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 = 0;
  53 static int brnf_filter_pppoe_tagged __read_mostly = 0;
  54 static int brnf_pass_vlan_indev __read_mostly = 0;
  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 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) || IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 115 struct brnf_frag_data {
 116         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
 117         u8 encap_size;
 118         u8 size;
 119         u16 vlan_tci;
 120         __be16 vlan_proto;
 121 };
 122
 123 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
 124 #endif
 125
 126 static void nf_bridge_info_free(struct sk_buff *skb)
 127 {
 128         if (skb->nf_bridge) {
 129                 nf_bridge_put(skb->nf_bridge);
 130                 skb->nf_bridge = NULL;
 131         }
 132 }
 133
 134 static inline struct net_device *bridge_parent(const struct net_device *dev)
 135 {
 136         struct net_bridge_port *port;
 137
 138         port = br_port_get_rcu(dev);
 139         return port ? port->br->dev : NULL;
 140 }
 141
 142 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 143 {
 144         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 145
 146         if (atomic_read(&nf_bridge->use) > 1) {
 147                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 148
 149                 if (tmp) {
 150                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 151                         atomic_set(&tmp->use, 1);
 152                 }
 153                 nf_bridge_put(nf_bridge);
 154                 nf_bridge = tmp;
 155         }
 156         return nf_bridge;
 157 }
 158
 159 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
 160 {
 161         switch (skb->protocol) {
 162         case __cpu_to_be16(ETH_P_8021Q):
 163                 return VLAN_HLEN;
 164         case __cpu_to_be16(ETH_P_PPP_SES):
 165                 return PPPOE_SES_HLEN;
 166         default:
 167                 return 0;
 168         }
 169 }
 170
 171 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 172 {
 173         unsigned int len = nf_bridge_encap_header_len(skb);
 174
 175         skb_pull(skb, len);
 176         skb->network_header += len;
 177 }
 178
 179 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 180 {
 181         unsigned int len = nf_bridge_encap_header_len(skb);
 182
 183         skb_pull_rcsum(skb, len);
 184         skb->network_header += len;
 185 }
 186
 187 /* When handing a packet over to the IP layer
 188  * check whether we have a skb that is in the
 189  * expected format
 190  */
 191
 192 static int br_validate_ipv4(struct sk_buff *skb)
 193 {
 194         const struct iphdr *iph;
 195         struct net_device *dev = skb->dev;
 196         u32 len;
 197
 198         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 199                 goto inhdr_error;
 200
 201         iph = ip_hdr(skb);
 202
 203         /* Basic sanity checks */
 204         if (iph->ihl < 5 || iph->version != 4)
 205                 goto inhdr_error;
 206
 207         if (!pskb_may_pull(skb, iph->ihl*4))
 208                 goto inhdr_error;
 209
 210         iph = ip_hdr(skb);
 211         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 212                 goto inhdr_error;
 213
 214         len = ntohs(iph->tot_len);
 215         if (skb->len < len) {
 216                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 217                 goto drop;
 218         } else if (len < (iph->ihl*4))
 219                 goto inhdr_error;
 220
 221         if (pskb_trim_rcsum(skb, len)) {
 222                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 223                 goto drop;
 224         }
 225
 226         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 227         /* We should really parse IP options here but until
 228          * somebody who actually uses IP options complains to
 229          * us we'll just silently ignore the options because
 230          * we're lazy!
 231          */
 232         return 0;
 233
 234 inhdr_error:
 235         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 236 drop:
 237         return -1;
 238 }
 239
 240 void nf_bridge_update_protocol(struct sk_buff *skb)
 241 {
 242         switch (skb->nf_bridge->orig_proto) {
 243         case BRNF_PROTO_8021Q:
 244                 skb->protocol = htons(ETH_P_8021Q);
 245                 break;
 246         case BRNF_PROTO_PPPOE:
 247                 skb->protocol = htons(ETH_P_PPP_SES);
 248                 break;
 249         case BRNF_PROTO_UNCHANGED:
 250                 break;
 251         }
 252 }
 253
 254 /* Obtain the correct destination MAC address, while preserving the original
 255  * source MAC address. If we already know this address, we just copy it. If we
 256  * don't, we use the neighbour framework to find out. In both cases, we make
 257  * sure that br_handle_frame_finish() is called afterwards.
 258  */
 259 int br_nf_pre_routing_finish_bridge(struct sock *sk, struct sk_buff *skb)
 260 {
 261         struct neighbour *neigh;
 262         struct dst_entry *dst;
 263
 264         skb->dev = bridge_parent(skb->dev);
 265         if (!skb->dev)
 266                 goto free_skb;
 267         dst = skb_dst(skb);
 268         neigh = dst_neigh_lookup_skb(dst, skb);
 269         if (neigh) {
 270                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 271                 int ret;
 272
 273                 if (neigh->hh.hh_len) {
 274                         neigh_hh_bridge(&neigh->hh, skb);
 275                         skb->dev = nf_bridge->physindev;
 276                         ret = br_handle_frame_finish(sk, skb);
 277                 } else {
 278                         /* the neighbour function below overwrites the complete
 279                          * MAC header, so we save the Ethernet source address and
 280                          * protocol number.
 281                          */
 282                         skb_copy_from_linear_data_offset(skb,
 283                                                          -(ETH_HLEN-ETH_ALEN),
 284                                                          nf_bridge->neigh_header,
 285                                                          ETH_HLEN-ETH_ALEN);
 286                         /* tell br_dev_xmit to continue with forwarding */
 287                         nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 288                         /* FIXME Need to refragment */
 289                         ret = neigh->output(neigh, skb);
 290                 }
 291                 neigh_release(neigh);
 292                 return ret;
 293         }
 294 free_skb:
 295         kfree_skb(skb);
 296         return 0;
 297 }
 298
 299 static inline bool
 300 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
 301                              const struct nf_bridge_info *nf_bridge)
 302 {
 303         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
 304 }
 305
 306 /* This requires some explaining. If DNAT has taken place,
 307  * we will need to fix up the destination Ethernet address.
 308  * This is also true when SNAT takes place (for the reply direction).
 309  *
 310  * There are two cases to consider:
 311  * 1. The packet was DNAT'ed to a device in the same bridge
 312  *    port group as it was received on. We can still bridge
 313  *    the packet.
 314  * 2. The packet was DNAT'ed to a different device, either
 315  *    a non-bridged device or another bridge port group.
 316  *    The packet will need to be routed.
 317  *
 318  * The correct way of distinguishing between these two cases is to
 319  * call ip_route_input() and to look at skb->dst->dev, which is
 320  * changed to the destination device if ip_route_input() succeeds.
 321  *
 322  * Let's first consider the case that ip_route_input() succeeds:
 323  *
 324  * If the output device equals the logical bridge device the packet
 325  * came in on, we can consider this bridging. The corresponding MAC
 326  * address will be obtained in br_nf_pre_routing_finish_bridge.
 327  * Otherwise, the packet is considered to be routed and we just
 328  * change the destination MAC address so that the packet will
 329  * later be passed up to the IP stack to be routed. For a redirected
 330  * packet, ip_route_input() will give back the localhost as output device,
 331  * which differs from the bridge device.
 332  *
 333  * Let's now consider the case that ip_route_input() fails:
 334  *
 335  * This can be because the destination address is martian, in which case
 336  * the packet will be dropped.
 337  * If IP forwarding is disabled, ip_route_input() will fail, while
 338  * ip_route_output_key() can return success. The source
 339  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 340  * thinks we're handling a locally generated packet and won't care
 341  * if IP forwarding is enabled. If the output device equals the logical bridge
 342  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 343  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 344  */
 345 static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb)
 346 {
 347         struct net_device *dev = skb->dev;
 348         struct iphdr *iph = ip_hdr(skb);
 349         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 350         struct rtable *rt;
 351         int err;
 352
 353         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 354
 355         if (nf_bridge->pkt_otherhost) {
 356                 skb->pkt_type = PACKET_OTHERHOST;
 357                 nf_bridge->pkt_otherhost = false;
 358         }
 359         nf_bridge->mask &= ~BRNF_NF_BRIDGE_PREROUTING;
 360         if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
 361                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 362                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 363
 364                         /* If err equals -EHOSTUNREACH the error is due to a
 365                          * martian destination or due to the fact that
 366                          * forwarding is disabled. For most martian packets,
 367                          * ip_route_output_key() will fail. It won't fail for 2 types of
 368                          * martian destinations: loopback destinations and destination
 369                          * 0.0.0.0. In both cases the packet will be dropped because the
 370                          * destination is the loopback device and not the bridge. */
 371                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 372                                 goto free_skb;
 373
 374                         rt = ip_route_output(dev_net(dev), iph->daddr, 0,
 375                                              RT_TOS(iph->tos), 0);
 376                         if (!IS_ERR(rt)) {
 377                                 /* - Bridged-and-DNAT'ed traffic doesn't
 378                                  *   require ip_forwarding. */
 379                                 if (rt->dst.dev == dev) {
 380                                         skb_dst_set(skb, &rt->dst);
 381                                         goto bridged_dnat;
 382                                 }
 383                                 ip_rt_put(rt);
 384                         }
 385 free_skb:
 386                         kfree_skb(skb);
 387                         return 0;
 388                 } else {
 389                         if (skb_dst(skb)->dev == dev) {
 390 bridged_dnat:
 391                                 skb->dev = nf_bridge->physindev;
 392                                 nf_bridge_update_protocol(skb);
 393                                 nf_bridge_push_encap_header(skb);
 394                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
 395                                                NF_BR_PRE_ROUTING,
 396                                                sk, skb, skb->dev, NULL,
 397                                                br_nf_pre_routing_finish_bridge,
 398                                                1);
 399                                 return 0;
 400                         }
 401                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
 402                         skb->pkt_type = PACKET_HOST;
 403                 }
 404         } else {
 405                 rt = bridge_parent_rtable(nf_bridge->physindev);
 406                 if (!rt) {
 407                         kfree_skb(skb);
 408                         return 0;
 409                 }
 410                 skb_dst_set_noref(skb, &rt->dst);
 411         }
 412
 413         skb->dev = nf_bridge->physindev;
 414         nf_bridge_update_protocol(skb);
 415         nf_bridge_push_encap_header(skb);
 416         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
 417                        skb->dev, NULL,
 418                        br_handle_frame_finish, 1);
 419
 420         return 0;
 421 }
 422
 423 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
 424 {
 425         struct net_device *vlan, *br;
 426
 427         br = bridge_parent(dev);
 428         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
 429                 return br;
 430
 431         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
 432                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
 433
 434         return vlan ? vlan : br;
 435 }
 436
 437 /* Some common code for IPv4/IPv6 */
 438 struct net_device *setup_pre_routing(struct sk_buff *skb)
 439 {
 440         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 441
 442         if (skb->pkt_type == PACKET_OTHERHOST) {
 443                 skb->pkt_type = PACKET_HOST;
 444                 nf_bridge->pkt_otherhost = true;
 445         }
 446
 447         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 448         nf_bridge->physindev = skb->dev;
 449         skb->dev = brnf_get_logical_dev(skb, skb->dev);
 450
 451         if (skb->protocol == htons(ETH_P_8021Q))
 452                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
 453         else if (skb->protocol == htons(ETH_P_PPP_SES))
 454                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
 455
 456         /* Must drop socket now because of tproxy. */
 457         skb_orphan(skb);
 458         return skb->dev;
 459 }
 460
 461 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 462  * Replicate the checks that IPv4 does on packet reception.
 463  * Set skb->dev to the bridge device (i.e. parent of the
 464  * receiving device) to make netfilter happy, the REDIRECT
 465  * target in particular.  Save the original destination IP
 466  * address to be able to detect DNAT afterwards. */
 467 static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
 468                                       struct sk_buff *skb,
 469                                       const struct nf_hook_state *state)
 470 {
 471         struct nf_bridge_info *nf_bridge;
 472         struct net_bridge_port *p;
 473         struct net_bridge *br;
 474         __u32 len = nf_bridge_encap_header_len(skb);
 475
 476         if (unlikely(!pskb_may_pull(skb, len)))
 477                 return NF_DROP;
 478
 479         p = br_port_get_rcu(state->in);
 480         if (p == NULL)
 481                 return NF_DROP;
 482         br = p->br;
 483
 484         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
 485                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 486                         return NF_ACCEPT;
 487
 488                 nf_bridge_pull_encap_header_rcsum(skb);
 489                 return br_nf_pre_routing_ipv6(ops, skb, state);
 490         }
 491
 492         if (!brnf_call_iptables && !br->nf_call_iptables)
 493                 return NF_ACCEPT;
 494
 495         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
 496                 return NF_ACCEPT;
 497
 498         nf_bridge_pull_encap_header_rcsum(skb);
 499
 500         if (br_validate_ipv4(skb))
 501                 return NF_DROP;
 502
 503         nf_bridge_put(skb->nf_bridge);
 504         if (!nf_bridge_alloc(skb))
 505                 return NF_DROP;
 506         if (!setup_pre_routing(skb))
 507                 return NF_DROP;
 508
 509         nf_bridge = nf_bridge_info_get(skb);
 510         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
 511
 512         skb->protocol = htons(ETH_P_IP);
 513
 514         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,
 515                 skb->dev, NULL,
 516                 br_nf_pre_routing_finish);
 517
 518         return NF_STOLEN;
 519 }
 520
 521
 522 /* PF_BRIDGE/LOCAL_IN ************************************************/
 523 /* The packet is locally destined, which requires a real
 524  * dst_entry, so detach the fake one.  On the way up, the
 525  * packet would pass through PRE_ROUTING again (which already
 526  * took place when the packet entered the bridge), but we
 527  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 528  * prevent this from happening. */
 529 static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
 530                                    struct sk_buff *skb,
 531                                    const struct nf_hook_state *state)
 532 {
 533         br_drop_fake_rtable(skb);
 534         return NF_ACCEPT;
 535 }
 536
 537 /* PF_BRIDGE/FORWARD *************************************************/
 538 static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
 539 {
 540         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 541         struct net_device *in;
 542
 543         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
 544
 545                 if (skb->protocol == htons(ETH_P_IP))
 546                         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 547
 548                 if (skb->protocol == htons(ETH_P_IPV6))
 549                         nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 550
 551                 in = nf_bridge->physindev;
 552                 if (nf_bridge->pkt_otherhost) {
 553                         skb->pkt_type = PACKET_OTHERHOST;
 554                         nf_bridge->pkt_otherhost = false;
 555                 }
 556                 nf_bridge_update_protocol(skb);
 557         } else {
 558                 in = *((struct net_device **)(skb->cb));
 559         }
 560         nf_bridge_push_encap_header(skb);
 561
 562         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, sk, skb,
 563                        in, skb->dev, br_forward_finish, 1);
 564         return 0;
 565 }
 566
 567
 568 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 569  * netfilter with indev and outdev set to the bridge device,
 570  * but we are still able to filter on the 'real' indev/outdev
 571  * because of the physdev module. For ARP, indev and outdev are the
 572  * bridge ports. */
 573 static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
 574                                      struct sk_buff *skb,
 575                                      const struct nf_hook_state *state)
 576 {
 577         struct nf_bridge_info *nf_bridge;
 578         struct net_device *parent;
 579         u_int8_t pf;
 580
 581         if (!skb->nf_bridge)
 582                 return NF_ACCEPT;
 583
 584         /* Need exclusive nf_bridge_info since we might have multiple
 585          * different physoutdevs. */
 586         if (!nf_bridge_unshare(skb))
 587                 return NF_DROP;
 588
 589         nf_bridge = nf_bridge_info_get(skb);
 590         if (!nf_bridge)
 591                 return NF_DROP;
 592
 593         parent = bridge_parent(state->out);
 594         if (!parent)
 595                 return NF_DROP;
 596
 597         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 598                 pf = NFPROTO_IPV4;
 599         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 600                 pf = NFPROTO_IPV6;
 601         else
 602                 return NF_ACCEPT;
 603
 604         nf_bridge_pull_encap_header(skb);
 605
 606         if (skb->pkt_type == PACKET_OTHERHOST) {
 607                 skb->pkt_type = PACKET_HOST;
 608                 nf_bridge->pkt_otherhost = true;
 609         }
 610
 611         if (pf == NFPROTO_IPV4) {
 612                 if (br_validate_ipv4(skb))
 613                         return NF_DROP;
 614                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 615         }
 616
 617         if (pf == NFPROTO_IPV6) {
 618                 if (br_validate_ipv6(skb))
 619                         return NF_DROP;
 620                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 621         }
 622
 623         nf_bridge->physoutdev = skb->dev;
 624         if (pf == NFPROTO_IPV4)
 625                 skb->protocol = htons(ETH_P_IP);
 626         else
 627                 skb->protocol = htons(ETH_P_IPV6);
 628
 629         NF_HOOK(pf, NF_INET_FORWARD, NULL, skb,
 630                 brnf_get_logical_dev(skb, state->in),
 631                 parent, br_nf_forward_finish);
 632
 633         return NF_STOLEN;
 634 }
 635
 636 static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
 637                                       struct sk_buff *skb,
 638                                       const struct nf_hook_state *state)
 639 {
 640         struct net_bridge_port *p;
 641         struct net_bridge *br;
 642         struct net_device **d = (struct net_device **)(skb->cb);
 643
 644         p = br_port_get_rcu(state->out);
 645         if (p == NULL)
 646                 return NF_ACCEPT;
 647         br = p->br;
 648
 649         if (!brnf_call_arptables && !br->nf_call_arptables)
 650                 return NF_ACCEPT;
 651
 652         if (!IS_ARP(skb)) {
 653                 if (!IS_VLAN_ARP(skb))
 654                         return NF_ACCEPT;
 655                 nf_bridge_pull_encap_header(skb);
 656         }
 657
 658         if (arp_hdr(skb)->ar_pln != 4) {
 659                 if (IS_VLAN_ARP(skb))
 660                         nf_bridge_push_encap_header(skb);
 661                 return NF_ACCEPT;
 662         }
 663         *d = state->in;
 664         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->sk, skb,
 665                 state->in, state->out, br_nf_forward_finish);
 666
 667         return NF_STOLEN;
 668 }
 669
 670 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) || IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 671 static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb)
 672 {
 673         struct brnf_frag_data *data;
 674         int err;
 675
 676         data = this_cpu_ptr(&brnf_frag_data_storage);
 677         err = skb_cow_head(skb, data->size);
 678
 679         if (err) {
 680                 kfree_skb(skb);
 681                 return 0;
 682         }
 683
 684         if (data->vlan_tci) {
 685                 skb->vlan_tci = data->vlan_tci;
 686                 skb->vlan_proto = data->vlan_proto;
 687         }
 688
 689         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
 690         __skb_push(skb, data->encap_size);
 691
 692         nf_bridge_info_free(skb);
 693         return br_dev_queue_push_xmit(sk, skb);
 694 }
 695 #endif
 696
 697 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 698 static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb,
 699                              int (*output)(struct sock *, struct sk_buff *))
 700 {
 701         unsigned int mtu = ip_skb_dst_mtu(skb);
 702         struct iphdr *iph = ip_hdr(skb);
 703         struct rtable *rt = skb_rtable(skb);
 704         struct net_device *dev = rt->dst.dev;
 705
 706         if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
 707                      (IPCB(skb)->frag_max_size &&
 708                       IPCB(skb)->frag_max_size > mtu))) {
 709                 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
 710                 kfree_skb(skb);
 711                 return -EMSGSIZE;
 712         }
 713
 714         return ip_do_fragment(sk, skb, output);
 715 }
 716 #endif
 717
 718 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
 719 {
 720         if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
 721                 return PPPOE_SES_HLEN;
 722         return 0;
 723 }
 724
 725 static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
 726 {
 727         struct nf_bridge_info *nf_bridge;
 728         unsigned int mtu_reserved;
 729
 730         mtu_reserved = nf_bridge_mtu_reduction(skb);
 731
 732         if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
 733                 nf_bridge_info_free(skb);
 734                 return br_dev_queue_push_xmit(sk, skb);
 735         }
 736
 737         nf_bridge = nf_bridge_info_get(skb);
 738
 739 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 740         /* This is wrong! We should preserve the original fragment
 741          * boundaries by preserving frag_list rather than refragmenting.
 742          */
 743         if (skb->protocol == htons(ETH_P_IP)) {
 744                 struct brnf_frag_data *data;
 745
 746                 if (br_validate_ipv4(skb))
 747                         goto drop;
 748
 749                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 750
 751                 nf_bridge_update_protocol(skb);
 752
 753                 data = this_cpu_ptr(&brnf_frag_data_storage);
 754
 755                 data->vlan_tci = skb->vlan_tci;
 756                 data->vlan_proto = skb->vlan_proto;
 757                 data->encap_size = nf_bridge_encap_header_len(skb);
 758                 data->size = ETH_HLEN + data->encap_size;
 759
 760                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 761                                                  data->size);
 762
 763                 return br_nf_ip_fragment(sk, skb, br_nf_push_frag_xmit);
 764         }
 765 #endif
 766 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 767         if (skb->protocol == htons(ETH_P_IPV6)) {
 768                 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 769                 struct brnf_frag_data *data;
 770
 771                 if (br_validate_ipv6(skb))
 772                         goto drop;
 773
 774                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 775
 776                 nf_bridge_update_protocol(skb);
 777
 778                 data = this_cpu_ptr(&brnf_frag_data_storage);
 779                 data->encap_size = nf_bridge_encap_header_len(skb);
 780                 data->size = ETH_HLEN + data->encap_size;
 781
 782                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 783                                                  data->size);
 784
 785                 if (v6ops)
 786                         return v6ops->fragment(sk, skb, br_nf_push_frag_xmit);
 787
 788                 kfree_skb(skb);
 789                 return -EMSGSIZE;
 790         }
 791 #endif
 792         nf_bridge_info_free(skb);
 793         return br_dev_queue_push_xmit(sk, skb);
 794  drop:
 795         kfree_skb(skb);
 796         return 0;
 797 }
 798
 799 /* PF_BRIDGE/POST_ROUTING ********************************************/
 800 static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
 801                                        struct sk_buff *skb,
 802                                        const struct nf_hook_state *state)
 803 {
 804         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 805         struct net_device *realoutdev = bridge_parent(skb->dev);
 806         u_int8_t pf;
 807
 808         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
 809          * on a bridge, but was delivered locally and is now being routed:
 810          *
 811          * POST_ROUTING was already invoked from the ip stack.
 812          */
 813         if (!nf_bridge || !nf_bridge->physoutdev)
 814                 return NF_ACCEPT;
 815
 816         if (!realoutdev)
 817                 return NF_DROP;
 818
 819         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 820                 pf = NFPROTO_IPV4;
 821         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 822                 pf = NFPROTO_IPV6;
 823         else
 824                 return NF_ACCEPT;
 825
 826         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 827          * about the value of skb->pkt_type. */
 828         if (skb->pkt_type == PACKET_OTHERHOST) {
 829                 skb->pkt_type = PACKET_HOST;
 830                 nf_bridge->pkt_otherhost = true;
 831         }
 832
 833         nf_bridge_pull_encap_header(skb);
 834         if (pf == NFPROTO_IPV4)
 835                 skb->protocol = htons(ETH_P_IP);
 836         else
 837                 skb->protocol = htons(ETH_P_IPV6);
 838
 839         NF_HOOK(pf, NF_INET_POST_ROUTING, state->sk, skb,
 840                 NULL, realoutdev,
 841                 br_nf_dev_queue_xmit);
 842
 843         return NF_STOLEN;
 844 }
 845
 846 /* IP/SABOTAGE *****************************************************/
 847 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 848  * for the second time. */
 849 static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
 850                                    struct sk_buff *skb,
 851                                    const struct nf_hook_state *state)
 852 {
 853         if (skb->nf_bridge &&
 854             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 855                 return NF_STOP;
 856         }
 857
 858         return NF_ACCEPT;
 859 }
 860
 861 /* This is called when br_netfilter has called into iptables/netfilter,
 862  * and DNAT has taken place on a bridge-forwarded packet.
 863  *
 864  * neigh->output has created a new MAC header, with local br0 MAC
 865  * as saddr.
 866  *
 867  * This restores the original MAC saddr of the bridged packet
 868  * before invoking bridge forward logic to transmit the packet.
 869  */
 870 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 871 {
 872         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 873
 874         skb_pull(skb, ETH_HLEN);
 875         nf_bridge->mask &= ~BRNF_BRIDGED_DNAT;
 876
 877         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
 878
 879         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
 880                                        nf_bridge->neigh_header,
 881                                        ETH_HLEN - ETH_ALEN);
 882         skb->dev = nf_bridge->physindev;
 883
 884         nf_bridge->physoutdev = NULL;
 885         br_handle_frame_finish(NULL, skb);
 886 }
 887
 888 static int br_nf_dev_xmit(struct sk_buff *skb)
 889 {
 890         if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
 891                 br_nf_pre_routing_finish_bridge_slow(skb);
 892                 return 1;
 893         }
 894         return 0;
 895 }
 896
 897 static const struct nf_br_ops br_ops = {
 898         .br_dev_xmit_hook =     br_nf_dev_xmit,
 899 };
 900
 901 void br_netfilter_enable(void)
 902 {
 903 }
 904 EXPORT_SYMBOL_GPL(br_netfilter_enable);
 905
 906 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 907  * br_dev_queue_push_xmit is called afterwards */
 908 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 909         {
 910                 .hook = br_nf_pre_routing,
 911                 .owner = THIS_MODULE,
 912                 .pf = NFPROTO_BRIDGE,
 913                 .hooknum = NF_BR_PRE_ROUTING,
 914                 .priority = NF_BR_PRI_BRNF,
 915         },
 916         {
 917                 .hook = br_nf_local_in,
 918                 .owner = THIS_MODULE,
 919                 .pf = NFPROTO_BRIDGE,
 920                 .hooknum = NF_BR_LOCAL_IN,
 921                 .priority = NF_BR_PRI_BRNF,
 922         },
 923         {
 924                 .hook = br_nf_forward_ip,
 925                 .owner = THIS_MODULE,
 926                 .pf = NFPROTO_BRIDGE,
 927                 .hooknum = NF_BR_FORWARD,
 928                 .priority = NF_BR_PRI_BRNF - 1,
 929         },
 930         {
 931                 .hook = br_nf_forward_arp,
 932                 .owner = THIS_MODULE,
 933                 .pf = NFPROTO_BRIDGE,
 934                 .hooknum = NF_BR_FORWARD,
 935                 .priority = NF_BR_PRI_BRNF,
 936         },
 937         {
 938                 .hook = br_nf_post_routing,
 939                 .owner = THIS_MODULE,
 940                 .pf = NFPROTO_BRIDGE,
 941                 .hooknum = NF_BR_POST_ROUTING,
 942                 .priority = NF_BR_PRI_LAST,
 943         },
 944         {
 945                 .hook = ip_sabotage_in,
 946                 .owner = THIS_MODULE,
 947                 .pf = NFPROTO_IPV4,
 948                 .hooknum = NF_INET_PRE_ROUTING,
 949                 .priority = NF_IP_PRI_FIRST,
 950         },
 951         {
 952                 .hook = ip_sabotage_in,
 953                 .owner = THIS_MODULE,
 954                 .pf = NFPROTO_IPV6,
 955                 .hooknum = NF_INET_PRE_ROUTING,
 956                 .priority = NF_IP6_PRI_FIRST,
 957         },
 958 };
 959
 960 #ifdef CONFIG_SYSCTL
 961 static
 962 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
 963                             void __user *buffer, size_t *lenp, loff_t *ppos)
 964 {
 965         int ret;
 966
 967         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 968
 969         if (write && *(int *)(ctl->data))
 970                 *(int *)(ctl->data) = 1;
 971         return ret;
 972 }
 973
 974 static struct ctl_table brnf_table[] = {
 975         {
 976                 .procname       = "bridge-nf-call-arptables",
 977                 .data           = &brnf_call_arptables,
 978                 .maxlen         = sizeof(int),
 979                 .mode           = 0644,
 980                 .proc_handler   = brnf_sysctl_call_tables,
 981         },
 982         {
 983                 .procname       = "bridge-nf-call-iptables",
 984                 .data           = &brnf_call_iptables,
 985                 .maxlen         = sizeof(int),
 986                 .mode           = 0644,
 987                 .proc_handler   = brnf_sysctl_call_tables,
 988         },
 989         {
 990                 .procname       = "bridge-nf-call-ip6tables",
 991                 .data           = &brnf_call_ip6tables,
 992                 .maxlen         = sizeof(int),
 993                 .mode           = 0644,
 994                 .proc_handler   = brnf_sysctl_call_tables,
 995         },
 996         {
 997                 .procname       = "bridge-nf-filter-vlan-tagged",
 998                 .data           = &brnf_filter_vlan_tagged,
 999                 .maxlen         = sizeof(int),
1000                 .mode           = 0644,
1001                 .proc_handler   = brnf_sysctl_call_tables,
1002         },
1003         {
1004                 .procname       = "bridge-nf-filter-pppoe-tagged",
1005                 .data           = &brnf_filter_pppoe_tagged,
1006                 .maxlen         = sizeof(int),
1007                 .mode           = 0644,
1008                 .proc_handler   = brnf_sysctl_call_tables,
1009         },
1010         {
1011                 .procname       = "bridge-nf-pass-vlan-input-dev",
1012                 .data           = &brnf_pass_vlan_indev,
1013                 .maxlen         = sizeof(int),
1014                 .mode           = 0644,
1015                 .proc_handler   = brnf_sysctl_call_tables,
1016         },
1017         { }
1018 };
1019 #endif
1020
1021 static int __init br_netfilter_init(void)
1022 {
1023         int ret;
1024
1025         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1026         if (ret < 0)
1027                 return ret;
1028
1029 #ifdef CONFIG_SYSCTL
1030         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1031         if (brnf_sysctl_header == NULL) {
1032                 printk(KERN_WARNING
1033                        "br_netfilter: can't register to sysctl.\n");
1034                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1035                 return -ENOMEM;
1036         }
1037 #endif
1038         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1039         printk(KERN_NOTICE "Bridge firewalling registered\n");
1040         return 0;
1041 }
1042
1043 static void __exit br_netfilter_fini(void)
1044 {
1045         RCU_INIT_POINTER(nf_br_ops, NULL);
1046         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1047 #ifdef CONFIG_SYSCTL
1048         unregister_net_sysctl_table(brnf_sysctl_header);
1049 #endif
1050 }
1051
1052 module_init(br_netfilter_init);
1053 module_exit(br_netfilter_fini);
1054
1055 MODULE_LICENSE("GPL");
1056 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1057 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1058 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");