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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,
 222                     dev)) {
 223                         struct rtable *rt;
 224                         struct flowi fl = { .nl_u =
 225                         { .ip4_u = { .daddr = iph->daddr, .saddr = 0 ,
 226                                      .tos = RT_TOS(iph->tos)} }, .proto = 0};
 227
 228                         if (!ip_route_output_key(&rt, &fl)) {
 229                                 /* - Bridged-and-DNAT'ed traffic doesn't
 230                                  *   require ip_forwarding.
 231                                  * - Deal with redirected traffic. */
 232                                 if (((struct dst_entry *)rt)->dev == dev ||
 233                                     rt->rt_type == RTN_LOCAL) {
 234                                         skb->dst = (struct dst_entry *)rt;
 235                                         goto bridged_dnat;
 236                                 }
 237                                 __br_dnat_complain();
 238                                 dst_release((struct dst_entry *)rt);
 239                         }
 240                         kfree_skb(skb);
 241                         return 0;
 242                 } else {
 243                         if (skb->dst->dev == dev) {
 244 bridged_dnat:
 245                                 /* Tell br_nf_local_out this is a
 246                                  * bridged frame */
 247                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 248                                 skb->dev = nf_bridge->physindev;
 249                                 if (skb->protocol ==
 250                                     __constant_htons(ETH_P_8021Q)) {
 251                                         skb_push(skb, VLAN_HLEN);
 252                                         skb->nh.raw -= VLAN_HLEN;
 253                                 }
 254                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 255                                                skb, skb->dev, NULL,
 256                                                br_nf_pre_routing_finish_bridge,
 257                                                1);
 258                                 return 0;
 259                         }
 260                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr,
 261                                ETH_ALEN);
 262                         skb->pkt_type = PACKET_HOST;
 263                 }
 264         } else {
 265                 skb->dst = (struct dst_entry *)&__fake_rtable;
 266                 dst_hold(skb->dst);
 267         }
 268
 269         skb->dev = nf_bridge->physindev;
 270         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 271                 skb_push(skb, VLAN_HLEN);
 272                 skb->nh.raw -= VLAN_HLEN;
 273         }
 274         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 275                        br_handle_frame_finish, 1);
 276
 277         return 0;
 278 }
 279
 280 /* Some common code for IPv4/IPv6 */
 281 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 282 {
 283         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 284
 285         if (skb->pkt_type == PACKET_OTHERHOST) {
 286                 skb->pkt_type = PACKET_HOST;
 287                 nf_bridge->mask |= BRNF_PKT_TYPE;
 288         }
 289
 290         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 291         nf_bridge->physindev = skb->dev;
 292         skb->dev = bridge_parent(skb->dev);
 293
 294         return skb->dev;
 295 }
 296
 297 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 298 static int check_hbh_len(struct sk_buff *skb)
 299 {
 300         unsigned char *raw = (u8*)(skb->nh.ipv6h+1);
 301         u32 pkt_len;
 302         int off = raw - skb->nh.raw;
 303         int len = (raw[1]+1)<<3;
 304
 305         if ((raw + len) - skb->data > skb_headlen(skb))
 306                 goto bad;
 307
 308         off += 2;
 309         len -= 2;
 310
 311         while (len > 0) {
 312                 int optlen = skb->nh.raw[off+1]+2;
 313
 314                 switch (skb->nh.raw[off]) {
 315                 case IPV6_TLV_PAD0:
 316                         optlen = 1;
 317                         break;
 318
 319                 case IPV6_TLV_PADN:
 320                         break;
 321
 322                 case IPV6_TLV_JUMBO:
 323                         if (skb->nh.raw[off+1] != 4 || (off&3) != 2)
 324                                 goto bad;
 325                         pkt_len = ntohl(*(u32*)(skb->nh.raw+off+2));
 326                         if (pkt_len <= IPV6_MAXPLEN ||
 327                             skb->nh.ipv6h->payload_len)
 328                                 goto bad;
 329                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 330                                 goto bad;
 331                         if (pskb_trim_rcsum(skb,
 332                             pkt_len+sizeof(struct ipv6hdr)))
 333                                 goto bad;
 334                         break;
 335                 default:
 336                         if (optlen > len)
 337                                 goto bad;
 338                         break;
 339                 }
 340                 off += optlen;
 341                 len -= optlen;
 342         }
 343         if (len == 0)
 344                 return 0;
 345 bad:
 346         return -1;
 347
 348 }
 349
 350 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 351  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 352 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 353    struct sk_buff *skb, const struct net_device *in,
 354    const struct net_device *out, int (*okfn)(struct sk_buff *))
 355 {
 356         struct ipv6hdr *hdr;
 357         u32 pkt_len;
 358         struct nf_bridge_info *nf_bridge;
 359
 360         if (skb->len < sizeof(struct ipv6hdr))
 361                 goto inhdr_error;
 362
 363         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 364                 goto inhdr_error;
 365
 366         hdr = skb->nh.ipv6h;
 367
 368         if (hdr->version != 6)
 369                 goto inhdr_error;
 370
 371         pkt_len = ntohs(hdr->payload_len);
 372
 373         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 374                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 375                         goto inhdr_error;
 376                 if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
 377                         if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr)))
 378                                 goto inhdr_error;
 379                         if (skb->ip_summed == CHECKSUM_HW)
 380                                 skb->ip_summed = CHECKSUM_NONE;
 381                 }
 382         }
 383         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 384                         goto inhdr_error;
 385
 386         nf_bridge_put(skb->nf_bridge);
 387         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 388                 return NF_DROP;
 389         if (!setup_pre_routing(skb))
 390                 return NF_DROP;
 391
 392         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 393                 br_nf_pre_routing_finish_ipv6);
 394
 395         return NF_STOLEN;
 396
 397 inhdr_error:
 398         return NF_DROP;
 399 }
 400
 401 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 402  * Replicate the checks that IPv4 does on packet reception.
 403  * Set skb->dev to the bridge device (i.e. parent of the
 404  * receiving device) to make netfilter happy, the REDIRECT
 405  * target in particular.  Save the original destination IP
 406  * address to be able to detect DNAT afterwards. */
 407 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 408                                       const struct net_device *in,
 409                                       const struct net_device *out,
 410                                       int (*okfn)(struct sk_buff *))
 411 {
 412         struct iphdr *iph;
 413         __u32 len;
 414         struct sk_buff *skb = *pskb;
 415         struct nf_bridge_info *nf_bridge;
 416         struct vlan_ethhdr *hdr = vlan_eth_hdr(*pskb);
 417
 418         if (skb->protocol == __constant_htons(ETH_P_IPV6) || IS_VLAN_IPV6) {
 419 #ifdef CONFIG_SYSCTL
 420                 if (!brnf_call_ip6tables)
 421                         return NF_ACCEPT;
 422 #endif
 423                 if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 424                         goto out;
 425
 426                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 427                         u8 *vhdr = skb->data;
 428                         skb_pull(skb, VLAN_HLEN);
 429                         skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
 430                         skb->nh.raw += VLAN_HLEN;
 431                 }
 432                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 433         }
 434 #ifdef CONFIG_SYSCTL
 435         if (!brnf_call_iptables)
 436                 return NF_ACCEPT;
 437 #endif
 438
 439         if (skb->protocol != __constant_htons(ETH_P_IP) && !IS_VLAN_IP)
 440                 return NF_ACCEPT;
 441
 442         if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 443                 goto out;
 444
 445         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 446                 u8 *vhdr = skb->data;
 447                 skb_pull(skb, VLAN_HLEN);
 448                 skb_postpull_rcsum(skb, vhdr, VLAN_HLEN);
 449                 skb->nh.raw += VLAN_HLEN;
 450         }
 451
 452         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 453                 goto inhdr_error;
 454
 455         iph = skb->nh.iph;
 456         if (iph->ihl < 5 || iph->version != 4)
 457                 goto inhdr_error;
 458
 459         if (!pskb_may_pull(skb, 4*iph->ihl))
 460                 goto inhdr_error;
 461
 462         iph = skb->nh.iph;
 463         if (ip_fast_csum((__u8 *)iph, iph->ihl) != 0)
 464                 goto inhdr_error;
 465
 466         len = ntohs(iph->tot_len);
 467         if (skb->len < len || len < 4*iph->ihl)
 468                 goto inhdr_error;
 469
 470         if (skb->len > len) {
 471                 __pskb_trim(skb, len);
 472                 if (skb->ip_summed == CHECKSUM_HW)
 473                         skb->ip_summed = CHECKSUM_NONE;
 474         }
 475
 476         nf_bridge_put(skb->nf_bridge);
 477         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 478                 return NF_DROP;
 479         if (!setup_pre_routing(skb))
 480                 return NF_DROP;
 481         store_orig_dstaddr(skb);
 482
 483         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 484                 br_nf_pre_routing_finish);
 485
 486         return NF_STOLEN;
 487
 488 inhdr_error:
 489 //      IP_INC_STATS_BH(IpInHdrErrors);
 490 out:
 491         return NF_DROP;
 492 }
 493
 494
 495 /* PF_BRIDGE/LOCAL_IN ************************************************/
 496 /* The packet is locally destined, which requires a real
 497  * dst_entry, so detach the fake one.  On the way up, the
 498  * packet would pass through PRE_ROUTING again (which already
 499  * took place when the packet entered the bridge), but we
 500  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 501  * prevent this from happening. */
 502 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
 503    const struct net_device *in, const struct net_device *out,
 504    int (*okfn)(struct sk_buff *))
 505 {
 506         struct sk_buff *skb = *pskb;
 507
 508         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 509                 dst_release(skb->dst);
 510                 skb->dst = NULL;
 511         }
 512
 513         return NF_ACCEPT;
 514 }
 515
 516
 517 /* PF_BRIDGE/FORWARD *************************************************/
 518 static int br_nf_forward_finish(struct sk_buff *skb)
 519 {
 520         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 521         struct net_device *in;
 522         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 523
 524         if (skb->protocol != __constant_htons(ETH_P_ARP) && !IS_VLAN_ARP) {
 525                 in = nf_bridge->physindev;
 526                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 527                         skb->pkt_type = PACKET_OTHERHOST;
 528                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 529                 }
 530         } else {
 531                 in = *((struct net_device **)(skb->cb));
 532         }
 533         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 534                 skb_push(skb, VLAN_HLEN);
 535                 skb->nh.raw -= VLAN_HLEN;
 536         }
 537         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 538                         skb->dev, br_forward_finish, 1);
 539         return 0;
 540 }
 541
 542 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 543  * netfilter with indev and outdev set to the bridge device,
 544  * but we are still able to filter on the 'real' indev/outdev
 545  * because of the physdev module. For ARP, indev and outdev are the
 546  * bridge ports. */
 547 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
 548    const struct net_device *in, const struct net_device *out,
 549    int (*okfn)(struct sk_buff *))
 550 {
 551         struct sk_buff *skb = *pskb;
 552         struct nf_bridge_info *nf_bridge;
 553         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 554         struct net_device *parent;
 555         int pf;
 556
 557         if (!skb->nf_bridge)
 558                 return NF_ACCEPT;
 559
 560         parent = bridge_parent(out);
 561         if (!parent)
 562                 return NF_DROP;
 563
 564         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 565                 pf = PF_INET;
 566         else
 567                 pf = PF_INET6;
 568
 569         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 570                 skb_pull(*pskb, VLAN_HLEN);
 571                 (*pskb)->nh.raw += VLAN_HLEN;
 572         }
 573
 574         nf_bridge = skb->nf_bridge;
 575         if (skb->pkt_type == PACKET_OTHERHOST) {
 576                 skb->pkt_type = PACKET_HOST;
 577                 nf_bridge->mask |= BRNF_PKT_TYPE;
 578         }
 579
 580         /* The physdev module checks on this */
 581         nf_bridge->mask |= BRNF_BRIDGED;
 582         nf_bridge->physoutdev = skb->dev;
 583
 584         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
 585                 br_nf_forward_finish);
 586
 587         return NF_STOLEN;
 588 }
 589
 590 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
 591    const struct net_device *in, const struct net_device *out,
 592    int (*okfn)(struct sk_buff *))
 593 {
 594         struct sk_buff *skb = *pskb;
 595         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 596         struct net_device **d = (struct net_device **)(skb->cb);
 597
 598 #ifdef CONFIG_SYSCTL
 599         if (!brnf_call_arptables)
 600                 return NF_ACCEPT;
 601 #endif
 602
 603         if (skb->protocol != __constant_htons(ETH_P_ARP)) {
 604                 if (!IS_VLAN_ARP)
 605                         return NF_ACCEPT;
 606                 skb_pull(*pskb, VLAN_HLEN);
 607                 (*pskb)->nh.raw += VLAN_HLEN;
 608         }
 609
 610         if (skb->nh.arph->ar_pln != 4) {
 611                 if (IS_VLAN_ARP) {
 612                         skb_push(*pskb, VLAN_HLEN);
 613                         (*pskb)->nh.raw -= VLAN_HLEN;
 614                 }
 615                 return NF_ACCEPT;
 616         }
 617         *d = (struct net_device *)in;
 618         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 619                 (struct net_device *)out, br_nf_forward_finish);
 620
 621         return NF_STOLEN;
 622 }
 623
 624
 625 /* PF_BRIDGE/LOCAL_OUT ***********************************************/
 626 static int br_nf_local_out_finish(struct sk_buff *skb)
 627 {
 628         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 629                 skb_push(skb, VLAN_HLEN);
 630                 skb->nh.raw -= VLAN_HLEN;
 631         }
 632
 633         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 634                         br_forward_finish, NF_BR_PRI_FIRST + 1);
 635
 636         return 0;
 637 }
 638
 639 /* This function sees both locally originated IP packets and forwarded
 640  * IP packets (in both cases the destination device is a bridge
 641  * device). It also sees bridged-and-DNAT'ed packets.
 642  * To be able to filter on the physical bridge devices (with the physdev
 643  * module), we steal packets destined to a bridge device away from the
 644  * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
 645  * when we have determined the real output device. This is done in here.
 646  *
 647  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 648  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 649  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 650  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 651  * will be executed.
 652  * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
 653  * this packet before, and so the packet was locally originated. We fake
 654  * the PF_INET/LOCAL_OUT hook.
 655  * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
 656  * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
 657  * even routed packets that didn't arrive on a bridge interface have their
 658  * nf_bridge->physindev set. */
 659 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
 660    const struct net_device *in, const struct net_device *out,
 661    int (*okfn)(struct sk_buff *))
 662 {
 663         struct net_device *realindev, *realoutdev;
 664         struct sk_buff *skb = *pskb;
 665         struct nf_bridge_info *nf_bridge;
 666         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 667         int pf;
 668
 669         if (!skb->nf_bridge)
 670                 return NF_ACCEPT;
 671
 672         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 673                 pf = PF_INET;
 674         else
 675                 pf = PF_INET6;
 676
 677 #ifdef CONFIG_NETFILTER_DEBUG
 678         /* Sometimes we get packets with NULL ->dst here (for example,
 679          * running a dhcp client daemon triggers this). This should now
 680          * be fixed, but let's keep the check around. */
 681         if (skb->dst == NULL) {
 682                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 683                 return NF_ACCEPT;
 684         }
 685 #endif
 686
 687         nf_bridge = skb->nf_bridge;
 688         nf_bridge->physoutdev = skb->dev;
 689         realindev = nf_bridge->physindev;
 690
 691         /* Bridged, take PF_BRIDGE/FORWARD.
 692          * (see big note in front of br_nf_pre_routing_finish) */
 693         if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
 694                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 695                         skb->pkt_type = PACKET_OTHERHOST;
 696                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 697                 }
 698                 if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 699                         skb_push(skb, VLAN_HLEN);
 700                         skb->nh.raw -= VLAN_HLEN;
 701                 }
 702
 703                 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
 704                         skb->dev, br_forward_finish);
 705                 goto out;
 706         }
 707         realoutdev = bridge_parent(skb->dev);
 708         if (!realoutdev)
 709                 return NF_DROP;
 710
 711 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 712         /* iptables should match -o br0.x */
 713         if (nf_bridge->netoutdev)
 714                 realoutdev = nf_bridge->netoutdev;
 715 #endif
 716         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 717                 skb_pull(skb, VLAN_HLEN);
 718                 (*pskb)->nh.raw += VLAN_HLEN;
 719         }
 720         /* IP forwarded traffic has a physindev, locally
 721          * generated traffic hasn't. */
 722         if (realindev != NULL) {
 723                 if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) ) {
 724                         struct net_device *parent = bridge_parent(realindev);
 725                         if (parent)
 726                                 realindev = parent;
 727                 }
 728
 729                 NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
 730                                realoutdev, br_nf_local_out_finish,
 731                                NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
 732         } else {
 733                 NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
 734                                realoutdev, br_nf_local_out_finish,
 735                                NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
 736         }
 737
 738 out:
 739         return NF_STOLEN;
 740 }
 741
 742
 743 /* PF_BRIDGE/POST_ROUTING ********************************************/
 744 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
 745    const struct net_device *in, const struct net_device *out,
 746    int (*okfn)(struct sk_buff *))
 747 {
 748         struct sk_buff *skb = *pskb;
 749         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
 750         struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
 751         struct net_device *realoutdev = bridge_parent(skb->dev);
 752         int pf;
 753
 754 #ifdef CONFIG_NETFILTER_DEBUG
 755         /* Be very paranoid. This probably won't happen anymore, but let's
 756          * keep the check just to be sure... */
 757         if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
 758                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 759                                  "bad mac.raw pointer.");
 760                 goto print_error;
 761         }
 762 #endif
 763
 764         if (!nf_bridge)
 765                 return NF_ACCEPT;
 766
 767         if (!realoutdev)
 768                 return NF_DROP;
 769
 770         if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
 771                 pf = PF_INET;
 772         else
 773                 pf = PF_INET6;
 774
 775 #ifdef CONFIG_NETFILTER_DEBUG
 776         if (skb->dst == NULL) {
 777                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 778                 goto print_error;
 779         }
 780 #endif
 781
 782         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 783          * about the value of skb->pkt_type. */
 784         if (skb->pkt_type == PACKET_OTHERHOST) {
 785                 skb->pkt_type = PACKET_HOST;
 786                 nf_bridge->mask |= BRNF_PKT_TYPE;
 787         }
 788
 789         if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
 790                 skb_pull(skb, VLAN_HLEN);
 791                 skb->nh.raw += VLAN_HLEN;
 792         }
 793
 794         nf_bridge_save_header(skb);
 795
 796 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 797         if (nf_bridge->netoutdev)
 798                 realoutdev = nf_bridge->netoutdev;
 799 #endif
 800         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
 801                 br_dev_queue_push_xmit);
 802
 803         return NF_STOLEN;
 804
 805 #ifdef CONFIG_NETFILTER_DEBUG
 806 print_error:
 807         if (skb->dev != NULL) {
 808                 printk("[%s]", skb->dev->name);
 809                 if (realoutdev)
 810                         printk("[%s]", realoutdev->name);
 811         }
 812         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
 813                                               skb->data);
 814         return NF_ACCEPT;
 815 #endif
 816 }
 817
 818
 819 /* IP/SABOTAGE *****************************************************/
 820 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 821  * for the second time. */
 822 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
 823    const struct net_device *in, const struct net_device *out,
 824    int (*okfn)(struct sk_buff *))
 825 {
 826         if ((*pskb)->nf_bridge &&
 827             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 828                 return NF_STOP;
 829         }
 830
 831         return NF_ACCEPT;
 832 }
 833
 834 /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
 835  * and PF_INET(6)/POST_ROUTING until we have done the forwarding
 836  * decision in the bridge code and have determined nf_bridge->physoutdev. */
 837 static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 838    const struct net_device *in, const struct net_device *out,
 839    int (*okfn)(struct sk_buff *))
 840 {
 841         struct sk_buff *skb = *pskb;
 842
 843         if ((out->hard_start_xmit == br_dev_xmit &&
 844             okfn != br_nf_forward_finish &&
 845             okfn != br_nf_local_out_finish &&
 846             okfn != br_dev_queue_push_xmit)
 847 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 848             || ((out->priv_flags & IFF_802_1Q_VLAN) &&
 849             VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
 850 #endif
 851             ) {
 852                 struct nf_bridge_info *nf_bridge;
 853
 854                 if (!skb->nf_bridge) {
 855 #ifdef CONFIG_SYSCTL
 856                         /* This code is executed while in the IP(v6) stack,
 857                            the version should be 4 or 6. We can't use
 858                            skb->protocol because that isn't set on
 859                            PF_INET(6)/LOCAL_OUT. */
 860                         struct iphdr *ip = skb->nh.iph;
 861
 862                         if (ip->version == 4 && !brnf_call_iptables)
 863                                 return NF_ACCEPT;
 864                         else if (ip->version == 6 && !brnf_call_ip6tables)
 865                                 return NF_ACCEPT;
 866 #endif
 867                         if (hook == NF_IP_POST_ROUTING)
 868                                 return NF_ACCEPT;
 869                         if (!nf_bridge_alloc(skb))
 870                                 return NF_DROP;
 871                 }
 872
 873                 nf_bridge = skb->nf_bridge;
 874
 875                 /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
 876                  * will need the indev then. For a brouter, the real indev
 877                  * can be a bridge port, so we make sure br_nf_local_out()
 878                  * doesn't use the bridge parent of the indev by using
 879                  * the BRNF_DONT_TAKE_PARENT mask. */
 880                 if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
 881                         nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
 882                         nf_bridge->physindev = (struct net_device *)in;
 883                 }
 884 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 885                 /* the iptables outdev is br0.x, not br0 */
 886                 if (out->priv_flags & IFF_802_1Q_VLAN)
 887                         nf_bridge->netoutdev = (struct net_device *)out;
 888 #endif
 889                 return NF_STOP;
 890         }
 891
 892         return NF_ACCEPT;
 893 }
 894
 895 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 896  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 897  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 898  * ip_refrag() can return NF_STOLEN. */
 899 static struct nf_hook_ops br_nf_ops[] = {
 900         { .hook = br_nf_pre_routing,
 901           .owner = THIS_MODULE,
 902           .pf = PF_BRIDGE,
 903           .hooknum = NF_BR_PRE_ROUTING,
 904           .priority = NF_BR_PRI_BRNF, },
 905         { .hook = br_nf_local_in,
 906           .owner = THIS_MODULE,
 907           .pf = PF_BRIDGE,
 908           .hooknum = NF_BR_LOCAL_IN,
 909           .priority = NF_BR_PRI_BRNF, },
 910         { .hook = br_nf_forward_ip,
 911           .owner = THIS_MODULE,
 912           .pf = PF_BRIDGE,
 913           .hooknum = NF_BR_FORWARD,
 914           .priority = NF_BR_PRI_BRNF - 1, },
 915         { .hook = br_nf_forward_arp,
 916           .owner = THIS_MODULE,
 917           .pf = PF_BRIDGE,
 918           .hooknum = NF_BR_FORWARD,
 919           .priority = NF_BR_PRI_BRNF, },
 920         { .hook = br_nf_local_out,
 921           .owner = THIS_MODULE,
 922           .pf = PF_BRIDGE,
 923           .hooknum = NF_BR_LOCAL_OUT,
 924           .priority = NF_BR_PRI_FIRST, },
 925         { .hook = br_nf_post_routing,
 926           .owner = THIS_MODULE,
 927           .pf = PF_BRIDGE,
 928           .hooknum = NF_BR_POST_ROUTING,
 929           .priority = NF_BR_PRI_LAST, },
 930         { .hook = ip_sabotage_in,
 931           .owner = THIS_MODULE,
 932           .pf = PF_INET,
 933           .hooknum = NF_IP_PRE_ROUTING,
 934           .priority = NF_IP_PRI_FIRST, },
 935         { .hook = ip_sabotage_in,
 936           .owner = THIS_MODULE,
 937           .pf = PF_INET6,
 938           .hooknum = NF_IP6_PRE_ROUTING,
 939           .priority = NF_IP6_PRI_FIRST, },
 940         { .hook = ip_sabotage_out,
 941           .owner = THIS_MODULE,
 942           .pf = PF_INET,
 943           .hooknum = NF_IP_FORWARD,
 944           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
 945         { .hook = ip_sabotage_out,
 946           .owner = THIS_MODULE,
 947           .pf = PF_INET6,
 948           .hooknum = NF_IP6_FORWARD,
 949           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
 950         { .hook = ip_sabotage_out,
 951           .owner = THIS_MODULE,
 952           .pf = PF_INET,
 953           .hooknum = NF_IP_LOCAL_OUT,
 954           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 955         { .hook = ip_sabotage_out,
 956           .owner = THIS_MODULE,
 957           .pf = PF_INET6,
 958           .hooknum = NF_IP6_LOCAL_OUT,
 959           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 960         { .hook = ip_sabotage_out,
 961           .owner = THIS_MODULE,
 962           .pf = PF_INET,
 963           .hooknum = NF_IP_POST_ROUTING,
 964           .priority = NF_IP_PRI_FIRST, },
 965         { .hook = ip_sabotage_out,
 966           .owner = THIS_MODULE,
 967           .pf = PF_INET6,
 968           .hooknum = NF_IP6_POST_ROUTING,
 969           .priority = NF_IP6_PRI_FIRST, },
 970 };
 971
 972 #ifdef CONFIG_SYSCTL
 973 static
 974 int brnf_sysctl_call_tables(ctl_table *ctl, int write, struct file * filp,
 975                         void __user *buffer, size_t *lenp, loff_t *ppos)
 976 {
 977         int ret;
 978
 979         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 980
 981         if (write && *(int *)(ctl->data))
 982                 *(int *)(ctl->data) = 1;
 983         return ret;
 984 }
 985
 986 static ctl_table brnf_table[] = {
 987         {
 988                 .ctl_name       = NET_BRIDGE_NF_CALL_ARPTABLES,
 989                 .procname       = "bridge-nf-call-arptables",
 990                 .data           = &brnf_call_arptables,
 991                 .maxlen         = sizeof(int),
 992                 .mode           = 0644,
 993                 .proc_handler   = &brnf_sysctl_call_tables,
 994         },
 995         {
 996                 .ctl_name       = NET_BRIDGE_NF_CALL_IPTABLES,
 997                 .procname       = "bridge-nf-call-iptables",
 998                 .data           = &brnf_call_iptables,
 999                 .maxlen         = sizeof(int),
1000                 .mode           = 0644,
1001                 .proc_handler   = &brnf_sysctl_call_tables,
1002         },
1003         {
1004                 .ctl_name       = NET_BRIDGE_NF_CALL_IP6TABLES,
1005                 .procname       = "bridge-nf-call-ip6tables",
1006                 .data           = &brnf_call_ip6tables,
1007                 .maxlen         = sizeof(int),
1008                 .mode           = 0644,
1009                 .proc_handler   = &brnf_sysctl_call_tables,
1010         },
1011         {
1012                 .ctl_name       = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
1013                 .procname       = "bridge-nf-filter-vlan-tagged",
1014                 .data           = &brnf_filter_vlan_tagged,
1015                 .maxlen         = sizeof(int),
1016                 .mode           = 0644,
1017                 .proc_handler   = &brnf_sysctl_call_tables,
1018         },
1019         { .ctl_name = 0 }
1020 };
1021
1022 static ctl_table brnf_bridge_table[] = {
1023         {
1024                 .ctl_name       = NET_BRIDGE,
1025                 .procname       = "bridge",
1026                 .mode           = 0555,
1027                 .child          = brnf_table,
1028         },
1029         { .ctl_name = 0 }
1030 };
1031
1032 static ctl_table brnf_net_table[] = {
1033         {
1034                 .ctl_name       = CTL_NET,
1035                 .procname       = "net",
1036                 .mode           = 0555,
1037                 .child          = brnf_bridge_table,
1038         },
1039         { .ctl_name = 0 }
1040 };
1041 #endif
1042
1043 int br_netfilter_init(void)
1044 {
1045         int i;
1046
1047         for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
1048                 int ret;
1049
1050                 if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
1051                         continue;
1052
1053                 while (i--)
1054                         nf_unregister_hook(&br_nf_ops[i]);
1055
1056                 return ret;
1057         }
1058
1059 #ifdef CONFIG_SYSCTL
1060         brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
1061         if (brnf_sysctl_header == NULL) {
1062                 printk(KERN_WARNING "br_netfilter: can't register to sysctl.\n");
1063                 for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
1064                         nf_unregister_hook(&br_nf_ops[i]);
1065                 return -EFAULT;
1066         }
1067 #endif
1068
1069         printk(KERN_NOTICE "Bridge firewalling registered\n");
1070
1071         return 0;
1072 }
1073
1074 void br_netfilter_fini(void)
1075 {
1076         int i;
1077
1078         for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
1079                 nf_unregister_hook(&br_nf_ops[i]);
1080 #ifdef CONFIG_SYSCTL
1081         unregister_sysctl_table(brnf_sysctl_header);
1082 #endif
1083 }