1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
4 *
5 * Development of this code funded by Astaro AG (http://www.astaro.com/)
6 */
7
8 #include <asm/unaligned.h>
9 #include <linux/kernel.h>
10 #include <linux/netlink.h>
11 #include <linux/netfilter.h>
12 #include <linux/netfilter/nf_tables.h>
13 #include <linux/sctp.h>
14 #include <net/netfilter/nf_tables_core.h>
15 #include <net/netfilter/nf_tables.h>
16 #include <net/sctp/sctp.h>
17 #include <net/tcp.h>
18
19 struct nft_exthdr {
20 u8 type;
21 u8 offset;
22 u8 len;
23 u8 op;
24 u8 dreg;
25 u8 sreg;
26 u8 flags;
27 };
28
optlen(const u8 * opt,unsigned int offset)29 static unsigned int optlen(const u8 *opt, unsigned int offset)
30 {
31 /* Beware zero-length options: make finite progress */
32 if (opt[offset] <= TCPOPT_NOP || opt[offset + 1] == 0)
33 return 1;
34 else
35 return opt[offset + 1];
36 }
37
nft_exthdr_ipv6_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)38 static void nft_exthdr_ipv6_eval(const struct nft_expr *expr,
39 struct nft_regs *regs,
40 const struct nft_pktinfo *pkt)
41 {
42 struct nft_exthdr *priv = nft_expr_priv(expr);
43 u32 *dest = ®s->data[priv->dreg];
44 unsigned int offset = 0;
45 int err;
46
47 if (pkt->skb->protocol != htons(ETH_P_IPV6))
48 goto err;
49
50 err = ipv6_find_hdr(pkt->skb, &offset, priv->type, NULL, NULL);
51 if (priv->flags & NFT_EXTHDR_F_PRESENT) {
52 nft_reg_store8(dest, err >= 0);
53 return;
54 } else if (err < 0) {
55 goto err;
56 }
57 offset += priv->offset;
58
59 dest[priv->len / NFT_REG32_SIZE] = 0;
60 if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
61 goto err;
62 return;
63 err:
64 regs->verdict.code = NFT_BREAK;
65 }
66
67 /* find the offset to specified option.
68 *
69 * If target header is found, its offset is set in *offset and return option
70 * number. Otherwise, return negative error.
71 *
72 * If the first fragment doesn't contain the End of Options it is considered
73 * invalid.
74 */
ipv4_find_option(struct net * net,struct sk_buff * skb,unsigned int * offset,int target)75 static int ipv4_find_option(struct net *net, struct sk_buff *skb,
76 unsigned int *offset, int target)
77 {
78 unsigned char optbuf[sizeof(struct ip_options) + 40];
79 struct ip_options *opt = (struct ip_options *)optbuf;
80 struct iphdr *iph, _iph;
81 unsigned int start;
82 bool found = false;
83 __be32 info;
84 int optlen;
85
86 iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
87 if (!iph)
88 return -EBADMSG;
89 start = sizeof(struct iphdr);
90
91 optlen = iph->ihl * 4 - (int)sizeof(struct iphdr);
92 if (optlen <= 0)
93 return -ENOENT;
94
95 memset(opt, 0, sizeof(struct ip_options));
96 /* Copy the options since __ip_options_compile() modifies
97 * the options.
98 */
99 if (skb_copy_bits(skb, start, opt->__data, optlen))
100 return -EBADMSG;
101 opt->optlen = optlen;
102
103 if (__ip_options_compile(net, opt, NULL, &info))
104 return -EBADMSG;
105
106 switch (target) {
107 case IPOPT_SSRR:
108 case IPOPT_LSRR:
109 if (!opt->srr)
110 break;
111 found = target == IPOPT_SSRR ? opt->is_strictroute :
112 !opt->is_strictroute;
113 if (found)
114 *offset = opt->srr + start;
115 break;
116 case IPOPT_RR:
117 if (!opt->rr)
118 break;
119 *offset = opt->rr + start;
120 found = true;
121 break;
122 case IPOPT_RA:
123 if (!opt->router_alert)
124 break;
125 *offset = opt->router_alert + start;
126 found = true;
127 break;
128 default:
129 return -EOPNOTSUPP;
130 }
131 return found ? target : -ENOENT;
132 }
133
nft_exthdr_ipv4_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)134 static void nft_exthdr_ipv4_eval(const struct nft_expr *expr,
135 struct nft_regs *regs,
136 const struct nft_pktinfo *pkt)
137 {
138 struct nft_exthdr *priv = nft_expr_priv(expr);
139 u32 *dest = ®s->data[priv->dreg];
140 struct sk_buff *skb = pkt->skb;
141 unsigned int offset;
142 int err;
143
144 if (skb->protocol != htons(ETH_P_IP))
145 goto err;
146
147 err = ipv4_find_option(nft_net(pkt), skb, &offset, priv->type);
148 if (priv->flags & NFT_EXTHDR_F_PRESENT) {
149 nft_reg_store8(dest, err >= 0);
150 return;
151 } else if (err < 0) {
152 goto err;
153 }
154 offset += priv->offset;
155
156 dest[priv->len / NFT_REG32_SIZE] = 0;
157 if (skb_copy_bits(pkt->skb, offset, dest, priv->len) < 0)
158 goto err;
159 return;
160 err:
161 regs->verdict.code = NFT_BREAK;
162 }
163
164 static void *
nft_tcp_header_pointer(const struct nft_pktinfo * pkt,unsigned int len,void * buffer,unsigned int * tcphdr_len)165 nft_tcp_header_pointer(const struct nft_pktinfo *pkt,
166 unsigned int len, void *buffer, unsigned int *tcphdr_len)
167 {
168 struct tcphdr *tcph;
169
170 if (pkt->tprot != IPPROTO_TCP)
171 return NULL;
172
173 tcph = skb_header_pointer(pkt->skb, nft_thoff(pkt), sizeof(*tcph), buffer);
174 if (!tcph)
175 return NULL;
176
177 *tcphdr_len = __tcp_hdrlen(tcph);
178 if (*tcphdr_len < sizeof(*tcph) || *tcphdr_len > len)
179 return NULL;
180
181 return skb_header_pointer(pkt->skb, nft_thoff(pkt), *tcphdr_len, buffer);
182 }
183
nft_exthdr_tcp_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)184 static void nft_exthdr_tcp_eval(const struct nft_expr *expr,
185 struct nft_regs *regs,
186 const struct nft_pktinfo *pkt)
187 {
188 u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
189 struct nft_exthdr *priv = nft_expr_priv(expr);
190 unsigned int i, optl, tcphdr_len, offset;
191 u32 *dest = ®s->data[priv->dreg];
192 struct tcphdr *tcph;
193 u8 *opt;
194
195 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
196 if (!tcph)
197 goto err;
198
199 opt = (u8 *)tcph;
200 for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
201 optl = optlen(opt, i);
202
203 if (priv->type != opt[i])
204 continue;
205
206 if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
207 goto err;
208
209 offset = i + priv->offset;
210 if (priv->flags & NFT_EXTHDR_F_PRESENT) {
211 *dest = 1;
212 } else {
213 dest[priv->len / NFT_REG32_SIZE] = 0;
214 memcpy(dest, opt + offset, priv->len);
215 }
216
217 return;
218 }
219
220 err:
221 if (priv->flags & NFT_EXTHDR_F_PRESENT)
222 *dest = 0;
223 else
224 regs->verdict.code = NFT_BREAK;
225 }
226
nft_exthdr_tcp_set_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)227 static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr,
228 struct nft_regs *regs,
229 const struct nft_pktinfo *pkt)
230 {
231 u8 buff[sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE];
232 struct nft_exthdr *priv = nft_expr_priv(expr);
233 unsigned int i, optl, tcphdr_len, offset;
234 struct tcphdr *tcph;
235 u8 *opt;
236
237 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);
238 if (!tcph)
239 return;
240
241 opt = (u8 *)tcph;
242 for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {
243 union {
244 __be16 v16;
245 __be32 v32;
246 } old, new;
247
248 optl = optlen(opt, i);
249
250 if (priv->type != opt[i])
251 continue;
252
253 if (i + optl > tcphdr_len || priv->len + priv->offset > optl)
254 return;
255
256 if (skb_ensure_writable(pkt->skb,
257 nft_thoff(pkt) + i + priv->len))
258 return;
259
260 tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff,
261 &tcphdr_len);
262 if (!tcph)
263 return;
264
265 offset = i + priv->offset;
266
267 switch (priv->len) {
268 case 2:
269 old.v16 = get_unaligned((u16 *)(opt + offset));
270 new.v16 = (__force __be16)nft_reg_load16(
271 ®s->data[priv->sreg]);
272
273 switch (priv->type) {
274 case TCPOPT_MSS:
275 /* increase can cause connection to stall */
276 if (ntohs(old.v16) <= ntohs(new.v16))
277 return;
278 break;
279 }
280
281 if (old.v16 == new.v16)
282 return;
283
284 put_unaligned(new.v16, (u16*)(opt + offset));
285 inet_proto_csum_replace2(&tcph->check, pkt->skb,
286 old.v16, new.v16, false);
287 break;
288 case 4:
289 new.v32 = regs->data[priv->sreg];
290 old.v32 = get_unaligned((u32 *)(opt + offset));
291
292 if (old.v32 == new.v32)
293 return;
294
295 put_unaligned(new.v32, (u32*)(opt + offset));
296 inet_proto_csum_replace4(&tcph->check, pkt->skb,
297 old.v32, new.v32, false);
298 break;
299 default:
300 WARN_ON_ONCE(1);
301 break;
302 }
303
304 return;
305 }
306 }
307
nft_exthdr_sctp_eval(const struct nft_expr * expr,struct nft_regs * regs,const struct nft_pktinfo * pkt)308 static void nft_exthdr_sctp_eval(const struct nft_expr *expr,
309 struct nft_regs *regs,
310 const struct nft_pktinfo *pkt)
311 {
312 unsigned int offset = nft_thoff(pkt) + sizeof(struct sctphdr);
313 struct nft_exthdr *priv = nft_expr_priv(expr);
314 u32 *dest = ®s->data[priv->dreg];
315 const struct sctp_chunkhdr *sch;
316 struct sctp_chunkhdr _sch;
317
318 if (pkt->tprot != IPPROTO_SCTP)
319 goto err;
320
321 do {
322 sch = skb_header_pointer(pkt->skb, offset, sizeof(_sch), &_sch);
323 if (!sch || !sch->length)
324 break;
325
326 if (sch->type == priv->type) {
327 if (priv->flags & NFT_EXTHDR_F_PRESENT) {
328 nft_reg_store8(dest, true);
329 return;
330 }
331 if (priv->offset + priv->len > ntohs(sch->length) ||
332 offset + ntohs(sch->length) > pkt->skb->len)
333 break;
334
335 dest[priv->len / NFT_REG32_SIZE] = 0;
336 if (skb_copy_bits(pkt->skb, offset + priv->offset,
337 dest, priv->len) < 0)
338 break;
339 return;
340 }
341 offset += SCTP_PAD4(ntohs(sch->length));
342 } while (offset < pkt->skb->len);
343 err:
344 if (priv->flags & NFT_EXTHDR_F_PRESENT)
345 nft_reg_store8(dest, false);
346 else
347 regs->verdict.code = NFT_BREAK;
348 }
349
350 static const struct nla_policy nft_exthdr_policy[NFTA_EXTHDR_MAX + 1] = {
351 [NFTA_EXTHDR_DREG] = { .type = NLA_U32 },
352 [NFTA_EXTHDR_TYPE] = { .type = NLA_U8 },
353 [NFTA_EXTHDR_OFFSET] = { .type = NLA_U32 },
354 [NFTA_EXTHDR_LEN] = { .type = NLA_U32 },
355 [NFTA_EXTHDR_FLAGS] = { .type = NLA_U32 },
356 [NFTA_EXTHDR_OP] = { .type = NLA_U32 },
357 [NFTA_EXTHDR_SREG] = { .type = NLA_U32 },
358 };
359
nft_exthdr_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])360 static int nft_exthdr_init(const struct nft_ctx *ctx,
361 const struct nft_expr *expr,
362 const struct nlattr * const tb[])
363 {
364 struct nft_exthdr *priv = nft_expr_priv(expr);
365 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
366 int err;
367
368 if (!tb[NFTA_EXTHDR_DREG] ||
369 !tb[NFTA_EXTHDR_TYPE] ||
370 !tb[NFTA_EXTHDR_OFFSET] ||
371 !tb[NFTA_EXTHDR_LEN])
372 return -EINVAL;
373
374 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
375 if (err < 0)
376 return err;
377
378 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
379 if (err < 0)
380 return err;
381
382 if (tb[NFTA_EXTHDR_FLAGS]) {
383 err = nft_parse_u32_check(tb[NFTA_EXTHDR_FLAGS], U8_MAX, &flags);
384 if (err < 0)
385 return err;
386
387 if (flags & ~NFT_EXTHDR_F_PRESENT)
388 return -EINVAL;
389 }
390
391 if (tb[NFTA_EXTHDR_OP]) {
392 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
393 if (err < 0)
394 return err;
395 }
396
397 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
398 priv->offset = offset;
399 priv->len = len;
400 priv->flags = flags;
401 priv->op = op;
402
403 return nft_parse_register_store(ctx, tb[NFTA_EXTHDR_DREG],
404 &priv->dreg, NULL, NFT_DATA_VALUE,
405 priv->len);
406 }
407
nft_exthdr_tcp_set_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])408 static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx,
409 const struct nft_expr *expr,
410 const struct nlattr * const tb[])
411 {
412 struct nft_exthdr *priv = nft_expr_priv(expr);
413 u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
414 int err;
415
416 if (!tb[NFTA_EXTHDR_SREG] ||
417 !tb[NFTA_EXTHDR_TYPE] ||
418 !tb[NFTA_EXTHDR_OFFSET] ||
419 !tb[NFTA_EXTHDR_LEN])
420 return -EINVAL;
421
422 if (tb[NFTA_EXTHDR_DREG] || tb[NFTA_EXTHDR_FLAGS])
423 return -EINVAL;
424
425 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OFFSET], U8_MAX, &offset);
426 if (err < 0)
427 return err;
428
429 err = nft_parse_u32_check(tb[NFTA_EXTHDR_LEN], U8_MAX, &len);
430 if (err < 0)
431 return err;
432
433 if (offset < 2)
434 return -EOPNOTSUPP;
435
436 switch (len) {
437 case 2: break;
438 case 4: break;
439 default:
440 return -EOPNOTSUPP;
441 }
442
443 err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
444 if (err < 0)
445 return err;
446
447 priv->type = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
448 priv->offset = offset;
449 priv->len = len;
450 priv->flags = flags;
451 priv->op = op;
452
453 return nft_parse_register_load(tb[NFTA_EXTHDR_SREG], &priv->sreg,
454 priv->len);
455 }
456
nft_exthdr_ipv4_init(const struct nft_ctx * ctx,const struct nft_expr * expr,const struct nlattr * const tb[])457 static int nft_exthdr_ipv4_init(const struct nft_ctx *ctx,
458 const struct nft_expr *expr,
459 const struct nlattr * const tb[])
460 {
461 struct nft_exthdr *priv = nft_expr_priv(expr);
462 int err = nft_exthdr_init(ctx, expr, tb);
463
464 if (err < 0)
465 return err;
466
467 switch (priv->type) {
468 case IPOPT_SSRR:
469 case IPOPT_LSRR:
470 case IPOPT_RR:
471 case IPOPT_RA:
472 break;
473 default:
474 return -EOPNOTSUPP;
475 }
476 return 0;
477 }
478
nft_exthdr_dump_common(struct sk_buff * skb,const struct nft_exthdr * priv)479 static int nft_exthdr_dump_common(struct sk_buff *skb, const struct nft_exthdr *priv)
480 {
481 if (nla_put_u8(skb, NFTA_EXTHDR_TYPE, priv->type))
482 goto nla_put_failure;
483 if (nla_put_be32(skb, NFTA_EXTHDR_OFFSET, htonl(priv->offset)))
484 goto nla_put_failure;
485 if (nla_put_be32(skb, NFTA_EXTHDR_LEN, htonl(priv->len)))
486 goto nla_put_failure;
487 if (nla_put_be32(skb, NFTA_EXTHDR_FLAGS, htonl(priv->flags)))
488 goto nla_put_failure;
489 if (nla_put_be32(skb, NFTA_EXTHDR_OP, htonl(priv->op)))
490 goto nla_put_failure;
491 return 0;
492
493 nla_put_failure:
494 return -1;
495 }
496
nft_exthdr_dump(struct sk_buff * skb,const struct nft_expr * expr)497 static int nft_exthdr_dump(struct sk_buff *skb, const struct nft_expr *expr)
498 {
499 const struct nft_exthdr *priv = nft_expr_priv(expr);
500
501 if (nft_dump_register(skb, NFTA_EXTHDR_DREG, priv->dreg))
502 return -1;
503
504 return nft_exthdr_dump_common(skb, priv);
505 }
506
nft_exthdr_dump_set(struct sk_buff * skb,const struct nft_expr * expr)507 static int nft_exthdr_dump_set(struct sk_buff *skb, const struct nft_expr *expr)
508 {
509 const struct nft_exthdr *priv = nft_expr_priv(expr);
510
511 if (nft_dump_register(skb, NFTA_EXTHDR_SREG, priv->sreg))
512 return -1;
513
514 return nft_exthdr_dump_common(skb, priv);
515 }
516
517 static const struct nft_expr_ops nft_exthdr_ipv6_ops = {
518 .type = &nft_exthdr_type,
519 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
520 .eval = nft_exthdr_ipv6_eval,
521 .init = nft_exthdr_init,
522 .dump = nft_exthdr_dump,
523 };
524
525 static const struct nft_expr_ops nft_exthdr_ipv4_ops = {
526 .type = &nft_exthdr_type,
527 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
528 .eval = nft_exthdr_ipv4_eval,
529 .init = nft_exthdr_ipv4_init,
530 .dump = nft_exthdr_dump,
531 };
532
533 static const struct nft_expr_ops nft_exthdr_tcp_ops = {
534 .type = &nft_exthdr_type,
535 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
536 .eval = nft_exthdr_tcp_eval,
537 .init = nft_exthdr_init,
538 .dump = nft_exthdr_dump,
539 };
540
541 static const struct nft_expr_ops nft_exthdr_tcp_set_ops = {
542 .type = &nft_exthdr_type,
543 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
544 .eval = nft_exthdr_tcp_set_eval,
545 .init = nft_exthdr_tcp_set_init,
546 .dump = nft_exthdr_dump_set,
547 };
548
549 static const struct nft_expr_ops nft_exthdr_sctp_ops = {
550 .type = &nft_exthdr_type,
551 .size = NFT_EXPR_SIZE(sizeof(struct nft_exthdr)),
552 .eval = nft_exthdr_sctp_eval,
553 .init = nft_exthdr_init,
554 .dump = nft_exthdr_dump,
555 };
556
557 static const struct nft_expr_ops *
nft_exthdr_select_ops(const struct nft_ctx * ctx,const struct nlattr * const tb[])558 nft_exthdr_select_ops(const struct nft_ctx *ctx,
559 const struct nlattr * const tb[])
560 {
561 u32 op;
562
563 if (!tb[NFTA_EXTHDR_OP])
564 return &nft_exthdr_ipv6_ops;
565
566 if (tb[NFTA_EXTHDR_SREG] && tb[NFTA_EXTHDR_DREG])
567 return ERR_PTR(-EOPNOTSUPP);
568
569 op = ntohl(nla_get_be32(tb[NFTA_EXTHDR_OP]));
570 switch (op) {
571 case NFT_EXTHDR_OP_TCPOPT:
572 if (tb[NFTA_EXTHDR_SREG])
573 return &nft_exthdr_tcp_set_ops;
574 if (tb[NFTA_EXTHDR_DREG])
575 return &nft_exthdr_tcp_ops;
576 break;
577 case NFT_EXTHDR_OP_IPV6:
578 if (tb[NFTA_EXTHDR_DREG])
579 return &nft_exthdr_ipv6_ops;
580 break;
581 case NFT_EXTHDR_OP_IPV4:
582 if (ctx->family != NFPROTO_IPV6) {
583 if (tb[NFTA_EXTHDR_DREG])
584 return &nft_exthdr_ipv4_ops;
585 }
586 break;
587 case NFT_EXTHDR_OP_SCTP:
588 if (tb[NFTA_EXTHDR_DREG])
589 return &nft_exthdr_sctp_ops;
590 break;
591 }
592
593 return ERR_PTR(-EOPNOTSUPP);
594 }
595
596 struct nft_expr_type nft_exthdr_type __read_mostly = {
597 .name = "exthdr",
598 .select_ops = nft_exthdr_select_ops,
599 .policy = nft_exthdr_policy,
600 .maxattr = NFTA_EXTHDR_MAX,
601 .owner = THIS_MODULE,
602 };
603
