-
Notifications
You must be signed in to change notification settings - Fork 102
/
ip_gre.c
1789 lines (1484 loc) · 45.8 KB
/
ip_gre.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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Linux NET3: GRE over IP protocol decoder.
*
* Authors: Alexey Kuznetsov (kuznet@ms2.inr.ac.ru)
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/capability.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
#include <linux/init.h>
#include <linux/in6.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/netfilter_ipv4.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <net/sock.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/ip_tunnels.h>
#include <net/arp.h>
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/rtnetlink.h>
#include <net/gre.h>
#include <net/dst_metadata.h>
#include <net/erspan.h>
/*
Problems & solutions
--------------------
1. The most important issue is detecting local dead loops.
They would cause complete host lockup in transmit, which
would be "resolved" by stack overflow or, if queueing is enabled,
with infinite looping in net_bh.
We cannot track such dead loops during route installation,
it is infeasible task. The most general solutions would be
to keep skb->encapsulation counter (sort of local ttl),
and silently drop packet when it expires. It is a good
solution, but it supposes maintaining new variable in ALL
skb, even if no tunneling is used.
Current solution: xmit_recursion breaks dead loops. This is a percpu
counter, since when we enter the first ndo_xmit(), cpu migration is
forbidden. We force an exit if this counter reaches RECURSION_LIMIT
2. Networking dead loops would not kill routers, but would really
kill network. IP hop limit plays role of "t->recursion" in this case,
if we copy it from packet being encapsulated to upper header.
It is very good solution, but it introduces two problems:
- Routing protocols, using packets with ttl=1 (OSPF, RIP2),
do not work over tunnels.
- traceroute does not work. I planned to relay ICMP from tunnel,
so that this problem would be solved and traceroute output
would even more informative. This idea appeared to be wrong:
only Linux complies to rfc1812 now (yes, guys, Linux is the only
true router now :-)), all routers (at least, in neighbourhood of mine)
return only 8 bytes of payload. It is the end.
Hence, if we want that OSPF worked or traceroute said something reasonable,
we should search for another solution.
One of them is to parse packet trying to detect inner encapsulation
made by our node. It is difficult or even impossible, especially,
taking into account fragmentation. TO be short, ttl is not solution at all.
Current solution: The solution was UNEXPECTEDLY SIMPLE.
We force DF flag on tunnels with preconfigured hop limit,
that is ALL. :-) Well, it does not remove the problem completely,
but exponential growth of network traffic is changed to linear
(branches, that exceed pmtu are pruned) and tunnel mtu
rapidly degrades to value <68, where looping stops.
Yes, it is not good if there exists a router in the loop,
which does not force DF, even when encapsulating packets have DF set.
But it is not our problem! Nobody could accuse us, we made
all that we could make. Even if it is your gated who injected
fatal route to network, even if it were you who configured
fatal static route: you are innocent. :-)
Alexey Kuznetsov.
*/
static bool log_ecn_error = true;
module_param(log_ecn_error, bool, 0644);
MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
static struct rtnl_link_ops ipgre_link_ops __read_mostly;
static const struct header_ops ipgre_header_ops;
static int ipgre_tunnel_init(struct net_device *dev);
static void erspan_build_header(struct sk_buff *skb,
u32 id, u32 index,
bool truncate, bool is_ipv4);
static unsigned int ipgre_net_id __read_mostly;
static unsigned int gre_tap_net_id __read_mostly;
static unsigned int erspan_net_id __read_mostly;
static int ipgre_err(struct sk_buff *skb, u32 info,
const struct tnl_ptk_info *tpi)
{
/* All the routers (except for Linux) return only
8 bytes of packet payload. It means, that precise relaying of
ICMP in the real Internet is absolutely infeasible.
Moreover, Cisco "wise men" put GRE key to the third word
in GRE header. It makes impossible maintaining even soft
state for keyed GRE tunnels with enabled checksum. Tell
them "thank you".
Well, I wonder, rfc1812 was written by Cisco employee,
what the hell these idiots break standards established
by themselves???
*/
struct net *net = dev_net(skb->dev);
struct ip_tunnel_net *itn;
const struct iphdr *iph;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
unsigned int data_len = 0;
struct ip_tunnel *t;
if (tpi->proto == htons(ETH_P_TEB))
itn = net_generic(net, gre_tap_net_id);
else if (tpi->proto == htons(ETH_P_ERSPAN) ||
tpi->proto == htons(ETH_P_ERSPAN2))
itn = net_generic(net, erspan_net_id);
else
itn = net_generic(net, ipgre_net_id);
iph = (const struct iphdr *)(icmp_hdr(skb) + 1);
t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
iph->daddr, iph->saddr, tpi->key);
if (!t)
return -ENOENT;
switch (type) {
default:
case ICMP_PARAMETERPROB:
return 0;
case ICMP_DEST_UNREACH:
switch (code) {
case ICMP_SR_FAILED:
case ICMP_PORT_UNREACH:
/* Impossible event. */
return 0;
default:
/* All others are translated to HOST_UNREACH.
rfc2003 contains "deep thoughts" about NET_UNREACH,
I believe they are just ether pollution. --ANK
*/
break;
}
break;
case ICMP_TIME_EXCEEDED:
if (code != ICMP_EXC_TTL)
return 0;
data_len = icmp_hdr(skb)->un.reserved[1] * 4; /* RFC 4884 4.1 */
break;
case ICMP_REDIRECT:
break;
}
#if IS_ENABLED(CONFIG_IPV6)
if (tpi->proto == htons(ETH_P_IPV6) &&
!ip6_err_gen_icmpv6_unreach(skb, iph->ihl * 4 + tpi->hdr_len,
type, data_len))
return 0;
#endif
if (t->parms.iph.daddr == 0 ||
ipv4_is_multicast(t->parms.iph.daddr))
return 0;
if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
return 0;
if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
t->err_count++;
else
t->err_count = 1;
t->err_time = jiffies;
return 0;
}
static void gre_err(struct sk_buff *skb, u32 info)
{
/* All the routers (except for Linux) return only
* 8 bytes of packet payload. It means, that precise relaying of
* ICMP in the real Internet is absolutely infeasible.
*
* Moreover, Cisco "wise men" put GRE key to the third word
* in GRE header. It makes impossible maintaining even soft
* state for keyed
* GRE tunnels with enabled checksum. Tell them "thank you".
*
* Well, I wonder, rfc1812 was written by Cisco employee,
* what the hell these idiots break standards established
* by themselves???
*/
const struct iphdr *iph = (struct iphdr *)skb->data;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct tnl_ptk_info tpi;
if (gre_parse_header(skb, &tpi, NULL, htons(ETH_P_IP),
iph->ihl * 4) < 0)
return;
if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
ipv4_update_pmtu(skb, dev_net(skb->dev), info,
skb->dev->ifindex, IPPROTO_GRE);
return;
}
if (type == ICMP_REDIRECT) {
ipv4_redirect(skb, dev_net(skb->dev), skb->dev->ifindex,
IPPROTO_GRE);
return;
}
ipgre_err(skb, info, &tpi);
}
static bool is_erspan_type1(int gre_hdr_len)
{
/* Both ERSPAN type I (version 0) and type II (version 1) use
* protocol 0x88BE, but the type I has only 4-byte GRE header,
* while type II has 8-byte.
*/
return gre_hdr_len == 4;
}
static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
int gre_hdr_len)
{
struct net *net = dev_net(skb->dev);
struct metadata_dst *tun_dst = NULL;
struct erspan_base_hdr *ershdr;
struct ip_tunnel_net *itn;
struct ip_tunnel *tunnel;
const struct iphdr *iph;
struct erspan_md2 *md2;
int ver;
int len;
itn = net_generic(net, erspan_net_id);
iph = ip_hdr(skb);
if (is_erspan_type1(gre_hdr_len)) {
ver = 0;
tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
tpi->flags | TUNNEL_NO_KEY,
iph->saddr, iph->daddr, 0);
} else {
ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len);
ver = ershdr->ver;
tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
tpi->flags | TUNNEL_KEY,
iph->saddr, iph->daddr, tpi->key);
}
if (tunnel) {
if (is_erspan_type1(gre_hdr_len))
len = gre_hdr_len;
else
len = gre_hdr_len + erspan_hdr_len(ver);
if (unlikely(!pskb_may_pull(skb, len)))
return PACKET_REJECT;
if (__iptunnel_pull_header(skb,
len,
htons(ETH_P_TEB),
false, false) < 0)
goto drop;
if (tunnel->collect_md) {
struct erspan_metadata *pkt_md, *md;
struct ip_tunnel_info *info;
unsigned char *gh;
__be64 tun_id;
__be16 flags;
tpi->flags |= TUNNEL_KEY;
flags = tpi->flags;
tun_id = key32_to_tunnel_id(tpi->key);
tun_dst = ip_tun_rx_dst(skb, flags,
tun_id, sizeof(*md));
if (!tun_dst)
return PACKET_REJECT;
/* skb can be uncloned in __iptunnel_pull_header, so
* old pkt_md is no longer valid and we need to reset
* it
*/
gh = skb_network_header(skb) +
skb_network_header_len(skb);
pkt_md = (struct erspan_metadata *)(gh + gre_hdr_len +
sizeof(*ershdr));
md = ip_tunnel_info_opts(&tun_dst->u.tun_info);
md->version = ver;
md2 = &md->u.md2;
memcpy(md2, pkt_md, ver == 1 ? ERSPAN_V1_MDSIZE :
ERSPAN_V2_MDSIZE);
info = &tun_dst->u.tun_info;
info->key.tun_flags |= TUNNEL_ERSPAN_OPT;
info->options_len = sizeof(*md);
}
skb_reset_mac_header(skb);
ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
return PACKET_RCVD;
}
return PACKET_REJECT;
drop:
kfree_skb(skb);
return PACKET_RCVD;
}
static int __ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
struct ip_tunnel_net *itn, int hdr_len, bool raw_proto)
{
struct metadata_dst *tun_dst = NULL;
const struct iphdr *iph;
struct ip_tunnel *tunnel;
iph = ip_hdr(skb);
tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
iph->saddr, iph->daddr, tpi->key);
if (tunnel) {
const struct iphdr *tnl_params;
if (__iptunnel_pull_header(skb, hdr_len, tpi->proto,
raw_proto, false) < 0)
goto drop;
/* Special case for ipgre_header_parse(), which expects the
* mac_header to point to the outer IP header.
*/
if (tunnel->dev->header_ops == &ipgre_header_ops)
skb_pop_mac_header(skb);
else
skb_reset_mac_header(skb);
tnl_params = &tunnel->parms.iph;
if (tunnel->collect_md || tnl_params->daddr == 0) {
__be16 flags;
__be64 tun_id;
flags = tpi->flags & (TUNNEL_CSUM | TUNNEL_KEY);
tun_id = key32_to_tunnel_id(tpi->key);
tun_dst = ip_tun_rx_dst(skb, flags, tun_id, 0);
if (!tun_dst)
return PACKET_REJECT;
}
ip_tunnel_rcv(tunnel, skb, tpi, tun_dst, log_ecn_error);
return PACKET_RCVD;
}
return PACKET_NEXT;
drop:
kfree_skb(skb);
return PACKET_RCVD;
}
static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi,
int hdr_len)
{
struct net *net = dev_net(skb->dev);
struct ip_tunnel_net *itn;
int res;
if (tpi->proto == htons(ETH_P_TEB))
itn = net_generic(net, gre_tap_net_id);
else
itn = net_generic(net, ipgre_net_id);
res = __ipgre_rcv(skb, tpi, itn, hdr_len, false);
if (res == PACKET_NEXT && tpi->proto == htons(ETH_P_TEB)) {
/* ipgre tunnels in collect metadata mode should receive
* also ETH_P_TEB traffic.
*/
itn = net_generic(net, ipgre_net_id);
res = __ipgre_rcv(skb, tpi, itn, hdr_len, true);
}
return res;
}
static int gre_rcv(struct sk_buff *skb)
{
struct tnl_ptk_info tpi;
bool csum_err = false;
int hdr_len;
#ifdef CONFIG_NET_IPGRE_BROADCAST
if (ipv4_is_multicast(ip_hdr(skb)->daddr)) {
/* Looped back packet, drop it! */
if (rt_is_output_route(skb_rtable(skb)))
goto drop;
}
#endif
hdr_len = gre_parse_header(skb, &tpi, &csum_err, htons(ETH_P_IP), 0);
if (hdr_len < 0)
goto drop;
if (unlikely(tpi.proto == htons(ETH_P_ERSPAN) ||
tpi.proto == htons(ETH_P_ERSPAN2))) {
if (erspan_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
return 0;
goto out;
}
if (ipgre_rcv(skb, &tpi, hdr_len) == PACKET_RCVD)
return 0;
out:
icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
drop:
kfree_skb(skb);
return 0;
}
static void __gre_xmit(struct sk_buff *skb, struct net_device *dev,
const struct iphdr *tnl_params,
__be16 proto)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
__be16 flags = tunnel->parms.o_flags;
/* Push GRE header. */
gre_build_header(skb, tunnel->tun_hlen,
flags, proto, tunnel->parms.o_key,
(flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno)) : 0);
ip_tunnel_xmit(skb, dev, tnl_params, tnl_params->protocol);
}
static int gre_handle_offloads(struct sk_buff *skb, bool csum)
{
return iptunnel_handle_offloads(skb, csum ? SKB_GSO_GRE_CSUM : SKB_GSO_GRE);
}
static void gre_fb_xmit(struct sk_buff *skb, struct net_device *dev,
__be16 proto)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct ip_tunnel_info *tun_info;
const struct ip_tunnel_key *key;
int tunnel_hlen;
__be16 flags;
tun_info = skb_tunnel_info(skb);
if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
ip_tunnel_info_af(tun_info) != AF_INET))
goto err_free_skb;
key = &tun_info->key;
tunnel_hlen = gre_calc_hlen(key->tun_flags);
if (skb_cow_head(skb, dev->needed_headroom))
goto err_free_skb;
/* Push Tunnel header. */
if (gre_handle_offloads(skb, !!(tun_info->key.tun_flags & TUNNEL_CSUM)))
goto err_free_skb;
flags = tun_info->key.tun_flags &
(TUNNEL_CSUM | TUNNEL_KEY | TUNNEL_SEQ);
gre_build_header(skb, tunnel_hlen, flags, proto,
tunnel_id_to_key32(tun_info->key.tun_id),
(flags & TUNNEL_SEQ) ? htonl(atomic_fetch_inc(&tunnel->o_seqno)) : 0);
ip_md_tunnel_xmit(skb, dev, IPPROTO_GRE, tunnel_hlen);
return;
err_free_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
}
static void erspan_fb_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct ip_tunnel_info *tun_info;
const struct ip_tunnel_key *key;
struct erspan_metadata *md;
bool truncate = false;
__be16 proto;
int tunnel_hlen;
int version;
int nhoff;
int thoff;
tun_info = skb_tunnel_info(skb);
if (unlikely(!tun_info || !(tun_info->mode & IP_TUNNEL_INFO_TX) ||
ip_tunnel_info_af(tun_info) != AF_INET))
goto err_free_skb;
key = &tun_info->key;
if (!(tun_info->key.tun_flags & TUNNEL_ERSPAN_OPT))
goto err_free_skb;
if (tun_info->options_len < sizeof(*md))
goto err_free_skb;
md = ip_tunnel_info_opts(tun_info);
/* ERSPAN has fixed 8 byte GRE header */
version = md->version;
tunnel_hlen = 8 + erspan_hdr_len(version);
if (skb_cow_head(skb, dev->needed_headroom))
goto err_free_skb;
if (gre_handle_offloads(skb, false))
goto err_free_skb;
if (skb->len > dev->mtu + dev->hard_header_len) {
pskb_trim(skb, dev->mtu + dev->hard_header_len);
truncate = true;
}
nhoff = skb_network_header(skb) - skb_mac_header(skb);
if (skb->protocol == htons(ETH_P_IP) &&
(ntohs(ip_hdr(skb)->tot_len) > skb->len - nhoff))
truncate = true;
thoff = skb_transport_header(skb) - skb_mac_header(skb);
if (skb->protocol == htons(ETH_P_IPV6) &&
(ntohs(ipv6_hdr(skb)->payload_len) > skb->len - thoff))
truncate = true;
if (version == 1) {
erspan_build_header(skb, ntohl(tunnel_id_to_key32(key->tun_id)),
ntohl(md->u.index), truncate, true);
proto = htons(ETH_P_ERSPAN);
} else if (version == 2) {
erspan_build_header_v2(skb,
ntohl(tunnel_id_to_key32(key->tun_id)),
md->u.md2.dir,
get_hwid(&md->u.md2),
truncate, true);
proto = htons(ETH_P_ERSPAN2);
} else {
goto err_free_skb;
}
gre_build_header(skb, 8, TUNNEL_SEQ,
proto, 0, htonl(atomic_fetch_inc(&tunnel->o_seqno)));
ip_md_tunnel_xmit(skb, dev, IPPROTO_GRE, tunnel_hlen);
return;
err_free_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
}
static int gre_fill_metadata_dst(struct net_device *dev, struct sk_buff *skb)
{
struct ip_tunnel_info *info = skb_tunnel_info(skb);
const struct ip_tunnel_key *key;
struct rtable *rt;
struct flowi4 fl4;
if (ip_tunnel_info_af(info) != AF_INET)
return -EINVAL;
key = &info->key;
ip_tunnel_init_flow(&fl4, IPPROTO_GRE, key->u.ipv4.dst, key->u.ipv4.src,
tunnel_id_to_key32(key->tun_id),
key->tos & ~INET_ECN_MASK, 0, skb->mark,
skb_get_hash(skb));
rt = ip_route_output_key(dev_net(dev), &fl4);
if (IS_ERR(rt))
return PTR_ERR(rt);
ip_rt_put(rt);
info->key.u.ipv4.src = fl4.saddr;
return 0;
}
static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
const struct iphdr *tnl_params;
if (!pskb_inet_may_pull(skb))
goto free_skb;
if (tunnel->collect_md) {
gre_fb_xmit(skb, dev, skb->protocol);
return NETDEV_TX_OK;
}
if (dev->header_ops) {
const int pull_len = tunnel->hlen + sizeof(struct iphdr);
if (skb_cow_head(skb, 0))
goto free_skb;
tnl_params = (const struct iphdr *)skb->data;
if (pull_len > skb_transport_offset(skb))
goto free_skb;
/* Pull skb since ip_tunnel_xmit() needs skb->data pointing
* to gre header.
*/
skb_pull(skb, pull_len);
skb_reset_mac_header(skb);
} else {
if (skb_cow_head(skb, dev->needed_headroom))
goto free_skb;
tnl_params = &tunnel->parms.iph;
}
if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
goto free_skb;
__gre_xmit(skb, dev, tnl_params, skb->protocol);
return NETDEV_TX_OK;
free_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
return NETDEV_TX_OK;
}
static netdev_tx_t erspan_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
bool truncate = false;
__be16 proto;
if (!pskb_inet_may_pull(skb))
goto free_skb;
if (tunnel->collect_md) {
erspan_fb_xmit(skb, dev);
return NETDEV_TX_OK;
}
if (gre_handle_offloads(skb, false))
goto free_skb;
if (skb_cow_head(skb, dev->needed_headroom))
goto free_skb;
if (skb->len > dev->mtu + dev->hard_header_len) {
pskb_trim(skb, dev->mtu + dev->hard_header_len);
truncate = true;
}
/* Push ERSPAN header */
if (tunnel->erspan_ver == 0) {
proto = htons(ETH_P_ERSPAN);
tunnel->parms.o_flags &= ~TUNNEL_SEQ;
} else if (tunnel->erspan_ver == 1) {
erspan_build_header(skb, ntohl(tunnel->parms.o_key),
tunnel->index,
truncate, true);
proto = htons(ETH_P_ERSPAN);
} else if (tunnel->erspan_ver == 2) {
erspan_build_header_v2(skb, ntohl(tunnel->parms.o_key),
tunnel->dir, tunnel->hwid,
truncate, true);
proto = htons(ETH_P_ERSPAN2);
} else {
goto free_skb;
}
tunnel->parms.o_flags &= ~TUNNEL_KEY;
__gre_xmit(skb, dev, &tunnel->parms.iph, proto);
return NETDEV_TX_OK;
free_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
return NETDEV_TX_OK;
}
static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
if (!pskb_inet_may_pull(skb))
goto free_skb;
if (tunnel->collect_md) {
gre_fb_xmit(skb, dev, htons(ETH_P_TEB));
return NETDEV_TX_OK;
}
if (gre_handle_offloads(skb, !!(tunnel->parms.o_flags & TUNNEL_CSUM)))
goto free_skb;
if (skb_cow_head(skb, dev->needed_headroom))
goto free_skb;
__gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_TEB));
return NETDEV_TX_OK;
free_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
return NETDEV_TX_OK;
}
static void ipgre_link_update(struct net_device *dev, bool set_mtu)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
int len;
len = tunnel->tun_hlen;
tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
len = tunnel->tun_hlen - len;
tunnel->hlen = tunnel->hlen + len;
if (dev->header_ops)
dev->hard_header_len += len;
else
dev->needed_headroom += len;
if (set_mtu)
dev->mtu = max_t(int, dev->mtu - len, 68);
if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
tunnel->encap.type == TUNNEL_ENCAP_NONE) {
dev->features |= NETIF_F_GSO_SOFTWARE;
dev->hw_features |= NETIF_F_GSO_SOFTWARE;
} else {
dev->features &= ~NETIF_F_GSO_SOFTWARE;
dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
}
dev->features |= NETIF_F_LLTX;
} else {
dev->hw_features &= ~NETIF_F_GSO_SOFTWARE;
dev->features &= ~(NETIF_F_LLTX | NETIF_F_GSO_SOFTWARE);
}
}
static int ipgre_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p,
int cmd)
{
int err;
if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
if (p->iph.version != 4 || p->iph.protocol != IPPROTO_GRE ||
p->iph.ihl != 5 || (p->iph.frag_off & htons(~IP_DF)) ||
((p->i_flags | p->o_flags) & (GRE_VERSION | GRE_ROUTING)))
return -EINVAL;
}
p->i_flags = gre_flags_to_tnl_flags(p->i_flags);
p->o_flags = gre_flags_to_tnl_flags(p->o_flags);
err = ip_tunnel_ctl(dev, p, cmd);
if (err)
return err;
if (cmd == SIOCCHGTUNNEL) {
struct ip_tunnel *t = netdev_priv(dev);
t->parms.i_flags = p->i_flags;
t->parms.o_flags = p->o_flags;
if (strcmp(dev->rtnl_link_ops->kind, "erspan"))
ipgre_link_update(dev, true);
}
p->i_flags = gre_tnl_flags_to_gre_flags(p->i_flags);
p->o_flags = gre_tnl_flags_to_gre_flags(p->o_flags);
return 0;
}
/* Nice toy. Unfortunately, useless in real life :-)
It allows to construct virtual multiprotocol broadcast "LAN"
over the Internet, provided multicast routing is tuned.
I have no idea was this bicycle invented before me,
so that I had to set ARPHRD_IPGRE to a random value.
I have an impression, that Cisco could make something similar,
but this feature is apparently missing in IOS<=11.2(8).
I set up 10.66.66/24 and fec0:6666:6666::0/96 as virtual networks
with broadcast 224.66.66.66. If you have access to mbone, play with me :-)
ping -t 255 224.66.66.66
If nobody answers, mbone does not work.
ip tunnel add Universe mode gre remote 224.66.66.66 local <Your_real_addr> ttl 255
ip addr add 10.66.66.<somewhat>/24 dev Universe
ifconfig Universe up
ifconfig Universe add fe80::<Your_real_addr>/10
ifconfig Universe add fec0:6666:6666::<Your_real_addr>/96
ftp 10.66.66.66
...
ftp fec0:6666:6666::193.233.7.65
...
*/
static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
unsigned short type,
const void *daddr, const void *saddr, unsigned int len)
{
struct ip_tunnel *t = netdev_priv(dev);
struct iphdr *iph;
struct gre_base_hdr *greh;
iph = skb_push(skb, t->hlen + sizeof(*iph));
greh = (struct gre_base_hdr *)(iph+1);
greh->flags = gre_tnl_flags_to_gre_flags(t->parms.o_flags);
greh->protocol = htons(type);
memcpy(iph, &t->parms.iph, sizeof(struct iphdr));
/* Set the source hardware address. */
if (saddr)
memcpy(&iph->saddr, saddr, 4);
if (daddr)
memcpy(&iph->daddr, daddr, 4);
if (iph->daddr)
return t->hlen + sizeof(*iph);
return -(t->hlen + sizeof(*iph));
}
static int ipgre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
{
const struct iphdr *iph = (const struct iphdr *) skb_mac_header(skb);
memcpy(haddr, &iph->saddr, 4);
return 4;
}
static const struct header_ops ipgre_header_ops = {
.create = ipgre_header,
.parse = ipgre_header_parse,
};
#ifdef CONFIG_NET_IPGRE_BROADCAST
static int ipgre_open(struct net_device *dev)
{
struct ip_tunnel *t = netdev_priv(dev);
if (ipv4_is_multicast(t->parms.iph.daddr)) {
struct flowi4 fl4;
struct rtable *rt;
rt = ip_route_output_gre(t->net, &fl4,
t->parms.iph.daddr,
t->parms.iph.saddr,
t->parms.o_key,
RT_TOS(t->parms.iph.tos),
t->parms.link);
if (IS_ERR(rt))
return -EADDRNOTAVAIL;
dev = rt->dst.dev;
ip_rt_put(rt);
if (!__in_dev_get_rtnl(dev))
return -EADDRNOTAVAIL;
t->mlink = dev->ifindex;
ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);
}
return 0;
}
static int ipgre_close(struct net_device *dev)
{
struct ip_tunnel *t = netdev_priv(dev);
if (ipv4_is_multicast(t->parms.iph.daddr) && t->mlink) {
struct in_device *in_dev;
in_dev = inetdev_by_index(t->net, t->mlink);
if (in_dev)
ip_mc_dec_group(in_dev, t->parms.iph.daddr);
}
return 0;
}
#endif
static const struct net_device_ops ipgre_netdev_ops = {
.ndo_init = ipgre_tunnel_init,
.ndo_uninit = ip_tunnel_uninit,
#ifdef CONFIG_NET_IPGRE_BROADCAST
.ndo_open = ipgre_open,
.ndo_stop = ipgre_close,
#endif
.ndo_start_xmit = ipgre_xmit,
.ndo_siocdevprivate = ip_tunnel_siocdevprivate,
.ndo_change_mtu = ip_tunnel_change_mtu,
.ndo_get_stats64 = dev_get_tstats64,
.ndo_get_iflink = ip_tunnel_get_iflink,
.ndo_tunnel_ctl = ipgre_tunnel_ctl,
};
#define GRE_FEATURES (NETIF_F_SG | \
NETIF_F_FRAGLIST | \
NETIF_F_HIGHDMA | \
NETIF_F_HW_CSUM)
static void ipgre_tunnel_setup(struct net_device *dev)
{
dev->netdev_ops = &ipgre_netdev_ops;
dev->type = ARPHRD_IPGRE;
ip_tunnel_setup(dev, ipgre_net_id);
}
static void __gre_tunnel_init(struct net_device *dev)
{
struct ip_tunnel *tunnel;
tunnel = netdev_priv(dev);
tunnel->tun_hlen = gre_calc_hlen(tunnel->parms.o_flags);
tunnel->parms.iph.protocol = IPPROTO_GRE;
tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
dev->needed_headroom = tunnel->hlen + sizeof(tunnel->parms.iph);
dev->features |= GRE_FEATURES;
dev->hw_features |= GRE_FEATURES;
if (!(tunnel->parms.o_flags & TUNNEL_SEQ)) {
/* TCP offload with GRE SEQ is not supported, nor
* can we support 2 levels of outer headers requiring
* an update.
*/
if (!(tunnel->parms.o_flags & TUNNEL_CSUM) ||
(tunnel->encap.type == TUNNEL_ENCAP_NONE)) {
dev->features |= NETIF_F_GSO_SOFTWARE;
dev->hw_features |= NETIF_F_GSO_SOFTWARE;
}
/* Can use a lockless transmit, unless we generate
* output sequences
*/
dev->features |= NETIF_F_LLTX;
}
}
static int ipgre_tunnel_init(struct net_device *dev)
{
struct ip_tunnel *tunnel = netdev_priv(dev);
struct iphdr *iph = &tunnel->parms.iph;
__gre_tunnel_init(dev);
memcpy(dev->dev_addr, &iph->saddr, 4);
memcpy(dev->broadcast, &iph->daddr, 4);
dev->flags = IFF_NOARP;
netif_keep_dst(dev);
dev->addr_len = 4;
if (iph->daddr && !tunnel->collect_md) {
#ifdef CONFIG_NET_IPGRE_BROADCAST
if (ipv4_is_multicast(iph->daddr)) {
if (!iph->saddr)
return -EINVAL;
dev->flags = IFF_BROADCAST;