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TOMOYO Linux Cross Reference
Linux/net/bridge/br_netfilter_hooks.c

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  1 /*
  2  *      Handle firewalling
  3  *      Linux ethernet bridge
  4  *
  5  *      Authors:
  6  *      Lennert Buytenhek               <buytenh@gnu.org>
  7  *      Bart De Schuymer                <bdschuym@pandora.be>
  8  *
  9  *      This program is free software; you can redistribute it and/or
 10  *      modify it under the terms of the GNU General Public License
 11  *      as published by the Free Software Foundation; either version
 12  *      2 of the License, or (at your option) any later version.
 13  *
 14  *      Lennert dedicates this file to Kerstin Wurdinger.
 15  */
 16 
 17 #include <linux/module.h>
 18 #include <linux/kernel.h>
 19 #include <linux/slab.h>
 20 #include <linux/ip.h>
 21 #include <linux/netdevice.h>
 22 #include <linux/skbuff.h>
 23 #include <linux/if_arp.h>
 24 #include <linux/if_ether.h>
 25 #include <linux/if_vlan.h>
 26 #include <linux/if_pppox.h>
 27 #include <linux/ppp_defs.h>
 28 #include <linux/netfilter_bridge.h>
 29 #include <linux/netfilter_ipv4.h>
 30 #include <linux/netfilter_ipv6.h>
 31 #include <linux/netfilter_arp.h>
 32 #include <linux/in_route.h>
 33 #include <linux/inetdevice.h>
 34 
 35 #include <net/ip.h>
 36 #include <net/ipv6.h>
 37 #include <net/addrconf.h>
 38 #include <net/route.h>
 39 #include <net/netfilter/br_netfilter.h>
 40 #include <net/netns/generic.h>
 41 
 42 #include <asm/uaccess.h>
 43 #include "br_private.h"
 44 #ifdef CONFIG_SYSCTL
 45 #include <linux/sysctl.h>
 46 #endif
 47 
 48 static int brnf_net_id __read_mostly;
 49 
 50 struct brnf_net {
 51         bool enabled;
 52 };
 53 
 54 #ifdef CONFIG_SYSCTL
 55 static struct ctl_table_header *brnf_sysctl_header;
 56 static int brnf_call_iptables __read_mostly = 1;
 57 static int brnf_call_ip6tables __read_mostly = 1;
 58 static int brnf_call_arptables __read_mostly = 1;
 59 static int brnf_filter_vlan_tagged __read_mostly;
 60 static int brnf_filter_pppoe_tagged __read_mostly;
 61 static int brnf_pass_vlan_indev __read_mostly;
 62 #else
 63 #define brnf_call_iptables 1
 64 #define brnf_call_ip6tables 1
 65 #define brnf_call_arptables 1
 66 #define brnf_filter_vlan_tagged 0
 67 #define brnf_filter_pppoe_tagged 0
 68 #define brnf_pass_vlan_indev 0
 69 #endif
 70 
 71 #define IS_IP(skb) \
 72         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IP))
 73 
 74 #define IS_IPV6(skb) \
 75         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_IPV6))
 76 
 77 #define IS_ARP(skb) \
 78         (!skb_vlan_tag_present(skb) && skb->protocol == htons(ETH_P_ARP))
 79 
 80 static inline __be16 vlan_proto(const struct sk_buff *skb)
 81 {
 82         if (skb_vlan_tag_present(skb))
 83                 return skb->protocol;
 84         else if (skb->protocol == htons(ETH_P_8021Q))
 85                 return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
 86         else
 87                 return 0;
 88 }
 89 
 90 #define IS_VLAN_IP(skb) \
 91         (vlan_proto(skb) == htons(ETH_P_IP) && \
 92          brnf_filter_vlan_tagged)
 93 
 94 #define IS_VLAN_IPV6(skb) \
 95         (vlan_proto(skb) == htons(ETH_P_IPV6) && \
 96          brnf_filter_vlan_tagged)
 97 
 98 #define IS_VLAN_ARP(skb) \
 99         (vlan_proto(skb) == htons(ETH_P_ARP) && \
100          brnf_filter_vlan_tagged)
101 
102 static inline __be16 pppoe_proto(const struct sk_buff *skb)
103 {
104         return *((__be16 *)(skb_mac_header(skb) + ETH_HLEN +
105                             sizeof(struct pppoe_hdr)));
106 }
107 
108 #define IS_PPPOE_IP(skb) \
109         (skb->protocol == htons(ETH_P_PPP_SES) && \
110          pppoe_proto(skb) == htons(PPP_IP) && \
111          brnf_filter_pppoe_tagged)
112 
113 #define IS_PPPOE_IPV6(skb) \
114         (skb->protocol == htons(ETH_P_PPP_SES) && \
115          pppoe_proto(skb) == htons(PPP_IPV6) && \
116          brnf_filter_pppoe_tagged)
117 
118 /* largest possible L2 header, see br_nf_dev_queue_xmit() */
119 #define NF_BRIDGE_MAX_MAC_HEADER_LENGTH (PPPOE_SES_HLEN + ETH_HLEN)
120 
121 struct brnf_frag_data {
122         char mac[NF_BRIDGE_MAX_MAC_HEADER_LENGTH];
123         u8 encap_size;
124         u8 size;
125         u16 vlan_tci;
126         __be16 vlan_proto;
127 };
128 
129 static DEFINE_PER_CPU(struct brnf_frag_data, brnf_frag_data_storage);
130 
131 static void nf_bridge_info_free(struct sk_buff *skb)
132 {
133         if (skb->nf_bridge) {
134                 nf_bridge_put(skb->nf_bridge);
135                 skb->nf_bridge = NULL;
136         }
137 }
138 
139 static inline struct net_device *bridge_parent(const struct net_device *dev)
140 {
141         struct net_bridge_port *port;
142 
143         port = br_port_get_rcu(dev);
144         return port ? port->br->dev : NULL;
145 }
146 
147 static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
148 {
149         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
150 
151         if (atomic_read(&nf_bridge->use) > 1) {
152                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
153 
154                 if (tmp) {
155                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
156                         atomic_set(&tmp->use, 1);
157                 }
158                 nf_bridge_put(nf_bridge);
159                 nf_bridge = tmp;
160         }
161         return nf_bridge;
162 }
163 
164 unsigned int nf_bridge_encap_header_len(const struct sk_buff *skb)
165 {
166         switch (skb->protocol) {
167         case __cpu_to_be16(ETH_P_8021Q):
168                 return VLAN_HLEN;
169         case __cpu_to_be16(ETH_P_PPP_SES):
170                 return PPPOE_SES_HLEN;
171         default:
172                 return 0;
173         }
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 /* When handing a packet over to the IP layer
193  * check whether we have a skb that is in the
194  * expected format
195  */
196 
197 static int br_validate_ipv4(struct net *net, struct sk_buff *skb)
198 {
199         const struct iphdr *iph;
200         u32 len;
201 
202         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
203                 goto inhdr_error;
204 
205         iph = ip_hdr(skb);
206 
207         /* Basic sanity checks */
208         if (iph->ihl < 5 || iph->version != 4)
209                 goto inhdr_error;
210 
211         if (!pskb_may_pull(skb, iph->ihl*4))
212                 goto inhdr_error;
213 
214         iph = ip_hdr(skb);
215         if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
216                 goto inhdr_error;
217 
218         len = ntohs(iph->tot_len);
219         if (skb->len < len) {
220                 IP_INC_STATS_BH(net, IPSTATS_MIB_INTRUNCATEDPKTS);
221                 goto drop;
222         } else if (len < (iph->ihl*4))
223                 goto inhdr_error;
224 
225         if (pskb_trim_rcsum(skb, len)) {
226                 IP_INC_STATS_BH(net, IPSTATS_MIB_INDISCARDS);
227                 goto drop;
228         }
229 
230         memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
231         /* We should really parse IP options here but until
232          * somebody who actually uses IP options complains to
233          * us we'll just silently ignore the options because
234          * we're lazy!
235          */
236         return 0;
237 
238 inhdr_error:
239         IP_INC_STATS_BH(net, IPSTATS_MIB_INHDRERRORS);
240 drop:
241         return -1;
242 }
243 
244 void nf_bridge_update_protocol(struct sk_buff *skb)
245 {
246         switch (skb->nf_bridge->orig_proto) {
247         case BRNF_PROTO_8021Q:
248                 skb->protocol = htons(ETH_P_8021Q);
249                 break;
250         case BRNF_PROTO_PPPOE:
251                 skb->protocol = htons(ETH_P_PPP_SES);
252                 break;
253         case BRNF_PROTO_UNCHANGED:
254                 break;
255         }
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 int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_buff *skb)
264 {
265         struct neighbour *neigh;
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         neigh = dst_neigh_lookup_skb(dst, skb);
273         if (neigh) {
274                 struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
275                 int ret;
276 
277                 if (neigh->hh.hh_len) {
278                         neigh_hh_bridge(&neigh->hh, skb);
279                         skb->dev = nf_bridge->physindev;
280                         ret = br_handle_frame_finish(net, sk, skb);
281                 } else {
282                         /* the neighbour function below overwrites the complete
283                          * MAC header, so we save the Ethernet source address and
284                          * protocol number.
285                          */
286                         skb_copy_from_linear_data_offset(skb,
287                                                          -(ETH_HLEN-ETH_ALEN),
288                                                          nf_bridge->neigh_header,
289                                                          ETH_HLEN-ETH_ALEN);
290                         /* tell br_dev_xmit to continue with forwarding */
291                         nf_bridge->bridged_dnat = 1;
292                         /* FIXME Need to refragment */
293                         ret = neigh->output(neigh, skb);
294                 }
295                 neigh_release(neigh);
296                 return ret;
297         }
298 free_skb:
299         kfree_skb(skb);
300         return 0;
301 }
302 
303 static inline bool
304 br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
305                              const struct nf_bridge_info *nf_bridge)
306 {
307         return ip_hdr(skb)->daddr != nf_bridge->ipv4_daddr;
308 }
309 
310 /* This requires some explaining. If DNAT has taken place,
311  * we will need to fix up the destination Ethernet address.
312  * This is also true when SNAT takes place (for the reply direction).
313  *
314  * There are two cases to consider:
315  * 1. The packet was DNAT'ed to a device in the same bridge
316  *    port group as it was received on. We can still bridge
317  *    the packet.
318  * 2. The packet was DNAT'ed to a different device, either
319  *    a non-bridged device or another bridge port group.
320  *    The packet will need to be routed.
321  *
322  * The correct way of distinguishing between these two cases is to
323  * call ip_route_input() and to look at skb->dst->dev, which is
324  * changed to the destination device if ip_route_input() succeeds.
325  *
326  * Let's first consider the case that ip_route_input() succeeds:
327  *
328  * If the output device equals the logical bridge device the packet
329  * came in on, we can consider this bridging. The corresponding MAC
330  * address will be obtained in br_nf_pre_routing_finish_bridge.
331  * Otherwise, the packet is considered to be routed and we just
332  * change the destination MAC address so that the packet will
333  * later be passed up to the IP stack to be routed. For a redirected
334  * packet, ip_route_input() will give back the localhost as output device,
335  * which differs from the bridge device.
336  *
337  * Let's now consider the case that ip_route_input() fails:
338  *
339  * This can be because the destination address is martian, in which case
340  * the packet will be dropped.
341  * If IP forwarding is disabled, ip_route_input() will fail, while
342  * ip_route_output_key() can return success. The source
343  * address for ip_route_output_key() is set to zero, so ip_route_output_key()
344  * thinks we're handling a locally generated packet and won't care
345  * if IP forwarding is enabled. If the output device equals the logical bridge
346  * device, we proceed as if ip_route_input() succeeded. If it differs from the
347  * logical bridge port or if ip_route_output_key() fails we drop the packet.
348  */
349 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
350 {
351         struct net_device *dev = skb->dev;
352         struct iphdr *iph = ip_hdr(skb);
353         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
354         struct rtable *rt;
355         int err;
356 
357         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
358 
359         if (nf_bridge->pkt_otherhost) {
360                 skb->pkt_type = PACKET_OTHERHOST;
361                 nf_bridge->pkt_otherhost = false;
362         }
363         nf_bridge->in_prerouting = 0;
364         if (br_nf_ipv4_daddr_was_changed(skb, nf_bridge)) {
365                 if ((err = ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev))) {
366                         struct in_device *in_dev = __in_dev_get_rcu(dev);
367 
368                         /* If err equals -EHOSTUNREACH the error is due to a
369                          * martian destination or due to the fact that
370                          * forwarding is disabled. For most martian packets,
371                          * ip_route_output_key() will fail. It won't fail for 2 types of
372                          * martian destinations: loopback destinations and destination
373                          * 0.0.0.0. In both cases the packet will be dropped because the
374                          * destination is the loopback device and not the bridge. */
375                         if (err != -EHOSTUNREACH || !in_dev || IN_DEV_FORWARD(in_dev))
376                                 goto free_skb;
377 
378                         rt = ip_route_output(net, iph->daddr, 0,
379                                              RT_TOS(iph->tos), 0);
380                         if (!IS_ERR(rt)) {
381                                 /* - Bridged-and-DNAT'ed traffic doesn't
382                                  *   require ip_forwarding. */
383                                 if (rt->dst.dev == dev) {
384                                         skb_dst_set(skb, &rt->dst);
385                                         goto bridged_dnat;
386                                 }
387                                 ip_rt_put(rt);
388                         }
389 free_skb:
390                         kfree_skb(skb);
391                         return 0;
392                 } else {
393                         if (skb_dst(skb)->dev == dev) {
394 bridged_dnat:
395                                 skb->dev = nf_bridge->physindev;
396                                 nf_bridge_update_protocol(skb);
397                                 nf_bridge_push_encap_header(skb);
398                                 NF_HOOK_THRESH(NFPROTO_BRIDGE,
399                                                NF_BR_PRE_ROUTING,
400                                                net, sk, skb, skb->dev, NULL,
401                                                br_nf_pre_routing_finish_bridge,
402                                                1);
403                                 return 0;
404                         }
405                         ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
406                         skb->pkt_type = PACKET_HOST;
407                 }
408         } else {
409                 rt = bridge_parent_rtable(nf_bridge->physindev);
410                 if (!rt) {
411                         kfree_skb(skb);
412                         return 0;
413                 }
414                 skb_dst_set_noref(skb, &rt->dst);
415         }
416 
417         skb->dev = nf_bridge->physindev;
418         nf_bridge_update_protocol(skb);
419         nf_bridge_push_encap_header(skb);
420         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, net, sk, skb,
421                        skb->dev, NULL,
422                        br_handle_frame_finish, 1);
423 
424         return 0;
425 }
426 
427 static struct net_device *brnf_get_logical_dev(struct sk_buff *skb, const struct net_device *dev)
428 {
429         struct net_device *vlan, *br;
430 
431         br = bridge_parent(dev);
432         if (brnf_pass_vlan_indev == 0 || !skb_vlan_tag_present(skb))
433                 return br;
434 
435         vlan = __vlan_find_dev_deep_rcu(br, skb->vlan_proto,
436                                     skb_vlan_tag_get(skb) & VLAN_VID_MASK);
437 
438         return vlan ? vlan : br;
439 }
440 
441 /* Some common code for IPv4/IPv6 */
442 struct net_device *setup_pre_routing(struct sk_buff *skb)
443 {
444         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
445 
446         if (skb->pkt_type == PACKET_OTHERHOST) {
447                 skb->pkt_type = PACKET_HOST;
448                 nf_bridge->pkt_otherhost = true;
449         }
450 
451         nf_bridge->in_prerouting = 1;
452         nf_bridge->physindev = skb->dev;
453         skb->dev = brnf_get_logical_dev(skb, skb->dev);
454 
455         if (skb->protocol == htons(ETH_P_8021Q))
456                 nf_bridge->orig_proto = BRNF_PROTO_8021Q;
457         else if (skb->protocol == htons(ETH_P_PPP_SES))
458                 nf_bridge->orig_proto = BRNF_PROTO_PPPOE;
459 
460         /* Must drop socket now because of tproxy. */
461         skb_orphan(skb);
462         return skb->dev;
463 }
464 
465 /* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
466  * Replicate the checks that IPv4 does on packet reception.
467  * Set skb->dev to the bridge device (i.e. parent of the
468  * receiving device) to make netfilter happy, the REDIRECT
469  * target in particular.  Save the original destination IP
470  * address to be able to detect DNAT afterwards. */
471 static unsigned int br_nf_pre_routing(void *priv,
472                                       struct sk_buff *skb,
473                                       const struct nf_hook_state *state)
474 {
475         struct nf_bridge_info *nf_bridge;
476         struct net_bridge_port *p;
477         struct net_bridge *br;
478         __u32 len = nf_bridge_encap_header_len(skb);
479 
480         if (unlikely(!pskb_may_pull(skb, len)))
481                 return NF_DROP;
482 
483         p = br_port_get_rcu(state->in);
484         if (p == NULL)
485                 return NF_DROP;
486         br = p->br;
487 
488         if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb)) {
489                 if (!brnf_call_ip6tables && !br->nf_call_ip6tables)
490                         return NF_ACCEPT;
491 
492                 nf_bridge_pull_encap_header_rcsum(skb);
493                 return br_nf_pre_routing_ipv6(priv, skb, state);
494         }
495 
496         if (!brnf_call_iptables && !br->nf_call_iptables)
497                 return NF_ACCEPT;
498 
499         if (!IS_IP(skb) && !IS_VLAN_IP(skb) && !IS_PPPOE_IP(skb))
500                 return NF_ACCEPT;
501 
502         nf_bridge_pull_encap_header_rcsum(skb);
503 
504         if (br_validate_ipv4(state->net, skb))
505                 return NF_DROP;
506 
507         nf_bridge_put(skb->nf_bridge);
508         if (!nf_bridge_alloc(skb))
509                 return NF_DROP;
510         if (!setup_pre_routing(skb))
511                 return NF_DROP;
512 
513         nf_bridge = nf_bridge_info_get(skb);
514         nf_bridge->ipv4_daddr = ip_hdr(skb)->daddr;
515 
516         skb->protocol = htons(ETH_P_IP);
517 
518         NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, state->net, state->sk, skb,
519                 skb->dev, NULL,
520                 br_nf_pre_routing_finish);
521 
522         return NF_STOLEN;
523 }
524 
525 
526 /* PF_BRIDGE/LOCAL_IN ************************************************/
527 /* The packet is locally destined, which requires a real
528  * dst_entry, so detach the fake one.  On the way up, the
529  * packet would pass through PRE_ROUTING again (which already
530  * took place when the packet entered the bridge), but we
531  * register an IPv4 PRE_ROUTING 'sabotage' hook that will
532  * prevent this from happening. */
533 static unsigned int br_nf_local_in(void *priv,
534                                    struct sk_buff *skb,
535                                    const struct nf_hook_state *state)
536 {
537         br_drop_fake_rtable(skb);
538         return NF_ACCEPT;
539 }
540 
541 /* PF_BRIDGE/FORWARD *************************************************/
542 static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
543 {
544         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
545         struct net_device *in;
546 
547         if (!IS_ARP(skb) && !IS_VLAN_ARP(skb)) {
548 
549                 if (skb->protocol == htons(ETH_P_IP))
550                         nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
551 
552                 if (skb->protocol == htons(ETH_P_IPV6))
553                         nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
554 
555                 in = nf_bridge->physindev;
556                 if (nf_bridge->pkt_otherhost) {
557                         skb->pkt_type = PACKET_OTHERHOST;
558                         nf_bridge->pkt_otherhost = false;
559                 }
560                 nf_bridge_update_protocol(skb);
561         } else {
562                 in = *((struct net_device **)(skb->cb));
563         }
564         nf_bridge_push_encap_header(skb);
565 
566         NF_HOOK_THRESH(NFPROTO_BRIDGE, NF_BR_FORWARD, net, sk, skb,
567                        in, skb->dev, br_forward_finish, 1);
568         return 0;
569 }
570 
571 
572 /* This is the 'purely bridged' case.  For IP, we pass the packet to
573  * netfilter with indev and outdev set to the bridge device,
574  * but we are still able to filter on the 'real' indev/outdev
575  * because of the physdev module. For ARP, indev and outdev are the
576  * bridge ports. */
577 static unsigned int br_nf_forward_ip(void *priv,
578                                      struct sk_buff *skb,
579                                      const struct nf_hook_state *state)
580 {
581         struct nf_bridge_info *nf_bridge;
582         struct net_device *parent;
583         u_int8_t pf;
584 
585         if (!skb->nf_bridge)
586                 return NF_ACCEPT;
587 
588         /* Need exclusive nf_bridge_info since we might have multiple
589          * different physoutdevs. */
590         if (!nf_bridge_unshare(skb))
591                 return NF_DROP;
592 
593         nf_bridge = nf_bridge_info_get(skb);
594         if (!nf_bridge)
595                 return NF_DROP;
596 
597         parent = bridge_parent(state->out);
598         if (!parent)
599                 return NF_DROP;
600 
601         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
602                 pf = NFPROTO_IPV4;
603         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
604                 pf = NFPROTO_IPV6;
605         else
606                 return NF_ACCEPT;
607 
608         nf_bridge_pull_encap_header(skb);
609 
610         if (skb->pkt_type == PACKET_OTHERHOST) {
611                 skb->pkt_type = PACKET_HOST;
612                 nf_bridge->pkt_otherhost = true;
613         }
614 
615         if (pf == NFPROTO_IPV4) {
616                 if (br_validate_ipv4(state->net, skb))
617                         return NF_DROP;
618                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
619         }
620 
621         if (pf == NFPROTO_IPV6) {
622                 if (br_validate_ipv6(state->net, skb))
623                         return NF_DROP;
624                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
625         }
626 
627         nf_bridge->physoutdev = skb->dev;
628         if (pf == NFPROTO_IPV4)
629                 skb->protocol = htons(ETH_P_IP);
630         else
631                 skb->protocol = htons(ETH_P_IPV6);
632 
633         NF_HOOK(pf, NF_INET_FORWARD, state->net, NULL, skb,
634                 brnf_get_logical_dev(skb, state->in),
635                 parent, br_nf_forward_finish);
636 
637         return NF_STOLEN;
638 }
639 
640 static unsigned int br_nf_forward_arp(void *priv,
641                                       struct sk_buff *skb,
642                                       const struct nf_hook_state *state)
643 {
644         struct net_bridge_port *p;
645         struct net_bridge *br;
646         struct net_device **d = (struct net_device **)(skb->cb);
647 
648         p = br_port_get_rcu(state->out);
649         if (p == NULL)
650                 return NF_ACCEPT;
651         br = p->br;
652 
653         if (!brnf_call_arptables && !br->nf_call_arptables)
654                 return NF_ACCEPT;
655 
656         if (!IS_ARP(skb)) {
657                 if (!IS_VLAN_ARP(skb))
658                         return NF_ACCEPT;
659                 nf_bridge_pull_encap_header(skb);
660         }
661 
662         if (arp_hdr(skb)->ar_pln != 4) {
663                 if (IS_VLAN_ARP(skb))
664                         nf_bridge_push_encap_header(skb);
665                 return NF_ACCEPT;
666         }
667         *d = state->in;
668         NF_HOOK(NFPROTO_ARP, NF_ARP_FORWARD, state->net, state->sk, skb,
669                 state->in, state->out, br_nf_forward_finish);
670 
671         return NF_STOLEN;
672 }
673 
674 static int br_nf_push_frag_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
675 {
676         struct brnf_frag_data *data;
677         int err;
678 
679         data = this_cpu_ptr(&brnf_frag_data_storage);
680         err = skb_cow_head(skb, data->size);
681 
682         if (err) {
683                 kfree_skb(skb);
684                 return 0;
685         }
686 
687         if (data->vlan_tci) {
688                 skb->vlan_tci = data->vlan_tci;
689                 skb->vlan_proto = data->vlan_proto;
690         }
691 
692         skb_copy_to_linear_data_offset(skb, -data->size, data->mac, data->size);
693         __skb_push(skb, data->encap_size);
694 
695         nf_bridge_info_free(skb);
696         return br_dev_queue_push_xmit(net, sk, skb);
697 }
698 
699 static int
700 br_nf_ip_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
701                   int (*output)(struct net *, struct sock *, struct sk_buff *))
702 {
703         unsigned int mtu = ip_skb_dst_mtu(skb);
704         struct iphdr *iph = ip_hdr(skb);
705 
706         if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->ignore_df) ||
707                      (IPCB(skb)->frag_max_size &&
708                       IPCB(skb)->frag_max_size > mtu))) {
709                 IP_INC_STATS(net, IPSTATS_MIB_FRAGFAILS);
710                 kfree_skb(skb);
711                 return -EMSGSIZE;
712         }
713 
714         return ip_do_fragment(net, sk, skb, output);
715 }
716 
717 static unsigned int nf_bridge_mtu_reduction(const struct sk_buff *skb)
718 {
719         if (skb->nf_bridge->orig_proto == BRNF_PROTO_PPPOE)
720                 return PPPOE_SES_HLEN;
721         return 0;
722 }
723 
724 static int br_nf_dev_queue_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
725 {
726         struct nf_bridge_info *nf_bridge;
727         unsigned int mtu_reserved;
728 
729         mtu_reserved = nf_bridge_mtu_reduction(skb);
730 
731         if (skb_is_gso(skb) || skb->len + mtu_reserved <= skb->dev->mtu) {
732                 nf_bridge_info_free(skb);
733                 return br_dev_queue_push_xmit(net, sk, skb);
734         }
735 
736         nf_bridge = nf_bridge_info_get(skb);
737 
738         /* This is wrong! We should preserve the original fragment
739          * boundaries by preserving frag_list rather than refragmenting.
740          */
741         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV4) &&
742             skb->protocol == htons(ETH_P_IP)) {
743                 struct brnf_frag_data *data;
744 
745                 if (br_validate_ipv4(net, skb))
746                         goto drop;
747 
748                 IPCB(skb)->frag_max_size = nf_bridge->frag_max_size;
749 
750                 nf_bridge_update_protocol(skb);
751 
752                 data = this_cpu_ptr(&brnf_frag_data_storage);
753 
754                 data->vlan_tci = skb->vlan_tci;
755                 data->vlan_proto = skb->vlan_proto;
756                 data->encap_size = nf_bridge_encap_header_len(skb);
757                 data->size = ETH_HLEN + data->encap_size;
758 
759                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
760                                                  data->size);
761 
762                 return br_nf_ip_fragment(net, sk, skb, br_nf_push_frag_xmit);
763         }
764         if (IS_ENABLED(CONFIG_NF_DEFRAG_IPV6) &&
765             skb->protocol == htons(ETH_P_IPV6)) {
766                 const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
767                 struct brnf_frag_data *data;
768 
769                 if (br_validate_ipv6(net, skb))
770                         goto drop;
771 
772                 IP6CB(skb)->frag_max_size = nf_bridge->frag_max_size;
773 
774                 nf_bridge_update_protocol(skb);
775 
776                 data = this_cpu_ptr(&brnf_frag_data_storage);
777                 data->encap_size = nf_bridge_encap_header_len(skb);
778                 data->size = ETH_HLEN + data->encap_size;
779 
780                 skb_copy_from_linear_data_offset(skb, -data->size, data->mac,
781                                                  data->size);
782 
783                 if (v6ops)
784                         return v6ops->fragment(net, sk, skb, br_nf_push_frag_xmit);
785 
786                 kfree_skb(skb);
787                 return -EMSGSIZE;
788         }
789         nf_bridge_info_free(skb);
790         return br_dev_queue_push_xmit(net, sk, skb);
791  drop:
792         kfree_skb(skb);
793         return 0;
794 }
795 
796 /* PF_BRIDGE/POST_ROUTING ********************************************/
797 static unsigned int br_nf_post_routing(void *priv,
798                                        struct sk_buff *skb,
799                                        const struct nf_hook_state *state)
800 {
801         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
802         struct net_device *realoutdev = bridge_parent(skb->dev);
803         u_int8_t pf;
804 
805         /* if nf_bridge is set, but ->physoutdev is NULL, this packet came in
806          * on a bridge, but was delivered locally and is now being routed:
807          *
808          * POST_ROUTING was already invoked from the ip stack.
809          */
810         if (!nf_bridge || !nf_bridge->physoutdev)
811                 return NF_ACCEPT;
812 
813         if (!realoutdev)
814                 return NF_DROP;
815 
816         if (IS_IP(skb) || IS_VLAN_IP(skb) || IS_PPPOE_IP(skb))
817                 pf = NFPROTO_IPV4;
818         else if (IS_IPV6(skb) || IS_VLAN_IPV6(skb) || IS_PPPOE_IPV6(skb))
819                 pf = NFPROTO_IPV6;
820         else
821                 return NF_ACCEPT;
822 
823         /* We assume any code from br_dev_queue_push_xmit onwards doesn't care
824          * about the value of skb->pkt_type. */
825         if (skb->pkt_type == PACKET_OTHERHOST) {
826                 skb->pkt_type = PACKET_HOST;
827                 nf_bridge->pkt_otherhost = true;
828         }
829 
830         nf_bridge_pull_encap_header(skb);
831         if (pf == NFPROTO_IPV4)
832                 skb->protocol = htons(ETH_P_IP);
833         else
834                 skb->protocol = htons(ETH_P_IPV6);
835 
836         NF_HOOK(pf, NF_INET_POST_ROUTING, state->net, state->sk, skb,
837                 NULL, realoutdev,
838                 br_nf_dev_queue_xmit);
839 
840         return NF_STOLEN;
841 }
842 
843 /* IP/SABOTAGE *****************************************************/
844 /* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
845  * for the second time. */
846 static unsigned int ip_sabotage_in(void *priv,
847                                    struct sk_buff *skb,
848                                    const struct nf_hook_state *state)
849 {
850         if (skb->nf_bridge && !skb->nf_bridge->in_prerouting)
851                 return NF_STOP;
852 
853         return NF_ACCEPT;
854 }
855 
856 /* This is called when br_netfilter has called into iptables/netfilter,
857  * and DNAT has taken place on a bridge-forwarded packet.
858  *
859  * neigh->output has created a new MAC header, with local br0 MAC
860  * as saddr.
861  *
862  * This restores the original MAC saddr of the bridged packet
863  * before invoking bridge forward logic to transmit the packet.
864  */
865 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
866 {
867         struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
868 
869         skb_pull(skb, ETH_HLEN);
870         nf_bridge->bridged_dnat = 0;
871 
872         BUILD_BUG_ON(sizeof(nf_bridge->neigh_header) != (ETH_HLEN - ETH_ALEN));
873 
874         skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
875                                        nf_bridge->neigh_header,
876                                        ETH_HLEN - ETH_ALEN);
877         skb->dev = nf_bridge->physindev;
878 
879         nf_bridge->physoutdev = NULL;
880         br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
881 }
882 
883 static int br_nf_dev_xmit(struct sk_buff *skb)
884 {
885         if (skb->nf_bridge && skb->nf_bridge->bridged_dnat) {
886                 br_nf_pre_routing_finish_bridge_slow(skb);
887                 return 1;
888         }
889         return 0;
890 }
891 
892 static const struct nf_br_ops br_ops = {
893         .br_dev_xmit_hook =     br_nf_dev_xmit,
894 };
895 
896 void br_netfilter_enable(void)
897 {
898 }
899 EXPORT_SYMBOL_GPL(br_netfilter_enable);
900 
901 /* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
902  * br_dev_queue_push_xmit is called afterwards */
903 static struct nf_hook_ops br_nf_ops[] __read_mostly = {
904         {
905                 .hook = br_nf_pre_routing,
906                 .pf = NFPROTO_BRIDGE,
907                 .hooknum = NF_BR_PRE_ROUTING,
908                 .priority = NF_BR_PRI_BRNF,
909         },
910         {
911                 .hook = br_nf_local_in,
912                 .pf = NFPROTO_BRIDGE,
913                 .hooknum = NF_BR_LOCAL_IN,
914                 .priority = NF_BR_PRI_BRNF,
915         },
916         {
917                 .hook = br_nf_forward_ip,
918                 .pf = NFPROTO_BRIDGE,
919                 .hooknum = NF_BR_FORWARD,
920                 .priority = NF_BR_PRI_BRNF - 1,
921         },
922         {
923                 .hook = br_nf_forward_arp,
924                 .pf = NFPROTO_BRIDGE,
925                 .hooknum = NF_BR_FORWARD,
926                 .priority = NF_BR_PRI_BRNF,
927         },
928         {
929                 .hook = br_nf_post_routing,
930                 .pf = NFPROTO_BRIDGE,
931                 .hooknum = NF_BR_POST_ROUTING,
932                 .priority = NF_BR_PRI_LAST,
933         },
934         {
935                 .hook = ip_sabotage_in,
936                 .pf = NFPROTO_IPV4,
937                 .hooknum = NF_INET_PRE_ROUTING,
938                 .priority = NF_IP_PRI_FIRST,
939         },
940         {
941                 .hook = ip_sabotage_in,
942                 .pf = NFPROTO_IPV6,
943                 .hooknum = NF_INET_PRE_ROUTING,
944                 .priority = NF_IP6_PRI_FIRST,
945         },
946 };
947 
948 static int brnf_device_event(struct notifier_block *unused, unsigned long event,
949                              void *ptr)
950 {
951         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
952         struct brnf_net *brnet;
953         struct net *net;
954         int ret;
955 
956         if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
957                 return NOTIFY_DONE;
958 
959         ASSERT_RTNL();
960 
961         net = dev_net(dev);
962         brnet = net_generic(net, brnf_net_id);
963         if (brnet->enabled)
964                 return NOTIFY_OK;
965 
966         ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
967         if (ret)
968                 return NOTIFY_BAD;
969 
970         brnet->enabled = true;
971         return NOTIFY_OK;
972 }
973 
974 static void __net_exit brnf_exit_net(struct net *net)
975 {
976         struct brnf_net *brnet = net_generic(net, brnf_net_id);
977 
978         if (!brnet->enabled)
979                 return;
980 
981         nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
982         brnet->enabled = false;
983 }
984 
985 static struct pernet_operations brnf_net_ops __read_mostly = {
986         .exit = brnf_exit_net,
987         .id   = &brnf_net_id,
988         .size = sizeof(struct brnf_net),
989 };
990 
991 static struct notifier_block brnf_notifier __read_mostly = {
992         .notifier_call = brnf_device_event,
993 };
994 
995 #ifdef CONFIG_SYSCTL
996 static
997 int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
998                             void __user *buffer, size_t *lenp, loff_t *ppos)
999 {
1000         int ret;
1001 
1002         ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
1003 
1004         if (write && *(int *)(ctl->data))
1005                 *(int *)(ctl->data) = 1;
1006         return ret;
1007 }
1008 
1009 static struct ctl_table brnf_table[] = {
1010         {
1011                 .procname       = "bridge-nf-call-arptables",
1012                 .data           = &brnf_call_arptables,
1013                 .maxlen         = sizeof(int),
1014                 .mode           = 0644,
1015                 .proc_handler   = brnf_sysctl_call_tables,
1016         },
1017         {
1018                 .procname       = "bridge-nf-call-iptables",
1019                 .data           = &brnf_call_iptables,
1020                 .maxlen         = sizeof(int),
1021                 .mode           = 0644,
1022                 .proc_handler   = brnf_sysctl_call_tables,
1023         },
1024         {
1025                 .procname       = "bridge-nf-call-ip6tables",
1026                 .data           = &brnf_call_ip6tables,
1027                 .maxlen         = sizeof(int),
1028                 .mode           = 0644,
1029                 .proc_handler   = brnf_sysctl_call_tables,
1030         },
1031         {
1032                 .procname       = "bridge-nf-filter-vlan-tagged",
1033                 .data           = &brnf_filter_vlan_tagged,
1034                 .maxlen         = sizeof(int),
1035                 .mode           = 0644,
1036                 .proc_handler   = brnf_sysctl_call_tables,
1037         },
1038         {
1039                 .procname       = "bridge-nf-filter-pppoe-tagged",
1040                 .data           = &brnf_filter_pppoe_tagged,
1041                 .maxlen         = sizeof(int),
1042                 .mode           = 0644,
1043                 .proc_handler   = brnf_sysctl_call_tables,
1044         },
1045         {
1046                 .procname       = "bridge-nf-pass-vlan-input-dev",
1047                 .data           = &brnf_pass_vlan_indev,
1048                 .maxlen         = sizeof(int),
1049                 .mode           = 0644,
1050                 .proc_handler   = brnf_sysctl_call_tables,
1051         },
1052         { }
1053 };
1054 #endif
1055 
1056 static int __init br_netfilter_init(void)
1057 {
1058         int ret;
1059 
1060         ret = register_pernet_subsys(&brnf_net_ops);
1061         if (ret < 0)
1062                 return ret;
1063 
1064         ret = register_netdevice_notifier(&brnf_notifier);
1065         if (ret < 0) {
1066                 unregister_pernet_subsys(&brnf_net_ops);
1067                 return ret;
1068         }
1069 
1070 #ifdef CONFIG_SYSCTL
1071         brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
1072         if (brnf_sysctl_header == NULL) {
1073                 printk(KERN_WARNING
1074                        "br_netfilter: can't register to sysctl.\n");
1075                 unregister_netdevice_notifier(&brnf_notifier);
1076                 unregister_pernet_subsys(&brnf_net_ops);
1077                 return -ENOMEM;
1078         }
1079 #endif
1080         RCU_INIT_POINTER(nf_br_ops, &br_ops);
1081         printk(KERN_NOTICE "Bridge firewalling registered\n");
1082         return 0;
1083 }
1084 
1085 static void __exit br_netfilter_fini(void)
1086 {
1087         RCU_INIT_POINTER(nf_br_ops, NULL);
1088         unregister_netdevice_notifier(&brnf_notifier);
1089         unregister_pernet_subsys(&brnf_net_ops);
1090 #ifdef CONFIG_SYSCTL
1091         unregister_net_sysctl_table(brnf_sysctl_header);
1092 #endif
1093 }
1094 
1095 module_init(br_netfilter_init);
1096 module_exit(br_netfilter_fini);
1097 
1098 MODULE_LICENSE("GPL");
1099 MODULE_AUTHOR("Lennert Buytenhek <buytenh@gnu.org>");
1100 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
1101 MODULE_DESCRIPTION("Linux ethernet netfilter firewall bridge");
1102 

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