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Root/net/bridge/br_netfilter.c

1	/*
2	* Handle firewalling
3	* Linux ethernet bridge
4	*
5	* Authors:
6	* Lennert Buytenhek <buytenh@gnu.org>
7	* Bart De Schuymer <bdschuym@pandora.be>
8	*
9	* This program is free software; you can redistribute it and/or
10	* modify it under the terms of the GNU General Public License
11	* as published by the Free Software Foundation; either version
12	* 2 of the License, or (at your option) any later version.
13	*
14	* Lennert dedicates this file to Kerstin Wurdinger.
15	*/
16
17	#include <linux/module.h>
18	#include <linux/kernel.h>
19	#include <linux/slab.h>
20	#include <linux/ip.h>
21	#include <linux/netdevice.h>
22	#include <linux/skbuff.h>
23	#include <linux/if_arp.h>
24	#include <linux/if_ether.h>
25	#include <linux/if_vlan.h>
26	#include <linux/if_pppox.h>
27	#include <linux/ppp_defs.h>
28	#include <linux/netfilter_bridge.h>
29	#include <linux/netfilter_ipv4.h>
30	#include <linux/netfilter_ipv6.h>
31	#include <linux/netfilter_arp.h>
32	#include <linux/in_route.h>
33	#include <linux/inetdevice.h>
34
35	#include <net/ip.h>
36	#include <net/ipv6.h>
37	#include <net/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
51	static struct ctl_table_header *brnf_sysctl_header;
52	static int brnf_call_iptables __read_mostly = 1;
53	static int brnf_call_ip6tables __read_mostly = 1;
54	static int brnf_call_arptables __read_mostly = 1;
55	static int brnf_filter_vlan_tagged __read_mostly = 0;
56	static int brnf_filter_pppoe_tagged __read_mostly = 0;
57	#else
58	#define brnf_call_iptables 1
59	#define brnf_call_ip6tables 1
60	#define brnf_call_arptables 1
61	#define brnf_filter_vlan_tagged 0
62	#define brnf_filter_pppoe_tagged 0
63	#endif
64
65	static inline __be16 vlan_proto(const struct sk_buff *skb)
66	{
67	if (vlan_tx_tag_present(skb))
68	return skb->protocol;
69	else if (skb->protocol == htons(ETH_P_8021Q))
70	return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
71	else
72	return 0;
73	}
74
75	#define IS_VLAN_IP(skb) \
76	(vlan_proto(skb) == htons(ETH_P_IP) && \
77	brnf_filter_vlan_tagged)
78
79	#define IS_VLAN_IPV6(skb) \
80	(vlan_proto(skb) == htons(ETH_P_IPV6) && \
81	brnf_filter_vlan_tagged)
82
83	#define IS_VLAN_ARP(skb) \
84	(vlan_proto(skb) == htons(ETH_P_ARP) && \
85	brnf_filter_vlan_tagged)
86
87	static inline __be16 pppoe_proto(const struct sk_buff *skb)
88	{
89	return ((__be16 )(skb_mac_header(skb) + ETH_HLEN +
90	sizeof(struct pppoe_hdr)));
91	}
92
93	#define IS_PPPOE_IP(skb) \
94	(skb->protocol == htons(ETH_P_PPP_SES) && \
95	pppoe_proto(skb) == htons(PPP_IP) && \
96	brnf_filter_pppoe_tagged)
97
98	#define IS_PPPOE_IPV6(skb) \
99	(skb->protocol == htons(ETH_P_PPP_SES) && \
100	pppoe_proto(skb) == htons(PPP_IPV6) && \
101	brnf_filter_pppoe_tagged)
102
103	static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
104	{
105	}
106
107	static struct dst_ops fake_dst_ops = {
108	.family = AF_INET,
109	.protocol = cpu_to_be16(ETH_P_IP),
110	.update_pmtu = fake_update_pmtu,
111	};
112
113	/*
114	* Initialize bogus route table used to keep netfilter happy.
115	* Currently, we fill in the PMTU entry because netfilter
116	* refragmentation needs it, and the rt_flags entry because
117	* ipt_REJECT needs it. Future netfilter modules might
118	* require us to fill additional fields.
119	*/
120	void br_netfilter_rtable_init(struct net_bridge *br)
121	{
122	struct rtable *rt = &br->fake_rtable;
123
124	atomic_set(&rt->dst.__refcnt, 1);
125	rt->dst.dev = br->dev;
126	rt->dst.path = &rt->dst;
127	dst_metric_set(&rt->dst, RTAX_MTU, 1500);
128	rt->dst.flags = DST_NOXFRM;
129	rt->dst.ops = &fake_dst_ops;
130	}
131
132	static inline struct rtable bridge_parent_rtable(const struct net_device dev)
133	{
134	struct net_bridge_port *port;
135
136	port = br_port_get_rcu(dev);
137	return port ? &port->br->fake_rtable : NULL;
138	}
139
140	static inline struct net_device bridge_parent(const struct net_device dev)
141	{
142	struct net_bridge_port *port;
143
144	port = br_port_get_rcu(dev);
145	return port ? port->br->dev : NULL;
146	}
147
148	static inline struct nf_bridge_info nf_bridge_alloc(struct sk_buff skb)
149	{
150	skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
151	if (likely(skb->nf_bridge))
152	atomic_set(&(skb->nf_bridge->use), 1);
153
154	return skb->nf_bridge;
155	}
156
157	static inline struct nf_bridge_info nf_bridge_unshare(struct sk_buff skb)
158	{
159	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
160
161	if (atomic_read(&nf_bridge->use) > 1) {
162	struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
163
164	if (tmp) {
165	memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
166	atomic_set(&tmp->use, 1);
167	}
168	nf_bridge_put(nf_bridge);
169	nf_bridge = tmp;
170	}
171	return nf_bridge;
172	}
173
174	static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
175	{
176	unsigned int len = nf_bridge_encap_header_len(skb);
177
178	skb_push(skb, len);
179	skb->network_header -= len;
180	}
181
182	static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
183	{
184	unsigned int len = nf_bridge_encap_header_len(skb);
185
186	skb_pull(skb, len);
187	skb->network_header += len;
188	}
189
190	static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
191	{
192	unsigned int len = nf_bridge_encap_header_len(skb);
193
194	skb_pull_rcsum(skb, len);
195	skb->network_header += len;
196	}
197
198	static inline void nf_bridge_save_header(struct sk_buff *skb)
199	{
200	int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
201
202	skb_copy_from_linear_data_offset(skb, -header_size,
203	skb->nf_bridge->data, header_size);
204	}
205
206	static inline void nf_bridge_update_protocol(struct sk_buff *skb)
207	{
208	if (skb->nf_bridge->mask & BRNF_8021Q)
209	skb->protocol = htons(ETH_P_8021Q);
210	else if (skb->nf_bridge->mask & BRNF_PPPoE)
211	skb->protocol = htons(ETH_P_PPP_SES);
212	}
213
214	/* When handing a packet over to the IP layer
215	* check whether we have a skb that is in the
216	* expected format
217	*/
218
219	static int br_parse_ip_options(struct sk_buff *skb)
220	{
221	struct ip_options *opt;
222	struct iphdr *iph;
223	struct net_device *dev = skb->dev;
224	u32 len;
225
226	iph = ip_hdr(skb);
227	opt = &(IPCB(skb)->opt);
228
229	/* Basic sanity checks */
230	if (iph->ihl < 5 \|\| iph->version != 4)
231	goto inhdr_error;
232
233	if (!pskb_may_pull(skb, iph->ihl*4))
234	goto inhdr_error;
235
236	iph = ip_hdr(skb);
237	if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
238	goto inhdr_error;
239
240	len = ntohs(iph->tot_len);
241	if (skb->len < len) {
242	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
243	goto drop;
244	} else if (len < (iph->ihl*4))
245	goto inhdr_error;
246
247	if (pskb_trim_rcsum(skb, len)) {
248	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
249	goto drop;
250	}
251
252	memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
253	if (iph->ihl == 5)
254	return 0;
255
256	opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
257	if (ip_options_compile(dev_net(dev), opt, skb))
258	goto inhdr_error;
259
260	/* Check correct handling of SRR option */
261	if (unlikely(opt->srr)) {
262	struct in_device *in_dev = __in_dev_get_rcu(dev);
263	if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
264	goto drop;
265
266	if (ip_options_rcv_srr(skb))
267	goto drop;
268	}
269
270	return 0;
271
272	inhdr_error:
273	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
274	drop:
275	return -1;
276	}
277
278	/* Fill in the header for fragmented IP packets handled by
279	* the IPv4 connection tracking code.
280	*/
281	int nf_bridge_copy_header(struct sk_buff *skb)
282	{
283	int err;
284	unsigned int header_size;
285
286	nf_bridge_update_protocol(skb);
287	header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
288	err = skb_cow_head(skb, header_size);
289	if (err)
290	return err;
291
292	skb_copy_to_linear_data_offset(skb, -header_size,
293	skb->nf_bridge->data, header_size);
294	__skb_push(skb, nf_bridge_encap_header_len(skb));
295	return 0;
296	}
297
298	/* PF_BRIDGE/PRE_ROUTING *********************************************/
299	/* Undo the changes made for ip6tables PREROUTING and continue the
300	* bridge PRE_ROUTING hook. */
301	static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
302	{
303	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
304	struct rtable *rt;
305
306	if (nf_bridge->mask & BRNF_PKT_TYPE) {
307	skb->pkt_type = PACKET_OTHERHOST;
308	nf_bridge->mask ^= BRNF_PKT_TYPE;
309	}
310	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
311
312	rt = bridge_parent_rtable(nf_bridge->physindev);
313	if (!rt) {
314	kfree_skb(skb);
315	return 0;
316	}
317	skb_dst_set_noref(skb, &rt->dst);
318
319	skb->dev = nf_bridge->physindev;
320	nf_bridge_update_protocol(skb);
321	nf_bridge_push_encap_header(skb);
322	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
323	br_handle_frame_finish, 1);
324
325	return 0;
326	}
327
328	/* Obtain the correct destination MAC address, while preserving the original
329	* source MAC address. If we already know this address, we just copy it. If we
330	* don't, we use the neighbour framework to find out. In both cases, we make
331	* sure that br_handle_frame_finish() is called afterwards.
332	*/
333	static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
334	{
335	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
336	struct dst_entry *dst;
337
338	skb->dev = bridge_parent(skb->dev);
339	if (!skb->dev)
340	goto free_skb;
341	dst = skb_dst(skb);
342	if (dst->hh) {
343	neigh_hh_bridge(dst->hh, skb);
344	skb->dev = nf_bridge->physindev;
345	return br_handle_frame_finish(skb);
346	} else if (dst->neighbour) {
347	/* the neighbour function below overwrites the complete
348	* MAC header, so we save the Ethernet source address and
349	* protocol number. */
350	skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
351	/* tell br_dev_xmit to continue with forwarding */
352	nf_bridge->mask \|= BRNF_BRIDGED_DNAT;
353	return dst->neighbour->output(skb);
354	}
355	free_skb:
356	kfree_skb(skb);
357	return 0;
358	}
359
360	/* This requires some explaining. If DNAT has taken place,
361	* we will need to fix up the destination Ethernet address.
362	*
363	* There are two cases to consider:
364	* 1. The packet was DNAT'ed to a device in the same bridge
365	* port group as it was received on. We can still bridge
366	* the packet.
367	* 2. The packet was DNAT'ed to a different device, either
368	* a non-bridged device or another bridge port group.
369	* The packet will need to be routed.
370	*
371	* The correct way of distinguishing between these two cases is to
372	* call ip_route_input() and to look at skb->dst->dev, which is
373	* changed to the destination device if ip_route_input() succeeds.
374	*
375	* Let's first consider the case that ip_route_input() succeeds:
376	*
377	* If the output device equals the logical bridge device the packet
378	* came in on, we can consider this bridging. The corresponding MAC
379	* address will be obtained in br_nf_pre_routing_finish_bridge.
380	* Otherwise, the packet is considered to be routed and we just
381	* change the destination MAC address so that the packet will
382	* later be passed up to the IP stack to be routed. For a redirected
383	* packet, ip_route_input() will give back the localhost as output device,
384	* which differs from the bridge device.
385	*
386	* Let's now consider the case that ip_route_input() fails:
387	*
388	* This can be because the destination address is martian, in which case
389	* the packet will be dropped.
390	* If IP forwarding is disabled, ip_route_input() will fail, while
391	* ip_route_output_key() can return success. The source
392	* address for ip_route_output_key() is set to zero, so ip_route_output_key()
393	* thinks we're handling a locally generated packet and won't care
394	* if IP forwarding is enabled. If the output device equals the logical bridge
395	* device, we proceed as if ip_route_input() succeeded. If it differs from the
396	* logical bridge port or if ip_route_output_key() fails we drop the packet.
397	*/
398	static int br_nf_pre_routing_finish(struct sk_buff *skb)
399	{
400	struct net_device *dev = skb->dev;
401	struct iphdr *iph = ip_hdr(skb);
402	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
403	struct rtable *rt;
404	int err;
405
406	if (nf_bridge->mask & BRNF_PKT_TYPE) {
407	skb->pkt_type = PACKET_OTHERHOST;
408	nf_bridge->mask ^= BRNF_PKT_TYPE;
409	}
410	nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
411	if (dnat_took_place(skb)) {
412	if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
413	struct in_device *in_dev = __in_dev_get_rcu(dev);
414
415	/* If err equals -EHOSTUNREACH the error is due to a
416	* martian destination or due to the fact that
417	* forwarding is disabled. For most martian packets,
418	* ip_route_output_key() will fail. It won't fail for 2 types of
419	* martian destinations: loopback destinations and destination
420	* 0.0.0.0. In both cases the packet will be dropped because the
421	* destination is the loopback device and not the bridge. */
422	if (err != -EHOSTUNREACH \|\| !in_dev \|\| IN_DEV_FORWARD(in_dev))
423	goto free_skb;
424
425	rt = ip_route_output(dev_net(dev), iph->daddr, 0,
426	RT_TOS(iph->tos), 0);
427	if (!IS_ERR(rt)) {
428	/* - Bridged-and-DNAT'ed traffic doesn't
429	* require ip_forwarding. */
430	if (rt->dst.dev == dev) {
431	skb_dst_set(skb, &rt->dst);
432	goto bridged_dnat;
433	}
434	ip_rt_put(rt);
435	}
436	free_skb:
437	kfree_skb(skb);
438	return 0;
439	} else {
440	if (skb_dst(skb)->dev == dev) {
441	bridged_dnat:
442	skb->dev = nf_bridge->physindev;
443	nf_bridge_update_protocol(skb);
444	nf_bridge_push_encap_header(skb);
445	NF_HOOK_THRESH(NFPROTO_BRIDGE,
446	NF_BR_PRE_ROUTING,
447	skb, skb->dev, NULL,
448	br_nf_pre_routing_finish_bridge,
449	1);
450	return 0;
451	}
452	memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
453	skb->pkt_type = PACKET_HOST;
454	}
455	} else {
456	rt = bridge_parent_rtable(nf_bridge->physindev);
457	if (!rt) {
458	kfree_skb(skb);
459	return 0;
460	}
461	skb_dst_set_noref(skb, &rt->dst);
462	}
463
464	skb->dev = nf_bridge->physindev;
465	nf_bridge_update_protocol(skb);
466	nf_bridge_push_encap_header(skb);
467	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
468	br_handle_frame_finish, 1);
469
470	return 0;
471	}
472
473	/* Some common code for IPv4/IPv6 */
474	static struct net_device setup_pre_routing(struct sk_buff skb)
475	{
476	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
477
478	if (skb->pkt_type == PACKET_OTHERHOST) {
479	skb->pkt_type = PACKET_HOST;
480	nf_bridge->mask \|= BRNF_PKT_TYPE;
481	}
482
483	nf_bridge->mask \|= BRNF_NF_BRIDGE_PREROUTING;
484	nf_bridge->physindev = skb->dev;
485	skb->dev = bridge_parent(skb->dev);
486	if (skb->protocol == htons(ETH_P_8021Q))
487	nf_bridge->mask \|= BRNF_8021Q;
488	else if (skb->protocol == htons(ETH_P_PPP_SES))
489	nf_bridge->mask \|= BRNF_PPPoE;
490
491	return skb->dev;
492	}
493
494	/* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
495	static int check_hbh_len(struct sk_buff *skb)
496	{
497	unsigned char raw = (u8 )(ipv6_hdr(skb) + 1);
498	u32 pkt_len;
499	const unsigned char *nh = skb_network_header(skb);
500	int off = raw - nh;
501	int len = (raw[1] + 1) << 3;
502
503	if ((raw + len) - skb->data > skb_headlen(skb))
504	goto bad;
505
506	off += 2;
507	len -= 2;
508
509	while (len > 0) {
510	int optlen = nh[off + 1] + 2;
511
512	switch (nh[off]) {
513	case IPV6_TLV_PAD0:
514	optlen = 1;
515	break;
516
517	case IPV6_TLV_PADN:
518	break;
519
520	case IPV6_TLV_JUMBO:
521	if (nh[off + 1] != 4 \|\| (off & 3) != 2)
522	goto bad;
523	pkt_len = ntohl((__be32 ) (nh + off + 2));
524	if (pkt_len <= IPV6_MAXPLEN \|\|
525	ipv6_hdr(skb)->payload_len)
526	goto bad;
527	if (pkt_len > skb->len - sizeof(struct ipv6hdr))
528	goto bad;
529	if (pskb_trim_rcsum(skb,
530	pkt_len + sizeof(struct ipv6hdr)))
531	goto bad;
532	nh = skb_network_header(skb);
533	break;
534	default:
535	if (optlen > len)
536	goto bad;
537	break;
538	}
539	off += optlen;
540	len -= optlen;
541	}
542	if (len == 0)
543	return 0;
544	bad:
545	return -1;
546
547	}
548
549	/* Replicate the checks that IPv6 does on packet reception and pass the packet
550	* to ip6tables, which doesn't support NAT, so things are fairly simple. */
551	static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
552	struct sk_buff *skb,
553	const struct net_device *in,
554	const struct net_device *out,
555	int (okfn)(struct sk_buff ))
556	{
557	struct ipv6hdr *hdr;
558	u32 pkt_len;
559
560	if (skb->len < sizeof(struct ipv6hdr))
561	return NF_DROP;
562
563	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
564	return NF_DROP;
565
566	hdr = ipv6_hdr(skb);
567
568	if (hdr->version != 6)
569	return NF_DROP;
570
571	pkt_len = ntohs(hdr->payload_len);
572
573	if (pkt_len \|\| hdr->nexthdr != NEXTHDR_HOP) {
574	if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
575	return NF_DROP;
576	if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
577	return NF_DROP;
578	}
579	if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
580	return NF_DROP;
581
582	nf_bridge_put(skb->nf_bridge);
583	if (!nf_bridge_alloc(skb))
584	return NF_DROP;
585	if (!setup_pre_routing(skb))
586	return NF_DROP;
587
588	skb->protocol = htons(ETH_P_IPV6);
589	NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
590	br_nf_pre_routing_finish_ipv6);
591
592	return NF_STOLEN;
593	}
594
595	/* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
596	* Replicate the checks that IPv4 does on packet reception.
597	* Set skb->dev to the bridge device (i.e. parent of the
598	* receiving device) to make netfilter happy, the REDIRECT
599	* target in particular. Save the original destination IP
600	* address to be able to detect DNAT afterwards. */
601	static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
602	const struct net_device *in,
603	const struct net_device *out,
604	int (okfn)(struct sk_buff ))
605	{
606	struct net_bridge_port *p;
607	struct net_bridge *br;
608	__u32 len = nf_bridge_encap_header_len(skb);
609
610	if (unlikely(!pskb_may_pull(skb, len)))
611	return NF_DROP;
612
613	p = br_port_get_rcu(in);
614	if (p == NULL)
615	return NF_DROP;
616	br = p->br;
617
618	if (skb->protocol == htons(ETH_P_IPV6) \|\| IS_VLAN_IPV6(skb) \|\|
619	IS_PPPOE_IPV6(skb)) {
620	if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
621	return NF_ACCEPT;
622
623	nf_bridge_pull_encap_header_rcsum(skb);
624	return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
625	}
626
627	if (!brnf_call_iptables && !br->nf_call_iptables)
628	return NF_ACCEPT;
629
630	if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
631	!IS_PPPOE_IP(skb))
632	return NF_ACCEPT;
633
634	nf_bridge_pull_encap_header_rcsum(skb);
635
636	if (br_parse_ip_options(skb))
637	return NF_DROP;
638
639	nf_bridge_put(skb->nf_bridge);
640	if (!nf_bridge_alloc(skb))
641	return NF_DROP;
642	if (!setup_pre_routing(skb))
643	return NF_DROP;
644	store_orig_dstaddr(skb);
645	skb->protocol = htons(ETH_P_IP);
646
647	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
648	br_nf_pre_routing_finish);
649
650	return NF_STOLEN;
651	}
652
653
654	/* PF_BRIDGE/LOCAL_IN ************************************************/
655	/* The packet is locally destined, which requires a real
656	* dst_entry, so detach the fake one. On the way up, the
657	* packet would pass through PRE_ROUTING again (which already
658	* took place when the packet entered the bridge), but we
659	* register an IPv4 PRE_ROUTING 'sabotage' hook that will
660	* prevent this from happening. */
661	static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
662	const struct net_device *in,
663	const struct net_device *out,
664	int (okfn)(struct sk_buff ))
665	{
666	struct rtable *rt = skb_rtable(skb);
667
668	if (rt && rt == bridge_parent_rtable(in))
669	skb_dst_drop(skb);
670
671	return NF_ACCEPT;
672	}
673
674	/* PF_BRIDGE/FORWARD *************************************************/
675	static int br_nf_forward_finish(struct sk_buff *skb)
676	{
677	struct nf_bridge_info *nf_bridge = skb->nf_bridge;
678	struct net_device *in;
679
680	if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
681	in = nf_bridge->physindev;
682	if (nf_bridge->mask & BRNF_PKT_TYPE) {
683	skb->pkt_type = PACKET_OTHERHOST;
684	nf_bridge->mask ^= BRNF_PKT_TYPE;
685	}
686	nf_bridge_update_protocol(skb);
687	} else {
688	in = ((struct net_device *)(skb->cb));
689	}
690	nf_bridge_push_encap_header(skb);
691
692	NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
693	skb->dev, br_forward_finish, 1);
694	return 0;
695	}
696
697	/* This is the 'purely bridged' case. For IP, we pass the packet to
698	* netfilter with indev and outdev set to the bridge device,
699	* but we are still able to filter on the 'real' indev/outdev
700	* because of the physdev module. For ARP, indev and outdev are the
701	* bridge ports. */
702	static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
703	const struct net_device *in,
704	const struct net_device *out,
705	int (okfn)(struct sk_buff ))
706	{
707	struct nf_bridge_info *nf_bridge;
708	struct net_device *parent;
709	u_int8_t pf;
710
711	if (!skb->nf_bridge)
712	return NF_ACCEPT;
713
714	/* Need exclusive nf_bridge_info since we might have multiple
715	* different physoutdevs. */
716	if (!nf_bridge_unshare(skb))
717	return NF_DROP;
718
719	parent = bridge_parent(out);
720	if (!parent)
721	return NF_DROP;
722
723	if (skb->protocol == htons(ETH_P_IP) \|\| IS_VLAN_IP(skb) \|\|
724	IS_PPPOE_IP(skb))
725	pf = PF_INET;
726	else if (skb->protocol == htons(ETH_P_IPV6) \|\| IS_VLAN_IPV6(skb) \|\|
727	IS_PPPOE_IPV6(skb))
728	pf = PF_INET6;
729	else
730	return NF_ACCEPT;
731
732	nf_bridge_pull_encap_header(skb);
733
734	nf_bridge = skb->nf_bridge;
735	if (skb->pkt_type == PACKET_OTHERHOST) {
736	skb->pkt_type = PACKET_HOST;
737	nf_bridge->mask \|= BRNF_PKT_TYPE;
738	}
739
740	if (pf == PF_INET && br_parse_ip_options(skb))
741	return NF_DROP;
742
743	/* The physdev module checks on this */
744	nf_bridge->mask \|= BRNF_BRIDGED;
745	nf_bridge->physoutdev = skb->dev;
746	if (pf == PF_INET)
747	skb->protocol = htons(ETH_P_IP);
748	else
749	skb->protocol = htons(ETH_P_IPV6);
750
751	NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
752	br_nf_forward_finish);
753
754	return NF_STOLEN;
755	}
756
757	static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
758	const struct net_device *in,
759	const struct net_device *out,
760	int (okfn)(struct sk_buff ))
761	{
762	struct net_bridge_port *p;
763	struct net_bridge *br;
764	struct net_device d = (struct net_device )(skb->cb);
765
766	p = br_port_get_rcu(out);
767	if (p == NULL)
768	return NF_ACCEPT;
769	br = p->br;
770
771	if (!brnf_call_arptables && !br->nf_call_arptables)
772	return NF_ACCEPT;
773
774	if (skb->protocol != htons(ETH_P_ARP)) {
775	if (!IS_VLAN_ARP(skb))
776	return NF_ACCEPT;
777	nf_bridge_pull_encap_header(skb);
778	}
779
780	if (arp_hdr(skb)->ar_pln != 4) {
781	if (IS_VLAN_ARP(skb))
782	nf_bridge_push_encap_header(skb);
783	return NF_ACCEPT;
784	}
785	d = (struct net_device )in;
786	NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
787	(struct net_device *)out, br_nf_forward_finish);
788
789	return NF_STOLEN;
790	}
791
792	#if defined(CONFIG_NF_CONNTRACK_IPV4) \|\| defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
793	static int br_nf_dev_queue_xmit(struct sk_buff *skb)
794	{
795	int ret;
796
797	if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
798	skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
799	!skb_is_gso(skb)) {
800	if (br_parse_ip_options(skb))
801	/* Drop invalid packet */
802	return NF_DROP;
803	ret = ip_fragment(skb, br_dev_queue_push_xmit);
804	} else
805	ret = br_dev_queue_push_xmit(skb);
806
807	return ret;
808	}
809	#else
810	static int br_nf_dev_queue_xmit(struct sk_buff *skb)
811	{
812	return br_dev_queue_push_xmit(skb);
813	}
814	#endif
815
816	/* PF_BRIDGE/POST_ROUTING ********************************************/
817	static unsigned int br_nf_post_routing(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 nf_bridge_info *nf_bridge = skb->nf_bridge;
823	struct net_device *realoutdev = bridge_parent(skb->dev);
824	u_int8_t pf;
825
826	if (!nf_bridge \|\| !(nf_bridge->mask & BRNF_BRIDGED))
827	return NF_ACCEPT;
828
829	if (!realoutdev)
830	return NF_DROP;
831
832	if (skb->protocol == htons(ETH_P_IP) \|\| IS_VLAN_IP(skb) \|\|
833	IS_PPPOE_IP(skb))
834	pf = PF_INET;
835	else if (skb->protocol == htons(ETH_P_IPV6) \|\| IS_VLAN_IPV6(skb) \|\|
836	IS_PPPOE_IPV6(skb))
837	pf = PF_INET6;
838	else
839	return NF_ACCEPT;
840
841	/* We assume any code from br_dev_queue_push_xmit onwards doesn't care
842	* about the value of skb->pkt_type. */
843	if (skb->pkt_type == PACKET_OTHERHOST) {
844	skb->pkt_type = PACKET_HOST;
845	nf_bridge->mask \|= BRNF_PKT_TYPE;
846	}
847
848	nf_bridge_pull_encap_header(skb);
849	nf_bridge_save_header(skb);
850	if (pf == PF_INET)
851	skb->protocol = htons(ETH_P_IP);
852	else
853	skb->protocol = htons(ETH_P_IPV6);
854
855	NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
856	br_nf_dev_queue_xmit);
857
858	return NF_STOLEN;
859	}
860
861	/* IP/SABOTAGE *****************************************************/
862	/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
863	* for the second time. */
864	static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
865	const struct net_device *in,
866	const struct net_device *out,
867	int (okfn)(struct sk_buff ))
868	{
869	if (skb->nf_bridge &&
870	!(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
871	return NF_STOP;
872	}
873
874	return NF_ACCEPT;
875	}
876
877	/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
878	* br_dev_queue_push_xmit is called afterwards */
879	static struct nf_hook_ops br_nf_ops[] __read_mostly = {
880	{
881	.hook = br_nf_pre_routing,
882	.owner = THIS_MODULE,
883	.pf = PF_BRIDGE,
884	.hooknum = NF_BR_PRE_ROUTING,
885	.priority = NF_BR_PRI_BRNF,
886	},
887	{
888	.hook = br_nf_local_in,
889	.owner = THIS_MODULE,
890	.pf = PF_BRIDGE,
891	.hooknum = NF_BR_LOCAL_IN,
892	.priority = NF_BR_PRI_BRNF,
893	},
894	{
895	.hook = br_nf_forward_ip,
896	.owner = THIS_MODULE,
897	.pf = PF_BRIDGE,
898	.hooknum = NF_BR_FORWARD,
899	.priority = NF_BR_PRI_BRNF - 1,
900	},
901	{
902	.hook = br_nf_forward_arp,
903	.owner = THIS_MODULE,
904	.pf = PF_BRIDGE,
905	.hooknum = NF_BR_FORWARD,
906	.priority = NF_BR_PRI_BRNF,
907	},
908	{
909	.hook = br_nf_post_routing,
910	.owner = THIS_MODULE,
911	.pf = PF_BRIDGE,
912	.hooknum = NF_BR_POST_ROUTING,
913	.priority = NF_BR_PRI_LAST,
914	},
915	{
916	.hook = ip_sabotage_in,
917	.owner = THIS_MODULE,
918	.pf = PF_INET,
919	.hooknum = NF_INET_PRE_ROUTING,
920	.priority = NF_IP_PRI_FIRST,
921	},
922	{
923	.hook = ip_sabotage_in,
924	.owner = THIS_MODULE,
925	.pf = PF_INET6,
926	.hooknum = NF_INET_PRE_ROUTING,
927	.priority = NF_IP6_PRI_FIRST,
928	},
929	};
930
931	#ifdef CONFIG_SYSCTL
932	static
933	int brnf_sysctl_call_tables(ctl_table * ctl, int write,
934	void __user * buffer, size_t * lenp, loff_t * ppos)
935	{
936	int ret;
937
938	ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
939
940	if (write && (int )(ctl->data))
941	(int )(ctl->data) = 1;
942	return ret;
943	}
944
945	static ctl_table brnf_table[] = {
946	{
947	.procname = "bridge-nf-call-arptables",
948	.data = &brnf_call_arptables,
949	.maxlen = sizeof(int),
950	.mode = 0644,
951	.proc_handler = brnf_sysctl_call_tables,
952	},
953	{
954	.procname = "bridge-nf-call-iptables",
955	.data = &brnf_call_iptables,
956	.maxlen = sizeof(int),
957	.mode = 0644,
958	.proc_handler = brnf_sysctl_call_tables,
959	},
960	{
961	.procname = "bridge-nf-call-ip6tables",
962	.data = &brnf_call_ip6tables,
963	.maxlen = sizeof(int),
964	.mode = 0644,
965	.proc_handler = brnf_sysctl_call_tables,
966	},
967	{
968	.procname = "bridge-nf-filter-vlan-tagged",
969	.data = &brnf_filter_vlan_tagged,
970	.maxlen = sizeof(int),
971	.mode = 0644,
972	.proc_handler = brnf_sysctl_call_tables,
973	},
974	{
975	.procname = "bridge-nf-filter-pppoe-tagged",
976	.data = &brnf_filter_pppoe_tagged,
977	.maxlen = sizeof(int),
978	.mode = 0644,
979	.proc_handler = brnf_sysctl_call_tables,
980	},
981	{ }
982	};
983
984	static struct ctl_path brnf_path[] = {
985	{ .procname = "net", },
986	{ .procname = "bridge", },
987	{ }
988	};
989	#endif
990
991	int __init br_netfilter_init(void)
992	{
993	int ret;
994
995	ret = dst_entries_init(&fake_dst_ops);
996	if (ret < 0)
997	return ret;
998
999	ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1000	if (ret < 0) {
1001	dst_entries_destroy(&fake_dst_ops);
1002	return ret;
1003	}
1004	#ifdef CONFIG_SYSCTL
1005	brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1006	if (brnf_sysctl_header == NULL) {
1007	printk(KERN_WARNING
1008	"br_netfilter: can't register to sysctl.\n");
1009	nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1010	dst_entries_destroy(&fake_dst_ops);
1011	return -ENOMEM;
1012	}
1013	#endif
1014	printk(KERN_NOTICE "Bridge firewalling registered\n");
1015	return 0;
1016	}
1017
1018	void br_netfilter_fini(void)
1019	{
1020	nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1021	#ifdef CONFIG_SYSCTL
1022	unregister_sysctl_table(brnf_sysctl_header);
1023	#endif
1024	dst_entries_destroy(&fake_dst_ops);
1025	}
1026

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