forked from torvalds/linux
-
Notifications
You must be signed in to change notification settings - Fork 1
/
Copy pathbr_netfilter.c
1111 lines (967 loc) · 30.1 KB
/
br_netfilter.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Handle firewalling
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <[email protected]>
* Bart De Schuymer (maintainer) <[email protected]>
*
* Changes:
* Apr 29 2003: physdev module support (bdschuym)
* Jun 19 2003: let arptables see bridged ARP traffic (bdschuym)
* Oct 06 2003: filter encapsulated IP/ARP VLAN traffic on untagged bridge
* (bdschuym)
* Sep 01 2004: add IPv6 filtering (bdschuym)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Lennert dedicates this file to Kerstin Wurdinger.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/ip.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv4.h>
#include <linux/netfilter_ipv6.h>
#include <linux/netfilter_arp.h>
#include <linux/in_route.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/route.h>
#include <asm/uaccess.h>
#include <asm/checksum.h>
#include "br_private.h"
#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif
#define skb_origaddr(skb) (((struct bridge_skb_cb *) \
(skb->nf_bridge->data))->daddr.ipv4)
#define store_orig_dstaddr(skb) (skb_origaddr(skb) = (skb)->nh.iph->daddr)
#define dnat_took_place(skb) (skb_origaddr(skb) != (skb)->nh.iph->daddr)
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *brnf_sysctl_header;
static int brnf_call_iptables = 1;
static int brnf_call_ip6tables = 1;
static int brnf_call_arptables = 1;
static int brnf_filter_vlan_tagged = 1;
#else
#define brnf_filter_vlan_tagged 1
#endif
static __be16 inline vlan_proto(const struct sk_buff *skb)
{
return vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
}
#define IS_VLAN_IP(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_IP) && \
brnf_filter_vlan_tagged)
#define IS_VLAN_IPV6(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_IPV6) &&\
brnf_filter_vlan_tagged)
#define IS_VLAN_ARP(skb) \
(skb->protocol == htons(ETH_P_8021Q) && \
vlan_proto(skb) == htons(ETH_P_ARP) && \
brnf_filter_vlan_tagged)
/* We need these fake structures to make netfilter happy --
* lots of places assume that skb->dst != NULL, which isn't
* all that unreasonable.
*
* Currently, we fill in the PMTU entry because netfilter
* refragmentation needs it, and the rt_flags entry because
* ipt_REJECT needs it. Future netfilter modules might
* require us to fill additional fields. */
static struct net_device __fake_net_device = {
.hard_header_len = ETH_HLEN
};
static struct rtable __fake_rtable = {
.u = {
.dst = {
.__refcnt = ATOMIC_INIT(1),
.dev = &__fake_net_device,
.path = &__fake_rtable.u.dst,
.metrics = {[RTAX_MTU - 1] = 1500},
.flags = DST_NOXFRM,
}
},
.rt_flags = 0,
};
static inline struct net_device *bridge_parent(const struct net_device *dev)
{
struct net_bridge_port *port = rcu_dereference(dev->br_port);
return port ? port->br->dev : NULL;
}
static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
{
skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
if (likely(skb->nf_bridge))
atomic_set(&(skb->nf_bridge->use), 1);
return skb->nf_bridge;
}
static inline void nf_bridge_save_header(struct sk_buff *skb)
{
int header_size = 16;
if (skb->protocol == htons(ETH_P_8021Q))
header_size = 18;
memcpy(skb->nf_bridge->data, skb->data - header_size, header_size);
}
/* PF_BRIDGE/PRE_ROUTING *********************************************/
/* Undo the changes made for ip6tables PREROUTING and continue the
* bridge PRE_ROUTING hook. */
static int br_nf_pre_routing_finish_ipv6(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
skb->dst = (struct dst_entry *)&__fake_rtable;
dst_hold(skb->dst);
skb->dev = nf_bridge->physindev;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish, 1);
return 0;
}
static void __br_dnat_complain(void)
{
static unsigned long last_complaint;
if (jiffies - last_complaint >= 5 * HZ) {
printk(KERN_WARNING "Performing cross-bridge DNAT requires IP "
"forwarding to be enabled\n");
last_complaint = jiffies;
}
}
/* This requires some explaining. If DNAT has taken place,
* we will need to fix up the destination Ethernet address,
* and this is a tricky process.
*
* There are two cases to consider:
* 1. The packet was DNAT'ed to a device in the same bridge
* port group as it was received on. We can still bridge
* the packet.
* 2. The packet was DNAT'ed to a different device, either
* a non-bridged device or another bridge port group.
* The packet will need to be routed.
*
* The correct way of distinguishing between these two cases is to
* call ip_route_input() and to look at skb->dst->dev, which is
* changed to the destination device if ip_route_input() succeeds.
*
* Let us first consider the case that ip_route_input() succeeds:
*
* If skb->dst->dev equals the logical bridge device the packet
* came in on, we can consider this bridging. We then call
* skb->dst->output() which will make the packet enter br_nf_local_out()
* not much later. In that function it is assured that the iptables
* FORWARD chain is traversed for the packet.
*
* Otherwise, the packet is considered to be routed and we just
* change the destination MAC address so that the packet will
* later be passed up to the IP stack to be routed.
*
* Let us now consider the case that ip_route_input() fails:
*
* After a "echo '0' > /proc/sys/net/ipv4/ip_forward" ip_route_input()
* will fail, while __ip_route_output_key() will return success. The source
* address for __ip_route_output_key() is set to zero, so __ip_route_output_key
* thinks we're handling a locally generated packet and won't care
* if IP forwarding is allowed. We send a warning message to the users's
* log telling her to put IP forwarding on.
*
* ip_route_input() will also fail if there is no route available.
* In that case we just drop the packet.
*
* --Lennert, 20020411
* --Bart, 20020416 (updated)
* --Bart, 20021007 (updated) */
static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
{
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
skb->nf_bridge->mask |= BRNF_PKT_TYPE;
}
skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
skb->dev = bridge_parent(skb->dev);
if (!skb->dev)
kfree_skb(skb);
else {
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
skb->dst->output(skb);
}
return 0;
}
static int br_nf_pre_routing_finish(struct sk_buff *skb)
{
struct net_device *dev = skb->dev;
struct iphdr *iph = skb->nh.iph;
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
if (dnat_took_place(skb)) {
if (ip_route_input(skb, iph->daddr, iph->saddr, iph->tos, dev)) {
struct rtable *rt;
struct flowi fl = {
.nl_u = {
.ip4_u = {
.daddr = iph->daddr,
.saddr = 0,
.tos = RT_TOS(iph->tos) },
},
.proto = 0,
};
if (!ip_route_output_key(&rt, &fl)) {
/* - Bridged-and-DNAT'ed traffic doesn't
* require ip_forwarding.
* - Deal with redirected traffic. */
if (((struct dst_entry *)rt)->dev == dev ||
rt->rt_type == RTN_LOCAL) {
skb->dst = (struct dst_entry *)rt;
goto bridged_dnat;
}
__br_dnat_complain();
dst_release((struct dst_entry *)rt);
}
kfree_skb(skb);
return 0;
} else {
if (skb->dst->dev == dev) {
bridged_dnat:
/* Tell br_nf_local_out this is a
* bridged frame */
nf_bridge->mask |= BRNF_BRIDGED_DNAT;
skb->dev = nf_bridge->physindev;
if (skb->protocol ==
htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING,
skb, skb->dev, NULL,
br_nf_pre_routing_finish_bridge,
1);
return 0;
}
memcpy(eth_hdr(skb)->h_dest, dev->dev_addr, ETH_ALEN);
skb->pkt_type = PACKET_HOST;
}
} else {
skb->dst = (struct dst_entry *)&__fake_rtable;
dst_hold(skb->dst);
}
skb->dev = nf_bridge->physindev;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish, 1);
return 0;
}
/* Some common code for IPv4/IPv6 */
static struct net_device *setup_pre_routing(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
nf_bridge->physindev = skb->dev;
skb->dev = bridge_parent(skb->dev);
return skb->dev;
}
/* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
static int check_hbh_len(struct sk_buff *skb)
{
unsigned char *raw = (u8 *) (skb->nh.ipv6h + 1);
u32 pkt_len;
int off = raw - skb->nh.raw;
int len = (raw[1] + 1) << 3;
if ((raw + len) - skb->data > skb_headlen(skb))
goto bad;
off += 2;
len -= 2;
while (len > 0) {
int optlen = skb->nh.raw[off + 1] + 2;
switch (skb->nh.raw[off]) {
case IPV6_TLV_PAD0:
optlen = 1;
break;
case IPV6_TLV_PADN:
break;
case IPV6_TLV_JUMBO:
if (skb->nh.raw[off + 1] != 4 || (off & 3) != 2)
goto bad;
pkt_len = ntohl(*(u32 *) (skb->nh.raw + off + 2));
if (pkt_len <= IPV6_MAXPLEN ||
skb->nh.ipv6h->payload_len)
goto bad;
if (pkt_len > skb->len - sizeof(struct ipv6hdr))
goto bad;
if (pskb_trim_rcsum(skb,
pkt_len + sizeof(struct ipv6hdr)))
goto bad;
break;
default:
if (optlen > len)
goto bad;
break;
}
off += optlen;
len -= optlen;
}
if (len == 0)
return 0;
bad:
return -1;
}
/* Replicate the checks that IPv6 does on packet reception and pass the packet
* to ip6tables, which doesn't support NAT, so things are fairly simple. */
static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct ipv6hdr *hdr;
u32 pkt_len;
if (skb->len < sizeof(struct ipv6hdr))
goto inhdr_error;
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto inhdr_error;
hdr = skb->nh.ipv6h;
if (hdr->version != 6)
goto inhdr_error;
pkt_len = ntohs(hdr->payload_len);
if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
if (pkt_len + sizeof(struct ipv6hdr) > skb->len)
goto inhdr_error;
if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
goto inhdr_error;
}
if (hdr->nexthdr == NEXTHDR_HOP && check_hbh_len(skb))
goto inhdr_error;
nf_bridge_put(skb->nf_bridge);
if (!nf_bridge_alloc(skb))
return NF_DROP;
if (!setup_pre_routing(skb))
return NF_DROP;
NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
br_nf_pre_routing_finish_ipv6);
return NF_STOLEN;
inhdr_error:
return NF_DROP;
}
/* Direct IPv6 traffic to br_nf_pre_routing_ipv6.
* Replicate the checks that IPv4 does on packet reception.
* Set skb->dev to the bridge device (i.e. parent of the
* receiving device) to make netfilter happy, the REDIRECT
* target in particular. Save the original destination IP
* address to be able to detect DNAT afterwards. */
static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct iphdr *iph;
__u32 len;
struct sk_buff *skb = *pskb;
if (skb->protocol == htons(ETH_P_IPV6) || IS_VLAN_IPV6(skb)) {
#ifdef CONFIG_SYSCTL
if (!brnf_call_ip6tables)
return NF_ACCEPT;
#endif
if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
goto out;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
return br_nf_pre_routing_ipv6(hook, skb, in, out, okfn);
}
#ifdef CONFIG_SYSCTL
if (!brnf_call_iptables)
return NF_ACCEPT;
#endif
if (skb->protocol != htons(ETH_P_IP) && !IS_VLAN_IP(skb))
return NF_ACCEPT;
if ((skb = skb_share_check(*pskb, GFP_ATOMIC)) == NULL)
goto out;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull_rcsum(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
if (!pskb_may_pull(skb, sizeof(struct iphdr)))
goto inhdr_error;
iph = skb->nh.iph;
if (iph->ihl < 5 || iph->version != 4)
goto inhdr_error;
if (!pskb_may_pull(skb, 4 * iph->ihl))
goto inhdr_error;
iph = skb->nh.iph;
if (ip_fast_csum((__u8 *) iph, iph->ihl) != 0)
goto inhdr_error;
len = ntohs(iph->tot_len);
if (skb->len < len || len < 4 * iph->ihl)
goto inhdr_error;
pskb_trim_rcsum(skb, len);
nf_bridge_put(skb->nf_bridge);
if (!nf_bridge_alloc(skb))
return NF_DROP;
if (!setup_pre_routing(skb))
return NF_DROP;
store_orig_dstaddr(skb);
NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
br_nf_pre_routing_finish);
return NF_STOLEN;
inhdr_error:
// IP_INC_STATS_BH(IpInHdrErrors);
out:
return NF_DROP;
}
/* PF_BRIDGE/LOCAL_IN ************************************************/
/* The packet is locally destined, which requires a real
* dst_entry, so detach the fake one. On the way up, the
* packet would pass through PRE_ROUTING again (which already
* took place when the packet entered the bridge), but we
* register an IPv4 PRE_ROUTING 'sabotage' hook that will
* prevent this from happening. */
static unsigned int br_nf_local_in(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
if (skb->dst == (struct dst_entry *)&__fake_rtable) {
dst_release(skb->dst);
skb->dst = NULL;
}
return NF_ACCEPT;
}
/* PF_BRIDGE/FORWARD *************************************************/
static int br_nf_forward_finish(struct sk_buff *skb)
{
struct nf_bridge_info *nf_bridge = skb->nf_bridge;
struct net_device *in;
if (skb->protocol != htons(ETH_P_ARP) && !IS_VLAN_ARP(skb)) {
in = nf_bridge->physindev;
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
} else {
in = *((struct net_device **)(skb->cb));
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_FORWARD, skb, in,
skb->dev, br_forward_finish, 1);
return 0;
}
/* This is the 'purely bridged' case. For IP, we pass the packet to
* netfilter with indev and outdev set to the bridge device,
* but we are still able to filter on the 'real' indev/outdev
* because of the physdev module. For ARP, indev and outdev are the
* bridge ports. */
static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge;
struct net_device *parent;
int pf;
if (!skb->nf_bridge)
return NF_ACCEPT;
parent = bridge_parent(out);
if (!parent)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(*pskb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
nf_bridge = skb->nf_bridge;
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
/* The physdev module checks on this */
nf_bridge->mask |= BRNF_BRIDGED;
nf_bridge->physoutdev = skb->dev;
NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
br_nf_forward_finish);
return NF_STOLEN;
}
static unsigned int br_nf_forward_arp(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct net_device **d = (struct net_device **)(skb->cb);
#ifdef CONFIG_SYSCTL
if (!brnf_call_arptables)
return NF_ACCEPT;
#endif
if (skb->protocol != htons(ETH_P_ARP)) {
if (!IS_VLAN_ARP(skb))
return NF_ACCEPT;
skb_pull(*pskb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
if (skb->nh.arph->ar_pln != 4) {
if (IS_VLAN_ARP(skb)) {
skb_push(*pskb, VLAN_HLEN);
(*pskb)->nh.raw -= VLAN_HLEN;
}
return NF_ACCEPT;
}
*d = (struct net_device *)in;
NF_HOOK(NF_ARP, NF_ARP_FORWARD, skb, (struct net_device *)in,
(struct net_device *)out, br_nf_forward_finish);
return NF_STOLEN;
}
/* PF_BRIDGE/LOCAL_OUT ***********************************************/
static int br_nf_local_out_finish(struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK_THRESH(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
br_forward_finish, NF_BR_PRI_FIRST + 1);
return 0;
}
/* This function sees both locally originated IP packets and forwarded
* IP packets (in both cases the destination device is a bridge
* device). It also sees bridged-and-DNAT'ed packets.
* To be able to filter on the physical bridge devices (with the physdev
* module), we steal packets destined to a bridge device away from the
* PF_INET/FORWARD and PF_INET/OUTPUT hook functions, and give them back later,
* when we have determined the real output device. This is done in here.
*
* If (nf_bridge->mask & BRNF_BRIDGED_DNAT) then the packet is bridged
* and we fake the PF_BRIDGE/FORWARD hook. The function br_nf_forward()
* will then fake the PF_INET/FORWARD hook. br_nf_local_out() has priority
* NF_BR_PRI_FIRST, so no relevant PF_BRIDGE/INPUT functions have been nor
* will be executed.
* Otherwise, if nf_bridge->physindev is NULL, the bridge-nf code never touched
* this packet before, and so the packet was locally originated. We fake
* the PF_INET/LOCAL_OUT hook.
* Finally, if nf_bridge->physindev isn't NULL, then the packet was IP routed,
* so we fake the PF_INET/FORWARD hook. ip_sabotage_out() makes sure
* even routed packets that didn't arrive on a bridge interface have their
* nf_bridge->physindev set. */
static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct net_device *realindev, *realoutdev;
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge;
int pf;
if (!skb->nf_bridge)
return NF_ACCEPT;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
#ifdef CONFIG_NETFILTER_DEBUG
/* Sometimes we get packets with NULL ->dst here (for example,
* running a dhcp client daemon triggers this). This should now
* be fixed, but let's keep the check around. */
if (skb->dst == NULL) {
printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
return NF_ACCEPT;
}
#endif
nf_bridge = skb->nf_bridge;
nf_bridge->physoutdev = skb->dev;
realindev = nf_bridge->physindev;
/* Bridged, take PF_BRIDGE/FORWARD.
* (see big note in front of br_nf_pre_routing_finish) */
if (nf_bridge->mask & BRNF_BRIDGED_DNAT) {
if (nf_bridge->mask & BRNF_PKT_TYPE) {
skb->pkt_type = PACKET_OTHERHOST;
nf_bridge->mask ^= BRNF_PKT_TYPE;
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_push(skb, VLAN_HLEN);
skb->nh.raw -= VLAN_HLEN;
}
NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, realindev,
skb->dev, br_forward_finish);
goto out;
}
realoutdev = bridge_parent(skb->dev);
if (!realoutdev)
return NF_DROP;
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* iptables should match -o br0.x */
if (nf_bridge->netoutdev)
realoutdev = nf_bridge->netoutdev;
#endif
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
(*pskb)->nh.raw += VLAN_HLEN;
}
/* IP forwarded traffic has a physindev, locally
* generated traffic hasn't. */
if (realindev != NULL) {
if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT)) {
struct net_device *parent = bridge_parent(realindev);
if (parent)
realindev = parent;
}
NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
realoutdev, br_nf_local_out_finish,
NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD + 1);
} else {
NF_HOOK_THRESH(pf, NF_IP_LOCAL_OUT, skb, realindev,
realoutdev, br_nf_local_out_finish,
NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT + 1);
}
out:
return NF_STOLEN;
}
static int br_nf_dev_queue_xmit(struct sk_buff *skb)
{
if (skb->protocol == htons(ETH_P_IP) &&
skb->len > skb->dev->mtu &&
!skb_shinfo(skb)->gso_size)
return ip_fragment(skb, br_dev_queue_push_xmit);
else
return br_dev_queue_push_xmit(skb);
}
/* PF_BRIDGE/POST_ROUTING ********************************************/
static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
struct nf_bridge_info *nf_bridge = (*pskb)->nf_bridge;
struct net_device *realoutdev = bridge_parent(skb->dev);
int pf;
#ifdef CONFIG_NETFILTER_DEBUG
/* Be very paranoid. This probably won't happen anymore, but let's
* keep the check just to be sure... */
if (skb->mac.raw < skb->head || skb->mac.raw + ETH_HLEN > skb->data) {
printk(KERN_CRIT "br_netfilter: Argh!! br_nf_post_routing: "
"bad mac.raw pointer.");
goto print_error;
}
#endif
if (!nf_bridge)
return NF_ACCEPT;
if (!realoutdev)
return NF_DROP;
if (skb->protocol == htons(ETH_P_IP) || IS_VLAN_IP(skb))
pf = PF_INET;
else
pf = PF_INET6;
#ifdef CONFIG_NETFILTER_DEBUG
if (skb->dst == NULL) {
printk(KERN_CRIT "br_netfilter: skb->dst == NULL.");
goto print_error;
}
#endif
/* We assume any code from br_dev_queue_push_xmit onwards doesn't care
* about the value of skb->pkt_type. */
if (skb->pkt_type == PACKET_OTHERHOST) {
skb->pkt_type = PACKET_HOST;
nf_bridge->mask |= BRNF_PKT_TYPE;
}
if (skb->protocol == htons(ETH_P_8021Q)) {
skb_pull(skb, VLAN_HLEN);
skb->nh.raw += VLAN_HLEN;
}
nf_bridge_save_header(skb);
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
if (nf_bridge->netoutdev)
realoutdev = nf_bridge->netoutdev;
#endif
NF_HOOK(pf, NF_IP_POST_ROUTING, skb, NULL, realoutdev,
br_nf_dev_queue_xmit);
return NF_STOLEN;
#ifdef CONFIG_NETFILTER_DEBUG
print_error:
if (skb->dev != NULL) {
printk("[%s]", skb->dev->name);
if (realoutdev)
printk("[%s]", realoutdev->name);
}
printk(" head:%p, raw:%p, data:%p\n", skb->head, skb->mac.raw,
skb->data);
return NF_ACCEPT;
#endif
}
/* IP/SABOTAGE *****************************************************/
/* Don't hand locally destined packets to PF_INET(6)/PRE_ROUTING
* for the second time. */
static unsigned int ip_sabotage_in(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
if ((*pskb)->nf_bridge &&
!((*pskb)->nf_bridge->mask & BRNF_NF_BRIDGE_PREROUTING)) {
return NF_STOP;
}
return NF_ACCEPT;
}
/* Postpone execution of PF_INET(6)/FORWARD, PF_INET(6)/LOCAL_OUT
* and PF_INET(6)/POST_ROUTING until we have done the forwarding
* decision in the bridge code and have determined nf_bridge->physoutdev. */
static unsigned int ip_sabotage_out(unsigned int hook, struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct sk_buff *skb = *pskb;
if ((out->hard_start_xmit == br_dev_xmit &&
okfn != br_nf_forward_finish &&
okfn != br_nf_local_out_finish && okfn != br_nf_dev_queue_xmit)
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
|| ((out->priv_flags & IFF_802_1Q_VLAN) &&
VLAN_DEV_INFO(out)->real_dev->hard_start_xmit == br_dev_xmit)
#endif
) {
struct nf_bridge_info *nf_bridge;
if (!skb->nf_bridge) {
#ifdef CONFIG_SYSCTL
/* This code is executed while in the IP(v6) stack,
the version should be 4 or 6. We can't use
skb->protocol because that isn't set on
PF_INET(6)/LOCAL_OUT. */
struct iphdr *ip = skb->nh.iph;
if (ip->version == 4 && !brnf_call_iptables)
return NF_ACCEPT;
else if (ip->version == 6 && !brnf_call_ip6tables)
return NF_ACCEPT;
#endif
if (hook == NF_IP_POST_ROUTING)
return NF_ACCEPT;
if (!nf_bridge_alloc(skb))
return NF_DROP;
}
nf_bridge = skb->nf_bridge;
/* This frame will arrive on PF_BRIDGE/LOCAL_OUT and we
* will need the indev then. For a brouter, the real indev
* can be a bridge port, so we make sure br_nf_local_out()
* doesn't use the bridge parent of the indev by using
* the BRNF_DONT_TAKE_PARENT mask. */
if (hook == NF_IP_FORWARD && nf_bridge->physindev == NULL) {
nf_bridge->mask |= BRNF_DONT_TAKE_PARENT;
nf_bridge->physindev = (struct net_device *)in;
}
#if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
/* the iptables outdev is br0.x, not br0 */
if (out->priv_flags & IFF_802_1Q_VLAN)
nf_bridge->netoutdev = (struct net_device *)out;
#endif
return NF_STOP;
}
return NF_ACCEPT;
}
/* For br_nf_local_out we need (prio = NF_BR_PRI_FIRST), to insure that innocent
* PF_BRIDGE/NF_BR_LOCAL_OUT functions don't get bridged traffic as input.
* For br_nf_post_routing, we need (prio = NF_BR_PRI_LAST), because
* ip_refrag() can return NF_STOLEN. */
static struct nf_hook_ops br_nf_ops[] = {
{ .hook = br_nf_pre_routing,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_PRE_ROUTING,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_local_in,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_LOCAL_IN,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_forward_ip,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_FORWARD,
.priority = NF_BR_PRI_BRNF - 1, },
{ .hook = br_nf_forward_arp,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_FORWARD,
.priority = NF_BR_PRI_BRNF, },
{ .hook = br_nf_local_out,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_LOCAL_OUT,
.priority = NF_BR_PRI_FIRST, },
{ .hook = br_nf_post_routing,
.owner = THIS_MODULE,
.pf = PF_BRIDGE,
.hooknum = NF_BR_POST_ROUTING,
.priority = NF_BR_PRI_LAST, },
{ .hook = ip_sabotage_in,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_PRE_ROUTING,
.priority = NF_IP_PRI_FIRST, },
{ .hook = ip_sabotage_in,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_PRE_ROUTING,
.priority = NF_IP6_PRI_FIRST, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_FORWARD,
.priority = NF_IP_PRI_BRIDGE_SABOTAGE_FORWARD, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_FORWARD,
.priority = NF_IP6_PRI_BRIDGE_SABOTAGE_FORWARD, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_LOCAL_OUT,
.priority = NF_IP_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_LOCAL_OUT,
.priority = NF_IP6_PRI_BRIDGE_SABOTAGE_LOCAL_OUT, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET,
.hooknum = NF_IP_POST_ROUTING,
.priority = NF_IP_PRI_FIRST, },
{ .hook = ip_sabotage_out,
.owner = THIS_MODULE,
.pf = PF_INET6,
.hooknum = NF_IP6_POST_ROUTING,
.priority = NF_IP6_PRI_FIRST, },
};
#ifdef CONFIG_SYSCTL
static