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 <uapi/linux/netfilter_bridge.h>
  30 #include <linux/netfilter_ipv4.h>
  31 #include <linux/netfilter_ipv6.h>
  32 #include <linux/netfilter_arp.h>
  33 #include <linux/in_route.h>
  34 #include <linux/rculist.h>
  35 #include <linux/inetdevice.h>
  36
  37 #include <net/ip.h>
  38 #include <net/ipv6.h>
  39 #include <net/addrconf.h>
  40 #include <net/route.h>
  41 #include <net/netfilter/br_netfilter.h>
  42 #include <net/netns/generic.h>
  43
  44 #include <linux/uaccess.h>
  45 #include "br_private.h"
  46 #ifdef CONFIG_SYSCTL
  47 #include <linux/sysctl.h>
  48 #endif
  49
  50 static unsigned int brnf_net_id __read_mostly;
  51
  52 struct brnf_net {
  53         bool enabled;
  54 };
  55
  56 #ifdef CONFIG_SYSCTL
  57 static struct ctl_table_header *brnf_sysctl_header;
  58 static int brnf_call_iptables __read_mostly = 1;
  59 static int brnf_call_ip6tables __read_mostly = 1;
  60 static int brnf_call_arptables __read_mostly = 1;
  61 static int brnf_filter_vlan_tagged __read_mostly;
  62 static int brnf_filter_pppoe_tagged __read_mostly;
  63 static int brnf_pass_vlan_indev __read_mostly;
  64 #else
  65 #define brnf_call_iptables 1
  66 #define brnf_call_ip6tables 1
  67 #define brnf_call_arptables 1
  68 #define brnf_filter_vlan_tagged 0
  69 #define brnf_filter_pppoe_tagged 0
  70 #define brnf_pass_vlan_indev 0
  71 #endif
  72
  73 #define IS_IP(skb) \
  74         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
  75
  76 #define IS_IPV6(skb) \
  77         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
  78
  79 #define IS_ARP(skb) \
  80         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
  81
  82 static inline __be16 vlan_proto(const struct sk_buff *skb)
  83 {
  84         if (skb_vlan_tag_present(skb))
  85                 return skb->protocol;
  86         else if (skb->protocol == htons(ETH_P_8021Q))
  87                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  88         else
  89                 return 0;
  90 }
  91
  92 #define IS_VLAN_IP(skb) \
  93         (vlan_proto(skb) == htons(ETH_P_IP) && \
  94          brnf_filter_vlan_tagged)
  95
  96 #define IS_VLAN_IPV6(skb) \
  97         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  98          brnf_filter_vlan_tagged)
  99
 100 #define IS_VLAN_ARP(skb) \
 101         (vlan_proto(skb) == htons(ETH_P_ARP) && \
 102          brnf_filter_vlan_tagged)
 103
 104 static inline __be16 pppoe_proto(const struct sk_buff *skb)
 105 {
 106         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
 107                             sizeof(struct pppoe_hdr)));
 108 }
 109
 110 #define IS_PPPOE_IP(skb) \
 111         (skb->protocol == htons(ETH_P_PPP_SES) && \
 112          pppoe_proto(skb) == htons(PPP_IP) && \
 113          brnf_filter_pppoe_tagged)
 114
 115 #define IS_PPPOE_IPV6(skb) \
 116         (skb->protocol == htons(ETH_P_PPP_SES) && \
 117          pppoe_proto(skb) == htons(PPP_IPV6) && \
 118          brnf_filter_pppoe_tagged)
 119
 120 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
 121 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
 122
 123 struct brnf_frag_data {
 124         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
 125         u8 encap_size;
 126         u8 size;
 127         u16 vlan_tci;
 128         __be16 vlan_proto;
 129 };
 130
 131 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
 132
 133 static void nf_bridge_info_free(struct sk_buff *skb)
 134 {
 135         skb_ext_del(skb, SKB_EXT_BRIDGE_NF);
 136 }
 137
 138 static inline struct net_device *bridge_parent(const struct net_device *dev)
 139 {
 140         struct net_bridge_port *port;
 141
 142         port = br_port_get_rcu(dev);
 143         return port ? port->br->dev : NULL;
 144 }
 145
 146 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 147 {
 148         return skb_ext_add(skb, SKB_EXT_BRIDGE_NF);
 149 }
 150
 151 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
 152 {
 153         switch (skb->protocol) {
 154         case __cpu_to_be16(ETH_P_8021Q):
 155                 return VLAN_HLEN;
 156         case __cpu_to_be16(ETH_P_PPP_SES):
 157                 return PPPOE_SES_HLEN;
 158         default:
 159                 return 0;
 160         }
 161 }
 162
 163 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 164 {
 165         unsigned int len = nf_bridge_encap_header_len(skb);
 166
 167         skb_pull(skb, len);
 168         skb->network_header += len;
 169 }
 170
 171 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 172 {
 173         unsigned int len = nf_bridge_encap_header_len(skb);
 174
 175         skb_pull_rcsum(skb, len);
 176         skb->network_header += len;
 177 }
 178
 179 /* When handing a packet over to the IP layer
 180  * check whether we have a skb that is in the
 181  * expected format
 182  */
 183
 184 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
 185 {
 186         const struct iphdr *iph;
 187         u32 len;
 188
 189         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
 190                 goto inhdr_error;
 191
 192         iph = ip_hdr(skb);
 193
 194         /* Basic sanity checks */
 195         if (iph->ihl < 5 || iph->version != 4)
 196                 goto inhdr_error;
 197
 198         if (!pskb_may_pull(skb, iph->ihl*4))
 199                 goto inhdr_error;
 200
 201         iph = ip_hdr(skb);
 202         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 203                 goto csum_error;
 204
 205         len = ntohs(iph->tot_len);
 206         if (skb->len < len) {
 207                 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
 208                 goto drop;
 209         } else if (len < (iph->ihl*4))
 210                 goto inhdr_error;
 211
 212         if (pskb_trim_rcsum(skb, len)) {
 213                 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
 214                 goto drop;
 215         }
 216
 217         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 218         /* We should really parse IP options here but until
 219          * somebody who actually uses IP options complains to
 220          * us we'll just silently ignore the options because
 221          * we're lazy!
 222          */
 223         return 0;
 224
 225 csum_error:
 226         __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
 227 inhdr_error:
 228         __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
 229 drop:
 230         return -1;
 231 }
 232
 233 void nf_bridge_update_protocol(struct sk_buff *skb)
 234 {
 235         const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 236
 237         switch (nf_bridge->orig_proto) {
 238         case BRNF_PROTO_8021Q:
 239                 skb->protocol = htons(ETH_P_8021Q);
 240                 break;
 241         case BRNF_PROTO_PPPOE:
 242                 skb->protocol = htons(ETH_P_PPP_SES);
 243                 break;
 244         case BRNF_PROTO_UNCHANGED:
 245                 break;
 246         }
 247 }
 248
 249 /* Obtain the correct destination MAC address, while preserving the original
 250  * source MAC address. If we already know this address, we just copy it. If we
 251  * don't, we use the neighbour framework to find out. In both cases, we make
 252  * sure that br_handle_frame_finish() is called afterwards.
 253  */
 254 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
 255 {
 256         struct neighbour *neigh;
 257         struct dst_entry *dst;
 258
 259         skb->dev = bridge_parent(skb->dev);
 260         if (!skb->dev)
 261                 goto free_skb;
 262         dst = skb_dst(skb);
 263         neigh = dst_neigh_lookup_skb(dst, skb);
 264         if (neigh) {
 265                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 266                 int ret;
 267
 268                 if ((neigh->nud_state & NUD_CONNECTED) && neigh->hh.hh_len) {
 269                         neigh_hh_bridge(&neigh->hh, skb);
 270                         skb->dev = nf_bridge->physindev;
 271                         ret = br_handle_frame_finish(net, sk, skb);
 272                 } else {
 273                         /* the neighbour function below overwrites the complete
 274                          * MAC header, so we save the Ethernet source address and
 275                          * protocol number.
 276                          */
 277                         skb_copy_from_linear_data_offset(skb,
 278                                                          -(ETH_HLEN-ETH_ALEN),
 279                                                          nf_bridge->neigh_header,
 280                                                          ETH_HLEN-ETH_ALEN);
 281                         /* tell br_dev_xmit to continue with forwarding */
 282                         nf_bridge->bridged_dnat = 1;
 283                         /* FIXME Need to refragment */
 284                         ret = neigh->output(neigh, skb);
 285                 }
 286                 neigh_release(neigh);
 287                 return ret;
 288         }
 289 free_skb:
 290         kfree_skb(skb);
 291         return 0;
 292 }
 293
 294 static inline bool
 295 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
 296                              const struct nf_bridge_info *nf_bridge)
 297 {
 298         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
 299 }
 300
 301 /* This requires some explaining. If DNAT has taken place,
 302  * we will need to fix up the destination Ethernet address.
 303  * This is also true when SNAT takes place (for the reply direction).
 304  *
 305  * There are two cases to consider:
 306  * 1. The packet was DNAT'ed to a device in the same bridge
 307  *    port group as it was received on. We can still bridge
 308  *    the packet.
 309  * 2. The packet was DNAT'ed to a different device, either
 310  *    a non-bridged device or another bridge port group.
 311  *    The packet will need to be routed.
 312  *
 313  * The correct way of distinguishing between these two cases is to
 314  * call ip_route_input() and to look at skb->dst->dev, which is
 315  * changed to the destination device if ip_route_input() succeeds.
 316  *
 317  * Let's first consider the case that ip_route_input() succeeds:
 318  *
 319  * If the output device equals the logical bridge device the packet
 320  * came in on, we can consider this bridging. The corresponding MAC
 321  * address will be obtained in br_nf_pre_routing_finish_bridge.
 322  * Otherwise, the packet is considered to be routed and we just
 323  * change the destination MAC address so that the packet will
 324  * later be passed up to the IP stack to be routed. For a redirected
 325  * packet, ip_route_input() will give back the localhost as output device,
 326  * which differs from the bridge device.
 327  *
 328  * Let's now consider the case that ip_route_input() fails:
 329  *
 330  * This can be because the destination address is martian, in which case
 331  * the packet will be dropped.
 332  * If IP forwarding is disabled, ip_route_input() will fail, while
 333  * ip_route_output_key() can return success. The source
 334  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 335  * thinks we're handling a locally generated packet and won't care
 336  * if IP forwarding is enabled. If the output device equals the logical bridge
 337  * device, we proceed as if ip_route_input() succeeded. If it differs from the
 338  * logical bridge port or if ip_route_output_key() fails we drop the packet.
 339  */
 340 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 341 {
 342         struct net_device *dev = skb->dev;
 343         struct iphdr *iph = ip_hdr(skb);
 344         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 345         struct rtable *rt;
 346         int err;
 347
 348         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 349
 350         if (nf_bridge->pkt_otherhost) {
 351                 skb->pkt_type = PACKET_OTHERHOST;
 352                 nf_bridge->pkt_otherhost = false;
 353         }
 354         nf_bridge->in_prerouting = 0;
 355         if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
 356                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 357                         struct in_device *in_dev = __in_dev_get_rcu(dev);
 358
 359                         /* If err equals -EHOSTUNREACH the error is due to a
 360                          * martian destination or due to the fact that
 361                          * forwarding is disabled. For most martian packets,
 362                          * ip_route_output_key() will fail. It won't fail for 2 types of
 363                          * martian destinations: loopback destinations and destination
 364                          * 0.0.0.0. In both cases the packet will be dropped because the
 365                          * destination is the loopback device and not the bridge. */
 366                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 367                                 goto free_skb;
 368
 369                         rt = ip_route_output(net, iph->daddr, 0,
 370                                              RT_TOS(iph->tos), 0);
 371                         if (!IS_ERR(rt)) {
 372                                 /* - Bridged-and-DNAT'ed traffic doesn't
 373                                  *   require ip_forwarding. */
 374                                 if (rt->dst.dev == dev) {
 375                                         skb_dst_set(skb, &rt->dst);
 376                                         goto bridged_dnat;
 377                                 }
 378                                 ip_rt_put(rt);
 379                         }
 380 free_skb:
 381                         kfree_skb(skb);
 382                         return 0;
 383                 } else {
 384                         if (skb_dst(skb)->dev == dev) {
 385 bridged_dnat:
 386                                 skb->dev = nf_bridge->physindev;
 387                                 nf_bridge_update_protocol(skb);
 388                                 nf_bridge_push_encap_header(skb);
 389                                 br_nf_hook_thresh(NF_BR_PRE_ROUTING,
 390                                                   net, sk, skb, skb->dev,
 391                                                   NULL,
 392                                                   br_nf_pre_routing_finish_bridge);
 393                                 return 0;
 394                         }
 395                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
 396                         skb->pkt_type = PACKET_HOST;
 397                 }
 398         } else {
 399                 rt = bridge_parent_rtable(nf_bridge->physindev);
 400                 if (!rt) {
 401                         kfree_skb(skb);
 402                         return 0;
 403                 }
 404                 skb_dst_set_noref(skb, &rt->dst);
 405         }
 406
 407         skb->dev = nf_bridge->physindev;
 408         nf_bridge_update_protocol(skb);
 409         nf_bridge_push_encap_header(skb);
 410         br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL,
 411                           br_handle_frame_finish);
 412         return 0;
 413 }
 414
 415 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
 416 {
 417         struct net_device *vlan, *br;
 418
 419         br = bridge_parent(dev);
 420         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
 421                 return br;
 422
 423         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
 424                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
 425
 426         return vlan ? vlan : br;
 427 }
 428
 429 /* Some common code for IPv4/IPv6 */
 430 struct net_device *setup_pre_routing(struct sk_buff *skb)
 431 {
 432         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 433
 434         if (skb->pkt_type == PACKET_OTHERHOST) {
 435                 skb->pkt_type = PACKET_HOST;
 436                 nf_bridge->pkt_otherhost = true;
 437         }
 438
 439         nf_bridge->in_prerouting = 1;
 440         nf_bridge->physindev = skb->dev;
 441         skb->dev = brnf_get_logical_dev(skb, skb->dev);
 442
 443         if (skb->protocol == htons(ETH_P_8021Q))
 444                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
 445         else if (skb->protocol == htons(ETH_P_PPP_SES))
 446                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
 447
 448         /* Must drop socket now because of tproxy. */
 449         skb_orphan(skb);
 450         return skb->dev;
 451 }
 452
 453 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 454  * Replicate the checks that IPv4 does on packet reception.
 455  * Set skb->dev to the bridge device (i.e. parent of the
 456  * receiving device) to make netfilter happy, the REDIRECT
 457  * target in particular.  Save the original destination IP
 458  * address to be able to detect DNAT afterwards. */
 459 static unsigned int br_nf_pre_routing(void *priv,
 460                                       struct sk_buff *skb,
 461                                       const struct nf_hook_state *state)
 462 {
 463         struct nf_bridge_info *nf_bridge;
 464         struct net_bridge_port *p;
 465         struct net_bridge *br;
 466         __u32 len = nf_bridge_encap_header_len(skb);
 467
 468         if (unlikely(!pskb_may_pull(skb, len)))
 469                 return NF_DROP;
 470
 471         p = br_port_get_rcu(state->in);
 472         if (p == NULL)
 473                 return NF_DROP;
 474         br = p->br;
 475
 476         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
 477                 if (!brnf_call_ip6tables &&
 478                     !br_opt_get(br, BROPT_NF_CALL_IP6TABLES))
 479                         return NF_ACCEPT;
 480
 481                 nf_bridge_pull_encap_header_rcsum(skb);
 482                 return br_nf_pre_routing_ipv6(priv, skb, state);
 483         }
 484
 485         if (!brnf_call_iptables && !br_opt_get(br, BROPT_NF_CALL_IPTABLES))
 486                 return NF_ACCEPT;
 487
 488         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
 489                 return NF_ACCEPT;
 490
 491         nf_bridge_pull_encap_header_rcsum(skb);
 492
 493         if (br_validate_ipv4(state->net, skb))
 494                 return NF_DROP;
 495
 496         if (!nf_bridge_alloc(skb))
 497                 return NF_DROP;
 498         if (!setup_pre_routing(skb))
 499                 return NF_DROP;
 500
 501         nf_bridge = nf_bridge_info_get(skb);
 502         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
 503
 504         skb->protocol = htons(ETH_P_IP);
 505
 506         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
 507                 skb->dev, NULL,
 508                 br_nf_pre_routing_finish);
 509
 510         return NF_STOLEN;
 511 }
 512
 513
 514 /* PF_BRIDGE/FORWARD *************************************************/
 515 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 516 {
 517         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 518         struct net_device *in;
 519
 520         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
 521
 522                 if (skb->protocol == htons(ETH_P_IP))
 523                         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 524
 525                 if (skb->protocol == htons(ETH_P_IPV6))
 526                         nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 527
 528                 in = nf_bridge->physindev;
 529                 if (nf_bridge->pkt_otherhost) {
 530                         skb->pkt_type = PACKET_OTHERHOST;
 531                         nf_bridge->pkt_otherhost = false;
 532                 }
 533                 nf_bridge_update_protocol(skb);
 534         } else {
 535                 in = *((struct net_device **)(skb->cb));
 536         }
 537         nf_bridge_push_encap_header(skb);
 538
 539         br_nf_hook_thresh(NF_BR_FORWARD, net, sk, skb, in, skb->dev,
 540                           br_forward_finish);
 541         return 0;
 542 }
 543
 544
 545 /* This is the 'purely bridged' case.  For IP, we pass the packet to
 546  * netfilter with indev and outdev set to the bridge device,
 547  * but we are still able to filter on the 'real' indev/outdev
 548  * because of the physdev module. For ARP, indev and outdev are the
 549  * bridge ports. */
 550 static unsigned int br_nf_forward_ip(void *priv,
 551                                      struct sk_buff *skb,
 552                                      const struct nf_hook_state *state)
 553 {
 554         struct nf_bridge_info *nf_bridge;
 555         struct net_device *parent;
 556         u_int8_t pf;
 557
 558         nf_bridge = nf_bridge_info_get(skb);
 559         if (!nf_bridge)
 560                 return NF_ACCEPT;
 561
 562         /* Need exclusive nf_bridge_info since we might have multiple
 563          * different physoutdevs. */
 564         if (!nf_bridge_unshare(skb))
 565                 return NF_DROP;
 566
 567         nf_bridge = nf_bridge_info_get(skb);
 568         if (!nf_bridge)
 569                 return NF_DROP;
 570
 571         parent = bridge_parent(state->out);
 572         if (!parent)
 573                 return NF_DROP;
 574
 575         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 576                 pf = NFPROTO_IPV4;
 577         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 578                 pf = NFPROTO_IPV6;
 579         else
 580                 return NF_ACCEPT;
 581
 582         nf_bridge_pull_encap_header(skb);
 583
 584         if (skb->pkt_type == PACKET_OTHERHOST) {
 585                 skb->pkt_type = PACKET_HOST;
 586                 nf_bridge->pkt_otherhost = true;
 587         }
 588
 589         if (pf == NFPROTO_IPV4) {
 590                 if (br_validate_ipv4(state->net, skb))
 591                         return NF_DROP;
 592                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 593         }
 594
 595         if (pf == NFPROTO_IPV6) {
 596                 if (br_validate_ipv6(state->net, skb))
 597                         return NF_DROP;
 598                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 599         }
 600
 601         nf_bridge->physoutdev = skb->dev;
 602         if (pf == NFPROTO_IPV4)
 603                 skb->protocol = htons(ETH_P_IP);
 604         else
 605                 skb->protocol = htons(ETH_P_IPV6);
 606
 607         NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
 608                 brnf_get_logical_dev(skb, state->in),
 609                 parent, br_nf_forward_finish);
 610
 611         return NF_STOLEN;
 612 }
 613
 614 static unsigned int br_nf_forward_arp(void *priv,
 615                                       struct sk_buff *skb,
 616                                       const struct nf_hook_state *state)
 617 {
 618         struct net_bridge_port *p;
 619         struct net_bridge *br;
 620         struct net_device **d = (struct net_device **)(skb->cb);
 621
 622         p = br_port_get_rcu(state->out);
 623         if (p == NULL)
 624                 return NF_ACCEPT;
 625         br = p->br;
 626
 627         if (!brnf_call_arptables && !br_opt_get(br, BROPT_NF_CALL_ARPTABLES))
 628                 return NF_ACCEPT;
 629
 630         if (!IS_ARP(skb)) {
 631                 if (!IS_VLAN_ARP(skb))
 632                         return NF_ACCEPT;
 633                 nf_bridge_pull_encap_header(skb);
 634         }
 635
 636         if (arp_hdr(skb)->ar_pln != 4) {
 637                 if (IS_VLAN_ARP(skb))
 638                         nf_bridge_push_encap_header(skb);
 639                 return NF_ACCEPT;
 640         }
 641         *d = state->in;
 642         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
 643                 state->in, state->out, br_nf_forward_finish);
 644
 645         return NF_STOLEN;
 646 }
 647
 648 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 649 {
 650         struct brnf_frag_data *data;
 651         int err;
 652
 653         data = this_cpu_ptr(&brnf_frag_data_storage);
 654         err = skb_cow_head(skb, data->size);
 655
 656         if (err) {
 657                 kfree_skb(skb);
 658                 return 0;
 659         }
 660
 661         if (data->vlan_proto)
 662                 __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
 663
 664         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
 665         __skb_push(skb, data->encap_size);
 666
 667         nf_bridge_info_free(skb);
 668         return br_dev_queue_push_xmit(net, sk, skb);
 669 }
 670
 671 static int
 672 br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
 673                   int (*output)(struct net *, struct sock *, struct sk_buff *))
 674 {
 675         unsigned int mtu = ip_skb_dst_mtu(sk, skb);
 676         struct iphdr *iph = ip_hdr(skb);
 677
 678         if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
 679                      (IPCB(skb)->frag_max_size &&
 680                       IPCB(skb)->frag_max_size > mtu))) {
 681                 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
 682                 kfree_skb(skb);
 683                 return -EMSGSIZE;
 684         }
 685
 686         return ip_do_fragment(net, sk, skb, output);
 687 }
 688
 689 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
 690 {
 691         const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 692
 693         if (nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
 694                 return PPPOE_SES_HLEN;
 695         return 0;
 696 }
 697
 698 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 699 {
 700         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 701         unsigned int mtu, mtu_reserved;
 702
 703         mtu_reserved = nf_bridge_mtu_reduction(skb);
 704         mtu = skb->dev->mtu;
 705
 706         if (nf_bridge->frag_max_size && nf_bridge->frag_max_size < mtu)
 707                 mtu = nf_bridge->frag_max_size;
 708
 709         if (skb_is_gso(skb) || skb->len + mtu_reserved <= mtu) {
 710                 nf_bridge_info_free(skb);
 711                 return br_dev_queue_push_xmit(net, sk, skb);
 712         }
 713
 714         /* This is wrong! We should preserve the original fragment
 715          * boundaries by preserving frag_list rather than refragmenting.
 716          */
 717         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
 718             skb->protocol == htons(ETH_P_IP)) {
 719                 struct brnf_frag_data *data;
 720
 721                 if (br_validate_ipv4(net, skb))
 722                         goto drop;
 723
 724                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
 725
 726                 nf_bridge_update_protocol(skb);
 727
 728                 data = this_cpu_ptr(&brnf_frag_data_storage);
 729
 730                 if (skb_vlan_tag_present(skb)) {
 731                         data->vlan_tci = skb->vlan_tci;
 732                         data->vlan_proto = skb->vlan_proto;
 733                 } else {
 734                         data->vlan_proto = 0;
 735                 }
 736
 737                 data->encap_size = nf_bridge_encap_header_len(skb);
 738                 data->size = ETH_HLEN + data->encap_size;
 739
 740                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 741                                                  data->size);
 742
 743                 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
 744         }
 745         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
 746             skb->protocol == htons(ETH_P_IPV6)) {
 747                 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 748                 struct brnf_frag_data *data;
 749
 750                 if (br_validate_ipv6(net, skb))
 751                         goto drop;
 752
 753                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
 754
 755                 nf_bridge_update_protocol(skb);
 756
 757                 data = this_cpu_ptr(&brnf_frag_data_storage);
 758                 data->encap_size = nf_bridge_encap_header_len(skb);
 759                 data->size = ETH_HLEN + data->encap_size;
 760
 761                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
 762                                                  data->size);
 763
 764                 if (v6ops)
 765                         return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
 766
 767                 kfree_skb(skb);
 768                 return -EMSGSIZE;
 769         }
 770         nf_bridge_info_free(skb);
 771         return br_dev_queue_push_xmit(net, sk, skb);
 772  drop:
 773         kfree_skb(skb);
 774         return 0;
 775 }
 776
 777 /* PF_BRIDGE/POST_ROUTING ********************************************/
 778 static unsigned int br_nf_post_routing(void *priv,
 779                                        struct sk_buff *skb,
 780                                        const struct nf_hook_state *state)
 781 {
 782         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 783         struct net_device *realoutdev = bridge_parent(skb->dev);
 784         u_int8_t pf;
 785
 786         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
 787          * on a bridge, but was delivered locally and is now being routed:
 788          *
 789          * POST_ROUTING was already invoked from the ip stack.
 790          */
 791         if (!nf_bridge || !nf_bridge->physoutdev)
 792                 return NF_ACCEPT;
 793
 794         if (!realoutdev)
 795                 return NF_DROP;
 796
 797         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 798                 pf = NFPROTO_IPV4;
 799         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 800                 pf = NFPROTO_IPV6;
 801         else
 802                 return NF_ACCEPT;
 803
 804         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 805          * about the value of skb->pkt_type. */
 806         if (skb->pkt_type == PACKET_OTHERHOST) {
 807                 skb->pkt_type = PACKET_HOST;
 808                 nf_bridge->pkt_otherhost = true;
 809         }
 810
 811         nf_bridge_pull_encap_header(skb);
 812         if (pf == NFPROTO_IPV4)
 813                 skb->protocol = htons(ETH_P_IP);
 814         else
 815                 skb->protocol = htons(ETH_P_IPV6);
 816
 817         NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
 818                 NULL, realoutdev,
 819                 br_nf_dev_queue_xmit);
 820
 821         return NF_STOLEN;
 822 }
 823
 824 /* IP/SABOTAGE *****************************************************/
 825 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 826  * for the second time. */
 827 static unsigned int ip_sabotage_in(void *priv,
 828                                    struct sk_buff *skb,
 829                                    const struct nf_hook_state *state)
 830 {
 831         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 832
 833         if (nf_bridge && !nf_bridge->in_prerouting &&
 834             !netif_is_l3_master(skb->dev)) {
 835                 state->okfn(state->net, state->sk, skb);
 836                 return NF_STOLEN;
 837         }
 838
 839         return NF_ACCEPT;
 840 }
 841
 842 /* This is called when br_netfilter has called into iptables/netfilter,
 843  * and DNAT has taken place on a bridge-forwarded packet.
 844  *
 845  * neigh->output has created a new MAC header, with local br0 MAC
 846  * as saddr.
 847  *
 848  * This restores the original MAC saddr of the bridged packet
 849  * before invoking bridge forward logic to transmit the packet.
 850  */
 851 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 852 {
 853         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 854
 855         skb_pull(skb, ETH_HLEN);
 856         nf_bridge->bridged_dnat = 0;
 857
 858         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
 859
 860         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
 861                                        nf_bridge->neigh_header,
 862                                        ETH_HLEN - ETH_ALEN);
 863         skb->dev = nf_bridge->physindev;
 864
 865         nf_bridge->physoutdev = NULL;
 866         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
 867 }
 868
 869 static int br_nf_dev_xmit(struct sk_buff *skb)
 870 {
 871         const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 872
 873         if (nf_bridge && nf_bridge->bridged_dnat) {
 874                 br_nf_pre_routing_finish_bridge_slow(skb);
 875                 return 1;
 876         }
 877         return 0;
 878 }
 879
 880 static const struct nf_br_ops br_ops = {
 881         .br_dev_xmit_hook =     br_nf_dev_xmit,
 882 };
 883
 884 void br_netfilter_enable(void)
 885 {
 886 }
 887 EXPORT_SYMBOL_GPL(br_netfilter_enable);
 888
 889 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 890  * br_dev_queue_push_xmit is called afterwards */
 891 static const struct nf_hook_ops br_nf_ops[] = {
 892         {
 893                 .hook = br_nf_pre_routing,
 894                 .pf = NFPROTO_BRIDGE,
 895                 .hooknum = NF_BR_PRE_ROUTING,
 896                 .priority = NF_BR_PRI_BRNF,
 897         },
 898         {
 899                 .hook = br_nf_forward_ip,
 900                 .pf = NFPROTO_BRIDGE,
 901                 .hooknum = NF_BR_FORWARD,
 902                 .priority = NF_BR_PRI_BRNF - 1,
 903         },
 904         {
 905                 .hook = br_nf_forward_arp,
 906                 .pf = NFPROTO_BRIDGE,
 907                 .hooknum = NF_BR_FORWARD,
 908                 .priority = NF_BR_PRI_BRNF,
 909         },
 910         {
 911                 .hook = br_nf_post_routing,
 912                 .pf = NFPROTO_BRIDGE,
 913                 .hooknum = NF_BR_POST_ROUTING,
 914                 .priority = NF_BR_PRI_LAST,
 915         },
 916         {
 917                 .hook = ip_sabotage_in,
 918                 .pf = NFPROTO_IPV4,
 919                 .hooknum = NF_INET_PRE_ROUTING,
 920                 .priority = NF_IP_PRI_FIRST,
 921         },
 922         {
 923                 .hook = ip_sabotage_in,
 924                 .pf = NFPROTO_IPV6,
 925                 .hooknum = NF_INET_PRE_ROUTING,
 926                 .priority = NF_IP6_PRI_FIRST,
 927         },
 928 };
 929
 930 static int brnf_device_event(struct notifier_block *unused, unsigned long event,
 931                              void *ptr)
 932 {
 933         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 934         struct brnf_net *brnet;
 935         struct net *net;
 936         int ret;
 937
 938         if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
 939                 return NOTIFY_DONE;
 940
 941         ASSERT_RTNL();
 942
 943         net = dev_net(dev);
 944         brnet = net_generic(net, brnf_net_id);
 945         if (brnet->enabled)
 946                 return NOTIFY_OK;
 947
 948         ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
 949         if (ret)
 950                 return NOTIFY_BAD;
 951
 952         brnet->enabled = true;
 953         return NOTIFY_OK;
 954 }
 955
 956 static void __net_exit brnf_exit_net(struct net *net)
 957 {
 958         struct brnf_net *brnet = net_generic(net, brnf_net_id);
 959
 960         if (!brnet->enabled)
 961                 return;
 962
 963         nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
 964         brnet->enabled = false;
 965 }
 966
 967 static struct pernet_operations brnf_net_ops __read_mostly = {
 968         .exit = brnf_exit_net,
 969         .id   = &brnf_net_id,
 970         .size = sizeof(struct brnf_net),
 971 };
 972
 973 static struct notifier_block brnf_notifier __read_mostly = {
 974         .notifier_call = brnf_device_event,
 975 };
 976
 977 /* recursively invokes nf_hook_slow (again), skipping already-called
 978  * hooks (< NF_BR_PRI_BRNF).
 979  *
 980  * Called with rcu read lock held.
 981  */
 982 int br_nf_hook_thresh(unsigned int hook, struct net *net,
 983                       struct sock *sk, struct sk_buff *skb,
 984                       struct net_device *indev,
 985                       struct net_device *outdev,
 986                       int (*okfn)(struct net *, struct sock *,
 987                                   struct sk_buff *))
 988 {
 989         const struct nf_hook_entries *e;
 990         struct nf_hook_state state;
 991         struct nf_hook_ops **ops;
 992         unsigned int i;
 993         int ret;
 994
 995         e = rcu_dereference(net->nf.hooks_bridge[hook]);
 996         if (!e)
 997                 return okfn(net, sk, skb);
 998
 999         ops = nf_hook_entries_get_hook_ops(e);
1000         for (i = 0; i < e->num_hook_entries &&
1001               ops[i]->priority <= NF_BR_PRI_BRNF; i++)
1002                 ;
1003
1004         nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
1005                            sk, net, okfn);
1006
1007         ret = nf_hook_slow(skb, &state, e, i);
1008         if (ret == 1)
1009                 ret = okfn(net, sk, skb);
1010
1011         return ret;
1012 }
1013
1014 #ifdef CONFIG_SYSCTL
1015 static
1016 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
1017                             void __user *buffer, size_t *lenp, loff_t *ppos)
1018 {
1019         int ret;
1020
1021         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1022
1023         if (write && *(int *)(ctl->data))
1024                 *(int *)(ctl->data) = 1;
1025         return ret;
1026 }
1027
1028 static struct ctl_table brnf_table[] = {
1029         {
1030                 .procname       = "bridge-nf-call-arptables",
1031                 .data           = &brnf_call_arptables,
1032                 .maxlen         = sizeof(int),
1033                 .mode           = 0644,
1034                 .proc_handler   = brnf_sysctl_call_tables,
1035         },
1036         {
1037                 .procname       = "bridge-nf-call-iptables",
1038                 .data           = &brnf_call_iptables,
1039                 .maxlen         = sizeof(int),
1040                 .mode           = 0644,
1041                 .proc_handler   = brnf_sysctl_call_tables,
1042         },
1043         {
1044                 .procname       = "bridge-nf-call-ip6tables",
1045                 .data           = &brnf_call_ip6tables,
1046                 .maxlen         = sizeof(int),
1047                 .mode           = 0644,
1048                 .proc_handler   = brnf_sysctl_call_tables,
1049         },
1050         {
1051                 .procname       = "bridge-nf-filter-vlan-tagged",
1052                 .data           = &brnf_filter_vlan_tagged,
1053                 .maxlen         = sizeof(int),
1054                 .mode           = 0644,
1055                 .proc_handler   = brnf_sysctl_call_tables,
1056         },
1057         {
1058                 .procname       = "bridge-nf-filter-pppoe-tagged",
1059                 .data           = &brnf_filter_pppoe_tagged,
1060                 .maxlen         = sizeof(int),
1061                 .mode           = 0644,
1062                 .proc_handler   = brnf_sysctl_call_tables,
1063         },
1064         {
1065                 .procname       = "bridge-nf-pass-vlan-input-dev",
1066                 .data           = &brnf_pass_vlan_indev,
1067                 .maxlen         = sizeof(int),
1068                 .mode           = 0644,
1069                 .proc_handler   = brnf_sysctl_call_tables,
1070         },
1071         { }
1072 };
1073 #endif
1074
1075 static int __init br_netfilter_init(void)
1076 {
1077         int ret;
1078
1079         ret = register_pernet_subsys(&brnf_net_ops);
1080         if (ret < 0)
1081                 return ret;
1082
1083         ret = register_netdevice_notifier(&brnf_notifier);
1084         if (ret < 0) {
1085                 unregister_pernet_subsys(&brnf_net_ops);
1086                 return ret;
1087         }
1088
1089 #ifdef CONFIG_SYSCTL
1090         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1091         if (brnf_sysctl_header == NULL) {
1092                 printk(KERN_WARNING
1093                        "br_netfilter: can't register to sysctl.\n");
1094                 unregister_netdevice_notifier(&brnf_notifier);
1095                 unregister_pernet_subsys(&brnf_net_ops);
1096                 return -ENOMEM;
1097         }
1098 #endif
1099         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1100         printk(KERN_NOTICE "Bridge firewalling registered\n");
1101         return 0;
1102 }
1103
1104 static void __exit br_netfilter_fini(void)
1105 {
1106         RCU_INIT_POINTER(nf_br_ops, NULL);
1107         unregister_netdevice_notifier(&brnf_notifier);
1108         unregister_pernet_subsys(&brnf_net_ops);
1109 #ifdef CONFIG_SYSCTL
1110         unregister_net_sysctl_table(brnf_sysctl_header);
1111 #endif
1112 }
1113
1114 module_init(br_netfilter_init);
1115 module_exit(br_netfilter_fini);
1116
1117 MODULE_LICENSE("GPL");
1118 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1119 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1120 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");