kernel/net/bridge/br_netfilter_hooks.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/addrconf.h>
  38 #include <net/route.h>
  39 #include <net/netfilter/br_netfilter.h>
  40
  41 #include <asm/uaccess.h>
  42 #include "br_private.h"
  43 #ifdef CONFIG_SYSCTL
  44 #include <linux/sysctl.h>
  45 #endif
  46
  47 #ifdef CONFIG_SYSCTL
  48 static struct ctl_table_header *brnf_sysctl_header;
  49 static int brnf_call_iptables __read_mostly = 1;
  50 static int brnf_call_ip6tables __read_mostly = 1;
  51 static int brnf_call_arptables __read_mostly = 1;
  52 static int brnf_filter_vlan_tagged __read_mostly;
  53 static int brnf_filter_pppoe_tagged __read_mostly;
  54 static int brnf_pass_vlan_indev __read_mostly;
  55 #else
  56 #define brnf_call_iptables 1
  57 #define brnf_call_ip6tables 1
  58 #define brnf_call_arptables 1
  59 #define brnf_filter_vlan_tagged 0
  60 #define brnf_filter_pppoe_tagged 0
  61 #define brnf_pass_vlan_indev 0
  62 #endif
  63
  64 #define IS_IP(skb) \
  65         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
  66
  67 #define IS_IPV6(skb) \
  68         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
  69
  70 #define IS_ARP(skb) \
  71         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
  72
  73 static inline __be16 vlan_proto(const struct sk_buff *skb)
  74 {
  75         if (skb_vlan_tag_present(skb))
  76                 return skb->protocol;
  77         else if (skb->protocol == htons(ETH_P_8021Q))
  78                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  79         else
  80                 return 0;
  81 }
  82
  83 #define IS_VLAN_IP(skb) \
  84         (vlan_proto(skb) == htons(ETH_P_IP) && \
  85          brnf_filter_vlan_tagged)
  86
  87 #define IS_VLAN_IPV6(skb) \
  88         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  89          brnf_filter_vlan_tagged)
  90
  91 #define IS_VLAN_ARP(skb) \
  92         (vlan_proto(skb) == htons(ETH_P_ARP) && \
  93          brnf_filter_vlan_tagged)
  94
  95 static inline __be16 pppoe_proto(const struct sk_buff *skb)
  96 {
  97         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
  98                             sizeof(struct pppoe_hdr)));
  99 }
 100
 101 #define IS_PPPOE_IP(skb) \
 102         (skb->protocol == htons(ETH_P_PPP_SES) && \
 103          pppoe_proto(skb) == htons(PPP_IP) && \
 104          brnf_filter_pppoe_tagged)
 105
 106 #define IS_PPPOE_IPV6(skb) \
 107         (skb->protocol == htons(ETH_P_PPP_SES) && \
 108          pppoe_proto(skb) == htons(PPP_IPV6) && \
 109          brnf_filter_pppoe_tagged)
 110
 111 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
 112 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
 113
 114 struct brnf_frag_data {
 115         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
 116         u8 encap_size;
 117         u8 size;
 118         u16 vlan_tci;
 119         __be16 vlan_proto;
 120 };
 121
 122 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
 123
 124 static void nf_bridge_info_free(struct sk_buff *skb)
 125 {
 126         if (skb->nf_bridge) {
 127                 nf_bridge_put(skb->nf_bridge);
 128                 skb->nf_bridge = NULL;
 129         }
 130 }
 131
 132 static inline struct net_device *bridge_parent(const struct net_device *dev)
 133 {
 134         struct net_bridge_port *port;
 135
 136         port = br_port_get_rcu(dev);
 137         return port ? port->br->dev : NULL;
 138 }
 139
 140 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 141 {
 142         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 143
 144         if (atomic_read(&nf_bridge->use) > 1) {
 145                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 146
 147                 if (tmp) {
 148                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 149                         atomic_set(&tmp->use, 1);
 150                 }
 151                 nf_bridge_put(nf_bridge);
 152                 nf_bridge = tmp;
 153         }
 154         return nf_bridge;
 155 }
 156
 157 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
 158 {
 159         switch (skb->protocol) {
 160         case __cpu_to_be16(ETH_P_8021Q):
 161                 return VLAN_HLEN;
 162         case __cpu_to_be16(ETH_P_PPP_SES):
 163                 return PPPOE_SES_HLEN;
 164         default:
 165                 return 0;
 166         }
 167 }
 168
 169 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 170 {
 171         unsigned int len = nf_bridge_encap_header_len(skb);
 172
 173         skb_pull(skb, len);
 174         skb->network_header += len;
 175 }
 176
 177 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 178 {
 179         unsigned int len = nf_bridge_encap_header_len(skb);
 180
 181         skb_pull_rcsum(skb, len);
 182         skb->network_header += len;
 183 }
 184
 185 /* When handing a packet over to the IP layer
 186  * check whether we have a skb that is in the
 187  * expected format
 188  */
 189
 190 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
 191 {
 192         const struct iphdr *iph;
 193         u32 len;
 194
 195         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 196                 goto inhdr_error;
 197
 198         iph = ip_hdr(skb);
 199
 200         /* Basic sanity checks */
 201         if (iph->ihl < 5 || iph->version != 4)
 202                 goto inhdr_error;
 203
 204         if (!pskb_may_pull(skb, iph->ihl*4))
 205                 goto inhdr_error;
 206
 207         iph = ip_hdr(skb);
 208         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 209                 goto inhdr_error;
 210
 211         len = ntohs(iph->tot_len);
 212         if (skb->len < len) {
 213                 IP_INC_STATS_BH(net, IPSTATS_MIB_INTRUNCATEDPKTS);
 214                 goto drop;
 215         } else if (len < (iph->ihl*4))
 216                 goto inhdr_error;
 217
 218         if (pskb_trim_rcsum(skb, len)) {
 219                 IP_INC_STATS_BH(net, IPSTATS_MIB_INDISCARDS);
 220                 goto drop;
 221         }
 222
 223         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 224         /* We should really parse IP options here but until
 225          * somebody who actually uses IP options complains to
 226          * us we'll just silently ignore the options because
 227          * we're lazy!
 228          */
 229         return 0;
 230
 231 inhdr_error:
 232         IP_INC_STATS_BH(net, IPSTATS_MIB_INHDRERRORS);
 233 drop:
 234         return -1;
 235 }
 236
 237 void nf_bridge_update_protocol(struct sk_buff *skb)
 238 {
 239         switch (skb->nf_bridge->orig_proto) {
 240         case BRNF_PROTO_8021Q:
 241                 skb->protocol = htons(ETH_P_8021Q);
 242                 break;
 243         case BRNF_PROTO_PPPOE:
 244                 skb->protocol = htons(ETH_P_PPP_SES);
 245                 break;
 246         case BRNF_PROTO_UNCHANGED:
 247                 break;
 248         }
 249 }
 250
 251 /* Obtain the correct destination MAC address, while preserving the original
 252  * source MAC address. If we already know this address, we just copy it. If we
 253  * don't, we use the neighbour framework to find out. In both cases, we make
 254  * sure that br_handle_frame_finish() is called afterwards.
 255  */
 256 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
 257 {
 258         struct neighbour *neigh;
 259         struct dst_entry *dst;
 260
 261         skb->dev = bridge_parent(skb->dev);
 262         if (!skb->dev)
 263                 goto free_skb;
 264         dst = skb_dst(skb);
 265         neigh = dst_neigh_lookup_skb(dst, skb);
 266         if (neigh) {
 267                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 268                 int ret;
 269
 270                 if (neigh->hh.hh_len) {
 271                         neigh_hh_bridge(&neigh->hh, skb);
 272                         skb->dev = nf_bridge->physindev;
 273                         ret = br_handle_frame_finish(net, sk, skb);
 274                 } else {
 275                         /* the neighbour function below overwrites the complete
 276                          * MAC header, so we save the Ethernet source address and
 277                          * protocol number.
 278                          */
 279                         skb_copy_from_linear_data_offset(skb,
 280                                                          -(ETH_HLEN-ETH_ALEN),
 281                                                          nf_bridge->neigh_header,
 282                                                          ETH_HLEN-ETH_ALEN);
 283                         /* tell br_dev_xmit to continue with forwarding */
 284                         nf_bridge->bridged_dnat = 1;
 285                         /* FIXME Need to refragment */
 286                         ret = neigh->output(neigh, skb);
 287                 }
 288                 neigh_release(neigh);
 289                 return ret;
 290         }
 291 free_skb:
 292         kfree_skb(skb);
 293         return 0;
 294 }
 295
 296 static inline bool
 297 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
 298                              const struct nf_bridge_info *nf_bridge)
 299 {
 300         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
 301 }
 302
 303 /* This requires some explaining. If DNAT has taken place,
 304  * we will need to fix up the destination Ethernet address.
 305  * This is also true when SNAT takes place (for the reply direction).
 306  *
 307  * There are two cases to consider:
 308  * 1. The packet was DNAT'ed to a device in the same bridge
 309  *    port group as it was received on. We can still bridge
 310  *    the packet.
 311  * 2. The packet was DNAT'ed to a different device, either
 312  *    a non-bridged device or another bridge port group.
 313  *    The packet will need to be routed.
 314  *
 315  * The correct way of distinguishing between these two cases is to
 316  * call ip_route_input() and to look at skb->dst->dev, which is
 317  * changed to the destination device if ip_route_input() succeeds.
 318  *
 319  * Let's first consider the case that ip_route_input() succeeds:
 320  *
 321  * If the output device equals the logical bridge device the packet
 322  * came in on, we can consider this bridging. The corresponding MAC
 323  * address will be obtained in br_nf_pre_routing_finish_bridge.
 324  * Otherwise, the packet is considered to be routed and we just
 325  * change the destination MAC address so that the packet will
 326  * later be passed up to the IP stack to be routed. For a redirected
 327  * packet, ip_route_input() will give back the localhost as output device,
 328  * which differs from the bridge device.
 329  *
 330  * Let's now consider the case that ip_route_input() fails:
 331  *
 332  * This can be because the destination address is martian, in which case
 333  * the packet will be dropped.
 334  * If IP forwarding is disabled, ip_route_input() will fail, while
 335  * ip_route_output_key() can return success. The source
 336  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 337  * thinks we're handling a locally generated packet and won't care
 338  * if IP forwarding is enabled. If the output device equals the logical bridge
 339  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 340  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 341  */
 342 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 343 {
 344         struct net_device *dev = skb->dev;
 345         struct iphdr *iph = ip_hdr(skb);
 346         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 347         struct rtable *rt;
 348         int err;
 349
 350         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 351
 352         if (nf_bridge->pkt_otherhost) {
 353                 skb->pkt_type = PACKET_OTHERHOST;
 354                 nf_bridge->pkt_otherhost = false;
 355         }
 356         nf_bridge->in_prerouting = 0;
 357         if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
 358                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 359                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 360
 361                         /* If err equals -EHOSTUNREACH the error is due to a
 362                          * martian destination or due to the fact that
 363                          * forwarding is disabled. For most martian packets,
 364                          * ip_route_output_key() will fail. It won't fail for 2 types of
 365                          * martian destinations: loopback destinations and destination
 366                          * 0.0.0.0. In both cases the packet will be dropped because the
 367                          * destination is the loopback device and not the bridge. */
 368                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 369                                 goto free_skb;
 370
 371                         rt = ip_route_output(net, iph->daddr, 0,
 372                                              RT_TOS(iph->tos), 0);
 373                         if (!IS_ERR(rt)) {
 374                                 /* - Bridged-and-DNAT'ed traffic doesn't
 375                                  *   require ip_forwarding. */
 376                                 if (rt->dst.dev == dev) {
 377                                         skb_dst_set(skb, &rt->dst);
 378                                         goto bridged_dnat;
 379                                 }
 380                                 ip_rt_put(rt);
 381                         }
 382 free_skb:
 383                         kfree_skb(skb);
 384                         return 0;
 385                 } else {
 386                         if (skb_dst(skb)->dev == dev) {
 387 bridged_dnat:
 388                                 skb->dev = nf_bridge->physindev;
 389                                 nf_bridge_update_protocol(skb);
 390                                 nf_bridge_push_encap_header(skb);
 391                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 392                                                NF_BR_PRE_ROUTING,
 393                                                net, sk, skb, skb->dev, NULL,
 394                                                br_nf_pre_routing_finish_bridge,
 395                                                1);
 396                                 return 0;
 397                         }
 398                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
 399                         skb->pkt_type = PACKET_HOST;
 400                 }
 401         } else {
 402                 rt = bridge_parent_rtable(nf_bridge->physindev);
 403                 if (!rt) {
 404                         kfree_skb(skb);
 405                         return 0;
 406                 }
 407                 skb_dst_set_noref(skb, &rt->dst);
 408         }
 409
 410         skb->dev = nf_bridge->physindev;
 411         nf_bridge_update_protocol(skb);
 412         nf_bridge_push_encap_header(skb);
 413         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, net, sk, skb,
 414                        skb->dev, NULL,
 415                        br_handle_frame_finish, 1);
 416
 417         return 0;
 418 }
 419
 420 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
 421 {
 422         struct net_device *vlan, *br;
 423
 424         br = bridge_parent(dev);
 425         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
 426                 return br;
 427
 428         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
 429                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
 430
 431         return vlan ? vlan : br;
 432 }
 433
 434 /* Some common code for IPv4/IPv6 */
 435 struct net_device *setup_pre_routing(struct sk_buff *skb)
 436 {
 437         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 438
 439         if (skb->pkt_type == PACKET_OTHERHOST) {
 440                 skb->pkt_type = PACKET_HOST;
 441                 nf_bridge->pkt_otherhost = true;
 442         }
 443
 444         nf_bridge->in_prerouting = 1;
 445         nf_bridge->physindev = skb->dev;
 446         skb->dev = brnf_get_logical_dev(skb, skb->dev);
 447
 448         if (skb->protocol == htons(ETH_P_8021Q))
 449                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
 450         else if (skb->protocol == htons(ETH_P_PPP_SES))
 451                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
 452
 453         /* Must drop socket now because of tproxy. */
 454         skb_orphan(skb);
 455         return skb->dev;
 456 }
 457
 458 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 459  * Replicate the checks that IPv4 does on packet reception.
 460  * Set skb->dev to the bridge device (i.e. parent of the
 461  * receiving device) to make netfilter happy, the REDIRECT
 462  * target in particular.  Save the original destination IP
 463  * address to be able to detect DNAT afterwards. */
 464 static unsigned int br_nf_pre_routing(void *priv,
 465                                       struct sk_buff *skb,
 466                                       const struct nf_hook_state *state)
 467 {
 468         struct nf_bridge_info *nf_bridge;
 469         struct net_bridge_port *p;
 470         struct net_bridge *br;
 471         __u32 len = nf_bridge_encap_header_len(skb);
 472
 473         if (unlikely(!pskb_may_pull(skb, len)))
 474                 return NF_DROP;
 475
 476         p = br_port_get_rcu(state->in);
 477         if (p == NULL)
 478                 return NF_DROP;
 479         br = p->br;
 480
 481         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
 482                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 483                         return NF_ACCEPT;
 484
 485                 nf_bridge_pull_encap_header_rcsum(skb);
 486                 return br_nf_pre_routing_ipv6(priv, skb, state);
 487         }
 488
 489         if (!brnf_call_iptables && !br->nf_call_iptables)
 490                 return NF_ACCEPT;
 491
 492         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
 493                 return NF_ACCEPT;
 494
 495         nf_bridge_pull_encap_header_rcsum(skb);
 496
 497         if (br_validate_ipv4(state->net, skb))
 498                 return NF_DROP;
 499
 500         nf_bridge_put(skb->nf_bridge);
 501         if (!nf_bridge_alloc(skb))
 502                 return NF_DROP;
 503         if (!setup_pre_routing(skb))
 504                 return NF_DROP;
 505
 506         nf_bridge = nf_bridge_info_get(skb);
 507         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
 508
 509         skb->protocol = htons(ETH_P_IP);
 510
 511         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
 512                 skb->dev, NULL,
 513                 br_nf_pre_routing_finish);
 514
 515         return NF_STOLEN;
 516 }
 517
 518
 519 /* PF_BRIDGE/LOCAL_IN ************************************************/
 520 /* The packet is locally destined, which requires a real
 521  * dst_entry, so detach the fake one.  On the way up, the
 522  * packet would pass through PRE_ROUTING again (which already
 523  * took place when the packet entered the bridge), but we
 524  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 525  * prevent this from happening. */
 526 static unsigned int br_nf_local_in(void *priv,
 527                                    struct sk_buff *skb,
 528                                    const struct nf_hook_state *state)
 529 {
 530         br_drop_fake_rtable(skb);
 531         return NF_ACCEPT;
 532 }
 533
 534 /* PF_BRIDGE/FORWARD *************************************************/
 535 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 536 {
 537         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 538         struct net_device *in;
 539
 540         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
 541
 542                 if (skb->protocol == htons(ETH_P_IP))
 543                         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 544
 545                 if (skb->protocol == htons(ETH_P_IPV6))
 546                         nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 547
 548                 in = nf_bridge->physindev;
 549                 if (nf_bridge->pkt_otherhost) {
 550                         skb->pkt_type = PACKET_OTHERHOST;
 551                         nf_bridge->pkt_otherhost = false;
 552                 }
 553                 nf_bridge_update_protocol(skb);
 554         } else {
 555                 in = *((struct net_device **)(skb->cb));
 556         }
 557         nf_bridge_push_encap_header(skb);
 558
 559         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, net, sk, skb,
 560                        in, skb->dev, br_forward_finish, 1);
 561         return 0;
 562 }
 563
 564
 565 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 566  * netfilter with indev and outdev set to the bridge device,
 567  * but we are still able to filter on the 'real' indev/outdev
 568  * because of the physdev module. For ARP, indev and outdev are the
 569  * bridge ports. */
 570 static unsigned int br_nf_forward_ip(void *priv,
 571                                      struct sk_buff *skb,
 572                                      const struct nf_hook_state *state)
 573 {
 574         struct nf_bridge_info *nf_bridge;
 575         struct net_device *parent;
 576         u_int8_t pf;
 577
 578         if (!skb->nf_bridge)
 579                 return NF_ACCEPT;
 580
 581         /* Need exclusive nf_bridge_info since we might have multiple
 582          * different physoutdevs. */
 583         if (!nf_bridge_unshare(skb))
 584                 return NF_DROP;
 585
 586         nf_bridge = nf_bridge_info_get(skb);
 587         if (!nf_bridge)
 588                 return NF_DROP;
 589
 590         parent = bridge_parent(state->out);
 591         if (!parent)
 592                 return NF_DROP;
 593
 594         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 595                 pf = NFPROTO_IPV4;
 596         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 597                 pf = NFPROTO_IPV6;
 598         else
 599                 return NF_ACCEPT;
 600
 601         nf_bridge_pull_encap_header(skb);
 602
 603         if (skb->pkt_type == PACKET_OTHERHOST) {
 604                 skb->pkt_type = PACKET_HOST;
 605                 nf_bridge->pkt_otherhost = true;
 606         }
 607
 608         if (pf == NFPROTO_IPV4) {
 609                 if (br_validate_ipv4(state->net, skb))
 610                         return NF_DROP;
 611                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 612         }
 613
 614         if (pf == NFPROTO_IPV6) {
 615                 if (br_validate_ipv6(state->net, skb))
 616                         return NF_DROP;
 617                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 618         }
 619
 620         nf_bridge->physoutdev = skb->dev;
 621         if (pf == NFPROTO_IPV4)
 622                 skb->protocol = htons(ETH_P_IP);
 623         else
 624                 skb->protocol = htons(ETH_P_IPV6);
 625
 626         NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
 627                 brnf_get_logical_dev(skb, state->in),
 628                 parent, br_nf_forward_finish);
 629
 630         return NF_STOLEN;
 631 }
 632
 633 static unsigned int br_nf_forward_arp(void *priv,
 634                                       struct sk_buff *skb,
 635                                       const struct nf_hook_state *state)
 636 {
 637         struct net_bridge_port *p;
 638         struct net_bridge *br;
 639         struct net_device **d = (struct net_device **)(skb->cb);
 640
 641         p = br_port_get_rcu(state->out);
 642         if (p == NULL)
 643                 return NF_ACCEPT;
 644         br = p->br;
 645
 646         if (!brnf_call_arptables && !br->nf_call_arptables)
 647                 return NF_ACCEPT;
 648
 649         if (!IS_ARP(skb)) {
 650                 if (!IS_VLAN_ARP(skb))
 651                         return NF_ACCEPT;
 652                 nf_bridge_pull_encap_header(skb);
 653         }
 654
 655         if (arp_hdr(skb)->ar_pln != 4) {
 656                 if (IS_VLAN_ARP(skb))
 657                         nf_bridge_push_encap_header(skb);
 658                 return NF_ACCEPT;
 659         }
 660         *d = state->in;
 661         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
 662                 state->in, state->out, br_nf_forward_finish);
 663
 664         return NF_STOLEN;
 665 }
 666
 667 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 668 {
 669         struct brnf_frag_data *data;
 670         int err;
 671
 672         data = this_cpu_ptr(&brnf_frag_data_storage);
 673         err = skb_cow_head(skb, data->size);
 674
 675         if (err) {
 676                 kfree_skb(skb);
 677                 return 0;
 678         }
 679
 680         if (data->vlan_tci) {
 681                 skb->vlan_tci = data->vlan_tci;
 682                 skb->vlan_proto = data->vlan_proto;
 683         }
 684
 685         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
 686         __skb_push(skb, data->encap_size);
 687
 688         nf_bridge_info_free(skb);
 689         return br_dev_queue_push_xmit(net, sk, skb);
 690 }
 691
 692 static int
 693 br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 694                   int (*output)(struct net *, struct sock *, struct sk_buff *))
 695 {
 696         unsigned int mtu = ip_skb_dst_mtu(skb);
 697         struct iphdr *iph = ip_hdr(skb);
 698
 699         if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
 700                      (IPCB(skb)->frag_max_size &&
 701                       IPCB(skb)->frag_max_size > mtu))) {
 702                 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 703                 kfree_skb(skb);
 704                 return -EMSGSIZE;
 705         }
 706
 707         return ip_do_fragment(net, sk, skb, output);
 708 }
 709
 710 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
 711 {
 712         if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
 713                 return PPPOE_SES_HLEN;
 714         return 0;
 715 }
 716
 717 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 718 {
 719         struct nf_bridge_info *nf_bridge;
 720         unsigned int mtu_reserved;
 721
 722         mtu_reserved = nf_bridge_mtu_reduction(skb);
 723
 724         if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
 725                 nf_bridge_info_free(skb);
 726                 return br_dev_queue_push_xmit(net, sk, skb);
 727         }
 728
 729         nf_bridge = nf_bridge_info_get(skb);
 730
 731         /* This is wrong! We should preserve the original fragment
 732          * boundaries by preserving frag_list rather than refragmenting.
 733          */
 734         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
 735             skb->protocol == htons(ETH_P_IP)) {
 736                 struct brnf_frag_data *data;
 737
 738                 if (br_validate_ipv4(net, skb))
 739                         goto drop;
 740
 741                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 742
 743                 nf_bridge_update_protocol(skb);
 744
 745                 data = this_cpu_ptr(&brnf_frag_data_storage);
 746
 747                 data->vlan_tci = skb->vlan_tci;
 748                 data->vlan_proto = skb->vlan_proto;
 749                 data->encap_size = nf_bridge_encap_header_len(skb);
 750                 data->size = ETH_HLEN + data->encap_size;
 751
 752                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 753                                                  data->size);
 754
 755                 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
 756         }
 757         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
 758             skb->protocol == htons(ETH_P_IPV6)) {
 759                 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 760                 struct brnf_frag_data *data;
 761
 762                 if (br_validate_ipv6(net, skb))
 763                         goto drop;
 764
 765                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 766
 767                 nf_bridge_update_protocol(skb);
 768
 769                 data = this_cpu_ptr(&brnf_frag_data_storage);
 770                 data->encap_size = nf_bridge_encap_header_len(skb);
 771                 data->size = ETH_HLEN + data->encap_size;
 772
 773                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 774                                                  data->size);
 775
 776                 if (v6ops)
 777                         return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
 778
 779                 kfree_skb(skb);
 780                 return -EMSGSIZE;
 781         }
 782         nf_bridge_info_free(skb);
 783         return br_dev_queue_push_xmit(net, sk, skb);
 784  drop:
 785         kfree_skb(skb);
 786         return 0;
 787 }
 788
 789 /* PF_BRIDGE/POST_ROUTING ********************************************/
 790 static unsigned int br_nf_post_routing(void *priv,
 791                                        struct sk_buff *skb,
 792                                        const struct nf_hook_state *state)
 793 {
 794         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 795         struct net_device *realoutdev = bridge_parent(skb->dev);
 796         u_int8_t pf;
 797
 798         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
 799          * on a bridge, but was delivered locally and is now being routed:
 800          *
 801          * POST_ROUTING was already invoked from the ip stack.
 802          */
 803         if (!nf_bridge || !nf_bridge->physoutdev)
 804                 return NF_ACCEPT;
 805
 806         if (!realoutdev)
 807                 return NF_DROP;
 808
 809         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 810                 pf = NFPROTO_IPV4;
 811         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 812                 pf = NFPROTO_IPV6;
 813         else
 814                 return NF_ACCEPT;
 815
 816         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 817          * about the value of skb->pkt_type. */
 818         if (skb->pkt_type == PACKET_OTHERHOST) {
 819                 skb->pkt_type = PACKET_HOST;
 820                 nf_bridge->pkt_otherhost = true;
 821         }
 822
 823         nf_bridge_pull_encap_header(skb);
 824         if (pf == NFPROTO_IPV4)
 825                 skb->protocol = htons(ETH_P_IP);
 826         else
 827                 skb->protocol = htons(ETH_P_IPV6);
 828
 829         NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
 830                 NULL, realoutdev,
 831                 br_nf_dev_queue_xmit);
 832
 833         return NF_STOLEN;
 834 }
 835
 836 /* IP/SABOTAGE *****************************************************/
 837 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 838  * for the second time. */
 839 static unsigned int ip_sabotage_in(void *priv,
 840                                    struct sk_buff *skb,
 841                                    const struct nf_hook_state *state)
 842 {
 843         if (skb->nf_bridge && !skb->nf_bridge->in_prerouting)
 844                 return NF_STOP;
 845
 846         return NF_ACCEPT;
 847 }
 848
 849 /* This is called when br_netfilter has called into iptables/netfilter,
 850  * and DNAT has taken place on a bridge-forwarded packet.
 851  *
 852  * neigh->output has created a new MAC header, with local br0 MAC
 853  * as saddr.
 854  *
 855  * This restores the original MAC saddr of the bridged packet
 856  * before invoking bridge forward logic to transmit the packet.
 857  */
 858 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 859 {
 860         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 861
 862         skb_pull(skb, ETH_HLEN);
 863         nf_bridge->bridged_dnat = 0;
 864
 865         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
 866
 867         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
 868                                        nf_bridge->neigh_header,
 869                                        ETH_HLEN - ETH_ALEN);
 870         skb->dev = nf_bridge->physindev;
 871
 872         nf_bridge->physoutdev = NULL;
 873         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 874 }
 875
 876 static int br_nf_dev_xmit(struct sk_buff *skb)
 877 {
 878         if (skb->nf_bridge && skb->nf_bridge->bridged_dnat) {
 879                 br_nf_pre_routing_finish_bridge_slow(skb);
 880                 return 1;
 881         }
 882         return 0;
 883 }
 884
 885 static const struct nf_br_ops br_ops = {
 886         .br_dev_xmit_hook =     br_nf_dev_xmit,
 887 };
 888
 889 void br_netfilter_enable(void)
 890 {
 891 }
 892 EXPORT_SYMBOL_GPL(br_netfilter_enable);
 893
 894 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 895  * br_dev_queue_push_xmit is called afterwards */
 896 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 897         {
 898                 .hook = br_nf_pre_routing,
 899                 .pf = NFPROTO_BRIDGE,
 900                 .hooknum = NF_BR_PRE_ROUTING,
 901                 .priority = NF_BR_PRI_BRNF,
 902         },
 903         {
 904                 .hook = br_nf_local_in,
 905                 .pf = NFPROTO_BRIDGE,
 906                 .hooknum = NF_BR_LOCAL_IN,
 907                 .priority = NF_BR_PRI_BRNF,
 908         },
 909         {
 910                 .hook = br_nf_forward_ip,
 911                 .pf = NFPROTO_BRIDGE,
 912                 .hooknum = NF_BR_FORWARD,
 913                 .priority = NF_BR_PRI_BRNF - 1,
 914         },
 915         {
 916                 .hook = br_nf_forward_arp,
 917                 .pf = NFPROTO_BRIDGE,
 918                 .hooknum = NF_BR_FORWARD,
 919                 .priority = NF_BR_PRI_BRNF,
 920         },
 921         {
 922                 .hook = br_nf_post_routing,
 923                 .pf = NFPROTO_BRIDGE,
 924                 .hooknum = NF_BR_POST_ROUTING,
 925                 .priority = NF_BR_PRI_LAST,
 926         },
 927         {
 928                 .hook = ip_sabotage_in,
 929                 .pf = NFPROTO_IPV4,
 930                 .hooknum = NF_INET_PRE_ROUTING,
 931                 .priority = NF_IP_PRI_FIRST,
 932         },
 933         {
 934                 .hook = ip_sabotage_in,
 935                 .pf = NFPROTO_IPV6,
 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(struct 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 struct 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                 .procname       = "bridge-nf-pass-vlan-input-dev",
 993                 .data           = &brnf_pass_vlan_indev,
 994                 .maxlen         = sizeof(int),
 995                 .mode           = 0644,
 996                 .proc_handler   = brnf_sysctl_call_tables,
 997         },
 998         { }
 999 };
1000 #endif
1001
1002 static int __init br_netfilter_init(void)
1003 {
1004         int ret;
1005
1006         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1007         if (ret < 0)
1008                 return ret;
1009
1010 #ifdef CONFIG_SYSCTL
1011         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1012         if (brnf_sysctl_header == NULL) {
1013                 printk(KERN_WARNING
1014                        "br_netfilter: can't register to sysctl.\n");
1015                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1016                 return -ENOMEM;
1017         }
1018 #endif
1019         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1020         printk(KERN_NOTICE "Bridge firewalling registered\n");
1021         return 0;
1022 }
1023
1024 static void __exit br_netfilter_fini(void)
1025 {
1026         RCU_INIT_POINTER(nf_br_ops, NULL);
1027         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1028 #ifdef CONFIG_SYSCTL
1029         unregister_net_sysctl_table(brnf_sysctl_header);
1030 #endif
1031 }
1032
1033 module_init(br_netfilter_init);
1034 module_exit(br_netfilter_fini);
1035
1036 MODULE_LICENSE("GPL");
1037 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1038 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1039 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");