1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Handle firewalling
4 * Linux ethernet bridge
5 *
6 * Authors:
7 * Lennert Buytenhek <buytenh@gnu.org>
8 * Bart De Schuymer <bdschuym@pandora.be>
9 *
10 * Lennert dedicates this file to Kerstin Wurdinger.
11 */
12
13 #include <linux/module.h>
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/ip.h>
17 #include <linux/netdevice.h>
18 #include <linux/skbuff.h>
19 #include <linux/if_arp.h>
20 #include <linux/if_ether.h>
21 #include <linux/if_vlan.h>
22 #include <linux/if_pppox.h>
23 #include <linux/ppp_defs.h>
24 #include <linux/netfilter_bridge.h>
25 #include <uapi/linux/netfilter_bridge.h>
26 #include <linux/netfilter_ipv4.h>
27 #include <linux/netfilter_ipv6.h>
28 #include <linux/netfilter_arp.h>
29 #include <linux/in_route.h>
30 #include <linux/rculist.h>
31 #include <linux/inetdevice.h>
32
33 #include <net/ip.h>
34 #include <net/ipv6.h>
35 #include <net/addrconf.h>
36 #include <net/route.h>
37 #include <net/netfilter/br_netfilter.h>
38 #include <net/netns/generic.h>
39
40 #include <linux/uaccess.h>
41 #include "br_private.h"
42 #ifdef CONFIG_SYSCTL
43 #include <linux/sysctl.h>
44 #endif
45
46 static unsigned int brnf_net_id __read_mostly;
47
48 struct brnf_net {
49 bool enabled;
50
51 #ifdef CONFIG_SYSCTL
52 struct ctl_table_header *ctl_hdr;
53 #endif
54
55 /* default value is 1 */
56 int call_iptables;
57 int call_ip6tables;
58 int call_arptables;
59
60 /* default value is 0 */
61 int filter_vlan_tagged;
62 int filter_pppoe_tagged;
63 int pass_vlan_indev;
64 };
65
66 #define IS_IP(skb) \
67 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
68
69 #define IS_IPV6(skb) \
70 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
71
72 #define IS_ARP(skb) \
73 (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
74
vlan_proto(const struct sk_buff * skb)75 static inline __be16 vlan_proto(const struct sk_buff *skb)
76 {
77 if (skb_vlan_tag_present(skb))
78 return skb->protocol;
79 else if (skb->protocol == htons(ETH_P_8021Q))
80 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
81 else
82 return 0;
83 }
84
is_vlan_ip(const struct sk_buff * skb,const struct net * net)85 static inline bool is_vlan_ip(const struct sk_buff *skb, const struct net *net)
86 {
87 struct brnf_net *brnet = net_generic(net, brnf_net_id);
88
89 return vlan_proto(skb) == htons(ETH_P_IP) && brnet->filter_vlan_tagged;
90 }
91
is_vlan_ipv6(const struct sk_buff * skb,const struct net * net)92 static inline bool is_vlan_ipv6(const struct sk_buff *skb,
93 const struct net *net)
94 {
95 struct brnf_net *brnet = net_generic(net, brnf_net_id);
96
97 return vlan_proto(skb) == htons(ETH_P_IPV6) &&
98 brnet->filter_vlan_tagged;
99 }
100
is_vlan_arp(const struct sk_buff * skb,const struct net * net)101 static inline bool is_vlan_arp(const struct sk_buff *skb, const struct net *net)
102 {
103 struct brnf_net *brnet = net_generic(net, brnf_net_id);
104
105 return vlan_proto(skb) == htons(ETH_P_ARP) && brnet->filter_vlan_tagged;
106 }
107
pppoe_proto(const struct sk_buff * skb)108 static inline __be16 pppoe_proto(const struct sk_buff *skb)
109 {
110 return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
111 sizeof(struct pppoe_hdr)));
112 }
113
is_pppoe_ip(const struct sk_buff * skb,const struct net * net)114 static inline bool is_pppoe_ip(const struct sk_buff *skb, const struct net *net)
115 {
116 struct brnf_net *brnet = net_generic(net, brnf_net_id);
117
118 return skb->protocol == htons(ETH_P_PPP_SES) &&
119 pppoe_proto(skb) == htons(PPP_IP) && brnet->filter_pppoe_tagged;
120 }
121
is_pppoe_ipv6(const struct sk_buff * skb,const struct net * net)122 static inline bool is_pppoe_ipv6(const struct sk_buff *skb,
123 const struct net *net)
124 {
125 struct brnf_net *brnet = net_generic(net, brnf_net_id);
126
127 return skb->protocol == htons(ETH_P_PPP_SES) &&
128 pppoe_proto(skb) == htons(PPP_IPV6) &&
129 brnet->filter_pppoe_tagged;
130 }
131
132 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
133 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
134
135 struct brnf_frag_data {
136 char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
137 u8 encap_size;
138 u8 size;
139 u16 vlan_tci;
140 __be16 vlan_proto;
141 };
142
143 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
144
nf_bridge_info_free(struct sk_buff * skb)145 static void nf_bridge_info_free(struct sk_buff *skb)
146 {
147 skb_ext_del(skb, SKB_EXT_BRIDGE_NF);
148 }
149
bridge_parent(const struct net_device * dev)150 static inline struct net_device *bridge_parent(const struct net_device *dev)
151 {
152 struct net_bridge_port *port;
153
154 port = br_port_get_rcu(dev);
155 return port ? port->br->dev : NULL;
156 }
157
nf_bridge_unshare(struct sk_buff * skb)158 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
159 {
160 return skb_ext_add(skb, SKB_EXT_BRIDGE_NF);
161 }
162
nf_bridge_encap_header_len(const struct sk_buff * skb)163 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
164 {
165 switch (skb->protocol) {
166 case __cpu_to_be16(ETH_P_8021Q):
167 return VLAN_HLEN;
168 case __cpu_to_be16(ETH_P_PPP_SES):
169 return PPPOE_SES_HLEN;
170 default:
171 return 0;
172 }
173 }
174
nf_bridge_pull_encap_header(struct sk_buff * skb)175 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
176 {
177 unsigned int len = nf_bridge_encap_header_len(skb);
178
179 skb_pull(skb, len);
180 skb->network_header += len;
181 }
182
nf_bridge_pull_encap_header_rcsum(struct sk_buff * skb)183 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
184 {
185 unsigned int len = nf_bridge_encap_header_len(skb);
186
187 skb_pull_rcsum(skb, len);
188 skb->network_header += len;
189 }
190
191 /* When handing a packet over to the IP layer
192 * check whether we have a skb that is in the
193 * expected format
194 */
195
br_validate_ipv4(struct net * net,struct sk_buff * skb)196 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
197 {
198 const struct iphdr *iph;
199 u32 len;
200
201 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
202 goto inhdr_error;
203
204 iph = ip_hdr(skb);
205
206 /* Basic sanity checks */
207 if (iph->ihl < 5 || iph->version != 4)
208 goto inhdr_error;
209
210 if (!pskb_may_pull(skb, iph->ihl*4))
211 goto inhdr_error;
212
213 iph = ip_hdr(skb);
214 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
215 goto csum_error;
216
217 len = ntohs(iph->tot_len);
218 if (skb->len < len) {
219 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
220 goto drop;
221 } else if (len < (iph->ihl*4))
222 goto inhdr_error;
223
224 if (pskb_trim_rcsum(skb, len)) {
225 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
226 goto drop;
227 }
228
229 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
230 /* We should really parse IP options here but until
231 * somebody who actually uses IP options complains to
232 * us we'll just silently ignore the options because
233 * we're lazy!
234 */
235 return 0;
236
237 csum_error:
238 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
239 inhdr_error:
240 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
241 drop:
242 return -1;
243 }
244
nf_bridge_update_protocol(struct sk_buff * skb)245 void nf_bridge_update_protocol(struct sk_buff *skb)
246 {
247 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
248
249 switch (nf_bridge->orig_proto) {
250 case BRNF_PROTO_8021Q:
251 skb->protocol = htons(ETH_P_8021Q);
252 break;
253 case BRNF_PROTO_PPPOE:
254 skb->protocol = htons(ETH_P_PPP_SES);
255 break;
256 case BRNF_PROTO_UNCHANGED:
257 break;
258 }
259 }
260
261 /* Obtain the correct destination MAC address, while preserving the original
262 * source MAC address. If we already know this address, we just copy it. If we
263 * don't, we use the neighbour framework to find out. In both cases, we make
264 * sure that br_handle_frame_finish() is called afterwards.
265 */
br_nf_pre_routing_finish_bridge(struct net * net,struct sock * sk,struct sk_buff * skb)266 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
267 {
268 struct neighbour *neigh;
269 struct dst_entry *dst;
270
271 skb->dev = bridge_parent(skb->dev);
272 if (!skb->dev)
273 goto free_skb;
274 dst = skb_dst(skb);
275 neigh = dst_neigh_lookup_skb(dst, skb);
276 if (neigh) {
277 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
278 int ret;
279
280 if ((neigh->nud_state & NUD_CONNECTED) && neigh->hh.hh_len) {
281 neigh_hh_bridge(&neigh->hh, skb);
282 skb->dev = nf_bridge->physindev;
283 ret = br_handle_frame_finish(net, sk, skb);
284 } else {
285 /* the neighbour function below overwrites the complete
286 * MAC header, so we save the Ethernet source address and
287 * protocol number.
288 */
289 skb_copy_from_linear_data_offset(skb,
290 -(ETH_HLEN-ETH_ALEN),
291 nf_bridge->neigh_header,
292 ETH_HLEN-ETH_ALEN);
293 /* tell br_dev_xmit to continue with forwarding */
294 nf_bridge->bridged_dnat = 1;
295 /* FIXME Need to refragment */
296 ret = neigh->output(neigh, skb);
297 }
298 neigh_release(neigh);
299 return ret;
300 }
301 free_skb:
302 kfree_skb(skb);
303 return 0;
304 }
305
306 static inline bool
br_nf_ipv4_daddr_was_changed(const struct sk_buff * skb,const struct nf_bridge_info * nf_bridge)307 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
308 const struct nf_bridge_info *nf_bridge)
309 {
310 return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
311 }
312
313 /* This requires some explaining. If DNAT has taken place,
314 * we will need to fix up the destination Ethernet address.
315 * This is also true when SNAT takes place (for the reply direction).
316 *
317 * There are two cases to consider:
318 * 1. The packet was DNAT'ed to a device in the same bridge
319 * port group as it was received on. We can still bridge
320 * the packet.
321 * 2. The packet was DNAT'ed to a different device, either
322 * a non-bridged device or another bridge port group.
323 * The packet will need to be routed.
324 *
325 * The correct way of distinguishing between these two cases is to
326 * call ip_route_input() and to look at skb->dst->dev, which is
327 * changed to the destination device if ip_route_input() succeeds.
328 *
329 * Let's first consider the case that ip_route_input() succeeds:
330 *
331 * If the output device equals the logical bridge device the packet
332 * came in on, we can consider this bridging. The corresponding MAC
333 * address will be obtained in br_nf_pre_routing_finish_bridge.
334 * Otherwise, the packet is considered to be routed and we just
335 * change the destination MAC address so that the packet will
336 * later be passed up to the IP stack to be routed. For a redirected
337 * packet, ip_route_input() will give back the localhost as output device,
338 * which differs from the bridge device.
339 *
340 * Let's now consider the case that ip_route_input() fails:
341 *
342 * This can be because the destination address is martian, in which case
343 * the packet will be dropped.
344 * If IP forwarding is disabled, ip_route_input() will fail, while
345 * ip_route_output_key() can return success. The source
346 * address for ip_route_output_key() is set to zero, so ip_route_output_key()
347 * thinks we're handling a locally generated packet and won't care
348 * if IP forwarding is enabled. If the output device equals the logical bridge
349 * device, we proceed as if ip_route_input() succeeded. If it differs from the
350 * logical bridge port or if ip_route_output_key() fails we drop the packet.
351 */
br_nf_pre_routing_finish(struct net * net,struct sock * sk,struct sk_buff * skb)352 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
353 {
354 struct net_device *dev = skb->dev;
355 struct iphdr *iph = ip_hdr(skb);
356 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
357 struct rtable *rt;
358 int err;
359
360 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
361
362 if (nf_bridge->pkt_otherhost) {
363 skb->pkt_type = PACKET_OTHERHOST;
364 nf_bridge->pkt_otherhost = false;
365 }
366 nf_bridge->in_prerouting = 0;
367 if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
368 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
369 struct in_device *in_dev = __in_dev_get_rcu(dev);
370
371 /* If err equals -EHOSTUNREACH the error is due to a
372 * martian destination or due to the fact that
373 * forwarding is disabled. For most martian packets,
374 * ip_route_output_key() will fail. It won't fail for 2 types of
375 * martian destinations: loopback destinations and destination
376 * 0.0.0.0. In both cases the packet will be dropped because the
377 * destination is the loopback device and not the bridge. */
378 if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
379 goto free_skb;
380
381 rt = ip_route_output(net, iph->daddr, 0,
382 RT_TOS(iph->tos), 0);
383 if (!IS_ERR(rt)) {
384 /* - Bridged-and-DNAT'ed traffic doesn't
385 * require ip_forwarding. */
386 if (rt->dst.dev == dev) {
387 skb_dst_set(skb, &rt->dst);
388 goto bridged_dnat;
389 }
390 ip_rt_put(rt);
391 }
392 free_skb:
393 kfree_skb(skb);
394 return 0;
395 } else {
396 if (skb_dst(skb)->dev == dev) {
397 bridged_dnat:
398 skb->dev = nf_bridge->physindev;
399 nf_bridge_update_protocol(skb);
400 nf_bridge_push_encap_header(skb);
401 br_nf_hook_thresh(NF_BR_PRE_ROUTING,
402 net, sk, skb, skb->dev,
403 NULL,
404 br_nf_pre_routing_finish_bridge);
405 return 0;
406 }
407 ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
408 skb->pkt_type = PACKET_HOST;
409 }
410 } else {
411 rt = bridge_parent_rtable(nf_bridge->physindev);
412 if (!rt) {
413 kfree_skb(skb);
414 return 0;
415 }
416 skb_dst_set_noref(skb, &rt->dst);
417 }
418
419 skb->dev = nf_bridge->physindev;
420 nf_bridge_update_protocol(skb);
421 nf_bridge_push_encap_header(skb);
422 br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL,
423 br_handle_frame_finish);
424 return 0;
425 }
426
brnf_get_logical_dev(struct sk_buff * skb,const struct net_device * dev,const struct net * net)427 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb,
428 const struct net_device *dev,
429 const struct net *net)
430 {
431 struct net_device *vlan, *br;
432 struct brnf_net *brnet = net_generic(net, brnf_net_id);
433
434 br = bridge_parent(dev);
435
436 if (brnet->pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
437 return br;
438
439 vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
440 skb_vlan_tag_get(skb) & VLAN_VID_MASK);
441
442 return vlan ? vlan : br;
443 }
444
445 /* Some common code for IPv4/IPv6 */
setup_pre_routing(struct sk_buff * skb,const struct net * net)446 struct net_device *setup_pre_routing(struct sk_buff *skb, const struct net *net)
447 {
448 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
449
450 if (skb->pkt_type == PACKET_OTHERHOST) {
451 skb->pkt_type = PACKET_HOST;
452 nf_bridge->pkt_otherhost = true;
453 }
454
455 nf_bridge->in_prerouting = 1;
456 nf_bridge->physindev = skb->dev;
457 skb->dev = brnf_get_logical_dev(skb, skb->dev, net);
458
459 if (skb->protocol == htons(ETH_P_8021Q))
460 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
461 else if (skb->protocol == htons(ETH_P_PPP_SES))
462 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
463
464 /* Must drop socket now because of tproxy. */
465 skb_orphan(skb);
466 return skb->dev;
467 }
468
469 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
470 * Replicate the checks that IPv4 does on packet reception.
471 * Set skb->dev to the bridge device (i.e. parent of the
472 * receiving device) to make netfilter happy, the REDIRECT
473 * target in particular. Save the original destination IP
474 * address to be able to detect DNAT afterwards. */
br_nf_pre_routing(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)475 static unsigned int br_nf_pre_routing(void *priv,
476 struct sk_buff *skb,
477 const struct nf_hook_state *state)
478 {
479 struct nf_bridge_info *nf_bridge;
480 struct net_bridge_port *p;
481 struct net_bridge *br;
482 __u32 len = nf_bridge_encap_header_len(skb);
483 struct brnf_net *brnet;
484
485 if (unlikely(!pskb_may_pull(skb, len)))
486 return NF_DROP;
487
488 p = br_port_get_rcu(state->in);
489 if (p == NULL)
490 return NF_DROP;
491 br = p->br;
492
493 brnet = net_generic(state->net, brnf_net_id);
494 if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
495 is_pppoe_ipv6(skb, state->net)) {
496 if (!brnet->call_ip6tables &&
497 !br_opt_get(br, BROPT_NF_CALL_IP6TABLES))
498 return NF_ACCEPT;
499 if (!ipv6_mod_enabled()) {
500 pr_warn_once("Module ipv6 is disabled, so call_ip6tables is not supported.");
501 return NF_DROP;
502 }
503
504 nf_bridge_pull_encap_header_rcsum(skb);
505 return br_nf_pre_routing_ipv6(priv, skb, state);
506 }
507
508 if (!brnet->call_iptables && !br_opt_get(br, BROPT_NF_CALL_IPTABLES))
509 return NF_ACCEPT;
510
511 if (!IS_IP(skb) && !is_vlan_ip(skb, state->net) &&
512 !is_pppoe_ip(skb, state->net))
513 return NF_ACCEPT;
514
515 nf_bridge_pull_encap_header_rcsum(skb);
516
517 if (br_validate_ipv4(state->net, skb))
518 return NF_DROP;
519
520 if (!nf_bridge_alloc(skb))
521 return NF_DROP;
522 if (!setup_pre_routing(skb, state->net))
523 return NF_DROP;
524
525 nf_bridge = nf_bridge_info_get(skb);
526 nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
527
528 skb->protocol = htons(ETH_P_IP);
529 skb->transport_header = skb->network_header + ip_hdr(skb)->ihl * 4;
530
531 NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
532 skb->dev, NULL,
533 br_nf_pre_routing_finish);
534
535 return NF_STOLEN;
536 }
537
538
539 /* PF_BRIDGE/FORWARD *************************************************/
br_nf_forward_finish(struct net * net,struct sock * sk,struct sk_buff * skb)540 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
541 {
542 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
543 struct net_device *in;
544
545 if (!IS_ARP(skb) && !is_vlan_arp(skb, net)) {
546
547 if (skb->protocol == htons(ETH_P_IP))
548 nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
549
550 if (skb->protocol == htons(ETH_P_IPV6))
551 nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
552
553 in = nf_bridge->physindev;
554 if (nf_bridge->pkt_otherhost) {
555 skb->pkt_type = PACKET_OTHERHOST;
556 nf_bridge->pkt_otherhost = false;
557 }
558 nf_bridge_update_protocol(skb);
559 } else {
560 in = *((struct net_device **)(skb->cb));
561 }
562 nf_bridge_push_encap_header(skb);
563
564 br_nf_hook_thresh(NF_BR_FORWARD, net, sk, skb, in, skb->dev,
565 br_forward_finish);
566 return 0;
567 }
568
569
570 /* This is the 'purely bridged' case. For IP, we pass the packet to
571 * netfilter with indev and outdev set to the bridge device,
572 * but we are still able to filter on the 'real' indev/outdev
573 * because of the physdev module. For ARP, indev and outdev are the
574 * bridge ports. */
br_nf_forward_ip(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)575 static unsigned int br_nf_forward_ip(void *priv,
576 struct sk_buff *skb,
577 const struct nf_hook_state *state)
578 {
579 struct nf_bridge_info *nf_bridge;
580 struct net_device *parent;
581 u_int8_t pf;
582
583 nf_bridge = nf_bridge_info_get(skb);
584 if (!nf_bridge)
585 return NF_ACCEPT;
586
587 /* Need exclusive nf_bridge_info since we might have multiple
588 * different physoutdevs. */
589 if (!nf_bridge_unshare(skb))
590 return NF_DROP;
591
592 nf_bridge = nf_bridge_info_get(skb);
593 if (!nf_bridge)
594 return NF_DROP;
595
596 parent = bridge_parent(state->out);
597 if (!parent)
598 return NF_DROP;
599
600 if (IS_IP(skb) || is_vlan_ip(skb, state->net) ||
601 is_pppoe_ip(skb, state->net))
602 pf = NFPROTO_IPV4;
603 else if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
604 is_pppoe_ipv6(skb, state->net))
605 pf = NFPROTO_IPV6;
606 else
607 return NF_ACCEPT;
608
609 nf_bridge_pull_encap_header(skb);
610
611 if (skb->pkt_type == PACKET_OTHERHOST) {
612 skb->pkt_type = PACKET_HOST;
613 nf_bridge->pkt_otherhost = true;
614 }
615
616 if (pf == NFPROTO_IPV4) {
617 if (br_validate_ipv4(state->net, skb))
618 return NF_DROP;
619 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
620 }
621
622 if (pf == NFPROTO_IPV6) {
623 if (br_validate_ipv6(state->net, skb))
624 return NF_DROP;
625 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
626 }
627
628 nf_bridge->physoutdev = skb->dev;
629 if (pf == NFPROTO_IPV4)
630 skb->protocol = htons(ETH_P_IP);
631 else
632 skb->protocol = htons(ETH_P_IPV6);
633
634 NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
635 brnf_get_logical_dev(skb, state->in, state->net),
636 parent, br_nf_forward_finish);
637
638 return NF_STOLEN;
639 }
640
br_nf_forward_arp(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)641 static unsigned int br_nf_forward_arp(void *priv,
642 struct sk_buff *skb,
643 const struct nf_hook_state *state)
644 {
645 struct net_bridge_port *p;
646 struct net_bridge *br;
647 struct net_device **d = (struct net_device **)(skb->cb);
648 struct brnf_net *brnet;
649
650 p = br_port_get_rcu(state->out);
651 if (p == NULL)
652 return NF_ACCEPT;
653 br = p->br;
654
655 brnet = net_generic(state->net, brnf_net_id);
656 if (!brnet->call_arptables && !br_opt_get(br, BROPT_NF_CALL_ARPTABLES))
657 return NF_ACCEPT;
658
659 if (!IS_ARP(skb)) {
660 if (!is_vlan_arp(skb, state->net))
661 return NF_ACCEPT;
662 nf_bridge_pull_encap_header(skb);
663 }
664
665 if (unlikely(!pskb_may_pull(skb, sizeof(struct arphdr))))
666 return NF_DROP;
667
668 if (arp_hdr(skb)->ar_pln != 4) {
669 if (is_vlan_arp(skb, state->net))
670 nf_bridge_push_encap_header(skb);
671 return NF_ACCEPT;
672 }
673 *d = state->in;
674 NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
675 state->in, state->out, br_nf_forward_finish);
676
677 return NF_STOLEN;
678 }
679
br_nf_push_frag_xmit(struct net * net,struct sock * sk,struct sk_buff * skb)680 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
681 {
682 struct brnf_frag_data *data;
683 int err;
684
685 data = this_cpu_ptr(&brnf_frag_data_storage);
686 err = skb_cow_head(skb, data->size);
687
688 if (err) {
689 kfree_skb(skb);
690 return 0;
691 }
692
693 if (data->vlan_proto)
694 __vlan_hwaccel_put_tag(skb, data->vlan_proto, data->vlan_tci);
695
696 skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
697 __skb_push(skb, data->encap_size);
698
699 nf_bridge_info_free(skb);
700 return br_dev_queue_push_xmit(net, sk, skb);
701 }
702
703 static int
br_nf_ip_fragment(struct net * net,struct sock * sk,struct sk_buff * skb,int (* output)(struct net *,struct sock *,struct sk_buff *))704 br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
705 int (*output)(struct net *, struct sock *, struct sk_buff *))
706 {
707 unsigned int mtu = ip_skb_dst_mtu(sk, skb);
708 struct iphdr *iph = ip_hdr(skb);
709
710 if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
711 (IPCB(skb)->frag_max_size &&
712 IPCB(skb)->frag_max_size > mtu))) {
713 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
714 kfree_skb(skb);
715 return -EMSGSIZE;
716 }
717
718 return ip_do_fragment(net, sk, skb, output);
719 }
720
nf_bridge_mtu_reduction(const struct sk_buff * skb)721 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
722 {
723 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
724
725 if (nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
726 return PPPOE_SES_HLEN;
727 return 0;
728 }
729
br_nf_dev_queue_xmit(struct net * net,struct sock * sk,struct sk_buff * skb)730 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
731 {
732 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
733 unsigned int mtu, mtu_reserved;
734
735 mtu_reserved = nf_bridge_mtu_reduction(skb);
736 mtu = skb->dev->mtu;
737
738 if (nf_bridge->frag_max_size && nf_bridge->frag_max_size < mtu)
739 mtu = nf_bridge->frag_max_size;
740
741 if (skb_is_gso(skb) || skb->len + mtu_reserved <= mtu) {
742 nf_bridge_info_free(skb);
743 return br_dev_queue_push_xmit(net, sk, skb);
744 }
745
746 /* This is wrong! We should preserve the original fragment
747 * boundaries by preserving frag_list rather than refragmenting.
748 */
749 if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
750 skb->protocol == htons(ETH_P_IP)) {
751 struct brnf_frag_data *data;
752
753 if (br_validate_ipv4(net, skb))
754 goto drop;
755
756 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
757
758 nf_bridge_update_protocol(skb);
759
760 data = this_cpu_ptr(&brnf_frag_data_storage);
761
762 if (skb_vlan_tag_present(skb)) {
763 data->vlan_tci = skb->vlan_tci;
764 data->vlan_proto = skb->vlan_proto;
765 } else {
766 data->vlan_proto = 0;
767 }
768
769 data->encap_size = nf_bridge_encap_header_len(skb);
770 data->size = ETH_HLEN + data->encap_size;
771
772 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
773 data->size);
774
775 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
776 }
777 if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
778 skb->protocol == htons(ETH_P_IPV6)) {
779 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
780 struct brnf_frag_data *data;
781
782 if (br_validate_ipv6(net, skb))
783 goto drop;
784
785 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
786
787 nf_bridge_update_protocol(skb);
788
789 data = this_cpu_ptr(&brnf_frag_data_storage);
790 data->encap_size = nf_bridge_encap_header_len(skb);
791 data->size = ETH_HLEN + data->encap_size;
792
793 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
794 data->size);
795
796 if (v6ops)
797 return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
798
799 kfree_skb(skb);
800 return -EMSGSIZE;
801 }
802 nf_bridge_info_free(skb);
803 return br_dev_queue_push_xmit(net, sk, skb);
804 drop:
805 kfree_skb(skb);
806 return 0;
807 }
808
809 /* PF_BRIDGE/POST_ROUTING ********************************************/
br_nf_post_routing(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)810 static unsigned int br_nf_post_routing(void *priv,
811 struct sk_buff *skb,
812 const struct nf_hook_state *state)
813 {
814 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
815 struct net_device *realoutdev = bridge_parent(skb->dev);
816 u_int8_t pf;
817
818 /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
819 * on a bridge, but was delivered locally and is now being routed:
820 *
821 * POST_ROUTING was already invoked from the ip stack.
822 */
823 if (!nf_bridge || !nf_bridge->physoutdev)
824 return NF_ACCEPT;
825
826 if (!realoutdev)
827 return NF_DROP;
828
829 if (IS_IP(skb) || is_vlan_ip(skb, state->net) ||
830 is_pppoe_ip(skb, state->net))
831 pf = NFPROTO_IPV4;
832 else if (IS_IPV6(skb) || is_vlan_ipv6(skb, state->net) ||
833 is_pppoe_ipv6(skb, state->net))
834 pf = NFPROTO_IPV6;
835 else
836 return NF_ACCEPT;
837
838 /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
839 * about the value of skb->pkt_type. */
840 if (skb->pkt_type == PACKET_OTHERHOST) {
841 skb->pkt_type = PACKET_HOST;
842 nf_bridge->pkt_otherhost = true;
843 }
844
845 nf_bridge_pull_encap_header(skb);
846 if (pf == NFPROTO_IPV4)
847 skb->protocol = htons(ETH_P_IP);
848 else
849 skb->protocol = htons(ETH_P_IPV6);
850
851 NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
852 NULL, realoutdev,
853 br_nf_dev_queue_xmit);
854
855 return NF_STOLEN;
856 }
857
858 /* IP/SABOTAGE *****************************************************/
859 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
860 * for the second time. */
ip_sabotage_in(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)861 static unsigned int ip_sabotage_in(void *priv,
862 struct sk_buff *skb,
863 const struct nf_hook_state *state)
864 {
865 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
866
867 if (nf_bridge && !nf_bridge->in_prerouting &&
868 !netif_is_l3_master(skb->dev) &&
869 !netif_is_l3_slave(skb->dev)) {
870 state->okfn(state->net, state->sk, skb);
871 return NF_STOLEN;
872 }
873
874 return NF_ACCEPT;
875 }
876
877 /* This is called when br_netfilter has called into iptables/netfilter,
878 * and DNAT has taken place on a bridge-forwarded packet.
879 *
880 * neigh->output has created a new MAC header, with local br0 MAC
881 * as saddr.
882 *
883 * This restores the original MAC saddr of the bridged packet
884 * before invoking bridge forward logic to transmit the packet.
885 */
br_nf_pre_routing_finish_bridge_slow(struct sk_buff * skb)886 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
887 {
888 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
889
890 skb_pull(skb, ETH_HLEN);
891 nf_bridge->bridged_dnat = 0;
892
893 BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
894
895 skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
896 nf_bridge->neigh_header,
897 ETH_HLEN - ETH_ALEN);
898 skb->dev = nf_bridge->physindev;
899
900 nf_bridge->physoutdev = NULL;
901 br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
902 }
903
br_nf_dev_xmit(struct sk_buff * skb)904 static int br_nf_dev_xmit(struct sk_buff *skb)
905 {
906 const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
907
908 if (nf_bridge && nf_bridge->bridged_dnat) {
909 br_nf_pre_routing_finish_bridge_slow(skb);
910 return 1;
911 }
912 return 0;
913 }
914
915 static const struct nf_br_ops br_ops = {
916 .br_dev_xmit_hook = br_nf_dev_xmit,
917 };
918
919 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
920 * br_dev_queue_push_xmit is called afterwards */
921 static const struct nf_hook_ops br_nf_ops[] = {
922 {
923 .hook = br_nf_pre_routing,
924 .pf = NFPROTO_BRIDGE,
925 .hooknum = NF_BR_PRE_ROUTING,
926 .priority = NF_BR_PRI_BRNF,
927 },
928 {
929 .hook = br_nf_forward_ip,
930 .pf = NFPROTO_BRIDGE,
931 .hooknum = NF_BR_FORWARD,
932 .priority = NF_BR_PRI_BRNF - 1,
933 },
934 {
935 .hook = br_nf_forward_arp,
936 .pf = NFPROTO_BRIDGE,
937 .hooknum = NF_BR_FORWARD,
938 .priority = NF_BR_PRI_BRNF,
939 },
940 {
941 .hook = br_nf_post_routing,
942 .pf = NFPROTO_BRIDGE,
943 .hooknum = NF_BR_POST_ROUTING,
944 .priority = NF_BR_PRI_LAST,
945 },
946 {
947 .hook = ip_sabotage_in,
948 .pf = NFPROTO_IPV4,
949 .hooknum = NF_INET_PRE_ROUTING,
950 .priority = NF_IP_PRI_FIRST,
951 },
952 {
953 .hook = ip_sabotage_in,
954 .pf = NFPROTO_IPV6,
955 .hooknum = NF_INET_PRE_ROUTING,
956 .priority = NF_IP6_PRI_FIRST,
957 },
958 };
959
brnf_device_event(struct notifier_block * unused,unsigned long event,void * ptr)960 static int brnf_device_event(struct notifier_block *unused, unsigned long event,
961 void *ptr)
962 {
963 struct net_device *dev = netdev_notifier_info_to_dev(ptr);
964 struct brnf_net *brnet;
965 struct net *net;
966 int ret;
967
968 if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
969 return NOTIFY_DONE;
970
971 ASSERT_RTNL();
972
973 net = dev_net(dev);
974 brnet = net_generic(net, brnf_net_id);
975 if (brnet->enabled)
976 return NOTIFY_OK;
977
978 ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
979 if (ret)
980 return NOTIFY_BAD;
981
982 brnet->enabled = true;
983 return NOTIFY_OK;
984 }
985
986 static struct notifier_block brnf_notifier __read_mostly = {
987 .notifier_call = brnf_device_event,
988 };
989
990 /* recursively invokes nf_hook_slow (again), skipping already-called
991 * hooks (< NF_BR_PRI_BRNF).
992 *
993 * Called with rcu read lock held.
994 */
br_nf_hook_thresh(unsigned int hook,struct net * net,struct sock * sk,struct sk_buff * skb,struct net_device * indev,struct net_device * outdev,int (* okfn)(struct net *,struct sock *,struct sk_buff *))995 int br_nf_hook_thresh(unsigned int hook, struct net *net,
996 struct sock *sk, struct sk_buff *skb,
997 struct net_device *indev,
998 struct net_device *outdev,
999 int (*okfn)(struct net *, struct sock *,
1000 struct sk_buff *))
1001 {
1002 const struct nf_hook_entries *e;
1003 struct nf_hook_state state;
1004 struct nf_hook_ops **ops;
1005 unsigned int i;
1006 int ret;
1007
1008 e = rcu_dereference(net->nf.hooks_bridge[hook]);
1009 if (!e)
1010 return okfn(net, sk, skb);
1011
1012 ops = nf_hook_entries_get_hook_ops(e);
1013 for (i = 0; i < e->num_hook_entries &&
1014 ops[i]->priority <= NF_BR_PRI_BRNF; i++)
1015 ;
1016
1017 nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
1018 sk, net, okfn);
1019
1020 ret = nf_hook_slow(skb, &state, e, i);
1021 if (ret == 1)
1022 ret = okfn(net, sk, skb);
1023
1024 return ret;
1025 }
1026
1027 #ifdef CONFIG_SYSCTL
1028 static
brnf_sysctl_call_tables(struct ctl_table * ctl,int write,void __user * buffer,size_t * lenp,loff_t * ppos)1029 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
1030 void __user *buffer, size_t *lenp, loff_t *ppos)
1031 {
1032 int ret;
1033
1034 ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1035
1036 if (write && *(int *)(ctl->data))
1037 *(int *)(ctl->data) = 1;
1038 return ret;
1039 }
1040
1041 static struct ctl_table brnf_table[] = {
1042 {
1043 .procname = "bridge-nf-call-arptables",
1044 .maxlen = sizeof(int),
1045 .mode = 0644,
1046 .proc_handler = brnf_sysctl_call_tables,
1047 },
1048 {
1049 .procname = "bridge-nf-call-iptables",
1050 .maxlen = sizeof(int),
1051 .mode = 0644,
1052 .proc_handler = brnf_sysctl_call_tables,
1053 },
1054 {
1055 .procname = "bridge-nf-call-ip6tables",
1056 .maxlen = sizeof(int),
1057 .mode = 0644,
1058 .proc_handler = brnf_sysctl_call_tables,
1059 },
1060 {
1061 .procname = "bridge-nf-filter-vlan-tagged",
1062 .maxlen = sizeof(int),
1063 .mode = 0644,
1064 .proc_handler = brnf_sysctl_call_tables,
1065 },
1066 {
1067 .procname = "bridge-nf-filter-pppoe-tagged",
1068 .maxlen = sizeof(int),
1069 .mode = 0644,
1070 .proc_handler = brnf_sysctl_call_tables,
1071 },
1072 {
1073 .procname = "bridge-nf-pass-vlan-input-dev",
1074 .maxlen = sizeof(int),
1075 .mode = 0644,
1076 .proc_handler = brnf_sysctl_call_tables,
1077 },
1078 { }
1079 };
1080
br_netfilter_sysctl_default(struct brnf_net * brnf)1081 static inline void br_netfilter_sysctl_default(struct brnf_net *brnf)
1082 {
1083 brnf->call_iptables = 1;
1084 brnf->call_ip6tables = 1;
1085 brnf->call_arptables = 1;
1086 brnf->filter_vlan_tagged = 0;
1087 brnf->filter_pppoe_tagged = 0;
1088 brnf->pass_vlan_indev = 0;
1089 }
1090
br_netfilter_sysctl_init_net(struct net * net)1091 static int br_netfilter_sysctl_init_net(struct net *net)
1092 {
1093 struct ctl_table *table = brnf_table;
1094 struct brnf_net *brnet;
1095
1096 if (!net_eq(net, &init_net)) {
1097 table = kmemdup(table, sizeof(brnf_table), GFP_KERNEL);
1098 if (!table)
1099 return -ENOMEM;
1100 }
1101
1102 brnet = net_generic(net, brnf_net_id);
1103 table[0].data = &brnet->call_arptables;
1104 table[1].data = &brnet->call_iptables;
1105 table[2].data = &brnet->call_ip6tables;
1106 table[3].data = &brnet->filter_vlan_tagged;
1107 table[4].data = &brnet->filter_pppoe_tagged;
1108 table[5].data = &brnet->pass_vlan_indev;
1109
1110 br_netfilter_sysctl_default(brnet);
1111
1112 brnet->ctl_hdr = register_net_sysctl(net, "net/bridge", table);
1113 if (!brnet->ctl_hdr) {
1114 if (!net_eq(net, &init_net))
1115 kfree(table);
1116
1117 return -ENOMEM;
1118 }
1119
1120 return 0;
1121 }
1122
br_netfilter_sysctl_exit_net(struct net * net,struct brnf_net * brnet)1123 static void br_netfilter_sysctl_exit_net(struct net *net,
1124 struct brnf_net *brnet)
1125 {
1126 struct ctl_table *table = brnet->ctl_hdr->ctl_table_arg;
1127
1128 unregister_net_sysctl_table(brnet->ctl_hdr);
1129 if (!net_eq(net, &init_net))
1130 kfree(table);
1131 }
1132
brnf_init_net(struct net * net)1133 static int __net_init brnf_init_net(struct net *net)
1134 {
1135 return br_netfilter_sysctl_init_net(net);
1136 }
1137 #endif
1138
brnf_exit_net(struct net * net)1139 static void __net_exit brnf_exit_net(struct net *net)
1140 {
1141 struct brnf_net *brnet;
1142
1143 brnet = net_generic(net, brnf_net_id);
1144 if (brnet->enabled) {
1145 nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
1146 brnet->enabled = false;
1147 }
1148
1149 #ifdef CONFIG_SYSCTL
1150 br_netfilter_sysctl_exit_net(net, brnet);
1151 #endif
1152 }
1153
1154 static struct pernet_operations brnf_net_ops __read_mostly = {
1155 #ifdef CONFIG_SYSCTL
1156 .init = brnf_init_net,
1157 #endif
1158 .exit = brnf_exit_net,
1159 .id = &brnf_net_id,
1160 .size = sizeof(struct brnf_net),
1161 };
1162
br_netfilter_init(void)1163 static int __init br_netfilter_init(void)
1164 {
1165 int ret;
1166
1167 ret = register_pernet_subsys(&brnf_net_ops);
1168 if (ret < 0)
1169 return ret;
1170
1171 ret = register_netdevice_notifier(&brnf_notifier);
1172 if (ret < 0) {
1173 unregister_pernet_subsys(&brnf_net_ops);
1174 return ret;
1175 }
1176
1177 RCU_INIT_POINTER(nf_br_ops, &br_ops);
1178 printk(KERN_NOTICE "Bridge firewalling registered\n");
1179 return 0;
1180 }
1181
br_netfilter_fini(void)1182 static void __exit br_netfilter_fini(void)
1183 {
1184 RCU_INIT_POINTER(nf_br_ops, NULL);
1185 unregister_netdevice_notifier(&brnf_notifier);
1186 unregister_pernet_subsys(&brnf_net_ops);
1187 }
1188
1189 module_init(br_netfilter_init);
1190 module_exit(br_netfilter_fini);
1191
1192 MODULE_LICENSE("GPL");
1193 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1194 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1195 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
1196