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[deliverable/linux.git] / net / bridge / br_netfilter_hooks.c
1 /*
2 * Handle firewalling
3 * Linux ethernet bridge
4 *
5 * Authors:
6 * Lennert Buytenhek <buytenh@gnu.org>
7 * Bart De Schuymer <bdschuym@pandora.be>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
13 *
14 * Lennert dedicates this file to Kerstin Wurdinger.
15 */
16
17 #include <linux/module.h>
18 #include <linux/kernel.h>
19 #include <linux/slab.h>
20 #include <linux/ip.h>
21 #include <linux/netdevice.h>
22 #include <linux/skbuff.h>
23 #include <linux/if_arp.h>
24 #include <linux/if_ether.h>
25 #include <linux/if_vlan.h>
26 #include <linux/if_pppox.h>
27 #include <linux/ppp_defs.h>
28 #include <linux/netfilter_bridge.h>
29 #include <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/addrconf.h>
38 #include <net/route.h>
39 #include <net/netfilter/br_netfilter.h>
40
41 #include <asm/uaccess.h>
42 #include "br_private.h"
43 #ifdef CONFIG_SYSCTL
44 #include <linux/sysctl.h>
45 #endif
46
47 #ifdef CONFIG_SYSCTL
48 static struct ctl_table_header *brnf_sysctl_header;
49 static int brnf_call_iptables __read_mostly = 1;
50 static int brnf_call_ip6tables __read_mostly = 1;
51 static int brnf_call_arptables __read_mostly = 1;
52 static int brnf_filter_vlan_tagged __read_mostly = 0;
53 static int brnf_filter_pppoe_tagged __read_mostly = 0;
54 static int brnf_pass_vlan_indev __read_mostly = 0;
55 #else
56 #define brnf_call_iptables 1
57 #define brnf_call_ip6tables 1
58 #define brnf_call_arptables 1
59 #define brnf_filter_vlan_tagged 0
60 #define brnf_filter_pppoe_tagged 0
61 #define brnf_pass_vlan_indev 0
62 #endif
63
64 #define IS_IP(skb) \
65 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
66
67 #define IS_IPV6(skb) \
68 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
69
70 #define IS_ARP(skb) \
71 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
72
73 static inline __be16 vlan_proto(const struct sk_buff *skb)
74 {
75 if (skb_vlan_tag_present(skb))
76 return skb->protocol;
77 else if (skb->protocol == htons(ETH_P_8021Q))
78 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
79 else
80 return 0;
81 }
82
83 #define IS_VLAN_IP(skb) \
84 (vlan_proto(skb) == htons(ETH_P_IP) && \
85 brnf_filter_vlan_tagged)
86
87 #define IS_VLAN_IPV6(skb) \
88 (vlan_proto(skb) == htons(ETH_P_IPV6) && \
89 brnf_filter_vlan_tagged)
90
91 #define IS_VLAN_ARP(skb) \
92 (vlan_proto(skb) == htons(ETH_P_ARP) && \
93 brnf_filter_vlan_tagged)
94
95 static inline __be16 pppoe_proto(const struct sk_buff *skb)
96 {
97 return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
98 sizeof(struct pppoe_hdr)));
99 }
100
101 #define IS_PPPOE_IP(skb) \
102 (skb->protocol == htons(ETH_P_PPP_SES) && \
103 pppoe_proto(skb) == htons(PPP_IP) && \
104 brnf_filter_pppoe_tagged)
105
106 #define IS_PPPOE_IPV6(skb) \
107 (skb->protocol == htons(ETH_P_PPP_SES) && \
108 pppoe_proto(skb) == htons(PPP_IPV6) && \
109 brnf_filter_pppoe_tagged)
110
111 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
112 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
113
114 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
115 struct brnf_frag_data {
116 char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
117 u8 encap_size;
118 u8 size;
119 u16 vlan_tci;
120 __be16 vlan_proto;
121 };
122
123 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
124 #endif
125
126 static void nf_bridge_info_free(struct sk_buff *skb)
127 {
128 if (skb->nf_bridge) {
129 nf_bridge_put(skb->nf_bridge);
130 skb->nf_bridge = NULL;
131 }
132 }
133
134 static inline struct net_device *bridge_parent(const struct net_device *dev)
135 {
136 struct net_bridge_port *port;
137
138 port = br_port_get_rcu(dev);
139 return port ? port->br->dev : NULL;
140 }
141
142 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
143 {
144 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
145
146 if (atomic_read(&nf_bridge->use) > 1) {
147 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
148
149 if (tmp) {
150 memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
151 atomic_set(&tmp->use, 1);
152 }
153 nf_bridge_put(nf_bridge);
154 nf_bridge = tmp;
155 }
156 return nf_bridge;
157 }
158
159 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
160 {
161 switch (skb->protocol) {
162 case __cpu_to_be16(ETH_P_8021Q):
163 return VLAN_HLEN;
164 case __cpu_to_be16(ETH_P_PPP_SES):
165 return PPPOE_SES_HLEN;
166 default:
167 return 0;
168 }
169 }
170
171 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
172 {
173 unsigned int len = nf_bridge_encap_header_len(skb);
174
175 skb_pull(skb, len);
176 skb->network_header += len;
177 }
178
179 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
180 {
181 unsigned int len = nf_bridge_encap_header_len(skb);
182
183 skb_pull_rcsum(skb, len);
184 skb->network_header += len;
185 }
186
187 /* When handing a packet over to the IP layer
188 * check whether we have a skb that is in the
189 * expected format
190 */
191
192 static int br_validate_ipv4(struct sk_buff *skb)
193 {
194 const struct iphdr *iph;
195 struct net_device *dev = skb->dev;
196 u32 len;
197
198 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
199 goto inhdr_error;
200
201 iph = ip_hdr(skb);
202
203 /* Basic sanity checks */
204 if (iph->ihl < 5 || iph->version != 4)
205 goto inhdr_error;
206
207 if (!pskb_may_pull(skb, iph->ihl*4))
208 goto inhdr_error;
209
210 iph = ip_hdr(skb);
211 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
212 goto inhdr_error;
213
214 len = ntohs(iph->tot_len);
215 if (skb->len < len) {
216 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
217 goto drop;
218 } else if (len < (iph->ihl*4))
219 goto inhdr_error;
220
221 if (pskb_trim_rcsum(skb, len)) {
222 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
223 goto drop;
224 }
225
226 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
227 /* We should really parse IP options here but until
228 * somebody who actually uses IP options complains to
229 * us we'll just silently ignore the options because
230 * we're lazy!
231 */
232 return 0;
233
234 inhdr_error:
235 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
236 drop:
237 return -1;
238 }
239
240 void nf_bridge_update_protocol(struct sk_buff *skb)
241 {
242 switch (skb->nf_bridge->orig_proto) {
243 case BRNF_PROTO_8021Q:
244 skb->protocol = htons(ETH_P_8021Q);
245 break;
246 case BRNF_PROTO_PPPOE:
247 skb->protocol = htons(ETH_P_PPP_SES);
248 break;
249 case BRNF_PROTO_UNCHANGED:
250 break;
251 }
252 }
253
254 /* Obtain the correct destination MAC address, while preserving the original
255 * source MAC address. If we already know this address, we just copy it. If we
256 * don't, we use the neighbour framework to find out. In both cases, we make
257 * sure that br_handle_frame_finish() is called afterwards.
258 */
259 int br_nf_pre_routing_finish_bridge(struct sock *sk, struct sk_buff *skb)
260 {
261 struct neighbour *neigh;
262 struct dst_entry *dst;
263
264 skb->dev = bridge_parent(skb->dev);
265 if (!skb->dev)
266 goto free_skb;
267 dst = skb_dst(skb);
268 neigh = dst_neigh_lookup_skb(dst, skb);
269 if (neigh) {
270 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
271 int ret;
272
273 if (neigh->hh.hh_len) {
274 neigh_hh_bridge(&neigh->hh, skb);
275 skb->dev = nf_bridge->physindev;
276 ret = br_handle_frame_finish(sk, skb);
277 } else {
278 /* the neighbour function below overwrites the complete
279 * MAC header, so we save the Ethernet source address and
280 * protocol number.
281 */
282 skb_copy_from_linear_data_offset(skb,
283 -(ETH_HLEN-ETH_ALEN),
284 nf_bridge->neigh_header,
285 ETH_HLEN-ETH_ALEN);
286 /* tell br_dev_xmit to continue with forwarding */
287 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
288 /* FIXME Need to refragment */
289 ret = neigh->output(neigh, skb);
290 }
291 neigh_release(neigh);
292 return ret;
293 }
294 free_skb:
295 kfree_skb(skb);
296 return 0;
297 }
298
299 static inline bool
300 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
301 const struct nf_bridge_info *nf_bridge)
302 {
303 return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
304 }
305
306 /* This requires some explaining. If DNAT has taken place,
307 * we will need to fix up the destination Ethernet address.
308 * This is also true when SNAT takes place (for the reply direction).
309 *
310 * There are two cases to consider:
311 * 1. The packet was DNAT'ed to a device in the same bridge
312 * port group as it was received on. We can still bridge
313 * the packet.
314 * 2. The packet was DNAT'ed to a different device, either
315 * a non-bridged device or another bridge port group.
316 * The packet will need to be routed.
317 *
318 * The correct way of distinguishing between these two cases is to
319 * call ip_route_input() and to look at skb->dst->dev, which is
320 * changed to the destination device if ip_route_input() succeeds.
321 *
322 * Let's first consider the case that ip_route_input() succeeds:
323 *
324 * If the output device equals the logical bridge device the packet
325 * came in on, we can consider this bridging. The corresponding MAC
326 * address will be obtained in br_nf_pre_routing_finish_bridge.
327 * Otherwise, the packet is considered to be routed and we just
328 * change the destination MAC address so that the packet will
329 * later be passed up to the IP stack to be routed. For a redirected
330 * packet, ip_route_input() will give back the localhost as output device,
331 * which differs from the bridge device.
332 *
333 * Let's now consider the case that ip_route_input() fails:
334 *
335 * This can be because the destination address is martian, in which case
336 * the packet will be dropped.
337 * If IP forwarding is disabled, ip_route_input() will fail, while
338 * ip_route_output_key() can return success. The source
339 * address for ip_route_output_key() is set to zero, so ip_route_output_key()
340 * thinks we're handling a locally generated packet and won't care
341 * if IP forwarding is enabled. If the output device equals the logical bridge
342 * device, we proceed as if ip_route_input() succeeded. If it differs from the
343 * logical bridge port or if ip_route_output_key() fails we drop the packet.
344 */
345 static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb)
346 {
347 struct net_device *dev = skb->dev;
348 struct iphdr *iph = ip_hdr(skb);
349 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
350 struct rtable *rt;
351 int err;
352
353 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
354
355 if (nf_bridge->pkt_otherhost) {
356 skb->pkt_type = PACKET_OTHERHOST;
357 nf_bridge->pkt_otherhost = false;
358 }
359 nf_bridge->mask &= ~BRNF_NF_BRIDGE_PREROUTING;
360 if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
361 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
362 struct in_device *in_dev = __in_dev_get_rcu(dev);
363
364 /* If err equals -EHOSTUNREACH the error is due to a
365 * martian destination or due to the fact that
366 * forwarding is disabled. For most martian packets,
367 * ip_route_output_key() will fail. It won't fail for 2 types of
368 * martian destinations: loopback destinations and destination
369 * 0.0.0.0. In both cases the packet will be dropped because the
370 * destination is the loopback device and not the bridge. */
371 if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
372 goto free_skb;
373
374 rt = ip_route_output(dev_net(dev), iph->daddr, 0,
375 RT_TOS(iph->tos), 0);
376 if (!IS_ERR(rt)) {
377 /* - Bridged-and-DNAT'ed traffic doesn't
378 * require ip_forwarding. */
379 if (rt->dst.dev == dev) {
380 skb_dst_set(skb, &rt->dst);
381 goto bridged_dnat;
382 }
383 ip_rt_put(rt);
384 }
385 free_skb:
386 kfree_skb(skb);
387 return 0;
388 } else {
389 if (skb_dst(skb)->dev == dev) {
390 bridged_dnat:
391 skb->dev = nf_bridge->physindev;
392 nf_bridge_update_protocol(skb);
393 nf_bridge_push_encap_header(skb);
394 NF_HOOK_THRESH(NFPROTO_BRIDGE,
395 NF_BR_PRE_ROUTING,
396 sk, skb, skb->dev, NULL,
397 br_nf_pre_routing_finish_bridge,
398 1);
399 return 0;
400 }
401 ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
402 skb->pkt_type = PACKET_HOST;
403 }
404 } else {
405 rt = bridge_parent_rtable(nf_bridge->physindev);
406 if (!rt) {
407 kfree_skb(skb);
408 return 0;
409 }
410 skb_dst_set_noref(skb, &rt->dst);
411 }
412
413 skb->dev = nf_bridge->physindev;
414 nf_bridge_update_protocol(skb);
415 nf_bridge_push_encap_header(skb);
416 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
417 skb->dev, NULL,
418 br_handle_frame_finish, 1);
419
420 return 0;
421 }
422
423 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
424 {
425 struct net_device *vlan, *br;
426
427 br = bridge_parent(dev);
428 if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
429 return br;
430
431 vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
432 skb_vlan_tag_get(skb) & VLAN_VID_MASK);
433
434 return vlan ? vlan : br;
435 }
436
437 /* Some common code for IPv4/IPv6 */
438 struct net_device *setup_pre_routing(struct sk_buff *skb)
439 {
440 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
441
442 if (skb->pkt_type == PACKET_OTHERHOST) {
443 skb->pkt_type = PACKET_HOST;
444 nf_bridge->pkt_otherhost = true;
445 }
446
447 nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
448 nf_bridge->physindev = skb->dev;
449 skb->dev = brnf_get_logical_dev(skb, skb->dev);
450
451 if (skb->protocol == htons(ETH_P_8021Q))
452 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
453 else if (skb->protocol == htons(ETH_P_PPP_SES))
454 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
455
456 /* Must drop socket now because of tproxy. */
457 skb_orphan(skb);
458 return skb->dev;
459 }
460
461 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
462 * Replicate the checks that IPv4 does on packet reception.
463 * Set skb->dev to the bridge device (i.e. parent of the
464 * receiving device) to make netfilter happy, the REDIRECT
465 * target in particular. Save the original destination IP
466 * address to be able to detect DNAT afterwards. */
467 static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
468 struct sk_buff *skb,
469 const struct nf_hook_state *state)
470 {
471 struct nf_bridge_info *nf_bridge;
472 struct net_bridge_port *p;
473 struct net_bridge *br;
474 __u32 len = nf_bridge_encap_header_len(skb);
475
476 if (unlikely(!pskb_may_pull(skb, len)))
477 return NF_DROP;
478
479 p = br_port_get_rcu(state->in);
480 if (p == NULL)
481 return NF_DROP;
482 br = p->br;
483
484 if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
485 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
486 return NF_ACCEPT;
487
488 nf_bridge_pull_encap_header_rcsum(skb);
489 return br_nf_pre_routing_ipv6(ops, skb, state);
490 }
491
492 if (!brnf_call_iptables && !br->nf_call_iptables)
493 return NF_ACCEPT;
494
495 if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
496 return NF_ACCEPT;
497
498 nf_bridge_pull_encap_header_rcsum(skb);
499
500 if (br_validate_ipv4(skb))
501 return NF_DROP;
502
503 nf_bridge_put(skb->nf_bridge);
504 if (!nf_bridge_alloc(skb))
505 return NF_DROP;
506 if (!setup_pre_routing(skb))
507 return NF_DROP;
508
509 nf_bridge = nf_bridge_info_get(skb);
510 nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
511
512 skb->protocol = htons(ETH_P_IP);
513
514 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,
515 skb->dev, NULL,
516 br_nf_pre_routing_finish);
517
518 return NF_STOLEN;
519 }
520
521
522 /* PF_BRIDGE/LOCAL_IN ************************************************/
523 /* The packet is locally destined, which requires a real
524 * dst_entry, so detach the fake one. On the way up, the
525 * packet would pass through PRE_ROUTING again (which already
526 * took place when the packet entered the bridge), but we
527 * register an IPv4 PRE_ROUTING 'sabotage' hook that will
528 * prevent this from happening. */
529 static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
530 struct sk_buff *skb,
531 const struct nf_hook_state *state)
532 {
533 br_drop_fake_rtable(skb);
534 return NF_ACCEPT;
535 }
536
537 /* PF_BRIDGE/FORWARD *************************************************/
538 static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
539 {
540 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
541 struct net_device *in;
542
543 if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
544
545 if (skb->protocol == htons(ETH_P_IP))
546 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
547
548 if (skb->protocol == htons(ETH_P_IPV6))
549 nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
550
551 in = nf_bridge->physindev;
552 if (nf_bridge->pkt_otherhost) {
553 skb->pkt_type = PACKET_OTHERHOST;
554 nf_bridge->pkt_otherhost = false;
555 }
556 nf_bridge_update_protocol(skb);
557 } else {
558 in = *((struct net_device **)(skb->cb));
559 }
560 nf_bridge_push_encap_header(skb);
561
562 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, sk, skb,
563 in, skb->dev, br_forward_finish, 1);
564 return 0;
565 }
566
567
568 /* This is the 'purely bridged' case. For IP, we pass the packet to
569 * netfilter with indev and outdev set to the bridge device,
570 * but we are still able to filter on the 'real' indev/outdev
571 * because of the physdev module. For ARP, indev and outdev are the
572 * bridge ports. */
573 static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
574 struct sk_buff *skb,
575 const struct nf_hook_state *state)
576 {
577 struct nf_bridge_info *nf_bridge;
578 struct net_device *parent;
579 u_int8_t pf;
580
581 if (!skb->nf_bridge)
582 return NF_ACCEPT;
583
584 /* Need exclusive nf_bridge_info since we might have multiple
585 * different physoutdevs. */
586 if (!nf_bridge_unshare(skb))
587 return NF_DROP;
588
589 nf_bridge = nf_bridge_info_get(skb);
590 if (!nf_bridge)
591 return NF_DROP;
592
593 parent = bridge_parent(state->out);
594 if (!parent)
595 return NF_DROP;
596
597 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
598 pf = NFPROTO_IPV4;
599 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
600 pf = NFPROTO_IPV6;
601 else
602 return NF_ACCEPT;
603
604 nf_bridge_pull_encap_header(skb);
605
606 if (skb->pkt_type == PACKET_OTHERHOST) {
607 skb->pkt_type = PACKET_HOST;
608 nf_bridge->pkt_otherhost = true;
609 }
610
611 if (pf == NFPROTO_IPV4) {
612 if (br_validate_ipv4(skb))
613 return NF_DROP;
614 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
615 }
616
617 if (pf == NFPROTO_IPV6) {
618 if (br_validate_ipv6(skb))
619 return NF_DROP;
620 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
621 }
622
623 nf_bridge->physoutdev = skb->dev;
624 if (pf == NFPROTO_IPV4)
625 skb->protocol = htons(ETH_P_IP);
626 else
627 skb->protocol = htons(ETH_P_IPV6);
628
629 NF_HOOK(pf, NF_INET_FORWARD, NULL, skb,
630 brnf_get_logical_dev(skb, state->in),
631 parent, br_nf_forward_finish);
632
633 return NF_STOLEN;
634 }
635
636 static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
637 struct sk_buff *skb,
638 const struct nf_hook_state *state)
639 {
640 struct net_bridge_port *p;
641 struct net_bridge *br;
642 struct net_device **d = (struct net_device **)(skb->cb);
643
644 p = br_port_get_rcu(state->out);
645 if (p == NULL)
646 return NF_ACCEPT;
647 br = p->br;
648
649 if (!brnf_call_arptables && !br->nf_call_arptables)
650 return NF_ACCEPT;
651
652 if (!IS_ARP(skb)) {
653 if (!IS_VLAN_ARP(skb))
654 return NF_ACCEPT;
655 nf_bridge_pull_encap_header(skb);
656 }
657
658 if (arp_hdr(skb)->ar_pln != 4) {
659 if (IS_VLAN_ARP(skb))
660 nf_bridge_push_encap_header(skb);
661 return NF_ACCEPT;
662 }
663 *d = state->in;
664 NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->sk, skb,
665 state->in, state->out, br_nf_forward_finish);
666
667 return NF_STOLEN;
668 }
669
670 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) || IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
671 static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb)
672 {
673 struct brnf_frag_data *data;
674 int err;
675
676 data = this_cpu_ptr(&brnf_frag_data_storage);
677 err = skb_cow_head(skb, data->size);
678
679 if (err) {
680 kfree_skb(skb);
681 return 0;
682 }
683
684 if (data->vlan_tci) {
685 skb->vlan_tci = data->vlan_tci;
686 skb->vlan_proto = data->vlan_proto;
687 }
688
689 skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
690 __skb_push(skb, data->encap_size);
691
692 nf_bridge_info_free(skb);
693 return br_dev_queue_push_xmit(sk, skb);
694 }
695 #endif
696
697 static int br_nf_ip_fragment(struct sock *sk, struct sk_buff *skb,
698 int (*output)(struct sock *, struct sk_buff *))
699 {
700 unsigned int mtu = ip_skb_dst_mtu(skb);
701 struct iphdr *iph = ip_hdr(skb);
702 struct rtable *rt = skb_rtable(skb);
703 struct net_device *dev = rt->dst.dev;
704
705 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
706 (IPCB(skb)->frag_max_size &&
707 IPCB(skb)->frag_max_size > mtu))) {
708 IP_INC_STATS(dev_net(dev), IPSTATS_MIB_FRAGFAILS);
709 kfree_skb(skb);
710 return -EMSGSIZE;
711 }
712
713 return ip_do_fragment(sk, skb, output);
714 }
715
716 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
717 {
718 if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
719 return PPPOE_SES_HLEN;
720 return 0;
721 }
722
723 static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
724 {
725 struct nf_bridge_info *nf_bridge;
726 unsigned int mtu_reserved;
727
728 mtu_reserved = nf_bridge_mtu_reduction(skb);
729
730 if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
731 nf_bridge_info_free(skb);
732 return br_dev_queue_push_xmit(sk, skb);
733 }
734
735 nf_bridge = nf_bridge_info_get(skb);
736
737 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
738 /* This is wrong! We should preserve the original fragment
739 * boundaries by preserving frag_list rather than refragmenting.
740 */
741 if (skb->protocol == htons(ETH_P_IP)) {
742 struct brnf_frag_data *data;
743
744 if (br_validate_ipv4(skb))
745 return NF_DROP;
746
747 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
748
749 nf_bridge_update_protocol(skb);
750
751 data = this_cpu_ptr(&brnf_frag_data_storage);
752
753 data->vlan_tci = skb->vlan_tci;
754 data->vlan_proto = skb->vlan_proto;
755 data->encap_size = nf_bridge_encap_header_len(skb);
756 data->size = ETH_HLEN + data->encap_size;
757
758 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
759 data->size);
760
761 return br_nf_ip_fragment(sk, skb, br_nf_push_frag_xmit);
762 }
763 #endif
764 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
765 if (skb->protocol == htons(ETH_P_IPV6)) {
766 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
767 struct brnf_frag_data *data;
768
769 if (br_validate_ipv6(skb))
770 return NF_DROP;
771
772 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
773
774 nf_bridge_update_protocol(skb);
775
776 data = this_cpu_ptr(&brnf_frag_data_storage);
777 data->encap_size = nf_bridge_encap_header_len(skb);
778 data->size = ETH_HLEN + data->encap_size;
779
780 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
781 data->size);
782
783 if (v6ops)
784 return v6ops->fragment(sk, skb, br_nf_push_frag_xmit);
785 else
786 return -EMSGSIZE;
787 }
788 #endif
789 nf_bridge_info_free(skb);
790 return br_dev_queue_push_xmit(sk, skb);
791 }
792
793 /* PF_BRIDGE/POST_ROUTING ********************************************/
794 static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
795 struct sk_buff *skb,
796 const struct nf_hook_state *state)
797 {
798 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
799 struct net_device *realoutdev = bridge_parent(skb->dev);
800 u_int8_t pf;
801
802 /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
803 * on a bridge, but was delivered locally and is now being routed:
804 *
805 * POST_ROUTING was already invoked from the ip stack.
806 */
807 if (!nf_bridge || !nf_bridge->physoutdev)
808 return NF_ACCEPT;
809
810 if (!realoutdev)
811 return NF_DROP;
812
813 if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
814 pf = NFPROTO_IPV4;
815 else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
816 pf = NFPROTO_IPV6;
817 else
818 return NF_ACCEPT;
819
820 /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
821 * about the value of skb->pkt_type. */
822 if (skb->pkt_type == PACKET_OTHERHOST) {
823 skb->pkt_type = PACKET_HOST;
824 nf_bridge->pkt_otherhost = true;
825 }
826
827 nf_bridge_pull_encap_header(skb);
828 if (pf == NFPROTO_IPV4)
829 skb->protocol = htons(ETH_P_IP);
830 else
831 skb->protocol = htons(ETH_P_IPV6);
832
833 NF_HOOK(pf, NF_INET_POST_ROUTING, state->sk, skb,
834 NULL, realoutdev,
835 br_nf_dev_queue_xmit);
836
837 return NF_STOLEN;
838 }
839
840 /* IP/SABOTAGE *****************************************************/
841 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
842 * for the second time. */
843 static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
844 struct sk_buff *skb,
845 const struct nf_hook_state *state)
846 {
847 if (skb->nf_bridge &&
848 !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
849 return NF_STOP;
850 }
851
852 return NF_ACCEPT;
853 }
854
855 /* This is called when br_netfilter has called into iptables/netfilter,
856 * and DNAT has taken place on a bridge-forwarded packet.
857 *
858 * neigh->output has created a new MAC header, with local br0 MAC
859 * as saddr.
860 *
861 * This restores the original MAC saddr of the bridged packet
862 * before invoking bridge forward logic to transmit the packet.
863 */
864 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
865 {
866 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
867
868 skb_pull(skb, ETH_HLEN);
869 nf_bridge->mask &= ~BRNF_BRIDGED_DNAT;
870
871 BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
872
873 skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
874 nf_bridge->neigh_header,
875 ETH_HLEN - ETH_ALEN);
876 skb->dev = nf_bridge->physindev;
877
878 nf_bridge->physoutdev = NULL;
879 br_handle_frame_finish(NULL, skb);
880 }
881
882 static int br_nf_dev_xmit(struct sk_buff *skb)
883 {
884 if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
885 br_nf_pre_routing_finish_bridge_slow(skb);
886 return 1;
887 }
888 return 0;
889 }
890
891 static const struct nf_br_ops br_ops = {
892 .br_dev_xmit_hook = br_nf_dev_xmit,
893 };
894
895 void br_netfilter_enable(void)
896 {
897 }
898 EXPORT_SYMBOL_GPL(br_netfilter_enable);
899
900 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
901 * br_dev_queue_push_xmit is called afterwards */
902 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
903 {
904 .hook = br_nf_pre_routing,
905 .owner = THIS_MODULE,
906 .pf = NFPROTO_BRIDGE,
907 .hooknum = NF_BR_PRE_ROUTING,
908 .priority = NF_BR_PRI_BRNF,
909 },
910 {
911 .hook = br_nf_local_in,
912 .owner = THIS_MODULE,
913 .pf = NFPROTO_BRIDGE,
914 .hooknum = NF_BR_LOCAL_IN,
915 .priority = NF_BR_PRI_BRNF,
916 },
917 {
918 .hook = br_nf_forward_ip,
919 .owner = THIS_MODULE,
920 .pf = NFPROTO_BRIDGE,
921 .hooknum = NF_BR_FORWARD,
922 .priority = NF_BR_PRI_BRNF - 1,
923 },
924 {
925 .hook = br_nf_forward_arp,
926 .owner = THIS_MODULE,
927 .pf = NFPROTO_BRIDGE,
928 .hooknum = NF_BR_FORWARD,
929 .priority = NF_BR_PRI_BRNF,
930 },
931 {
932 .hook = br_nf_post_routing,
933 .owner = THIS_MODULE,
934 .pf = NFPROTO_BRIDGE,
935 .hooknum = NF_BR_POST_ROUTING,
936 .priority = NF_BR_PRI_LAST,
937 },
938 {
939 .hook = ip_sabotage_in,
940 .owner = THIS_MODULE,
941 .pf = NFPROTO_IPV4,
942 .hooknum = NF_INET_PRE_ROUTING,
943 .priority = NF_IP_PRI_FIRST,
944 },
945 {
946 .hook = ip_sabotage_in,
947 .owner = THIS_MODULE,
948 .pf = NFPROTO_IPV6,
949 .hooknum = NF_INET_PRE_ROUTING,
950 .priority = NF_IP6_PRI_FIRST,
951 },
952 };
953
954 #ifdef CONFIG_SYSCTL
955 static
956 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
957 void __user *buffer, size_t *lenp, loff_t *ppos)
958 {
959 int ret;
960
961 ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
962
963 if (write && *(int *)(ctl->data))
964 *(int *)(ctl->data) = 1;
965 return ret;
966 }
967
968 static struct ctl_table brnf_table[] = {
969 {
970 .procname = "bridge-nf-call-arptables",
971 .data = &brnf_call_arptables,
972 .maxlen = sizeof(int),
973 .mode = 0644,
974 .proc_handler = brnf_sysctl_call_tables,
975 },
976 {
977 .procname = "bridge-nf-call-iptables",
978 .data = &brnf_call_iptables,
979 .maxlen = sizeof(int),
980 .mode = 0644,
981 .proc_handler = brnf_sysctl_call_tables,
982 },
983 {
984 .procname = "bridge-nf-call-ip6tables",
985 .data = &brnf_call_ip6tables,
986 .maxlen = sizeof(int),
987 .mode = 0644,
988 .proc_handler = brnf_sysctl_call_tables,
989 },
990 {
991 .procname = "bridge-nf-filter-vlan-tagged",
992 .data = &brnf_filter_vlan_tagged,
993 .maxlen = sizeof(int),
994 .mode = 0644,
995 .proc_handler = brnf_sysctl_call_tables,
996 },
997 {
998 .procname = "bridge-nf-filter-pppoe-tagged",
999 .data = &brnf_filter_pppoe_tagged,
1000 .maxlen = sizeof(int),
1001 .mode = 0644,
1002 .proc_handler = brnf_sysctl_call_tables,
1003 },
1004 {
1005 .procname = "bridge-nf-pass-vlan-input-dev",
1006 .data = &brnf_pass_vlan_indev,
1007 .maxlen = sizeof(int),
1008 .mode = 0644,
1009 .proc_handler = brnf_sysctl_call_tables,
1010 },
1011 { }
1012 };
1013 #endif
1014
1015 static int __init br_netfilter_init(void)
1016 {
1017 int ret;
1018
1019 ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1020 if (ret < 0)
1021 return ret;
1022
1023 #ifdef CONFIG_SYSCTL
1024 brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1025 if (brnf_sysctl_header == NULL) {
1026 printk(KERN_WARNING
1027 "br_netfilter: can't register to sysctl.\n");
1028 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1029 return -ENOMEM;
1030 }
1031 #endif
1032 RCU_INIT_POINTER(nf_br_ops, &br_ops);
1033 printk(KERN_NOTICE "Bridge firewalling registered\n");
1034 return 0;
1035 }
1036
1037 static void __exit br_netfilter_fini(void)
1038 {
1039 RCU_INIT_POINTER(nf_br_ops, NULL);
1040 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1041 #ifdef CONFIG_SYSCTL
1042 unregister_net_sysctl_table(brnf_sysctl_header);
1043 #endif
1044 }
1045
1046 module_init(br_netfilter_init);
1047 module_exit(br_netfilter_fini);
1048
1049 MODULE_LICENSE("GPL");
1050 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1051 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1052 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
Linux kernel - Deliverables
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