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