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