1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Extension Header handling for IPv6
4 * Linux INET6 implementation
5 *
6 * Authors:
7 * Pedro Roque <roque@di.fc.ul.pt>
8 * Andi Kleen <ak@muc.de>
9 * Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
10 */
11
12 /* Changes:
13 * yoshfuji : ensure not to overrun while parsing
14 * tlv options.
15 * Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
16 * YOSHIFUJI Hideaki @USAGI Register inbound extension header
17 * handlers as inet6_protocol{}.
18 */
19
20 #include <linux/errno.h>
21 #include <linux/types.h>
22 #include <linux/socket.h>
23 #include <linux/sockios.h>
24 #include <linux/net.h>
25 #include <linux/netdevice.h>
26 #include <linux/in6.h>
27 #include <linux/icmpv6.h>
28 #include <linux/slab.h>
29 #include <linux/export.h>
30
31 #include <net/dst.h>
32 #include <net/sock.h>
33 #include <net/snmp.h>
34
35 #include <net/ipv6.h>
36 #include <net/protocol.h>
37 #include <net/transp_v6.h>
38 #include <net/rawv6.h>
39 #include <net/ndisc.h>
40 #include <net/ip6_route.h>
41 #include <net/addrconf.h>
42 #include <net/calipso.h>
43 #if IS_ENABLED(CONFIG_IPV6_MIP6)
44 #include <net/xfrm.h>
45 #endif
46 #include <linux/seg6.h>
47 #include <net/seg6.h>
48 #ifdef CONFIG_IPV6_SEG6_HMAC
49 #include <net/seg6_hmac.h>
50 #endif
51
52 #include <linux/uaccess.h>
53
54 /*
55 * Parsing tlv encoded headers.
56 *
57 * Parsing function "func" returns true, if parsing succeed
58 * and false, if it failed.
59 * It MUST NOT touch skb->h.
60 */
61
62 struct tlvtype_proc {
63 int type;
64 bool (*func)(struct sk_buff *skb, int offset);
65 };
66
67 /*********************
68 Generic functions
69 *********************/
70
71 /* An unknown option is detected, decide what to do */
72
ip6_tlvopt_unknown(struct sk_buff * skb,int optoff,bool disallow_unknowns)73 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
74 bool disallow_unknowns)
75 {
76 if (disallow_unknowns) {
77 /* If unknown TLVs are disallowed by configuration
78 * then always silently drop packet. Note this also
79 * means no ICMP parameter problem is sent which
80 * could be a good property to mitigate a reflection DOS
81 * attack.
82 */
83
84 goto drop;
85 }
86
87 switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
88 case 0: /* ignore */
89 return true;
90
91 case 1: /* drop packet */
92 break;
93
94 case 3: /* Send ICMP if not a multicast address and drop packet */
95 /* Actually, it is redundant check. icmp_send
96 will recheck in any case.
97 */
98 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
99 break;
100 /* fall through */
101 case 2: /* send ICMP PARM PROB regardless and drop packet */
102 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
103 return false;
104 }
105
106 drop:
107 kfree_skb(skb);
108 return false;
109 }
110
111 /* Parse tlv encoded option header (hop-by-hop or destination) */
112
ip6_parse_tlv(const struct tlvtype_proc * procs,struct sk_buff * skb,int max_count)113 static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
114 struct sk_buff *skb,
115 int max_count)
116 {
117 int len = (skb_transport_header(skb)[1] + 1) << 3;
118 const unsigned char *nh = skb_network_header(skb);
119 int off = skb_network_header_len(skb);
120 const struct tlvtype_proc *curr;
121 bool disallow_unknowns = false;
122 int tlv_count = 0;
123 int padlen = 0;
124
125 if (unlikely(max_count < 0)) {
126 disallow_unknowns = true;
127 max_count = -max_count;
128 }
129
130 if (skb_transport_offset(skb) + len > skb_headlen(skb))
131 goto bad;
132
133 off += 2;
134 len -= 2;
135
136 while (len > 0) {
137 int optlen = nh[off + 1] + 2;
138 int i;
139
140 switch (nh[off]) {
141 case IPV6_TLV_PAD1:
142 optlen = 1;
143 padlen++;
144 if (padlen > 7)
145 goto bad;
146 break;
147
148 case IPV6_TLV_PADN:
149 /* RFC 2460 states that the purpose of PadN is
150 * to align the containing header to multiples
151 * of 8. 7 is therefore the highest valid value.
152 * See also RFC 4942, Section 2.1.9.5.
153 */
154 padlen += optlen;
155 if (padlen > 7)
156 goto bad;
157 /* RFC 4942 recommends receiving hosts to
158 * actively check PadN payload to contain
159 * only zeroes.
160 */
161 for (i = 2; i < optlen; i++) {
162 if (nh[off + i] != 0)
163 goto bad;
164 }
165 break;
166
167 default: /* Other TLV code so scan list */
168 if (optlen > len)
169 goto bad;
170
171 tlv_count++;
172 if (tlv_count > max_count)
173 goto bad;
174
175 for (curr = procs; curr->type >= 0; curr++) {
176 if (curr->type == nh[off]) {
177 /* type specific length/alignment
178 checks will be performed in the
179 func(). */
180 if (curr->func(skb, off) == false)
181 return false;
182 break;
183 }
184 }
185 if (curr->type < 0 &&
186 !ip6_tlvopt_unknown(skb, off, disallow_unknowns))
187 return false;
188
189 padlen = 0;
190 break;
191 }
192 off += optlen;
193 len -= optlen;
194 }
195
196 if (len == 0)
197 return true;
198 bad:
199 kfree_skb(skb);
200 return false;
201 }
202
203 /*****************************
204 Destination options header.
205 *****************************/
206
207 #if IS_ENABLED(CONFIG_IPV6_MIP6)
ipv6_dest_hao(struct sk_buff * skb,int optoff)208 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
209 {
210 struct ipv6_destopt_hao *hao;
211 struct inet6_skb_parm *opt = IP6CB(skb);
212 struct ipv6hdr *ipv6h = ipv6_hdr(skb);
213 int ret;
214
215 if (opt->dsthao) {
216 net_dbg_ratelimited("hao duplicated\n");
217 goto discard;
218 }
219 opt->dsthao = opt->dst1;
220 opt->dst1 = 0;
221
222 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
223
224 if (hao->length != 16) {
225 net_dbg_ratelimited("hao invalid option length = %d\n",
226 hao->length);
227 goto discard;
228 }
229
230 if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
231 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
232 &hao->addr);
233 goto discard;
234 }
235
236 ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
237 (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
238 if (unlikely(ret < 0))
239 goto discard;
240
241 if (skb_cloned(skb)) {
242 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
243 goto discard;
244
245 /* update all variable using below by copied skbuff */
246 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
247 optoff);
248 ipv6h = ipv6_hdr(skb);
249 }
250
251 if (skb->ip_summed == CHECKSUM_COMPLETE)
252 skb->ip_summed = CHECKSUM_NONE;
253
254 swap(ipv6h->saddr, hao->addr);
255
256 if (skb->tstamp == 0)
257 __net_timestamp(skb);
258
259 return true;
260
261 discard:
262 kfree_skb(skb);
263 return false;
264 }
265 #endif
266
267 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
268 #if IS_ENABLED(CONFIG_IPV6_MIP6)
269 {
270 .type = IPV6_TLV_HAO,
271 .func = ipv6_dest_hao,
272 },
273 #endif
274 {-1, NULL}
275 };
276
ipv6_destopt_rcv(struct sk_buff * skb)277 static int ipv6_destopt_rcv(struct sk_buff *skb)
278 {
279 struct inet6_dev *idev = __in6_dev_get(skb->dev);
280 struct inet6_skb_parm *opt = IP6CB(skb);
281 #if IS_ENABLED(CONFIG_IPV6_MIP6)
282 __u16 dstbuf;
283 #endif
284 struct dst_entry *dst = skb_dst(skb);
285 struct net *net = dev_net(skb->dev);
286 int extlen;
287
288 if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
289 !pskb_may_pull(skb, (skb_transport_offset(skb) +
290 ((skb_transport_header(skb)[1] + 1) << 3)))) {
291 __IP6_INC_STATS(dev_net(dst->dev), idev,
292 IPSTATS_MIB_INHDRERRORS);
293 fail_and_free:
294 kfree_skb(skb);
295 return -1;
296 }
297
298 extlen = (skb_transport_header(skb)[1] + 1) << 3;
299 if (extlen > net->ipv6.sysctl.max_dst_opts_len)
300 goto fail_and_free;
301
302 opt->lastopt = opt->dst1 = skb_network_header_len(skb);
303 #if IS_ENABLED(CONFIG_IPV6_MIP6)
304 dstbuf = opt->dst1;
305 #endif
306
307 if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
308 init_net.ipv6.sysctl.max_dst_opts_cnt)) {
309 skb->transport_header += extlen;
310 opt = IP6CB(skb);
311 #if IS_ENABLED(CONFIG_IPV6_MIP6)
312 opt->nhoff = dstbuf;
313 #else
314 opt->nhoff = opt->dst1;
315 #endif
316 return 1;
317 }
318
319 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
320 return -1;
321 }
322
seg6_update_csum(struct sk_buff * skb)323 static void seg6_update_csum(struct sk_buff *skb)
324 {
325 struct ipv6_sr_hdr *hdr;
326 struct in6_addr *addr;
327 __be32 from, to;
328
329 /* srh is at transport offset and seg_left is already decremented
330 * but daddr is not yet updated with next segment
331 */
332
333 hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
334 addr = hdr->segments + hdr->segments_left;
335
336 hdr->segments_left++;
337 from = *(__be32 *)hdr;
338
339 hdr->segments_left--;
340 to = *(__be32 *)hdr;
341
342 /* update skb csum with diff resulting from seg_left decrement */
343
344 update_csum_diff4(skb, from, to);
345
346 /* compute csum diff between current and next segment and update */
347
348 update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
349 (__be32 *)addr);
350 }
351
ipv6_srh_rcv(struct sk_buff * skb)352 static int ipv6_srh_rcv(struct sk_buff *skb)
353 {
354 struct inet6_skb_parm *opt = IP6CB(skb);
355 struct net *net = dev_net(skb->dev);
356 struct ipv6_sr_hdr *hdr;
357 struct inet6_dev *idev;
358 struct in6_addr *addr;
359 int accept_seg6;
360
361 hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
362
363 idev = __in6_dev_get(skb->dev);
364
365 accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
366 if (accept_seg6 > idev->cnf.seg6_enabled)
367 accept_seg6 = idev->cnf.seg6_enabled;
368
369 if (!accept_seg6) {
370 kfree_skb(skb);
371 return -1;
372 }
373
374 #ifdef CONFIG_IPV6_SEG6_HMAC
375 if (!seg6_hmac_validate_skb(skb)) {
376 kfree_skb(skb);
377 return -1;
378 }
379 #endif
380
381 looped_back:
382 if (hdr->segments_left == 0) {
383 if (hdr->nexthdr == NEXTHDR_IPV6) {
384 int offset = (hdr->hdrlen + 1) << 3;
385
386 skb_postpull_rcsum(skb, skb_network_header(skb),
387 skb_network_header_len(skb));
388
389 if (!pskb_pull(skb, offset)) {
390 kfree_skb(skb);
391 return -1;
392 }
393 skb_postpull_rcsum(skb, skb_transport_header(skb),
394 offset);
395
396 skb_reset_network_header(skb);
397 skb_reset_transport_header(skb);
398 skb->encapsulation = 0;
399
400 __skb_tunnel_rx(skb, skb->dev, net);
401
402 netif_rx(skb);
403 return -1;
404 }
405
406 opt->srcrt = skb_network_header_len(skb);
407 opt->lastopt = opt->srcrt;
408 skb->transport_header += (hdr->hdrlen + 1) << 3;
409 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
410
411 return 1;
412 }
413
414 if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
415 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
416 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
417 ((&hdr->segments_left) -
418 skb_network_header(skb)));
419 return -1;
420 }
421
422 if (skb_cloned(skb)) {
423 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
424 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
425 IPSTATS_MIB_OUTDISCARDS);
426 kfree_skb(skb);
427 return -1;
428 }
429 }
430
431 hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
432
433 hdr->segments_left--;
434 addr = hdr->segments + hdr->segments_left;
435
436 skb_push(skb, sizeof(struct ipv6hdr));
437
438 if (skb->ip_summed == CHECKSUM_COMPLETE)
439 seg6_update_csum(skb);
440
441 ipv6_hdr(skb)->daddr = *addr;
442
443 skb_dst_drop(skb);
444
445 ip6_route_input(skb);
446
447 if (skb_dst(skb)->error) {
448 dst_input(skb);
449 return -1;
450 }
451
452 if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
453 if (ipv6_hdr(skb)->hop_limit <= 1) {
454 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
455 icmpv6_send(skb, ICMPV6_TIME_EXCEED,
456 ICMPV6_EXC_HOPLIMIT, 0);
457 kfree_skb(skb);
458 return -1;
459 }
460 ipv6_hdr(skb)->hop_limit--;
461
462 skb_pull(skb, sizeof(struct ipv6hdr));
463 goto looped_back;
464 }
465
466 dst_input(skb);
467
468 return -1;
469 }
470
471 /********************************
472 Routing header.
473 ********************************/
474
475 /* called with rcu_read_lock() */
ipv6_rthdr_rcv(struct sk_buff * skb)476 static int ipv6_rthdr_rcv(struct sk_buff *skb)
477 {
478 struct inet6_dev *idev = __in6_dev_get(skb->dev);
479 struct inet6_skb_parm *opt = IP6CB(skb);
480 struct in6_addr *addr = NULL;
481 struct in6_addr daddr;
482 int n, i;
483 struct ipv6_rt_hdr *hdr;
484 struct rt0_hdr *rthdr;
485 struct net *net = dev_net(skb->dev);
486 int accept_source_route = net->ipv6.devconf_all->accept_source_route;
487
488 idev = __in6_dev_get(skb->dev);
489 if (idev && accept_source_route > idev->cnf.accept_source_route)
490 accept_source_route = idev->cnf.accept_source_route;
491
492 if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
493 !pskb_may_pull(skb, (skb_transport_offset(skb) +
494 ((skb_transport_header(skb)[1] + 1) << 3)))) {
495 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
496 kfree_skb(skb);
497 return -1;
498 }
499
500 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
501
502 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
503 skb->pkt_type != PACKET_HOST) {
504 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
505 kfree_skb(skb);
506 return -1;
507 }
508
509 /* segment routing */
510 if (hdr->type == IPV6_SRCRT_TYPE_4)
511 return ipv6_srh_rcv(skb);
512
513 looped_back:
514 if (hdr->segments_left == 0) {
515 switch (hdr->type) {
516 #if IS_ENABLED(CONFIG_IPV6_MIP6)
517 case IPV6_SRCRT_TYPE_2:
518 /* Silently discard type 2 header unless it was
519 * processed by own
520 */
521 if (!addr) {
522 __IP6_INC_STATS(net, idev,
523 IPSTATS_MIB_INADDRERRORS);
524 kfree_skb(skb);
525 return -1;
526 }
527 break;
528 #endif
529 default:
530 break;
531 }
532
533 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
534 skb->transport_header += (hdr->hdrlen + 1) << 3;
535 opt->dst0 = opt->dst1;
536 opt->dst1 = 0;
537 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
538 return 1;
539 }
540
541 switch (hdr->type) {
542 #if IS_ENABLED(CONFIG_IPV6_MIP6)
543 case IPV6_SRCRT_TYPE_2:
544 if (accept_source_route < 0)
545 goto unknown_rh;
546 /* Silently discard invalid RTH type 2 */
547 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
548 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
549 kfree_skb(skb);
550 return -1;
551 }
552 break;
553 #endif
554 default:
555 goto unknown_rh;
556 }
557
558 /*
559 * This is the routing header forwarding algorithm from
560 * RFC 2460, page 16.
561 */
562
563 n = hdr->hdrlen >> 1;
564
565 if (hdr->segments_left > n) {
566 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
567 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
568 ((&hdr->segments_left) -
569 skb_network_header(skb)));
570 return -1;
571 }
572
573 /* We are about to mangle packet header. Be careful!
574 Do not damage packets queued somewhere.
575 */
576 if (skb_cloned(skb)) {
577 /* the copy is a forwarded packet */
578 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
579 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
580 IPSTATS_MIB_OUTDISCARDS);
581 kfree_skb(skb);
582 return -1;
583 }
584 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
585 }
586
587 if (skb->ip_summed == CHECKSUM_COMPLETE)
588 skb->ip_summed = CHECKSUM_NONE;
589
590 i = n - --hdr->segments_left;
591
592 rthdr = (struct rt0_hdr *) hdr;
593 addr = rthdr->addr;
594 addr += i - 1;
595
596 switch (hdr->type) {
597 #if IS_ENABLED(CONFIG_IPV6_MIP6)
598 case IPV6_SRCRT_TYPE_2:
599 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
600 (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
601 IPPROTO_ROUTING) < 0) {
602 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
603 kfree_skb(skb);
604 return -1;
605 }
606 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
607 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
608 kfree_skb(skb);
609 return -1;
610 }
611 break;
612 #endif
613 default:
614 break;
615 }
616
617 if (ipv6_addr_is_multicast(addr)) {
618 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
619 kfree_skb(skb);
620 return -1;
621 }
622
623 daddr = *addr;
624 *addr = ipv6_hdr(skb)->daddr;
625 ipv6_hdr(skb)->daddr = daddr;
626
627 skb_dst_drop(skb);
628 ip6_route_input(skb);
629 if (skb_dst(skb)->error) {
630 skb_push(skb, skb->data - skb_network_header(skb));
631 dst_input(skb);
632 return -1;
633 }
634
635 if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
636 if (ipv6_hdr(skb)->hop_limit <= 1) {
637 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
638 icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
639 0);
640 kfree_skb(skb);
641 return -1;
642 }
643 ipv6_hdr(skb)->hop_limit--;
644 goto looped_back;
645 }
646
647 skb_push(skb, skb->data - skb_network_header(skb));
648 dst_input(skb);
649 return -1;
650
651 unknown_rh:
652 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
653 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
654 (&hdr->type) - skb_network_header(skb));
655 return -1;
656 }
657
658 static const struct inet6_protocol rthdr_protocol = {
659 .handler = ipv6_rthdr_rcv,
660 .flags = INET6_PROTO_NOPOLICY,
661 };
662
663 static const struct inet6_protocol destopt_protocol = {
664 .handler = ipv6_destopt_rcv,
665 .flags = INET6_PROTO_NOPOLICY,
666 };
667
668 static const struct inet6_protocol nodata_protocol = {
669 .handler = dst_discard,
670 .flags = INET6_PROTO_NOPOLICY,
671 };
672
ipv6_exthdrs_init(void)673 int __init ipv6_exthdrs_init(void)
674 {
675 int ret;
676
677 ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
678 if (ret)
679 goto out;
680
681 ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
682 if (ret)
683 goto out_rthdr;
684
685 ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
686 if (ret)
687 goto out_destopt;
688
689 out:
690 return ret;
691 out_destopt:
692 inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
693 out_rthdr:
694 inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
695 goto out;
696 };
697
ipv6_exthdrs_exit(void)698 void ipv6_exthdrs_exit(void)
699 {
700 inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
701 inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
702 inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
703 }
704
705 /**********************************
706 Hop-by-hop options.
707 **********************************/
708
709 /*
710 * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
711 */
ipv6_skb_idev(struct sk_buff * skb)712 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
713 {
714 return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
715 }
716
ipv6_skb_net(struct sk_buff * skb)717 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
718 {
719 return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
720 }
721
722 /* Router Alert as of RFC 2711 */
723
ipv6_hop_ra(struct sk_buff * skb,int optoff)724 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
725 {
726 const unsigned char *nh = skb_network_header(skb);
727
728 if (nh[optoff + 1] == 2) {
729 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
730 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
731 return true;
732 }
733 net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
734 nh[optoff + 1]);
735 kfree_skb(skb);
736 return false;
737 }
738
739 /* Jumbo payload */
740
ipv6_hop_jumbo(struct sk_buff * skb,int optoff)741 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
742 {
743 const unsigned char *nh = skb_network_header(skb);
744 struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
745 struct net *net = ipv6_skb_net(skb);
746 u32 pkt_len;
747
748 if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
749 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
750 nh[optoff+1]);
751 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
752 goto drop;
753 }
754
755 pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
756 if (pkt_len <= IPV6_MAXPLEN) {
757 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
758 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
759 return false;
760 }
761 if (ipv6_hdr(skb)->payload_len) {
762 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
763 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
764 return false;
765 }
766
767 if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
768 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTRUNCATEDPKTS);
769 goto drop;
770 }
771
772 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
773 goto drop;
774
775 IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
776 return true;
777
778 drop:
779 kfree_skb(skb);
780 return false;
781 }
782
783 /* CALIPSO RFC 5570 */
784
ipv6_hop_calipso(struct sk_buff * skb,int optoff)785 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
786 {
787 const unsigned char *nh = skb_network_header(skb);
788
789 if (nh[optoff + 1] < 8)
790 goto drop;
791
792 if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
793 goto drop;
794
795 if (!calipso_validate(skb, nh + optoff))
796 goto drop;
797
798 return true;
799
800 drop:
801 kfree_skb(skb);
802 return false;
803 }
804
805 static const struct tlvtype_proc tlvprochopopt_lst[] = {
806 {
807 .type = IPV6_TLV_ROUTERALERT,
808 .func = ipv6_hop_ra,
809 },
810 {
811 .type = IPV6_TLV_JUMBO,
812 .func = ipv6_hop_jumbo,
813 },
814 {
815 .type = IPV6_TLV_CALIPSO,
816 .func = ipv6_hop_calipso,
817 },
818 { -1, }
819 };
820
ipv6_parse_hopopts(struct sk_buff * skb)821 int ipv6_parse_hopopts(struct sk_buff *skb)
822 {
823 struct inet6_skb_parm *opt = IP6CB(skb);
824 struct net *net = dev_net(skb->dev);
825 int extlen;
826
827 /*
828 * skb_network_header(skb) is equal to skb->data, and
829 * skb_network_header_len(skb) is always equal to
830 * sizeof(struct ipv6hdr) by definition of
831 * hop-by-hop options.
832 */
833 if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
834 !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
835 ((skb_transport_header(skb)[1] + 1) << 3)))) {
836 fail_and_free:
837 kfree_skb(skb);
838 return -1;
839 }
840
841 extlen = (skb_transport_header(skb)[1] + 1) << 3;
842 if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
843 goto fail_and_free;
844
845 opt->flags |= IP6SKB_HOPBYHOP;
846 if (ip6_parse_tlv(tlvprochopopt_lst, skb,
847 init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
848 skb->transport_header += extlen;
849 opt = IP6CB(skb);
850 opt->nhoff = sizeof(struct ipv6hdr);
851 return 1;
852 }
853 return -1;
854 }
855
856 /*
857 * Creating outbound headers.
858 *
859 * "build" functions work when skb is filled from head to tail (datagram)
860 * "push" functions work when headers are added from tail to head (tcp)
861 *
862 * In both cases we assume, that caller reserved enough room
863 * for headers.
864 */
865
ipv6_push_rthdr0(struct sk_buff * skb,u8 * proto,struct ipv6_rt_hdr * opt,struct in6_addr ** addr_p,struct in6_addr * saddr)866 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
867 struct ipv6_rt_hdr *opt,
868 struct in6_addr **addr_p, struct in6_addr *saddr)
869 {
870 struct rt0_hdr *phdr, *ihdr;
871 int hops;
872
873 ihdr = (struct rt0_hdr *) opt;
874
875 phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
876 memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
877
878 hops = ihdr->rt_hdr.hdrlen >> 1;
879
880 if (hops > 1)
881 memcpy(phdr->addr, ihdr->addr + 1,
882 (hops - 1) * sizeof(struct in6_addr));
883
884 phdr->addr[hops - 1] = **addr_p;
885 *addr_p = ihdr->addr;
886
887 phdr->rt_hdr.nexthdr = *proto;
888 *proto = NEXTHDR_ROUTING;
889 }
890
ipv6_push_rthdr4(struct sk_buff * skb,u8 * proto,struct ipv6_rt_hdr * opt,struct in6_addr ** addr_p,struct in6_addr * saddr)891 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
892 struct ipv6_rt_hdr *opt,
893 struct in6_addr **addr_p, struct in6_addr *saddr)
894 {
895 struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
896 int plen, hops;
897
898 sr_ihdr = (struct ipv6_sr_hdr *)opt;
899 plen = (sr_ihdr->hdrlen + 1) << 3;
900
901 sr_phdr = skb_push(skb, plen);
902 memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
903
904 hops = sr_ihdr->first_segment + 1;
905 memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
906 (hops - 1) * sizeof(struct in6_addr));
907
908 sr_phdr->segments[0] = **addr_p;
909 *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
910
911 if (sr_ihdr->hdrlen > hops * 2) {
912 int tlvs_offset, tlvs_length;
913
914 tlvs_offset = (1 + hops * 2) << 3;
915 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
916 memcpy((char *)sr_phdr + tlvs_offset,
917 (char *)sr_ihdr + tlvs_offset, tlvs_length);
918 }
919
920 #ifdef CONFIG_IPV6_SEG6_HMAC
921 if (sr_has_hmac(sr_phdr)) {
922 struct net *net = NULL;
923
924 if (skb->dev)
925 net = dev_net(skb->dev);
926 else if (skb->sk)
927 net = sock_net(skb->sk);
928
929 WARN_ON(!net);
930
931 if (net)
932 seg6_push_hmac(net, saddr, sr_phdr);
933 }
934 #endif
935
936 sr_phdr->nexthdr = *proto;
937 *proto = NEXTHDR_ROUTING;
938 }
939
ipv6_push_rthdr(struct sk_buff * skb,u8 * proto,struct ipv6_rt_hdr * opt,struct in6_addr ** addr_p,struct in6_addr * saddr)940 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
941 struct ipv6_rt_hdr *opt,
942 struct in6_addr **addr_p, struct in6_addr *saddr)
943 {
944 switch (opt->type) {
945 case IPV6_SRCRT_TYPE_0:
946 case IPV6_SRCRT_STRICT:
947 case IPV6_SRCRT_TYPE_2:
948 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
949 break;
950 case IPV6_SRCRT_TYPE_4:
951 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
952 break;
953 default:
954 break;
955 }
956 }
957
ipv6_push_exthdr(struct sk_buff * skb,u8 * proto,u8 type,struct ipv6_opt_hdr * opt)958 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
959 {
960 struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
961
962 memcpy(h, opt, ipv6_optlen(opt));
963 h->nexthdr = *proto;
964 *proto = type;
965 }
966
ipv6_push_nfrag_opts(struct sk_buff * skb,struct ipv6_txoptions * opt,u8 * proto,struct in6_addr ** daddr,struct in6_addr * saddr)967 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
968 u8 *proto,
969 struct in6_addr **daddr, struct in6_addr *saddr)
970 {
971 if (opt->srcrt) {
972 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
973 /*
974 * IPV6_RTHDRDSTOPTS is ignored
975 * unless IPV6_RTHDR is set (RFC3542).
976 */
977 if (opt->dst0opt)
978 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
979 }
980 if (opt->hopopt)
981 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
982 }
983
ipv6_push_frag_opts(struct sk_buff * skb,struct ipv6_txoptions * opt,u8 * proto)984 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
985 {
986 if (opt->dst1opt)
987 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
988 }
989 EXPORT_SYMBOL(ipv6_push_frag_opts);
990
991 struct ipv6_txoptions *
ipv6_dup_options(struct sock * sk,struct ipv6_txoptions * opt)992 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
993 {
994 struct ipv6_txoptions *opt2;
995
996 opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
997 if (opt2) {
998 long dif = (char *)opt2 - (char *)opt;
999 memcpy(opt2, opt, opt->tot_len);
1000 if (opt2->hopopt)
1001 *((char **)&opt2->hopopt) += dif;
1002 if (opt2->dst0opt)
1003 *((char **)&opt2->dst0opt) += dif;
1004 if (opt2->dst1opt)
1005 *((char **)&opt2->dst1opt) += dif;
1006 if (opt2->srcrt)
1007 *((char **)&opt2->srcrt) += dif;
1008 refcount_set(&opt2->refcnt, 1);
1009 }
1010 return opt2;
1011 }
1012 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1013
ipv6_renew_option(int renewtype,struct ipv6_opt_hdr ** dest,struct ipv6_opt_hdr * old,struct ipv6_opt_hdr * new,int newtype,char ** p)1014 static void ipv6_renew_option(int renewtype,
1015 struct ipv6_opt_hdr **dest,
1016 struct ipv6_opt_hdr *old,
1017 struct ipv6_opt_hdr *new,
1018 int newtype, char **p)
1019 {
1020 struct ipv6_opt_hdr *src;
1021
1022 src = (renewtype == newtype ? new : old);
1023 if (!src)
1024 return;
1025
1026 memcpy(*p, src, ipv6_optlen(src));
1027 *dest = (struct ipv6_opt_hdr *)*p;
1028 *p += CMSG_ALIGN(ipv6_optlen(*dest));
1029 }
1030
1031 /**
1032 * ipv6_renew_options - replace a specific ext hdr with a new one.
1033 *
1034 * @sk: sock from which to allocate memory
1035 * @opt: original options
1036 * @newtype: option type to replace in @opt
1037 * @newopt: new option of type @newtype to replace (user-mem)
1038 * @newoptlen: length of @newopt
1039 *
1040 * Returns a new set of options which is a copy of @opt with the
1041 * option type @newtype replaced with @newopt.
1042 *
1043 * @opt may be NULL, in which case a new set of options is returned
1044 * containing just @newopt.
1045 *
1046 * @newopt may be NULL, in which case the specified option type is
1047 * not copied into the new set of options.
1048 *
1049 * The new set of options is allocated from the socket option memory
1050 * buffer of @sk.
1051 */
1052 struct ipv6_txoptions *
ipv6_renew_options(struct sock * sk,struct ipv6_txoptions * opt,int newtype,struct ipv6_opt_hdr * newopt)1053 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1054 int newtype, struct ipv6_opt_hdr *newopt)
1055 {
1056 int tot_len = 0;
1057 char *p;
1058 struct ipv6_txoptions *opt2;
1059
1060 if (opt) {
1061 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1062 tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1063 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1064 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1065 if (newtype != IPV6_RTHDR && opt->srcrt)
1066 tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1067 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1068 tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1069 }
1070
1071 if (newopt)
1072 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1073
1074 if (!tot_len)
1075 return NULL;
1076
1077 tot_len += sizeof(*opt2);
1078 opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1079 if (!opt2)
1080 return ERR_PTR(-ENOBUFS);
1081
1082 memset(opt2, 0, tot_len);
1083 refcount_set(&opt2->refcnt, 1);
1084 opt2->tot_len = tot_len;
1085 p = (char *)(opt2 + 1);
1086
1087 ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1088 (opt ? opt->hopopt : NULL),
1089 newopt, newtype, &p);
1090 ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1091 (opt ? opt->dst0opt : NULL),
1092 newopt, newtype, &p);
1093 ipv6_renew_option(IPV6_RTHDR,
1094 (struct ipv6_opt_hdr **)&opt2->srcrt,
1095 (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1096 newopt, newtype, &p);
1097 ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1098 (opt ? opt->dst1opt : NULL),
1099 newopt, newtype, &p);
1100
1101 opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1102 (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1103 (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1104 opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1105
1106 return opt2;
1107 }
1108
ipv6_fixup_options(struct ipv6_txoptions * opt_space,struct ipv6_txoptions * opt)1109 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1110 struct ipv6_txoptions *opt)
1111 {
1112 /*
1113 * ignore the dest before srcrt unless srcrt is being included.
1114 * --yoshfuji
1115 */
1116 if (opt && opt->dst0opt && !opt->srcrt) {
1117 if (opt_space != opt) {
1118 memcpy(opt_space, opt, sizeof(*opt_space));
1119 opt = opt_space;
1120 }
1121 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1122 opt->dst0opt = NULL;
1123 }
1124
1125 return opt;
1126 }
1127 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
1128
1129 /**
1130 * fl6_update_dst - update flowi destination address with info given
1131 * by srcrt option, if any.
1132 *
1133 * @fl6: flowi6 for which daddr is to be updated
1134 * @opt: struct ipv6_txoptions in which to look for srcrt opt
1135 * @orig: copy of original daddr address if modified
1136 *
1137 * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1138 * and initial value of fl6->daddr set in orig
1139 */
fl6_update_dst(struct flowi6 * fl6,const struct ipv6_txoptions * opt,struct in6_addr * orig)1140 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1141 const struct ipv6_txoptions *opt,
1142 struct in6_addr *orig)
1143 {
1144 if (!opt || !opt->srcrt)
1145 return NULL;
1146
1147 *orig = fl6->daddr;
1148
1149 switch (opt->srcrt->type) {
1150 case IPV6_SRCRT_TYPE_0:
1151 case IPV6_SRCRT_STRICT:
1152 case IPV6_SRCRT_TYPE_2:
1153 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1154 break;
1155 case IPV6_SRCRT_TYPE_4:
1156 {
1157 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1158
1159 fl6->daddr = srh->segments[srh->segments_left];
1160 break;
1161 }
1162 default:
1163 return NULL;
1164 }
1165
1166 return orig;
1167 }
1168 EXPORT_SYMBOL_GPL(fl6_update_dst);
1169
