Merge branches 'arm/rockchip', 'arm/exynos', 'arm/smmu', 'x86/vt-d', 'x86/amd', ...
[sfrench/cifs-2.6.git] / 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                <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 #include <net/netfilter/br_netfilter.h>
39
40 #include <asm/uaccess.h>
41 #include "br_private.h"
42 #ifdef CONFIG_SYSCTL
43 #include <linux/sysctl.h>
44 #endif
45
46 #ifdef CONFIG_SYSCTL
47 static struct ctl_table_header *brnf_sysctl_header;
48 static int brnf_call_iptables __read_mostly = 1;
49 static int brnf_call_ip6tables __read_mostly = 1;
50 static int brnf_call_arptables __read_mostly = 1;
51 static int brnf_filter_vlan_tagged __read_mostly = 0;
52 static int brnf_filter_pppoe_tagged __read_mostly = 0;
53 static int brnf_pass_vlan_indev __read_mostly = 0;
54 #else
55 #define brnf_call_iptables 1
56 #define brnf_call_ip6tables 1
57 #define brnf_call_arptables 1
58 #define brnf_filter_vlan_tagged 0
59 #define brnf_filter_pppoe_tagged 0
60 #define brnf_pass_vlan_indev 0
61 #endif
62
63 #define IS_IP(skb) \
64         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
65
66 #define IS_IPV6(skb) \
67         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
68
69 #define IS_ARP(skb) \
70         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
71
72 static inline __be16 vlan_proto(const struct sk_buff *skb)
73 {
74         if (skb_vlan_tag_present(skb))
75                 return skb->protocol;
76         else if (skb->protocol == htons(ETH_P_8021Q))
77                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
78         else
79                 return 0;
80 }
81
82 #define IS_VLAN_IP(skb) \
83         (vlan_proto(skb) == htons(ETH_P_IP) && \
84          brnf_filter_vlan_tagged)
85
86 #define IS_VLAN_IPV6(skb) \
87         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
88          brnf_filter_vlan_tagged)
89
90 #define IS_VLAN_ARP(skb) \
91         (vlan_proto(skb) == htons(ETH_P_ARP) && \
92          brnf_filter_vlan_tagged)
93
94 static inline __be16 pppoe_proto(const struct sk_buff *skb)
95 {
96         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
97                             sizeof(struct pppoe_hdr)));
98 }
99
100 #define IS_PPPOE_IP(skb) \
101         (skb->protocol == htons(ETH_P_PPP_SES) && \
102          pppoe_proto(skb) == htons(PPP_IP) && \
103          brnf_filter_pppoe_tagged)
104
105 #define IS_PPPOE_IPV6(skb) \
106         (skb->protocol == htons(ETH_P_PPP_SES) && \
107          pppoe_proto(skb) == htons(PPP_IPV6) && \
108          brnf_filter_pppoe_tagged)
109
110 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
111 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
112
113 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
114 struct brnf_frag_data {
115         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
116         u8 encap_size;
117         u8 size;
118 };
119
120 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
121 #endif
122
123 static struct nf_bridge_info *nf_bridge_info_get(const struct sk_buff *skb)
124 {
125         return skb->nf_bridge;
126 }
127
128 static inline struct rtable *bridge_parent_rtable(const struct net_device *dev)
129 {
130         struct net_bridge_port *port;
131
132         port = br_port_get_rcu(dev);
133         return port ? &port->br->fake_rtable : NULL;
134 }
135
136 static inline struct net_device *bridge_parent(const struct net_device *dev)
137 {
138         struct net_bridge_port *port;
139
140         port = br_port_get_rcu(dev);
141         return port ? port->br->dev : NULL;
142 }
143
144 static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
145 {
146         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
147         if (likely(skb->nf_bridge))
148                 atomic_set(&(skb->nf_bridge->use), 1);
149
150         return skb->nf_bridge;
151 }
152
153 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
154 {
155         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
156
157         if (atomic_read(&nf_bridge->use) > 1) {
158                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
159
160                 if (tmp) {
161                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
162                         atomic_set(&tmp->use, 1);
163                 }
164                 nf_bridge_put(nf_bridge);
165                 nf_bridge = tmp;
166         }
167         return nf_bridge;
168 }
169
170 static unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
171 {
172         switch (skb->protocol) {
173         case __cpu_to_be16(ETH_P_8021Q):
174                 return VLAN_HLEN;
175         case __cpu_to_be16(ETH_P_PPP_SES):
176                 return PPPOE_SES_HLEN;
177         default:
178                 return 0;
179         }
180 }
181
182 static inline void nf_bridge_push_encap_header(struct sk_buff *skb)
183 {
184         unsigned int len = nf_bridge_encap_header_len(skb);
185
186         skb_push(skb, len);
187         skb->network_header -= len;
188 }
189
190 static inline void nf_bridge_pull_encap_header(struct sk_buff *skb)
191 {
192         unsigned int len = nf_bridge_encap_header_len(skb);
193
194         skb_pull(skb, len);
195         skb->network_header += len;
196 }
197
198 static inline void nf_bridge_pull_encap_header_rcsum(struct sk_buff *skb)
199 {
200         unsigned int len = nf_bridge_encap_header_len(skb);
201
202         skb_pull_rcsum(skb, len);
203         skb->network_header += len;
204 }
205
206 /* When handing a packet over to the IP layer
207  * check whether we have a skb that is in the
208  * expected format
209  */
210
211 static int br_parse_ip_options(struct sk_buff *skb)
212 {
213         const struct iphdr *iph;
214         struct net_device *dev = skb->dev;
215         u32 len;
216
217         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
218                 goto inhdr_error;
219
220         iph = ip_hdr(skb);
221
222         /* Basic sanity checks */
223         if (iph->ihl < 5 || iph->version != 4)
224                 goto inhdr_error;
225
226         if (!pskb_may_pull(skb, iph->ihl*4))
227                 goto inhdr_error;
228
229         iph = ip_hdr(skb);
230         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
231                 goto inhdr_error;
232
233         len = ntohs(iph->tot_len);
234         if (skb->len < len) {
235                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INTRUNCATEDPKTS);
236                 goto drop;
237         } else if (len < (iph->ihl*4))
238                 goto inhdr_error;
239
240         if (pskb_trim_rcsum(skb, len)) {
241                 IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
242                 goto drop;
243         }
244
245         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
246         /* We should really parse IP options here but until
247          * somebody who actually uses IP options complains to
248          * us we'll just silently ignore the options because
249          * we're lazy!
250          */
251         return 0;
252
253 inhdr_error:
254         IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
255 drop:
256         return -1;
257 }
258
259 static void nf_bridge_update_protocol(struct sk_buff *skb)
260 {
261         switch (skb->nf_bridge->orig_proto) {
262         case BRNF_PROTO_8021Q:
263                 skb->protocol = htons(ETH_P_8021Q);
264                 break;
265         case BRNF_PROTO_PPPOE:
266                 skb->protocol = htons(ETH_P_PPP_SES);
267                 break;
268         case BRNF_PROTO_UNCHANGED:
269                 break;
270         }
271 }
272
273 /* PF_BRIDGE/PRE_ROUTING *********************************************/
274 /* Undo the changes made for ip6tables PREROUTING and continue the
275  * bridge PRE_ROUTING hook. */
276 static int br_nf_pre_routing_finish_ipv6(struct sock *sk, struct sk_buff *skb)
277 {
278         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
279         struct rtable *rt;
280
281         if (nf_bridge->pkt_otherhost) {
282                 skb->pkt_type = PACKET_OTHERHOST;
283                 nf_bridge->pkt_otherhost = false;
284         }
285         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
286
287         rt = bridge_parent_rtable(nf_bridge->physindev);
288         if (!rt) {
289                 kfree_skb(skb);
290                 return 0;
291         }
292         skb_dst_set_noref(skb, &rt->dst);
293
294         skb->dev = nf_bridge->physindev;
295         nf_bridge_update_protocol(skb);
296         nf_bridge_push_encap_header(skb);
297         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
298                        skb->dev, NULL,
299                        br_handle_frame_finish, 1);
300
301         return 0;
302 }
303
304 /* Obtain the correct destination MAC address, while preserving the original
305  * source MAC address. If we already know this address, we just copy it. If we
306  * don't, we use the neighbour framework to find out. In both cases, we make
307  * sure that br_handle_frame_finish() is called afterwards.
308  */
309 static int br_nf_pre_routing_finish_bridge(struct sock *sk, struct sk_buff *skb)
310 {
311         struct neighbour *neigh;
312         struct dst_entry *dst;
313
314         skb->dev = bridge_parent(skb->dev);
315         if (!skb->dev)
316                 goto free_skb;
317         dst = skb_dst(skb);
318         neigh = dst_neigh_lookup_skb(dst, skb);
319         if (neigh) {
320                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
321                 int ret;
322
323                 if (neigh->hh.hh_len) {
324                         neigh_hh_bridge(&neigh->hh, skb);
325                         skb->dev = nf_bridge->physindev;
326                         ret = br_handle_frame_finish(sk, skb);
327                 } else {
328                         /* the neighbour function below overwrites the complete
329                          * MAC header, so we save the Ethernet source address and
330                          * protocol number.
331                          */
332                         skb_copy_from_linear_data_offset(skb,
333                                                          -(ETH_HLEN-ETH_ALEN),
334                                                          nf_bridge->neigh_header,
335                                                          ETH_HLEN-ETH_ALEN);
336                         /* tell br_dev_xmit to continue with forwarding */
337                         nf_bridge->mask |= BRNF_BRIDGED_DNAT;
338                         /* FIXME Need to refragment */
339                         ret = neigh->output(neigh, skb);
340                 }
341                 neigh_release(neigh);
342                 return ret;
343         }
344 free_skb:
345         kfree_skb(skb);
346         return 0;
347 }
348
349 static bool daddr_was_changed(const struct sk_buff *skb,
350                               const struct nf_bridge_info *nf_bridge)
351 {
352         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
353 }
354
355 /* This requires some explaining. If DNAT has taken place,
356  * we will need to fix up the destination Ethernet address.
357  * This is also true when SNAT takes place (for the reply direction).
358  *
359  * There are two cases to consider:
360  * 1. The packet was DNAT'ed to a device in the same bridge
361  *    port group as it was received on. We can still bridge
362  *    the packet.
363  * 2. The packet was DNAT'ed to a different device, either
364  *    a non-bridged device or another bridge port group.
365  *    The packet will need to be routed.
366  *
367  * The correct way of distinguishing between these two cases is to
368  * call ip_route_input() and to look at skb->dst->dev, which is
369  * changed to the destination device if ip_route_input() succeeds.
370  *
371  * Let's first consider the case that ip_route_input() succeeds:
372  *
373  * If the output device equals the logical bridge device the packet
374  * came in on, we can consider this bridging. The corresponding MAC
375  * address will be obtained in br_nf_pre_routing_finish_bridge.
376  * Otherwise, the packet is considered to be routed and we just
377  * change the destination MAC address so that the packet will
378  * later be passed up to the IP stack to be routed. For a redirected
379  * packet, ip_route_input() will give back the localhost as output device,
380  * which differs from the bridge device.
381  *
382  * Let's now consider the case that ip_route_input() fails:
383  *
384  * This can be because the destination address is martian, in which case
385  * the packet will be dropped.
386  * If IP forwarding is disabled, ip_route_input() will fail, while
387  * ip_route_output_key() can return success. The source
388  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
389  * thinks we're handling a locally generated packet and won't care
390  * if IP forwarding is enabled. If the output device equals the logical bridge
391  * device, we proceed as if ip_route_input() succeeded. If it differs from the
392  * logical bridge port or if ip_route_output_key() fails we drop the packet.
393  */
394 static int br_nf_pre_routing_finish(struct sock *sk, struct sk_buff *skb)
395 {
396         struct net_device *dev = skb->dev;
397         struct iphdr *iph = ip_hdr(skb);
398         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
399         struct rtable *rt;
400         int err;
401         int frag_max_size;
402
403         frag_max_size = IPCB(skb)->frag_max_size;
404         BR_INPUT_SKB_CB(skb)->frag_max_size = frag_max_size;
405
406         if (nf_bridge->pkt_otherhost) {
407                 skb->pkt_type = PACKET_OTHERHOST;
408                 nf_bridge->pkt_otherhost = false;
409         }
410         nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
411         if (daddr_was_changed(skb, nf_bridge)) {
412                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
413                         struct in_device *in_dev = __in_dev_get_rcu(dev);
414
415                         /* If err equals -EHOSTUNREACH the error is due to a
416                          * martian destination or due to the fact that
417                          * forwarding is disabled. For most martian packets,
418                          * ip_route_output_key() will fail. It won't fail for 2 types of
419                          * martian destinations: loopback destinations and destination
420                          * 0.0.0.0. In both cases the packet will be dropped because the
421                          * destination is the loopback device and not the bridge. */
422                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
423                                 goto free_skb;
424
425                         rt = ip_route_output(dev_net(dev), iph->daddr, 0,
426                                              RT_TOS(iph->tos), 0);
427                         if (!IS_ERR(rt)) {
428                                 /* - Bridged-and-DNAT'ed traffic doesn't
429                                  *   require ip_forwarding. */
430                                 if (rt->dst.dev == dev) {
431                                         skb_dst_set(skb, &rt->dst);
432                                         goto bridged_dnat;
433                                 }
434                                 ip_rt_put(rt);
435                         }
436 free_skb:
437                         kfree_skb(skb);
438                         return 0;
439                 } else {
440                         if (skb_dst(skb)->dev == dev) {
441 bridged_dnat:
442                                 skb->dev = nf_bridge->physindev;
443                                 nf_bridge_update_protocol(skb);
444                                 nf_bridge_push_encap_header(skb);
445                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
446                                                NF_BR_PRE_ROUTING,
447                                                sk, skb, skb->dev, NULL,
448                                                br_nf_pre_routing_finish_bridge,
449                                                1);
450                                 return 0;
451                         }
452                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
453                         skb->pkt_type = PACKET_HOST;
454                 }
455         } else {
456                 rt = bridge_parent_rtable(nf_bridge->physindev);
457                 if (!rt) {
458                         kfree_skb(skb);
459                         return 0;
460                 }
461                 skb_dst_set_noref(skb, &rt->dst);
462         }
463
464         skb->dev = nf_bridge->physindev;
465         nf_bridge_update_protocol(skb);
466         nf_bridge_push_encap_header(skb);
467         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, sk, skb,
468                        skb->dev, NULL,
469                        br_handle_frame_finish, 1);
470
471         return 0;
472 }
473
474 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
475 {
476         struct net_device *vlan, *br;
477
478         br = bridge_parent(dev);
479         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
480                 return br;
481
482         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
483                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
484
485         return vlan ? vlan : br;
486 }
487
488 /* Some common code for IPv4/IPv6 */
489 static struct net_device *setup_pre_routing(struct sk_buff *skb)
490 {
491         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
492
493         if (skb->pkt_type == PACKET_OTHERHOST) {
494                 skb->pkt_type = PACKET_HOST;
495                 nf_bridge->pkt_otherhost = true;
496         }
497
498         nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
499         nf_bridge->physindev = skb->dev;
500         skb->dev = brnf_get_logical_dev(skb, skb->dev);
501
502         if (skb->protocol == htons(ETH_P_8021Q))
503                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
504         else if (skb->protocol == htons(ETH_P_PPP_SES))
505                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
506
507         /* Must drop socket now because of tproxy. */
508         skb_orphan(skb);
509         return skb->dev;
510 }
511
512 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
513 static int check_hbh_len(struct sk_buff *skb)
514 {
515         unsigned char *raw = (u8 *)(ipv6_hdr(skb) + 1);
516         u32 pkt_len;
517         const unsigned char *nh = skb_network_header(skb);
518         int off = raw - nh;
519         int len = (raw[1] + 1) << 3;
520
521         if ((raw + len) - skb->data > skb_headlen(skb))
522                 goto bad;
523
524         off += 2;
525         len -= 2;
526
527         while (len > 0) {
528                 int optlen = nh[off + 1] + 2;
529
530                 switch (nh[off]) {
531                 case IPV6_TLV_PAD1:
532                         optlen = 1;
533                         break;
534
535                 case IPV6_TLV_PADN:
536                         break;
537
538                 case IPV6_TLV_JUMBO:
539                         if (nh[off + 1] != 4 || (off & 3) != 2)
540                                 goto bad;
541                         pkt_len = ntohl(*(__be32 *) (nh + off + 2));
542                         if (pkt_len <= IPV6_MAXPLEN ||
543                             ipv6_hdr(skb)->payload_len)
544                                 goto bad;
545                         if (pkt_len > skb->len - sizeof(struct ipv6hdr))
546                                 goto bad;
547                         if (pskb_trim_rcsum(skb,
548                                             pkt_len + sizeof(struct ipv6hdr)))
549                                 goto bad;
550                         nh = skb_network_header(skb);
551                         break;
552                 default:
553                         if (optlen > len)
554                                 goto bad;
555                         break;
556                 }
557                 off += optlen;
558                 len -= optlen;
559         }
560         if (len == 0)
561                 return 0;
562 bad:
563         return -1;
564
565 }
566
567 /* Replicate the checks that IPv6 does on packet reception and pass the packet
568  * to ip6tables, which doesn't support NAT, so things are fairly simple. */
569 static unsigned int br_nf_pre_routing_ipv6(const struct nf_hook_ops *ops,
570                                            struct sk_buff *skb,
571                                            const struct nf_hook_state *state)
572 {
573         const struct ipv6hdr *hdr;
574         u32 pkt_len;
575
576         if (skb->len < sizeof(struct ipv6hdr))
577                 return NF_DROP;
578
579         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
580                 return NF_DROP;
581
582         hdr = ipv6_hdr(skb);
583
584         if (hdr->version != 6)
585                 return NF_DROP;
586
587         pkt_len = ntohs(hdr->payload_len);
588
589         if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
590                 if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
591                         return NF_DROP;
592                 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
593                         return NF_DROP;
594         }
595         if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
596                 return NF_DROP;
597
598         nf_bridge_put(skb->nf_bridge);
599         if (!nf_bridge_alloc(skb))
600                 return NF_DROP;
601         if (!setup_pre_routing(skb))
602                 return NF_DROP;
603
604         skb->protocol = htons(ETH_P_IPV6);
605         NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, state->sk, skb,
606                 skb->dev, NULL,
607                 br_nf_pre_routing_finish_ipv6);
608
609         return NF_STOLEN;
610 }
611
612 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
613  * Replicate the checks that IPv4 does on packet reception.
614  * Set skb->dev to the bridge device (i.e. parent of the
615  * receiving device) to make netfilter happy, the REDIRECT
616  * target in particular.  Save the original destination IP
617  * address to be able to detect DNAT afterwards. */
618 static unsigned int br_nf_pre_routing(const struct nf_hook_ops *ops,
619                                       struct sk_buff *skb,
620                                       const struct nf_hook_state *state)
621 {
622         struct nf_bridge_info *nf_bridge;
623         struct net_bridge_port *p;
624         struct net_bridge *br;
625         __u32 len = nf_bridge_encap_header_len(skb);
626
627         if (unlikely(!pskb_may_pull(skb, len)))
628                 return NF_DROP;
629
630         p = br_port_get_rcu(state->in);
631         if (p == NULL)
632                 return NF_DROP;
633         br = p->br;
634
635         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
636                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
637                         return NF_ACCEPT;
638
639                 nf_bridge_pull_encap_header_rcsum(skb);
640                 return br_nf_pre_routing_ipv6(ops, skb, state);
641         }
642
643         if (!brnf_call_iptables && !br->nf_call_iptables)
644                 return NF_ACCEPT;
645
646         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
647                 return NF_ACCEPT;
648
649         nf_bridge_pull_encap_header_rcsum(skb);
650
651         if (br_parse_ip_options(skb))
652                 return NF_DROP;
653
654         nf_bridge_put(skb->nf_bridge);
655         if (!nf_bridge_alloc(skb))
656                 return NF_DROP;
657         if (!setup_pre_routing(skb))
658                 return NF_DROP;
659
660         nf_bridge = nf_bridge_info_get(skb);
661         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
662
663         skb->protocol = htons(ETH_P_IP);
664
665         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->sk, skb,
666                 skb->dev, NULL,
667                 br_nf_pre_routing_finish);
668
669         return NF_STOLEN;
670 }
671
672
673 /* PF_BRIDGE/LOCAL_IN ************************************************/
674 /* The packet is locally destined, which requires a real
675  * dst_entry, so detach the fake one.  On the way up, the
676  * packet would pass through PRE_ROUTING again (which already
677  * took place when the packet entered the bridge), but we
678  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
679  * prevent this from happening. */
680 static unsigned int br_nf_local_in(const struct nf_hook_ops *ops,
681                                    struct sk_buff *skb,
682                                    const struct nf_hook_state *state)
683 {
684         br_drop_fake_rtable(skb);
685         return NF_ACCEPT;
686 }
687
688 /* PF_BRIDGE/FORWARD *************************************************/
689 static int br_nf_forward_finish(struct sock *sk, struct sk_buff *skb)
690 {
691         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
692         struct net_device *in;
693
694         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
695                 int frag_max_size;
696
697                 if (skb->protocol == htons(ETH_P_IP)) {
698                         frag_max_size = IPCB(skb)->frag_max_size;
699                         BR_INPUT_SKB_CB(skb)->frag_max_size = frag_max_size;
700                 }
701
702                 in = nf_bridge->physindev;
703                 if (nf_bridge->pkt_otherhost) {
704                         skb->pkt_type = PACKET_OTHERHOST;
705                         nf_bridge->pkt_otherhost = false;
706                 }
707                 nf_bridge_update_protocol(skb);
708         } else {
709                 in = *((struct net_device **)(skb->cb));
710         }
711         nf_bridge_push_encap_header(skb);
712
713         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, sk, skb,
714                        in, skb->dev, br_forward_finish, 1);
715         return 0;
716 }
717
718
719 /* This is the 'purely bridged' case.  For IP, we pass the packet to
720  * netfilter with indev and outdev set to the bridge device,
721  * but we are still able to filter on the 'real' indev/outdev
722  * because of the physdev module. For ARP, indev and outdev are the
723  * bridge ports. */
724 static unsigned int br_nf_forward_ip(const struct nf_hook_ops *ops,
725                                      struct sk_buff *skb,
726                                      const struct nf_hook_state *state)
727 {
728         struct nf_bridge_info *nf_bridge;
729         struct net_device *parent;
730         u_int8_t pf;
731
732         if (!skb->nf_bridge)
733                 return NF_ACCEPT;
734
735         /* Need exclusive nf_bridge_info since we might have multiple
736          * different physoutdevs. */
737         if (!nf_bridge_unshare(skb))
738                 return NF_DROP;
739
740         nf_bridge = nf_bridge_info_get(skb);
741         if (!nf_bridge)
742                 return NF_DROP;
743
744         parent = bridge_parent(state->out);
745         if (!parent)
746                 return NF_DROP;
747
748         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
749                 pf = NFPROTO_IPV4;
750         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
751                 pf = NFPROTO_IPV6;
752         else
753                 return NF_ACCEPT;
754
755         nf_bridge_pull_encap_header(skb);
756
757         if (skb->pkt_type == PACKET_OTHERHOST) {
758                 skb->pkt_type = PACKET_HOST;
759                 nf_bridge->pkt_otherhost = true;
760         }
761
762         if (pf == NFPROTO_IPV4) {
763                 int frag_max = BR_INPUT_SKB_CB(skb)->frag_max_size;
764
765                 if (br_parse_ip_options(skb))
766                         return NF_DROP;
767
768                 IPCB(skb)->frag_max_size = frag_max;
769         }
770
771         nf_bridge->physoutdev = skb->dev;
772         if (pf == NFPROTO_IPV4)
773                 skb->protocol = htons(ETH_P_IP);
774         else
775                 skb->protocol = htons(ETH_P_IPV6);
776
777         NF_HOOK(pf, NF_INET_FORWARD, NULL, skb,
778                 brnf_get_logical_dev(skb, state->in),
779                 parent, br_nf_forward_finish);
780
781         return NF_STOLEN;
782 }
783
784 static unsigned int br_nf_forward_arp(const struct nf_hook_ops *ops,
785                                       struct sk_buff *skb,
786                                       const struct nf_hook_state *state)
787 {
788         struct net_bridge_port *p;
789         struct net_bridge *br;
790         struct net_device **d = (struct net_device **)(skb->cb);
791
792         p = br_port_get_rcu(state->out);
793         if (p == NULL)
794                 return NF_ACCEPT;
795         br = p->br;
796
797         if (!brnf_call_arptables && !br->nf_call_arptables)
798                 return NF_ACCEPT;
799
800         if (!IS_ARP(skb)) {
801                 if (!IS_VLAN_ARP(skb))
802                         return NF_ACCEPT;
803                 nf_bridge_pull_encap_header(skb);
804         }
805
806         if (arp_hdr(skb)->ar_pln != 4) {
807                 if (IS_VLAN_ARP(skb))
808                         nf_bridge_push_encap_header(skb);
809                 return NF_ACCEPT;
810         }
811         *d = state->in;
812         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->sk, skb,
813                 state->in, state->out, br_nf_forward_finish);
814
815         return NF_STOLEN;
816 }
817
818 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
819 static int br_nf_push_frag_xmit(struct sock *sk, struct sk_buff *skb)
820 {
821         struct brnf_frag_data *data;
822         int err;
823
824         data = this_cpu_ptr(&brnf_frag_data_storage);
825         err = skb_cow_head(skb, data->size);
826
827         if (err) {
828                 kfree_skb(skb);
829                 return 0;
830         }
831
832         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
833         __skb_push(skb, data->encap_size);
834
835         return br_dev_queue_push_xmit(sk, skb);
836 }
837
838 static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
839 {
840         int ret;
841         int frag_max_size;
842         unsigned int mtu_reserved;
843
844         if (skb_is_gso(skb) || skb->protocol != htons(ETH_P_IP))
845                 return br_dev_queue_push_xmit(sk, skb);
846
847         mtu_reserved = nf_bridge_mtu_reduction(skb);
848         /* This is wrong! We should preserve the original fragment
849          * boundaries by preserving frag_list rather than refragmenting.
850          */
851         if (skb->len + mtu_reserved > skb->dev->mtu) {
852                 struct brnf_frag_data *data;
853
854                 frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
855                 if (br_parse_ip_options(skb))
856                         /* Drop invalid packet */
857                         return NF_DROP;
858                 IPCB(skb)->frag_max_size = frag_max_size;
859
860                 nf_bridge_update_protocol(skb);
861
862                 data = this_cpu_ptr(&brnf_frag_data_storage);
863                 data->encap_size = nf_bridge_encap_header_len(skb);
864                 data->size = ETH_HLEN + data->encap_size;
865
866                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
867                                                  data->size);
868
869                 ret = ip_fragment(sk, skb, br_nf_push_frag_xmit);
870         } else {
871                 ret = br_dev_queue_push_xmit(sk, skb);
872         }
873
874         return ret;
875 }
876 #else
877 static int br_nf_dev_queue_xmit(struct sock *sk, struct sk_buff *skb)
878 {
879         return br_dev_queue_push_xmit(sk, skb);
880 }
881 #endif
882
883 /* PF_BRIDGE/POST_ROUTING ********************************************/
884 static unsigned int br_nf_post_routing(const struct nf_hook_ops *ops,
885                                        struct sk_buff *skb,
886                                        const struct nf_hook_state *state)
887 {
888         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
889         struct net_device *realoutdev = bridge_parent(skb->dev);
890         u_int8_t pf;
891
892         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
893          * on a bridge, but was delivered locally and is now being routed:
894          *
895          * POST_ROUTING was already invoked from the ip stack.
896          */
897         if (!nf_bridge || !nf_bridge->physoutdev)
898                 return NF_ACCEPT;
899
900         if (!realoutdev)
901                 return NF_DROP;
902
903         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
904                 pf = NFPROTO_IPV4;
905         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
906                 pf = NFPROTO_IPV6;
907         else
908                 return NF_ACCEPT;
909
910         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
911          * about the value of skb->pkt_type. */
912         if (skb->pkt_type == PACKET_OTHERHOST) {
913                 skb->pkt_type = PACKET_HOST;
914                 nf_bridge->pkt_otherhost = true;
915         }
916
917         nf_bridge_pull_encap_header(skb);
918         if (pf == NFPROTO_IPV4)
919                 skb->protocol = htons(ETH_P_IP);
920         else
921                 skb->protocol = htons(ETH_P_IPV6);
922
923         NF_HOOK(pf, NF_INET_POST_ROUTING, state->sk, skb,
924                 NULL, realoutdev,
925                 br_nf_dev_queue_xmit);
926
927         return NF_STOLEN;
928 }
929
930 /* IP/SABOTAGE *****************************************************/
931 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
932  * for the second time. */
933 static unsigned int ip_sabotage_in(const struct nf_hook_ops *ops,
934                                    struct sk_buff *skb,
935                                    const struct nf_hook_state *state)
936 {
937         if (skb->nf_bridge &&
938             !(skb->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
939                 return NF_STOP;
940         }
941
942         return NF_ACCEPT;
943 }
944
945 /* This is called when br_netfilter has called into iptables/netfilter,
946  * and DNAT has taken place on a bridge-forwarded packet.
947  *
948  * neigh->output has created a new MAC header, with local br0 MAC
949  * as saddr.
950  *
951  * This restores the original MAC saddr of the bridged packet
952  * before invoking bridge forward logic to transmit the packet.
953  */
954 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
955 {
956         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
957
958         skb_pull(skb, ETH_HLEN);
959         nf_bridge->mask &= ~BRNF_BRIDGED_DNAT;
960
961         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
962
963         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
964                                        nf_bridge->neigh_header,
965                                        ETH_HLEN - ETH_ALEN);
966         skb->dev = nf_bridge->physindev;
967         br_handle_frame_finish(NULL, skb);
968 }
969
970 static int br_nf_dev_xmit(struct sk_buff *skb)
971 {
972         if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
973                 br_nf_pre_routing_finish_bridge_slow(skb);
974                 return 1;
975         }
976         return 0;
977 }
978
979 static const struct nf_br_ops br_ops = {
980         .br_dev_xmit_hook =     br_nf_dev_xmit,
981 };
982
983 void br_netfilter_enable(void)
984 {
985 }
986 EXPORT_SYMBOL_GPL(br_netfilter_enable);
987
988 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
989  * br_dev_queue_push_xmit is called afterwards */
990 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
991         {
992                 .hook = br_nf_pre_routing,
993                 .owner = THIS_MODULE,
994                 .pf = NFPROTO_BRIDGE,
995                 .hooknum = NF_BR_PRE_ROUTING,
996                 .priority = NF_BR_PRI_BRNF,
997         },
998         {
999                 .hook = br_nf_local_in,
1000                 .owner = THIS_MODULE,
1001                 .pf = NFPROTO_BRIDGE,
1002                 .hooknum = NF_BR_LOCAL_IN,
1003                 .priority = NF_BR_PRI_BRNF,
1004         },
1005         {
1006                 .hook = br_nf_forward_ip,
1007                 .owner = THIS_MODULE,
1008                 .pf = NFPROTO_BRIDGE,
1009                 .hooknum = NF_BR_FORWARD,
1010                 .priority = NF_BR_PRI_BRNF - 1,
1011         },
1012         {
1013                 .hook = br_nf_forward_arp,
1014                 .owner = THIS_MODULE,
1015                 .pf = NFPROTO_BRIDGE,
1016                 .hooknum = NF_BR_FORWARD,
1017                 .priority = NF_BR_PRI_BRNF,
1018         },
1019         {
1020                 .hook = br_nf_post_routing,
1021                 .owner = THIS_MODULE,
1022                 .pf = NFPROTO_BRIDGE,
1023                 .hooknum = NF_BR_POST_ROUTING,
1024                 .priority = NF_BR_PRI_LAST,
1025         },
1026         {
1027                 .hook = ip_sabotage_in,
1028                 .owner = THIS_MODULE,
1029                 .pf = NFPROTO_IPV4,
1030                 .hooknum = NF_INET_PRE_ROUTING,
1031                 .priority = NF_IP_PRI_FIRST,
1032         },
1033         {
1034                 .hook = ip_sabotage_in,
1035                 .owner = THIS_MODULE,
1036                 .pf = NFPROTO_IPV6,
1037                 .hooknum = NF_INET_PRE_ROUTING,
1038                 .priority = NF_IP6_PRI_FIRST,
1039         },
1040 };
1041
1042 #ifdef CONFIG_SYSCTL
1043 static
1044 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
1045                             void __user *buffer, size_t *lenp, loff_t *ppos)
1046 {
1047         int ret;
1048
1049         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1050
1051         if (write && *(int *)(ctl->data))
1052                 *(int *)(ctl->data) = 1;
1053         return ret;
1054 }
1055
1056 static struct ctl_table brnf_table[] = {
1057         {
1058                 .procname       = "bridge-nf-call-arptables",
1059                 .data           = &brnf_call_arptables,
1060                 .maxlen         = sizeof(int),
1061                 .mode           = 0644,
1062                 .proc_handler   = brnf_sysctl_call_tables,
1063         },
1064         {
1065                 .procname       = "bridge-nf-call-iptables",
1066                 .data           = &brnf_call_iptables,
1067                 .maxlen         = sizeof(int),
1068                 .mode           = 0644,
1069                 .proc_handler   = brnf_sysctl_call_tables,
1070         },
1071         {
1072                 .procname       = "bridge-nf-call-ip6tables",
1073                 .data           = &brnf_call_ip6tables,
1074                 .maxlen         = sizeof(int),
1075                 .mode           = 0644,
1076                 .proc_handler   = brnf_sysctl_call_tables,
1077         },
1078         {
1079                 .procname       = "bridge-nf-filter-vlan-tagged",
1080                 .data           = &brnf_filter_vlan_tagged,
1081                 .maxlen         = sizeof(int),
1082                 .mode           = 0644,
1083                 .proc_handler   = brnf_sysctl_call_tables,
1084         },
1085         {
1086                 .procname       = "bridge-nf-filter-pppoe-tagged",
1087                 .data           = &brnf_filter_pppoe_tagged,
1088                 .maxlen         = sizeof(int),
1089                 .mode           = 0644,
1090                 .proc_handler   = brnf_sysctl_call_tables,
1091         },
1092         {
1093                 .procname       = "bridge-nf-pass-vlan-input-dev",
1094                 .data           = &brnf_pass_vlan_indev,
1095                 .maxlen         = sizeof(int),
1096                 .mode           = 0644,
1097                 .proc_handler   = brnf_sysctl_call_tables,
1098         },
1099         { }
1100 };
1101 #endif
1102
1103 static int __init br_netfilter_init(void)
1104 {
1105         int ret;
1106
1107         ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1108         if (ret < 0)
1109                 return ret;
1110
1111 #ifdef CONFIG_SYSCTL
1112         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1113         if (brnf_sysctl_header == NULL) {
1114                 printk(KERN_WARNING
1115                        "br_netfilter: can't register to sysctl.\n");
1116                 nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1117                 return -ENOMEM;
1118         }
1119 #endif
1120         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1121         printk(KERN_NOTICE "Bridge firewalling registered\n");
1122         return 0;
1123 }
1124
1125 static void __exit br_netfilter_fini(void)
1126 {
1127         RCU_INIT_POINTER(nf_br_ops, NULL);
1128         nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
1129 #ifdef CONFIG_SYSCTL
1130         unregister_net_sysctl_table(brnf_sysctl_header);
1131 #endif
1132 }
1133
1134 module_init(br_netfilter_init);
1135 module_exit(br_netfilter_fini);
1136
1137 MODULE_LICENSE("GPL");
1138 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1139 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1140 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");