summaryrefslogtreecommitdiffstats
path: root/net/netfilter/nft_exthdr.c
blob: 6eb571d0c3fdfcb4ac6cef4b313f039ecfe2517b (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#include <asm/unaligned.h>
#include <linux/kernel.h>
#include <linux/netlink.h>
#include <linux/netfilter.h>
#include <linux/netfilter/nf_tables.h>
#include <linux/dccp.h>
#include <linux/sctp.h>
#include <net/netfilter/nf_tables_core.h>
#include <net/netfilter/nf_tables.h>
#include <net/tcp.h>

struct nft_exthdr {
	u8			type;
	u8			offset;
	u8			len;
	u8			op;
	u8			dreg;
	u8			sreg;
	u8			flags;
};

static unsigned int optlen(const u8 *opt, unsigned int offset)
{
	/* Beware zero-length options: make finite progress */
	if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0)
		return 1;
	else
		return opt[offset + 1];
}

static int nft_skb_copy_to_reg(const struct sk_buff *skb, int offset, u32 *dest, unsigned int len)
{
	if (len % NFT_REG32_SIZE)
		dest[len / NFT_REG32_SIZE] = 0;

	return skb_copy_bits(skb, offset, dest, len);
}

static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 *dest = &regs->data[priv->dreg];
	unsigned int offset = 0;
	int err;

	if (pkt->skb->protocol != htons(ETH_P_IPV6))
		goto err;

	err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
	if (priv->flags & NFT_EXTHDR_F_PRESENT) {
		nft_reg_store8(dest, err >= 0);
		return;
	} else if (err < 0) {
		goto err;
	}
	offset += priv->offset;

	if (nft_skb_copy_to_reg(pkt->skb, offset, dest, priv->len) < 0)
		goto err;
	return;
err:
	regs->verdict.code = NFT_BREAK;
}

/* find the offset to specified option.
 *
 * If target header is found, its offset is set in *offset and return option
 * number. Otherwise, return negative error.
 *
 * If the first fragment doesn't contain the End of Options it is considered
 * invalid.
 */
static int ipv4_find_option(struct net *net, struct sk_buff *skb,
			    unsigned int *offset, int target)
{
	unsigned char optbuf[sizeof(struct ip_options) + 40];
	struct ip_options *opt = (struct ip_options *)optbuf;
	struct iphdr *iph, _iph;
	unsigned int start;
	bool found = false;
	__be32 info;
	int optlen;

	iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
	if (!iph)
		return -EBADMSG;
	start = sizeof(struct iphdr);

	optlen = iph->ihl * 4 - (int)sizeof(struct iphdr);
	if (optlen <= 0)
		return -ENOENT;

	memset(opt, 0, sizeof(struct ip_options));
	/* Copy the options since __ip_options_compile() modifies
	 * the options.
	 */
	if (skb_copy_bits(skb, start, opt->__data, optlen))
		return -EBADMSG;
	opt->optlen = optlen;

	if (__ip_options_compile(net, opt, NULL, &info))
		return -EBADMSG;

	switch (target) {
	case IPOPT_SSRR:
	case IPOPT_LSRR:
		if (!opt->srr)
			break;
		found = target == IPOPT_SSRR ? opt->is_strictroute :
					       !opt->is_strictroute;
		if (found)
			*offset = opt->srr + start;
		break;
	case IPOPT_RR:
		if (!opt->rr)
			break;
		*offset = opt->rr + start;
		found = true;
		break;
	case IPOPT_RA:
		if (!opt->router_alert)
			break;
		*offset = opt->router_alert + start;
		found = true;
		break;
	default:
		return -EOPNOTSUPP;
	}
	return found ? target : -ENOENT;
}

static void nft_exthdr_ipv4_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 *dest = &regs->data[priv->dreg];
	struct sk_buff *skb = pkt->skb;
	unsigned int offset;
	int err;

	if (skb->protocol != htons(ETH_P_IP))
		goto err;

	err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type);
	if (priv->flags & NFT_EXTHDR_F_PRESENT) {
		nft_reg_store8(dest, err >= 0);
		return;
	} else if (err < 0) {
		goto err;
	}
	offset += priv->offset;

	if (nft_skb_copy_to_reg(pkt->skb, offset, dest, priv->len) < 0)
		goto err;
	return;
err:
	regs->verdict.code = NFT_BREAK;
}

static void *
nft_tcp_header_pointer(const struct nft_pktinfo *pkt,
		       unsigned int len, void *buffer, unsigned int *tcphdr_len)
{
	struct tcphdr *tcph;

	if (pkt->tprot != IPPROTO_TCP || pkt->fragoff)
		return NULL;

	tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt), sizeof(*tcph), buffer);
	if (!tcph)
		return NULL;

	*tcphdr_len = __tcp_hdrlen(tcph);
	if (*tcphdr_len < sizeof(*tcph) || *tcphdr_len > len)
		return NULL;

	return skb_header_pointer(pkt->skb, nft_thoff(pkt), *tcphdr_len, buffer);
}

static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
				struct nft_regs *regs,
				const struct nft_pktinfo *pkt)
{
	u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
	struct nft_exthdr *priv = nft_expr_priv(expr);
	unsigned int i, optl, tcphdr_len, offset;
	u32 *dest = &regs->data[priv->dreg];
	struct tcphdr *tcph;
	u8 *opt;

	tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
	if (!tcph)
		goto err;

	opt = (u8 *)tcph;
	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
		optl = optlen(opt, i);

		if (priv->type != opt[i])
			continue;

		if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
			goto err;

		offset = i + priv->offset;
		if (priv->flags & NFT_EXTHDR_F_PRESENT) {
			nft_reg_store8(dest, 1);
		} else {
			if (priv->len % NFT_REG32_SIZE)
				dest[priv->len / NFT_REG32_SIZE] = 0;
			memcpy(dest, opt + offset, priv->len);
		}

		return;
	}

err:
	if (priv->flags & NFT_EXTHDR_F_PRESENT)
		*dest = 0;
	else
		regs->verdict.code = NFT_BREAK;
}

static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr,
				    struct nft_regs *regs,
				    const struct nft_pktinfo *pkt)
{
	u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
	struct nft_exthdr *priv = nft_expr_priv(expr);
	unsigned int i, optl, tcphdr_len, offset;
	struct tcphdr *tcph;
	u8 *opt;

	tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
	if (!tcph)
		goto err;

	if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))
		goto err;

	tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));
	opt = (u8 *)tcph;

	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
		union {
			__be16 v16;
			__be32 v32;
		} old, new;

		optl = optlen(opt, i);

		if (priv->type != opt[i])
			continue;

		if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
			goto err;

		offset = i + priv->offset;

		switch (priv->len) {
		case 2:
			old.v16 = (__force __be16)get_unaligned((u16 *)(opt + offset));
			new.v16 = (__force __be16)nft_reg_load16(
				&regs->data[priv->sreg]);

			switch (priv->type) {
			case TCPOPT_MSS:
				/* increase can cause connection to stall */
				if (ntohs(old.v16) <= ntohs(new.v16))
					return;
			break;
			}

			if (old.v16 == new.v16)
				return;

			put_unaligned(new.v16, (__be16*)(opt + offset));
			inet_proto_csum_replace2(&tcph->check, pkt->skb,
						 old.v16, new.v16, false);
			break;
		case 4:
			new.v32 = nft_reg_load_be32(&regs->data[priv->sreg]);
			old.v32 = (__force __be32)get_unaligned((u32 *)(opt + offset));

			if (old.v32 == new.v32)
				return;

			put_unaligned(new.v32, (__be32*)(opt + offset));
			inet_proto_csum_replace4(&tcph->check, pkt->skb,
						 old.v32, new.v32, false);
			break;
		default:
			WARN_ON_ONCE(1);
			break;
		}

		return;
	}
	return;
err:
	regs->verdict.code = NFT_BREAK;
}

static void nft_exthdr_tcp_strip_eval(const struct nft_expr *expr,
				      struct nft_regs *regs,
				      const struct nft_pktinfo *pkt)
{
	u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
	struct nft_exthdr *priv = nft_expr_priv(expr);
	unsigned int i, tcphdr_len, optl;
	struct tcphdr *tcph;
	u8 *opt;

	tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
	if (!tcph)
		goto err;

	if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))
		goto drop;

	tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));
	opt = (u8 *)tcph;

	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
		unsigned int j;

		optl = optlen(opt, i);
		if (priv->type != opt[i])
			continue;

		if (i + optl > tcphdr_len)
			goto drop;

		for (j = 0; j < optl; ++j) {
			u16 n = TCPOPT_NOP;
			u16 o = opt[i+j];

			if ((i + j) % 2 == 0) {
				o <<= 8;
				n <<= 8;
			}
			inet_proto_csum_replace2(&tcph->check, pkt->skb, htons(o),
						 htons(n), false);
		}
		memset(opt + i, TCPOPT_NOP, optl);
		return;
	}

	/* option not found, continue. This allows to do multiple
	 * option removals per rule.
	 */
	return;
err:
	regs->verdict.code = NFT_BREAK;
	return;
drop:
	/* can't remove, no choice but to drop */
	regs->verdict.code = NF_DROP;
}

static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	unsigned int offset = nft_thoff(pkt) + sizeof(struct sctphdr);
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 *dest = &regs->data[priv->dreg];
	const struct sctp_chunkhdr *sch;
	struct sctp_chunkhdr _sch;

	if (pkt->tprot != IPPROTO_SCTP)
		goto err;

	do {
		sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch);
		if (!sch || !sch->length)
			break;

		if (sch->type == priv->type) {
			if (priv->flags & NFT_EXTHDR_F_PRESENT) {
				nft_reg_store8(dest, true);
				return;
			}
			if (priv->offset + priv->len > ntohs(sch->length) ||
			    offset + ntohs(sch->length) > pkt->skb->len)
				break;

			if (nft_skb_copy_to_reg(pkt->skb, offset + priv->offset,
						dest, priv->len) < 0)
				break;
			return;
		}
		offset += SCTP_PAD4(ntohs(sch->length));
	} while (offset < pkt->skb->len);
err:
	if (priv->flags & NFT_EXTHDR_F_PRESENT)
		nft_reg_store8(dest, false);
	else
		regs->verdict.code = NFT_BREAK;
}

static void nft_exthdr_dccp_eval(const struct nft_expr *expr,
				 struct nft_regs *regs,
				 const struct nft_pktinfo *pkt)
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	unsigned int thoff, dataoff, optoff, optlen, i;
	u32 *dest = &regs->data[priv->dreg];
	const struct dccp_hdr *dh;
	struct dccp_hdr _dh;

	if (pkt->tprot != IPPROTO_DCCP || pkt->fragoff)
		goto err;

	thoff = nft_thoff(pkt);

	dh = skb_header_pointer(pkt->skb, thoff, sizeof(_dh), &_dh);
	if (!dh)
		goto err;

	dataoff = dh->dccph_doff * sizeof(u32);
	optoff = __dccp_hdr_len(dh);
	if (dataoff <= optoff)
		goto err;

	optlen = dataoff - optoff;

	for (i = 0; i < optlen; ) {
		/* Options 0 (DCCPO_PADDING) - 31 (DCCPO_MAX_RESERVED) are 1B in
		 * the length; the remaining options are at least 2B long.  In
		 * all cases, the first byte contains the option type.  In
		 * multi-byte options, the second byte contains the option
		 * length, which must be at least two: 1 for the type plus 1 for
		 * the length plus 0-253 for any following option data.  We
		 * aren't interested in the option data, only the type and the
		 * length, so we don't need to read more than two bytes at a
		 * time.
		 */
		unsigned int buflen = optlen - i;
		u8 buf[2], *bufp;
		u8 type, len;

		if (buflen > sizeof(buf))
			buflen = sizeof(buf);

		bufp = skb_header_pointer(pkt->skb, thoff + optoff + i, buflen,
					  &buf);
		if (!bufp)
			goto err;

		type = bufp[0];

		if (type == priv->type) {
			nft_reg_store8(dest, 1);
			return;
		}

		if (type <= DCCPO_MAX_RESERVED) {
			i++;
			continue;
		}

		if (buflen < 2)
			goto err;

		len = bufp[1];

		if (len < 2)
			goto err;

		i += len;
	}

err:
	*dest = 0;
}

static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
	[NFTA_EXTHDR_DREG]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_TYPE]		= { .type = NLA_U8 },
	[NFTA_EXTHDR_OFFSET]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_LEN]		= NLA_POLICY_MAX(NLA_BE32, 255),
	[NFTA_EXTHDR_FLAGS]		= { .type = NLA_U32 },
	[NFTA_EXTHDR_OP]		= NLA_POLICY_MAX(NLA_BE32, 255),
	[NFTA_EXTHDR_SREG]		= { .type = NLA_U32 },
};

static int nft_exthdr_init(const struct nft_ctx *ctx,
			   const struct nft_expr *expr,
			   const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
	int err;

	if (!tb[NFTA_EXTHDR_DREG] ||
	    !tb[NFTA_EXTHDR_TYPE] ||
	    !tb[NFTA_EXTHDR_OFFSET] ||
	    !tb[NFTA_EXTHDR_LEN])
		return -EINVAL;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
	if (err < 0)
		return err;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
	if (err < 0)
		return err;

	if (tb[NFTA_EXTHDR_FLAGS]) {
		err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
		if (err < 0)
			return err;

		if (flags & ~NFT_EXTHDR_F_PRESENT)
			return -EINVAL;
	}

	if (tb[NFTA_EXTHDR_OP]) {
		err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
		if (err < 0)
			return err;
	}

	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
	priv->offset = offset;
	priv->len    = len;
	priv->flags  = flags;
	priv->op     = op;

	return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG],
					&priv->dreg, NULL, NFT_DATA_VALUE,
					priv->len);
}

static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx,
				   const struct nft_expr *expr,
				   const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
	int err;

	if (!tb[NFTA_EXTHDR_SREG] ||
	    !tb[NFTA_EXTHDR_TYPE] ||
	    !tb[NFTA_EXTHDR_OFFSET] ||
	    !tb[NFTA_EXTHDR_LEN])
		return -EINVAL;

	if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS])
		return -EINVAL;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
	if (err < 0)
		return err;

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
	if (err < 0)
		return err;

	if (offset < 2)
		return -EOPNOTSUPP;

	switch (len) {
	case 2: break;
	case 4: break;
	default:
		return -EOPNOTSUPP;
	}

	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
	if (err < 0)
		return err;

	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
	priv->offset = offset;
	priv->len    = len;
	priv->flags  = flags;
	priv->op     = op;

	return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg,
				       priv->len);
}

static int nft_exthdr_tcp_strip_init(const struct nft_ctx *ctx,
				     const struct nft_expr *expr,
				     const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);

	if (tb[NFTA_EXTHDR_SREG] ||
	    tb[NFTA_EXTHDR_DREG] ||
	    tb[NFTA_EXTHDR_FLAGS] ||
	    tb[NFTA_EXTHDR_OFFSET] ||
	    tb[NFTA_EXTHDR_LEN])
		return -EINVAL;

	if (!tb[NFTA_EXTHDR_TYPE])
		return -EINVAL;

	priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
	priv->op = NFT_EXTHDR_OP_TCPOPT;

	return 0;
}

static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx,
				const struct nft_expr *expr,
				const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	int err = nft_exthdr_init(ctx, expr, tb);

	if (err < 0)
		return err;

	switch (priv->type) {
	case IPOPT_SSRR:
	case IPOPT_LSRR:
	case IPOPT_RR:
	case IPOPT_RA:
		break;
	default:
		return -EOPNOTSUPP;
	}
	return 0;
}

static int nft_exthdr_dccp_init(const struct nft_ctx *ctx,
				const struct nft_expr *expr,
				const struct nlattr * const tb[])
{
	struct nft_exthdr *priv = nft_expr_priv(expr);
	int err = nft_exthdr_init(ctx, expr, tb);

	if (err < 0)
		return err;

	if (!(priv->flags & NFT_EXTHDR_F_PRESENT))
		return -EOPNOTSUPP;

	return 0;
}

static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv)
{
	if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
		goto nla_put_failure;
	return 0;

nla_put_failure:
	return -1;
}

static int nft_exthdr_dump(struct sk_buff *skb,
			   const struct nft_expr *expr, bool reset)
{
	const struct nft_exthdr *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
		return -1;

	return nft_exthdr_dump_common(skb, priv);
}

static int nft_exthdr_dump_set(struct sk_buff *skb,
			       const struct nft_expr *expr, bool reset)
{
	const struct nft_exthdr *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg))
		return -1;

	return nft_exthdr_dump_common(skb, priv);
}

static int nft_exthdr_dump_strip(struct sk_buff *skb,
				 const struct nft_expr *expr, bool reset)
{
	const struct nft_exthdr *priv = nft_expr_priv(expr);

	return nft_exthdr_dump_common(skb, priv);
}

static bool nft_exthdr_reduce(struct nft_regs_track *track,
			       const struct nft_expr *expr)
{
	const struct nft_exthdr *priv = nft_expr_priv(expr);
	const struct nft_exthdr *exthdr;

	if (!nft_reg_track_cmp(track, expr, priv->dreg)) {
		nft_reg_track_update(track, expr, priv->dreg, priv->len);
		return false;
	}

	exthdr = nft_expr_priv(track->regs[priv->dreg].selector);
	if (priv->type != exthdr->type ||
	    priv->op != exthdr->op ||
	    priv->flags != exthdr->flags ||
	    priv->offset != exthdr->offset ||
	    priv->len != exthdr->len) {
		nft_reg_track_update(track, expr, priv->dreg, priv->len);
		return false;
	}

	if (!track->regs[priv->dreg].bitwise)
		return true;

	return nft_expr_reduce_bitwise(track, expr);
}

static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_ipv6_eval,
	.init		= nft_exthdr_init,
	.dump		= nft_exthdr_dump,
	.reduce		= nft_exthdr_reduce,
};

static const struct nft_expr_ops nft_exthdr_ipv4_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_ipv4_eval,
	.init		= nft_exthdr_ipv4_init,
	.dump		= nft_exthdr_dump,
	.reduce		= nft_exthdr_reduce,
};

static const struct nft_expr_ops nft_exthdr_tcp_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_tcp_eval,
	.init		= nft_exthdr_init,
	.dump		= nft_exthdr_dump,
	.reduce		= nft_exthdr_reduce,
};

static const struct nft_expr_ops nft_exthdr_tcp_set_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_tcp_set_eval,
	.init		= nft_exthdr_tcp_set_init,
	.dump		= nft_exthdr_dump_set,
	.reduce		= NFT_REDUCE_READONLY,
};

static const struct nft_expr_ops nft_exthdr_tcp_strip_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_tcp_strip_eval,
	.init		= nft_exthdr_tcp_strip_init,
	.dump		= nft_exthdr_dump_strip,
	.reduce		= NFT_REDUCE_READONLY,
};

static const struct nft_expr_ops nft_exthdr_sctp_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_sctp_eval,
	.init		= nft_exthdr_init,
	.dump		= nft_exthdr_dump,
	.reduce		= nft_exthdr_reduce,
};

static const struct nft_expr_ops nft_exthdr_dccp_ops = {
	.type		= &nft_exthdr_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
	.eval		= nft_exthdr_dccp_eval,
	.init		= nft_exthdr_dccp_init,
	.dump		= nft_exthdr_dump,
	.reduce		= nft_exthdr_reduce,
};

static const struct nft_expr_ops *
nft_exthdr_select_ops(const struct nft_ctx *ctx,
		      const struct nlattr * const tb[])
{
	u32 op;

	if (!tb[NFTA_EXTHDR_OP])
		return &nft_exthdr_ipv6_ops;

	if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG])
		return ERR_PTR(-EOPNOTSUPP);

	op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP]));
	switch (op) {
	case NFT_EXTHDR_OP_TCPOPT:
		if (tb[NFTA_EXTHDR_SREG])
			return &nft_exthdr_tcp_set_ops;
		if (tb[NFTA_EXTHDR_DREG])
			return &nft_exthdr_tcp_ops;
		return &nft_exthdr_tcp_strip_ops;
	case NFT_EXTHDR_OP_IPV6:
		if (tb[NFTA_EXTHDR_DREG])
			return &nft_exthdr_ipv6_ops;
		break;
	case NFT_EXTHDR_OP_IPV4:
		if (ctx->family != NFPROTO_IPV6) {
			if (tb[NFTA_EXTHDR_DREG])
				return &nft_exthdr_ipv4_ops;
		}
		break;
	case NFT_EXTHDR_OP_SCTP:
		if (tb[NFTA_EXTHDR_DREG])
			return &nft_exthdr_sctp_ops;
		break;
	case NFT_EXTHDR_OP_DCCP:
		if (tb[NFTA_EXTHDR_DREG])
			return &nft_exthdr_dccp_ops;
		break;
	}

	return ERR_PTR(-EOPNOTSUPP);
}

struct nft_expr_type nft_exthdr_type __read_mostly = {
	.name		= "exthdr",
	.select_ops	= nft_exthdr_select_ops,
	.policy		= nft_exthdr_policy,
	.maxattr	= NFTA_EXTHDR_MAX,
	.owner		= THIS_MODULE,
};