Merge branch 'master' of git://git.infradead.org/~dedekind/ubi-2.6
[linux-2.6] / 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 (maintainer)   <bdschuym@pandora.be>
8  *
9  *      Changes:
10  *      Apr 29 2003: physdev module support (bdschuym)
11  *      Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
12  *      Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
13  *                   (bdschuym)
14  *      Sep 01 2004: add IPv6 filtering (bdschuym)
15  *
16  *      This program is free software; you can redistribute it and/or
17  *      modify it under the terms of the GNU General Public License
18  *      as published by the Free Software Foundation; either version
19  *      2 of the License, or (at your option) any later version.
20  *
21  *      Lennert dedicates this file to Kerstin Wurdinger.
22  */
23
24 #include <linux/module.h>
25 #include <linux/kernel.h>
26 #include <linux/ip.h>
27 #include <linux/netdevice.h>
28 #include <linux/skbuff.h>
29 #include <linux/if_arp.h>
30 #include <linux/if_ether.h>
31 #include <linux/if_vlan.h>
32 #include <linux/if_pppox.h>
33 #include <linux/ppp_defs.h>
34 #include <linux/netfilter_bridge.h>
35 #include <linux/netfilter_ipv4.h>
36 #include <linux/netfilter_ipv6.h>
37 #include <linux/netfilter_arp.h>
38 #include <linux/in_route.h>
39 #include <linux/inetdevice.h>
40
41 #include <net/ip.h>
42 #include <net/ipv6.h>
43 #include <net/route.h>
44
45 #include <asm/uaccess.h>
46 #include "br_private.h"
47 #ifdef CONFIG_SYSCTL
48 #include <linux/sysctl.h>
49 #endif
50
51 #define skb_origaddr(skb)        (((struct bridge_skb_cb *) \
52                                  (skb->nf_bridge->data))->daddr.ipv4)
53 #define store_orig_dstaddr(skb)  (skb_origaddr(skb) = ip_hdr(skb)->daddr)
54 #define dnat_took_place(skb)     (skb_origaddr(skb) != ip_hdr(skb)->daddr)
55
56 #ifdef CONFIG_SYSCTL
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 = 1;
62 static int brnf_filter_pppoe_tagged __read_mostly = 1;
63 #else
64 #define brnf_filter_vlan_tagged 1
65 #define brnf_filter_pppoe_tagged 1
66 #endif
67
68 static inline __be16 vlan_proto(const struct sk_buff *skb)
69 {
70         return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
71 }
72
73 #define IS_VLAN_IP(skb) \
74         (skb->protocol == htons(ETH_P_8021Q) && \
75          vlan_proto(skb) == htons(ETH_P_IP) &&  \
76          brnf_filter_vlan_tagged)
77
78 #define IS_VLAN_IPV6(skb) \
79         (skb->protocol == htons(ETH_P_8021Q) && \
80          vlan_proto(skb) == htons(ETH_P_IPV6) &&\
81          brnf_filter_vlan_tagged)
82
83 #define IS_VLAN_ARP(skb) \
84         (skb->protocol == htons(ETH_P_8021Q) && \
85          vlan_proto(skb) == htons(ETH_P_ARP) && \
86          brnf_filter_vlan_tagged)
87
88 static inline __be16 pppoe_proto(const struct sk_buff *skb)
89 {
90         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
91                             sizeof(struct pppoe_hdr)));
92 }
93
94 #define IS_PPPOE_IP(skb) \
95         (skb->protocol == htons(ETH_P_PPP_SES) && \
96          pppoe_proto(skb) == htons(PPP_IP) && \
97          brnf_filter_pppoe_tagged)
98
99 #define IS_PPPOE_IPV6(skb) \
100         (skb->protocol == htons(ETH_P_PPP_SES) && \
101          pppoe_proto(skb) == htons(PPP_IPV6) && \
102          brnf_filter_pppoe_tagged)
103
104 /* We need these fake structures to make netfilter happy --
105  * lots of places assume that skb->dst != NULL, which isn't
106  * all that unreasonable.
107  *
108  * Currently, we fill in the PMTU entry because netfilter
109  * refragmentation needs it, and the rt_flags entry because
110  * ipt_REJECT needs it.  Future netfilter modules might
111  * require us to fill additional fields. */
112 static struct net_device __fake_net_device = {
113         .hard_header_len        = ETH_HLEN
114 };
115
116 static struct rtable __fake_rtable = {
117         .u = {
118                 .dst = {
119                         .__refcnt               = ATOMIC_INIT(1),
120                         .dev                    = &__fake_net_device,
121                         .path                   = &__fake_rtable.u.dst,
122                         .metrics                = {[RTAX_MTU - 1] = 1500},
123                         .flags                  = DST_NOXFRM,
124                 }
125         },
126         .rt_flags       = 0,
127 };
128
129 static inline struct net_device *bridge_parent(const struct net_device *dev)
130 {
131         struct net_bridge_port *port = rcu_dereference(dev->br_port);
132
133         return port ? port->br->dev : NULL;
134 }
135
136 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
137 {
138         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
139         if (likely(skb->nf_bridge))
140                 atomic_set(&(skb->nf_bridge->use), 1);
141
142         return skb->nf_bridge;
143 }
144
145 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
146 {
147         unsigned int len = nf_bridge_encap_header_len(skb);
148
149         skb_push(skb, len);
150         skb->network_header -= len;
151 }
152
153 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
154 {
155         unsigned int len = nf_bridge_encap_header_len(skb);
156
157         skb_pull(skb, len);
158         skb->network_header += len;
159 }
160
161 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
162 {
163         unsigned int len = nf_bridge_encap_header_len(skb);
164
165         skb_pull_rcsum(skb, len);
166         skb->network_header += len;
167 }
168
169 static inline void nf_bridge_save_header(struct sk_buff *skb)
170 {
171         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
172
173         skb_copy_from_linear_data_offset(skb, -header_size,
174                                          skb->nf_bridge->data, header_size);
175 }
176
177 /*
178  * When forwarding bridge frames, we save a copy of the original
179  * header before processing.
180  */
181 int nf_bridge_copy_header(struct sk_buff *skb)
182 {
183         int err;
184         int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb);
185
186         err = skb_cow_head(skb, header_size);
187         if (err)
188                 return err;
189
190         skb_copy_to_linear_data_offset(skb, -header_size,
191                                        skb->nf_bridge->data, header_size);
192         __skb_push(skb, nf_bridge_encap_header_len(skb));
193         return 0;
194 }
195
196 /* PF_BRIDGE/PRE_ROUTING *********************************************/
197 /* Undo the changes made for ip6tables PREROUTING and continue the
198  * bridge PRE_ROUTING hook. */
199 static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
200 {
201         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
202
203         if (nf_bridge->mask & BRNF_PKT_TYPE) {
204                 skb->pkt_type = PACKET_OTHERHOST;
205                 nf_bridge->mask ^= BRNF_PKT_TYPE;
206         }
207         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
208
209         skb->dst = (struct dst_entry *)&__fake_rtable;
210         dst_hold(skb->dst);
211
212         skb->dev = nf_bridge->physindev;
213         nf_bridge_push_encap_header(skb);
214         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
215                        br_handle_frame_finish, 1);
216
217         return 0;
218 }
219
220 static void __br_dnat_complain(void)
221 {
222         static unsigned long last_complaint;
223
224         if (jiffies - last_complaint >= 5 * HZ) {
225                 printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
226                        "forwarding to be enabled\n");
227                 last_complaint = jiffies;
228         }
229 }
230
231 /* This requires some explaining. If DNAT has taken place,
232  * we will need to fix up the destination Ethernet address,
233  * and this is a tricky process.
234  *
235  * There are two cases to consider:
236  * 1. The packet was DNAT'ed to a device in the same bridge
237  *    port group as it was received on. We can still bridge
238  *    the packet.
239  * 2. The packet was DNAT'ed to a different device, either
240  *    a non-bridged device or another bridge port group.
241  *    The packet will need to be routed.
242  *
243  * The correct way of distinguishing between these two cases is to
244  * call ip_route_input() and to look at skb->dst->dev, which is
245  * changed to the destination device if ip_route_input() succeeds.
246  *
247  * Let us first consider the case that ip_route_input() succeeds:
248  *
249  * If skb->dst->dev equals the logical bridge device the packet
250  * came in on, we can consider this bridging. We then call
251  * skb->dst->output() which will make the packet enter br_nf_local_out()
252  * not much later. In that function it is assured that the iptables
253  * FORWARD chain is traversed for the packet.
254  *
255  * Otherwise, the packet is considered to be routed and we just
256  * change the destination MAC address so that the packet will
257  * later be passed up to the IP stack to be routed. For a redirected
258  * packet, ip_route_input() will give back the localhost as output device,
259  * which differs from the bridge device.
260  *
261  * Let us now consider the case that ip_route_input() fails:
262  *
263  * This can be because the destination address is martian, in which case
264  * the packet will be dropped.
265  * After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
266  * will fail, while __ip_route_output_key() will return success. The source
267  * address for __ip_route_output_key() is set to zero, so __ip_route_output_key
268  * thinks we're handling a locally generated packet and won't care
269  * if IP forwarding is allowed. We send a warning message to the users's
270  * log telling her to put IP forwarding on.
271  *
272  * ip_route_input() will also fail if there is no route available.
273  * In that case we just drop the packet.
274  *
275  * --Lennert, 20020411
276  * --Bart, 20020416 (updated)
277  * --Bart, 20021007 (updated)
278  * --Bart, 20062711 (updated) */
279 static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
280 {
281         if (skb->pkt_type == PACKET_OTHERHOST) {
282                 skb->pkt_type = PACKET_HOST;
283                 skb->nf_bridge->mask |= BRNF_PKT_TYPE;
284         }
285         skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
286
287         skb->dev = bridge_parent(skb->dev);
288         if (!skb->dev)
289                 kfree_skb(skb);
290         else {
291                 nf_bridge_pull_encap_header(skb);
292                 skb->dst->output(skb);
293         }
294         return 0;
295 }
296
297 static int br_nf_pre_routing_finish(struct sk_buff *skb)
298 {
299         struct net_device *dev = skb->dev;
300         struct iphdr *iph = ip_hdr(skb);
301         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
302         int err;
303
304         if (nf_bridge->mask & BRNF_PKT_TYPE) {
305                 skb->pkt_type = PACKET_OTHERHOST;
306                 nf_bridge->mask ^= BRNF_PKT_TYPE;
307         }
308         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
309         if (dnat_took_place(skb)) {
310                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
311                         struct rtable *rt;
312                         struct flowi fl = {
313                                 .nl_u = {
314                                         .ip4_u = {
315                                                  .daddr = iph->daddr,
316                                                  .saddr = 0,
317                                                  .tos = RT_TOS(iph->tos) },
318                                 },
319                                 .proto = 0,
320                         };
321                         struct in_device *in_dev = in_dev_get(dev);
322
323                         /* If err equals -EHOSTUNREACH the error is due to a
324                          * martian destination or due to the fact that
325                          * forwarding is disabled. For most martian packets,
326                          * ip_route_output_key() will fail. It won't fail for 2 types of
327                          * martian destinations: loopback destinations and destination
328                          * 0.0.0.0. In both cases the packet will be dropped because the
329                          * destination is the loopback device and not the bridge. */
330                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
331                                 goto free_skb;
332
333                         if (!ip_route_output_key(&rt, &fl)) {
334                                 /* - Bridged-and-DNAT'ed traffic doesn't
335                                  *   require ip_forwarding. */
336                                 if (((struct dst_entry *)rt)->dev == dev) {
337                                         skb->dst = (struct dst_entry *)rt;
338                                         goto bridged_dnat;
339                                 }
340                                 /* we are sure that forwarding is disabled, so printing
341                                  * this message is no problem. Note that the packet could
342                                  * still have a martian destination address, in which case
343                                  * the packet could be dropped even if forwarding were enabled */
344                                 __br_dnat_complain();
345                                 dst_release((struct dst_entry *)rt);
346                         }
347 free_skb:
348                         kfree_skb(skb);
349                         return 0;
350                 } else {
351                         if (skb->dst->dev == dev) {
352 bridged_dnat:
353                                 /* Tell br_nf_local_out this is a
354                                  * bridged frame */
355                                 nf_bridge->mask |= BRNF_BRIDGED_DNAT;
356                                 skb->dev = nf_bridge->physindev;
357                                 nf_bridge_push_encap_header(skb);
358                                 NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
359                                                skb, skb->dev, NULL,
360                                                br_nf_pre_routing_finish_bridge,
361                                                1);
362                                 return 0;
363                         }
364                         memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
365                         skb->pkt_type = PACKET_HOST;
366                 }
367         } else {
368                 skb->dst = (struct dst_entry *)&__fake_rtable;
369                 dst_hold(skb->dst);
370         }
371
372         skb->dev = nf_bridge->physindev;
373         nf_bridge_push_encap_header(skb);
374         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
375                        br_handle_frame_finish, 1);
376
377         return 0;
378 }
379
380 /* Some common code for IPv4/IPv6 */
381 static struct net_device *setup_pre_routing(struct sk_buff *skb)
382 {
383         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
384
385         if (skb->pkt_type == PACKET_OTHERHOST) {
386                 skb->pkt_type = PACKET_HOST;
387                 nf_bridge->mask |= BRNF_PKT_TYPE;
388         }
389
390         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
391         nf_bridge->physindev = skb->dev;
392         skb->dev = bridge_parent(skb->dev);
393
394         return skb->dev;
395 }
396
397 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
398 static int check_hbh_len(struct sk_buff *skb)
399 {
400         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
401         u32 pkt_len;
402         const unsigned char *nh = skb_network_header(skb);
403         int off = raw - nh;
404         int len = (raw[1] + 1) << 3;
405
406         if ((raw + len) - skb->data > skb_headlen(skb))
407                 goto bad;
408
409         off += 2;
410         len -= 2;
411
412         while (len > 0) {
413                 int optlen = nh[off + 1] + 2;
414
415                 switch (nh[off]) {
416                 case IPV6_TLV_PAD0:
417                         optlen = 1;
418                         break;
419
420                 case IPV6_TLV_PADN:
421                         break;
422
423                 case IPV6_TLV_JUMBO:
424                         if (nh[off + 1] != 4 || (off & 3) != 2)
425                                 goto bad;
426                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
427                         if (pkt_len <= IPV6_MAXPLEN ||
428                             ipv6_hdr(skb)->payload_len)
429                                 goto bad;
430                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
431                                 goto bad;
432                         if (pskb_trim_rcsum(skb,
433                                             pkt_len + sizeof(struct ipv6hdr)))
434                                 goto bad;
435                         nh = skb_network_header(skb);
436                         break;
437                 default:
438                         if (optlen > len)
439                                 goto bad;
440                         break;
441                 }
442                 off += optlen;
443                 len -= optlen;
444         }
445         if (len == 0)
446                 return 0;
447 bad:
448         return -1;
449
450 }
451
452 /* Replicate the checks that IPv6 does on packet reception and pass the packet
453  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
454 static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
455                                            struct sk_buff *skb,
456                                            const struct net_device *in,
457                                            const struct net_device *out,
458                                            int (*okfn)(struct sk_buff *))
459 {
460         struct ipv6hdr *hdr;
461         u32 pkt_len;
462
463         if (skb->len < sizeof(struct ipv6hdr))
464                 goto inhdr_error;
465
466         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
467                 goto inhdr_error;
468
469         hdr = ipv6_hdr(skb);
470
471         if (hdr->version != 6)
472                 goto inhdr_error;
473
474         pkt_len = ntohs(hdr->payload_len);
475
476         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
477                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
478                         goto inhdr_error;
479                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
480                         goto inhdr_error;
481         }
482         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
483                 goto inhdr_error;
484
485         nf_bridge_put(skb->nf_bridge);
486         if (!nf_bridge_alloc(skb))
487                 return NF_DROP;
488         if (!setup_pre_routing(skb))
489                 return NF_DROP;
490
491         NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
492                 br_nf_pre_routing_finish_ipv6);
493
494         return NF_STOLEN;
495
496 inhdr_error:
497         return NF_DROP;
498 }
499
500 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
501  * Replicate the checks that IPv4 does on packet reception.
502  * Set skb->dev to the bridge device (i.e. parent of the
503  * receiving device) to make netfilter happy, the REDIRECT
504  * target in particular.  Save the original destination IP
505  * address to be able to detect DNAT afterwards. */
506 static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
507                                       const struct net_device *in,
508                                       const struct net_device *out,
509                                       int (*okfn)(struct sk_buff *))
510 {
511         struct iphdr *iph;
512         struct sk_buff *skb = *pskb;
513         __u32 len = nf_bridge_encap_header_len(skb);
514
515         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
516                 return NF_STOLEN;
517
518         if (unlikely(!pskb_may_pull(skb, len)))
519                 goto out;
520
521         if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) ||
522             IS_PPPOE_IPV6(skb)) {
523 #ifdef CONFIG_SYSCTL
524                 if (!brnf_call_ip6tables)
525                         return NF_ACCEPT;
526 #endif
527                 nf_bridge_pull_encap_header_rcsum(skb);
528                 return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
529         }
530 #ifdef CONFIG_SYSCTL
531         if (!brnf_call_iptables)
532                 return NF_ACCEPT;
533 #endif
534
535         if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) &&
536             !IS_PPPOE_IP(skb))
537                 return NF_ACCEPT;
538
539         nf_bridge_pull_encap_header_rcsum(skb);
540
541         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
542                 goto inhdr_error;
543
544         iph = ip_hdr(skb);
545         if (iph->ihl < 5 || iph->version != 4)
546                 goto inhdr_error;
547
548         if (!pskb_may_pull(skb, 4 * iph->ihl))
549                 goto inhdr_error;
550
551         iph = ip_hdr(skb);
552         if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
553                 goto inhdr_error;
554
555         len = ntohs(iph->tot_len);
556         if (skb->len < len || len < 4 * iph->ihl)
557                 goto inhdr_error;
558
559         pskb_trim_rcsum(skb, len);
560
561         nf_bridge_put(skb->nf_bridge);
562         if (!nf_bridge_alloc(skb))
563                 return NF_DROP;
564         if (!setup_pre_routing(skb))
565                 return NF_DROP;
566         store_orig_dstaddr(skb);
567
568         NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
569                 br_nf_pre_routing_finish);
570
571         return NF_STOLEN;
572
573 inhdr_error:
574 //      IP_INC_STATS_BH(IpInHdrErrors);
575 out:
576         return NF_DROP;
577 }
578
579
580 /* PF_BRIDGE/LOCAL_IN ************************************************/
581 /* The packet is locally destined, which requires a real
582  * dst_entry, so detach the fake one.  On the way up, the
583  * packet would pass through PRE_ROUTING again (which already
584  * took place when the packet entered the bridge), but we
585  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
586  * prevent this from happening. */
587 static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
588                                    const struct net_device *in,
589                                    const struct net_device *out,
590                                    int (*okfn)(struct sk_buff *))
591 {
592         struct sk_buff *skb = *pskb;
593
594         if (skb->dst == (struct dst_entry *)&__fake_rtable) {
595                 dst_release(skb->dst);
596                 skb->dst = NULL;
597         }
598
599         return NF_ACCEPT;
600 }
601
602 /* PF_BRIDGE/FORWARD *************************************************/
603 static int br_nf_forward_finish(struct sk_buff *skb)
604 {
605         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
606         struct net_device *in;
607
608         if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
609                 in = nf_bridge->physindev;
610                 if (nf_bridge->mask & BRNF_PKT_TYPE) {
611                         skb->pkt_type = PACKET_OTHERHOST;
612                         nf_bridge->mask ^= BRNF_PKT_TYPE;
613                 }
614         } else {
615                 in = *((struct net_device **)(skb->cb));
616         }
617         nf_bridge_push_encap_header(skb);
618         NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
619                        skb->dev, br_forward_finish, 1);
620         return 0;
621 }
622
623 /* This is the 'purely bridged' case.  For IP, we pass the packet to
624  * netfilter with indev and outdev set to the bridge device,
625  * but we are still able to filter on the 'real' indev/outdev
626  * because of the physdev module. For ARP, indev and outdev are the
627  * bridge ports. */
628 static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
629                                      const struct net_device *in,
630                                      const struct net_device *out,
631                                      int (*okfn)(struct sk_buff *))
632 {
633         struct sk_buff *skb = *pskb;
634         struct nf_bridge_info *nf_bridge;
635         struct net_device *parent;
636         int pf;
637
638         if (!skb->nf_bridge)
639                 return NF_ACCEPT;
640
641         parent = bridge_parent(out);
642         if (!parent)
643                 return NF_DROP;
644
645         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
646             IS_PPPOE_IP(skb))
647                 pf = PF_INET;
648         else
649                 pf = PF_INET6;
650
651         nf_bridge_pull_encap_header(*pskb);
652
653         nf_bridge = skb->nf_bridge;
654         if (skb->pkt_type == PACKET_OTHERHOST) {
655                 skb->pkt_type = PACKET_HOST;
656                 nf_bridge->mask |= BRNF_PKT_TYPE;
657         }
658
659         /* The physdev module checks on this */
660         nf_bridge->mask |= BRNF_BRIDGED;
661         nf_bridge->physoutdev = skb->dev;
662
663         NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
664                 br_nf_forward_finish);
665
666         return NF_STOLEN;
667 }
668
669 static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
670                                       const struct net_device *in,
671                                       const struct net_device *out,
672                                       int (*okfn)(struct sk_buff *))
673 {
674         struct sk_buff *skb = *pskb;
675         struct net_device **d = (struct net_device **)(skb->cb);
676
677 #ifdef CONFIG_SYSCTL
678         if (!brnf_call_arptables)
679                 return NF_ACCEPT;
680 #endif
681
682         if (skb->protocol != htons(ETH_P_ARP)) {
683                 if (!IS_VLAN_ARP(skb))
684                         return NF_ACCEPT;
685                 nf_bridge_pull_encap_header(*pskb);
686         }
687
688         if (arp_hdr(skb)->ar_pln != 4) {
689                 if (IS_VLAN_ARP(skb))
690                         nf_bridge_push_encap_header(*pskb);
691                 return NF_ACCEPT;
692         }
693         *d = (struct net_device *)in;
694         NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
695                 (struct net_device *)out, br_nf_forward_finish);
696
697         return NF_STOLEN;
698 }
699
700 /* PF_BRIDGE/LOCAL_OUT ***********************************************
701  *
702  * This function sees both locally originated IP packets and forwarded
703  * IP packets (in both cases the destination device is a bridge
704  * device). It also sees bridged-and-DNAT'ed packets.
705  *
706  * If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
707  * and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
708  * will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
709  * NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
710  * will be executed.
711  */
712 static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
713                                     const struct net_device *in,
714                                     const struct net_device *out,
715                                     int (*okfn)(struct sk_buff *))
716 {
717         struct net_device *realindev;
718         struct sk_buff *skb = *pskb;
719         struct nf_bridge_info *nf_bridge;
720
721         if (!skb->nf_bridge)
722                 return NF_ACCEPT;
723
724         nf_bridge = skb->nf_bridge;
725         if (!(nf_bridge->mask & BRNF_BRIDGED_DNAT))
726                 return NF_ACCEPT;
727
728         /* Bridged, take PF_BRIDGE/FORWARD.
729          * (see big note in front of br_nf_pre_routing_finish) */
730         nf_bridge->physoutdev = skb->dev;
731         realindev = nf_bridge->physindev;
732
733         if (nf_bridge->mask & BRNF_PKT_TYPE) {
734                 skb->pkt_type = PACKET_OTHERHOST;
735                 nf_bridge->mask ^= BRNF_PKT_TYPE;
736         }
737         nf_bridge_push_encap_header(skb);
738
739         NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev, skb->dev,
740                 br_forward_finish);
741         return NF_STOLEN;
742 }
743
744 static int br_nf_dev_queue_xmit(struct sk_buff *skb)
745 {
746         if (skb->protocol == htons(ETH_P_IP) &&
747             skb->len > skb->dev->mtu &&
748             !skb_is_gso(skb))
749                 return ip_fragment(skb, br_dev_queue_push_xmit);
750         else
751                 return br_dev_queue_push_xmit(skb);
752 }
753
754 /* PF_BRIDGE/POST_ROUTING ********************************************/
755 static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
756                                        const struct net_device *in,
757                                        const struct net_device *out,
758                                        int (*okfn)(struct sk_buff *))
759 {
760         struct sk_buff *skb = *pskb;
761         struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
762         struct net_device *realoutdev = bridge_parent(skb->dev);
763         int pf;
764
765 #ifdef CONFIG_NETFILTER_DEBUG
766         /* Be very paranoid. This probably won't happen anymore, but let's
767          * keep the check just to be sure... */
768         if (skb_mac_header(skb) < skb->head ||
769             skb_mac_header(skb) + ETH_HLEN > skb->data) {
770                 printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
771                        "bad mac.raw pointer.\n");
772                 goto print_error;
773         }
774 #endif
775
776         if (!nf_bridge)
777                 return NF_ACCEPT;
778
779         if (!realoutdev)
780                 return NF_DROP;
781
782         if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) ||
783             IS_PPPOE_IP(skb))
784                 pf = PF_INET;
785         else
786                 pf = PF_INET6;
787
788 #ifdef CONFIG_NETFILTER_DEBUG
789         if (skb->dst == NULL) {
790                 printk(KERN_INFO "br_netfilter post_routing: skb->dst == NULL\n");
791                 goto print_error;
792         }
793 #endif
794
795         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
796          * about the value of skb->pkt_type. */
797         if (skb->pkt_type == PACKET_OTHERHOST) {
798                 skb->pkt_type = PACKET_HOST;
799                 nf_bridge->mask |= BRNF_PKT_TYPE;
800         }
801
802         nf_bridge_pull_encap_header(skb);
803         nf_bridge_save_header(skb);
804
805 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
806         if (nf_bridge->netoutdev)
807                 realoutdev = nf_bridge->netoutdev;
808 #endif
809         NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
810                 br_nf_dev_queue_xmit);
811
812         return NF_STOLEN;
813
814 #ifdef CONFIG_NETFILTER_DEBUG
815 print_error:
816         if (skb->dev != NULL) {
817                 printk("[%s]", skb->dev->name);
818                 if (realoutdev)
819                         printk("[%s]", realoutdev->name);
820         }
821         printk(" head:%p, raw:%p, data:%p\n", skb->head, skb_mac_header(skb),
822                skb->data);
823         dump_stack();
824         return NF_ACCEPT;
825 #endif
826 }
827
828 /* IP/SABOTAGE *****************************************************/
829 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
830  * for the second time. */
831 static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
832                                    const struct net_device *in,
833                                    const struct net_device *out,
834                                    int (*okfn)(struct sk_buff *))
835 {
836         if ((*pskb)->nf_bridge &&
837             !((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
838                 return NF_STOP;
839         }
840
841         return NF_ACCEPT;
842 }
843
844 /* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
845  * PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
846  * For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
847  * ip_refrag() can return NF_STOLEN. */
848 static struct nf_hook_ops br_nf_ops[] = {
849         { .hook = br_nf_pre_routing,
850           .owner = THIS_MODULE,
851           .pf = PF_BRIDGE,
852           .hooknum = NF_BR_PRE_ROUTING,
853           .priority = NF_BR_PRI_BRNF, },
854         { .hook = br_nf_local_in,
855           .owner = THIS_MODULE,
856           .pf = PF_BRIDGE,
857           .hooknum = NF_BR_LOCAL_IN,
858           .priority = NF_BR_PRI_BRNF, },
859         { .hook = br_nf_forward_ip,
860           .owner = THIS_MODULE,
861           .pf = PF_BRIDGE,
862           .hooknum = NF_BR_FORWARD,
863           .priority = NF_BR_PRI_BRNF - 1, },
864         { .hook = br_nf_forward_arp,
865           .owner = THIS_MODULE,
866           .pf = PF_BRIDGE,
867           .hooknum = NF_BR_FORWARD,
868           .priority = NF_BR_PRI_BRNF, },
869         { .hook = br_nf_local_out,
870           .owner = THIS_MODULE,
871           .pf = PF_BRIDGE,
872           .hooknum = NF_BR_LOCAL_OUT,
873           .priority = NF_BR_PRI_FIRST, },
874         { .hook = br_nf_post_routing,
875           .owner = THIS_MODULE,
876           .pf = PF_BRIDGE,
877           .hooknum = NF_BR_POST_ROUTING,
878           .priority = NF_BR_PRI_LAST, },
879         { .hook = ip_sabotage_in,
880           .owner = THIS_MODULE,
881           .pf = PF_INET,
882           .hooknum = NF_IP_PRE_ROUTING,
883           .priority = NF_IP_PRI_FIRST, },
884         { .hook = ip_sabotage_in,
885           .owner = THIS_MODULE,
886           .pf = PF_INET6,
887           .hooknum = NF_IP6_PRE_ROUTING,
888           .priority = NF_IP6_PRI_FIRST, },
889 };
890
891 #ifdef CONFIG_SYSCTL
892 static
893 int brnf_sysctl_call_tables(ctl_table * ctl, int write, struct file *filp,
894                             void __user * buffer, size_t * lenp, loff_t * ppos)
895 {
896         int ret;
897
898         ret = proc_dointvec(ctl, write, filp, buffer, lenp, ppos);
899
900         if (write && *(int *)(ctl->data))
901                 *(int *)(ctl->data) = 1;
902         return ret;
903 }
904
905 static ctl_table brnf_table[] = {
906         {
907                 .procname       = "bridge-nf-call-arptables",
908                 .data           = &brnf_call_arptables,
909                 .maxlen         = sizeof(int),
910                 .mode           = 0644,
911                 .proc_handler   = &brnf_sysctl_call_tables,
912         },
913         {
914                 .procname       = "bridge-nf-call-iptables",
915                 .data           = &brnf_call_iptables,
916                 .maxlen         = sizeof(int),
917                 .mode           = 0644,
918                 .proc_handler   = &brnf_sysctl_call_tables,
919         },
920         {
921                 .procname       = "bridge-nf-call-ip6tables",
922                 .data           = &brnf_call_ip6tables,
923                 .maxlen         = sizeof(int),
924                 .mode           = 0644,
925                 .proc_handler   = &brnf_sysctl_call_tables,
926         },
927         {
928                 .procname       = "bridge-nf-filter-vlan-tagged",
929                 .data           = &brnf_filter_vlan_tagged,
930                 .maxlen         = sizeof(int),
931                 .mode           = 0644,
932                 .proc_handler   = &brnf_sysctl_call_tables,
933         },
934         {
935                 .procname       = "bridge-nf-filter-pppoe-tagged",
936                 .data           = &brnf_filter_pppoe_tagged,
937                 .maxlen         = sizeof(int),
938                 .mode           = 0644,
939                 .proc_handler   = &brnf_sysctl_call_tables,
940         },
941         { .ctl_name = 0 }
942 };
943
944 static ctl_table brnf_bridge_table[] = {
945         {
946                 .ctl_name       = NET_BRIDGE,
947                 .procname       = "bridge",
948                 .mode           = 0555,
949                 .child          = brnf_table,
950         },
951         { .ctl_name = 0 }
952 };
953
954 static ctl_table brnf_net_table[] = {
955         {
956                 .ctl_name       = CTL_NET,
957                 .procname       = "net",
958                 .mode           = 0555,
959                 .child          = brnf_bridge_table,
960         },
961         { .ctl_name = 0 }
962 };
963 #endif
964
965 int __init br_netfilter_init(void)
966 {
967         int ret;
968
969         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
970         if (ret < 0)
971                 return ret;
972 #ifdef CONFIG_SYSCTL
973         brnf_sysctl_header = register_sysctl_table(brnf_net_table);
974         if (brnf_sysctl_header == NULL) {
975                 printk(KERN_WARNING
976                        "br_netfilter: can't register to sysctl.\n");
977                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
978                 return -ENOMEM;
979         }
980 #endif
981         printk(KERN_NOTICE "Bridge firewalling registered\n");
982         return 0;
983 }
984
985 void br_netfilter_fini(void)
986 {
987         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
988 #ifdef CONFIG_SYSCTL
989         unregister_sysctl_table(brnf_sysctl_header);
990 #endif
991 }