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