_HLEN);
 535                 skb->nh.raw -= VLAN_HLEN;
 536         }
 537         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 538                         skb->dev, br_forward_finish, 1);
 539         return 0;
 540 }
 541
 542 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 543  * netfilter with indev and outdev set to the bridge device,
 544  * but we are still able to filter on the 'real' indev/outdev
 545  * because of the physdev module. For ARP, indev and outdev are the
 546  * bridge ports. */
 547 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
 548    const struct net_device *in, const struct net_device *out,
 549    int (*okfn)(struct sk_buff *))
 550 {
 551         struct sk_buff *skb = *pskb;
 552         struct nf_bridge_info *nf_bridge;
 553         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 554         int pf;
 555
 556         if (!skb->nf_bridge)
 557                 return NF_ACCEPT;
 558
 559         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 560                 pf = PF_INET;
 561         else
 562                 pf = PF_INET6;
 563
 564         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 565                 skb_pull(*pskb, VLAN_HLEN);
 566                 (*pskb)->nh.raw += VLAN_HLEN;
 567         }
 568
 569 #ifdef CONFIG_NETFILTER_DEBUG
 570         skb->nf_debug ^= (1 << NF_BR_FORWARD);
 571 #endif
 572         nf_bridge = skb->nf_bridge;
 573         if (skb->pkt_type == PACKET_OTHERHOST) {
 574                 skb->pkt_type = PACKET_HOST;
 575                 nf_bridge->mask |= BRNF_PKT_TYPE;
 576         }
 577
 578         /* The physdev module checks on this */
 579         nf_bridge->mask |= BRNF_BRIDGED;
 580         nf_bridge->physoutdev = skb->dev;
 581
 582         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in),
 583                 bridge_parent(out), br_nf_forward_finish);
 584
 585         return NF_STOLEN;
 586 }
 587
 588 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
 589    const struct net_device *in, const struct net_device *out,
 590    int (*okfn)(struct sk_buff *))
 591 {
 592         struct sk_buff *skb = *pskb;
 593         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 594         struct net_device **d = (struct net_device **)(skb->cb);
 595
 596 #ifdef CONFIG_SYSCTL
 597         if (!brnf_call_arptables)
 598                 return NF_ACCEPT;
 599 #endif
 600
 601         if (skb->protocol != __constant_htons(ETH_P_ARP)) {
 602                 if (!IS_VLAN_ARP)
 603                         return NF_ACCEPT;
 604                 skb_pull(*pskb, VLAN_HLEN);
 605                 (*pskb)->nh.raw += VLAN_HLEN;
 606         }
 607
 608 #ifdef CONFIG_NETFILTER_DEBUG
 609         skb->nf_debug ^= (1 << NF_BR_FORWARD);
 610 #endif
 611
 612         if (skb->nh.arph->ar_pln != 4) {
 613                 if (IS_VLAN_ARP) {
 614                         skb_push(*pskb, VLAN_HLEN);
 615                         (*pskb)->nh.raw -= VLAN_HLEN;
 616                 }
 617                 return NF_ACCEPT;
 618         }
 619         *d = (struct net_device *)in;
 620         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 621                 (struct net_device *)out, br_nf_forward_finish);
 622
 623         return NF_STOLEN;
 624 }
 625
 626
 627 /* PF_BRIDGE/LOCAL_OUT ***********************************************/
 628 static int br_nf_local_out_finish(struct sk_buff *skb)
 629 {
 630 #ifdef CONFIG_NETFILTER_DEBUG
 631         skb->nf_debug &= ~(1 << NF_BR_LOCAL_OUT);
 632 #endif
 633         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 634                 skb_push(skb, VLAN_HLEN);
 635                 skb->nh.raw -= VLAN_HLEN;
 636         }
 637
 638         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 639                         br_forward_finish, NF_BR_PRI_FIRST + 1);
 640
 641         return 0;
 642 }
 643
 644 /* This function sees both locally originated IP packets and forwarded
 645  * IP packets (in both cases the destination device is a bridge
 646  * device). It also sees bridged-and-DNAT'ed packets.
 647  * To be able to filter on the physical bridge devices (with the physdev
 648  * module), we steal packets destined to a bridge device away from the
 649  * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
 650  * when we have determined the real output device. This is done in here.
 651  *
 652  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 653  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 654  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 655  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 656  * will be executed.
 657  * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
 658  * this packet before, and so the packet was locally originated. We fake
 659  * the PF_INET/LOCAL_OUT hook.
 660  * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
 661  * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
 662  * even routed packets that didn't arrive on a bridge interface have their
 663  * nf_bridge->physindev set. */
 664 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
 665    const struct net_device *in, const struct net_device *out,
 666    int (*okfn)(struct sk_buff *))
 667 {
 668         struct net_device *realindev, *realoutdev;
 669         struct sk_buff *skb = *pskb;
 670         struct nf_bridge_info *nf_bridge;
 671         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 672         int pf;
 673
 674         if (!skb->nf_bridge)
 675                 return NF_ACCEPT;
 676
 677         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 678                 pf = PF_INET;
 679         else
 680                 pf = PF_INET6;
 681
 682 #ifdef CONFIG_NETFILTER_DEBUG
 683         /* Sometimes we get packets with NULL ->dst here (for example,
 684          * running a dhcp client daemon triggers this). This should now
 685          * be fixed, but let's keep the check around. */
 686         if (skb->dst == NULL) {
 687                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 688                 return NF_ACCEPT;
 689         }
 690 #endif
 691
 692         nf_bridge = skb->nf_bridge;
 693         nf_bridge->physoutdev = skb->dev;
 694         realindev = nf_bridge->physindev;
 695
 696         /* Bridged, take PF_BRIDGE/FORWARD.
 697          * (see big note in front of br_nf_pre_routing_finish) */
 698         if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
 699                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 700                         skb->pkt_type = PACKET_OTHERHOST;
 701                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 702                 }
 703                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 704                         skb_push(skb, VLAN_HLEN);
 705                         skb->nh.raw -= VLAN_HLEN;
 706                 }
 707
 708                 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
 709                         skb->dev, br_forward_finish);
 710                 goto out;
 711         }
 712         realoutdev = bridge_parent(skb->dev);
 713
 714 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 715         /* iptables should match -o br0.x */
 716         if (nf_bridge->netoutdev)
 717                 realoutdev = nf_bridge->netoutdev;
 718 #endif
 719         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 720                 skb_pull(skb, VLAN_HLEN);
 721                 (*pskb)->nh.raw += VLAN_HLEN;
 722         }
 723         /* IP forwarded traffic has a physindev, locally
 724          * generated traffic hasn't. */
 725         if (realindev != NULL) {
 726                 if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) &&
 727                     has_bridge_parent(realindev))
 728                         realindev = bridge_parent(realindev);
 729
 730                 NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
 731                                realoutdev, br_nf_local_out_finish,
 732                                NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
 733         } else {
 734 #ifdef CONFIG_NETFILTER_DEBUG
 735                 skb->nf_debug ^= (1 << NF_IP_LOCAL_OUT);
 736 #endif
 737
 738                 NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
 739                                realoutdev, br_nf_local_out_finish,
 740                                NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
 741         }
 742
 743 out:
 744         return NF_STOLEN;
 745 }
 746
 747
 748 /* PF_BRIDGE/POST_ROUTING ********************************************/
 749 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
 750    const struct net_device *in, const struct net_device *out,
 751    int (*okfn)(struct sk_buff *))
 752 {
 753         struct sk_buff *skb = *pskb;
 754         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
 755         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 756         struct net_device *realoutdev = bridge_parent(skb->dev);
 757         int pf;
 758
 759 #ifdef CONFIG_NETFILTER_DEBUG
 760         /* Be very paranoid. This probably won't happen anymore, but let's
 761          * keep the check just to be sure... */
 762         if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
 763                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 764                                  "bad mac.raw pointer.");
 765                 goto print_error;
 766         }
 767 #endif
 768
 769         if (!nf_bridge)
 770                 return NF_ACCEPT;
 771
 772         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 773                 pf = PF_INET;
 774         else
 775                 pf = PF_INET6;
 776
 777 #ifdef CONFIG_NETFILTER_DEBUG
 778         if (skb->dst == NULL) {
 779                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 780                 goto print_error;
 781         }
 782
 783         skb->nf_debug ^= (1 << NF_IP_POST_ROUTING);
 784 #endif
 785
 786         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 787          * about the value of skb->pkt_type. */
 788         if (skb->pkt_type == PACKET_OTHERHOST) {
 789                 skb->pkt_type = PACKET_HOST;
 790                 nf_bridge->mask |= BRNF_PKT_TYPE;
 791         }
 792
 793         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 794                 skb_pull(skb, VLAN_HLEN);
 795                 skb->nh.raw += VLAN_HLEN;
 796         }
 797
 798         nf_bridge_save_header(skb);
 799
 800 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 801         if (nf_bridge->netoutdev)
 802                 realoutdev = nf_bridge->netoutdev;
 803 #endif
 804         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
 805                 br_dev_queue_push_xmit);
 806
 807         return NF_STOLEN;
 808
 809 #ifdef CONFIG_NETFILTER_DEBUG
 810 print_error:
 811         if (skb->dev != NULL) {
 812                 printk("[%s]", skb->dev->name);
 813                 if (has_bridge_parent(skb->dev))
 814                         printk("[%s]", bridge_parent(skb->dev)->name);
 815         }
 816         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
 817                                               skb->data);
 818         return NF_ACCEPT;
 819 #endif
 820 }
 821
 822
 823 /* IP/SABOTAGE *****************************************************/
 824 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 825  * for the second time. */
 826 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
 827    const struct net_device *in, const struct net_device *out,
 828    int (*okfn)(struct sk_buff *))
 829 {
 830         if ((*pskb)->nf_bridge &&
 831             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 832                 return NF_STOP;
 833         }
 834
 835         return NF_ACCEPT;
 836 }
 837
 838 /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
 839  * and PF_INET(6)/POST_ROUTING until we have done the forwarding
 840  * decision in the bridge code and have determined nf_bridge->physoutdev. */
 841 static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 842    const struct net_device *in, const struct net_device *out,
 843    int (*okfn)(struct sk_buff *))
 844 {
 845         struct sk_buff *skb = *pskb;
 846
 847         if ((out->hard_start_xmit == br_dev_xmit &&
 848             okfn != br_nf_forward_finish &&
 849             okfn != br_nf_local_out_finish &&
 850             okfn != br_dev_queue_push_xmit)
 851 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 852             || ((out->priv_flags & IFF_802_1Q_VLAN) &&
 853             VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
 854 #endif
 855             ) {
 856                 struct nf_bridge_info *nf_bridge;
 857
 858                 if (!skb->nf_bridge) {
 859 #ifdef CONFIG_SYSCTL
 860                         /* This code is executed while in the IP(v6) stack,
 861                            the version should be 4 or 6. We can't use
 862                            skb->protocol because that isn't set on
 863                            PF_INET(6)/LOCAL_OUT. */
 864                         struct iphdr *ip = skb->nh.iph;
 865
 866                         if (ip->version == 4 && !brnf_call_iptables)
 867                                 return NF_ACCEPT;
 868                         else if (ip->version == 6 && !brnf_call_ip6tables)
 869                                 return NF_ACCEPT;
 870 #endif
 871                         if (hook == NF_IP_POST_ROUTING)
 872                                 return NF_ACCEPT;
 873                         if (!nf_bridge_alloc(skb))
 874                                 return NF_DROP;
 875                 }
 876
 877                 nf_bridge = skb->nf_bridge;
 878
 879                 /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
 880                  * will need the indev then. For a brouter, the real indev
 881                  * can be a bridge port, so we make sure br_nf_local_out()
 882                  * doesn't use the bridge parent of the indev by using
 883                  * the BRNF_DONT_TAKE_PARENT mask. */
 884                 if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
 885                         nf_bridge->mask &= BRNF_DONT_TAKE_PARENT;
 886                         nf_bridge->physindev = (struct net_device *)in;
 887                 }
 888 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 889                 /* the iptables outdev is br0.x, not br0 */
 890                 if (out->priv_flags & IFF_802_1Q_VLAN)
 891                         nf_bridge->netoutdev = (struct net_device *)out;
 892 #endif
 893                 return NF_STOP;
 894         }
 895
 896         return NF_ACCEPT;
 897 }
 898
 899 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 900  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 901  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 902  * ip_refrag() can return NF_STOLEN. */
 903 static struct nf_hook_ops br_nf_ops[] = {
 904         { .hook = br_nf_pre_routing,
 905           .owner = THIS_MODULE,
 906           .pf = PF_BRIDGE,
 907           .hooknum = NF_BR_PRE_ROUTING,
 908           .priority = NF_BR_PRI_BRNF, },
 909         { .hook = br_nf_local_in,
 910           .owner = THIS_MODULE,
 911           .pf = PF_BRIDGE,
 912           .hooknum = NF_BR_LOCAL_IN,
 913           .priority = NF_BR_PRI_BRNF, },
 914         { .hook = br_nf_forward_ip,
 915           .owner = THIS_MODULE,
 916           .pf = PF_BRIDGE,
 917           .hooknum = NF_BR_FORWARD,
 918           .priority = NF_BR_PRI_BRNF - 1, },
 919         { .hook = br_nf_forward_arp,
 920           .owner = THIS_MODULE,
 921           .pf = PF_BRIDGE,
 922           .hooknum = NF_BR_FORWARD,
 923           .priority = NF_BR_PRI_BRNF, },
 924         { .hook = br_nf_local_out,
 925           .owner = THIS_MODULE,
 926           .pf = PF_BRIDGE,
 927           .hooknum = NF_BR_LOCAL_OUT,
 928           .priority = NF_BR_PRI_FIRST, },
 929         { .hook = br_nf_post_routing,
 930           .owner = THIS_MODULE,
 931           .pf = PF_BRIDGE,
 932           .hooknum = NF_BR_POST_ROUTING,
 933           .priority = NF_BR_PRI_LAST, },
 934         { .hook = ip_sabotage_in,
 935           .owner = THIS_MODULE,
 936           .pf = PF_INET,
 937           .hooknum = NF_IP_PRE_ROUTING,
 938           .priority = NF_IP_PRI_FIRST, },
 939         { .hook = ip_sabotage_in,
 940           .owner = THIS_MODULE,
 941           .pf = PF_INET6,
 942           .hooknum = NF_IP6_PRE_ROUTING,
 943           .priority = NF_IP6_PRI_FIRST, },
 944         { .hook = ip_sabotage_out,
 945           .owner = THIS_MODULE,
 946           .pf = PF_INET,
 947           .hooknum = NF_IP_FORWARD,
 948           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
 949         { .hook = ip_sabotage_out,
 950           .owner = THIS_MODULE,
 951           .pf = PF_INET6,
 952           .hooknum = NF_IP6_FORWARD,
 953           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
 954         { .hook = ip_sabotage_out,
 955           .owner = THIS_MODULE,
 956           .pf = PF_INET,
 957           .hooknum = NF_IP_LOCAL_OUT,
 958           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 959         { .hook = ip_sabotage_out,
 960           .owner = THIS_MODULE,
 961           .pf = PF_INET6,
 962           .hooknum = NF_IP6_LOCAL_OUT,
 963           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 964         { .hook = ip_sabotage_out,
 965           .owner = THIS_MODULE,
 966           .pf = PF_INET,
 967           .hooknum = NF_IP_POST_ROUTING,
 968           .priority = NF_IP_PRI_FIRST, },
 969         { .hook = ip_sabotage_out,
 970           .owner = THIS_MODULE,
 971           .pf = PF_INET6,
 972           .hooknum = NF_IP6_POST_ROUTING,
 973           .priority = NF_IP6_PRI_FIRST, },
 974 };
 975
 976 #ifdef CONFIG_SYSCTL
 977 static
 978 int brnf_sysctl_call_tables(ctl_table *ctl, int write, struct file * filp,
 979                         void __user *buffer, size_t *lenp, loff_t *ppos)
 980 {
 981         int ret;
 982
 983         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 984
 985         if (write && *(int *)(ctl->data))
 986                 *(int *)(ctl->data) = 1;
 987         return ret;
 988 }
 989
 990 static ctl_table brnf_table[] = {
 991         {
 992                 .ctl_name       = NET_BRIDGE_NF_CALL_ARPTABLES,
 993                 .procname       = "bridge-nf-call-arptables",
 994                 .data           = &brnf_call_arptables,
 995                 .maxlen         = sizeof(int),
 996                 .mode           = 0644,
 997                 .proc_handler   = &brnf_sysctl_call_tables,
 998         },
 999         {
1000                 .ctl_name       = NET_BRIDGE_NF_CALL_IPTABLES,
1001                 .procname       = "bridge-nf-call-iptables",
1002                 .data           = &brnf_call_iptables,
1003                 .maxlen         = sizeof(int),
1004                 .mode           = 0644,
1005                 .proc_handler   = &brnf_sysctl_call_tables,
1006         },
1007         {
1008                 .ctl_name       = NET_BRIDGE_NF_CALL_IP6TABLES,
1009                 .procname       = "bridge-nf-call-ip6tables",
1010                 .data           = &brnf_call_ip6tables,
1011                 .maxlen         = sizeof(int),
1012                 .mode           = 0644,
1013                 .proc_handler   = &brnf_sysctl_call_tables,
1014         },
1015         {
1016                 .ctl_name       = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
1017                 .procname       = "bridge-nf-filter-vlan-tagged",
1018                 .data           = &brnf_filter_vlan_tagged,
1019                 .maxlen         = sizeof(int),
1020                 .mode           = 0644,
1021                 .proc_handler   = &brnf_sysctl_call_tables,
1022         },
1023         { .ctl_name = 0 }
1024 };
1025
1026 static ctl_table brnf_bridge_table[] = {
1027         {
1028                 .ctl_name       = NET_BRIDGE,
1029                 .procname       = "bridge",
1030                 .mode           = 0555,
1031                 .child          = brnf_table,
1032         },
1033         { .ctl_name = 0 }
1034 };
1035
1036 static ctl_table brnf_net_table[] = {
1037         {
1038                 .ctl_name       = CTL_NET,
1039                 .procname       = "net",
1040                 .mode           = 0555,
1041                 .child          = brnf_bridge_table,
1042         },
1043         { .ctl_name = 0 }
1044 };
1045 #endif
1046
1047 int br_netfilter_init(void)
1048 {
1049         int i;
1050
1051         for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
1052                 int ret;
1053
1054                 if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
1055                         continue;
1056
1057                 while (i--)
1058                         nf_unregister_hook(&br_nf_ops[i]);
1059
1060                 return ret;
1061         }
1062
1063 #ifdef CONFIG_SYSCTL
1064         brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
1065         if (brnf_sysctl_header == NULL) {
1066                 printk(KERN_WARNING "br_netfilter: can't register to sysctl.\n");
1067                 for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
1068                         nf_unregister_hook(&br_nf_ops[i]);
1069                 return -EFAULT;
1070         }
1071 #endif
1072
1073         printk(KERN_NOTICE "Bridge firewalling registered\n");
1074
1075         return 0;
1076 }
1077
1078 void br_netfilter_fini(void)
1079 {
1080         int i;
1081
1082         for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
1083                 nf_unregister_hook(&br_nf_ops[i]);
1084 #ifdef CONFIG_SYSCTL
1085         unregister_sysctl_table(brnf_sysctl_header);
1086 #endif
1087 }