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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 | |
51 | static struct ctl_table_header *brnf_sysctl_header; | |
52 | static int brnf_call_iptables __read_mostly = 1; | |
53 | static int brnf_call_ip6tables __read_mostly = 1; | |
54 | static int brnf_call_arptables __read_mostly = 1; | |
55 | static int brnf_filter_vlan_tagged __read_mostly = 0; | |
56 | static int brnf_filter_pppoe_tagged __read_mostly = 0; | |
57 | #else | |
58 | #define brnf_filter_vlan_tagged 0 | |
59 | #define brnf_filter_pppoe_tagged 0 | |
60 | #endif | |
61 | ||
62 | static inline __be16 vlan_proto(const struct sk_buff *skb) | |
63 | { | |
64 | return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto; | |
65 | } | |
66 | ||
67 | #define IS_VLAN_IP(skb) \ | |
68 | (skb->protocol == htons(ETH_P_8021Q) && \ | |
69 | vlan_proto(skb) == htons(ETH_P_IP) && \ | |
70 | brnf_filter_vlan_tagged) | |
71 | ||
72 | #define IS_VLAN_IPV6(skb) \ | |
73 | (skb->protocol == htons(ETH_P_8021Q) && \ | |
74 | vlan_proto(skb) == htons(ETH_P_IPV6) &&\ | |
75 | brnf_filter_vlan_tagged) | |
76 | ||
77 | #define IS_VLAN_ARP(skb) \ | |
78 | (skb->protocol == htons(ETH_P_8021Q) && \ | |
79 | vlan_proto(skb) == htons(ETH_P_ARP) && \ | |
80 | brnf_filter_vlan_tagged) | |
81 | ||
82 | static inline __be16 pppoe_proto(const struct sk_buff *skb) | |
83 | { | |
84 | return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN + | |
85 | sizeof(struct pppoe_hdr))); | |
86 | } | |
87 | ||
88 | #define IS_PPPOE_IP(skb) \ | |
89 | (skb->protocol == htons(ETH_P_PPP_SES) && \ | |
90 | pppoe_proto(skb) == htons(PPP_IP) && \ | |
91 | brnf_filter_pppoe_tagged) | |
92 | ||
93 | #define IS_PPPOE_IPV6(skb) \ | |
94 | (skb->protocol == htons(ETH_P_PPP_SES) && \ | |
95 | pppoe_proto(skb) == htons(PPP_IPV6) && \ | |
96 | brnf_filter_pppoe_tagged) | |
97 | ||
98 | static void fake_update_pmtu(struct dst_entry *dst, u32 mtu) | |
99 | { | |
100 | } | |
101 | ||
102 | static struct dst_ops fake_dst_ops = { | |
103 | .family = AF_INET, | |
104 | .protocol = cpu_to_be16(ETH_P_IP), | |
105 | .update_pmtu = fake_update_pmtu, | |
106 | .entries = ATOMIC_INIT(0), | |
107 | }; | |
108 | ||
109 | /* | |
110 | * Initialize bogus route table used to keep netfilter happy. | |
111 | * Currently, we fill in the PMTU entry because netfilter | |
112 | * refragmentation needs it, and the rt_flags entry because | |
113 | * ipt_REJECT needs it. Future netfilter modules might | |
114 | * require us to fill additional fields. | |
115 | */ | |
116 | void br_netfilter_rtable_init(struct net_bridge *br) | |
117 | { | |
118 | struct rtable *rt = &br->fake_rtable; | |
119 | ||
120 | atomic_set(&rt->dst.__refcnt, 1); | |
121 | rt->dst.dev = br->dev; | |
122 | rt->dst.path = &rt->dst; | |
123 | rt->dst.metrics[RTAX_MTU - 1] = 1500; | |
124 | rt->dst.flags = DST_NOXFRM; | |
125 | rt->dst.ops = &fake_dst_ops; | |
126 | } | |
127 | ||
128 | static inline struct rtable *bridge_parent_rtable(const struct net_device *dev) | |
129 | { | |
130 | struct net_bridge_port *port = rcu_dereference(dev->br_port); | |
131 | ||
132 | return port ? &port->br->fake_rtable : NULL; | |
133 | } | |
134 | ||
135 | static inline struct net_device *bridge_parent(const struct net_device *dev) | |
136 | { | |
137 | struct net_bridge_port *port = rcu_dereference(dev->br_port); | |
138 | ||
139 | return port ? port->br->dev : NULL; | |
140 | } | |
141 | ||
142 | static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb) | |
143 | { | |
144 | skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC); | |
145 | if (likely(skb->nf_bridge)) | |
146 | atomic_set(&(skb->nf_bridge->use), 1); | |
147 | ||
148 | return skb->nf_bridge; | |
149 | } | |
150 | ||
151 | static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb) | |
152 | { | |
153 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
154 | ||
155 | if (atomic_read(&nf_bridge->use) > 1) { | |
156 | struct nf_bridge_info *tmp = nf_bridge_alloc(skb); | |
157 | ||
158 | if (tmp) { | |
159 | memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info)); | |
160 | atomic_set(&tmp->use, 1); | |
161 | nf_bridge_put(nf_bridge); | |
162 | } | |
163 | nf_bridge = tmp; | |
164 | } | |
165 | return nf_bridge; | |
166 | } | |
167 | ||
168 | static inline void nf_bridge_push_encap_header(struct sk_buff *skb) | |
169 | { | |
170 | unsigned int len = nf_bridge_encap_header_len(skb); | |
171 | ||
172 | skb_push(skb, len); | |
173 | skb->network_header -= len; | |
174 | } | |
175 | ||
176 | static inline void nf_bridge_pull_encap_header(struct sk_buff *skb) | |
177 | { | |
178 | unsigned int len = nf_bridge_encap_header_len(skb); | |
179 | ||
180 | skb_pull(skb, len); | |
181 | skb->network_header += len; | |
182 | } | |
183 | ||
184 | static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb) | |
185 | { | |
186 | unsigned int len = nf_bridge_encap_header_len(skb); | |
187 | ||
188 | skb_pull_rcsum(skb, len); | |
189 | skb->network_header += len; | |
190 | } | |
191 | ||
192 | static inline void nf_bridge_save_header(struct sk_buff *skb) | |
193 | { | |
194 | int header_size = ETH_HLEN + nf_bridge_encap_header_len(skb); | |
195 | ||
196 | skb_copy_from_linear_data_offset(skb, -header_size, | |
197 | skb->nf_bridge->data, header_size); | |
198 | } | |
199 | ||
200 | static inline void nf_bridge_update_protocol(struct sk_buff *skb) | |
201 | { | |
202 | if (skb->nf_bridge->mask & BRNF_8021Q) | |
203 | skb->protocol = htons(ETH_P_8021Q); | |
204 | else if (skb->nf_bridge->mask & BRNF_PPPoE) | |
205 | skb->protocol = htons(ETH_P_PPP_SES); | |
206 | } | |
207 | ||
208 | /* Fill in the header for fragmented IP packets handled by | |
209 | * the IPv4 connection tracking code. | |
210 | */ | |
211 | int nf_bridge_copy_header(struct sk_buff *skb) | |
212 | { | |
213 | int err; | |
214 | unsigned int header_size; | |
215 | ||
216 | nf_bridge_update_protocol(skb); | |
217 | header_size = ETH_HLEN + nf_bridge_encap_header_len(skb); | |
218 | err = skb_cow_head(skb, header_size); | |
219 | if (err) | |
220 | return err; | |
221 | ||
222 | skb_copy_to_linear_data_offset(skb, -header_size, | |
223 | skb->nf_bridge->data, header_size); | |
224 | __skb_push(skb, nf_bridge_encap_header_len(skb)); | |
225 | return 0; | |
226 | } | |
227 | ||
228 | /* PF_BRIDGE/PRE_ROUTING *********************************************/ | |
229 | /* Undo the changes made for ip6tables PREROUTING and continue the | |
230 | * bridge PRE_ROUTING hook. */ | |
231 | static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb) | |
232 | { | |
233 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
234 | struct rtable *rt; | |
235 | ||
236 | if (nf_bridge->mask & BRNF_PKT_TYPE) { | |
237 | skb->pkt_type = PACKET_OTHERHOST; | |
238 | nf_bridge->mask ^= BRNF_PKT_TYPE; | |
239 | } | |
240 | nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING; | |
241 | ||
242 | rt = bridge_parent_rtable(nf_bridge->physindev); | |
243 | if (!rt) { | |
244 | kfree_skb(skb); | |
245 | return 0; | |
246 | } | |
247 | skb_dst_set_noref(skb, &rt->dst); | |
248 | ||
249 | skb->dev = nf_bridge->physindev; | |
250 | nf_bridge_update_protocol(skb); | |
251 | nf_bridge_push_encap_header(skb); | |
252 | NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, | |
253 | br_handle_frame_finish, 1); | |
254 | ||
255 | return 0; | |
256 | } | |
257 | ||
258 | /* Obtain the correct destination MAC address, while preserving the original | |
259 | * source MAC address. If we already know this address, we just copy it. If we | |
260 | * don't, we use the neighbour framework to find out. In both cases, we make | |
261 | * sure that br_handle_frame_finish() is called afterwards. | |
262 | */ | |
263 | static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb) | |
264 | { | |
265 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
266 | struct dst_entry *dst; | |
267 | ||
268 | skb->dev = bridge_parent(skb->dev); | |
269 | if (!skb->dev) | |
270 | goto free_skb; | |
271 | dst = skb_dst(skb); | |
272 | if (dst->hh) { | |
273 | neigh_hh_bridge(dst->hh, skb); | |
274 | skb->dev = nf_bridge->physindev; | |
275 | return br_handle_frame_finish(skb); | |
276 | } else if (dst->neighbour) { | |
277 | /* the neighbour function below overwrites the complete | |
278 | * MAC header, so we save the Ethernet source address and | |
279 | * protocol number. */ | |
280 | skb_copy_from_linear_data_offset(skb, -(ETH_HLEN-ETH_ALEN), skb->nf_bridge->data, ETH_HLEN-ETH_ALEN); | |
281 | /* tell br_dev_xmit to continue with forwarding */ | |
282 | nf_bridge->mask |= BRNF_BRIDGED_DNAT; | |
283 | return dst->neighbour->output(skb); | |
284 | } | |
285 | free_skb: | |
286 | kfree_skb(skb); | |
287 | return 0; | |
288 | } | |
289 | ||
290 | /* This requires some explaining. If DNAT has taken place, | |
291 | * we will need to fix up the destination Ethernet address. | |
292 | * | |
293 | * There are two cases to consider: | |
294 | * 1. The packet was DNAT'ed to a device in the same bridge | |
295 | * port group as it was received on. We can still bridge | |
296 | * the packet. | |
297 | * 2. The packet was DNAT'ed to a different device, either | |
298 | * a non-bridged device or another bridge port group. | |
299 | * The packet will need to be routed. | |
300 | * | |
301 | * The correct way of distinguishing between these two cases is to | |
302 | * call ip_route_input() and to look at skb->dst->dev, which is | |
303 | * changed to the destination device if ip_route_input() succeeds. | |
304 | * | |
305 | * Let's first consider the case that ip_route_input() succeeds: | |
306 | * | |
307 | * If the output device equals the logical bridge device the packet | |
308 | * came in on, we can consider this bridging. The corresponding MAC | |
309 | * address will be obtained in br_nf_pre_routing_finish_bridge. | |
310 | * Otherwise, the packet is considered to be routed and we just | |
311 | * change the destination MAC address so that the packet will | |
312 | * later be passed up to the IP stack to be routed. For a redirected | |
313 | * packet, ip_route_input() will give back the localhost as output device, | |
314 | * which differs from the bridge device. | |
315 | * | |
316 | * Let's now consider the case that ip_route_input() fails: | |
317 | * | |
318 | * This can be because the destination address is martian, in which case | |
319 | * the packet will be dropped. | |
320 | * If IP forwarding is disabled, ip_route_input() will fail, while | |
321 | * ip_route_output_key() can return success. The source | |
322 | * address for ip_route_output_key() is set to zero, so ip_route_output_key() | |
323 | * thinks we're handling a locally generated packet and won't care | |
324 | * if IP forwarding is enabled. If the output device equals the logical bridge | |
325 | * device, we proceed as if ip_route_input() succeeded. If it differs from the | |
326 | * logical bridge port or if ip_route_output_key() fails we drop the packet. | |
327 | */ | |
328 | static int br_nf_pre_routing_finish(struct sk_buff *skb) | |
329 | { | |
330 | struct net_device *dev = skb->dev; | |
331 | struct iphdr *iph = ip_hdr(skb); | |
332 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
333 | struct rtable *rt; | |
334 | int err; | |
335 | ||
336 | if (nf_bridge->mask & BRNF_PKT_TYPE) { | |
337 | skb->pkt_type = PACKET_OTHERHOST; | |
338 | nf_bridge->mask ^= BRNF_PKT_TYPE; | |
339 | } | |
340 | nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING; | |
341 | if (dnat_took_place(skb)) { | |
342 | if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) { | |
343 | struct flowi fl = { | |
344 | .nl_u = { | |
345 | .ip4_u = { | |
346 | .daddr = iph->daddr, | |
347 | .saddr = 0, | |
348 | .tos = RT_TOS(iph->tos) }, | |
349 | }, | |
350 | .proto = 0, | |
351 | }; | |
352 | struct in_device *in_dev = __in_dev_get_rcu(dev); | |
353 | ||
354 | /* If err equals -EHOSTUNREACH the error is due to a | |
355 | * martian destination or due to the fact that | |
356 | * forwarding is disabled. For most martian packets, | |
357 | * ip_route_output_key() will fail. It won't fail for 2 types of | |
358 | * martian destinations: loopback destinations and destination | |
359 | * 0.0.0.0. In both cases the packet will be dropped because the | |
360 | * destination is the loopback device and not the bridge. */ | |
361 | if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev)) | |
362 | goto free_skb; | |
363 | ||
364 | if (!ip_route_output_key(dev_net(dev), &rt, &fl)) { | |
365 | /* - Bridged-and-DNAT'ed traffic doesn't | |
366 | * require ip_forwarding. */ | |
367 | if (((struct dst_entry *)rt)->dev == dev) { | |
368 | skb_dst_set(skb, (struct dst_entry *)rt); | |
369 | goto bridged_dnat; | |
370 | } | |
371 | dst_release((struct dst_entry *)rt); | |
372 | } | |
373 | free_skb: | |
374 | kfree_skb(skb); | |
375 | return 0; | |
376 | } else { | |
377 | if (skb_dst(skb)->dev == dev) { | |
378 | bridged_dnat: | |
379 | skb->dev = nf_bridge->physindev; | |
380 | nf_bridge_update_protocol(skb); | |
381 | nf_bridge_push_encap_header(skb); | |
382 | NF_HOOK_THRESH(NFPROTO_BRIDGE, | |
383 | NF_BR_PRE_ROUTING, | |
384 | skb, skb->dev, NULL, | |
385 | br_nf_pre_routing_finish_bridge, | |
386 | 1); | |
387 | return 0; | |
388 | } | |
389 | memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN); | |
390 | skb->pkt_type = PACKET_HOST; | |
391 | } | |
392 | } else { | |
393 | rt = bridge_parent_rtable(nf_bridge->physindev); | |
394 | if (!rt) { | |
395 | kfree_skb(skb); | |
396 | return 0; | |
397 | } | |
398 | skb_dst_set_noref(skb, &rt->dst); | |
399 | } | |
400 | ||
401 | skb->dev = nf_bridge->physindev; | |
402 | nf_bridge_update_protocol(skb); | |
403 | nf_bridge_push_encap_header(skb); | |
404 | NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, | |
405 | br_handle_frame_finish, 1); | |
406 | ||
407 | return 0; | |
408 | } | |
409 | ||
410 | /* Some common code for IPv4/IPv6 */ | |
411 | static struct net_device *setup_pre_routing(struct sk_buff *skb) | |
412 | { | |
413 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
414 | ||
415 | if (skb->pkt_type == PACKET_OTHERHOST) { | |
416 | skb->pkt_type = PACKET_HOST; | |
417 | nf_bridge->mask |= BRNF_PKT_TYPE; | |
418 | } | |
419 | ||
420 | nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING; | |
421 | nf_bridge->physindev = skb->dev; | |
422 | skb->dev = bridge_parent(skb->dev); | |
423 | if (skb->protocol == htons(ETH_P_8021Q)) | |
424 | nf_bridge->mask |= BRNF_8021Q; | |
425 | else if (skb->protocol == htons(ETH_P_PPP_SES)) | |
426 | nf_bridge->mask |= BRNF_PPPoE; | |
427 | ||
428 | return skb->dev; | |
429 | } | |
430 | ||
431 | /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */ | |
432 | static int check_hbh_len(struct sk_buff *skb) | |
433 | { | |
434 | unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1); | |
435 | u32 pkt_len; | |
436 | const unsigned char *nh = skb_network_header(skb); | |
437 | int off = raw - nh; | |
438 | int len = (raw[1] + 1) << 3; | |
439 | ||
440 | if ((raw + len) - skb->data > skb_headlen(skb)) | |
441 | goto bad; | |
442 | ||
443 | off += 2; | |
444 | len -= 2; | |
445 | ||
446 | while (len > 0) { | |
447 | int optlen = nh[off + 1] + 2; | |
448 | ||
449 | switch (nh[off]) { | |
450 | case IPV6_TLV_PAD0: | |
451 | optlen = 1; | |
452 | break; | |
453 | ||
454 | case IPV6_TLV_PADN: | |
455 | break; | |
456 | ||
457 | case IPV6_TLV_JUMBO: | |
458 | if (nh[off + 1] != 4 || (off & 3) != 2) | |
459 | goto bad; | |
460 | pkt_len = ntohl(*(__be32 *) (nh + off + 2)); | |
461 | if (pkt_len <= IPV6_MAXPLEN || | |
462 | ipv6_hdr(skb)->payload_len) | |
463 | goto bad; | |
464 | if (pkt_len > skb->len - sizeof(struct ipv6hdr)) | |
465 | goto bad; | |
466 | if (pskb_trim_rcsum(skb, | |
467 | pkt_len + sizeof(struct ipv6hdr))) | |
468 | goto bad; | |
469 | nh = skb_network_header(skb); | |
470 | break; | |
471 | default: | |
472 | if (optlen > len) | |
473 | goto bad; | |
474 | break; | |
475 | } | |
476 | off += optlen; | |
477 | len -= optlen; | |
478 | } | |
479 | if (len == 0) | |
480 | return 0; | |
481 | bad: | |
482 | return -1; | |
483 | ||
484 | } | |
485 | ||
486 | /* Replicate the checks that IPv6 does on packet reception and pass the packet | |
487 | * to ip6tables, which doesn't support NAT, so things are fairly simple. */ | |
488 | static unsigned int br_nf_pre_routing_ipv6(unsigned int hook, | |
489 | struct sk_buff *skb, | |
490 | const struct net_device *in, | |
491 | const struct net_device *out, | |
492 | int (*okfn)(struct sk_buff *)) | |
493 | { | |
494 | struct ipv6hdr *hdr; | |
495 | u32 pkt_len; | |
496 | ||
497 | if (skb->len < sizeof(struct ipv6hdr)) | |
498 | goto inhdr_error; | |
499 | ||
500 | if (!pskb_may_pull(skb, sizeof(struct ipv6hdr))) | |
501 | goto inhdr_error; | |
502 | ||
503 | hdr = ipv6_hdr(skb); | |
504 | ||
505 | if (hdr->version != 6) | |
506 | goto inhdr_error; | |
507 | ||
508 | pkt_len = ntohs(hdr->payload_len); | |
509 | ||
510 | if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) { | |
511 | if (pkt_len + sizeof(struct ipv6hdr) > skb->len) | |
512 | goto inhdr_error; | |
513 | if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) | |
514 | goto inhdr_error; | |
515 | } | |
516 | if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb)) | |
517 | goto inhdr_error; | |
518 | ||
519 | nf_bridge_put(skb->nf_bridge); | |
520 | if (!nf_bridge_alloc(skb)) | |
521 | return NF_DROP; | |
522 | if (!setup_pre_routing(skb)) | |
523 | return NF_DROP; | |
524 | ||
525 | skb->protocol = htons(ETH_P_IPV6); | |
526 | NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, | |
527 | br_nf_pre_routing_finish_ipv6); | |
528 | ||
529 | return NF_STOLEN; | |
530 | ||
531 | inhdr_error: | |
532 | return NF_DROP; | |
533 | } | |
534 | ||
535 | /* Direct IPv6 traffic to br_nf_pre_routing_ipv6. | |
536 | * Replicate the checks that IPv4 does on packet reception. | |
537 | * Set skb->dev to the bridge device (i.e. parent of the | |
538 | * receiving device) to make netfilter happy, the REDIRECT | |
539 | * target in particular. Save the original destination IP | |
540 | * address to be able to detect DNAT afterwards. */ | |
541 | static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff *skb, | |
542 | const struct net_device *in, | |
543 | const struct net_device *out, | |
544 | int (*okfn)(struct sk_buff *)) | |
545 | { | |
546 | struct iphdr *iph; | |
547 | __u32 len = nf_bridge_encap_header_len(skb); | |
548 | ||
549 | if (unlikely(!pskb_may_pull(skb, len))) | |
550 | goto out; | |
551 | ||
552 | if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || | |
553 | IS_PPPOE_IPV6(skb)) { | |
554 | #ifdef CONFIG_SYSCTL | |
555 | if (!brnf_call_ip6tables) | |
556 | return NF_ACCEPT; | |
557 | #endif | |
558 | nf_bridge_pull_encap_header_rcsum(skb); | |
559 | return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn); | |
560 | } | |
561 | #ifdef CONFIG_SYSCTL | |
562 | if (!brnf_call_iptables) | |
563 | return NF_ACCEPT; | |
564 | #endif | |
565 | ||
566 | if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb) && | |
567 | !IS_PPPOE_IP(skb)) | |
568 | return NF_ACCEPT; | |
569 | ||
570 | nf_bridge_pull_encap_header_rcsum(skb); | |
571 | ||
572 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) | |
573 | goto inhdr_error; | |
574 | ||
575 | iph = ip_hdr(skb); | |
576 | if (iph->ihl < 5 || iph->version != 4) | |
577 | goto inhdr_error; | |
578 | ||
579 | if (!pskb_may_pull(skb, 4 * iph->ihl)) | |
580 | goto inhdr_error; | |
581 | ||
582 | iph = ip_hdr(skb); | |
583 | if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0) | |
584 | goto inhdr_error; | |
585 | ||
586 | len = ntohs(iph->tot_len); | |
587 | if (skb->len < len || len < 4 * iph->ihl) | |
588 | goto inhdr_error; | |
589 | ||
590 | pskb_trim_rcsum(skb, len); | |
591 | ||
592 | nf_bridge_put(skb->nf_bridge); | |
593 | if (!nf_bridge_alloc(skb)) | |
594 | return NF_DROP; | |
595 | if (!setup_pre_routing(skb)) | |
596 | return NF_DROP; | |
597 | store_orig_dstaddr(skb); | |
598 | skb->protocol = htons(ETH_P_IP); | |
599 | ||
600 | NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL, | |
601 | br_nf_pre_routing_finish); | |
602 | ||
603 | return NF_STOLEN; | |
604 | ||
605 | inhdr_error: | |
606 | // IP_INC_STATS_BH(IpInHdrErrors); | |
607 | out: | |
608 | return NF_DROP; | |
609 | } | |
610 | ||
611 | ||
612 | /* PF_BRIDGE/LOCAL_IN ************************************************/ | |
613 | /* The packet is locally destined, which requires a real | |
614 | * dst_entry, so detach the fake one. On the way up, the | |
615 | * packet would pass through PRE_ROUTING again (which already | |
616 | * took place when the packet entered the bridge), but we | |
617 | * register an IPv4 PRE_ROUTING 'sabotage' hook that will | |
618 | * prevent this from happening. */ | |
619 | static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff *skb, | |
620 | const struct net_device *in, | |
621 | const struct net_device *out, | |
622 | int (*okfn)(struct sk_buff *)) | |
623 | { | |
624 | struct rtable *rt = skb_rtable(skb); | |
625 | ||
626 | if (rt && rt == bridge_parent_rtable(in)) | |
627 | skb_dst_drop(skb); | |
628 | ||
629 | return NF_ACCEPT; | |
630 | } | |
631 | ||
632 | /* PF_BRIDGE/FORWARD *************************************************/ | |
633 | static int br_nf_forward_finish(struct sk_buff *skb) | |
634 | { | |
635 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
636 | struct net_device *in; | |
637 | ||
638 | if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) { | |
639 | in = nf_bridge->physindev; | |
640 | if (nf_bridge->mask & BRNF_PKT_TYPE) { | |
641 | skb->pkt_type = PACKET_OTHERHOST; | |
642 | nf_bridge->mask ^= BRNF_PKT_TYPE; | |
643 | } | |
644 | nf_bridge_update_protocol(skb); | |
645 | } else { | |
646 | in = *((struct net_device **)(skb->cb)); | |
647 | } | |
648 | nf_bridge_push_encap_header(skb); | |
649 | ||
650 | NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, skb, in, | |
651 | skb->dev, br_forward_finish, 1); | |
652 | return 0; | |
653 | } | |
654 | ||
655 | /* This is the 'purely bridged' case. For IP, we pass the packet to | |
656 | * netfilter with indev and outdev set to the bridge device, | |
657 | * but we are still able to filter on the 'real' indev/outdev | |
658 | * because of the physdev module. For ARP, indev and outdev are the | |
659 | * bridge ports. */ | |
660 | static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff *skb, | |
661 | const struct net_device *in, | |
662 | const struct net_device *out, | |
663 | int (*okfn)(struct sk_buff *)) | |
664 | { | |
665 | struct nf_bridge_info *nf_bridge; | |
666 | struct net_device *parent; | |
667 | u_int8_t pf; | |
668 | ||
669 | if (!skb->nf_bridge) | |
670 | return NF_ACCEPT; | |
671 | ||
672 | /* Need exclusive nf_bridge_info since we might have multiple | |
673 | * different physoutdevs. */ | |
674 | if (!nf_bridge_unshare(skb)) | |
675 | return NF_DROP; | |
676 | ||
677 | parent = bridge_parent(out); | |
678 | if (!parent) | |
679 | return NF_DROP; | |
680 | ||
681 | if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) || | |
682 | IS_PPPOE_IP(skb)) | |
683 | pf = PF_INET; | |
684 | else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || | |
685 | IS_PPPOE_IPV6(skb)) | |
686 | pf = PF_INET6; | |
687 | else | |
688 | return NF_ACCEPT; | |
689 | ||
690 | nf_bridge_pull_encap_header(skb); | |
691 | ||
692 | nf_bridge = skb->nf_bridge; | |
693 | if (skb->pkt_type == PACKET_OTHERHOST) { | |
694 | skb->pkt_type = PACKET_HOST; | |
695 | nf_bridge->mask |= BRNF_PKT_TYPE; | |
696 | } | |
697 | ||
698 | /* The physdev module checks on this */ | |
699 | nf_bridge->mask |= BRNF_BRIDGED; | |
700 | nf_bridge->physoutdev = skb->dev; | |
701 | if (pf == PF_INET) | |
702 | skb->protocol = htons(ETH_P_IP); | |
703 | else | |
704 | skb->protocol = htons(ETH_P_IPV6); | |
705 | ||
706 | NF_HOOK(pf, NF_INET_FORWARD, skb, bridge_parent(in), parent, | |
707 | br_nf_forward_finish); | |
708 | ||
709 | return NF_STOLEN; | |
710 | } | |
711 | ||
712 | static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff *skb, | |
713 | const struct net_device *in, | |
714 | const struct net_device *out, | |
715 | int (*okfn)(struct sk_buff *)) | |
716 | { | |
717 | struct net_device **d = (struct net_device **)(skb->cb); | |
718 | ||
719 | #ifdef CONFIG_SYSCTL | |
720 | if (!brnf_call_arptables) | |
721 | return NF_ACCEPT; | |
722 | #endif | |
723 | ||
724 | if (skb->protocol != htons(ETH_P_ARP)) { | |
725 | if (!IS_VLAN_ARP(skb)) | |
726 | return NF_ACCEPT; | |
727 | nf_bridge_pull_encap_header(skb); | |
728 | } | |
729 | ||
730 | if (arp_hdr(skb)->ar_pln != 4) { | |
731 | if (IS_VLAN_ARP(skb)) | |
732 | nf_bridge_push_encap_header(skb); | |
733 | return NF_ACCEPT; | |
734 | } | |
735 | *d = (struct net_device *)in; | |
736 | NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in, | |
737 | (struct net_device *)out, br_nf_forward_finish); | |
738 | ||
739 | return NF_STOLEN; | |
740 | } | |
741 | ||
742 | #if defined(CONFIG_NF_CONNTRACK_IPV4) || defined(CONFIG_NF_CONNTRACK_IPV4_MODULE) | |
743 | static int br_nf_dev_queue_xmit(struct sk_buff *skb) | |
744 | { | |
745 | if (skb->nfct != NULL && skb->protocol == htons(ETH_P_IP) && | |
746 | skb->len + nf_bridge_mtu_reduction(skb) > skb->dev->mtu && | |
747 | !skb_is_gso(skb)) | |
748 | return ip_fragment(skb, br_dev_queue_push_xmit); | |
749 | else | |
750 | return br_dev_queue_push_xmit(skb); | |
751 | } | |
752 | #else | |
753 | static int br_nf_dev_queue_xmit(struct sk_buff *skb) | |
754 | { | |
755 | return br_dev_queue_push_xmit(skb); | |
756 | } | |
757 | #endif | |
758 | ||
759 | /* PF_BRIDGE/POST_ROUTING ********************************************/ | |
760 | static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff *skb, | |
761 | const struct net_device *in, | |
762 | const struct net_device *out, | |
763 | int (*okfn)(struct sk_buff *)) | |
764 | { | |
765 | struct nf_bridge_info *nf_bridge = skb->nf_bridge; | |
766 | struct net_device *realoutdev = bridge_parent(skb->dev); | |
767 | u_int8_t pf; | |
768 | ||
769 | if (!nf_bridge || !(nf_bridge->mask & BRNF_BRIDGED)) | |
770 | return NF_ACCEPT; | |
771 | ||
772 | if (!realoutdev) | |
773 | return NF_DROP; | |
774 | ||
775 | if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb) || | |
776 | IS_PPPOE_IP(skb)) | |
777 | pf = PF_INET; | |
778 | else if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb) || | |
779 | IS_PPPOE_IPV6(skb)) | |
780 | pf = PF_INET6; | |
781 | else | |
782 | return NF_ACCEPT; | |
783 | ||
784 | /* We assume any code from br_dev_queue_push_xmit onwards doesn't care | |
785 | * about the value of skb->pkt_type. */ | |
786 | if (skb->pkt_type == PACKET_OTHERHOST) { | |
787 | skb->pkt_type = PACKET_HOST; | |
788 | nf_bridge->mask |= BRNF_PKT_TYPE; | |
789 | } | |
790 | ||
791 | nf_bridge_pull_encap_header(skb); | |
792 | nf_bridge_save_header(skb); | |
793 | if (pf == PF_INET) | |
794 | skb->protocol = htons(ETH_P_IP); | |
795 | else | |
796 | skb->protocol = htons(ETH_P_IPV6); | |
797 | ||
798 | NF_HOOK(pf, NF_INET_POST_ROUTING, skb, NULL, realoutdev, | |
799 | br_nf_dev_queue_xmit); | |
800 | ||
801 | return NF_STOLEN; | |
802 | } | |
803 | ||
804 | /* IP/SABOTAGE *****************************************************/ | |
805 | /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING | |
806 | * for the second time. */ | |
807 | static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff *skb, | |
808 | const struct net_device *in, | |
809 | const struct net_device *out, | |
810 | int (*okfn)(struct sk_buff *)) | |
811 | { | |
812 | if (skb->nf_bridge && | |
813 | !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) { | |
814 | return NF_STOP; | |
815 | } | |
816 | ||
817 | return NF_ACCEPT; | |
818 | } | |
819 | ||
820 | /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because | |
821 | * br_dev_queue_push_xmit is called afterwards */ | |
822 | static struct nf_hook_ops br_nf_ops[] __read_mostly = { | |
823 | { | |
824 | .hook = br_nf_pre_routing, | |
825 | .owner = THIS_MODULE, | |
826 | .pf = PF_BRIDGE, | |
827 | .hooknum = NF_BR_PRE_ROUTING, | |
828 | .priority = NF_BR_PRI_BRNF, | |
829 | }, | |
830 | { | |
831 | .hook = br_nf_local_in, | |
832 | .owner = THIS_MODULE, | |
833 | .pf = PF_BRIDGE, | |
834 | .hooknum = NF_BR_LOCAL_IN, | |
835 | .priority = NF_BR_PRI_BRNF, | |
836 | }, | |
837 | { | |
838 | .hook = br_nf_forward_ip, | |
839 | .owner = THIS_MODULE, | |
840 | .pf = PF_BRIDGE, | |
841 | .hooknum = NF_BR_FORWARD, | |
842 | .priority = NF_BR_PRI_BRNF - 1, | |
843 | }, | |
844 | { | |
845 | .hook = br_nf_forward_arp, | |
846 | .owner = THIS_MODULE, | |
847 | .pf = PF_BRIDGE, | |
848 | .hooknum = NF_BR_FORWARD, | |
849 | .priority = NF_BR_PRI_BRNF, | |
850 | }, | |
851 | { | |
852 | .hook = br_nf_post_routing, | |
853 | .owner = THIS_MODULE, | |
854 | .pf = PF_BRIDGE, | |
855 | .hooknum = NF_BR_POST_ROUTING, | |
856 | .priority = NF_BR_PRI_LAST, | |
857 | }, | |
858 | { | |
859 | .hook = ip_sabotage_in, | |
860 | .owner = THIS_MODULE, | |
861 | .pf = PF_INET, | |
862 | .hooknum = NF_INET_PRE_ROUTING, | |
863 | .priority = NF_IP_PRI_FIRST, | |
864 | }, | |
865 | { | |
866 | .hook = ip_sabotage_in, | |
867 | .owner = THIS_MODULE, | |
868 | .pf = PF_INET6, | |
869 | .hooknum = NF_INET_PRE_ROUTING, | |
870 | .priority = NF_IP6_PRI_FIRST, | |
871 | }, | |
872 | }; | |
873 | ||
874 | #ifdef CONFIG_SYSCTL | |
875 | static | |
876 | int brnf_sysctl_call_tables(ctl_table * ctl, int write, | |
877 | void __user * buffer, size_t * lenp, loff_t * ppos) | |
878 | { | |
879 | int ret; | |
880 | ||
881 | ret = proc_dointvec(ctl, write, buffer, lenp, ppos); | |
882 | ||
883 | if (write && *(int *)(ctl->data)) | |
884 | *(int *)(ctl->data) = 1; | |
885 | return ret; | |
886 | } | |
887 | ||
888 | static ctl_table brnf_table[] = { | |
889 | { | |
890 | .procname = "bridge-nf-call-arptables", | |
891 | .data = &brnf_call_arptables, | |
892 | .maxlen = sizeof(int), | |
893 | .mode = 0644, | |
894 | .proc_handler = brnf_sysctl_call_tables, | |
895 | }, | |
896 | { | |
897 | .procname = "bridge-nf-call-iptables", | |
898 | .data = &brnf_call_iptables, | |
899 | .maxlen = sizeof(int), | |
900 | .mode = 0644, | |
901 | .proc_handler = brnf_sysctl_call_tables, | |
902 | }, | |
903 | { | |
904 | .procname = "bridge-nf-call-ip6tables", | |
905 | .data = &brnf_call_ip6tables, | |
906 | .maxlen = sizeof(int), | |
907 | .mode = 0644, | |
908 | .proc_handler = brnf_sysctl_call_tables, | |
909 | }, | |
910 | { | |
911 | .procname = "bridge-nf-filter-vlan-tagged", | |
912 | .data = &brnf_filter_vlan_tagged, | |
913 | .maxlen = sizeof(int), | |
914 | .mode = 0644, | |
915 | .proc_handler = brnf_sysctl_call_tables, | |
916 | }, | |
917 | { | |
918 | .procname = "bridge-nf-filter-pppoe-tagged", | |
919 | .data = &brnf_filter_pppoe_tagged, | |
920 | .maxlen = sizeof(int), | |
921 | .mode = 0644, | |
922 | .proc_handler = brnf_sysctl_call_tables, | |
923 | }, | |
924 | { } | |
925 | }; | |
926 | ||
927 | static struct ctl_path brnf_path[] = { | |
928 | { .procname = "net", }, | |
929 | { .procname = "bridge", }, | |
930 | { } | |
931 | }; | |
932 | #endif | |
933 | ||
934 | int __init br_netfilter_init(void) | |
935 | { | |
936 | int ret; | |
937 | ||
938 | ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); | |
939 | if (ret < 0) | |
940 | return ret; | |
941 | #ifdef CONFIG_SYSCTL | |
942 | brnf_sysctl_header = register_sysctl_paths(brnf_path, brnf_table); | |
943 | if (brnf_sysctl_header == NULL) { | |
944 | printk(KERN_WARNING | |
945 | "br_netfilter: can't register to sysctl.\n"); | |
946 | nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); | |
947 | return -ENOMEM; | |
948 | } | |
949 | #endif | |
950 | printk(KERN_NOTICE "Bridge firewalling registered\n"); | |
951 | return 0; | |
952 | } | |
953 | ||
954 | void br_netfilter_fini(void) | |
955 | { | |
956 | nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops)); | |
957 | #ifdef CONFIG_SYSCTL | |
958 | unregister_sysctl_table(brnf_sysctl_header); | |
959 | #endif | |
960 | } |