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                <bdschuym@pandora.be>
   8  *
   9  *      This program is free software; you can redistribute it and/or
  10  *      modify it under the terms of the GNU General Public License
  11  *      as published by the Free Software Foundation; either version
  12  *      2 of the License, or (at your option) any later version.
  13  *
  14  *      Lennert dedicates this file to Kerstin Wurdinger.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/kernel.h>
  19 #include <linux/slab.h>
  20 #include <linux/ip.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/if_ether.h>
  25 #include <linux/if_vlan.h>
  26 #include <linux/if_pppox.h>
  27 #include <linux/ppp_defs.h>
  28 #include <linux/netfilter_bridge.h>
  29 #include <linux/netfilter_ipv4.h>
  30 #include <linux/netfilter_ipv6.h>
  31 #include <linux/netfilter_arp.h>
  32 #include <linux/in_route.h>
  33 #include <linux/inetdevice.h>
  34
  35 #include <net/ip.h>
  36 #include <net/ipv6.h>
  37 #include <net/route.h>
  38
  39 #include <asm/uaccess.h>
  40 #include "br_private.h"
  41 #ifdef CONFIG_SYSCTL
  42 #include <linux/sysctl.h>
  43 #endif
  44
  45 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  46                                  (skb->nf_bridge->data))->daddr.ipv4)
  47 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  48 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  49
  50 #ifdef CONFIG_SYSCTL
  51 static struct ctl_table_header *brnf_sysctl_header;
  52 static int brnf_call_iptables __read_mostly = 1;
  53 static int brnf_call_ip6tables __read_mostly = 1;
  54 static int brnf_call_arptables __read_mostly = 1;
  55 static int brnf_filter_vlan_tagged __read_mostly = 0;
  56 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  57 #else
  58 #define brnf_call_iptables 1
  59 #define brnf_call_ip6tables 1
  60 #define brnf_call_arptables 1
  61 #define brnf_filter_vlan_tagged 0
  62 #define brnf_filter_pppoe_tagged 0
  63 #endif
  64
  65 static inline __be16 vlan_proto(const struct sk_buff *skb)
  66 {
  67         if (vlan_tx_tag_present(skb))
  68                 return skb->protocol;
  69         else if (skb->protocol == htons(ETH_P_8021Q))
  70                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  71         else
  72                 return 0;
  73 }
  74
  75 #define IS_VLAN_IP(skb) \
  76         (vlan_proto(skb) == htons(ETH_P_IP) && \
  77          brnf_filter_vlan_tagged)
  78
  79 #define IS_VLAN_IPV6(skb) \
  80         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  81          brnf_filter_vlan_tagged)
  82
  83 #define IS_VLAN_ARP(skb) \
  84         (vlan_proto(skb) == htons(ETH_P_ARP) && \
  85          brnf_filter_vlan_tagged)
  86
  87 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  88 {
  89         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  90                             sizeof(struct pppoe_hdr)));
  91 }
  92
  93 #define IS_PPPOE_IP(skb) \
  94         (skb->protocol == htons(ETH_P_PPP_SES) && \
  95          pppoe_proto(skb) == htons(PPP_IP) && \
  96          brnf_filter_pppoe_tagged)
  97
  98 #define IS_PPPOE_IPV6(skb) \
  99         (skb->protocol == htons(ETH_P_PPP_SES) && \
 100          pppoe_proto(skb) == htons(PPP_IPV6) && \
 101          brnf_filter_pppoe_tagged)
 102
 103 static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
 104 {
 105 }
 106
 107 static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
 108 {
 109         return NULL;
 110 }
 111
 112 static struct dst_ops fake_dst_ops = {
 113         .family =               AF_INET,
 114         .protocol =             cpu_to_be16(ETH_P_IP),
 115         .update_pmtu =          fake_update_pmtu,
 116         .cow_metrics =          fake_cow_metrics,
 117 };
 118
 119 /*
 120  * Initialize bogus route table used to keep netfilter happy.
 121  * Currently, we fill in the PMTU entry because netfilter
 122  * refragmentation needs it, and the rt_flags entry because
 123  * ipt_REJECT needs it.  Future netfilter modules might
 124  * require us to fill additional fields.
 125  */
 126 static const u32 br_dst_default_metrics[RTAX_MAX] = {
 127         [RTAX_MTU - 1] = 1500,
 128 };
 129
 130 void br_netfilter_rtable_init(struct net_bridge *br)
 131 {
 132         struct rtable *rt = &br->fake_rtable;
 133
 134         atomic_set(&rt->dst.__refcnt, 1);
 135         rt->dst.dev = br->dev;
 136         rt->dst.path = &rt->dst;
 137         dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
 138         rt->dst.flags   = DST_NOXFRM;
 139         rt->dst.ops = &fake_dst_ops;
 140 }
 141
 142 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 143 {
 144         struct net_bridge_port *port;
 145
 146         port = br_port_get_rcu(dev);
 147         return port ? &port->br->fake_rtable : NULL;
 148 }
 149
 150 static inline struct net_device *bridge_parent(const struct net_device *dev)
 151 {
 152         struct net_bridge_port *port;
 153
 154         port = br_port_get_rcu(dev);
 155         return port ? port->br->dev : NULL;
 156 }
 157
 158 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 159 {
 160         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 161         if (likely(skb->nf_bridge))
 162                 atomic_set(&(skb->nf_bridge->use), 1);
 163
 164         return skb->nf_bridge;
 165 }
 166
 167 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 168 {
 169         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 170
 171         if (atomic_read(&nf_bridge->use) > 1) {
 172                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 173
 174                 if (tmp) {
 175                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 176                         atomic_set(&tmp->use, 1);
 177                 }
 178                 nf_bridge_put(nf_bridge);
 179                 nf_bridge = tmp;
 180         }
 181         return nf_bridge;
 182 }
 183
 184 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 185 {
 186         unsigned int len = nf_bridge_encap_header_len(skb);
 187
 188         skb_push(skb, len);
 189         skb->network_header -= len;
 190 }
 191
 192 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 193 {
 194         unsigned int len = nf_bridge_encap_header_len(skb);
 195
 196         skb_pull(skb, len);
 197         skb->network_header += len;
 198 }
 199
 200 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 201 {
 202         unsigned int len = nf_bridge_encap_header_len(skb);
 203
 204         skb_pull_rcsum(skb, len);
 205         skb->network_header += len;
 206 }
 207
 208 static inline void nf_bridge_save_header(struct sk_buff *skb)
 209 {
 210         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 211
 212         skb_copy_from_linear_data_offset(skb, -header_size,
 213                                          skb->nf_bridge->data, header_size);
 214 }
 215
 216 static inline void nf_bridge_update_protocol(struct sk_buff *skb)
 217 {
 218         if (skb->nf_bridge->mask & BRNF_8021Q)
 219                 skb->protocol = htons(ETH_P_8021Q);
 220         else if (skb->nf_bridge->mask & BRNF_PPPoE)
 221                 skb->protocol = htons(ETH_P_PPP_SES);
 222 }
 223
 224 /* When handing a packet over to the IP layer
 225  * check whether we have a skb that is in the
 226  * expected format
 227  */
 228
 229 static int br_parse_ip_options(struct sk_buff *skb)
 230 {
 231         struct ip_options *opt;
 232         const struct iphdr *iph;
 233         struct net_device *dev = skb->dev;
 234         u32 len;
 235
 236         iph = ip_hdr(skb);
 237         opt = &(IPCB(skb)->opt);
 238
 239         /* Basic sanity checks */
 240         if (iph->ihl < 5 || iph->version != 4)
 241                 goto inhdr_error;
 242
 243         if (!pskb_may_pull(skb, iph->ihl*4))
 244                 goto inhdr_error;
 245
 246         iph = ip_hdr(skb);
 247         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 248                 goto inhdr_error;
 249
 250         len = ntohs(iph->tot_len);
 251         if (skb->len < len) {
 252                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 253                 goto drop;
 254         } else if (len < (iph->ihl*4))
 255                 goto inhdr_error;
 256
 257         if (pskb_trim_rcsum(skb, len)) {
 258                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 259                 goto drop;
 260         }
 261
 262         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 263         if (iph->ihl == 5)
 264                 return 0;
 265
 266         opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 267         if (ip_options_compile(dev_net(dev), opt, skb))
 268                 goto inhdr_error;
 269
 270         /* Check correct handling of SRR option */
 271         if (unlikely(opt->srr)) {
 272                 struct in_device *in_dev = __in_dev_get_rcu(dev);
 273                 if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
 274                         goto drop;
 275
 276                 if (ip_options_rcv_srr(skb))
 277                         goto drop;
 278         }
 279
 280         return 0;
 281
 282 inhdr_error:
 283         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 284 drop:
 285         return -1;
 286 }
 287
 288 /* Fill in the header for fragmented IP packets handled by
 289  * the IPv4 connection tracking code.
 290  */
 291 int nf_bridge_copy_header(struct sk_buff *skb)
 292 {
 293         int err;
 294         unsigned int header_size;
 295
 296         nf_bridge_update_protocol(skb);
 297         header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 298         err = skb_cow_head(skb, header_size);
 299         if (err)
 300                 return err;
 301
 302         skb_copy_to_linear_data_offset(skb, -header_size,
 303                                        skb->nf_bridge->data, header_size);
 304         __skb_push(skb, nf_bridge_encap_header_len(skb));
 305         return 0;
 306 }
 307
 308 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 309 /* Undo the changes made for ip6tables PREROUTING and continue the
 310  * bridge PRE_ROUTING hook. */
 311 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 312 {
 313         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 314         struct rtable *rt;
 315
 316         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 317                 skb->pkt_type = PACKET_OTHERHOST;
 318                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 319         }
 320         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 321
 322         rt = bridge_parent_rtable(nf_bridge->physindev);
 323         if (!rt) {
 324                 kfree_skb(skb);
 325                 return 0;
 326         }
 327         skb_dst_set_noref(skb, &rt->dst);
 328
 329         skb->dev = nf_bridge->physindev;
 330         nf_bridge_update_protocol(skb);
 331         nf_bridge_push_encap_header(skb);
 332         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 333                        br_handle_frame_finish, 1);
 334
 335         return 0;
 336 }
 337
 338 /* Obtain the correct destination MAC address, while preserving the original
 339  * source MAC address. If we already know this address, we just copy it. If we
 340  * don't, we use the neighbour framework to find out. In both cases, we make
 341  * sure that br_handle_frame_finish() is called afterwards.
 342  */
 343 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 344 {
 345         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 346         struct dst_entry *dst;
 347
 348         skb->dev = bridge_parent(skb->dev);
 349         if (!skb->dev)
 350                 goto free_skb;
 351         dst = skb_dst(skb);
 352         if (dst->hh) {
 353                 neigh_hh_bridge(dst->hh, skb);
 354                 skb->dev = nf_bridge->physindev;
 355                 return br_handle_frame_finish(skb);
 356         } else if (dst->neighbour) {
 357                 /* the neighbour function below overwrites the complete
 358                  * MAC header, so we save the Ethernet source address and
 359                  * protocol number. */
 360                 skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
 361                 /* tell br_dev_xmit to continue with forwarding */
 362                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 363                 return dst->neighbour->output(skb);
 364         }
 365 free_skb:
 366         kfree_skb(skb);
 367         return 0;
 368 }
 369
 370 /* This requires some explaining. If DNAT has taken place,
 371  * we will need to fix up the destination Ethernet address.
 372  *
 373  * There are two cases to consider:
 374  * 1. The packet was DNAT'ed to a device in the same bridge
 375  *    port group as it was received on. We can still bridge
 376  *    the packet.
 377  * 2. The packet was DNAT'ed to a different device, either
 378  *    a non-bridged device or another bridge port group.
 379  *    The packet will need to be routed.
 380  *
 381  * The correct way of distinguishing between these two cases is to
 382  * call ip_route_input() and to look at skb->dst->dev, which is
 383  * changed to the destination device if ip_route_input() succeeds.
 384  *
 385  * Let's first consider the case that ip_route_input() succeeds:
 386  *
 387  * If the output device equals the logical bridge device the packet
 388  * came in on, we can consider this bridging. The corresponding MAC
 389  * address will be obtained in br_nf_pre_routing_finish_bridge.
 390  * Otherwise, the packet is considered to be routed and we just
 391  * change the destination MAC address so that the packet will
 392  * later be passed up to the IP stack to be routed. For a redirected
 393  * packet, ip_route_input() will give back the localhost as output device,
 394  * which differs from the bridge device.
 395  *
 396  * Let's now consider the case that ip_route_input() fails:
 397  *
 398  * This can be because the destination address is martian, in which case
 399  * the packet will be dropped.
 400  * If IP forwarding is disabled, ip_route_input() will fail, while
 401  * ip_route_output_key() can return success. The source
 402  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 403  * thinks we're handling a locally generated packet and won't care
 404  * if IP forwarding is enabled. If the output device equals the logical bridge
 405  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 406  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 407  */
 408 static int br_nf_pre_routing_finish(struct sk_buff *skb)
 409 {
 410         struct net_device *dev = skb->dev;
 411         struct iphdr *iph = ip_hdr(skb);
 412         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 413         struct rtable *rt;
 414         int err;
 415
 416         if (nf_bridge->mask & BRNF_PKT_TYPE) {
 417                 skb->pkt_type = PACKET_OTHERHOST;
 418                 nf_bridge->mask ^= BRNF_PKT_TYPE;
 419         }
 420         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 421         if (dnat_took_place(skb)) {
 422                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 423                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 424
 425                         /* If err equals -EHOSTUNREACH the error is due to a
 426                          * martian destination or due to the fact that
 427                          * forwarding is disabled. For most martian packets,
 428                          * ip_route_output_key() will fail. It won't fail for 2 types of
 429                          * martian destinations: loopback destinations and destination
 430                          * 0.0.0.0. In both cases the packet will be dropped because the
 431                          * destination is the loopback device and not the bridge. */
 432                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 433                                 goto free_skb;
 434
 435                         rt = ip_route_output(dev_net(dev), iph->daddr, 0,
 436                                              RT_TOS(iph->tos), 0);
 437                         if (!IS_ERR(rt)) {
 438                                 /* - Bridged-and-DNAT'ed traffic doesn't
 439                                  *   require ip_forwarding. */
 440                                 if (rt->dst.dev == dev) {
 441                                         skb_dst_set(skb, &rt->dst);
 442                                         goto bridged_dnat;
 443                                 }
 444                                 ip_rt_put(rt);
 445                         }
 446 free_skb:
 447                         kfree_skb(skb);
 448                         return 0;
 449                 } else {
 450                         if (skb_dst(skb)->dev == dev) {
 451 bridged_dnat:
 452                                 skb->dev = nf_bridge->physindev;
 453                                 nf_bridge_update_protocol(skb);
 454                                 nf_bridge_push_encap_header(skb);
 455                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 456                                                NF_BR_PRE_ROUTING,
 457                                                skb, skb->dev, NULL,
 458                                                br_nf_pre_routing_finish_bridge,
 459                                                1);
 460                                 return 0;
 461                         }
 462                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 463                         skb->pkt_type = PACKET_HOST;
 464                 }
 465         } else {
 466                 rt = bridge_parent_rtable(nf_bridge->physindev);
 467                 if (!rt) {
 468                         kfree_skb(skb);
 469                         return 0;
 470                 }
 471                 skb_dst_set_noref(skb, &rt->dst);
 472         }
 473
 474         skb->dev = nf_bridge->physindev;
 475         nf_bridge_update_protocol(skb);
 476         nf_bridge_push_encap_header(skb);
 477         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 478                        br_handle_frame_finish, 1);
 479
 480         return 0;
 481 }
 482
 483 /* Some common code for IPv4/IPv6 */
 484 static struct net_device *setup_pre_routing(struct sk_buff *skb)
 485 {
 486         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 487
 488         if (skb->pkt_type == PACKET_OTHERHOST) {
 489                 skb->pkt_type = PACKET_HOST;
 490                 nf_bridge->mask |= BRNF_PKT_TYPE;
 491         }
 492
 493         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 494         nf_bridge->physindev = skb->dev;
 495         skb->dev = bridge_parent(skb->dev);
 496         if (skb->protocol == htons(ETH_P_8021Q))
 497                 nf_bridge->mask |= BRNF_8021Q;
 498         else if (skb->protocol == htons(ETH_P_PPP_SES))
 499                 nf_bridge->mask |= BRNF_PPPoE;
 500
 501         return skb->dev;
 502 }
 503
 504 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 505 static int check_hbh_len(struct sk_buff *skb)
 506 {
 507         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 508         u32 pkt_len;
 509         const unsigned char *nh = skb_network_header(skb);
 510         int off = raw - nh;
 511         int len = (raw[1] + 1) << 3;
 512
 513         if ((raw + len) - skb->data > skb_headlen(skb))
 514                 goto bad;
 515
 516         off += 2;
 517         len -= 2;
 518
 519         while (len > 0) {
 520                 int optlen = nh[off + 1] + 2;
 521
 522                 switch (nh[off]) {
 523                 case IPV6_TLV_PAD0:
 524                         optlen = 1;
 525                         break;
 526
 527                 case IPV6_TLV_PADN:
 528                         break;
 529
 530                 case IPV6_TLV_JUMBO:
 531                         if (nh[off + 1] != 4 || (off & 3) != 2)
 532                                 goto bad;
 533                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 534                         if (pkt_len <= IPV6_MAXPLEN ||
 535                             ipv6_hdr(skb)->payload_len)
 536                                 goto bad;
 537                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 538                                 goto bad;
 539                         if (pskb_trim_rcsum(skb,
 540                                             pkt_len + sizeof(struct ipv6hdr)))
 541                                 goto bad;
 542                         nh = skb_network_header(skb);
 543                         break;
 544                 default:
 545                         if (optlen > len)
 546                                 goto bad;
 547                         break;
 548                 }
 549                 off += optlen;
 550                 len -= optlen;
 551         }
 552         if (len == 0)
 553                 return 0;
 554 bad:
 555         return -1;
 556
 557 }
 558
 559 /* Replicate the checks that IPv6 does on packet reception and pass the packet
 560  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 561 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 562                                            struct sk_buff *skb,
 563                                            const struct net_device *in,
 564                                            const struct net_device *out,
 565                                            int (*okfn)(struct sk_buff *))
 566 {
 567         const struct ipv6hdr *hdr;
 568         u32 pkt_len;
 569
 570         if (skb->len < sizeof(struct ipv6hdr))
 571                 return NF_DROP;
 572
 573         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 574                 return NF_DROP;
 575
 576         hdr = ipv6_hdr(skb);
 577
 578         if (hdr->version != 6)
 579                 return NF_DROP;
 580
 581         pkt_len = ntohs(hdr->payload_len);
 582
 583         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 584                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 585                         return NF_DROP;
 586                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 587                         return NF_DROP;
 588         }
 589         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 590                 return NF_DROP;
 591
 592         nf_bridge_put(skb->nf_bridge);
 593         if (!nf_bridge_alloc(skb))
 594                 return NF_DROP;
 595         if (!setup_pre_routing(skb))
 596                 return NF_DROP;
 597
 598         skb->protocol = htons(ETH_P_IPV6);
 599         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 600                 br_nf_pre_routing_finish_ipv6);
 601
 602         return NF_STOLEN;
 603 }
 604
 605 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 606  * Replicate the checks that IPv4 does on packet reception.
 607  * Set skb->dev to the bridge device (i.e. parent of the
 608  * receiving device) to make netfilter happy, the REDIRECT
 609  * target in particular.  Save the original destination IP
 610  * address to be able to detect DNAT afterwards. */
 611 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 612                                       const struct net_device *in,
 613                                       const struct net_device *out,
 614                                       int (*okfn)(struct sk_buff *))
 615 {
 616         struct net_bridge_port *p;
 617         struct net_bridge *br;
 618         __u32 len = nf_bridge_encap_header_len(skb);
 619
 620         if (unlikely(!pskb_may_pull(skb, len)))
 621                 return NF_DROP;
 622
 623         p = br_port_get_rcu(in);
 624         if (p == NULL)
 625                 return NF_DROP;
 626         br = p->br;
 627
 628         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 629             IS_PPPOE_IPV6(skb)) {
 630                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 631                         return NF_ACCEPT;
 632
 633                 nf_bridge_pull_encap_header_rcsum(skb);
 634                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 635         }
 636
 637         if (!brnf_call_iptables && !br->nf_call_iptables)
 638                 return NF_ACCEPT;
 639
 640         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
 641             !IS_PPPOE_IP(skb))
 642                 return NF_ACCEPT;
 643
 644         nf_bridge_pull_encap_header_rcsum(skb);
 645
 646         if (br_parse_ip_options(skb))
 647                 return NF_DROP;
 648
 649         nf_bridge_put(skb->nf_bridge);
 650         if (!nf_bridge_alloc(skb))
 651                 return NF_DROP;
 652         if (!setup_pre_routing(skb))
 653                 return NF_DROP;
 654         store_orig_dstaddr(skb);
 655         skb->protocol = htons(ETH_P_IP);
 656
 657         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 658                 br_nf_pre_routing_finish);
 659
 660         return NF_STOLEN;
 661 }
 662
 663
 664 /* PF_BRIDGE/LOCAL_IN ************************************************/
 665 /* The packet is locally destined, which requires a real
 666  * dst_entry, so detach the fake one.  On the way up, the
 667  * packet would pass through PRE_ROUTING again (which already
 668  * took place when the packet entered the bridge), but we
 669  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 670  * prevent this from happening. */
 671 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 672                                    const struct net_device *in,
 673                                    const struct net_device *out,
 674                                    int (*okfn)(struct sk_buff *))
 675 {
 676         struct rtable *rt = skb_rtable(skb);
 677
 678         if (rt && rt == bridge_parent_rtable(in))
 679                 skb_dst_drop(skb);
 680
 681         return NF_ACCEPT;
 682 }
 683
 684 /* PF_BRIDGE/FORWARD *************************************************/
 685 static int br_nf_forward_finish(struct sk_buff *skb)
 686 {
 687         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 688         struct net_device *in;
 689
 690         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
 691                 in = nf_bridge->physindev;
 692                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
 693                         skb->pkt_type = PACKET_OTHERHOST;
 694                         nf_bridge->mask ^= BRNF_PKT_TYPE;
 695                 }
 696                 nf_bridge_update_protocol(skb);
 697         } else {
 698                 in = *((struct net_device **)(skb->cb));
 699         }
 700         nf_bridge_push_encap_header(skb);
 701
 702         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 703                        skb->dev, br_forward_finish, 1);
 704         return 0;
 705 }
 706
 707 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 708  * netfilter with indev and outdev set to the bridge device,
 709  * but we are still able to filter on the 'real' indev/outdev
 710  * because of the physdev module. For ARP, indev and outdev are the
 711  * bridge ports. */
 712 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 713                                      const struct net_device *in,
 714                                      const struct net_device *out,
 715                                      int (*okfn)(struct sk_buff *))
 716 {
 717         struct nf_bridge_info *nf_bridge;
 718         struct net_device *parent;
 719         u_int8_t pf;
 720
 721         if (!skb->nf_bridge)
 722                 return NF_ACCEPT;
 723
 724         /* Need exclusive nf_bridge_info since we might have multiple
 725          * different physoutdevs. */
 726         if (!nf_bridge_unshare(skb))
 727                 return NF_DROP;
 728
 729         parent = bridge_parent(out);
 730         if (!parent)
 731                 return NF_DROP;
 732
 733         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 734             IS_PPPOE_IP(skb))
 735                 pf = PF_INET;
 736         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 737                  IS_PPPOE_IPV6(skb))
 738                 pf = PF_INET6;
 739         else
 740                 return NF_ACCEPT;
 741
 742         nf_bridge_pull_encap_header(skb);
 743
 744         nf_bridge = skb->nf_bridge;
 745         if (skb->pkt_type == PACKET_OTHERHOST) {
 746                 skb->pkt_type = PACKET_HOST;
 747                 nf_bridge->mask |= BRNF_PKT_TYPE;
 748         }
 749
 750         if (pf == PF_INET && br_parse_ip_options(skb))
 751                 return NF_DROP;
 752
 753         /* The physdev module checks on this */
 754         nf_bridge->mask |= BRNF_BRIDGED;
 755         nf_bridge->physoutdev = skb->dev;
 756         if (pf == PF_INET)
 757                 skb->protocol = htons(ETH_P_IP);
 758         else
 759                 skb->protocol = htons(ETH_P_IPV6);
 760
 761         NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
 762                 br_nf_forward_finish);
 763
 764         return NF_STOLEN;
 765 }
 766
 767 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 768                                       const struct net_device *in,
 769                                       const struct net_device *out,
 770                                       int (*okfn)(struct sk_buff *))
 771 {
 772         struct net_bridge_port *p;
 773         struct net_bridge *br;
 774         struct net_device **d = (struct net_device **)(skb->cb);
 775
 776         p = br_port_get_rcu(out);
 777         if (p == NULL)
 778                 return NF_ACCEPT;
 779         br = p->br;
 780
 781         if (!brnf_call_arptables && !br->nf_call_arptables)
 782                 return NF_ACCEPT;
 783
 784         if (skb->protocol != htons(ETH_P_ARP)) {
 785                 if (!IS_VLAN_ARP(skb))
 786                         return NF_ACCEPT;
 787                 nf_bridge_pull_encap_header(skb);
 788         }
 789
 790         if (arp_hdr(skb)->ar_pln != 4) {
 791                 if (IS_VLAN_ARP(skb))
 792                         nf_bridge_push_encap_header(skb);
 793                 return NF_ACCEPT;
 794         }
 795         *d = (struct net_device *)in;
 796         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 797                 (struct net_device *)out, br_nf_forward_finish);
 798
 799         return NF_STOLEN;
 800 }
 801
 802 #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
 803 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 804 {
 805         int ret;
 806
 807         if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
 808             skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
 809             !skb_is_gso(skb)) {
 810                 if (br_parse_ip_options(skb))
 811                         /* Drop invalid packet */
 812                         return NF_DROP;
 813                 ret = ip_fragment(skb, br_dev_queue_push_xmit);
 814         } else
 815                 ret = br_dev_queue_push_xmit(skb);
 816
 817         return ret;
 818 }
 819 #else
 820 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 821 {
 822         return br_dev_queue_push_xmit(skb);
 823 }
 824 #endif
 825
 826 /* PF_BRIDGE/POST_ROUTING ********************************************/
 827 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 828                                        const struct net_device *in,
 829                                        const struct net_device *out,
 830                                        int (*okfn)(struct sk_buff *))
 831 {
 832         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 833         struct net_device *realoutdev = bridge_parent(skb->dev);
 834         u_int8_t pf;
 835
 836         if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 837                 return NF_ACCEPT;
 838
 839         if (!realoutdev)
 840                 return NF_DROP;
 841
 842         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
 843             IS_PPPOE_IP(skb))
 844                 pf = PF_INET;
 845         else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
 846                  IS_PPPOE_IPV6(skb))
 847                 pf = PF_INET6;
 848         else
 849                 return NF_ACCEPT;
 850
 851         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 852          * about the value of skb->pkt_type. */
 853         if (skb->pkt_type == PACKET_OTHERHOST) {
 854                 skb->pkt_type = PACKET_HOST;
 855                 nf_bridge->mask |= BRNF_PKT_TYPE;
 856         }
 857
 858         nf_bridge_pull_encap_header(skb);
 859         nf_bridge_save_header(skb);
 860         if (pf == PF_INET)
 861                 skb->protocol = htons(ETH_P_IP);
 862         else
 863                 skb->protocol = htons(ETH_P_IPV6);
 864
 865         NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 866                 br_nf_dev_queue_xmit);
 867
 868         return NF_STOLEN;
 869 }
 870
 871 /* IP/SABOTAGE *****************************************************/
 872 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 873  * for the second time. */
 874 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 875                                    const struct net_device *in,
 876                                    const struct net_device *out,
 877                                    int (*okfn)(struct sk_buff *))
 878 {
 879         if (skb->nf_bridge &&
 880             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 881                 return NF_STOP;
 882         }
 883
 884         return NF_ACCEPT;
 885 }
 886
 887 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 888  * br_dev_queue_push_xmit is called afterwards */
 889 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 890         {
 891                 .hook = br_nf_pre_routing,
 892                 .owner = THIS_MODULE,
 893                 .pf = PF_BRIDGE,
 894                 .hooknum = NF_BR_PRE_ROUTING,
 895                 .priority = NF_BR_PRI_BRNF,
 896         },
 897         {
 898                 .hook = br_nf_local_in,
 899                 .owner = THIS_MODULE,
 900                 .pf = PF_BRIDGE,
 901                 .hooknum = NF_BR_LOCAL_IN,
 902                 .priority = NF_BR_PRI_BRNF,
 903         },
 904         {
 905                 .hook = br_nf_forward_ip,
 906                 .owner = THIS_MODULE,
 907                 .pf = PF_BRIDGE,
 908                 .hooknum = NF_BR_FORWARD,
 909                 .priority = NF_BR_PRI_BRNF - 1,
 910         },
 911         {
 912                 .hook = br_nf_forward_arp,
 913                 .owner = THIS_MODULE,
 914                 .pf = PF_BRIDGE,
 915                 .hooknum = NF_BR_FORWARD,
 916                 .priority = NF_BR_PRI_BRNF,
 917         },
 918         {
 919                 .hook = br_nf_post_routing,
 920                 .owner = THIS_MODULE,
 921                 .pf = PF_BRIDGE,
 922                 .hooknum = NF_BR_POST_ROUTING,
 923                 .priority = NF_BR_PRI_LAST,
 924         },
 925         {
 926                 .hook = ip_sabotage_in,
 927                 .owner = THIS_MODULE,
 928                 .pf = PF_INET,
 929                 .hooknum = NF_INET_PRE_ROUTING,
 930                 .priority = NF_IP_PRI_FIRST,
 931         },
 932         {
 933                 .hook = ip_sabotage_in,
 934                 .owner = THIS_MODULE,
 935                 .pf = PF_INET6,
 936                 .hooknum = NF_INET_PRE_ROUTING,
 937                 .priority = NF_IP6_PRI_FIRST,
 938         },
 939 };
 940
 941 #ifdef CONFIG_SYSCTL
 942 static
 943 int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 944                             void __user * buffer, size_t * lenp, loff_t * ppos)
 945 {
 946         int ret;
 947
 948         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 949
 950         if (write && *(int *)(ctl->data))
 951                 *(int *)(ctl->data) = 1;
 952         return ret;
 953 }
 954
 955 static ctl_table brnf_table[] = {
 956         {
 957                 .procname       = "bridge-nf-call-arptables",
 958                 .data           = &brnf_call_arptables,
 959                 .maxlen         = sizeof(int),
 960                 .mode           = 0644,
 961                 .proc_handler   = brnf_sysctl_call_tables,
 962         },
 963         {
 964                 .procname       = "bridge-nf-call-iptables",
 965                 .data           = &brnf_call_iptables,
 966                 .maxlen         = sizeof(int),
 967                 .mode           = 0644,
 968                 .proc_handler   = brnf_sysctl_call_tables,
 969         },
 970         {
 971                 .procname       = "bridge-nf-call-ip6tables",
 972                 .data           = &brnf_call_ip6tables,
 973                 .maxlen         = sizeof(int),
 974                 .mode           = 0644,
 975                 .proc_handler   = brnf_sysctl_call_tables,
 976         },
 977         {
 978                 .procname       = "bridge-nf-filter-vlan-tagged",
 979                 .data           = &brnf_filter_vlan_tagged,
 980                 .maxlen         = sizeof(int),
 981                 .mode           = 0644,
 982                 .proc_handler   = brnf_sysctl_call_tables,
 983         },
 984         {
 985                 .procname       = "bridge-nf-filter-pppoe-tagged",
 986                 .data           = &brnf_filter_pppoe_tagged,
 987                 .maxlen         = sizeof(int),
 988                 .mode           = 0644,
 989                 .proc_handler   = brnf_sysctl_call_tables,
 990         },
 991         { }
 992 };
 993
 994 static struct ctl_path brnf_path[] = {
 995         { .procname = "net", },
 996         { .procname = "bridge", },
 997         { }
 998 };
 999 #endif
1000
1001 int __init br_netfilter_init(void)
1002 {
1003         int ret;
1004
1005         ret = dst_entries_init(&fake_dst_ops);
1006         if (ret < 0)
1007                 return ret;
1008
1009         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1010         if (ret < 0) {
1011                 dst_entries_destroy(&fake_dst_ops);
1012                 return ret;
1013         }
1014 #ifdef CONFIG_SYSCTL
1015         brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1016         if (brnf_sysctl_header == NULL) {
1017                 printk(KERN_WARNING
1018                        "br_netfilter: can't register to sysctl.\n");
1019                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1020                 dst_entries_destroy(&fake_dst_ops);
1021                 return -ENOMEM;
1022         }
1023 #endif
1024         printk(KERN_NOTICE "Bridge firewalling registered\n");
1025         return 0;
1026 }
1027
1028 void br_netfilter_fini(void)
1029 {
1030         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1031 #ifdef CONFIG_SYSCTL
1032         unregister_sysctl_table(brnf_sysctl_header);
1033 #endif
1034         dst_entries_destroy(&fake_dst_ops);
1035 }