aboutsummaryrefslogtreecommitdiff
path: root/net/xfrm/xfrm_output.c
blob: e5722c95b8bb38c528cc518cdc3a05e08a338264 (plain)
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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * xfrm_output.c - Common IPsec encapsulation code.
 *
 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <net/dst.h>
#include <net/gso.h>
#include <net/icmp.h>
#include <net/inet_ecn.h>
#include <net/xfrm.h>

#if IS_ENABLED(CONFIG_IPV6)
#include <net/ip6_route.h>
#include <net/ipv6_stubs.h>
#endif

#include "xfrm_inout.h"

static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb);
static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb);

static int xfrm_skb_check_space(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev)
		- skb_headroom(skb);
	int ntail = dst->dev->needed_tailroom - skb_tailroom(skb);

	if (nhead <= 0) {
		if (ntail <= 0)
			return 0;
		nhead = 0;
	} else if (ntail < 0)
		ntail = 0;

	return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC);
}

/* Children define the path of the packet through the
 * Linux networking.  Thus, destinations are stackable.
 */

static struct dst_entry *skb_dst_pop(struct sk_buff *skb)
{
	struct dst_entry *child = dst_clone(xfrm_dst_child(skb_dst(skb)));

	skb_dst_drop(skb);
	return child;
}

/* Add encapsulation header.
 *
 * The IP header will be moved forward to make space for the encapsulation
 * header.
 */
static int xfrm4_transport_output(struct xfrm_state *x, struct sk_buff *skb)
{
	struct iphdr *iph = ip_hdr(skb);
	int ihl = iph->ihl * 4;

	skb_set_inner_transport_header(skb, skb_transport_offset(skb));

	skb_set_network_header(skb, -x->props.header_len);
	skb->mac_header = skb->network_header +
			  offsetof(struct iphdr, protocol);
	skb->transport_header = skb->network_header + ihl;
	__skb_pull(skb, ihl);
	memmove(skb_network_header(skb), iph, ihl);
	return 0;
}

#if IS_ENABLED(CONFIG_IPV6_MIP6)
static int mip6_rthdr_offset(struct sk_buff *skb, u8 **nexthdr, int type)
{
	const unsigned char *nh = skb_network_header(skb);
	unsigned int offset = sizeof(struct ipv6hdr);
	unsigned int packet_len;
	int found_rhdr = 0;

	packet_len = skb_tail_pointer(skb) - nh;
	*nexthdr = &ipv6_hdr(skb)->nexthdr;

	while (offset <= packet_len) {
		struct ipv6_opt_hdr *exthdr;

		switch (**nexthdr) {
		case NEXTHDR_HOP:
			break;
		case NEXTHDR_ROUTING:
			if (type == IPPROTO_ROUTING && offset + 3 <= packet_len) {
				struct ipv6_rt_hdr *rt;

				rt = (struct ipv6_rt_hdr *)(nh + offset);
				if (rt->type != 0)
					return offset;
			}
			found_rhdr = 1;
			break;
		case NEXTHDR_DEST:
			/* HAO MUST NOT appear more than once.
			 * XXX: It is better to try to find by the end of
			 * XXX: packet if HAO exists.
			 */
			if (ipv6_find_tlv(skb, offset, IPV6_TLV_HAO) >= 0) {
				net_dbg_ratelimited("mip6: hao exists already, override\n");
				return offset;
			}

			if (found_rhdr)
				return offset;

			break;
		default:
			return offset;
		}

		if (offset + sizeof(struct ipv6_opt_hdr) > packet_len)
			return -EINVAL;

		exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) +
						 offset);
		offset += ipv6_optlen(exthdr);
		if (offset > IPV6_MAXPLEN)
			return -EINVAL;
		*nexthdr = &exthdr->nexthdr;
	}

	return -EINVAL;
}
#endif

#if IS_ENABLED(CONFIG_IPV6)
static int xfrm6_hdr_offset(struct xfrm_state *x, struct sk_buff *skb, u8 **prevhdr)
{
	switch (x->type->proto) {
#if IS_ENABLED(CONFIG_IPV6_MIP6)
	case IPPROTO_DSTOPTS:
	case IPPROTO_ROUTING:
		return mip6_rthdr_offset(skb, prevhdr, x->type->proto);
#endif
	default:
		break;
	}

	return ip6_find_1stfragopt(skb, prevhdr);
}
#endif

/* Add encapsulation header.
 *
 * The IP header and mutable extension headers will be moved forward to make
 * space for the encapsulation header.
 */
static int xfrm6_transport_output(struct xfrm_state *x, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_IPV6)
	struct ipv6hdr *iph;
	u8 *prevhdr;
	int hdr_len;

	iph = ipv6_hdr(skb);
	skb_set_inner_transport_header(skb, skb_transport_offset(skb));

	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
	if (hdr_len < 0)
		return hdr_len;
	skb_set_mac_header(skb,
			   (prevhdr - x->props.header_len) - skb->data);
	skb_set_network_header(skb, -x->props.header_len);
	skb->transport_header = skb->network_header + hdr_len;
	__skb_pull(skb, hdr_len);
	memmove(ipv6_hdr(skb), iph, hdr_len);
	return 0;
#else
	WARN_ON_ONCE(1);
	return -EAFNOSUPPORT;
#endif
}

/* Add route optimization header space.
 *
 * The IP header and mutable extension headers will be moved forward to make
 * space for the route optimization header.
 */
static int xfrm6_ro_output(struct xfrm_state *x, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_IPV6)
	struct ipv6hdr *iph;
	u8 *prevhdr;
	int hdr_len;

	iph = ipv6_hdr(skb);

	hdr_len = xfrm6_hdr_offset(x, skb, &prevhdr);
	if (hdr_len < 0)
		return hdr_len;
	skb_set_mac_header(skb,
			   (prevhdr - x->props.header_len) - skb->data);
	skb_set_network_header(skb, -x->props.header_len);
	skb->transport_header = skb->network_header + hdr_len;
	__skb_pull(skb, hdr_len);
	memmove(ipv6_hdr(skb), iph, hdr_len);

	return 0;
#else
	WARN_ON_ONCE(1);
	return -EAFNOSUPPORT;
#endif
}

/* Add encapsulation header.
 *
 * The top IP header will be constructed per draft-nikander-esp-beet-mode-06.txt.
 */
static int xfrm4_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
{
	struct ip_beet_phdr *ph;
	struct iphdr *top_iph;
	int hdrlen, optlen;

	hdrlen = 0;
	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
	if (unlikely(optlen))
		hdrlen += IPV4_BEET_PHMAXLEN - (optlen & 4);

	skb_set_network_header(skb, -x->props.header_len - hdrlen +
			       (XFRM_MODE_SKB_CB(skb)->ihl - sizeof(*top_iph)));
	if (x->sel.family != AF_INET6)
		skb->network_header += IPV4_BEET_PHMAXLEN;
	skb->mac_header = skb->network_header +
			  offsetof(struct iphdr, protocol);
	skb->transport_header = skb->network_header + sizeof(*top_iph);

	xfrm4_beet_make_header(skb);

	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdrlen);

	top_iph = ip_hdr(skb);

	if (unlikely(optlen)) {
		if (WARN_ON(optlen < 0))
			return -EINVAL;

		ph->padlen = 4 - (optlen & 4);
		ph->hdrlen = optlen / 8;
		ph->nexthdr = top_iph->protocol;
		if (ph->padlen)
			memset(ph + 1, IPOPT_NOP, ph->padlen);

		top_iph->protocol = IPPROTO_BEETPH;
		top_iph->ihl = sizeof(struct iphdr) / 4;
	}

	top_iph->saddr = x->props.saddr.a4;
	top_iph->daddr = x->id.daddr.a4;

	return 0;
}

/* Add encapsulation header.
 *
 * The top IP header will be constructed per RFC 2401.
 */
static int xfrm4_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
{
	bool small_ipv6 = (skb->protocol == htons(ETH_P_IPV6)) && (skb->len <= IPV6_MIN_MTU);
	struct dst_entry *dst = skb_dst(skb);
	struct iphdr *top_iph;
	int flags;

	skb_set_inner_network_header(skb, skb_network_offset(skb));
	skb_set_inner_transport_header(skb, skb_transport_offset(skb));

	skb_set_network_header(skb, -x->props.header_len);
	skb->mac_header = skb->network_header +
			  offsetof(struct iphdr, protocol);
	skb->transport_header = skb->network_header + sizeof(*top_iph);
	top_iph = ip_hdr(skb);

	top_iph->ihl = 5;
	top_iph->version = 4;

	top_iph->protocol = xfrm_af2proto(skb_dst(skb)->ops->family);

	/* DS disclosing depends on XFRM_SA_XFLAG_DONT_ENCAP_DSCP */
	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
		top_iph->tos = 0;
	else
		top_iph->tos = XFRM_MODE_SKB_CB(skb)->tos;
	top_iph->tos = INET_ECN_encapsulate(top_iph->tos,
					    XFRM_MODE_SKB_CB(skb)->tos);

	flags = x->props.flags;
	if (flags & XFRM_STATE_NOECN)
		IP_ECN_clear(top_iph);

	top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) || small_ipv6 ?
		0 : (XFRM_MODE_SKB_CB(skb)->frag_off & htons(IP_DF));

	top_iph->ttl = ip4_dst_hoplimit(xfrm_dst_child(dst));

	top_iph->saddr = x->props.saddr.a4;
	top_iph->daddr = x->id.daddr.a4;
	ip_select_ident(dev_net(dst->dev), skb, NULL);

	return 0;
}

#if IS_ENABLED(CONFIG_IPV6)
static int xfrm6_tunnel_encap_add(struct xfrm_state *x, struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct ipv6hdr *top_iph;
	int dsfield;

	skb_set_inner_network_header(skb, skb_network_offset(skb));
	skb_set_inner_transport_header(skb, skb_transport_offset(skb));

	skb_set_network_header(skb, -x->props.header_len);
	skb->mac_header = skb->network_header +
			  offsetof(struct ipv6hdr, nexthdr);
	skb->transport_header = skb->network_header + sizeof(*top_iph);
	top_iph = ipv6_hdr(skb);

	top_iph->version = 6;

	memcpy(top_iph->flow_lbl, XFRM_MODE_SKB_CB(skb)->flow_lbl,
	       sizeof(top_iph->flow_lbl));
	top_iph->nexthdr = xfrm_af2proto(skb_dst(skb)->ops->family);

	if (x->props.extra_flags & XFRM_SA_XFLAG_DONT_ENCAP_DSCP)
		dsfield = 0;
	else
		dsfield = XFRM_MODE_SKB_CB(skb)->tos;
	dsfield = INET_ECN_encapsulate(dsfield, XFRM_MODE_SKB_CB(skb)->tos);
	if (x->props.flags & XFRM_STATE_NOECN)
		dsfield &= ~INET_ECN_MASK;
	ipv6_change_dsfield(top_iph, 0, dsfield);
	top_iph->hop_limit = ip6_dst_hoplimit(xfrm_dst_child(dst));
	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
	return 0;
}

static int xfrm6_beet_encap_add(struct xfrm_state *x, struct sk_buff *skb)
{
	struct ipv6hdr *top_iph;
	struct ip_beet_phdr *ph;
	int optlen, hdr_len;

	hdr_len = 0;
	optlen = XFRM_MODE_SKB_CB(skb)->optlen;
	if (unlikely(optlen))
		hdr_len += IPV4_BEET_PHMAXLEN - (optlen & 4);

	skb_set_network_header(skb, -x->props.header_len - hdr_len);
	if (x->sel.family != AF_INET6)
		skb->network_header += IPV4_BEET_PHMAXLEN;
	skb->mac_header = skb->network_header +
			  offsetof(struct ipv6hdr, nexthdr);
	skb->transport_header = skb->network_header + sizeof(*top_iph);
	ph = __skb_pull(skb, XFRM_MODE_SKB_CB(skb)->ihl - hdr_len);

	xfrm6_beet_make_header(skb);

	top_iph = ipv6_hdr(skb);
	if (unlikely(optlen)) {
		if (WARN_ON(optlen < 0))
			return -EINVAL;

		ph->padlen = 4 - (optlen & 4);
		ph->hdrlen = optlen / 8;
		ph->nexthdr = top_iph->nexthdr;
		if (ph->padlen)
			memset(ph + 1, IPOPT_NOP, ph->padlen);

		top_iph->nexthdr = IPPROTO_BEETPH;
	}

	top_iph->saddr = *(struct in6_addr *)&x->props.saddr;
	top_iph->daddr = *(struct in6_addr *)&x->id.daddr;
	return 0;
}
#endif

/* Add encapsulation header.
 *
 * On exit, the transport header will be set to the start of the
 * encapsulation header to be filled in by x->type->output and the mac
 * header will be set to the nextheader (protocol for IPv4) field of the
 * extension header directly preceding the encapsulation header, or in
 * its absence, that of the top IP header.
 * The value of the network header will always point to the top IP header
 * while skb->data will point to the payload.
 */
static int xfrm4_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;

	err = xfrm_inner_extract_output(x, skb);
	if (err)
		return err;

	IPCB(skb)->flags |= IPSKB_XFRM_TUNNEL_SIZE;
	skb->protocol = htons(ETH_P_IP);

	switch (x->props.mode) {
	case XFRM_MODE_BEET:
		return xfrm4_beet_encap_add(x, skb);
	case XFRM_MODE_TUNNEL:
		return xfrm4_tunnel_encap_add(x, skb);
	}

	WARN_ON_ONCE(1);
	return -EOPNOTSUPP;
}

static int xfrm6_prepare_output(struct xfrm_state *x, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_IPV6)
	int err;

	err = xfrm_inner_extract_output(x, skb);
	if (err)
		return err;

	skb->ignore_df = 1;
	skb->protocol = htons(ETH_P_IPV6);

	switch (x->props.mode) {
	case XFRM_MODE_BEET:
		return xfrm6_beet_encap_add(x, skb);
	case XFRM_MODE_TUNNEL:
		return xfrm6_tunnel_encap_add(x, skb);
	default:
		WARN_ON_ONCE(1);
		return -EOPNOTSUPP;
	}
#endif
	WARN_ON_ONCE(1);
	return -EAFNOSUPPORT;
}

static int xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
{
	switch (x->props.mode) {
	case XFRM_MODE_BEET:
	case XFRM_MODE_TUNNEL:
		if (x->props.family == AF_INET)
			return xfrm4_prepare_output(x, skb);
		if (x->props.family == AF_INET6)
			return xfrm6_prepare_output(x, skb);
		break;
	case XFRM_MODE_TRANSPORT:
		if (x->props.family == AF_INET)
			return xfrm4_transport_output(x, skb);
		if (x->props.family == AF_INET6)
			return xfrm6_transport_output(x, skb);
		break;
	case XFRM_MODE_ROUTEOPTIMIZATION:
		if (x->props.family == AF_INET6)
			return xfrm6_ro_output(x, skb);
		WARN_ON_ONCE(1);
		break;
	default:
		WARN_ON_ONCE(1);
		break;
	}

	return -EOPNOTSUPP;
}

#if IS_ENABLED(CONFIG_NET_PKTGEN)
int pktgen_xfrm_outer_mode_output(struct xfrm_state *x, struct sk_buff *skb)
{
	return xfrm_outer_mode_output(x, skb);
}
EXPORT_SYMBOL_GPL(pktgen_xfrm_outer_mode_output);
#endif

static int xfrm_output_one(struct sk_buff *skb, int err)
{
	struct dst_entry *dst = skb_dst(skb);
	struct xfrm_state *x = dst->xfrm;
	struct net *net = xs_net(x);

	if (err <= 0 || x->xso.type == XFRM_DEV_OFFLOAD_PACKET)
		goto resume;

	do {
		err = xfrm_skb_check_space(skb);
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			goto error_nolock;
		}

		skb->mark = xfrm_smark_get(skb->mark, x);

		err = xfrm_outer_mode_output(x, skb);
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
			goto error_nolock;
		}

		spin_lock_bh(&x->lock);

		if (unlikely(x->km.state != XFRM_STATE_VALID)) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEINVALID);
			err = -EINVAL;
			goto error;
		}

		err = xfrm_state_check_expire(x);
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEEXPIRED);
			goto error;
		}

		err = xfrm_replay_overflow(x, skb);
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
			goto error;
		}

		x->curlft.bytes += skb->len;
		x->curlft.packets++;
		x->lastused = ktime_get_real_seconds();

		spin_unlock_bh(&x->lock);

		skb_dst_force(skb);
		if (!skb_dst(skb)) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			err = -EHOSTUNREACH;
			goto error_nolock;
		}

		if (xfrm_offload(skb)) {
			x->type_offload->encap(x, skb);
		} else {
			/* Inner headers are invalid now. */
			skb->encapsulation = 0;

			err = x->type->output(x, skb);
			if (err == -EINPROGRESS)
				goto out;
		}

resume:
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEPROTOERROR);
			goto error_nolock;
		}

		dst = skb_dst_pop(skb);
		if (!dst) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			err = -EHOSTUNREACH;
			goto error_nolock;
		}
		skb_dst_set(skb, dst);
		x = dst->xfrm;
	} while (x && !(x->outer_mode.flags & XFRM_MODE_FLAG_TUNNEL));

	return 0;

error:
	spin_unlock_bh(&x->lock);
error_nolock:
	kfree_skb(skb);
out:
	return err;
}

int xfrm_output_resume(struct sock *sk, struct sk_buff *skb, int err)
{
	struct net *net = xs_net(skb_dst(skb)->xfrm);

	while (likely((err = xfrm_output_one(skb, err)) == 0)) {
		nf_reset_ct(skb);

		err = skb_dst(skb)->ops->local_out(net, sk, skb);
		if (unlikely(err != 1))
			goto out;

		if (!skb_dst(skb)->xfrm)
			return dst_output(net, sk, skb);

		err = nf_hook(skb_dst(skb)->ops->family,
			      NF_INET_POST_ROUTING, net, sk, skb,
			      NULL, skb_dst(skb)->dev, xfrm_output2);
		if (unlikely(err != 1))
			goto out;
	}

	if (err == -EINPROGRESS)
		err = 0;

out:
	return err;
}
EXPORT_SYMBOL_GPL(xfrm_output_resume);

static int xfrm_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	return xfrm_output_resume(sk, skb, 1);
}

static int xfrm_output_gso(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *segs, *nskb;

	BUILD_BUG_ON(sizeof(*IPCB(skb)) > SKB_GSO_CB_OFFSET);
	BUILD_BUG_ON(sizeof(*IP6CB(skb)) > SKB_GSO_CB_OFFSET);
	segs = skb_gso_segment(skb, 0);
	kfree_skb(skb);
	if (IS_ERR(segs))
		return PTR_ERR(segs);
	if (segs == NULL)
		return -EINVAL;

	skb_list_walk_safe(segs, segs, nskb) {
		int err;

		skb_mark_not_on_list(segs);
		err = xfrm_output2(net, sk, segs);

		if (unlikely(err)) {
			kfree_skb_list(nskb);
			return err;
		}
	}

	return 0;
}

/* For partial checksum offload, the outer header checksum is calculated
 * by software and the inner header checksum is calculated by hardware.
 * This requires hardware to know the inner packet type to calculate
 * the inner header checksum. Save inner ip protocol here to avoid
 * traversing the packet in the vendor's xmit code.
 * For IPsec tunnel mode save the ip protocol from the IP header of the
 * plain text packet. Otherwise If the encap type is IPIP, just save
 * skb->inner_ipproto in any other case get the ip protocol from the IP
 * header.
 */
static void xfrm_get_inner_ipproto(struct sk_buff *skb, struct xfrm_state *x)
{
	struct xfrm_offload *xo = xfrm_offload(skb);
	const struct ethhdr *eth;

	if (!xo)
		return;

	if (x->outer_mode.encap == XFRM_MODE_TUNNEL) {
		switch (x->outer_mode.family) {
		case AF_INET:
			xo->inner_ipproto = ip_hdr(skb)->protocol;
			break;
		case AF_INET6:
			xo->inner_ipproto = ipv6_hdr(skb)->nexthdr;
			break;
		default:
			break;
		}

		return;
	}

	/* non-Tunnel Mode */
	if (!skb->encapsulation)
		return;

	if (skb->inner_protocol_type == ENCAP_TYPE_IPPROTO) {
		xo->inner_ipproto = skb->inner_ipproto;
		return;
	}

	if (skb->inner_protocol_type != ENCAP_TYPE_ETHER)
		return;

	eth = (struct ethhdr *)skb_inner_mac_header(skb);

	switch (ntohs(eth->h_proto)) {
	case ETH_P_IPV6:
		xo->inner_ipproto = inner_ipv6_hdr(skb)->nexthdr;
		break;
	case ETH_P_IP:
		xo->inner_ipproto = inner_ip_hdr(skb)->protocol;
		break;
	}
}

int xfrm_output(struct sock *sk, struct sk_buff *skb)
{
	struct net *net = dev_net(skb_dst(skb)->dev);
	struct xfrm_state *x = skb_dst(skb)->xfrm;
	int family;
	int err;

	family = (x->xso.type != XFRM_DEV_OFFLOAD_PACKET) ? x->outer_mode.family
		: skb_dst(skb)->ops->family;

	switch (family) {
	case AF_INET:
		memset(IPCB(skb), 0, sizeof(*IPCB(skb)));
		IPCB(skb)->flags |= IPSKB_XFRM_TRANSFORMED;
		break;
	case AF_INET6:
		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));

		IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
		break;
	}

	if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET) {
		if (!xfrm_dev_offload_ok(skb, x)) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			kfree_skb(skb);
			return -EHOSTUNREACH;
		}

		return xfrm_output_resume(sk, skb, 0);
	}

	secpath_reset(skb);

	if (xfrm_dev_offload_ok(skb, x)) {
		struct sec_path *sp;

		sp = secpath_set(skb);
		if (!sp) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			kfree_skb(skb);
			return -ENOMEM;
		}

		sp->olen++;
		sp->xvec[sp->len++] = x;
		xfrm_state_hold(x);

		xfrm_get_inner_ipproto(skb, x);
		skb->encapsulation = 1;

		if (skb_is_gso(skb)) {
			if (skb->inner_protocol)
				return xfrm_output_gso(net, sk, skb);

			skb_shinfo(skb)->gso_type |= SKB_GSO_ESP;
			goto out;
		}

		if (x->xso.dev && x->xso.dev->features & NETIF_F_HW_ESP_TX_CSUM)
			goto out;
	} else {
		if (skb_is_gso(skb))
			return xfrm_output_gso(net, sk, skb);
	}

	if (skb->ip_summed == CHECKSUM_PARTIAL) {
		err = skb_checksum_help(skb);
		if (err) {
			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTERROR);
			kfree_skb(skb);
			return err;
		}
	}

out:
	return xfrm_output2(net, sk, skb);
}
EXPORT_SYMBOL_GPL(xfrm_output);

static int xfrm4_tunnel_check_size(struct sk_buff *skb)
{
	int mtu, ret = 0;

	if (IPCB(skb)->flags & IPSKB_XFRM_TUNNEL_SIZE)
		goto out;

	if (!(ip_hdr(skb)->frag_off & htons(IP_DF)) || skb->ignore_df)
		goto out;

	mtu = dst_mtu(skb_dst(skb));
	if ((!skb_is_gso(skb) && skb->len > mtu) ||
	    (skb_is_gso(skb) &&
	     !skb_gso_validate_network_len(skb, ip_skb_dst_mtu(skb->sk, skb)))) {
		skb->protocol = htons(ETH_P_IP);

		if (skb->sk)
			xfrm_local_error(skb, mtu);
		else
			icmp_send(skb, ICMP_DEST_UNREACH,
				  ICMP_FRAG_NEEDED, htonl(mtu));
		ret = -EMSGSIZE;
	}
out:
	return ret;
}

static int xfrm4_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
	int err;

	if (x->outer_mode.encap == XFRM_MODE_BEET &&
	    ip_is_fragment(ip_hdr(skb))) {
		net_warn_ratelimited("BEET mode doesn't support inner IPv4 fragments\n");
		return -EAFNOSUPPORT;
	}

	err = xfrm4_tunnel_check_size(skb);
	if (err)
		return err;

	XFRM_MODE_SKB_CB(skb)->protocol = ip_hdr(skb)->protocol;

	xfrm4_extract_header(skb);
	return 0;
}

#if IS_ENABLED(CONFIG_IPV6)
static int xfrm6_tunnel_check_size(struct sk_buff *skb)
{
	int mtu, ret = 0;
	struct dst_entry *dst = skb_dst(skb);

	if (skb->ignore_df)
		goto out;

	mtu = dst_mtu(dst);
	if (mtu < IPV6_MIN_MTU)
		mtu = IPV6_MIN_MTU;

	if ((!skb_is_gso(skb) && skb->len > mtu) ||
	    (skb_is_gso(skb) &&
	     !skb_gso_validate_network_len(skb, ip6_skb_dst_mtu(skb)))) {
		skb->dev = dst->dev;
		skb->protocol = htons(ETH_P_IPV6);

		if (xfrm6_local_dontfrag(skb->sk))
			ipv6_stub->xfrm6_local_rxpmtu(skb, mtu);
		else if (skb->sk)
			xfrm_local_error(skb, mtu);
		else
			icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
		ret = -EMSGSIZE;
	}
out:
	return ret;
}
#endif

static int xfrm6_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
#if IS_ENABLED(CONFIG_IPV6)
	int err;

	err = xfrm6_tunnel_check_size(skb);
	if (err)
		return err;

	XFRM_MODE_SKB_CB(skb)->protocol = ipv6_hdr(skb)->nexthdr;

	xfrm6_extract_header(skb);
	return 0;
#else
	WARN_ON_ONCE(1);
	return -EAFNOSUPPORT;
#endif
}

static int xfrm_inner_extract_output(struct xfrm_state *x, struct sk_buff *skb)
{
	switch (skb->protocol) {
	case htons(ETH_P_IP):
		return xfrm4_extract_output(x, skb);
	case htons(ETH_P_IPV6):
		return xfrm6_extract_output(x, skb);
	}

	return -EAFNOSUPPORT;
}

void xfrm_local_error(struct sk_buff *skb, int mtu)
{
	unsigned int proto;
	struct xfrm_state_afinfo *afinfo;

	if (skb->protocol == htons(ETH_P_IP))
		proto = AF_INET;
	else if (skb->protocol == htons(ETH_P_IPV6) &&
		 skb->sk->sk_family == AF_INET6)
		proto = AF_INET6;
	else
		return;

	afinfo = xfrm_state_get_afinfo(proto);
	if (afinfo) {
		afinfo->local_error(skb, mtu);
		rcu_read_unlock();
	}
}
EXPORT_SYMBOL_GPL(xfrm_local_error);