linux/net/bridge/br_netfilter.c
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   1/*
   2 *      Handle firewalling
   3 *      Linux ethernet bridge
   4 *
   5 *      Authors:
   6 *      Lennert Buytenhek               <buytenh@gnu.org>
   7 *      Bart De Schuymer                <bdschuym@pandora.be>
   8 *
   9 *      This program is free software; you can redistribute it and/or
  10 *      modify it under the terms of the GNU General Public License
  11 *      as published by the Free Software Foundation; either version
  12 *      2 of the License, or (at your option) any later version.
  13 *
  14 *      Lennert dedicates this file to Kerstin Wurdinger.
  15 */
  16
  17#include <linux/module.h>
  18#include <linux/kernel.h>
  19#include <linux/slab.h>
  20#include <linux/ip.h>
  21#include <linux/netdevice.h>
  22#include <linux/skbuff.h>
  23#include <linux/if_arp.h>
  24#include <linux/if_ether.h>
  25#include <linux/if_vlan.h>
  26#include <linux/if_pppox.h>
  27#include <linux/ppp_defs.h>
  28#include <linux/netfilter_bridge.h>
  29#include <linux/netfilter_ipv4.h>
  30#include <linux/netfilter_ipv6.h>
  31#include <linux/netfilter_arp.h>
  32#include <linux/in_route.h>
  33#include <linux/inetdevice.h>
  34
  35#include <net/ip.h>
  36#include <net/ipv6.h>
  37#include <net/route.h>
  38
  39#include <asm/uaccess.h>
  40#include "br_private.h"
  41#ifdef CONFIG_SYSCTL
  42#include <linux/sysctl.h>
  43#endif
  44
  45#define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
  46                                 (skb->nf_bridge->data))->daddr.ipv4)
  47#define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
  48#define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
  49
  50#ifdef CONFIG_SYSCTL
  51static struct ctl_table_header *brnf_sysctl_header;
  52static int brnf_call_iptables __read_mostly = 1;
  53static int brnf_call_ip6tables __read_mostly = 1;
  54static int brnf_call_arptables __read_mostly = 1;
  55static int brnf_filter_vlan_tagged __read_mostly = 0;
  56static int brnf_filter_pppoe_tagged __read_mostly = 0;
  57static int brnf_pass_vlan_indev __read_mostly = 0;
  58#else
  59#define brnf_call_iptables 1
  60#define brnf_call_ip6tables 1
  61#define brnf_call_arptables 1
  62#define brnf_filter_vlan_tagged 0
  63#define brnf_filter_pppoe_tagged 0
  64#define brnf_pass_vlan_indev 0
  65#endif
  66
  67#define IS_IP(skb) \
  68        (!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
  69
  70#define IS_IPV6(skb) \
  71        (!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
  72
  73#define IS_ARP(skb) \
  74        (!vlan_tx_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
  75
  76static inline __be16 vlan_proto(const struct sk_buff *skb)
  77{
  78        if (vlan_tx_tag_present(skb))
  79                return skb->protocol;
  80        else if (skb->protocol == htons(ETH_P_8021Q))
  81                return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
  82        else
  83                return 0;
  84}
  85
  86#define IS_VLAN_IP(skb) \
  87        (vlan_proto(skb) == htons(ETH_P_IP) && \
  88         brnf_filter_vlan_tagged)
  89
  90#define IS_VLAN_IPV6(skb) \
  91        (vlan_proto(skb) == htons(ETH_P_IPV6) && \
  92         brnf_filter_vlan_tagged)
  93
  94#define IS_VLAN_ARP(skb) \
  95        (vlan_proto(skb) == htons(ETH_P_ARP) && \
  96         brnf_filter_vlan_tagged)
  97
  98static inline __be16 pppoe_proto(const struct sk_buff *skb)
  99{
 100        return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
 101                            sizeof(struct pppoe_hdr)));
 102}
 103
 104#define IS_PPPOE_IP(skb) \
 105        (skb->protocol == htons(ETH_P_PPP_SES) && \
 106         pppoe_proto(skb) == htons(PPP_IP) && \
 107         brnf_filter_pppoe_tagged)
 108
 109#define IS_PPPOE_IPV6(skb) \
 110        (skb->protocol == htons(ETH_P_PPP_SES) && \
 111         pppoe_proto(skb) == htons(PPP_IPV6) && \
 112         brnf_filter_pppoe_tagged)
 113
 114static void fake_update_pmtu(struct dst_entry *dst, struct sock *sk,
 115                             struct sk_buff *skb, u32 mtu)
 116{
 117}
 118
 119static void fake_redirect(struct dst_entry *dst, struct sock *sk,
 120                          struct sk_buff *skb)
 121{
 122}
 123
 124static u32 *fake_cow_metrics(struct dst_entry *dst, unsigned long old)
 125{
 126        return NULL;
 127}
 128
 129static struct neighbour *fake_neigh_lookup(const struct dst_entry *dst,
 130                                           struct sk_buff *skb,
 131                                           const void *daddr)
 132{
 133        return NULL;
 134}
 135
 136static unsigned int fake_mtu(const struct dst_entry *dst)
 137{
 138        return dst->dev->mtu;
 139}
 140
 141static struct dst_ops fake_dst_ops = {
 142        .family =               AF_INET,
 143        .protocol =             cpu_to_be16(ETH_P_IP),
 144        .update_pmtu =          fake_update_pmtu,
 145        .redirect =             fake_redirect,
 146        .cow_metrics =          fake_cow_metrics,
 147        .neigh_lookup =         fake_neigh_lookup,
 148        .mtu =                  fake_mtu,
 149};
 150
 151/*
 152 * Initialize bogus route table used to keep netfilter happy.
 153 * Currently, we fill in the PMTU entry because netfilter
 154 * refragmentation needs it, and the rt_flags entry because
 155 * ipt_REJECT needs it.  Future netfilter modules might
 156 * require us to fill additional fields.
 157 */
 158static const u32 br_dst_default_metrics[RTAX_MAX] = {
 159        [RTAX_MTU - 1] = 1500,
 160};
 161
 162void br_netfilter_rtable_init(struct net_bridge *br)
 163{
 164        struct rtable *rt = &br->fake_rtable;
 165
 166        atomic_set(&rt->dst.__refcnt, 1);
 167        rt->dst.dev = br->dev;
 168        rt->dst.path = &rt->dst;
 169        dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
 170        rt->dst.flags   = DST_NOXFRM | DST_NOPEER | DST_FAKE_RTABLE;
 171        rt->dst.ops = &fake_dst_ops;
 172}
 173
 174static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
 175{
 176        struct net_bridge_port *port;
 177
 178        port = br_port_get_rcu(dev);
 179        return port ? &port->br->fake_rtable : NULL;
 180}
 181
 182static inline struct net_device *bridge_parent(const struct net_device *dev)
 183{
 184        struct net_bridge_port *port;
 185
 186        port = br_port_get_rcu(dev);
 187        return port ? port->br->dev : NULL;
 188}
 189
 190static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
 191{
 192        skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 193        if (likely(skb->nf_bridge))
 194                atomic_set(&(skb->nf_bridge->use), 1);
 195
 196        return skb->nf_bridge;
 197}
 198
 199static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 200{
 201        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 202
 203        if (atomic_read(&nf_bridge->use) > 1) {
 204                struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 205
 206                if (tmp) {
 207                        memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
 208                        atomic_set(&tmp->use, 1);
 209                }
 210                nf_bridge_put(nf_bridge);
 211                nf_bridge = tmp;
 212        }
 213        return nf_bridge;
 214}
 215
 216static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
 217{
 218        unsigned int len = nf_bridge_encap_header_len(skb);
 219
 220        skb_push(skb, len);
 221        skb->network_header -= len;
 222}
 223
 224static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
 225{
 226        unsigned int len = nf_bridge_encap_header_len(skb);
 227
 228        skb_pull(skb, len);
 229        skb->network_header += len;
 230}
 231
 232static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
 233{
 234        unsigned int len = nf_bridge_encap_header_len(skb);
 235
 236        skb_pull_rcsum(skb, len);
 237        skb->network_header += len;
 238}
 239
 240static inline void nf_bridge_save_header(struct sk_buff *skb)
 241{
 242        int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 243
 244        skb_copy_from_linear_data_offset(skb, -header_size,
 245                                         skb->nf_bridge->data, header_size);
 246}
 247
 248static inline void nf_bridge_update_protocol(struct sk_buff *skb)
 249{
 250        if (skb->nf_bridge->mask & BRNF_8021Q)
 251                skb->protocol = htons(ETH_P_8021Q);
 252        else if (skb->nf_bridge->mask & BRNF_PPPoE)
 253                skb->protocol = htons(ETH_P_PPP_SES);
 254}
 255
 256/* When handing a packet over to the IP layer
 257 * check whether we have a skb that is in the
 258 * expected format
 259 */
 260
 261static int br_parse_ip_options(struct sk_buff *skb)
 262{
 263        struct ip_options *opt;
 264        const struct iphdr *iph;
 265        struct net_device *dev = skb->dev;
 266        u32 len;
 267
 268        iph = ip_hdr(skb);
 269        opt = &(IPCB(skb)->opt);
 270
 271        /* Basic sanity checks */
 272        if (iph->ihl < 5 || iph->version != 4)
 273                goto inhdr_error;
 274
 275        if (!pskb_may_pull(skb, iph->ihl*4))
 276                goto inhdr_error;
 277
 278        iph = ip_hdr(skb);
 279        if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
 280                goto inhdr_error;
 281
 282        len = ntohs(iph->tot_len);
 283        if (skb->len < len) {
 284                IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
 285                goto drop;
 286        } else if (len < (iph->ihl*4))
 287                goto inhdr_error;
 288
 289        if (pskb_trim_rcsum(skb, len)) {
 290                IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 291                goto drop;
 292        }
 293
 294        memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 295        if (iph->ihl == 5)
 296                return 0;
 297
 298        opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
 299        if (ip_options_compile(dev_net(dev), opt, skb))
 300                goto inhdr_error;
 301
 302        /* Check correct handling of SRR option */
 303        if (unlikely(opt->srr)) {
 304                struct in_device *in_dev = __in_dev_get_rcu(dev);
 305                if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
 306                        goto drop;
 307
 308                if (ip_options_rcv_srr(skb))
 309                        goto drop;
 310        }
 311
 312        return 0;
 313
 314inhdr_error:
 315        IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
 316drop:
 317        return -1;
 318}
 319
 320/* Fill in the header for fragmented IP packets handled by
 321 * the IPv4 connection tracking code.
 322 */
 323int nf_bridge_copy_header(struct sk_buff *skb)
 324{
 325        int err;
 326        unsigned int header_size;
 327
 328        nf_bridge_update_protocol(skb);
 329        header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
 330        err = skb_cow_head(skb, header_size);
 331        if (err)
 332                return err;
 333
 334        skb_copy_to_linear_data_offset(skb, -header_size,
 335                                       skb->nf_bridge->data, header_size);
 336        __skb_push(skb, nf_bridge_encap_header_len(skb));
 337        return 0;
 338}
 339
 340/* PF_BRIDGE/PRE_ROUTING *********************************************/
 341/* Undo the changes made for ip6tables PREROUTING and continue the
 342 * bridge PRE_ROUTING hook. */
 343static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
 344{
 345        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 346        struct rtable *rt;
 347
 348        if (nf_bridge->mask & BRNF_PKT_TYPE) {
 349                skb->pkt_type = PACKET_OTHERHOST;
 350                nf_bridge->mask ^= BRNF_PKT_TYPE;
 351        }
 352        nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 353
 354        rt = bridge_parent_rtable(nf_bridge->physindev);
 355        if (!rt) {
 356                kfree_skb(skb);
 357                return 0;
 358        }
 359        skb_dst_set_noref(skb, &rt->dst);
 360
 361        skb->dev = nf_bridge->physindev;
 362        nf_bridge_update_protocol(skb);
 363        nf_bridge_push_encap_header(skb);
 364        NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 365                       br_handle_frame_finish, 1);
 366
 367        return 0;
 368}
 369
 370/* Obtain the correct destination MAC address, while preserving the original
 371 * source MAC address. If we already know this address, we just copy it. If we
 372 * don't, we use the neighbour framework to find out. In both cases, we make
 373 * sure that br_handle_frame_finish() is called afterwards.
 374 */
 375static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
 376{
 377        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 378        struct neighbour *neigh;
 379        struct dst_entry *dst;
 380
 381        skb->dev = bridge_parent(skb->dev);
 382        if (!skb->dev)
 383                goto free_skb;
 384        dst = skb_dst(skb);
 385        neigh = dst_neigh_lookup_skb(dst, skb);
 386        if (neigh) {
 387                int ret;
 388
 389                if (neigh->hh.hh_len) {
 390                        neigh_hh_bridge(&neigh->hh, skb);
 391                        skb->dev = nf_bridge->physindev;
 392                        ret = br_handle_frame_finish(skb);
 393                } else {
 394                        /* the neighbour function below overwrites the complete
 395                         * MAC header, so we save the Ethernet source address and
 396                         * protocol number.
 397                         */
 398                        skb_copy_from_linear_data_offset(skb,
 399                                                         -(ETH_HLEN-ETH_ALEN),
 400                                                         skb->nf_bridge->data,
 401                                                         ETH_HLEN-ETH_ALEN);
 402                        /* tell br_dev_xmit to continue with forwarding */
 403                        nf_bridge->mask |= BRNF_BRIDGED_DNAT;
 404                        ret = neigh->output(neigh, skb);
 405                }
 406                neigh_release(neigh);
 407                return ret;
 408        }
 409free_skb:
 410        kfree_skb(skb);
 411        return 0;
 412}
 413
 414/* This requires some explaining. If DNAT has taken place,
 415 * we will need to fix up the destination Ethernet address.
 416 *
 417 * There are two cases to consider:
 418 * 1. The packet was DNAT'ed to a device in the same bridge
 419 *    port group as it was received on. We can still bridge
 420 *    the packet.
 421 * 2. The packet was DNAT'ed to a different device, either
 422 *    a non-bridged device or another bridge port group.
 423 *    The packet will need to be routed.
 424 *
 425 * The correct way of distinguishing between these two cases is to
 426 * call ip_route_input() and to look at skb->dst->dev, which is
 427 * changed to the destination device if ip_route_input() succeeds.
 428 *
 429 * Let's first consider the case that ip_route_input() succeeds:
 430 *
 431 * If the output device equals the logical bridge device the packet
 432 * came in on, we can consider this bridging. The corresponding MAC
 433 * address will be obtained in br_nf_pre_routing_finish_bridge.
 434 * Otherwise, the packet is considered to be routed and we just
 435 * change the destination MAC address so that the packet will
 436 * later be passed up to the IP stack to be routed. For a redirected
 437 * packet, ip_route_input() will give back the localhost as output device,
 438 * which differs from the bridge device.
 439 *
 440 * Let's now consider the case that ip_route_input() fails:
 441 *
 442 * This can be because the destination address is martian, in which case
 443 * the packet will be dropped.
 444 * If IP forwarding is disabled, ip_route_input() will fail, while
 445 * ip_route_output_key() can return success. The source
 446 * address for ip_route_output_key() is set to zero, so ip_route_output_key()
 447 * thinks we're handling a locally generated packet and won't care
 448 * if IP forwarding is enabled. If the output device equals the logical bridge
 449 * device, we proceed as if ip_route_input() succeeded. If it differs from the
 450 * logical bridge port or if ip_route_output_key() fails we drop the packet.
 451 */
 452static int br_nf_pre_routing_finish(struct sk_buff *skb)
 453{
 454        struct net_device *dev = skb->dev;
 455        struct iphdr *iph = ip_hdr(skb);
 456        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 457        struct rtable *rt;
 458        int err;
 459
 460        if (nf_bridge->mask & BRNF_PKT_TYPE) {
 461                skb->pkt_type = PACKET_OTHERHOST;
 462                nf_bridge->mask ^= BRNF_PKT_TYPE;
 463        }
 464        nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 465        if (dnat_took_place(skb)) {
 466                if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
 467                        struct in_device *in_dev = __in_dev_get_rcu(dev);
 468
 469                        /* If err equals -EHOSTUNREACH the error is due to a
 470                         * martian destination or due to the fact that
 471                         * forwarding is disabled. For most martian packets,
 472                         * ip_route_output_key() will fail. It won't fail for 2 types of
 473                         * martian destinations: loopback destinations and destination
 474                         * 0.0.0.0. In both cases the packet will be dropped because the
 475                         * destination is the loopback device and not the bridge. */
 476                        if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
 477                                goto free_skb;
 478
 479                        rt = ip_route_output(dev_net(dev), iph->daddr, 0,
 480                                             RT_TOS(iph->tos), 0);
 481                        if (!IS_ERR(rt)) {
 482                                /* - Bridged-and-DNAT'ed traffic doesn't
 483                                 *   require ip_forwarding. */
 484                                if (rt->dst.dev == dev) {
 485                                        skb_dst_set(skb, &rt->dst);
 486                                        goto bridged_dnat;
 487                                }
 488                                ip_rt_put(rt);
 489                        }
 490free_skb:
 491                        kfree_skb(skb);
 492                        return 0;
 493                } else {
 494                        if (skb_dst(skb)->dev == dev) {
 495bridged_dnat:
 496                                skb->dev = nf_bridge->physindev;
 497                                nf_bridge_update_protocol(skb);
 498                                nf_bridge_push_encap_header(skb);
 499                                NF_HOOK_THRESH(NFPROTO_BRIDGE,
 500                                               NF_BR_PRE_ROUTING,
 501                                               skb, skb->dev, NULL,
 502                                               br_nf_pre_routing_finish_bridge,
 503                                               1);
 504                                return 0;
 505                        }
 506                        memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
 507                        skb->pkt_type = PACKET_HOST;
 508                }
 509        } else {
 510                rt = bridge_parent_rtable(nf_bridge->physindev);
 511                if (!rt) {
 512                        kfree_skb(skb);
 513                        return 0;
 514                }
 515                skb_dst_set_noref(skb, &rt->dst);
 516        }
 517
 518        skb->dev = nf_bridge->physindev;
 519        nf_bridge_update_protocol(skb);
 520        nf_bridge_push_encap_header(skb);
 521        NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
 522                       br_handle_frame_finish, 1);
 523
 524        return 0;
 525}
 526
 527static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
 528{
 529        struct net_device *vlan, *br;
 530
 531        br = bridge_parent(dev);
 532        if (brnf_pass_vlan_indev == 0 || !vlan_tx_tag_present(skb))
 533                return br;
 534
 535        vlan = __vlan_find_dev_deep(br, vlan_tx_tag_get(skb) & VLAN_VID_MASK);
 536
 537        return vlan ? vlan : br;
 538}
 539
 540/* Some common code for IPv4/IPv6 */
 541static struct net_device *setup_pre_routing(struct sk_buff *skb)
 542{
 543        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 544
 545        if (skb->pkt_type == PACKET_OTHERHOST) {
 546                skb->pkt_type = PACKET_HOST;
 547                nf_bridge->mask |= BRNF_PKT_TYPE;
 548        }
 549
 550        nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
 551        nf_bridge->physindev = skb->dev;
 552        skb->dev = brnf_get_logical_dev(skb, skb->dev);
 553        if (skb->protocol == htons(ETH_P_8021Q))
 554                nf_bridge->mask |= BRNF_8021Q;
 555        else if (skb->protocol == htons(ETH_P_PPP_SES))
 556                nf_bridge->mask |= BRNF_PPPoE;
 557
 558        return skb->dev;
 559}
 560
 561/* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
 562static int check_hbh_len(struct sk_buff *skb)
 563{
 564        unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
 565        u32 pkt_len;
 566        const unsigned char *nh = skb_network_header(skb);
 567        int off = raw - nh;
 568        int len = (raw[1] + 1) << 3;
 569
 570        if ((raw + len) - skb->data > skb_headlen(skb))
 571                goto bad;
 572
 573        off += 2;
 574        len -= 2;
 575
 576        while (len > 0) {
 577                int optlen = nh[off + 1] + 2;
 578
 579                switch (nh[off]) {
 580                case IPV6_TLV_PAD1:
 581                        optlen = 1;
 582                        break;
 583
 584                case IPV6_TLV_PADN:
 585                        break;
 586
 587                case IPV6_TLV_JUMBO:
 588                        if (nh[off + 1] != 4 || (off & 3) != 2)
 589                                goto bad;
 590                        pkt_len = ntohl(*(__be32 *) (nh + off + 2));
 591                        if (pkt_len <= IPV6_MAXPLEN ||
 592                            ipv6_hdr(skb)->payload_len)
 593                                goto bad;
 594                        if (pkt_len > skb->len - sizeof(struct ipv6hdr))
 595                                goto bad;
 596                        if (pskb_trim_rcsum(skb,
 597                                            pkt_len + sizeof(struct ipv6hdr)))
 598                                goto bad;
 599                        nh = skb_network_header(skb);
 600                        break;
 601                default:
 602                        if (optlen > len)
 603                                goto bad;
 604                        break;
 605                }
 606                off += optlen;
 607                len -= optlen;
 608        }
 609        if (len == 0)
 610                return 0;
 611bad:
 612        return -1;
 613
 614}
 615
 616/* Replicate the checks that IPv6 does on packet reception and pass the packet
 617 * to ip6tables, which doesn't support NAT, so things are fairly simple. */
 618static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
 619                                           struct sk_buff *skb,
 620                                           const struct net_device *in,
 621                                           const struct net_device *out,
 622                                           int (*okfn)(struct sk_buff *))
 623{
 624        const struct ipv6hdr *hdr;
 625        u32 pkt_len;
 626
 627        if (skb->len < sizeof(struct ipv6hdr))
 628                return NF_DROP;
 629
 630        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 631                return NF_DROP;
 632
 633        hdr = ipv6_hdr(skb);
 634
 635        if (hdr->version != 6)
 636                return NF_DROP;
 637
 638        pkt_len = ntohs(hdr->payload_len);
 639
 640        if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 641                if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
 642                        return NF_DROP;
 643                if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
 644                        return NF_DROP;
 645        }
 646        if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
 647                return NF_DROP;
 648
 649        nf_bridge_put(skb->nf_bridge);
 650        if (!nf_bridge_alloc(skb))
 651                return NF_DROP;
 652        if (!setup_pre_routing(skb))
 653                return NF_DROP;
 654
 655        skb->protocol = htons(ETH_P_IPV6);
 656        NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 657                br_nf_pre_routing_finish_ipv6);
 658
 659        return NF_STOLEN;
 660}
 661
 662/* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
 663 * Replicate the checks that IPv4 does on packet reception.
 664 * Set skb->dev to the bridge device (i.e. parent of the
 665 * receiving device) to make netfilter happy, the REDIRECT
 666 * target in particular.  Save the original destination IP
 667 * address to be able to detect DNAT afterwards. */
 668static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
 669                                      const struct net_device *in,
 670                                      const struct net_device *out,
 671                                      int (*okfn)(struct sk_buff *))
 672{
 673        struct net_bridge_port *p;
 674        struct net_bridge *br;
 675        __u32 len = nf_bridge_encap_header_len(skb);
 676
 677        if (unlikely(!pskb_may_pull(skb, len)))
 678                return NF_DROP;
 679
 680        p = br_port_get_rcu(in);
 681        if (p == NULL)
 682                return NF_DROP;
 683        br = p->br;
 684
 685        if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
 686                if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
 687                        return NF_ACCEPT;
 688
 689                nf_bridge_pull_encap_header_rcsum(skb);
 690                return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
 691        }
 692
 693        if (!brnf_call_iptables && !br->nf_call_iptables)
 694                return NF_ACCEPT;
 695
 696        if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
 697                return NF_ACCEPT;
 698
 699        nf_bridge_pull_encap_header_rcsum(skb);
 700
 701        if (br_parse_ip_options(skb))
 702                return NF_DROP;
 703
 704        nf_bridge_put(skb->nf_bridge);
 705        if (!nf_bridge_alloc(skb))
 706                return NF_DROP;
 707        if (!setup_pre_routing(skb))
 708                return NF_DROP;
 709        store_orig_dstaddr(skb);
 710        skb->protocol = htons(ETH_P_IP);
 711
 712        NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 713                br_nf_pre_routing_finish);
 714
 715        return NF_STOLEN;
 716}
 717
 718
 719/* PF_BRIDGE/LOCAL_IN ************************************************/
 720/* The packet is locally destined, which requires a real
 721 * dst_entry, so detach the fake one.  On the way up, the
 722 * packet would pass through PRE_ROUTING again (which already
 723 * took place when the packet entered the bridge), but we
 724 * register an IPv4 PRE_ROUTING 'sabotage' hook that will
 725 * prevent this from happening. */
 726static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
 727                                   const struct net_device *in,
 728                                   const struct net_device *out,
 729                                   int (*okfn)(struct sk_buff *))
 730{
 731        br_drop_fake_rtable(skb);
 732        return NF_ACCEPT;
 733}
 734
 735/* PF_BRIDGE/FORWARD *************************************************/
 736static int br_nf_forward_finish(struct sk_buff *skb)
 737{
 738        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 739        struct net_device *in;
 740
 741        if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
 742                in = nf_bridge->physindev;
 743                if (nf_bridge->mask & BRNF_PKT_TYPE) {
 744                        skb->pkt_type = PACKET_OTHERHOST;
 745                        nf_bridge->mask ^= BRNF_PKT_TYPE;
 746                }
 747                nf_bridge_update_protocol(skb);
 748        } else {
 749                in = *((struct net_device **)(skb->cb));
 750        }
 751        nf_bridge_push_encap_header(skb);
 752
 753        NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
 754                       skb->dev, br_forward_finish, 1);
 755        return 0;
 756}
 757
 758
 759/* This is the 'purely bridged' case.  For IP, we pass the packet to
 760 * netfilter with indev and outdev set to the bridge device,
 761 * but we are still able to filter on the 'real' indev/outdev
 762 * because of the physdev module. For ARP, indev and outdev are the
 763 * bridge ports. */
 764static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
 765                                     const struct net_device *in,
 766                                     const struct net_device *out,
 767                                     int (*okfn)(struct sk_buff *))
 768{
 769        struct nf_bridge_info *nf_bridge;
 770        struct net_device *parent;
 771        u_int8_t pf;
 772
 773        if (!skb->nf_bridge)
 774                return NF_ACCEPT;
 775
 776        /* Need exclusive nf_bridge_info since we might have multiple
 777         * different physoutdevs. */
 778        if (!nf_bridge_unshare(skb))
 779                return NF_DROP;
 780
 781        parent = bridge_parent(out);
 782        if (!parent)
 783                return NF_DROP;
 784
 785        if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 786                pf = NFPROTO_IPV4;
 787        else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 788                pf = NFPROTO_IPV6;
 789        else
 790                return NF_ACCEPT;
 791
 792        nf_bridge_pull_encap_header(skb);
 793
 794        nf_bridge = skb->nf_bridge;
 795        if (skb->pkt_type == PACKET_OTHERHOST) {
 796                skb->pkt_type = PACKET_HOST;
 797                nf_bridge->mask |= BRNF_PKT_TYPE;
 798        }
 799
 800        if (pf == NFPROTO_IPV4 && br_parse_ip_options(skb))
 801                return NF_DROP;
 802
 803        /* The physdev module checks on this */
 804        nf_bridge->mask |= BRNF_BRIDGED;
 805        nf_bridge->physoutdev = skb->dev;
 806        if (pf == NFPROTO_IPV4)
 807                skb->protocol = htons(ETH_P_IP);
 808        else
 809                skb->protocol = htons(ETH_P_IPV6);
 810
 811        NF_HOOK(pf, NF_INET_FORWARD, skb, brnf_get_logical_dev(skb, in), parent,
 812                br_nf_forward_finish);
 813
 814        return NF_STOLEN;
 815}
 816
 817static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
 818                                      const struct net_device *in,
 819                                      const struct net_device *out,
 820                                      int (*okfn)(struct sk_buff *))
 821{
 822        struct net_bridge_port *p;
 823        struct net_bridge *br;
 824        struct net_device **d = (struct net_device **)(skb->cb);
 825
 826        p = br_port_get_rcu(out);
 827        if (p == NULL)
 828                return NF_ACCEPT;
 829        br = p->br;
 830
 831        if (!brnf_call_arptables && !br->nf_call_arptables)
 832                return NF_ACCEPT;
 833
 834        if (!IS_ARP(skb)) {
 835                if (!IS_VLAN_ARP(skb))
 836                        return NF_ACCEPT;
 837                nf_bridge_pull_encap_header(skb);
 838        }
 839
 840        if (arp_hdr(skb)->ar_pln != 4) {
 841                if (IS_VLAN_ARP(skb))
 842                        nf_bridge_push_encap_header(skb);
 843                return NF_ACCEPT;
 844        }
 845        *d = (struct net_device *)in;
 846        NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
 847                (struct net_device *)out, br_nf_forward_finish);
 848
 849        return NF_STOLEN;
 850}
 851
 852#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV4)
 853static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 854{
 855        int ret;
 856
 857        if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
 858            skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
 859            !skb_is_gso(skb)) {
 860                if (br_parse_ip_options(skb))
 861                        /* Drop invalid packet */
 862                        return NF_DROP;
 863                ret = ip_fragment(skb, br_dev_queue_push_xmit);
 864        } else
 865                ret = br_dev_queue_push_xmit(skb);
 866
 867        return ret;
 868}
 869#else
 870static int br_nf_dev_queue_xmit(struct sk_buff *skb)
 871{
 872        return br_dev_queue_push_xmit(skb);
 873}
 874#endif
 875
 876/* PF_BRIDGE/POST_ROUTING ********************************************/
 877static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
 878                                       const struct net_device *in,
 879                                       const struct net_device *out,
 880                                       int (*okfn)(struct sk_buff *))
 881{
 882        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 883        struct net_device *realoutdev = bridge_parent(skb->dev);
 884        u_int8_t pf;
 885
 886        if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
 887                return NF_ACCEPT;
 888
 889        if (!realoutdev)
 890                return NF_DROP;
 891
 892        if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
 893                pf = NFPROTO_IPV4;
 894        else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
 895                pf = NFPROTO_IPV6;
 896        else
 897                return NF_ACCEPT;
 898
 899        /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
 900         * about the value of skb->pkt_type. */
 901        if (skb->pkt_type == PACKET_OTHERHOST) {
 902                skb->pkt_type = PACKET_HOST;
 903                nf_bridge->mask |= BRNF_PKT_TYPE;
 904        }
 905
 906        nf_bridge_pull_encap_header(skb);
 907        nf_bridge_save_header(skb);
 908        if (pf == NFPROTO_IPV4)
 909                skb->protocol = htons(ETH_P_IP);
 910        else
 911                skb->protocol = htons(ETH_P_IPV6);
 912
 913        NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
 914                br_nf_dev_queue_xmit);
 915
 916        return NF_STOLEN;
 917}
 918
 919/* IP/SABOTAGE *****************************************************/
 920/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
 921 * for the second time. */
 922static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
 923                                   const struct net_device *in,
 924                                   const struct net_device *out,
 925                                   int (*okfn)(struct sk_buff *))
 926{
 927        if (skb->nf_bridge &&
 928            !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
 929                return NF_STOP;
 930        }
 931
 932        return NF_ACCEPT;
 933}
 934
 935/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
 936 * br_dev_queue_push_xmit is called afterwards */
 937static struct nf_hook_ops br_nf_ops[] __read_mostly = {
 938        {
 939                .hook = br_nf_pre_routing,
 940                .owner = THIS_MODULE,
 941                .pf = NFPROTO_BRIDGE,
 942                .hooknum = NF_BR_PRE_ROUTING,
 943                .priority = NF_BR_PRI_BRNF,
 944        },
 945        {
 946                .hook = br_nf_local_in,
 947                .owner = THIS_MODULE,
 948                .pf = NFPROTO_BRIDGE,
 949                .hooknum = NF_BR_LOCAL_IN,
 950                .priority = NF_BR_PRI_BRNF,
 951        },
 952        {
 953                .hook = br_nf_forward_ip,
 954                .owner = THIS_MODULE,
 955                .pf = NFPROTO_BRIDGE,
 956                .hooknum = NF_BR_FORWARD,
 957                .priority = NF_BR_PRI_BRNF - 1,
 958        },
 959        {
 960                .hook = br_nf_forward_arp,
 961                .owner = THIS_MODULE,
 962                .pf = NFPROTO_BRIDGE,
 963                .hooknum = NF_BR_FORWARD,
 964                .priority = NF_BR_PRI_BRNF,
 965        },
 966        {
 967                .hook = br_nf_post_routing,
 968                .owner = THIS_MODULE,
 969                .pf = NFPROTO_BRIDGE,
 970                .hooknum = NF_BR_POST_ROUTING,
 971                .priority = NF_BR_PRI_LAST,
 972        },
 973        {
 974                .hook = ip_sabotage_in,
 975                .owner = THIS_MODULE,
 976                .pf = NFPROTO_IPV4,
 977                .hooknum = NF_INET_PRE_ROUTING,
 978                .priority = NF_IP_PRI_FIRST,
 979        },
 980        {
 981                .hook = ip_sabotage_in,
 982                .owner = THIS_MODULE,
 983                .pf = NFPROTO_IPV6,
 984                .hooknum = NF_INET_PRE_ROUTING,
 985                .priority = NF_IP6_PRI_FIRST,
 986        },
 987};
 988
 989#ifdef CONFIG_SYSCTL
 990static
 991int brnf_sysctl_call_tables(ctl_table * ctl, int write,
 992                            void __user * buffer, size_t * lenp, loff_t * ppos)
 993{
 994        int ret;
 995
 996        ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
 997
 998        if (write && *(int *)(ctl->data))
 999                *(int *)(ctl->data) = 1;
1000        return ret;
1001}
1002
1003static ctl_table brnf_table[] = {
1004        {
1005                .procname       = "bridge-nf-call-arptables",
1006                .data           = &brnf_call_arptables,
1007                .maxlen         = sizeof(int),
1008                .mode           = 0644,
1009                .proc_handler   = brnf_sysctl_call_tables,
1010        },
1011        {
1012                .procname       = "bridge-nf-call-iptables",
1013                .data           = &brnf_call_iptables,
1014                .maxlen         = sizeof(int),
1015                .mode           = 0644,
1016                .proc_handler   = brnf_sysctl_call_tables,
1017        },
1018        {
1019                .procname       = "bridge-nf-call-ip6tables",
1020                .data           = &brnf_call_ip6tables,
1021                .maxlen         = sizeof(int),
1022                .mode           = 0644,
1023                .proc_handler   = brnf_sysctl_call_tables,
1024        },
1025        {
1026                .procname       = "bridge-nf-filter-vlan-tagged",
1027                .data           = &brnf_filter_vlan_tagged,
1028                .maxlen         = sizeof(int),
1029                .mode           = 0644,
1030                .proc_handler   = brnf_sysctl_call_tables,
1031        },
1032        {
1033                .procname       = "bridge-nf-filter-pppoe-tagged",
1034                .data           = &brnf_filter_pppoe_tagged,
1035                .maxlen         = sizeof(int),
1036                .mode           = 0644,
1037                .proc_handler   = brnf_sysctl_call_tables,
1038        },
1039        {
1040                .procname       = "bridge-nf-pass-vlan-input-dev",
1041                .data           = &brnf_pass_vlan_indev,
1042                .maxlen         = sizeof(int),
1043                .mode           = 0644,
1044                .proc_handler   = brnf_sysctl_call_tables,
1045        },
1046        { }
1047};
1048#endif
1049
1050int __init br_netfilter_init(void)
1051{
1052        int ret;
1053
1054        ret = dst_entries_init(&fake_dst_ops);
1055        if (ret < 0)
1056                return ret;
1057
1058        ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1059        if (ret < 0) {
1060                dst_entries_destroy(&fake_dst_ops);
1061                return ret;
1062        }
1063#ifdef CONFIG_SYSCTL
1064        brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1065        if (brnf_sysctl_header == NULL) {
1066                printk(KERN_WARNING
1067                       "br_netfilter: can't register to sysctl.\n");
1068                nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1069                dst_entries_destroy(&fake_dst_ops);
1070                return -ENOMEM;
1071        }
1072#endif
1073        printk(KERN_NOTICE "Bridge firewalling registered\n");
1074        return 0;
1075}
1076
1077void br_netfilter_fini(void)
1078{
1079        nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1080#ifdef CONFIG_SYSCTL
1081        unregister_net_sysctl_table(brnf_sysctl_header);
1082#endif
1083        dst_entries_destroy(&fake_dst_ops);
1084}
1085
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