3 * Linux ethernet bridge
6 * Lennert Buytenhek <buytenh@gnu.org>
7 * Bart De Schuymer <bdschuym@pandora.be>
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.
14 * Lennert dedicates this file to Kerstin Wurdinger.
17 #include <linux/module.h>
18 #include <linux/kernel.h>
19 #include <linux/slab.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>
39 #include <net/addrconf.h>
40 #include <net/route.h>
41 #include <net/netfilter/br_netfilter.h>
42 #include <net/netns/generic.h>
44 #include <linux/uaccess.h>
45 #include "br_private.h"
47 #include <linux/sysctl.h>
50 static unsigned int brnf_net_id __read_mostly;
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;
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
74 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
76 #define IS_IPV6(skb) \
77 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
80 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
82 static inline __be16 vlan_proto(const struct sk_buff *skb)
84 if (skb_vlan_tag_present(skb))
86 else if (skb->protocol == htons(ETH_P_8021Q))
87 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
92 #define IS_VLAN_IP(skb) \
93 (vlan_proto(skb) == htons(ETH_P_IP) && \
94 brnf_filter_vlan_tagged)
96 #define IS_VLAN_IPV6(skb) \
97 (vlan_proto(skb) == htons(ETH_P_IPV6) && \
98 brnf_filter_vlan_tagged)
100 #define IS_VLAN_ARP(skb) \
101 (vlan_proto(skb) == htons(ETH_P_ARP) && \
102 brnf_filter_vlan_tagged)
104 static inline __be16 pppoe_proto(const struct sk_buff *skb)
106 return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
107 sizeof(struct pppoe_hdr)));
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)
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)
120 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
121 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
123 struct brnf_frag_data {
124 char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
131 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
133 static void nf_bridge_info_free(struct sk_buff *skb)
135 skb_ext_del(skb, SKB_EXT_BRIDGE_NF);
138 static inline struct net_device *bridge_parent(const struct net_device *dev)
140 struct net_bridge_port *port;
142 port = br_port_get_rcu(dev);
143 return port ? port->br->dev : NULL;
146 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
148 return skb_ext_add(skb, SKB_EXT_BRIDGE_NF);
151 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
153 switch (skb->protocol) {
154 case __cpu_to_be16(ETH_P_8021Q):
156 case __cpu_to_be16(ETH_P_PPP_SES):
157 return PPPOE_SES_HLEN;
163 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
165 unsigned int len = nf_bridge_encap_header_len(skb);
168 skb->network_header += len;
171 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
173 unsigned int len = nf_bridge_encap_header_len(skb);
175 skb_pull_rcsum(skb, len);
176 skb->network_header += len;
179 /* When handing a packet over to the IP layer
180 * check whether we have a skb that is in the
184 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
186 const struct iphdr *iph;
189 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
194 /* Basic sanity checks */
195 if (iph->ihl < 5 || iph->version != 4)
198 if (!pskb_may_pull(skb, iph->ihl*4))
202 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
205 len = ntohs(iph->tot_len);
206 if (skb->len < len) {
207 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
209 } else if (len < (iph->ihl*4))
212 if (pskb_trim_rcsum(skb, len)) {
213 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
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
226 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
228 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
233 void nf_bridge_update_protocol(struct sk_buff *skb)
235 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
237 switch (nf_bridge->orig_proto) {
238 case BRNF_PROTO_8021Q:
239 skb->protocol = htons(ETH_P_8021Q);
241 case BRNF_PROTO_PPPOE:
242 skb->protocol = htons(ETH_P_PPP_SES);
244 case BRNF_PROTO_UNCHANGED:
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.
254 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
256 struct neighbour *neigh;
257 struct dst_entry *dst;
259 skb->dev = bridge_parent(skb->dev);
263 neigh = dst_neigh_lookup_skb(dst, skb);
265 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
268 if (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);
273 /* the neighbour function below overwrites the complete
274 * MAC header, so we save the Ethernet source address and
277 skb_copy_from_linear_data_offset(skb,
278 -(ETH_HLEN-ETH_ALEN),
279 nf_bridge->neigh_header,
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);
286 neigh_release(neigh);
295 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
296 const struct nf_bridge_info *nf_bridge)
298 return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
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).
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
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.
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.
317 * Let's first consider the case that ip_route_input() succeeds:
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.
328 * Let's now consider the case that ip_route_input() fails:
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.
340 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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);
348 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
350 if (nf_bridge->pkt_otherhost) {
351 skb->pkt_type = PACKET_OTHERHOST;
352 nf_bridge->pkt_otherhost = false;
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);
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))
369 rt = ip_route_output(net, iph->daddr, 0,
370 RT_TOS(iph->tos), 0);
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);
384 if (skb_dst(skb)->dev == dev) {
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,
392 br_nf_pre_routing_finish_bridge);
395 ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
396 skb->pkt_type = PACKET_HOST;
399 rt = bridge_parent_rtable(nf_bridge->physindev);
404 skb_dst_set_noref(skb, &rt->dst);
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);
415 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
417 struct net_device *vlan, *br;
419 br = bridge_parent(dev);
420 if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
423 vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
424 skb_vlan_tag_get(skb) & VLAN_VID_MASK);
426 return vlan ? vlan : br;
429 /* Some common code for IPv4/IPv6 */
430 struct net_device *setup_pre_routing(struct sk_buff *skb)
432 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
434 if (skb->pkt_type == PACKET_OTHERHOST) {
435 skb->pkt_type = PACKET_HOST;
436 nf_bridge->pkt_otherhost = true;
439 nf_bridge->in_prerouting = 1;
440 nf_bridge->physindev = skb->dev;
441 skb->dev = brnf_get_logical_dev(skb, skb->dev);
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;
448 /* Must drop socket now because of tproxy. */
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,
461 const struct nf_hook_state *state)
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);
468 if (unlikely(!pskb_may_pull(skb, len)))
471 p = br_port_get_rcu(state->in);
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))
481 nf_bridge_pull_encap_header_rcsum(skb);
482 return br_nf_pre_routing_ipv6(priv, skb, state);
485 if (!brnf_call_iptables && !br_opt_get(br, BROPT_NF_CALL_IPTABLES))
488 if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
491 nf_bridge_pull_encap_header_rcsum(skb);
493 if (br_validate_ipv4(state->net, skb))
496 if (!nf_bridge_alloc(skb))
498 if (!setup_pre_routing(skb))
501 nf_bridge = nf_bridge_info_get(skb);
502 nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
504 skb->protocol = htons(ETH_P_IP);
506 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
508 br_nf_pre_routing_finish);
514 /* PF_BRIDGE/FORWARD *************************************************/
515 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
517 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
518 struct net_device *in;
520 if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
522 if (skb->protocol == htons(ETH_P_IP))
523 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
525 if (skb->protocol == htons(ETH_P_IPV6))
526 nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
528 in = nf_bridge->physindev;
529 if (nf_bridge->pkt_otherhost) {
530 skb->pkt_type = PACKET_OTHERHOST;
531 nf_bridge->pkt_otherhost = false;
533 nf_bridge_update_protocol(skb);
535 in = *((struct net_device **)(skb->cb));
537 nf_bridge_push_encap_header(skb);
539 br_nf_hook_thresh(NF_BR_FORWARD, net, sk, skb, in, skb->dev,
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
550 static unsigned int br_nf_forward_ip(void *priv,
552 const struct nf_hook_state *state)
554 struct nf_bridge_info *nf_bridge;
555 struct net_device *parent;
558 nf_bridge = nf_bridge_info_get(skb);
562 /* Need exclusive nf_bridge_info since we might have multiple
563 * different physoutdevs. */
564 if (!nf_bridge_unshare(skb))
567 nf_bridge = nf_bridge_info_get(skb);
571 parent = bridge_parent(state->out);
575 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
577 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
582 nf_bridge_pull_encap_header(skb);
584 if (skb->pkt_type == PACKET_OTHERHOST) {
585 skb->pkt_type = PACKET_HOST;
586 nf_bridge->pkt_otherhost = true;
589 if (pf == NFPROTO_IPV4) {
590 if (br_validate_ipv4(state->net, skb))
592 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
595 if (pf == NFPROTO_IPV6) {
596 if (br_validate_ipv6(state->net, skb))
598 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
601 nf_bridge->physoutdev = skb->dev;
602 if (pf == NFPROTO_IPV4)
603 skb->protocol = htons(ETH_P_IP);
605 skb->protocol = htons(ETH_P_IPV6);
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);
614 static unsigned int br_nf_forward_arp(void *priv,
616 const struct nf_hook_state *state)
618 struct net_bridge_port *p;
619 struct net_bridge *br;
620 struct net_device **d = (struct net_device **)(skb->cb);
622 p = br_port_get_rcu(state->out);
627 if (!brnf_call_arptables && !br_opt_get(br, BROPT_NF_CALL_ARPTABLES))
631 if (!IS_VLAN_ARP(skb))
633 nf_bridge_pull_encap_header(skb);
636 if (arp_hdr(skb)->ar_pln != 4) {
637 if (IS_VLAN_ARP(skb))
638 nf_bridge_push_encap_header(skb);
642 NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
643 state->in, state->out, br_nf_forward_finish);
648 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
650 struct brnf_frag_data *data;
653 data = this_cpu_ptr(&brnf_frag_data_storage);
654 err = skb_cow_head(skb, data->size);
661 if (data->vlan_proto)
662 __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
664 skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
665 __skb_push(skb, data->encap_size);
667 nf_bridge_info_free(skb);
668 return br_dev_queue_push_xmit(net, sk, skb);
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 *))
675 unsigned int mtu = ip_skb_dst_mtu(sk, skb);
676 struct iphdr *iph = ip_hdr(skb);
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);
686 return ip_do_fragment(net, sk, skb, output);
689 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
691 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
693 if (nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
694 return PPPOE_SES_HLEN;
698 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
700 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
701 unsigned int mtu, mtu_reserved;
703 mtu_reserved = nf_bridge_mtu_reduction(skb);
706 if (nf_bridge->frag_max_size && nf_bridge->frag_max_size < mtu)
707 mtu = nf_bridge->frag_max_size;
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);
714 /* This is wrong! We should preserve the original fragment
715 * boundaries by preserving frag_list rather than refragmenting.
717 if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
718 skb->protocol == htons(ETH_P_IP)) {
719 struct brnf_frag_data *data;
721 if (br_validate_ipv4(net, skb))
724 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
726 nf_bridge_update_protocol(skb);
728 data = this_cpu_ptr(&brnf_frag_data_storage);
730 if (skb_vlan_tag_present(skb)) {
731 data->vlan_tci = skb->vlan_tci;
732 data->vlan_proto = skb->vlan_proto;
734 data->vlan_proto = 0;
737 data->encap_size = nf_bridge_encap_header_len(skb);
738 data->size = ETH_HLEN + data->encap_size;
740 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
743 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
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;
750 if (br_validate_ipv6(net, skb))
753 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
755 nf_bridge_update_protocol(skb);
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;
761 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
765 return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
770 nf_bridge_info_free(skb);
771 return br_dev_queue_push_xmit(net, sk, skb);
777 /* PF_BRIDGE/POST_ROUTING ********************************************/
778 static unsigned int br_nf_post_routing(void *priv,
780 const struct nf_hook_state *state)
782 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
783 struct net_device *realoutdev = bridge_parent(skb->dev);
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:
789 * POST_ROUTING was already invoked from the ip stack.
791 if (!nf_bridge || !nf_bridge->physoutdev)
797 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
799 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
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;
811 nf_bridge_pull_encap_header(skb);
812 if (pf == NFPROTO_IPV4)
813 skb->protocol = htons(ETH_P_IP);
815 skb->protocol = htons(ETH_P_IPV6);
817 NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
819 br_nf_dev_queue_xmit);
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,
829 const struct nf_hook_state *state)
831 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
833 if (nf_bridge && !nf_bridge->in_prerouting &&
834 !netif_is_l3_master(skb->dev)) {
835 state->okfn(state->net, state->sk, skb);
842 /* This is called when br_netfilter has called into iptables/netfilter,
843 * and DNAT has taken place on a bridge-forwarded packet.
845 * neigh->output has created a new MAC header, with local br0 MAC
848 * This restores the original MAC saddr of the bridged packet
849 * before invoking bridge forward logic to transmit the packet.
851 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
853 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
855 skb_pull(skb, ETH_HLEN);
856 nf_bridge->bridged_dnat = 0;
858 BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
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;
865 nf_bridge->physoutdev = NULL;
866 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
869 static int br_nf_dev_xmit(struct sk_buff *skb)
871 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
873 if (nf_bridge && nf_bridge->bridged_dnat) {
874 br_nf_pre_routing_finish_bridge_slow(skb);
880 static const struct nf_br_ops br_ops = {
881 .br_dev_xmit_hook = br_nf_dev_xmit,
884 void br_netfilter_enable(void)
887 EXPORT_SYMBOL_GPL(br_netfilter_enable);
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[] = {
893 .hook = br_nf_pre_routing,
894 .pf = NFPROTO_BRIDGE,
895 .hooknum = NF_BR_PRE_ROUTING,
896 .priority = NF_BR_PRI_BRNF,
899 .hook = br_nf_forward_ip,
900 .pf = NFPROTO_BRIDGE,
901 .hooknum = NF_BR_FORWARD,
902 .priority = NF_BR_PRI_BRNF - 1,
905 .hook = br_nf_forward_arp,
906 .pf = NFPROTO_BRIDGE,
907 .hooknum = NF_BR_FORWARD,
908 .priority = NF_BR_PRI_BRNF,
911 .hook = br_nf_post_routing,
912 .pf = NFPROTO_BRIDGE,
913 .hooknum = NF_BR_POST_ROUTING,
914 .priority = NF_BR_PRI_LAST,
917 .hook = ip_sabotage_in,
919 .hooknum = NF_INET_PRE_ROUTING,
920 .priority = NF_IP_PRI_FIRST,
923 .hook = ip_sabotage_in,
925 .hooknum = NF_INET_PRE_ROUTING,
926 .priority = NF_IP6_PRI_FIRST,
930 static int brnf_device_event(struct notifier_block *unused, unsigned long event,
933 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
934 struct brnf_net *brnet;
938 if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
944 brnet = net_generic(net, brnf_net_id);
948 ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
952 brnet->enabled = true;
956 static void __net_exit brnf_exit_net(struct net *net)
958 struct brnf_net *brnet = net_generic(net, brnf_net_id);
963 nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
964 brnet->enabled = false;
967 static struct pernet_operations brnf_net_ops __read_mostly = {
968 .exit = brnf_exit_net,
970 .size = sizeof(struct brnf_net),
973 static struct notifier_block brnf_notifier __read_mostly = {
974 .notifier_call = brnf_device_event,
977 /* recursively invokes nf_hook_slow (again), skipping already-called
978 * hooks (< NF_BR_PRI_BRNF).
980 * Called with rcu read lock held.
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 *,
989 const struct nf_hook_entries *e;
990 struct nf_hook_state state;
991 struct nf_hook_ops **ops;
995 e = rcu_dereference(net->nf.hooks_bridge[hook]);
997 return okfn(net, sk, skb);
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++)
1004 nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
1007 ret = nf_hook_slow(skb, &state, e, i);
1009 ret = okfn(net, sk, skb);
1014 #ifdef CONFIG_SYSCTL
1016 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
1017 void __user *buffer, size_t *lenp, loff_t *ppos)
1021 ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1023 if (write && *(int *)(ctl->data))
1024 *(int *)(ctl->data) = 1;
1028 static struct ctl_table brnf_table[] = {
1030 .procname = "bridge-nf-call-arptables",
1031 .data = &brnf_call_arptables,
1032 .maxlen = sizeof(int),
1034 .proc_handler = brnf_sysctl_call_tables,
1037 .procname = "bridge-nf-call-iptables",
1038 .data = &brnf_call_iptables,
1039 .maxlen = sizeof(int),
1041 .proc_handler = brnf_sysctl_call_tables,
1044 .procname = "bridge-nf-call-ip6tables",
1045 .data = &brnf_call_ip6tables,
1046 .maxlen = sizeof(int),
1048 .proc_handler = brnf_sysctl_call_tables,
1051 .procname = "bridge-nf-filter-vlan-tagged",
1052 .data = &brnf_filter_vlan_tagged,
1053 .maxlen = sizeof(int),
1055 .proc_handler = brnf_sysctl_call_tables,
1058 .procname = "bridge-nf-filter-pppoe-tagged",
1059 .data = &brnf_filter_pppoe_tagged,
1060 .maxlen = sizeof(int),
1062 .proc_handler = brnf_sysctl_call_tables,
1065 .procname = "bridge-nf-pass-vlan-input-dev",
1066 .data = &brnf_pass_vlan_indev,
1067 .maxlen = sizeof(int),
1069 .proc_handler = brnf_sysctl_call_tables,
1075 static int __init br_netfilter_init(void)
1079 ret = register_pernet_subsys(&brnf_net_ops);
1083 ret = register_netdevice_notifier(&brnf_notifier);
1085 unregister_pernet_subsys(&brnf_net_ops);
1089 #ifdef CONFIG_SYSCTL
1090 brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1091 if (brnf_sysctl_header == NULL) {
1093 "br_netfilter: can't register to sysctl.\n");
1094 unregister_netdevice_notifier(&brnf_notifier);
1095 unregister_pernet_subsys(&brnf_net_ops);
1099 RCU_INIT_POINTER(nf_br_ops, &br_ops);
1100 printk(KERN_NOTICE "Bridge firewalling registered\n");
1104 static void __exit br_netfilter_fini(void)
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);
1114 module_init(br_netfilter_init);
1115 module_exit(br_netfilter_fini);
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");