net/bridge/br_netfilter.c

   1 /*
   2  *      Handle firewalling
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <buytenh@gnu.org>
   7  *      Bart De Schuymer (maintainer)   <bdschuym@pandora.be>
   8  *
   9  *      Changes:
  10  *      Apr 29 2003: physdev module support (bdschuym)
  11  *      Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
  12  *      Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
  13  *                   (bdschuym)
  14  *      Sep 01 2004: add IPv6 filtering (bdschuym)
  15  *
  16  *      This program is free software; you can redistribute it and/or
  17  *      modify it under the terms of the GNU General Public License
  18  *      as published by the Free Software Foundation; either version
  19  *      2 of the License, or (at your option) any later version.
  20  *
  21  *      Lennert dedicates this file to Kerstin Wurdinger.
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/ip.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/if_arp.h>
  30 #include <linux/if_ether.h>
  31 #include <linux/if_vlan.h>
  32 #include <linux/netfilter_bridge.h>
  33 #include <linux/netfilter_ipv4.h>
  34 #include <linux/netfilter_ipv6.h>
  35 #include <linux/netfilter_arp.h>
  36 #include <linux/in_route.h>
  37
  38 #include <net/ip.h>
  39 #include <net/ipv6.h>
  40 #include <net/route.h>
  41
  42 #include <asm/uaccess.h>
  43 #include <asm/checksum.h>
  44 #include "br_private.h"
  45 #ifdef CONFIG_SYSCTL
  46 #include <linux/sysctl.h>
  47 #endif
  48
  49 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  50                                  (skb->nf_bridge->data))->daddr.ipv4)
  51 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = (skb)->nh.iph->daddr)
  52 #define dnat_took_place(skb)     (skb_origaddr(skb) != (skb)->nh.iph->daddr)
  53
  54 #ifdef CONFIG_SYSCTL
  55 static struct ctl_table_header *brnf_sysctl_header;
  56 static int brnf_call_iptables = 1;
  57 static int brnf_call_ip6tables = 1;
  58 static int brnf_call_arptables = 1;
  59 static int brnf_filter_vlan_tagged = 1;
  60 #else
  61 #define brnf_filter_vlan_tagged 1
  62 #endif
  63
  64 int brnf_deferred_hooks;
  65 EXPORT_SYMBOL_GPL(brnf_deferred_hooks);
  66
  67 static __be16 inline vlan_proto(const struct sk_buff *skb)
  68 {
  69         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  70 }
  71
  72 #define IS_VLAN_IP(skb) \
  73         (skb->protocol == htons(ETH_P_8021Q) && \
  74          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  75          brnf_filter_vlan_tagged)
  76
  77 #define IS_VLAN_IPV6(skb) \
  78         (skb->protocol == htons(ETH_P_8021Q) && \
  79          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  80          brnf_filter_vlan_tagged)
  81
  82 #define IS_VLAN_ARP(skb) \
  83         (skb->protocol == htons(ETH_P_8021Q) && \
  84          vlan_proto(skb) == htons(ETH_P_ARP) && \
  85          brnf_filter_vlan_tagged)
  86
  87 /* We need these fake structures to make netfilter happy --
  88  * lots of places assume that skb->dst != NULL, which isn't
  89  * all that unreasonable.
  90  *
  91  * Currently, we fill in the PMTU entry because netfilter
  92  * refragmentation needs it, and the rt_flags entry because
  93  * ipt_REJECT needs it.  Future netfilter modules might
  94  * require us to fill additional fields. */
  95 static struct net_device __fake_net_device = {
  96         .hard_header_len        = ETH_HLEN
  97 };
  98
  99 static struct rtable __fake_rtable = {
 100         .u = {
 101                 .dst = {
 102                         .__refcnt               = ATOMIC_INIT(1),
 103                         .dev                    = &__fake_net_device,
 104                         .path                   = &__fake_rtable.u.dst,
 105                         .metrics                = {[RTAX_MTU - 1] = 1500},
 106                         .flags                  = DST_NOXFRM,
 107                 }
 108         },
 109         .rt_flags       = 0,
 110 };
 111
 112 static inline struct net_device *bridge_parent(const struct net_device *dev)
 113 {
 114         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 115
 116         return port ? port->br->dev : NULL;
 117 }
 118
 119 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 120 {
 121         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 122         if (likely(skb->nf_bridge))
 123                 atomic_set(&(skb->nf_bridge->use), 1);
 124
 125         return skb->nf_bridge;
 126 }
 127
 128 static inline void nf_bridge_save_header(struct sk_buff *skb)
 129 {
 130         int header_size = ETH_HLEN;
 131
 132         if (skb->protocol == htons(ETH_P_8021Q))
 133                 header_size += VLAN_HLEN;
 134
 135         memcpy(skb->nf_bridge->data, skb->data - header_size, header_size);
 136 }
 137
 138 /*
 139  * When forwarding bridge frames, we save a copy of the original
 140  * header before processing.
 141  */
 142 int nf_bridge_copy_header(struct sk_buff *skb)
 143 {
 144         int err;
 145         int header_size = ETH_HLEN;
 146
 147         if (skb->protocol == htons(ETH_P_8021Q))
 148                 header_size += VLAN_HLEN;
 149
 150         err = skb_cow(skb, header_size);
 151         if (err)
 152                 return err;
 153
 154         memcpy(skb->data - header_size, skb->nf_bridge->data, header_size);
 155
 156         if (skb->protocol == htons(ETH_P_8021Q))
 157                 __skb_push(skb, VLAN_HLEN);
 158         return 0;
 159 }
 160
 161 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 162 /* Undo the changes made for ip6tables PREROUTING and continue the
 163  * bridge PRE_ROUTING hook. */
 164 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 165 {
 166         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 167
 168         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 169                 skb->pkt_type = PACKET_OTHERHOST;
 170                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 171         }
 172         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 173
 174         skb->dst = (struct dst_entry *)&__fake_rtable;
 175         dst_hold(skb->dst);
 176
 177         skb->dev = nf_bridge->physindev;
 178         if (skb->protocol == htons(ETH_P_8021Q)) {
 179                 skb_push(skb, VLAN_HLEN);
 180                 skb->nh.raw -= VLAN_HLEN;
 181         }
 182         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 183                        br_handle_frame_finish, 1);
 184
 185         return 0;
 186 }
 187
 188 static void __br_dnat_complain(void)
 189 {
 190         static unsigned long last_complaint;
 191
 192         if (jiffies - last_complaint >= 5 * HZ) {
 193                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 194                        "forwarding to be enabled\n");
 195                 last_complaint = jiffies;
 196         }
 197 }
 198
 199 /* This requires some explaining. If DNAT has taken place,
 200  * we will need to fix up the destination Ethernet address,
 201  * and this is a tricky process.
 202  *
 203  * There are two cases to consider:
 204  * 1. The packet was DNAT'ed to a device in the same bridge
 205  *    port group as it was received on. We can still bridge
 206  *    the packet.
 207  * 2. The packet was DNAT'ed to a different device, either
 208  *    a non-bridged device or another bridge port group.
 209  *    The packet will need to be routed.
 210  *
 211  * The correct way of distinguishing between these two cases is to
 212  * call ip_route_input() and to look at skb->dst->dev, which is
 213  * changed to the destination device if ip_route_input() succeeds.
 214  *
 215  * Let us first consider the case that ip_route_input() succeeds:
 216  *
 217  * If skb->dst->dev equals the logical bridge device the packet
 218  * came in on, we can consider this bridging. We then call
 219  * skb->dst->output() which will make the packet enter br_nf_local_out()
 220  * not much later. In that function it is assured that the iptables
 221  * FORWARD chain is traversed for the packet.
 222  *
 223  * Otherwise, the packet is considered to be routed and we just
 224  * change the destination MAC address so that the packet will
 225  * later be passed up to the IP stack to be routed.
 226  *
 227  * Let us now consider the case that ip_route_input() fails:
 228  *
 229  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 230  * will fail, while __ip_route_output_key() will return success. The source
 231  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 232  * thinks we're handling a locally generated packet and won't care
 233  * if IP forwarding is allowed. We send a warning message to the users's
 234  * log telling her to put IP forwarding on.
 235  *
 236  * ip_route_input() will also fail if there is no route available.
 237  * In that case we just drop the packet.
 238  *
 239  * --Lennert, 20020411
 240  * --Bart, 20020416 (updated)
 241  * --Bart, 20021007 (updated) */
 242 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 243 {
 244         if (skb->pkt_type == PACKET_OTHERHOST) {
 245                 skb->pkt_type = PACKET_HOST;
 246                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 247         }
 248         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 249
 250         skb->dev = bridge_parent(skb->dev);
 251         if (!skb->dev)
 252                 kfree_skb(skb);
 253         else {
 254                 if (skb->protocol == htons(ETH_P_8021Q)) {
 255                         skb_pull(skb, VLAN_HLEN);
 256                         skb->nh.raw += VLAN_HLEN;
 257                 }
 258                 skb->dst->output(skb);
 259         }
 260         return 0;
 261 }
 262
 263 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 264 {
 265         struct net_device *dev = skb->dev;
 266         struct iphdr *iph = skb->nh.iph;
 267         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 268
 269         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 270                 skb->pkt_type = PACKET_OTHERHOST;
 271                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 272         }
 273         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 274
 275         if (dnat_took_place(skb)) {
 276                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev)) {
 277                         struct rtable *rt;
 278                         struct flowi fl = {
 279                                 .nl_u = {
 280                                         .ip4_u = {
 281                                                  .daddr = iph->daddr,
 282                                                  .saddr = 0,
 283                                                  .tos = RT_TOS(iph->tos) },
 284                                 },
 285                                 .proto = 0,
 286                         };
 287
 288                         if (!ip_route_output_key(&rt, &fl)) {
 289                                 /* - Bridged-and-DNAT'ed traffic doesn't
 290                                  *   require ip_forwarding.
 291                                  * - Deal with redirected traffic. */
 292                                 if (((struct dst_entry *)rt)->dev == dev ||
 293                                     rt->rt_type == RTN_LOCAL) {
 294                                         skb->dst = (struct dst_entry *)rt;
 295                                         goto bridged_dnat;
 296                                 }
 297                                 __br_dnat_complain();
 298                                 dst_release((struct dst_entry *)rt);
 299                         }
 300                         kfree_skb(skb);
 301                         return 0;
 302                 } else {
 303                         if (skb->dst->dev == dev) {
 304 bridged_dnat:
 305                                 /* Tell br_nf_local_out this is a
 306                                  * bridged frame */
 307                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 308                                 skb->dev = nf_bridge->physindev;
 309                                 if (skb->protocol ==
 310                                     htons(ETH_P_8021Q)) {
 311                                         skb_push(skb, VLAN_HLEN);
 312                                         skb->nh.raw -= VLAN_HLEN;
 313                                 }
 314                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 315                                                skb, skb->dev, NULL,
 316                                                br_nf_pre_routing_finish_bridge,
 317                                                1);
 318                                 return 0;
 319                         }
 320                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 321                         skb->pkt_type = PACKET_HOST;
 322                 }
 323         } else {
 324                 skb->dst = (struct dst_entry *)&__fake_rtable;
 325                 dst_hold(skb->dst);
 326         }
 327
 328         skb->dev = nf_bridge->physindev;
 329         if (skb->protocol == htons(ETH_P_8021Q)) {
 330                 skb_push(skb, VLAN_HLEN);
 331                 skb->nh.raw -= VLAN_HLEN;
 332         }
 333         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 334                        br_handle_frame_finish, 1);
 335
 336         return 0;
 337 }
 338
 339 /* Some common code for IPv4/IPv6 */
 340 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 341 {
 342         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 343
 344         if (skb->pkt_type == PACKET_OTHERHOST) {
 345                 skb->pkt_type = PACKET_HOST;
 346                 nf_bridge->mask |= BRNF_PKT_TYPE;
 347         }
 348
 349         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 350         nf_bridge->physindev = skb->dev;
 351         skb->dev = bridge_parent(skb->dev);
 352
 353         return skb->dev;
 354 }
 355
 356 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 357 static int check_hbh_len(struct sk_buff *skb)
 358 {
 359         unsigned char *raw = (u8 *) (skb->nh.ipv6h + 1);
 360         u32 pkt_len;
 361         int off = raw - skb->nh.raw;
 362         int len = (raw[1] + 1) << 3;
 363
 364         if ((raw + len) - skb->data > skb_headlen(skb))
 365                 goto bad;
 366
 367         off += 2;
 368         len -= 2;
 369
 370         while (len > 0) {
 371                 int optlen = skb->nh.raw[off + 1] + 2;
 372
 373                 switch (skb->nh.raw[off]) {
 374                 case IPV6_TLV_PAD0:
 375                         optlen = 1;
 376                         break;
 377
 378                 case IPV6_TLV_PADN:
 379                         break;
 380
 381                 case IPV6_TLV_JUMBO:
 382                         if (skb->nh.raw[off + 1] != 4 || (off & 3) != 2)
 383                                 goto bad;
 384                         pkt_len = ntohl(*(u32 *) (skb->nh.raw + off + 2));
 385                         if (pkt_len <= IPV6_MAXPLEN ||
 386                             skb->nh.ipv6h->payload_len)
 387                                 goto bad;
 388                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 389                                 goto bad;
 390                         if (pskb_trim_rcsum(skb,
 391                                             pkt_len + sizeof(struct ipv6hdr)))
 392                                 goto bad;
 393                         break;
 394                 default:
 395                         if (optlen > len)
 396                                 goto bad;
 397                         break;
 398                 }
 399                 off += optlen;
 400                 len -= optlen;
 401         }
 402         if (len == 0)
 403                 return 0;
 404 bad:
 405         return -1;
 406
 407 }
 408
 409 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 410  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 411 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 412                                            struct sk_buff *skb,
 413                                            const struct net_device *in,
 414                                            const struct net_device *out,
 415                                            int (*okfn)(struct sk_buff *))
 416 {
 417         struct ipv6hdr *hdr;
 418         u32 pkt_len;
 419
 420         if (skb->len < sizeof(struct ipv6hdr))
 421                 goto inhdr_error;
 422
 423         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 424                 goto inhdr_error;
 425
 426         hdr = skb->nh.ipv6h;
 427
 428         if (hdr->version != 6)
 429                 goto inhdr_error;
 430
 431         pkt_len = ntohs(hdr->payload_len);
 432
 433         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 434                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 435                         goto inhdr_error;
 436                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 437                         goto inhdr_error;
 438         }
 439         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 440                 goto inhdr_error;
 441
 442         nf_bridge_put(skb->nf_bridge);
 443         if (!nf_bridge_alloc(skb))
 444                 return NF_DROP;
 445         if (!setup_pre_routing(skb))
 446                 return NF_DROP;
 447
 448         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 449                 br_nf_pre_routing_finish_ipv6);
 450
 451         return NF_STOLEN;
 452
 453 inhdr_error:
 454         return NF_DROP;
 455 }
 456
 457 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 458  * Replicate the checks that IPv4 does on packet reception.
 459  * Set skb->dev to the bridge device (i.e. parent of the
 460  * receiving device) to make netfilter happy, the REDIRECT
 461  * target in particular.  Save the original destination IP
 462  * address to be able to detect DNAT afterwards. */
 463 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 464                                       const struct net_device *in,
 465                                       const struct net_device *out,
 466                                       int (*okfn)(struct sk_buff *))
 467 {
 468         struct iphdr *iph;
 469         __u32 len;
 470         struct sk_buff *skb = *pskb;
 471
 472         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb)) {
 473 #ifdef CONFIG_SYSCTL
 474                 if (!brnf_call_ip6tables)
 475                         return NF_ACCEPT;
 476 #endif
 477                 if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 478                         goto out;
 479
 480                 if (skb->protocol == htons(ETH_P_8021Q)) {
 481                         skb_pull_rcsum(skb, VLAN_HLEN);
 482                         skb->nh.raw += VLAN_HLEN;
 483                 }
 484                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 485         }
 486 #ifdef CONFIG_SYSCTL
 487         if (!brnf_call_iptables)
 488                 return NF_ACCEPT;
 489 #endif
 490
 491         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb))
 492                 return NF_ACCEPT;
 493
 494         if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 495                 goto out;
 496
 497         if (skb->protocol == htons(ETH_P_8021Q)) {
 498                 skb_pull_rcsum(skb, VLAN_HLEN);
 499                 skb->nh.raw += VLAN_HLEN;
 500         }
 501
 502         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 503                 goto inhdr_error;
 504
 505         iph = skb->nh.iph;
 506         if (iph->ihl < 5 || iph->version != 4)
 507                 goto inhdr_error;
 508
 509         if (!pskb_may_pull(skb, 4 * iph->ihl))
 510                 goto inhdr_error;
 511
 512         iph = skb->nh.iph;
 513         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 514                 goto inhdr_error;
 515
 516         len = ntohs(iph->tot_len);
 517         if (skb->len < len || len < 4 * iph->ihl)
 518                 goto inhdr_error;
 519
 520         pskb_trim_rcsum(skb, len);
 521
 522         nf_bridge_put(skb->nf_bridge);
 523         if (!nf_bridge_alloc(skb))
 524                 return NF_DROP;
 525         if (!setup_pre_routing(skb))
 526                 return NF_DROP;
 527         store_orig_dstaddr(skb);
 528
 529         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 530                 br_nf_pre_routing_finish);
 531
 532         return NF_STOLEN;
 533
 534 inhdr_error:
 535 //      IP_INC_STATS_BH(IpInHdrErrors);
 536 out:
 537         return NF_DROP;
 538 }
 539
 540
 541 /* PF_BRIDGE/LOCAL_IN ************************************************/
 542 /* The packet is locally destined, which requires a real
 543  * dst_entry, so detach the fake one.  On the way up, the
 544  * packet would pass through PRE_ROUTING again (which already
 545  * took place when the packet entered the bridge), but we
 546  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 547  * prevent this from happening. */
 548 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
 549                                    const struct net_device *in,
 550                                    const struct net_device *out,
 551                                    int (*okfn)(struct sk_buff *))
 552 {
 553         struct sk_buff *skb = *pskb;
 554
 555         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 556                 dst_release(skb->dst);
 557                 skb->dst = NULL;
 558         }
 559
 560         return NF_ACCEPT;
 561 }
 562
 563 /* PF_BRIDGE/FORWARD *************************************************/
 564 static int br_nf_forward_finish(struct sk_buff *skb)
 565 {
 566         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 567         struct net_device *in;
 568
 569         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 570                 in = nf_bridge->physindev;
 571                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 572                         skb->pkt_type = PACKET_OTHERHOST;
 573                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 574                 }
 575         } else {
 576                 in = *((struct net_device **)(skb->cb));
 577         }
 578         if (skb->protocol == htons(ETH_P_8021Q)) {
 579                 skb_push(skb, VLAN_HLEN);
 580                 skb->nh.raw -= VLAN_HLEN;
 581         }
 582         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 583                        skb->dev, br_forward_finish, 1);
 584         return 0;
 585 }
 586
 587 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 588  * netfilter with indev and outdev set to the bridge device,
 589  * but we are still able to filter on the 'real' indev/outdev
 590  * because of the physdev module. For ARP, indev and outdev are the
 591  * bridge ports. */
 592 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
 593                                      const struct net_device *in,
 594                                      const struct net_device *out,
 595                                      int (*okfn)(struct sk_buff *))
 596 {
 597         struct sk_buff *skb = *pskb;
 598         struct nf_bridge_info *nf_bridge;
 599         struct net_device *parent;
 600         int pf;
 601
 602         if (!skb->nf_bridge)
 603                 return NF_ACCEPT;
 604
 605         parent = bridge_parent(out);
 606         if (!parent)
 607                 return NF_DROP;
 608
 609         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 610                 pf = PF_INET;
 611         else
 612                 pf = PF_INET6;
 613
 614         if (skb->protocol == htons(ETH_P_8021Q)) {
 615                 skb_pull(*pskb, VLAN_HLEN);
 616                 (*pskb)->nh.raw += VLAN_HLEN;
 617         }
 618
 619         nf_bridge = skb->nf_bridge;
 620         if (skb->pkt_type == PACKET_OTHERHOST) {
 621                 skb->pkt_type = PACKET_HOST;
 622                 nf_bridge->mask |= BRNF_PKT_TYPE;
 623         }
 624
 625         /* The physdev module checks on this */
 626         nf_bridge->mask |= BRNF_BRIDGED;
 627         nf_bridge->physoutdev = skb->dev;
 628
 629         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
 630                 br_nf_forward_finish);
 631
 632         return NF_STOLEN;
 633 }
 634
 635 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
 636                                       const struct net_device *in,
 637                                       const struct net_device *out,
 638                                       int (*okfn)(struct sk_buff *))
 639 {
 640         struct sk_buff *skb = *pskb;
 641         struct net_device **d = (struct net_device **)(skb->cb);
 642
 643 #ifdef CONFIG_SYSCTL
 644         if (!brnf_call_arptables)
 645                 return NF_ACCEPT;
 646 #endif
 647
 648         if (skb->protocol != htons(ETH_P_ARP)) {
 649                 if (!IS_VLAN_ARP(skb))
 650                         return NF_ACCEPT;
 651                 skb_pull(*pskb, VLAN_HLEN);
 652                 (*pskb)->nh.raw += VLAN_HLEN;
 653         }
 654
 655         if (skb->nh.arph->ar_pln != 4) {
 656                 if (IS_VLAN_ARP(skb)) {
 657                         skb_push(*pskb, VLAN_HLEN);
 658                         (*pskb)->nh.raw -= VLAN_HLEN;
 659                 }
 660                 return NF_ACCEPT;
 661         }
 662         *d = (struct net_device *)in;
 663         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 664                 (struct net_device *)out, br_nf_forward_finish);
 665
 666         return NF_STOLEN;
 667 }
 668
 669 /* PF_BRIDGE/LOCAL_OUT ***********************************************/
 670 static int br_nf_local_out_finish(struct sk_buff *skb)
 671 {
 672         if (skb->protocol == htons(ETH_P_8021Q)) {
 673                 skb_push(skb, VLAN_HLEN);
 674                 skb->nh.raw -= VLAN_HLEN;
 675         }
 676
 677         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 678                        br_forward_finish, NF_BR_PRI_FIRST + 1);
 679
 680         return 0;
 681 }
 682
 683 /* This function sees both locally originated IP packets and forwarded
 684  * IP packets (in both cases the destination device is a bridge
 685  * device). It also sees bridged-and-DNAT'ed packets.
 686  * To be able to filter on the physical bridge devices (with the physdev
 687  * module), we steal packets destined to a bridge device away from the
 688  * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
 689  * when we have determined the real output device. This is done in here.
 690  *
 691  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 692  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 693  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 694  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 695  * will be executed.
 696  * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
 697  * this packet before, and so the packet was locally originated. We fake
 698  * the PF_INET/LOCAL_OUT hook.
 699  * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
 700  * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
 701  * even routed packets that didn't arrive on a bridge interface have their
 702  * nf_bridge->physindev set. */
 703 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
 704                                     const struct net_device *in,
 705                                     const struct net_device *out,
 706                                     int (*okfn)(struct sk_buff *))
 707 {
 708         struct net_device *realindev, *realoutdev;
 709         struct sk_buff *skb = *pskb;
 710         struct nf_bridge_info *nf_bridge;
 711         int pf;
 712
 713         if (!skb->nf_bridge)
 714                 return NF_ACCEPT;
 715
 716         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 717                 pf = PF_INET;
 718         else
 719                 pf = PF_INET6;
 720
 721 #ifdef CONFIG_NETFILTER_DEBUG
 722         /* Sometimes we get packets with NULL ->dst here (for example,
 723          * running a dhcp client daemon triggers this). This should now
 724          * be fixed, but let's keep the check around. */
 725         if (skb->dst == NULL) {
 726                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 727                 return NF_ACCEPT;
 728         }
 729 #endif
 730
 731         nf_bridge = skb->nf_bridge;
 732         nf_bridge->physoutdev = skb->dev;
 733         realindev = nf_bridge->physindev;
 734
 735         /* Bridged, take PF_BRIDGE/FORWARD.
 736          * (see big note in front of br_nf_pre_routing_finish) */
 737         if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
 738                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 739                         skb->pkt_type = PACKET_OTHERHOST;
 740                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 741                 }
 742                 if (skb->protocol == htons(ETH_P_8021Q)) {
 743                         skb_push(skb, VLAN_HLEN);
 744                         skb->nh.raw -= VLAN_HLEN;
 745                 }
 746
 747                 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
 748                         skb->dev, br_forward_finish);
 749                 goto out;
 750         }
 751         realoutdev = bridge_parent(skb->dev);
 752         if (!realoutdev)
 753                 return NF_DROP;
 754
 755 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 756         /* iptables should match -o br0.x */
 757         if (nf_bridge->netoutdev)
 758                 realoutdev = nf_bridge->netoutdev;
 759 #endif
 760         if (skb->protocol == htons(ETH_P_8021Q)) {
 761                 skb_pull(skb, VLAN_HLEN);
 762                 (*pskb)->nh.raw += VLAN_HLEN;
 763         }
 764         /* IP forwarded traffic has a physindev, locally
 765          * generated traffic hasn't. */
 766         if (realindev != NULL) {
 767                 if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT)) {
 768                         struct net_device *parent = bridge_parent(realindev);
 769                         if (parent)
 770                                 realindev = parent;
 771                 }
 772
 773                 NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
 774                                realoutdev, br_nf_local_out_finish,
 775                                NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
 776         } else {
 777                 NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
 778                                realoutdev, br_nf_local_out_finish,
 779                                NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
 780         }
 781
 782 out:
 783         return NF_STOLEN;
 784 }
 785
 786 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 787 {
 788         if (skb->protocol == htons(ETH_P_IP) &&
 789             skb->len > skb->dev->mtu &&
 790             !skb_is_gso(skb))
 791                 return ip_fragment(skb, br_dev_queue_push_xmit);
 792         else
 793                 return br_dev_queue_push_xmit(skb);
 794 }
 795
 796 /* PF_BRIDGE/POST_ROUTING ********************************************/
 797 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
 798                                        const struct net_device *in,
 799                                        const struct net_device *out,
 800                                        int (*okfn)(struct sk_buff *))
 801 {
 802         struct sk_buff *skb = *pskb;
 803         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
 804         struct net_device *realoutdev = bridge_parent(skb->dev);
 805         int pf;
 806
 807 #ifdef CONFIG_NETFILTER_DEBUG
 808         /* Be very paranoid. This probably won't happen anymore, but let's
 809          * keep the check just to be sure... */
 810         if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
 811                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 812                        "bad mac.raw pointer.");
 813                 goto print_error;
 814         }
 815 #endif
 816
 817         if (!nf_bridge)
 818                 return NF_ACCEPT;
 819
 820         if (!realoutdev)
 821                 return NF_DROP;
 822
 823         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 824                 pf = PF_INET;
 825         else
 826                 pf = PF_INET6;
 827
 828 #ifdef CONFIG_NETFILTER_DEBUG
 829         if (skb->dst == NULL) {
 830                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 831                 goto print_error;
 832         }
 833 #endif
 834
 835         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 836          * about the value of skb->pkt_type. */
 837         if (skb->pkt_type == PACKET_OTHERHOST) {
 838                 skb->pkt_type = PACKET_HOST;
 839                 nf_bridge->mask |= BRNF_PKT_TYPE;
 840         }
 841
 842         if (skb->protocol == htons(ETH_P_8021Q)) {
 843                 skb_pull(skb, VLAN_HLEN);
 844                 skb->nh.raw += VLAN_HLEN;
 845         }
 846
 847         nf_bridge_save_header(skb);
 848
 849 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 850         if (nf_bridge->netoutdev)
 851                 realoutdev = nf_bridge->netoutdev;
 852 #endif
 853         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
 854                 br_nf_dev_queue_xmit);
 855
 856         return NF_STOLEN;
 857
 858 #ifdef CONFIG_NETFILTER_DEBUG
 859 print_error:
 860         if (skb->dev != NULL) {
 861                 printk("[%s]", skb->dev->name);
 862                 if (realoutdev)
 863                         printk("[%s]", realoutdev->name);
 864         }
 865         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
 866                skb->data);
 867         return NF_ACCEPT;
 868 #endif
 869 }
 870
 871 /* IP/SABOTAGE *****************************************************/
 872 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 873  * for the second time. */
 874 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
 875                                    const struct net_device *in,
 876                                    const struct net_device *out,
 877                                    int (*okfn)(struct sk_buff *))
 878 {
 879         if ((*pskb)->nf_bridge &&
 880             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 881                 return NF_STOP;
 882         }
 883
 884         return NF_ACCEPT;
 885 }
 886
 887 /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
 888  * and PF_INET(6)/POST_ROUTING until we have done the forwarding
 889  * decision in the bridge code and have determined nf_bridge->physoutdev. */
 890 static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 891                                     const struct net_device *in,
 892                                     const struct net_device *out,
 893                                     int (*okfn)(struct sk_buff *))
 894 {
 895         struct sk_buff *skb = *pskb;
 896
 897         if ((out->hard_start_xmit == br_dev_xmit &&
 898              okfn != br_nf_forward_finish &&
 899              okfn != br_nf_local_out_finish && okfn != br_nf_dev_queue_xmit)
 900 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 901             || ((out->priv_flags & IFF_802_1Q_VLAN) &&
 902                 VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
 903 #endif
 904             ) {
 905                 struct nf_bridge_info *nf_bridge;
 906
 907                 if (!skb->nf_bridge) {
 908 #ifdef CONFIG_SYSCTL
 909                         /* This code is executed while in the IP(v6) stack,
 910                            the version should be 4 or 6. We can't use
 911                            skb->protocol because that isn't set on
 912                            PF_INET(6)/LOCAL_OUT. */
 913                         struct iphdr *ip = skb->nh.iph;
 914
 915                         if (ip->version == 4 && !brnf_call_iptables)
 916                                 return NF_ACCEPT;
 917                         else if (ip->version == 6 && !brnf_call_ip6tables)
 918                                 return NF_ACCEPT;
 919                         else if (!brnf_deferred_hooks)
 920                                 return NF_ACCEPT;
 921 #endif
 922                         if (hook == NF_IP_POST_ROUTING)
 923                                 return NF_ACCEPT;
 924                         if (!nf_bridge_alloc(skb))
 925                                 return NF_DROP;
 926                 }
 927
 928                 nf_bridge = skb->nf_bridge;
 929
 930                 /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
 931                  * will need the indev then. For a brouter, the real indev
 932                  * can be a bridge port, so we make sure br_nf_local_out()
 933                  * doesn't use the bridge parent of the indev by using
 934                  * the BRNF_DONT_TAKE_PARENT mask. */
 935                 if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
 936                         nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
 937                         nf_bridge->physindev = (struct net_device *)in;
 938                 }
 939 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 940                 /* the iptables outdev is br0.x, not br0 */
 941                 if (out->priv_flags & IFF_802_1Q_VLAN)
 942                         nf_bridge->netoutdev = (struct net_device *)out;
 943 #endif
 944                 return NF_STOP;
 945         }
 946
 947         return NF_ACCEPT;
 948 }
 949
 950 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 951  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 952  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 953  * ip_refrag() can return NF_STOLEN. */
 954 static struct nf_hook_ops br_nf_ops[] = {
 955         { .hook = br_nf_pre_routing,
 956           .owner = THIS_MODULE,
 957           .pf = PF_BRIDGE,
 958           .hooknum = NF_BR_PRE_ROUTING,
 959           .priority = NF_BR_PRI_BRNF, },
 960         { .hook = br_nf_local_in,
 961           .owner = THIS_MODULE,
 962           .pf = PF_BRIDGE,
 963           .hooknum = NF_BR_LOCAL_IN,
 964           .priority = NF_BR_PRI_BRNF, },
 965         { .hook = br_nf_forward_ip,
 966           .owner = THIS_MODULE,
 967           .pf = PF_BRIDGE,
 968           .hooknum = NF_BR_FORWARD,
 969           .priority = NF_BR_PRI_BRNF - 1, },
 970         { .hook = br_nf_forward_arp,
 971           .owner = THIS_MODULE,
 972           .pf = PF_BRIDGE,
 973           .hooknum = NF_BR_FORWARD,
 974           .priority = NF_BR_PRI_BRNF, },
 975         { .hook = br_nf_local_out,
 976           .owner = THIS_MODULE,
 977           .pf = PF_BRIDGE,
 978           .hooknum = NF_BR_LOCAL_OUT,
 979           .priority = NF_BR_PRI_FIRST, },
 980         { .hook = br_nf_post_routing,
 981           .owner = THIS_MODULE,
 982           .pf = PF_BRIDGE,
 983           .hooknum = NF_BR_POST_ROUTING,
 984           .priority = NF_BR_PRI_LAST, },
 985         { .hook = ip_sabotage_in,
 986           .owner = THIS_MODULE,
 987           .pf = PF_INET,
 988           .hooknum = NF_IP_PRE_ROUTING,
 989           .priority = NF_IP_PRI_FIRST, },
 990         { .hook = ip_sabotage_in,
 991           .owner = THIS_MODULE,
 992           .pf = PF_INET6,
 993           .hooknum = NF_IP6_PRE_ROUTING,
 994           .priority = NF_IP6_PRI_FIRST, },
 995         { .hook = ip_sabotage_out,
 996           .owner = THIS_MODULE,
 997           .pf = PF_INET,
 998           .hooknum = NF_IP_FORWARD,
 999           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
1000         { .hook = ip_sabotage_out,
1001           .owner = THIS_MODULE,
1002           .pf = PF_INET6,
1003           .hooknum = NF_IP6_FORWARD,
1004           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
1005         { .hook = ip_sabotage_out,
1006           .owner = THIS_MODULE,
1007           .pf = PF_INET,
1008           .hooknum = NF_IP_LOCAL_OUT,
1009           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
1010         { .hook = ip_sabotage_out,
1011           .owner = THIS_MODULE,
1012           .pf = PF_INET6,
1013           .hooknum = NF_IP6_LOCAL_OUT,
1014           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
1015         { .hook = ip_sabotage_out,
1016           .owner = THIS_MODULE,
1017           .pf = PF_INET,
1018           .hooknum = NF_IP_POST_ROUTING,
1019           .priority = NF_IP_PRI_FIRST, },
1020         { .hook = ip_sabotage_out,
1021           .owner = THIS_MODULE,
1022           .pf = PF_INET6,
1023           .hooknum = NF_IP6_POST_ROUTING,
1024           .priority = NF_IP6_PRI_FIRST, },
1025 };
1026
1027 #ifdef CONFIG_SYSCTL
1028 static
1029 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
1030                             void __user * buffer, size_t * lenp, loff_t * ppos)
1031 {
1032         int ret;
1033
1034         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
1035
1036         if (write && *(int *)(ctl->data))
1037                 *(int *)(ctl->data) = 1;
1038         return ret;
1039 }
1040
1041 static ctl_table brnf_table[] = {
1042         {
1043                 .ctl_name       = NET_BRIDGE_NF_CALL_ARPTABLES,
1044                 .procname       = "bridge-nf-call-arptables",
1045                 .data           = &brnf_call_arptables,
1046                 .maxlen         = sizeof(int),
1047                 .mode           = 0644,
1048                 .proc_handler   = &brnf_sysctl_call_tables,
1049         },
1050         {
1051                 .ctl_name       = NET_BRIDGE_NF_CALL_IPTABLES,
1052                 .procname       = "bridge-nf-call-iptables",
1053                 .data           = &brnf_call_iptables,
1054                 .maxlen         = sizeof(int),
1055                 .mode           = 0644,
1056                 .proc_handler   = &brnf_sysctl_call_tables,
1057         },
1058         {
1059                 .ctl_name       = NET_BRIDGE_NF_CALL_IP6TABLES,
1060                 .procname       = "bridge-nf-call-ip6tables",
1061                 .data           = &brnf_call_ip6tables,
1062                 .maxlen         = sizeof(int),
1063                 .mode           = 0644,
1064                 .proc_handler   = &brnf_sysctl_call_tables,
1065         },
1066         {
1067                 .ctl_name       = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
1068                 .procname       = "bridge-nf-filter-vlan-tagged",
1069                 .data           = &brnf_filter_vlan_tagged,
1070                 .maxlen         = sizeof(int),
1071                 .mode           = 0644,
1072                 .proc_handler   = &brnf_sysctl_call_tables,
1073         },
1074         { .ctl_name = 0 }
1075 };
1076
1077 static ctl_table brnf_bridge_table[] = {
1078         {
1079                 .ctl_name       = NET_BRIDGE,
1080                 .procname       = "bridge",
1081                 .mode           = 0555,
1082                 .child          = brnf_table,
1083         },
1084         { .ctl_name = 0 }
1085 };
1086
1087 static ctl_table brnf_net_table[] = {
1088         {
1089                 .ctl_name       = CTL_NET,
1090                 .procname       = "net",
1091                 .mode           = 0555,
1092                 .child          = brnf_bridge_table,
1093         },
1094         { .ctl_name = 0 }
1095 };
1096 #endif
1097
1098 int br_netfilter_init(void)
1099 {
1100         int i;
1101
1102         for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
1103                 int ret;
1104
1105                 if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
1106                         continue;
1107
1108                 while (i--)
1109                         nf_unregister_hook(&br_nf_ops[i]);
1110
1111                 return ret;
1112         }
1113
1114 #ifdef CONFIG_SYSCTL
1115         brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
1116         if (brnf_sysctl_header == NULL) {
1117                 printk(KERN_WARNING
1118                        "br_netfilter: can't register to sysctl.\n");
1119                 for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
1120                         nf_unregister_hook(&br_nf_ops[i]);
1121                 return -EFAULT;
1122         }
1123 #endif
1124
1125         printk(KERN_NOTICE "Bridge firewalling registered\n");
1126
1127         return 0;
1128 }
1129
1130 void br_netfilter_fini(void)
1131 {
1132         int i;
1133
1134         for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
1135                 nf_unregister_hook(&br_nf_ops[i]);
1136 #ifdef CONFIG_SYSCTL
1137         unregister_sysctl_table(brnf_sysctl_header);
1138 #endif
1139 }