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af_packet: prevent information leak
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / 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;
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
65static 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
87static 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
103static void fake_update_pmtu(struct dst_entry *dst, u32 mtu)
104{
105}
106
107static 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 */
120static const u32 br_dst_default_metrics[RTAX_MAX] = {
121 [RTAX_MTU - 1] = 1500,
122};
123
124void br_netfilter_rtable_init(struct net_bridge *br)
125{
126 struct rtable *rt = &br->fake_rtable;
127
128 atomic_set(&rt->dst.__refcnt, 1);
129 rt->dst.dev = br->dev;
130 rt->dst.path = &rt->dst;
131 dst_init_metrics(&rt->dst, br_dst_default_metrics, true);
132 rt->dst.flags = DST_NOXFRM;
133 rt->dst.ops = &fake_dst_ops;
134}
135
136static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
137{
138 struct net_bridge_port *port;
139
140 port = br_port_get_rcu(dev);
141 return port ? &port->br->fake_rtable : NULL;
142}
143
144static inline struct net_device *bridge_parent(const struct net_device *dev)
145{
146 struct net_bridge_port *port;
147
148 port = br_port_get_rcu(dev);
149 return port ? port->br->dev : NULL;
150}
151
152static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
153{
154 skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
155 if (likely(skb->nf_bridge))
156 atomic_set(&(skb->nf_bridge->use), 1);
157
158 return skb->nf_bridge;
159}
160
161static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
162{
163 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
164
165 if (atomic_read(&nf_bridge->use) > 1) {
166 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
167
168 if (tmp) {
169 memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
170 atomic_set(&tmp->use, 1);
171 }
172 nf_bridge_put(nf_bridge);
173 nf_bridge = tmp;
174 }
175 return nf_bridge;
176}
177
178static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
179{
180 unsigned int len = nf_bridge_encap_header_len(skb);
181
182 skb_push(skb, len);
183 skb->network_header -= len;
184}
185
186static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
187{
188 unsigned int len = nf_bridge_encap_header_len(skb);
189
190 skb_pull(skb, len);
191 skb->network_header += len;
192}
193
194static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
195{
196 unsigned int len = nf_bridge_encap_header_len(skb);
197
198 skb_pull_rcsum(skb, len);
199 skb->network_header += len;
200}
201
202static inline void nf_bridge_save_header(struct sk_buff *skb)
203{
204 int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
205
206 skb_copy_from_linear_data_offset(skb, -header_size,
207 skb->nf_bridge->data, header_size);
208}
209
210static inline void nf_bridge_update_protocol(struct sk_buff *skb)
211{
212 if (skb->nf_bridge->mask & BRNF_8021Q)
213 skb->protocol = htons(ETH_P_8021Q);
214 else if (skb->nf_bridge->mask & BRNF_PPPoE)
215 skb->protocol = htons(ETH_P_PPP_SES);
216}
217
218/* When handing a packet over to the IP layer
219 * check whether we have a skb that is in the
220 * expected format
221 */
222
223static int br_parse_ip_options(struct sk_buff *skb)
224{
225 struct ip_options *opt;
226 const struct iphdr *iph;
227 struct net_device *dev = skb->dev;
228 u32 len;
229
230 iph = ip_hdr(skb);
231 opt = &(IPCB(skb)->opt);
232
233 /* Basic sanity checks */
234 if (iph->ihl < 5 || iph->version != 4)
235 goto inhdr_error;
236
237 if (!pskb_may_pull(skb, iph->ihl*4))
238 goto inhdr_error;
239
240 iph = ip_hdr(skb);
241 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
242 goto inhdr_error;
243
244 len = ntohs(iph->tot_len);
245 if (skb->len < len) {
246 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
247 goto drop;
248 } else if (len < (iph->ihl*4))
249 goto inhdr_error;
250
251 if (pskb_trim_rcsum(skb, len)) {
252 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
253 goto drop;
254 }
255
256 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
257 if (iph->ihl == 5)
258 return 0;
259
260 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
261 if (ip_options_compile(dev_net(dev), opt, skb))
262 goto inhdr_error;
263
264 /* Check correct handling of SRR option */
265 if (unlikely(opt->srr)) {
266 struct in_device *in_dev = __in_dev_get_rcu(dev);
267 if (in_dev && !IN_DEV_SOURCE_ROUTE(in_dev))
268 goto drop;
269
270 if (ip_options_rcv_srr(skb))
271 goto drop;
272 }
273
274 return 0;
275
276inhdr_error:
277 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
278drop:
279 return -1;
280}
281
282/* Fill in the header for fragmented IP packets handled by
283 * the IPv4 connection tracking code.
284 */
285int nf_bridge_copy_header(struct sk_buff *skb)
286{
287 int err;
288 unsigned int header_size;
289
290 nf_bridge_update_protocol(skb);
291 header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
292 err = skb_cow_head(skb, header_size);
293 if (err)
294 return err;
295
296 skb_copy_to_linear_data_offset(skb, -header_size,
297 skb->nf_bridge->data, header_size);
298 __skb_push(skb, nf_bridge_encap_header_len(skb));
299 return 0;
300}
301
302/* PF_BRIDGE/PRE_ROUTING *********************************************/
303/* Undo the changes made for ip6tables PREROUTING and continue the
304 * bridge PRE_ROUTING hook. */
305static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
306{
307 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
308 struct rtable *rt;
309
310 if (nf_bridge->mask & BRNF_PKT_TYPE) {
311 skb->pkt_type = PACKET_OTHERHOST;
312 nf_bridge->mask ^= BRNF_PKT_TYPE;
313 }
314 nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
315
316 rt = bridge_parent_rtable(nf_bridge->physindev);
317 if (!rt) {
318 kfree_skb(skb);
319 return 0;
320 }
321 skb_dst_set_noref(skb, &rt->dst);
322
323 skb->dev = nf_bridge->physindev;
324 nf_bridge_update_protocol(skb);
325 nf_bridge_push_encap_header(skb);
326 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
327 br_handle_frame_finish, 1);
328
329 return 0;
330}
331
332/* Obtain the correct destination MAC address, while preserving the original
333 * source MAC address. If we already know this address, we just copy it. If we
334 * don't, we use the neighbour framework to find out. In both cases, we make
335 * sure that br_handle_frame_finish() is called afterwards.
336 */
337static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
338{
339 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
340 struct dst_entry *dst;
341
342 skb->dev = bridge_parent(skb->dev);
343 if (!skb->dev)
344 goto free_skb;
345 dst = skb_dst(skb);
346 if (dst->hh) {
347 neigh_hh_bridge(dst->hh, skb);
348 skb->dev = nf_bridge->physindev;
349 return br_handle_frame_finish(skb);
350 } else if (dst->neighbour) {
351 /* the neighbour function below overwrites the complete
352 * MAC header, so we save the Ethernet source address and
353 * protocol number. */
354 skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN);
355 /* tell br_dev_xmit to continue with forwarding */
356 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
357 return dst->neighbour->output(skb);
358 }
359free_skb:
360 kfree_skb(skb);
361 return 0;
362}
363
364/* This requires some explaining. If DNAT has taken place,
365 * we will need to fix up the destination Ethernet address.
366 *
367 * There are two cases to consider:
368 * 1. The packet was DNAT'ed to a device in the same bridge
369 * port group as it was received on. We can still bridge
370 * the packet.
371 * 2. The packet was DNAT'ed to a different device, either
372 * a non-bridged device or another bridge port group.
373 * The packet will need to be routed.
374 *
375 * The correct way of distinguishing between these two cases is to
376 * call ip_route_input() and to look at skb->dst->dev, which is
377 * changed to the destination device if ip_route_input() succeeds.
378 *
379 * Let's first consider the case that ip_route_input() succeeds:
380 *
381 * If the output device equals the logical bridge device the packet
382 * came in on, we can consider this bridging. The corresponding MAC
383 * address will be obtained in br_nf_pre_routing_finish_bridge.
384 * Otherwise, the packet is considered to be routed and we just
385 * change the destination MAC address so that the packet will
386 * later be passed up to the IP stack to be routed. For a redirected
387 * packet, ip_route_input() will give back the localhost as output device,
388 * which differs from the bridge device.
389 *
390 * Let's now consider the case that ip_route_input() fails:
391 *
392 * This can be because the destination address is martian, in which case
393 * the packet will be dropped.
394 * If IP forwarding is disabled, ip_route_input() will fail, while
395 * ip_route_output_key() can return success. The source
396 * address for ip_route_output_key() is set to zero, so ip_route_output_key()
397 * thinks we're handling a locally generated packet and won't care
398 * if IP forwarding is enabled. If the output device equals the logical bridge
399 * device, we proceed as if ip_route_input() succeeded. If it differs from the
400 * logical bridge port or if ip_route_output_key() fails we drop the packet.
401 */
402static int br_nf_pre_routing_finish(struct sk_buff *skb)
403{
404 struct net_device *dev = skb->dev;
405 struct iphdr *iph = ip_hdr(skb);
406 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
407 struct rtable *rt;
408 int err;
409
410 if (nf_bridge->mask & BRNF_PKT_TYPE) {
411 skb->pkt_type = PACKET_OTHERHOST;
412 nf_bridge->mask ^= BRNF_PKT_TYPE;
413 }
414 nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
415 if (dnat_took_place(skb)) {
416 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
417 struct in_device *in_dev = __in_dev_get_rcu(dev);
418
419 /* If err equals -EHOSTUNREACH the error is due to a
420 * martian destination or due to the fact that
421 * forwarding is disabled. For most martian packets,
422 * ip_route_output_key() will fail. It won't fail for 2 types of
423 * martian destinations: loopback destinations and destination
424 * 0.0.0.0. In both cases the packet will be dropped because the
425 * destination is the loopback device and not the bridge. */
426 if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
427 goto free_skb;
428
429 rt = ip_route_output(dev_net(dev), iph->daddr, 0,
430 RT_TOS(iph->tos), 0);
431 if (!IS_ERR(rt)) {
432 /* - Bridged-and-DNAT'ed traffic doesn't
433 * require ip_forwarding. */
434 if (rt->dst.dev == dev) {
435 skb_dst_set(skb, &rt->dst);
436 goto bridged_dnat;
437 }
438 ip_rt_put(rt);
439 }
440free_skb:
441 kfree_skb(skb);
442 return 0;
443 } else {
444 if (skb_dst(skb)->dev == dev) {
445bridged_dnat:
446 skb->dev = nf_bridge->physindev;
447 nf_bridge_update_protocol(skb);
448 nf_bridge_push_encap_header(skb);
449 NF_HOOK_THRESH(NFPROTO_BRIDGE,
450 NF_BR_PRE_ROUTING,
451 skb, skb->dev, NULL,
452 br_nf_pre_routing_finish_bridge,
453 1);
454 return 0;
455 }
456 memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
457 skb->pkt_type = PACKET_HOST;
458 }
459 } else {
460 rt = bridge_parent_rtable(nf_bridge->physindev);
461 if (!rt) {
462 kfree_skb(skb);
463 return 0;
464 }
465 skb_dst_set_noref(skb, &rt->dst);
466 }
467
468 skb->dev = nf_bridge->physindev;
469 nf_bridge_update_protocol(skb);
470 nf_bridge_push_encap_header(skb);
471 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
472 br_handle_frame_finish, 1);
473
474 return 0;
475}
476
477/* Some common code for IPv4/IPv6 */
478static struct net_device *setup_pre_routing(struct sk_buff *skb)
479{
480 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
481
482 if (skb->pkt_type == PACKET_OTHERHOST) {
483 skb->pkt_type = PACKET_HOST;
484 nf_bridge->mask |= BRNF_PKT_TYPE;
485 }
486
487 nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
488 nf_bridge->physindev = skb->dev;
489 skb->dev = bridge_parent(skb->dev);
490 if (skb->protocol == htons(ETH_P_8021Q))
491 nf_bridge->mask |= BRNF_8021Q;
492 else if (skb->protocol == htons(ETH_P_PPP_SES))
493 nf_bridge->mask |= BRNF_PPPoE;
494
495 return skb->dev;
496}
497
498/* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
499static int check_hbh_len(struct sk_buff *skb)
500{
501 unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
502 u32 pkt_len;
503 const unsigned char *nh = skb_network_header(skb);
504 int off = raw - nh;
505 int len = (raw[1] + 1) << 3;
506
507 if ((raw + len) - skb->data > skb_headlen(skb))
508 goto bad;
509
510 off += 2;
511 len -= 2;
512
513 while (len > 0) {
514 int optlen = nh[off + 1] + 2;
515
516 switch (nh[off]) {
517 case IPV6_TLV_PAD0:
518 optlen = 1;
519 break;
520
521 case IPV6_TLV_PADN:
522 break;
523
524 case IPV6_TLV_JUMBO:
525 if (nh[off + 1] != 4 || (off & 3) != 2)
526 goto bad;
527 pkt_len = ntohl(*(__be32 *) (nh + off + 2));
528 if (pkt_len <= IPV6_MAXPLEN ||
529 ipv6_hdr(skb)->payload_len)
530 goto bad;
531 if (pkt_len > skb->len - sizeof(struct ipv6hdr))
532 goto bad;
533 if (pskb_trim_rcsum(skb,
534 pkt_len + sizeof(struct ipv6hdr)))
535 goto bad;
536 nh = skb_network_header(skb);
537 break;
538 default:
539 if (optlen > len)
540 goto bad;
541 break;
542 }
543 off += optlen;
544 len -= optlen;
545 }
546 if (len == 0)
547 return 0;
548bad:
549 return -1;
550
551}
552
553/* Replicate the checks that IPv6 does on packet reception and pass the packet
554 * to ip6tables, which doesn't support NAT, so things are fairly simple. */
555static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
556 struct sk_buff *skb,
557 const struct net_device *in,
558 const struct net_device *out,
559 int (*okfn)(struct sk_buff *))
560{
561 const struct ipv6hdr *hdr;
562 u32 pkt_len;
563
564 if (skb->len < sizeof(struct ipv6hdr))
565 return NF_DROP;
566
567 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
568 return NF_DROP;
569
570 hdr = ipv6_hdr(skb);
571
572 if (hdr->version != 6)
573 return NF_DROP;
574
575 pkt_len = ntohs(hdr->payload_len);
576
577 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
578 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
579 return NF_DROP;
580 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
581 return NF_DROP;
582 }
583 if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
584 return NF_DROP;
585
586 nf_bridge_put(skb->nf_bridge);
587 if (!nf_bridge_alloc(skb))
588 return NF_DROP;
589 if (!setup_pre_routing(skb))
590 return NF_DROP;
591
592 skb->protocol = htons(ETH_P_IPV6);
593 NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
594 br_nf_pre_routing_finish_ipv6);
595
596 return NF_STOLEN;
597}
598
599/* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
600 * Replicate the checks that IPv4 does on packet reception.
601 * Set skb->dev to the bridge device (i.e. parent of the
602 * receiving device) to make netfilter happy, the REDIRECT
603 * target in particular. Save the original destination IP
604 * address to be able to detect DNAT afterwards. */
605static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb,
606 const struct net_device *in,
607 const struct net_device *out,
608 int (*okfn)(struct sk_buff *))
609{
610 struct net_bridge_port *p;
611 struct net_bridge *br;
612 __u32 len = nf_bridge_encap_header_len(skb);
613
614 if (unlikely(!pskb_may_pull(skb, len)))
615 return NF_DROP;
616
617 p = br_port_get_rcu(in);
618 if (p == NULL)
619 return NF_DROP;
620 br = p->br;
621
622 if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
623 IS_PPPOE_IPV6(skb)) {
624 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
625 return NF_ACCEPT;
626
627 nf_bridge_pull_encap_header_rcsum(skb);
628 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
629 }
630
631 if (!brnf_call_iptables && !br->nf_call_iptables)
632 return NF_ACCEPT;
633
634 if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
635 !IS_PPPOE_IP(skb))
636 return NF_ACCEPT;
637
638 nf_bridge_pull_encap_header_rcsum(skb);
639
640 if (br_parse_ip_options(skb))
641 return NF_DROP;
642
643 nf_bridge_put(skb->nf_bridge);
644 if (!nf_bridge_alloc(skb))
645 return NF_DROP;
646 if (!setup_pre_routing(skb))
647 return NF_DROP;
648 store_orig_dstaddr(skb);
649 skb->protocol = htons(ETH_P_IP);
650
651 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
652 br_nf_pre_routing_finish);
653
654 return NF_STOLEN;
655}
656
657
658/* PF_BRIDGE/LOCAL_IN ************************************************/
659/* The packet is locally destined, which requires a real
660 * dst_entry, so detach the fake one. On the way up, the
661 * packet would pass through PRE_ROUTING again (which already
662 * took place when the packet entered the bridge), but we
663 * register an IPv4 PRE_ROUTING 'sabotage' hook that will
664 * prevent this from happening. */
665static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb,
666 const struct net_device *in,
667 const struct net_device *out,
668 int (*okfn)(struct sk_buff *))
669{
670 struct rtable *rt = skb_rtable(skb);
671
672 if (rt && rt == bridge_parent_rtable(in))
673 skb_dst_drop(skb);
674
675 return NF_ACCEPT;
676}
677
678/* PF_BRIDGE/FORWARD *************************************************/
679static int br_nf_forward_finish(struct sk_buff *skb)
680{
681 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
682 struct net_device *in;
683
684 if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
685 in = nf_bridge->physindev;
686 if (nf_bridge->mask & BRNF_PKT_TYPE) {
687 skb->pkt_type = PACKET_OTHERHOST;
688 nf_bridge->mask ^= BRNF_PKT_TYPE;
689 }
690 nf_bridge_update_protocol(skb);
691 } else {
692 in = *((struct net_device **)(skb->cb));
693 }
694 nf_bridge_push_encap_header(skb);
695
696 NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in,
697 skb->dev, br_forward_finish, 1);
698 return 0;
699}
700
701/* This is the 'purely bridged' case. For IP, we pass the packet to
702 * netfilter with indev and outdev set to the bridge device,
703 * but we are still able to filter on the 'real' indev/outdev
704 * because of the physdev module. For ARP, indev and outdev are the
705 * bridge ports. */
706static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb,
707 const struct net_device *in,
708 const struct net_device *out,
709 int (*okfn)(struct sk_buff *))
710{
711 struct nf_bridge_info *nf_bridge;
712 struct net_device *parent;
713 u_int8_t pf;
714
715 if (!skb->nf_bridge)
716 return NF_ACCEPT;
717
718 /* Need exclusive nf_bridge_info since we might have multiple
719 * different physoutdevs. */
720 if (!nf_bridge_unshare(skb))
721 return NF_DROP;
722
723 parent = bridge_parent(out);
724 if (!parent)
725 return NF_DROP;
726
727 if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
728 IS_PPPOE_IP(skb))
729 pf = PF_INET;
730 else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
731 IS_PPPOE_IPV6(skb))
732 pf = PF_INET6;
733 else
734 return NF_ACCEPT;
735
736 nf_bridge_pull_encap_header(skb);
737
738 nf_bridge = skb->nf_bridge;
739 if (skb->pkt_type == PACKET_OTHERHOST) {
740 skb->pkt_type = PACKET_HOST;
741 nf_bridge->mask |= BRNF_PKT_TYPE;
742 }
743
744 if (pf == PF_INET && br_parse_ip_options(skb))
745 return NF_DROP;
746
747 /* The physdev module checks on this */
748 nf_bridge->mask |= BRNF_BRIDGED;
749 nf_bridge->physoutdev = skb->dev;
750 if (pf == PF_INET)
751 skb->protocol = htons(ETH_P_IP);
752 else
753 skb->protocol = htons(ETH_P_IPV6);
754
755 NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent,
756 br_nf_forward_finish);
757
758 return NF_STOLEN;
759}
760
761static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb,
762 const struct net_device *in,
763 const struct net_device *out,
764 int (*okfn)(struct sk_buff *))
765{
766 struct net_bridge_port *p;
767 struct net_bridge *br;
768 struct net_device **d = (struct net_device **)(skb->cb);
769
770 p = br_port_get_rcu(out);
771 if (p == NULL)
772 return NF_ACCEPT;
773 br = p->br;
774
775 if (!brnf_call_arptables && !br->nf_call_arptables)
776 return NF_ACCEPT;
777
778 if (skb->protocol != htons(ETH_P_ARP)) {
779 if (!IS_VLAN_ARP(skb))
780 return NF_ACCEPT;
781 nf_bridge_pull_encap_header(skb);
782 }
783
784 if (arp_hdr(skb)->ar_pln != 4) {
785 if (IS_VLAN_ARP(skb))
786 nf_bridge_push_encap_header(skb);
787 return NF_ACCEPT;
788 }
789 *d = (struct net_device *)in;
790 NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
791 (struct net_device *)out, br_nf_forward_finish);
792
793 return NF_STOLEN;
794}
795
796#if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE)
797static int br_nf_dev_queue_xmit(struct sk_buff *skb)
798{
799 int ret;
800
801 if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) &&
802 skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu &&
803 !skb_is_gso(skb)) {
804 if (br_parse_ip_options(skb))
805 /* Drop invalid packet */
806 return NF_DROP;
807 ret = ip_fragment(skb, br_dev_queue_push_xmit);
808 } else
809 ret = br_dev_queue_push_xmit(skb);
810
811 return ret;
812}
813#else
814static int br_nf_dev_queue_xmit(struct sk_buff *skb)
815{
816 return br_dev_queue_push_xmit(skb);
817}
818#endif
819
820/* PF_BRIDGE/POST_ROUTING ********************************************/
821static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb,
822 const struct net_device *in,
823 const struct net_device *out,
824 int (*okfn)(struct sk_buff *))
825{
826 struct nf_bridge_info *nf_bridge = skb->nf_bridge;
827 struct net_device *realoutdev = bridge_parent(skb->dev);
828 u_int8_t pf;
829
830 if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED))
831 return NF_ACCEPT;
832
833 if (!realoutdev)
834 return NF_DROP;
835
836 if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
837 IS_PPPOE_IP(skb))
838 pf = PF_INET;
839 else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
840 IS_PPPOE_IPV6(skb))
841 pf = PF_INET6;
842 else
843 return NF_ACCEPT;
844
845 /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
846 * about the value of skb->pkt_type. */
847 if (skb->pkt_type == PACKET_OTHERHOST) {
848 skb->pkt_type = PACKET_HOST;
849 nf_bridge->mask |= BRNF_PKT_TYPE;
850 }
851
852 nf_bridge_pull_encap_header(skb);
853 nf_bridge_save_header(skb);
854 if (pf == PF_INET)
855 skb->protocol = htons(ETH_P_IP);
856 else
857 skb->protocol = htons(ETH_P_IPV6);
858
859 NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev,
860 br_nf_dev_queue_xmit);
861
862 return NF_STOLEN;
863}
864
865/* IP/SABOTAGE *****************************************************/
866/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
867 * for the second time. */
868static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb,
869 const struct net_device *in,
870 const struct net_device *out,
871 int (*okfn)(struct sk_buff *))
872{
873 if (skb->nf_bridge &&
874 !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
875 return NF_STOP;
876 }
877
878 return NF_ACCEPT;
879}
880
881/* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
882 * br_dev_queue_push_xmit is called afterwards */
883static struct nf_hook_ops br_nf_ops[] __read_mostly = {
884 {
885 .hook = br_nf_pre_routing,
886 .owner = THIS_MODULE,
887 .pf = PF_BRIDGE,
888 .hooknum = NF_BR_PRE_ROUTING,
889 .priority = NF_BR_PRI_BRNF,
890 },
891 {
892 .hook = br_nf_local_in,
893 .owner = THIS_MODULE,
894 .pf = PF_BRIDGE,
895 .hooknum = NF_BR_LOCAL_IN,
896 .priority = NF_BR_PRI_BRNF,
897 },
898 {
899 .hook = br_nf_forward_ip,
900 .owner = THIS_MODULE,
901 .pf = PF_BRIDGE,
902 .hooknum = NF_BR_FORWARD,
903 .priority = NF_BR_PRI_BRNF - 1,
904 },
905 {
906 .hook = br_nf_forward_arp,
907 .owner = THIS_MODULE,
908 .pf = PF_BRIDGE,
909 .hooknum = NF_BR_FORWARD,
910 .priority = NF_BR_PRI_BRNF,
911 },
912 {
913 .hook = br_nf_post_routing,
914 .owner = THIS_MODULE,
915 .pf = PF_BRIDGE,
916 .hooknum = NF_BR_POST_ROUTING,
917 .priority = NF_BR_PRI_LAST,
918 },
919 {
920 .hook = ip_sabotage_in,
921 .owner = THIS_MODULE,
922 .pf = PF_INET,
923 .hooknum = NF_INET_PRE_ROUTING,
924 .priority = NF_IP_PRI_FIRST,
925 },
926 {
927 .hook = ip_sabotage_in,
928 .owner = THIS_MODULE,
929 .pf = PF_INET6,
930 .hooknum = NF_INET_PRE_ROUTING,
931 .priority = NF_IP6_PRI_FIRST,
932 },
933};
934
935#ifdef CONFIG_SYSCTL
936static
937int brnf_sysctl_call_tables(ctl_table * ctl, int write,
938 void __user * buffer, size_t * lenp, loff_t * ppos)
939{
940 int ret;
941
942 ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
943
944 if (write && *(int *)(ctl->data))
945 *(int *)(ctl->data) = 1;
946 return ret;
947}
948
949static ctl_table brnf_table[] = {
950 {
951 .procname = "bridge-nf-call-arptables",
952 .data = &brnf_call_arptables,
953 .maxlen = sizeof(int),
954 .mode = 0644,
955 .proc_handler = brnf_sysctl_call_tables,
956 },
957 {
958 .procname = "bridge-nf-call-iptables",
959 .data = &brnf_call_iptables,
960 .maxlen = sizeof(int),
961 .mode = 0644,
962 .proc_handler = brnf_sysctl_call_tables,
963 },
964 {
965 .procname = "bridge-nf-call-ip6tables",
966 .data = &brnf_call_ip6tables,
967 .maxlen = sizeof(int),
968 .mode = 0644,
969 .proc_handler = brnf_sysctl_call_tables,
970 },
971 {
972 .procname = "bridge-nf-filter-vlan-tagged",
973 .data = &brnf_filter_vlan_tagged,
974 .maxlen = sizeof(int),
975 .mode = 0644,
976 .proc_handler = brnf_sysctl_call_tables,
977 },
978 {
979 .procname = "bridge-nf-filter-pppoe-tagged",
980 .data = &brnf_filter_pppoe_tagged,
981 .maxlen = sizeof(int),
982 .mode = 0644,
983 .proc_handler = brnf_sysctl_call_tables,
984 },
985 { }
986};
987
988static struct ctl_path brnf_path[] = {
989 { .procname = "net", },
990 { .procname = "bridge", },
991 { }
992};
993#endif
994
995int __init br_netfilter_init(void)
996{
997 int ret;
998
999 ret = dst_entries_init(&fake_dst_ops);
1000 if (ret < 0)
1001 return ret;
1002
1003 ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1004 if (ret < 0) {
1005 dst_entries_destroy(&fake_dst_ops);
1006 return ret;
1007 }
1008#ifdef CONFIG_SYSCTL
1009 brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table);
1010 if (brnf_sysctl_header == NULL) {
1011 printk(KERN_WARNING
1012 "br_netfilter: can't register to sysctl.\n");
1013 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1014 dst_entries_destroy(&fake_dst_ops);
1015 return -ENOMEM;
1016 }
1017#endif
1018 printk(KERN_NOTICE "Bridge firewalling registered\n");
1019 return 0;
1020}
1021
1022void br_netfilter_fini(void)
1023{
1024 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1025#ifdef CONFIG_SYSCTL
1026 unregister_sysctl_table(brnf_sysctl_header);
1027#endif
1028 dst_entries_destroy(&fake_dst_ops);
1029}
kernel source for telekom puls (alcatel/mediatek)