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