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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/if_pppox.h>
  33 #include <linux/ppp_defs.h>
  34 #include <linux/netfilter_bridge.h>
  35 #include <linux/netfilter_ipv4.h>
  36 #include <linux/netfilter_ipv6.h>
  37 #include <linux/netfilter_arp.h>
  38 #include <linux/in_route.h>
  39 #include <linux/inetdevice.h>
  40
  41 #include <net/ip.h>
  42 #include <net/ipv6.h>
  43 #include <net/route.h>
  44
  45 #include <asm/uaccess.h>
  46 #include "br_private.h"
  47 #ifdef CONFIG_SYSCTL
  48 #include <linux/sysctl.h>
  49 #endif
  50
  51 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  52                                  (skb->nf_bridge->data))->daddr.ipv4)
  53 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  54 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  55
  56 #ifdef CONFIG_SYSCTL
  57 static struct ctl_table_header *brnf_sysctl_header;
  58 static int brnf_call_iptables __read_mostly = 1;
  59 static int brnf_call_ip6tables __read_mostly = 1;
  60 static int brnf_call_arptables __read_mostly = 1;
  61 static int brnf_filter_vlan_tagged __read_mostly = 1;
  62 static int brnf_filter_pppoe_tagged __read_mostly = 1;
  63 #else
  64 #define brnf_filter_vlan_tagged 1
  65 #define brnf_filter_pppoe_tagged 1
  66 #endif
  67
  68 static inline __be16 vlan_proto(const struct sk_buff *skb)
  69 {
  70         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  71 }
  72
  73 #define IS_VLAN_IP(skb) \
  74         (skb->protocol == htons(ETH_P_8021Q) && \
  75          vlan_proto(skb) == htons(ETH_P_IP) &&  \
  76          brnf_filter_vlan_tagged)
  77
  78 #define IS_VLAN_IPV6(skb) \
  79         (skb->protocol == htons(ETH_P_8021Q) && \
  80          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
  81          brnf_filter_vlan_tagged)
  82
  83 #define IS_VLAN_ARP(skb) \
  84         (skb->protocol == htons(ETH_P_8021Q) && \
  85          vlan_proto(skb) == htons(ETH_P_ARP) && \
  86          brnf_filter_vlan_tagged)
  87
  88 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  89 {
  90         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  91                             sizeof(struct pppoe_hdr)));
  92 }
  93
  94 #define IS_PPPOE_IP(skb) \
  95         (skb->protocol == htons(ETH_P_PPP_SES) && \
  96          pppoe_proto(skb) == htons(PPP_IP) && \
  97          brnf_filter_pppoe_tagged)
  98
  99 #define IS_PPPOE_IPV6(skb) \
 100         (skb->protocol == htons(ETH_P_PPP_SES) && \
 101          pppoe_proto(skb) == htons(PPP_IPV6) && \
 102          brnf_filter_pppoe_tagged)
 103
 104 /* We need these fake structures to make netfilter happy --
 105  * lots of places assume that skb->dst != NULL, which isn't
 106  * all that unreasonable.
 107  *
 108  * Currently, we fill in the PMTU entry because netfilter
 109  * refragmentation needs it, and the rt_flags entry because
 110  * ipt_REJECT needs it.  Future netfilter modules might
 111  * require us to fill additional fields. */
 112 static struct net_device __fake_net_device = {
 113         .hard_header_len        = ETH_HLEN
 114 };
 115
 116 static struct rtable __fake_rtable = {
 117         .u = {
 118                 .dst = {
 119                         .__refcnt               = ATOMIC_INIT(1),
 120                         .dev                    = &__fake_net_device,
 121                         .path                   = &__fake_rtable.u.dst,
 122                         .metrics                = {[RTAX_MTU - 1] = 1500},
 123                         .flags                  = DST_NOXFRM,
 124                 }
 125         },
 126         .rt_flags       = 0,
 127 };
 128
 129 static inline struct net_device *bridge_parent(const struct net_device *dev)
 130 {
 131         struct net_bridge_port *port = rcu_dereference(dev->br_port);
 132
 133         return port ? port->br->dev : NULL;
 134 }
 135
 136 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 137 {
 138         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 139         if (likely(skb->nf_bridge))
 140                 atomic_set(&(skb->nf_bridge->use), 1);
 141
 142         return skb->nf_bridge;
 143 }
 144
 145 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 146 {
 147         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 148
 149         if (atomic_read(&nf_bridge->use) > 1) {
 150                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 151
 152                 if (tmp) {
 153                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 154                         atomic_set(&tmp->use, 1);
 155                         nf_bridge_put(nf_bridge);
 156                 }
 157                 nf_bridge = tmp;
 158         }
 159         return nf_bridge;
 160 }
 161
 162 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 163 {
 164         unsigned int len = nf_bridge_encap_header_len(skb);
 165
 166         skb_push(skb, len);
 167         skb->network_header -= len;
 168 }
 169
 170 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 171 {
 172         unsigned int len = nf_bridge_encap_header_len(skb);
 173
 174         skb_pull(skb, len);
 175         skb->network_header += len;
 176 }
 177
 178 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 179 {
 180         unsigned int len = nf_bridge_encap_header_len(skb);
 181
 182         skb_pull_rcsum(skb, len);
 183         skb->network_header += len;
 184 }
 185
 186 static inline void nf_bridge_save_header(struct sk_buff *skb)
 187 {
 188         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 189
 190         skb_copy_from_linear_data_offset(skb, -header_size,
 191                                          skb->nf_bridge->data, header_size);
 192 }
 193
 194 /*
 195  * When forwarding bridge frames, we save a copy of the original
 196  * header before processing.
 197  */
 198 int nf_bridge_copy_header(struct sk_buff *skb)
 199 {
 200         int err;
 201         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 202
 203         err = skb_cow_head(skb, header_size);
 204         if (err)
 205                 return err;
 206
 207         skb_copy_to_linear_data_offset(skb, -header_size,
 208                                        skb->nf_bridge->data, header_size);
 209         __skb_push(skb, nf_bridge_encap_header_len(skb));
 210         return 0;
 211 }
 212
 213 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 214 /* Undo the changes made for ip6tables PREROUTING and continue the
 215  * bridge PRE_ROUTING hook. */
 216 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 217 {
 218         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 219
 220         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 221                 skb->pkt_type = PACKET_OTHERHOST;
 222                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 223         }
 224         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 225
 226         skb->dst = (struct dst_entry *)&__fake_rtable;
 227         dst_hold(skb->dst);
 228
 229         skb->dev = nf_bridge->physindev;
 230         nf_bridge_push_encap_header(skb);
 231         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 232                        br_handle_frame_finish, 1);
 233
 234         return 0;
 235 }
 236
 237 static void __br_dnat_complain(void)
 238 {
 239         static unsigned long last_complaint;
 240
 241         if (jiffies - last_complaint >= 5 * HZ) {
 242                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
 243                        "forwarding to be enabled\n");
 244                 last_complaint = jiffies;
 245         }
 246 }
 247
 248 /* This requires some explaining. If DNAT has taken place,
 249  * we will need to fix up the destination Ethernet address,
 250  * and this is a tricky process.
 251  *
 252  * There are two cases to consider:
 253  * 1. The packet was DNAT'ed to a device in the same bridge
 254  *    port group as it was received on. We can still bridge
 255  *    the packet.
 256  * 2. The packet was DNAT'ed to a different device, either
 257  *    a non-bridged device or another bridge port group.
 258  *    The packet will need to be routed.
 259  *
 260  * The correct way of distinguishing between these two cases is to
 261  * call ip_route_input() and to look at skb->dst->dev, which is
 262  * changed to the destination device if ip_route_input() succeeds.
 263  *
 264  * Let us first consider the case that ip_route_input() succeeds:
 265  *
 266  * If skb->dst->dev equals the logical bridge device the packet
 267  * came in on, we can consider this bridging. The packet is passed
 268  * through the neighbour output function to build a new destination
 269  * MAC address, which will make the packet enter br_nf_local_out()
 270  * not much later. In that function it is assured that the iptables
 271  * FORWARD chain is traversed for the packet.
 272  *
 273  * Otherwise, the packet is considered to be routed and we just
 274  * change the destination MAC address so that the packet will
 275  * later be passed up to the IP stack to be routed. For a redirected
 276  * packet, ip_route_input() will give back the localhost as output device,
 277  * which differs from the bridge device.
 278  *
 279  * Let us now consider the case that ip_route_input() fails:
 280  *
 281  * This can be because the destination address is martian, in which case
 282  * the packet will be dropped.
 283  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
 284  * will fail, while __ip_route_output_key() will return success. The source
 285  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
 286  * thinks we're handling a locally generated packet and won't care
 287  * if IP forwarding is allowed. We send a warning message to the users's
 288  * log telling her to put IP forwarding on.
 289  *
 290  * ip_route_input() will also fail if there is no route available.
 291  * In that case we just drop the packet.
 292  *
 293  * --Lennert, 20020411
 294  * --Bart, 20020416 (updated)
 295  * --Bart, 20021007 (updated)
 296  * --Bart, 20062711 (updated) */
 297 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 298 {
 299         if (skb->pkt_type == PACKET_OTHERHOST) {
 300                 skb->pkt_type = PACKET_HOST;
 301                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
 302         }
 303         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 304
 305         skb->dev = bridge_parent(skb->dev);
 306         if (skb->dev) {
 307                 struct dst_entry *dst = skb->dst;
 308
 309                 nf_bridge_pull_encap_header(skb);
 310
 311                 if (dst->hh)
 312                         return neigh_hh_output(dst->hh, skb);
 313                 else if (dst->neighbour)
 314                         return dst->neighbour->output(skb);
 315         }
 316         kfree_skb(skb);
 317         return 0;
 318 }
 319
 320 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 321 {
 322         struct net_device *dev = skb->dev;
 323         struct iphdr *iph = ip_hdr(skb);
 324         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 325         int err;
 326
 327         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 328                 skb->pkt_type = PACKET_OTHERHOST;
 329                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 330         }
 331         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 332         if (dnat_took_place(skb)) {
 333                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 334                         struct rtable *rt;
 335                         struct flowi fl = {
 336                                 .nl_u = {
 337                                         .ip4_u = {
 338                                                  .daddr = iph->daddr,
 339                                                  .saddr = 0,
 340                                                  .tos = RT_TOS(iph->tos) },
 341                                 },
 342                                 .proto = 0,
 343                         };
 344                         struct in_device *in_dev = in_dev_get(dev);
 345
 346                         /* If err equals -EHOSTUNREACH the error is due to a
 347                          * martian destination or due to the fact that
 348                          * forwarding is disabled. For most martian packets,
 349                          * ip_route_output_key() will fail. It won't fail for 2 types of
 350                          * martian destinations: loopback destinations and destination
 351                          * 0.0.0.0. In both cases the packet will be dropped because the
 352                          * destination is the loopback device and not the bridge. */
 353                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 354                                 goto free_skb;
 355
 356                         if (!ip_route_output_key(&rt, &fl)) {
 357                                 /* - Bridged-and-DNAT'ed traffic doesn't
 358                                  *   require ip_forwarding. */
 359                                 if (((struct dst_entry *)rt)->dev == dev) {
 360                                         skb->dst = (struct dst_entry *)rt;
 361                                         goto bridged_dnat;
 362                                 }
 363                                 /* we are sure that forwarding is disabled, so printing
 364                                  * this message is no problem. Note that the packet could
 365                                  * still have a martian destination address, in which case
 366                                  * the packet could be dropped even if forwarding were enabled */
 367                                 __br_dnat_complain();
 368                                 dst_release((struct dst_entry *)rt);
 369                         }
 370 free_skb:
 371                         kfree_skb(skb);
 372                         return 0;
 373                 } else {
 374                         if (skb->dst->dev == dev) {
 375 bridged_dnat:
 376                                 /* Tell br_nf_local_out this is a
 377                                  * bridged frame */
 378                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 379                                 skb->dev = nf_bridge->physindev;
 380                                 nf_bridge_push_encap_header(skb);
 381                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
 382                                                skb, skb->dev, NULL,
 383                                                br_nf_pre_routing_finish_bridge,
 384                                                1);
 385                                 return 0;
 386                         }
 387                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 388                         skb->pkt_type = PACKET_HOST;
 389                 }
 390         } else {
 391                 skb->dst = (struct dst_entry *)&__fake_rtable;
 392                 dst_hold(skb->dst);
 393         }
 394
 395         skb->dev = nf_bridge->physindev;
 396         nf_bridge_push_encap_header(skb);
 397         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 398                        br_handle_frame_finish, 1);
 399
 400         return 0;
 401 }
 402
 403 /* Some common code for IPv4/IPv6 */
 404 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 405 {
 406         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 407
 408         if (skb->pkt_type == PACKET_OTHERHOST) {
 409                 skb->pkt_type = PACKET_HOST;
 410                 nf_bridge->mask |= BRNF_PKT_TYPE;
 411         }
 412
 413         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 414         nf_bridge->physindev = skb->dev;
 415         skb->dev = bridge_parent(skb->dev);
 416
 417         return skb->dev;
 418 }
 419
 420 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 421 static int check_hbh_len(struct sk_buff *skb)
 422 {
 423         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 424         u32 pkt_len;
 425         const unsigned char *nh = skb_network_header(skb);
 426         int off = raw - nh;
 427         int len = (raw[1] + 1) << 3;
 428
 429         if ((raw + len) - skb->data > skb_headlen(skb))
 430                 goto bad;
 431
 432         off += 2;
 433         len -= 2;
 434
 435         while (len > 0) {
 436                 int optlen = nh[off + 1] + 2;
 437
 438                 switch (nh[off]) {
 439                 case IPV6_TLV_PAD0:
 440                         optlen = 1;
 441                         break;
 442
 443                 case IPV6_TLV_PADN:
 444                         break;
 445
 446                 case IPV6_TLV_JUMBO:
 447                         if (nh[off + 1] != 4 || (off & 3) != 2)
 448                                 goto bad;
 449                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 450                         if (pkt_len <= IPV6_MAXPLEN ||
 451                             ipv6_hdr(skb)->payload_len)
 452                                 goto bad;
 453                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 454                                 goto bad;
 455                         if (pskb_trim_rcsum(skb,
 456                                             pkt_len + sizeof(struct ipv6hdr)))
 457                                 goto bad;
 458                         nh = skb_network_header(skb);
 459                         break;
 460                 default:
 461                         if (optlen > len)
 462                                 goto bad;
 463                         break;
 464                 }
 465                 off += optlen;
 466                 len -= optlen;
 467         }
 468         if (len == 0)
 469                 return 0;
 470 bad:
 471         return -1;
 472
 473 }
 474
 475 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 476  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 477 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 478                                            struct sk_buff *skb,
 479                                            const struct net_device *in,
 480                                            const struct net_device *out,
 481                                            int (*okfn)(struct sk_buff *))
 482 {
 483         struct ipv6hdr *hdr;
 484         u32 pkt_len;
 485
 486         if (skb->len < sizeof(struct ipv6hdr))
 487                 goto inhdr_error;
 488
 489         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 490                 goto inhdr_error;
 491
 492         hdr = ipv6_hdr(skb);
 493
 494         if (hdr->version != 6)
 495                 goto inhdr_error;
 496
 497         pkt_len = ntohs(hdr->payload_len);
 498
 499         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 500                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 501                         goto inhdr_error;
 502                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 503                         goto inhdr_error;
 504         }
 505         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 506                 goto inhdr_error;
 507
 508         nf_bridge_put(skb->nf_bridge);
 509         if (!nf_bridge_alloc(skb))
 510                 return NF_DROP;
 511         if (!setup_pre_routing(skb))
 512                 return NF_DROP;
 513
 514         NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 515                 br_nf_pre_routing_finish_ipv6);
 516
 517         return NF_STOLEN;
 518
 519 inhdr_error:
 520         return NF_DROP;
 521 }
 522
 523 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 524  * Replicate the checks that IPv4 does on packet reception.
 525  * Set skb->dev to the bridge device (i.e. parent of the
 526  * receiving device) to make netfilter happy, the REDIRECT
 527  * target in particular.  Save the original destination IP
 528  * address to be able to detect DNAT afterwards. */
 529 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 530                                       const struct net_device *in,
 531                                       const struct net_device *out,
 532                                       int (*okfn)(struct sk_buff *))
 533 {
 534         struct iphdr *iph;
 535         __u32 len = nf_bridge_encap_header_len(skb);
 536
 537         if (unlikely(!pskb_may_pull(skb, len)))
 538                 goto out;
 539
 540         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 541             IS_PPPOE_IPV6(skb)) {
 542 #ifdef CONFIG_SYSCTL
 543                 if (!brnf_call_ip6tables)
 544                         return NF_ACCEPT;
 545 #endif
 546                 nf_bridge_pull_encap_header_rcsum(skb);
 547                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 548         }
 549 #ifdef CONFIG_SYSCTL
 550         if (!brnf_call_iptables)
 551                 return NF_ACCEPT;
 552 #endif
 553
 554         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 555             !IS_PPPOE_IP(skb))
 556                 return NF_ACCEPT;
 557
 558         nf_bridge_pull_encap_header_rcsum(skb);
 559
 560         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 561                 goto inhdr_error;
 562
 563         iph = ip_hdr(skb);
 564         if (iph->ihl < 5 || iph->version != 4)
 565                 goto inhdr_error;
 566
 567         if (!pskb_may_pull(skb, 4 * iph->ihl))
 568                 goto inhdr_error;
 569
 570         iph = ip_hdr(skb);
 571         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
 572                 goto inhdr_error;
 573
 574         len = ntohs(iph->tot_len);
 575         if (skb->len < len || len < 4 * iph->ihl)
 576                 goto inhdr_error;
 577
 578         pskb_trim_rcsum(skb, len);
 579
 580         nf_bridge_put(skb->nf_bridge);
 581         if (!nf_bridge_alloc(skb))
 582                 return NF_DROP;
 583         if (!setup_pre_routing(skb))
 584                 return NF_DROP;
 585         store_orig_dstaddr(skb);
 586
 587         NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 588                 br_nf_pre_routing_finish);
 589
 590         return NF_STOLEN;
 591
 592 inhdr_error:
 593 //      IP_INC_STATS_BH(IpInHdrErrors);
 594 out:
 595         return NF_DROP;
 596 }
 597
 598
 599 /* PF_BRIDGE/LOCAL_IN ************************************************/
 600 /* The packet is locally destined, which requires a real
 601  * dst_entry, so detach the fake one.  On the way up, the
 602  * packet would pass through PRE_ROUTING again (which already
 603  * took place when the packet entered the bridge), but we
 604  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 605  * prevent this from happening. */
 606 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 607                                    const struct net_device *in,
 608                                    const struct net_device *out,
 609                                    int (*okfn)(struct sk_buff *))
 610 {
 611         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
 612                 dst_release(skb->dst);
 613                 skb->dst = NULL;
 614         }
 615
 616         return NF_ACCEPT;
 617 }
 618
 619 /* PF_BRIDGE/FORWARD *************************************************/
 620 static int br_nf_forward_finish(struct sk_buff *skb)
 621 {
 622         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 623         struct net_device *in;
 624
 625         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 626                 in = nf_bridge->physindev;
 627                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 628                         skb->pkt_type = PACKET_OTHERHOST;
 629                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 630                 }
 631         } else {
 632                 in = *((struct net_device **)(skb->cb));
 633         }
 634         nf_bridge_push_encap_header(skb);
 635         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
 636                        skb->dev, br_forward_finish, 1);
 637         return 0;
 638 }
 639
 640 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 641  * netfilter with indev and outdev set to the bridge device,
 642  * but we are still able to filter on the 'real' indev/outdev
 643  * because of the physdev module. For ARP, indev and outdev are the
 644  * bridge ports. */
 645 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 646                                      const struct net_device *in,
 647                                      const struct net_device *out,
 648                                      int (*okfn)(struct sk_buff *))
 649 {
 650         struct nf_bridge_info *nf_bridge;
 651         struct net_device *parent;
 652         int pf;
 653
 654         if (!skb->nf_bridge)
 655                 return NF_ACCEPT;
 656
 657         /* Need exclusive nf_bridge_info since we might have multiple
 658          * different physoutdevs. */
 659         if (!nf_bridge_unshare(skb))
 660                 return NF_DROP;
 661
 662         parent = bridge_parent(out);
 663         if (!parent)
 664                 return NF_DROP;
 665
 666         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 667             IS_PPPOE_IP(skb))
 668                 pf = PF_INET;
 669         else
 670                 pf = PF_INET6;
 671
 672         nf_bridge_pull_encap_header(skb);
 673
 674         nf_bridge = skb->nf_bridge;
 675         if (skb->pkt_type == PACKET_OTHERHOST) {
 676                 skb->pkt_type = PACKET_HOST;
 677                 nf_bridge->mask |= BRNF_PKT_TYPE;
 678         }
 679
 680         /* The physdev module checks on this */
 681         nf_bridge->mask |= BRNF_BRIDGED;
 682         nf_bridge->physoutdev = skb->dev;
 683
 684         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 685                 br_nf_forward_finish);
 686
 687         return NF_STOLEN;
 688 }
 689
 690 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 691                                       const struct net_device *in,
 692                                       const struct net_device *out,
 693                                       int (*okfn)(struct sk_buff *))
 694 {
 695         struct net_device **d = (struct net_device **)(skb->cb);
 696
 697 #ifdef CONFIG_SYSCTL
 698         if (!brnf_call_arptables)
 699                 return NF_ACCEPT;
 700 #endif
 701
 702         if (skb->protocol != htons(ETH_P_ARP)) {
 703                 if (!IS_VLAN_ARP(skb))
 704                         return NF_ACCEPT;
 705                 nf_bridge_pull_encap_header(skb);
 706         }
 707
 708         if (arp_hdr(skb)->ar_pln != 4) {
 709                 if (IS_VLAN_ARP(skb))
 710                         nf_bridge_push_encap_header(skb);
 711                 return NF_ACCEPT;
 712         }
 713         *d = (struct net_device *)in;
 714         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 715                 (struct net_device *)out, br_nf_forward_finish);
 716
 717         return NF_STOLEN;
 718 }
 719
 720 /* PF_BRIDGE/LOCAL_OUT ***********************************************
 721  *
 722  * This function sees both locally originated IP packets and forwarded
 723  * IP packets (in both cases the destination device is a bridge
 724  * device). It also sees bridged-and-DNAT'ed packets.
 725  *
 726  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
 727  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
 728  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
 729  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
 730  * will be executed.
 731  */
 732 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff *skb,
 733                                     const struct net_device *in,
 734                                     const struct net_device *out,
 735                                     int (*okfn)(struct sk_buff *))
 736 {
 737         struct net_device *realindev;
 738         struct nf_bridge_info *nf_bridge;
 739
 740         if (!skb->nf_bridge)
 741                 return NF_ACCEPT;
 742
 743         /* Need exclusive nf_bridge_info since we might have multiple
 744          * different physoutdevs. */
 745         if (!nf_bridge_unshare(skb))
 746                 return NF_DROP;
 747
 748         nf_bridge = skb->nf_bridge;
 749         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
 750                 return NF_ACCEPT;
 751
 752         /* Bridged, take PF_BRIDGE/FORWARD.
 753          * (see big note in front of br_nf_pre_routing_finish) */
 754         nf_bridge->physoutdev = skb->dev;
 755         realindev = nf_bridge->physindev;
 756
 757         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 758                 skb->pkt_type = PACKET_OTHERHOST;
 759                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 760         }
 761         nf_bridge_push_encap_header(skb);
 762
 763         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
 764                 br_forward_finish);
 765         return NF_STOLEN;
 766 }
 767
 768 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 769 {
 770         if (skb->protocol == htons(ETH_P_IP) &&
 771             skb->len > skb->dev->mtu &&
 772             !skb_is_gso(skb))
 773                 return ip_fragment(skb, br_dev_queue_push_xmit);
 774         else
 775                 return br_dev_queue_push_xmit(skb);
 776 }
 777
 778 /* PF_BRIDGE/POST_ROUTING ********************************************/
 779 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 780                                        const struct net_device *in,
 781                                        const struct net_device *out,
 782                                        int (*okfn)(struct sk_buff *))
 783 {
 784         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 785         struct net_device *realoutdev = bridge_parent(skb->dev);
 786         int pf;
 787
 788 #ifdef CONFIG_NETFILTER_DEBUG
 789         /* Be very paranoid. This probably won't happen anymore, but let's
 790          * keep the check just to be sure... */
 791         if (skb_mac_header(skb) < skb->head ||
 792             skb_mac_header(skb) + ETH_HLEN > skb->data) {
 793                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
 794                        "bad mac.raw pointer.\n");
 795                 goto print_error;
 796         }
 797 #endif
 798
 799         if (!nf_bridge)
 800                 return NF_ACCEPT;
 801
 802         if (!(nf_bridge->mask & (BRNF_BRIDGED | BRNF_BRIDGED_DNAT)))
 803                 return NF_ACCEPT;
 804
 805         if (!realoutdev)
 806                 return NF_DROP;
 807
 808         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 809             IS_PPPOE_IP(skb))
 810                 pf = PF_INET;
 811         else
 812                 pf = PF_INET6;
 813
 814 #ifdef CONFIG_NETFILTER_DEBUG
 815         if (skb->dst == NULL) {
 816                 printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
 817                 goto print_error;
 818         }
 819 #endif
 820
 821         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 822          * about the value of skb->pkt_type. */
 823         if (skb->pkt_type == PACKET_OTHERHOST) {
 824                 skb->pkt_type = PACKET_HOST;
 825                 nf_bridge->mask |= BRNF_PKT_TYPE;
 826         }
 827
 828         nf_bridge_pull_encap_header(skb);
 829         nf_bridge_save_header(skb);
 830
 831 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
 832         if (nf_bridge->netoutdev)
 833                 realoutdev = nf_bridge->netoutdev;
 834 #endif
 835         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 836                 br_nf_dev_queue_xmit);
 837
 838         return NF_STOLEN;
 839
 840 #ifdef CONFIG_NETFILTER_DEBUG
 841 print_error:
 842         if (skb->dev != NULL) {
 843                 printk("[%s]", skb->dev->name);
 844                 if (realoutdev)
 845                         printk("[%s]", realoutdev->name);
 846         }
 847         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb),
 848                skb->data);
 849         dump_stack();
 850         return NF_ACCEPT;
 851 #endif
 852 }
 853
 854 /* IP/SABOTAGE *****************************************************/
 855 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 856  * for the second time. */
 857 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 858                                    const struct net_device *in,
 859                                    const struct net_device *out,
 860                                    int (*okfn)(struct sk_buff *))
 861 {
 862         if (skb->nf_bridge &&
 863             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 864                 return NF_STOP;
 865         }
 866
 867         return NF_ACCEPT;
 868 }
 869
 870 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
 871  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
 872  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 873  * ip_refrag() can return NF_STOLEN. */
 874 static struct nf_hook_ops br_nf_ops[] = {
 875         { .hook = br_nf_pre_routing,
 876           .owner = THIS_MODULE,
 877           .pf = PF_BRIDGE,
 878           .hooknum = NF_BR_PRE_ROUTING,
 879           .priority = NF_BR_PRI_BRNF, },
 880         { .hook = br_nf_local_in,
 881           .owner = THIS_MODULE,
 882           .pf = PF_BRIDGE,
 883           .hooknum = NF_BR_LOCAL_IN,
 884           .priority = NF_BR_PRI_BRNF, },
 885         { .hook = br_nf_forward_ip,
 886           .owner = THIS_MODULE,
 887           .pf = PF_BRIDGE,
 888           .hooknum = NF_BR_FORWARD,
 889           .priority = NF_BR_PRI_BRNF - 1, },
 890         { .hook = br_nf_forward_arp,
 891           .owner = THIS_MODULE,
 892           .pf = PF_BRIDGE,
 893           .hooknum = NF_BR_FORWARD,
 894           .priority = NF_BR_PRI_BRNF, },
 895         { .hook = br_nf_local_out,
 896           .owner = THIS_MODULE,
 897           .pf = PF_BRIDGE,
 898           .hooknum = NF_BR_LOCAL_OUT,
 899           .priority = NF_BR_PRI_FIRST, },
 900         { .hook = br_nf_post_routing,
 901           .owner = THIS_MODULE,
 902           .pf = PF_BRIDGE,
 903           .hooknum = NF_BR_POST_ROUTING,
 904           .priority = NF_BR_PRI_LAST, },
 905         { .hook = ip_sabotage_in,
 906           .owner = THIS_MODULE,
 907           .pf = PF_INET,
 908           .hooknum = NF_INET_PRE_ROUTING,
 909           .priority = NF_IP_PRI_FIRST, },
 910         { .hook = ip_sabotage_in,
 911           .owner = THIS_MODULE,
 912           .pf = PF_INET6,
 913           .hooknum = NF_INET_PRE_ROUTING,
 914           .priority = NF_IP6_PRI_FIRST, },
 915 };
 916
 917 #ifdef CONFIG_SYSCTL
 918 static
 919 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
 920                             void __user * buffer, size_t * lenp, loff_t * ppos)
 921 {
 922         int ret;
 923
 924         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
 925
 926         if (write && *(int *)(ctl->data))
 927                 *(int *)(ctl->data) = 1;
 928         return ret;
 929 }
 930
 931 static ctl_table brnf_table[] = {
 932         {
 933                 .procname       = "bridge-nf-call-arptables",
 934                 .data           = &brnf_call_arptables,
 935                 .maxlen         = sizeof(int),
 936                 .mode           = 0644,
 937                 .proc_handler   = &brnf_sysctl_call_tables,
 938         },
 939         {
 940                 .procname       = "bridge-nf-call-iptables",
 941                 .data           = &brnf_call_iptables,
 942                 .maxlen         = sizeof(int),
 943                 .mode           = 0644,
 944                 .proc_handler   = &brnf_sysctl_call_tables,
 945         },
 946         {
 947                 .procname       = "bridge-nf-call-ip6tables",
 948                 .data           = &brnf_call_ip6tables,
 949                 .maxlen         = sizeof(int),
 950                 .mode           = 0644,
 951                 .proc_handler   = &brnf_sysctl_call_tables,
 952         },
 953         {
 954                 .procname       = "bridge-nf-filter-vlan-tagged",
 955                 .data           = &brnf_filter_vlan_tagged,
 956                 .maxlen         = sizeof(int),
 957                 .mode           = 0644,
 958                 .proc_handler   = &brnf_sysctl_call_tables,
 959         },
 960         {
 961                 .procname       = "bridge-nf-filter-pppoe-tagged",
 962                 .data           = &brnf_filter_pppoe_tagged,
 963                 .maxlen         = sizeof(int),
 964                 .mode           = 0644,
 965                 .proc_handler   = &brnf_sysctl_call_tables,
 966         },
 967         { .ctl_name = 0 }
 968 };
 969
 970 static ctl_table brnf_bridge_table[] = {
 971         {
 972                 .ctl_name       = NET_BRIDGE,
 973                 .procname       = "bridge",
 974                 .mode           = 0555,
 975                 .child          = brnf_table,
 976         },
 977         { .ctl_name = 0 }
 978 };
 979
 980 static ctl_table brnf_net_table[] = {
 981         {
 982                 .ctl_name       = CTL_NET,
 983                 .procname       = "net",
 984                 .mode           = 0555,
 985                 .child          = brnf_bridge_table,
 986         },
 987         { .ctl_name = 0 }
 988 };
 989 #endif
 990
 991 int __init br_netfilter_init(void)
 992 {
 993         int ret;
 994
 995         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
 996         if (ret < 0)
 997                 return ret;
 998 #ifdef CONFIG_SYSCTL
 999         brnf_sysctl_header = register_sysctl_table(brnf_net_table);
1000         if (brnf_sysctl_header == NULL) {
1001                 printk(KERN_WARNING
1002                        "br_netfilter: can't register to sysctl.\n");
1003                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1004                 return -ENOMEM;
1005         }
1006 #endif
1007         printk(KERN_NOTICE "Bridge firewalling registered\n");
1008         return 0;
1009 }
1010
1011 void br_netfilter_fini(void)
1012 {
1013         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1014 #ifdef CONFIG_SYSCTL
1015         unregister_sysctl_table(brnf_sysctl_header);
1016 #endif
1017 }