net/bridge/br_netfilter_hooks.c

   1 /*
   2  *      Handle firewalling
   3  *      Linux ethernet bridge
   4  *
   5  *      Authors:
   6  *      Lennert Buytenhek               <[email protected]>
   7  *      Bart De Schuymer                <[email protected]>
   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/rculist.h>
  34 #include <linux/inetdevice.h>
  35
  36 #include <net/ip.h>
  37 #include <net/ipv6.h>
  38 #include <net/addrconf.h>
  39 #include <net/route.h>
  40 #include <net/netfilter/br_netfilter.h>
  41 #include <net/netns/generic.h>
  42
  43 #include <linux/uaccess.h>
  44 #include "br_private.h"
  45 #ifdef CONFIG_SYSCTL
  46 #include <linux/sysctl.h>
  47 #endif
  48
  49 static unsigned int brnf_net_id __read_mostly;
  50
  51 struct brnf_net {
  52         bool enabled;
  53 };
  54
  55 #ifdef CONFIG_SYSCTL
  56 static struct ctl_table_header *brnf_sysctl_header;
  57 static int brnf_call_iptables __read_mostly = 1;
  58 static int brnf_call_ip6tables __read_mostly = 1;
  59 static int brnf_call_arptables __read_mostly = 1;
  60 static int brnf_filter_vlan_tagged __read_mostly;
  61 static int brnf_filter_pppoe_tagged __read_mostly;
  62 static int brnf_pass_vlan_indev __read_mostly;
  63 #else
  64 #define brnf_call_iptables 1
  65 #define brnf_call_ip6tables 1
  66 #define brnf_call_arptables 1
  67 #define brnf_filter_vlan_tagged 0
  68 #define brnf_filter_pppoe_tagged 0
  69 #define brnf_pass_vlan_indev 0
  70 #endif
  71
  72 #define IS_IP(skb) \
  73         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
  74
  75 #define IS_IPV6(skb) \
  76         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
  77
  78 #define IS_ARP(skb) \
  79         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
  80
  81 static inline __be16 vlan_proto(const struct sk_buff *skb)
  82 {
  83         if (skb_vlan_tag_present(skb))
  84                 return skb->protocol;
  85         else if (skb->protocol == htons(ETH_P_8021Q))
  86                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  87         else
  88                 return 0;
  89 }
  90
  91 #define IS_VLAN_IP(skb) \
  92         (vlan_proto(skb) == htons(ETH_P_IP) && \
  93          brnf_filter_vlan_tagged)
  94
  95 #define IS_VLAN_IPV6(skb) \
  96         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  97          brnf_filter_vlan_tagged)
  98
  99 #define IS_VLAN_ARP(skb) \
 100         (vlan_proto(skb) == htons(ETH_P_ARP) && \
 101          brnf_filter_vlan_tagged)
 102
 103 static inline __be16 pppoe_proto(const struct sk_buff *skb)
 104 {
 105         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
 106                             sizeof(struct pppoe_hdr)));
 107 }
 108
 109 #define IS_PPPOE_IP(skb) \
 110         (skb->protocol == htons(ETH_P_PPP_SES) && \
 111          pppoe_proto(skb) == htons(PPP_IP) && \
 112          brnf_filter_pppoe_tagged)
 113
 114 #define IS_PPPOE_IPV6(skb) \
 115         (skb->protocol == htons(ETH_P_PPP_SES) && \
 116          pppoe_proto(skb) == htons(PPP_IPV6) && \
 117          brnf_filter_pppoe_tagged)
 118
 119 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
 120 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
 121
 122 struct brnf_frag_data {
 123         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
 124         u8 encap_size;
 125         u8 size;
 126         u16 vlan_tci;
 127         __be16 vlan_proto;
 128 };
 129
 130 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
 131
 132 static void nf_bridge_info_free(struct sk_buff *skb)
 133 {
 134         if (skb->nf_bridge) {
 135                 nf_bridge_put(skb->nf_bridge);
 136                 skb->nf_bridge = NULL;
 137         }
 138 }
 139
 140 static inline struct net_device *bridge_parent(const struct net_device *dev)
 141 {
 142         struct net_bridge_port *port;
 143
 144         port = br_port_get_rcu(dev);
 145         return port ? port->br->dev : NULL;
 146 }
 147
 148 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 149 {
 150         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 151
 152         if (atomic_read(&nf_bridge->use) > 1) {
 153                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 154
 155                 if (tmp) {
 156                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 157                         atomic_set(&tmp->use, 1);
 158                 }
 159                 nf_bridge_put(nf_bridge);
 160                 nf_bridge = tmp;
 161         }
 162         return nf_bridge;
 163 }
 164
 165 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
 166 {
 167         switch (skb->protocol) {
 168         case __cpu_to_be16(ETH_P_8021Q):
 169                 return VLAN_HLEN;
 170         case __cpu_to_be16(ETH_P_PPP_SES):
 171                 return PPPOE_SES_HLEN;
 172         default:
 173                 return 0;
 174         }
 175 }
 176
 177 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 178 {
 179         unsigned int len = nf_bridge_encap_header_len(skb);
 180
 181         skb_pull(skb, len);
 182         skb->network_header += len;
 183 }
 184
 185 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 186 {
 187         unsigned int len = nf_bridge_encap_header_len(skb);
 188
 189         skb_pull_rcsum(skb, len);
 190         skb->network_header += len;
 191 }
 192
 193 /* When handing a packet over to the IP layer
 194  * check whether we have a skb that is in the
 195  * expected format
 196  */
 197
 198 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
 199 {
 200         const struct iphdr *iph;
 201         u32 len;
 202
 203         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 204                 goto inhdr_error;
 205
 206         iph = ip_hdr(skb);
 207
 208         /* Basic sanity checks */
 209         if (iph->ihl < 5 || iph->version != 4)
 210                 goto inhdr_error;
 211
 212         if (!pskb_may_pull(skb, iph->ihl*4))
 213                 goto inhdr_error;
 214
 215         iph = ip_hdr(skb);
 216         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 217                 goto inhdr_error;
 218
 219         len = ntohs(iph->tot_len);
 220         if (skb->len < len) {
 221                 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
 222                 goto drop;
 223         } else if (len < (iph->ihl*4))
 224                 goto inhdr_error;
 225
 226         if (pskb_trim_rcsum(skb, len)) {
 227                 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
 228                 goto drop;
 229         }
 230
 231         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 232         /* We should really parse IP options here but until
 233          * somebody who actually uses IP options complains to
 234          * us we'll just silently ignore the options because
 235          * we're lazy!
 236          */
 237         return 0;
 238
 239 inhdr_error:
 240         __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
 241 drop:
 242         return -1;
 243 }
 244
 245 void nf_bridge_update_protocol(struct sk_buff *skb)
 246 {
 247         switch (skb->nf_bridge->orig_proto) {
 248         case BRNF_PROTO_8021Q:
 249                 skb->protocol = htons(ETH_P_8021Q);
 250                 break;
 251         case BRNF_PROTO_PPPOE:
 252                 skb->protocol = htons(ETH_P_PPP_SES);
 253                 break;
 254         case BRNF_PROTO_UNCHANGED:
 255                 break;
 256         }
 257 }
 258
 259 /* Obtain the correct destination MAC address, while preserving the original
 260  * source MAC address. If we already know this address, we just copy it. If we
 261  * don't, we use the neighbour framework to find out. In both cases, we make
 262  * sure that br_handle_frame_finish() is called afterwards.
 263  */
 264 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
 265 {
 266         struct neighbour *neigh;
 267         struct dst_entry *dst;
 268
 269         skb->dev = bridge_parent(skb->dev);
 270         if (!skb->dev)
 271                 goto free_skb;
 272         dst = skb_dst(skb);
 273         neigh = dst_neigh_lookup_skb(dst, skb);
 274         if (neigh) {
 275                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 276                 int ret;
 277
 278                 if (neigh->hh.hh_len) {
 279                         neigh_hh_bridge(&neigh->hh, skb);
 280                         skb->dev = nf_bridge->physindev;
 281                         ret = br_handle_frame_finish(net, sk, skb);
 282                 } else {
 283                         /* the neighbour function below overwrites the complete
 284                          * MAC header, so we save the Ethernet source address and
 285                          * protocol number.
 286                          */
 287                         skb_copy_from_linear_data_offset(skb,
 288                                                          -(ETH_HLEN-ETH_ALEN),
 289                                                          nf_bridge->neigh_header,
 290                                                          ETH_HLEN-ETH_ALEN);
 291                         /* tell br_dev_xmit to continue with forwarding */
 292                         nf_bridge->bridged_dnat = 1;
 293                         /* FIXME Need to refragment */
 294                         ret = neigh->output(neigh, skb);
 295                 }
 296                 neigh_release(neigh);
 297                 return ret;
 298         }
 299 free_skb:
 300         kfree_skb(skb);
 301         return 0;
 302 }
 303
 304 static inline bool
 305 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
 306                              const struct nf_bridge_info *nf_bridge)
 307 {
 308         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
 309 }
 310
 311 /* This requires some explaining. If DNAT has taken place,
 312  * we will need to fix up the destination Ethernet address.
 313  * This is also true when SNAT takes place (for the reply direction).
 314  *
 315  * There are two cases to consider:
 316  * 1. The packet was DNAT'ed to a device in the same bridge
 317  *    port group as it was received on. We can still bridge
 318  *    the packet.
 319  * 2. The packet was DNAT'ed to a different device, either
 320  *    a non-bridged device or another bridge port group.
 321  *    The packet will need to be routed.
 322  *
 323  * The correct way of distinguishing between these two cases is to
 324  * call ip_route_input() and to look at skb->dst->dev, which is
 325  * changed to the destination device if ip_route_input() succeeds.
 326  *
 327  * Let's first consider the case that ip_route_input() succeeds:
 328  *
 329  * If the output device equals the logical bridge device the packet
 330  * came in on, we can consider this bridging. The corresponding MAC
 331  * address will be obtained in br_nf_pre_routing_finish_bridge.
 332  * Otherwise, the packet is considered to be routed and we just
 333  * change the destination MAC address so that the packet will
 334  * later be passed up to the IP stack to be routed. For a redirected
 335  * packet, ip_route_input() will give back the localhost as output device,
 336  * which differs from the bridge device.
 337  *
 338  * Let's now consider the case that ip_route_input() fails:
 339  *
 340  * This can be because the destination address is martian, in which case
 341  * the packet will be dropped.
 342  * If IP forwarding is disabled, ip_route_input() will fail, while
 343  * ip_route_output_key() can return success. The source
 344  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 345  * thinks we're handling a locally generated packet and won't care
 346  * if IP forwarding is enabled. If the output device equals the logical bridge
 347  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 348  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 349  */
 350 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 351 {
 352         struct net_device *dev = skb->dev;
 353         struct iphdr *iph = ip_hdr(skb);
 354         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 355         struct rtable *rt;
 356         int err;
 357
 358         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 359
 360         if (nf_bridge->pkt_otherhost) {
 361                 skb->pkt_type = PACKET_OTHERHOST;
 362                 nf_bridge->pkt_otherhost = false;
 363         }
 364         nf_bridge->in_prerouting = 0;
 365         if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
 366                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 367                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 368
 369                         /* If err equals -EHOSTUNREACH the error is due to a
 370                          * martian destination or due to the fact that
 371                          * forwarding is disabled. For most martian packets,
 372                          * ip_route_output_key() will fail. It won't fail for 2 types of
 373                          * martian destinations: loopback destinations and destination
 374                          * 0.0.0.0. In both cases the packet will be dropped because the
 375                          * destination is the loopback device and not the bridge. */
 376                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 377                                 goto free_skb;
 378
 379                         rt = ip_route_output(net, iph->daddr, 0,
 380                                              RT_TOS(iph->tos), 0);
 381                         if (!IS_ERR(rt)) {
 382                                 /* - Bridged-and-DNAT'ed traffic doesn't
 383                                  *   require ip_forwarding. */
 384                                 if (rt->dst.dev == dev) {
 385                                         skb_dst_set(skb, &rt->dst);
 386                                         goto bridged_dnat;
 387                                 }
 388                                 ip_rt_put(rt);
 389                         }
 390 free_skb:
 391                         kfree_skb(skb);
 392                         return 0;
 393                 } else {
 394                         if (skb_dst(skb)->dev == dev) {
 395 bridged_dnat:
 396                                 skb->dev = nf_bridge->physindev;
 397                                 nf_bridge_update_protocol(skb);
 398                                 nf_bridge_push_encap_header(skb);
 399                                 br_nf_hook_thresh(NF_BR_PRE_ROUTING,
 400                                                   net, sk, skb, skb->dev,
 401                                                   NULL,
 402                                                   br_nf_pre_routing_finish_bridge);
 403                                 return 0;
 404                         }
 405                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
 406                         skb->pkt_type = PACKET_HOST;
 407                 }
 408         } else {
 409                 rt = bridge_parent_rtable(nf_bridge->physindev);
 410                 if (!rt) {
 411                         kfree_skb(skb);
 412                         return 0;
 413                 }
 414                 skb_dst_set_noref(skb, &rt->dst);
 415         }
 416
 417         skb->dev = nf_bridge->physindev;
 418         nf_bridge_update_protocol(skb);
 419         nf_bridge_push_encap_header(skb);
 420         br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL,
 421                           br_handle_frame_finish);
 422         return 0;
 423 }
 424
 425 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
 426 {
 427         struct net_device *vlan, *br;
 428
 429         br = bridge_parent(dev);
 430         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
 431                 return br;
 432
 433         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
 434                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
 435
 436         return vlan ? vlan : br;
 437 }
 438
 439 /* Some common code for IPv4/IPv6 */
 440 struct net_device *setup_pre_routing(struct sk_buff *skb)
 441 {
 442         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 443
 444         if (skb->pkt_type == PACKET_OTHERHOST) {
 445                 skb->pkt_type = PACKET_HOST;
 446                 nf_bridge->pkt_otherhost = true;
 447         }
 448
 449         nf_bridge->in_prerouting = 1;
 450         nf_bridge->physindev = skb->dev;
 451         skb->dev = brnf_get_logical_dev(skb, skb->dev);
 452
 453         if (skb->protocol == htons(ETH_P_8021Q))
 454                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
 455         else if (skb->protocol == htons(ETH_P_PPP_SES))
 456                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
 457
 458         /* Must drop socket now because of tproxy. */
 459         skb_orphan(skb);
 460         return skb->dev;
 461 }
 462
 463 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 464  * Replicate the checks that IPv4 does on packet reception.
 465  * Set skb->dev to the bridge device (i.e. parent of the
 466  * receiving device) to make netfilter happy, the REDIRECT
 467  * target in particular.  Save the original destination IP
 468  * address to be able to detect DNAT afterwards. */
 469 static unsigned int br_nf_pre_routing(void *priv,
 470                                       struct sk_buff *skb,
 471                                       const struct nf_hook_state *state)
 472 {
 473         struct nf_bridge_info *nf_bridge;
 474         struct net_bridge_port *p;
 475         struct net_bridge *br;
 476         __u32 len = nf_bridge_encap_header_len(skb);
 477
 478         if (unlikely(!pskb_may_pull(skb, len)))
 479                 return NF_DROP;
 480
 481         p = br_port_get_rcu(state->in);
 482         if (p == NULL)
 483                 return NF_DROP;
 484         br = p->br;
 485
 486         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
 487                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 488                         return NF_ACCEPT;
 489
 490                 nf_bridge_pull_encap_header_rcsum(skb);
 491                 return br_nf_pre_routing_ipv6(priv, skb, state);
 492         }
 493
 494         if (!brnf_call_iptables && !br->nf_call_iptables)
 495                 return NF_ACCEPT;
 496
 497         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
 498                 return NF_ACCEPT;
 499
 500         nf_bridge_pull_encap_header_rcsum(skb);
 501
 502         if (br_validate_ipv4(state->net, skb))
 503                 return NF_DROP;
 504
 505         nf_bridge_put(skb->nf_bridge);
 506         if (!nf_bridge_alloc(skb))
 507                 return NF_DROP;
 508         if (!setup_pre_routing(skb))
 509                 return NF_DROP;
 510
 511         nf_bridge = nf_bridge_info_get(skb);
 512         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
 513
 514         skb->protocol = htons(ETH_P_IP);
 515
 516         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
 517                 skb->dev, NULL,
 518                 br_nf_pre_routing_finish);
 519
 520         return NF_STOLEN;
 521 }
 522
 523
 524 /* PF_BRIDGE/LOCAL_IN ************************************************/
 525 /* The packet is locally destined, which requires a real
 526  * dst_entry, so detach the fake one.  On the way up, the
 527  * packet would pass through PRE_ROUTING again (which already
 528  * took place when the packet entered the bridge), but we
 529  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 530  * prevent this from happening. */
 531 static unsigned int br_nf_local_in(void *priv,
 532                                    struct sk_buff *skb,
 533                                    const struct nf_hook_state *state)
 534 {
 535         br_drop_fake_rtable(skb);
 536         return NF_ACCEPT;
 537 }
 538
 539 /* PF_BRIDGE/FORWARD *************************************************/
 540 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 541 {
 542         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 543         struct net_device *in;
 544
 545         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
 546
 547                 if (skb->protocol == htons(ETH_P_IP))
 548                         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 549
 550                 if (skb->protocol == htons(ETH_P_IPV6))
 551                         nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 552
 553                 in = nf_bridge->physindev;
 554                 if (nf_bridge->pkt_otherhost) {
 555                         skb->pkt_type = PACKET_OTHERHOST;
 556                         nf_bridge->pkt_otherhost = false;
 557                 }
 558                 nf_bridge_update_protocol(skb);
 559         } else {
 560                 in = *((struct net_device **)(skb->cb));
 561         }
 562         nf_bridge_push_encap_header(skb);
 563
 564         br_nf_hook_thresh(NF_BR_FORWARD, net, sk, skb, in, skb->dev,
 565                           br_forward_finish);
 566         return 0;
 567 }
 568
 569
 570 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 571  * netfilter with indev and outdev set to the bridge device,
 572  * but we are still able to filter on the 'real' indev/outdev
 573  * because of the physdev module. For ARP, indev and outdev are the
 574  * bridge ports. */
 575 static unsigned int br_nf_forward_ip(void *priv,
 576                                      struct sk_buff *skb,
 577                                      const struct nf_hook_state *state)
 578 {
 579         struct nf_bridge_info *nf_bridge;
 580         struct net_device *parent;
 581         u_int8_t pf;
 582
 583         if (!skb->nf_bridge)
 584                 return NF_ACCEPT;
 585
 586         /* Need exclusive nf_bridge_info since we might have multiple
 587          * different physoutdevs. */
 588         if (!nf_bridge_unshare(skb))
 589                 return NF_DROP;
 590
 591         nf_bridge = nf_bridge_info_get(skb);
 592         if (!nf_bridge)
 593                 return NF_DROP;
 594
 595         parent = bridge_parent(state->out);
 596         if (!parent)
 597                 return NF_DROP;
 598
 599         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 600                 pf = NFPROTO_IPV4;
 601         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 602                 pf = NFPROTO_IPV6;
 603         else
 604                 return NF_ACCEPT;
 605
 606         nf_bridge_pull_encap_header(skb);
 607
 608         if (skb->pkt_type == PACKET_OTHERHOST) {
 609                 skb->pkt_type = PACKET_HOST;
 610                 nf_bridge->pkt_otherhost = true;
 611         }
 612
 613         if (pf == NFPROTO_IPV4) {
 614                 if (br_validate_ipv4(state->net, skb))
 615                         return NF_DROP;
 616                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 617         }
 618
 619         if (pf == NFPROTO_IPV6) {
 620                 if (br_validate_ipv6(state->net, skb))
 621                         return NF_DROP;
 622                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 623         }
 624
 625         nf_bridge->physoutdev = skb->dev;
 626         if (pf == NFPROTO_IPV4)
 627                 skb->protocol = htons(ETH_P_IP);
 628         else
 629                 skb->protocol = htons(ETH_P_IPV6);
 630
 631         NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
 632                 brnf_get_logical_dev(skb, state->in),
 633                 parent, br_nf_forward_finish);
 634
 635         return NF_STOLEN;
 636 }
 637
 638 static unsigned int br_nf_forward_arp(void *priv,
 639                                       struct sk_buff *skb,
 640                                       const struct nf_hook_state *state)
 641 {
 642         struct net_bridge_port *p;
 643         struct net_bridge *br;
 644         struct net_device **d = (struct net_device **)(skb->cb);
 645
 646         p = br_port_get_rcu(state->out);
 647         if (p == NULL)
 648                 return NF_ACCEPT;
 649         br = p->br;
 650
 651         if (!brnf_call_arptables && !br->nf_call_arptables)
 652                 return NF_ACCEPT;
 653
 654         if (!IS_ARP(skb)) {
 655                 if (!IS_VLAN_ARP(skb))
 656                         return NF_ACCEPT;
 657                 nf_bridge_pull_encap_header(skb);
 658         }
 659
 660         if (arp_hdr(skb)->ar_pln != 4) {
 661                 if (IS_VLAN_ARP(skb))
 662                         nf_bridge_push_encap_header(skb);
 663                 return NF_ACCEPT;
 664         }
 665         *d = state->in;
 666         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
 667                 state->in, state->out, br_nf_forward_finish);
 668
 669         return NF_STOLEN;
 670 }
 671
 672 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 673 {
 674         struct brnf_frag_data *data;
 675         int err;
 676
 677         data = this_cpu_ptr(&brnf_frag_data_storage);
 678         err = skb_cow_head(skb, data->size);
 679
 680         if (err) {
 681                 kfree_skb(skb);
 682                 return 0;
 683         }
 684
 685         if (data->vlan_tci) {
 686                 skb->vlan_tci = data->vlan_tci;
 687                 skb->vlan_proto = data->vlan_proto;
 688         }
 689
 690         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
 691         __skb_push(skb, data->encap_size);
 692
 693         nf_bridge_info_free(skb);
 694         return br_dev_queue_push_xmit(net, sk, skb);
 695 }
 696
 697 static int
 698 br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 699                   int (*output)(struct net *, struct sock *, struct sk_buff *))
 700 {
 701         unsigned int mtu = ip_skb_dst_mtu(sk, skb);
 702         struct iphdr *iph = ip_hdr(skb);
 703
 704         if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
 705                      (IPCB(skb)->frag_max_size &&
 706                       IPCB(skb)->frag_max_size > mtu))) {
 707                 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 708                 kfree_skb(skb);
 709                 return -EMSGSIZE;
 710         }
 711
 712         return ip_do_fragment(net, sk, skb, output);
 713 }
 714
 715 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
 716 {
 717         if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
 718                 return PPPOE_SES_HLEN;
 719         return 0;
 720 }
 721
 722 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 723 {
 724         struct nf_bridge_info *nf_bridge;
 725         unsigned int mtu_reserved;
 726
 727         mtu_reserved = nf_bridge_mtu_reduction(skb);
 728
 729         if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
 730                 nf_bridge_info_free(skb);
 731                 return br_dev_queue_push_xmit(net, sk, skb);
 732         }
 733
 734         nf_bridge = nf_bridge_info_get(skb);
 735
 736         /* This is wrong! We should preserve the original fragment
 737          * boundaries by preserving frag_list rather than refragmenting.
 738          */
 739         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
 740             skb->protocol == htons(ETH_P_IP)) {
 741                 struct brnf_frag_data *data;
 742
 743                 if (br_validate_ipv4(net, skb))
 744                         goto drop;
 745
 746                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 747
 748                 nf_bridge_update_protocol(skb);
 749
 750                 data = this_cpu_ptr(&brnf_frag_data_storage);
 751
 752                 data->vlan_tci = skb->vlan_tci;
 753                 data->vlan_proto = skb->vlan_proto;
 754                 data->encap_size = nf_bridge_encap_header_len(skb);
 755                 data->size = ETH_HLEN + data->encap_size;
 756
 757                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 758                                                  data->size);
 759
 760                 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
 761         }
 762         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
 763             skb->protocol == htons(ETH_P_IPV6)) {
 764                 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 765                 struct brnf_frag_data *data;
 766
 767                 if (br_validate_ipv6(net, skb))
 768                         goto drop;
 769
 770                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 771
 772                 nf_bridge_update_protocol(skb);
 773
 774                 data = this_cpu_ptr(&brnf_frag_data_storage);
 775                 data->encap_size = nf_bridge_encap_header_len(skb);
 776                 data->size = ETH_HLEN + data->encap_size;
 777
 778                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 779                                                  data->size);
 780
 781                 if (v6ops)
 782                         return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
 783
 784                 kfree_skb(skb);
 785                 return -EMSGSIZE;
 786         }
 787         nf_bridge_info_free(skb);
 788         return br_dev_queue_push_xmit(net, sk, skb);
 789  drop:
 790         kfree_skb(skb);
 791         return 0;
 792 }
 793
 794 /* PF_BRIDGE/POST_ROUTING ********************************************/
 795 static unsigned int br_nf_post_routing(void *priv,
 796                                        struct sk_buff *skb,
 797                                        const struct nf_hook_state *state)
 798 {
 799         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 800         struct net_device *realoutdev = bridge_parent(skb->dev);
 801         u_int8_t pf;
 802
 803         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
 804          * on a bridge, but was delivered locally and is now being routed:
 805          *
 806          * POST_ROUTING was already invoked from the ip stack.
 807          */
 808         if (!nf_bridge || !nf_bridge->physoutdev)
 809                 return NF_ACCEPT;
 810
 811         if (!realoutdev)
 812                 return NF_DROP;
 813
 814         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 815                 pf = NFPROTO_IPV4;
 816         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 817                 pf = NFPROTO_IPV6;
 818         else
 819                 return NF_ACCEPT;
 820
 821         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 822          * about the value of skb->pkt_type. */
 823         if (skb->pkt_type == PACKET_OTHERHOST) {
 824                 skb->pkt_type = PACKET_HOST;
 825                 nf_bridge->pkt_otherhost = true;
 826         }
 827
 828         nf_bridge_pull_encap_header(skb);
 829         if (pf == NFPROTO_IPV4)
 830                 skb->protocol = htons(ETH_P_IP);
 831         else
 832                 skb->protocol = htons(ETH_P_IPV6);
 833
 834         NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
 835                 NULL, realoutdev,
 836                 br_nf_dev_queue_xmit);
 837
 838         return NF_STOLEN;
 839 }
 840
 841 /* IP/SABOTAGE *****************************************************/
 842 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 843  * for the second time. */
 844 static unsigned int ip_sabotage_in(void *priv,
 845                                    struct sk_buff *skb,
 846                                    const struct nf_hook_state *state)
 847 {
 848         if (skb->nf_bridge && !skb->nf_bridge->in_prerouting) {
 849                 state->okfn(state->net, state->sk, skb);
 850                 return NF_STOLEN;
 851         }
 852
 853         return NF_ACCEPT;
 854 }
 855
 856 /* This is called when br_netfilter has called into iptables/netfilter,
 857  * and DNAT has taken place on a bridge-forwarded packet.
 858  *
 859  * neigh->output has created a new MAC header, with local br0 MAC
 860  * as saddr.
 861  *
 862  * This restores the original MAC saddr of the bridged packet
 863  * before invoking bridge forward logic to transmit the packet.
 864  */
 865 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 866 {
 867         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 868
 869         skb_pull(skb, ETH_HLEN);
 870         nf_bridge->bridged_dnat = 0;
 871
 872         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
 873
 874         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
 875                                        nf_bridge->neigh_header,
 876                                        ETH_HLEN - ETH_ALEN);
 877         skb->dev = nf_bridge->physindev;
 878
 879         nf_bridge->physoutdev = NULL;
 880         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 881 }
 882
 883 static int br_nf_dev_xmit(struct sk_buff *skb)
 884 {
 885         if (skb->nf_bridge && skb->nf_bridge->bridged_dnat) {
 886                 br_nf_pre_routing_finish_bridge_slow(skb);
 887                 return 1;
 888         }
 889         return 0;
 890 }
 891
 892 static const struct nf_br_ops br_ops = {
 893         .br_dev_xmit_hook =     br_nf_dev_xmit,
 894 };
 895
 896 void br_netfilter_enable(void)
 897 {
 898 }
 899 EXPORT_SYMBOL_GPL(br_netfilter_enable);
 900
 901 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 902  * br_dev_queue_push_xmit is called afterwards */
 903 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 904         {
 905                 .hook = br_nf_pre_routing,
 906                 .pf = NFPROTO_BRIDGE,
 907                 .hooknum = NF_BR_PRE_ROUTING,
 908                 .priority = NF_BR_PRI_BRNF,
 909         },
 910         {
 911                 .hook = br_nf_local_in,
 912                 .pf = NFPROTO_BRIDGE,
 913                 .hooknum = NF_BR_LOCAL_IN,
 914                 .priority = NF_BR_PRI_BRNF,
 915         },
 916         {
 917                 .hook = br_nf_forward_ip,
 918                 .pf = NFPROTO_BRIDGE,
 919                 .hooknum = NF_BR_FORWARD,
 920                 .priority = NF_BR_PRI_BRNF - 1,
 921         },
 922         {
 923                 .hook = br_nf_forward_arp,
 924                 .pf = NFPROTO_BRIDGE,
 925                 .hooknum = NF_BR_FORWARD,
 926                 .priority = NF_BR_PRI_BRNF,
 927         },
 928         {
 929                 .hook = br_nf_post_routing,
 930                 .pf = NFPROTO_BRIDGE,
 931                 .hooknum = NF_BR_POST_ROUTING,
 932                 .priority = NF_BR_PRI_LAST,
 933         },
 934         {
 935                 .hook = ip_sabotage_in,
 936                 .pf = NFPROTO_IPV4,
 937                 .hooknum = NF_INET_PRE_ROUTING,
 938                 .priority = NF_IP_PRI_FIRST,
 939         },
 940         {
 941                 .hook = ip_sabotage_in,
 942                 .pf = NFPROTO_IPV6,
 943                 .hooknum = NF_INET_PRE_ROUTING,
 944                 .priority = NF_IP6_PRI_FIRST,
 945         },
 946 };
 947
 948 static int brnf_device_event(struct notifier_block *unused, unsigned long event,
 949                              void *ptr)
 950 {
 951         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 952         struct brnf_net *brnet;
 953         struct net *net;
 954         int ret;
 955
 956         if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
 957                 return NOTIFY_DONE;
 958
 959         ASSERT_RTNL();
 960
 961         net = dev_net(dev);
 962         brnet = net_generic(net, brnf_net_id);
 963         if (brnet->enabled)
 964                 return NOTIFY_OK;
 965
 966         ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
 967         if (ret)
 968                 return NOTIFY_BAD;
 969
 970         brnet->enabled = true;
 971         return NOTIFY_OK;
 972 }
 973
 974 static void __net_exit brnf_exit_net(struct net *net)
 975 {
 976         struct brnf_net *brnet = net_generic(net, brnf_net_id);
 977
 978         if (!brnet->enabled)
 979                 return;
 980
 981         nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
 982         brnet->enabled = false;
 983 }
 984
 985 static struct pernet_operations brnf_net_ops __read_mostly = {
 986         .exit = brnf_exit_net,
 987         .id   = &brnf_net_id,
 988         .size = sizeof(struct brnf_net),
 989 };
 990
 991 static struct notifier_block brnf_notifier __read_mostly = {
 992         .notifier_call = brnf_device_event,
 993 };
 994
 995 /* recursively invokes nf_hook_slow (again), skipping already-called
 996  * hooks (< NF_BR_PRI_BRNF).
 997  *
 998  * Called with rcu read lock held.
 999  */
1000 int br_nf_hook_thresh(unsigned int hook, struct net *net,
1001                       struct sock *sk, struct sk_buff *skb,
1002                       struct net_device *indev,
1003                       struct net_device *outdev,
1004                       int (*okfn)(struct net *, struct sock *,
1005                                   struct sk_buff *))
1006 {
1007         struct nf_hook_entry *elem;
1008         struct nf_hook_state state;
1009         int ret;
1010
1011         for (elem = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);
1012              elem && nf_hook_entry_priority(elem) <= NF_BR_PRI_BRNF;
1013              elem = rcu_dereference(elem->next))
1014                 ;
1015
1016         if (!elem)
1017                 return okfn(net, sk, skb);
1018
1019         /* We may already have this, but read-locks nest anyway */
1020         rcu_read_lock();
1021         nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
1022                            sk, net, okfn);
1023
1024         ret = nf_hook_slow(skb, &state, elem);
1025         rcu_read_unlock();
1026         if (ret == 1)
1027                 ret = okfn(net, sk, skb);
1028
1029         return ret;
1030 }
1031
1032 #ifdef CONFIG_SYSCTL
1033 static
1034 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
1035                             void __user *buffer, size_t *lenp, loff_t *ppos)
1036 {
1037         int ret;
1038
1039         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1040
1041         if (write && *(int *)(ctl->data))
1042                 *(int *)(ctl->data) = 1;
1043         return ret;
1044 }
1045
1046 static struct ctl_table brnf_table[] = {
1047         {
1048                 .procname       = "bridge-nf-call-arptables",
1049                 .data           = &brnf_call_arptables,
1050                 .maxlen         = sizeof(int),
1051                 .mode           = 0644,
1052                 .proc_handler   = brnf_sysctl_call_tables,
1053         },
1054         {
1055                 .procname       = "bridge-nf-call-iptables",
1056                 .data           = &brnf_call_iptables,
1057                 .maxlen         = sizeof(int),
1058                 .mode           = 0644,
1059                 .proc_handler   = brnf_sysctl_call_tables,
1060         },
1061         {
1062                 .procname       = "bridge-nf-call-ip6tables",
1063                 .data           = &brnf_call_ip6tables,
1064                 .maxlen         = sizeof(int),
1065                 .mode           = 0644,
1066                 .proc_handler   = brnf_sysctl_call_tables,
1067         },
1068         {
1069                 .procname       = "bridge-nf-filter-vlan-tagged",
1070                 .data           = &brnf_filter_vlan_tagged,
1071                 .maxlen         = sizeof(int),
1072                 .mode           = 0644,
1073                 .proc_handler   = brnf_sysctl_call_tables,
1074         },
1075         {
1076                 .procname       = "bridge-nf-filter-pppoe-tagged",
1077                 .data           = &brnf_filter_pppoe_tagged,
1078                 .maxlen         = sizeof(int),
1079                 .mode           = 0644,
1080                 .proc_handler   = brnf_sysctl_call_tables,
1081         },
1082         {
1083                 .procname       = "bridge-nf-pass-vlan-input-dev",
1084                 .data           = &brnf_pass_vlan_indev,
1085                 .maxlen         = sizeof(int),
1086                 .mode           = 0644,
1087                 .proc_handler   = brnf_sysctl_call_tables,
1088         },
1089         { }
1090 };
1091 #endif
1092
1093 static int __init br_netfilter_init(void)
1094 {
1095         int ret;
1096
1097         ret = register_pernet_subsys(&brnf_net_ops);
1098         if (ret < 0)
1099                 return ret;
1100
1101         ret = register_netdevice_notifier(&brnf_notifier);
1102         if (ret < 0) {
1103                 unregister_pernet_subsys(&brnf_net_ops);
1104                 return ret;
1105         }
1106
1107 #ifdef CONFIG_SYSCTL
1108         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1109         if (brnf_sysctl_header == NULL) {
1110                 printk(KERN_WARNING
1111                        "br_netfilter: can't register to sysctl.\n");
1112                 unregister_netdevice_notifier(&brnf_notifier);
1113                 unregister_pernet_subsys(&brnf_net_ops);
1114                 return -ENOMEM;
1115         }
1116 #endif
1117         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1118         printk(KERN_NOTICE "Bridge firewalling registered\n");
1119         return 0;
1120 }
1121
1122 static void __exit br_netfilter_fini(void)
1123 {
1124         RCU_INIT_POINTER(nf_br_ops, NULL);
1125         unregister_netdevice_notifier(&brnf_notifier);
1126         unregister_pernet_subsys(&brnf_net_ops);
1127 #ifdef CONFIG_SYSCTL
1128         unregister_net_sysctl_table(brnf_sysctl_header);
1129 #endif
1130 }
1131
1132 module_init(br_netfilter_init);
1133 module_exit(br_netfilter_fini);
1134
1135 MODULE_LICENSE("GPL");
1136 MODULE_AUTHOR("Lennert Buytenhek <[email protected]>");
1137 MODULE_AUTHOR("Bart De Schuymer <[email protected]>");
1138 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");