err.no Git - linux-2.6/blob - 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 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 117 /* Undo the changes made for ip6tables PREROUTING and continue the
 118  * bridge PRE_ROUTING hook. */
 119 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 120 {
 121         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 122
 123         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 124                 skb->pkt_type = PACKET_OTHERHOST;
 125                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 126         }
 127         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 128
 129         skb->dst = (struct dst_entry *)&__fake_rtable;
 130         dst_hold(skb->dst);
 131
 132         skb->dev = nf_bridge->physindev;
 133         if (skb->protocol == htons(ETH_P_8021Q)) {
 134                 skb_push(skb, VLAN_HLEN);
 135                 skb->nh.raw -= VLAN_HLEN;
 136         }
 137         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 138                        br_handle_frame_finish, 1);
 139
 140         return 0;
 141 }
 142
 143 static void __br_dnat_complain(void)
 144 {
 145         static unsigned long last_complaint;
 146
 147         if (jiffies - last_complaint >= 5 * HZ) {
 148                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 149                        "forwarding to be enabled\n");
 150                 last_complaint = jiffies;
 151         }
 152 }
 153
 154 /* This requires some explaining. If DNAT has taken place,
 155  * we will need to fix up the destination Ethernet address,
 156  * and this is a tricky process.
 157  *
 158  * There are two cases to consider:
 159  * 1. The packet was DNAT'ed to a device in the same bridge
 160  *    port group as it was received on. We can still bridge
 161  *    the packet.
 162  * 2. The packet was DNAT'ed to a different device, either
 163  *    a non-bridged device or another bridge port group.
 164  *    The packet will need to be routed.
 165  *
 166  * The correct way of distinguishing between these two cases is to
 167  * call ip_route_input() and to look at skb->dst->dev, which is
 168  * changed to the destination device if ip_route_input() succeeds.
 169  *
 170  * Let us first consider the case that ip_route_input() succeeds:
 171  *
 172  * If skb->dst->dev equals the logical bridge device the packet
 173  * came in on, we can consider this bridging. We then call
 174  * skb->dst->output() which will make the packet enter br_nf_local_out()
 175  * not much later. In that function it is assured that the iptables
 176  * FORWARD chain is traversed for the packet.
 177  *
 178  * Otherwise, the packet is considered to be routed and we just
 179  * change the destination MAC address so that the packet will
 180  * later be passed up to the IP stack to be routed.
 181  *
 182  * Let us now consider the case that ip_route_input() fails:
 183  *
 184  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 185  * will fail, while __ip_route_output_key() will return success. The source
 186  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 187  * thinks we're handling a locally generated packet and won't care
 188  * if IP forwarding is allowed. We send a warning message to the users's
 189  * log telling her to put IP forwarding on.
 190  *
 191  * ip_route_input() will also fail if there is no route available.
 192  * In that case we just drop the packet.
 193  *
 194  * --Lennert, 20020411
 195  * --Bart, 20020416 (updated)
 196  * --Bart, 20021007 (updated) */
 197 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 198 {
 199         if (skb->pkt_type == PACKET_OTHERHOST) {
 200                 skb->pkt_type = PACKET_HOST;
 201                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 202         }
 203         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 204
 205         skb->dev = bridge_parent(skb->dev);
 206         if (!skb->dev)
 207                 kfree_skb(skb);
 208         else {
 209                 if (skb->protocol == htons(ETH_P_8021Q)) {
 210                         skb_pull(skb, VLAN_HLEN);
 211                         skb->nh.raw += VLAN_HLEN;
 212                 }
 213                 skb->dst->output(skb);
 214         }
 215         return 0;
 216 }
 217
 218 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 219 {
 220         struct net_device *dev = skb->dev;
 221         struct iphdr *iph = skb->nh.iph;
 222         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 223
 224         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 225                 skb->pkt_type = PACKET_OTHERHOST;
 226                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 227         }
 228         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 229
 230         if (dnat_took_place(skb)) {
 231                 if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev)) {
 232                         struct rtable *rt;
 233                         struct flowi fl = {
 234                                 .nl_u = {
 235                                         .ip4_u = {
 236                                                  .daddr = iph->daddr,
 237                                                  .saddr = 0,
 238                                                  .tos = RT_TOS(iph->tos) },
 239                                 },
 240                                 .proto = 0,
 241                         };
 242
 243                         if (!ip_route_output_key(&rt, &fl)) {
 244                                 /* - Bridged-and-DNAT'ed traffic doesn't
 245                                  *   require ip_forwarding.
 246                                  * - Deal with redirected traffic. */
 247                                 if (((struct dst_entry *)rt)->dev == dev ||
 248                                     rt->rt_type == RTN_LOCAL) {
 249                                         skb->dst = (struct dst_entry *)rt;
 250                                         goto bridged_dnat;
 251                                 }
 252                                 __br_dnat_complain();
 253                                 dst_release((struct dst_entry *)rt);
 254                         }
 255                         kfree_skb(skb);
 256                         return 0;
 257                 } else {
 258                         if (skb->dst->dev == dev) {
 259 bridged_dnat:
 260                                 /* Tell br_nf_local_out this is a
 261                                  * bridged frame */
 262                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 263                                 skb->dev = nf_bridge->physindev;
 264                                 if (skb->protocol ==
 265                                     htons(ETH_P_8021Q)) {
 266                                         skb_push(skb, VLAN_HLEN);
 267                                         skb->nh.raw -= VLAN_HLEN;
 268                                 }
 269                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 270                                                skb, skb->dev, NULL,
 271                                                br_nf_pre_routing_finish_bridge,
 272                                                1);
 273                                 return 0;
 274                         }
 275                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 276                         skb->pkt_type = PACKET_HOST;
 277                 }
 278         } else {
 279                 skb->dst = (struct dst_entry *)&__fake_rtable;
 280                 dst_hold(skb->dst);
 281         }
 282
 283         skb->dev = nf_bridge->physindev;
 284         if (skb->protocol == 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, skb, skb->dev, NULL,
 289                        br_handle_frame_finish, 1);
 290
 291         return 0;
 292 }
 293
 294 /* Some common code for IPv4/IPv6 */
 295 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 296 {
 297         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 298
 299         if (skb->pkt_type == PACKET_OTHERHOST) {
 300                 skb->pkt_type = PACKET_HOST;
 301                 nf_bridge->mask |= BRNF_PKT_TYPE;
 302         }
 303
 304         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 305         nf_bridge->physindev = skb->dev;
 306         skb->dev = bridge_parent(skb->dev);
 307
 308         return skb->dev;
 309 }
 310
 311 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 312 static int check_hbh_len(struct sk_buff *skb)
 313 {
 314         unsigned char *raw = (u8 *) (skb->nh.ipv6h + 1);
 315         u32 pkt_len;
 316         int off = raw - skb->nh.raw;
 317         int len = (raw[1] + 1) << 3;
 318
 319         if ((raw + len) - skb->data > skb_headlen(skb))
 320                 goto bad;
 321
 322         off += 2;
 323         len -= 2;
 324
 325         while (len > 0) {
 326                 int optlen = skb->nh.raw[off + 1] + 2;
 327
 328                 switch (skb->nh.raw[off]) {
 329                 case IPV6_TLV_PAD0:
 330                         optlen = 1;
 331                         break;
 332
 333                 case IPV6_TLV_PADN:
 334                         break;
 335
 336                 case IPV6_TLV_JUMBO:
 337                         if (skb->nh.raw[off + 1] != 4 || (off & 3) != 2)
 338                                 goto bad;
 339                         pkt_len = ntohl(*(u32 *) (skb->nh.raw + off + 2));
 340                         if (pkt_len <= IPV6_MAXPLEN ||
 341                             skb->nh.ipv6h->payload_len)
 342                                 goto bad;
 343                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 344                                 goto bad;
 345                         if (pskb_trim_rcsum(skb,
 346                                             pkt_len + sizeof(struct ipv6hdr)))
 347                                 goto bad;
 348                         break;
 349                 default:
 350                         if (optlen > len)
 351                                 goto bad;
 352                         break;
 353                 }
 354                 off += optlen;
 355                 len -= optlen;
 356         }
 357         if (len == 0)
 358                 return 0;
 359 bad:
 360         return -1;
 361
 362 }
 363
 364 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 365  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 366 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 367                                            struct sk_buff *skb,
 368                                            const struct net_device *in,
 369                                            const struct net_device *out,
 370                                            int (*okfn)(struct sk_buff *))
 371 {
 372         struct ipv6hdr *hdr;
 373         u32 pkt_len;
 374         struct nf_bridge_info *nf_bridge;
 375
 376         if (skb->len < sizeof(struct ipv6hdr))
 377                 goto inhdr_error;
 378
 379         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 380                 goto inhdr_error;
 381
 382         hdr = skb->nh.ipv6h;
 383
 384         if (hdr->version != 6)
 385                 goto inhdr_error;
 386
 387         pkt_len = ntohs(hdr->payload_len);
 388
 389         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 390                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 391                         goto inhdr_error;
 392                 if (pkt_len + sizeof(struct ipv6hdr) < skb->len) {
 393                         if (__pskb_trim(skb, pkt_len + sizeof(struct ipv6hdr)))
 394                                 goto inhdr_error;
 395                         if (skb->ip_summed == CHECKSUM_HW)
 396                                 skb->ip_summed = CHECKSUM_NONE;
 397                 }
 398         }
 399         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 400                 goto inhdr_error;
 401
 402         nf_bridge_put(skb->nf_bridge);
 403         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 404                 return NF_DROP;
 405         if (!setup_pre_routing(skb))
 406                 return NF_DROP;
 407
 408         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
 409                 br_nf_pre_routing_finish_ipv6);
 410
 411         return NF_STOLEN;
 412
 413 inhdr_error:
 414         return NF_DROP;
 415 }
 416
 417 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 418  * Replicate the checks that IPv4 does on packet reception.
 419  * Set skb->dev to the bridge device (i.e. parent of the
 420  * receiving device) to make netfilter happy, the REDIRECT
 421  * target in particular.  Save the original destination IP
 422  * address to be able to detect DNAT afterwards. */
 423 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
 424                                       const struct net_device *in,
 425                                       const struct net_device *out,
 426                                       int (*okfn)(struct sk_buff *))
 427 {
 428         struct iphdr *iph;
 429         __u32 len;
 430         struct sk_buff *skb = *pskb;
 431         struct nf_bridge_info *nf_bridge;
 432
 433         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb)) {
 434 #ifdef CONFIG_SYSCTL
 435                 if (!brnf_call_ip6tables)
 436                         return NF_ACCEPT;
 437 #endif
 438                 if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 439                         goto out;
 440
 441                 if (skb->protocol == htons(ETH_P_8021Q)) {
 442                         skb_pull_rcsum(skb, VLAN_HLEN);
 443                         skb->nh.raw += VLAN_HLEN;
 444                 }
 445                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 446         }
 447 #ifdef CONFIG_SYSCTL
 448         if (!brnf_call_iptables)
 449                 return NF_ACCEPT;
 450 #endif
 451
 452         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb))
 453                 return NF_ACCEPT;
 454
 455         if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
 456                 goto out;
 457
 458         if (skb->protocol == htons(ETH_P_8021Q)) {
 459                 skb_pull_rcsum(skb, VLAN_HLEN);
 460                 skb->nh.raw += VLAN_HLEN;
 461         }
 462
 463         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 464                 goto inhdr_error;
 465
 466         iph = skb->nh.iph;
 467         if (iph->ihl < 5 || iph->version != 4)
 468                 goto inhdr_error;
 469
 470         if (!pskb_may_pull(skb, 4 * iph->ihl))
 471                 goto inhdr_error;
 472
 473         iph = skb->nh.iph;
 474         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 475                 goto inhdr_error;
 476
 477         len = ntohs(iph->tot_len);
 478         if (skb->len < len || len < 4 * iph->ihl)
 479                 goto inhdr_error;
 480
 481         if (skb->len > len) {
 482                 __pskb_trim(skb, len);
 483                 if (skb->ip_summed == CHECKSUM_HW)
 484                         skb->ip_summed = CHECKSUM_NONE;
 485         }
 486
 487         nf_bridge_put(skb->nf_bridge);
 488         if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
 489                 return NF_DROP;
 490         if (!setup_pre_routing(skb))
 491                 return NF_DROP;
 492         store_orig_dstaddr(skb);
 493
 494         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
 495                 br_nf_pre_routing_finish);
 496
 497         return NF_STOLEN;
 498
 499 inhdr_error:
 500 //      IP_INC_STATS_BH(IpInHdrErrors);
 501 out:
 502         return NF_DROP;
 503 }
 504
 505
 506 /* PF_BRIDGE/LOCAL_IN ************************************************/
 507 /* The packet is locally destined, which requires a real
 508  * dst_entry, so detach the fake one.  On the way up, the
 509  * packet would pass through PRE_ROUTING again (which already
 510  * took place when the packet entered the bridge), but we
 511  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 512  * prevent this from happening. */
 513 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
 514                                    const struct net_device *in,
 515                                    const struct net_device *out,
 516                                    int (*okfn)(struct sk_buff *))
 517 {
 518         struct sk_buff *skb = *pskb;
 519
 520         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 521                 dst_release(skb->dst);
 522                 skb->dst = NULL;
 523         }
 524
 525         return NF_ACCEPT;
 526 }
 527
 528 /* PF_BRIDGE/FORWARD *************************************************/
 529 static int br_nf_forward_finish(struct sk_buff *skb)
 530 {
 531         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 532         struct net_device *in;
 533
 534         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 535                 in = nf_bridge->physindev;
 536                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 537                         skb->pkt_type = PACKET_OTHERHOST;
 538                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 539                 }
 540         } else {
 541                 in = *((struct net_device **)(skb->cb));
 542         }
 543         if (skb->protocol == htons(ETH_P_8021Q)) {
 544                 skb_push(skb, VLAN_HLEN);
 545                 skb->nh.raw -= VLAN_HLEN;
 546         }
 547         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 548                        skb->dev, br_forward_finish, 1);
 549         return 0;
 550 }
 551
 552 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 553  * netfilter with indev and outdev set to the bridge device,
 554  * but we are still able to filter on the 'real' indev/outdev
 555  * because of the physdev module. For ARP, indev and outdev are the
 556  * bridge ports. */
 557 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
 558                                      const struct net_device *in,
 559                                      const struct net_device *out,
 560                                      int (*okfn)(struct sk_buff *))
 561 {
 562         struct sk_buff *skb = *pskb;
 563         struct nf_bridge_info *nf_bridge;
 564         struct net_device *parent;
 565         int pf;
 566
 567         if (!skb->nf_bridge)
 568                 return NF_ACCEPT;
 569
 570         parent = bridge_parent(out);
 571         if (!parent)
 572                 return NF_DROP;
 573
 574         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 575                 pf = PF_INET;
 576         else
 577                 pf = PF_INET6;
 578
 579         if (skb->protocol == htons(ETH_P_8021Q)) {
 580                 skb_pull(*pskb, VLAN_HLEN);
 581                 (*pskb)->nh.raw += VLAN_HLEN;
 582         }
 583
 584         nf_bridge = skb->nf_bridge;
 585         if (skb->pkt_type == PACKET_OTHERHOST) {
 586                 skb->pkt_type = PACKET_HOST;
 587                 nf_bridge->mask |= BRNF_PKT_TYPE;
 588         }
 589
 590         /* The physdev module checks on this */
 591         nf_bridge->mask |= BRNF_BRIDGED;
 592         nf_bridge->physoutdev = skb->dev;
 593
 594         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
 595                 br_nf_forward_finish);
 596
 597         return NF_STOLEN;
 598 }
 599
 600 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
 601                                       const struct net_device *in,
 602                                       const struct net_device *out,
 603                                       int (*okfn)(struct sk_buff *))
 604 {
 605         struct sk_buff *skb = *pskb;
 606         struct net_device **d = (struct net_device **)(skb->cb);
 607
 608 #ifdef CONFIG_SYSCTL
 609         if (!brnf_call_arptables)
 610                 return NF_ACCEPT;
 611 #endif
 612
 613         if (skb->protocol != htons(ETH_P_ARP)) {
 614                 if (!IS_VLAN_ARP(skb))
 615                         return NF_ACCEPT;
 616                 skb_pull(*pskb, VLAN_HLEN);
 617                 (*pskb)->nh.raw += VLAN_HLEN;
 618         }
 619
 620         if (skb->nh.arph->ar_pln != 4) {
 621                 if (IS_VLAN_ARP(skb)) {
 622                         skb_push(*pskb, VLAN_HLEN);
 623                         (*pskb)->nh.raw -= VLAN_HLEN;
 624                 }
 625                 return NF_ACCEPT;
 626         }
 627         *d = (struct net_device *)in;
 628         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 629                 (struct net_device *)out, br_nf_forward_finish);
 630
 631         return NF_STOLEN;
 632 }
 633
 634 /* PF_BRIDGE/LOCAL_OUT ***********************************************/
 635 static int br_nf_local_out_finish(struct sk_buff *skb)
 636 {
 637         if (skb->protocol == htons(ETH_P_8021Q)) {
 638                 skb_push(skb, VLAN_HLEN);
 639                 skb->nh.raw -= VLAN_HLEN;
 640         }
 641
 642         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 643                        br_forward_finish, NF_BR_PRI_FIRST + 1);
 644
 645         return 0;
 646 }
 647
 648 /* This function sees both locally originated IP packets and forwarded
 649  * IP packets (in both cases the destination device is a bridge
 650  * device). It also sees bridged-and-DNAT'ed packets.
 651  * To be able to filter on the physical bridge devices (with the physdev
 652  * module), we steal packets destined to a bridge device away from the
 653  * PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
 654  * when we have determined the real output device. This is done in here.
 655  *
 656  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 657  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 658  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 659  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 660  * will be executed.
 661  * Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
 662  * this packet before, and so the packet was locally originated. We fake
 663  * the PF_INET/LOCAL_OUT hook.
 664  * Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
 665  * so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
 666  * even routed packets that didn't arrive on a bridge interface have their
 667  * nf_bridge->physindev set. */
 668 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
 669                                     const struct net_device *in,
 670                                     const struct net_device *out,
 671                                     int (*okfn)(struct sk_buff *))
 672 {
 673         struct net_device *realindev, *realoutdev;
 674         struct sk_buff *skb = *pskb;
 675         struct nf_bridge_info *nf_bridge;
 676         int pf;
 677
 678         if (!skb->nf_bridge)
 679                 return NF_ACCEPT;
 680
 681         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 682                 pf = PF_INET;
 683         else
 684                 pf = PF_INET6;
 685
 686 #ifdef CONFIG_NETFILTER_DEBUG
 687         /* Sometimes we get packets with NULL ->dst here (for example,
 688          * running a dhcp client daemon triggers this). This should now
 689          * be fixed, but let's keep the check around. */
 690         if (skb->dst == NULL) {
 691                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 692                 return NF_ACCEPT;
 693         }
 694 #endif
 695
 696         nf_bridge = skb->nf_bridge;
 697         nf_bridge->physoutdev = skb->dev;
 698         realindev = nf_bridge->physindev;
 699
 700         /* Bridged, take PF_BRIDGE/FORWARD.
 701          * (see big note in front of br_nf_pre_routing_finish) */
 702         if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
 703                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 704                         skb->pkt_type = PACKET_OTHERHOST;
 705                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 706                 }
 707                 if (skb->protocol == htons(ETH_P_8021Q)) {
 708                         skb_push(skb, VLAN_HLEN);
 709                         skb->nh.raw -= VLAN_HLEN;
 710                 }
 711
 712                 NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
 713                         skb->dev, br_forward_finish);
 714                 goto out;
 715         }
 716         realoutdev = bridge_parent(skb->dev);
 717         if (!realoutdev)
 718                 return NF_DROP;
 719
 720 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 721         /* iptables should match -o br0.x */
 722         if (nf_bridge->netoutdev)
 723                 realoutdev = nf_bridge->netoutdev;
 724 #endif
 725         if (skb->protocol == htons(ETH_P_8021Q)) {
 726                 skb_pull(skb, VLAN_HLEN);
 727                 (*pskb)->nh.raw += VLAN_HLEN;
 728         }
 729         /* IP forwarded traffic has a physindev, locally
 730          * generated traffic hasn't. */
 731         if (realindev != NULL) {
 732                 if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT)) {
 733                         struct net_device *parent = bridge_parent(realindev);
 734                         if (parent)
 735                                 realindev = parent;
 736                 }
 737
 738                 NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
 739                                realoutdev, br_nf_local_out_finish,
 740                                NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
 741         } else {
 742                 NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
 743                                realoutdev, br_nf_local_out_finish,
 744                                NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
 745         }
 746
 747 out:
 748         return NF_STOLEN;
 749 }
 750
 751
 752 /* PF_BRIDGE/POST_ROUTING ********************************************/
 753 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
 754                                        const struct net_device *in,
 755                                        const struct net_device *out,
 756                                        int (*okfn)(struct sk_buff *))
 757 {
 758         struct sk_buff *skb = *pskb;
 759         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
 760         struct net_device *realoutdev = bridge_parent(skb->dev);
 761         int pf;
 762
 763 #ifdef CONFIG_NETFILTER_DEBUG
 764         /* Be very paranoid. This probably won't happen anymore, but let's
 765          * keep the check just to be sure... */
 766         if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
 767                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 768                        "bad mac.raw pointer.");
 769                 goto print_error;
 770         }
 771 #endif
 772
 773         if (!nf_bridge)
 774                 return NF_ACCEPT;
 775
 776         if (!realoutdev)
 777                 return NF_DROP;
 778
 779         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
 780                 pf = PF_INET;
 781         else
 782                 pf = PF_INET6;
 783
 784 #ifdef CONFIG_NETFILTER_DEBUG
 785         if (skb->dst == NULL) {
 786                 printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
 787                 goto print_error;
 788         }
 789 #endif
 790
 791         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 792          * about the value of skb->pkt_type. */
 793         if (skb->pkt_type == PACKET_OTHERHOST) {
 794                 skb->pkt_type = PACKET_HOST;
 795                 nf_bridge->mask |= BRNF_PKT_TYPE;
 796         }
 797
 798         if (skb->protocol == htons(ETH_P_8021Q)) {
 799                 skb_pull(skb, VLAN_HLEN);
 800                 skb->nh.raw += VLAN_HLEN;
 801         }
 802
 803         nf_bridge_save_header(skb);
 804
 805 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 806         if (nf_bridge->netoutdev)
 807                 realoutdev = nf_bridge->netoutdev;
 808 #endif
 809         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
 810                 br_dev_queue_push_xmit);
 811
 812         return NF_STOLEN;
 813
 814 #ifdef CONFIG_NETFILTER_DEBUG
 815 print_error:
 816         if (skb->dev != NULL) {
 817                 printk("[%s]", skb->dev->name);
 818                 if (realoutdev)
 819                         printk("[%s]", realoutdev->name);
 820         }
 821         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
 822                skb->data);
 823         return NF_ACCEPT;
 824 #endif
 825 }
 826
 827 /* IP/SABOTAGE *****************************************************/
 828 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 829  * for the second time. */
 830 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
 831                                    const struct net_device *in,
 832                                    const struct net_device *out,
 833                                    int (*okfn)(struct sk_buff *))
 834 {
 835         if ((*pskb)->nf_bridge &&
 836             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 837                 return NF_STOP;
 838         }
 839
 840         return NF_ACCEPT;
 841 }
 842
 843 /* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
 844  * and PF_INET(6)/POST_ROUTING until we have done the forwarding
 845  * decision in the bridge code and have determined nf_bridge->physoutdev. */
 846 static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
 847                                     const struct net_device *in,
 848                                     const struct net_device *out,
 849                                     int (*okfn)(struct sk_buff *))
 850 {
 851         struct sk_buff *skb = *pskb;
 852
 853         if ((out->hard_start_xmit == br_dev_xmit &&
 854              okfn != br_nf_forward_finish &&
 855              okfn != br_nf_local_out_finish && okfn != br_dev_queue_push_xmit)
 856 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 857             || ((out->priv_flags & IFF_802_1Q_VLAN) &&
 858                 VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
 859 #endif
 860             ) {
 861                 struct nf_bridge_info *nf_bridge;
 862
 863                 if (!skb->nf_bridge) {
 864 #ifdef CONFIG_SYSCTL
 865                         /* This code is executed while in the IP(v6) stack,
 866                            the version should be 4 or 6. We can't use
 867                            skb->protocol because that isn't set on
 868                            PF_INET(6)/LOCAL_OUT. */
 869                         struct iphdr *ip = skb->nh.iph;
 870
 871                         if (ip->version == 4 && !brnf_call_iptables)
 872                                 return NF_ACCEPT;
 873                         else if (ip->version == 6 && !brnf_call_ip6tables)
 874                                 return NF_ACCEPT;
 875 #endif
 876                         if (hook == NF_IP_POST_ROUTING)
 877                                 return NF_ACCEPT;
 878                         if (!nf_bridge_alloc(skb))
 879                                 return NF_DROP;
 880                 }
 881
 882                 nf_bridge = skb->nf_bridge;
 883
 884                 /* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
 885                  * will need the indev then. For a brouter, the real indev
 886                  * can be a bridge port, so we make sure br_nf_local_out()
 887                  * doesn't use the bridge parent of the indev by using
 888                  * the BRNF_DONT_TAKE_PARENT mask. */
 889                 if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
 890                         nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
 891                         nf_bridge->physindev = (struct net_device *)in;
 892                 }
 893 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 894                 /* the iptables outdev is br0.x, not br0 */
 895                 if (out->priv_flags & IFF_802_1Q_VLAN)
 896                         nf_bridge->netoutdev = (struct net_device *)out;
 897 #endif
 898                 return NF_STOP;
 899         }
 900
 901         return NF_ACCEPT;
 902 }
 903
 904 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 905  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 906  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 907  * ip_refrag() can return NF_STOLEN. */
 908 static struct nf_hook_ops br_nf_ops[] = {
 909         { .hook = br_nf_pre_routing,
 910           .owner = THIS_MODULE,
 911           .pf = PF_BRIDGE,
 912           .hooknum = NF_BR_PRE_ROUTING,
 913           .priority = NF_BR_PRI_BRNF, },
 914         { .hook = br_nf_local_in,
 915           .owner = THIS_MODULE,
 916           .pf = PF_BRIDGE,
 917           .hooknum = NF_BR_LOCAL_IN,
 918           .priority = NF_BR_PRI_BRNF, },
 919         { .hook = br_nf_forward_ip,
 920           .owner = THIS_MODULE,
 921           .pf = PF_BRIDGE,
 922           .hooknum = NF_BR_FORWARD,
 923           .priority = NF_BR_PRI_BRNF - 1, },
 924         { .hook = br_nf_forward_arp,
 925           .owner = THIS_MODULE,
 926           .pf = PF_BRIDGE,
 927           .hooknum = NF_BR_FORWARD,
 928           .priority = NF_BR_PRI_BRNF, },
 929         { .hook = br_nf_local_out,
 930           .owner = THIS_MODULE,
 931           .pf = PF_BRIDGE,
 932           .hooknum = NF_BR_LOCAL_OUT,
 933           .priority = NF_BR_PRI_FIRST, },
 934         { .hook = br_nf_post_routing,
 935           .owner = THIS_MODULE,
 936           .pf = PF_BRIDGE,
 937           .hooknum = NF_BR_POST_ROUTING,
 938           .priority = NF_BR_PRI_LAST, },
 939         { .hook = ip_sabotage_in,
 940           .owner = THIS_MODULE,
 941           .pf = PF_INET,
 942           .hooknum = NF_IP_PRE_ROUTING,
 943           .priority = NF_IP_PRI_FIRST, },
 944         { .hook = ip_sabotage_in,
 945           .owner = THIS_MODULE,
 946           .pf = PF_INET6,
 947           .hooknum = NF_IP6_PRE_ROUTING,
 948           .priority = NF_IP6_PRI_FIRST, },
 949         { .hook = ip_sabotage_out,
 950           .owner = THIS_MODULE,
 951           .pf = PF_INET,
 952           .hooknum = NF_IP_FORWARD,
 953           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
 954         { .hook = ip_sabotage_out,
 955           .owner = THIS_MODULE,
 956           .pf = PF_INET6,
 957           .hooknum = NF_IP6_FORWARD,
 958           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
 959         { .hook = ip_sabotage_out,
 960           .owner = THIS_MODULE,
 961           .pf = PF_INET,
 962           .hooknum = NF_IP_LOCAL_OUT,
 963           .priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 964         { .hook = ip_sabotage_out,
 965           .owner = THIS_MODULE,
 966           .pf = PF_INET6,
 967           .hooknum = NF_IP6_LOCAL_OUT,
 968           .priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
 969         { .hook = ip_sabotage_out,
 970           .owner = THIS_MODULE,
 971           .pf = PF_INET,
 972           .hooknum = NF_IP_POST_ROUTING,
 973           .priority = NF_IP_PRI_FIRST, },
 974         { .hook = ip_sabotage_out,
 975           .owner = THIS_MODULE,
 976           .pf = PF_INET6,
 977           .hooknum = NF_IP6_POST_ROUTING,
 978           .priority = NF_IP6_PRI_FIRST, },
 979 };
 980
 981 #ifdef CONFIG_SYSCTL
 982 static
 983 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
 984                             void __user * buffer, size_t * lenp, loff_t * ppos)
 985 {
 986         int ret;
 987
 988         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 989
 990         if (write && *(int *)(ctl->data))
 991                 *(int *)(ctl->data) = 1;
 992         return ret;
 993 }
 994
 995 static ctl_table brnf_table[] = {
 996         {
 997                 .ctl_name       = NET_BRIDGE_NF_CALL_ARPTABLES,
 998                 .procname       = "bridge-nf-call-arptables",
 999                 .data           = &brnf_call_arptables,
1000                 .maxlen         = sizeof(int),
1001                 .mode           = 0644,
1002                 .proc_handler   = &brnf_sysctl_call_tables,
1003         },
1004         {
1005                 .ctl_name       = NET_BRIDGE_NF_CALL_IPTABLES,
1006                 .procname       = "bridge-nf-call-iptables",
1007                 .data           = &brnf_call_iptables,
1008                 .maxlen         = sizeof(int),
1009                 .mode           = 0644,
1010                 .proc_handler   = &brnf_sysctl_call_tables,
1011         },
1012         {
1013                 .ctl_name       = NET_BRIDGE_NF_CALL_IP6TABLES,
1014                 .procname       = "bridge-nf-call-ip6tables",
1015                 .data           = &brnf_call_ip6tables,
1016                 .maxlen         = sizeof(int),
1017                 .mode           = 0644,
1018                 .proc_handler   = &brnf_sysctl_call_tables,
1019         },
1020         {
1021                 .ctl_name       = NET_BRIDGE_NF_FILTER_VLAN_TAGGED,
1022                 .procname       = "bridge-nf-filter-vlan-tagged",
1023                 .data           = &brnf_filter_vlan_tagged,
1024                 .maxlen         = sizeof(int),
1025                 .mode           = 0644,
1026                 .proc_handler   = &brnf_sysctl_call_tables,
1027         },
1028         { .ctl_name = 0 }
1029 };
1030
1031 static ctl_table brnf_bridge_table[] = {
1032         {
1033                 .ctl_name       = NET_BRIDGE,
1034                 .procname       = "bridge",
1035                 .mode           = 0555,
1036                 .child          = brnf_table,
1037         },
1038         { .ctl_name = 0 }
1039 };
1040
1041 static ctl_table brnf_net_table[] = {
1042         {
1043                 .ctl_name       = CTL_NET,
1044                 .procname       = "net",
1045                 .mode           = 0555,
1046                 .child          = brnf_bridge_table,
1047         },
1048         { .ctl_name = 0 }
1049 };
1050 #endif
1051
1052 int br_netfilter_init(void)
1053 {
1054         int i;
1055
1056         for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++) {
1057                 int ret;
1058
1059                 if ((ret = nf_register_hook(&br_nf_ops[i])) >= 0)
1060                         continue;
1061
1062                 while (i--)
1063                         nf_unregister_hook(&br_nf_ops[i]);
1064
1065                 return ret;
1066         }
1067
1068 #ifdef CONFIG_SYSCTL
1069         brnf_sysctl_header = register_sysctl_table(brnf_net_table, 0);
1070         if (brnf_sysctl_header == NULL) {
1071                 printk(KERN_WARNING
1072                        "br_netfilter: can't register to sysctl.\n");
1073                 for (i = 0; i < ARRAY_SIZE(br_nf_ops); i++)
1074                         nf_unregister_hook(&br_nf_ops[i]);
1075                 return -EFAULT;
1076         }
1077 #endif
1078
1079         printk(KERN_NOTICE "Bridge firewalling registered\n");
1080
1081         return 0;
1082 }
1083
1084 void br_netfilter_fini(void)
1085 {
1086         int i;
1087
1088         for (i = ARRAY_SIZE(br_nf_ops) - 1; i >= 0; i--)
1089                 nf_unregister_hook(&br_nf_ops[i]);
1090 #ifdef CONFIG_SYSCTL
1091         unregister_sysctl_table(brnf_sysctl_header);
1092 #endif
1093 }