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Linux/net/ipv6/exthdrs.c

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  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 #include <net/rpl.h>
 52 
 53 #include <linux/uaccess.h>
 54 
 55 /*
 56  *      Parsing tlv encoded headers.
 57  *
 58  *      Parsing function "func" returns true, if parsing succeed
 59  *      and false, if it failed.
 60  *      It MUST NOT touch skb->h.
 61  */
 62 
 63 struct tlvtype_proc {
 64         int     type;
 65         bool    (*func)(struct sk_buff *skb, int offset);
 66 };
 67 
 68 /*********************
 69   Generic functions
 70  *********************/
 71 
 72 /* An unknown option is detected, decide what to do */
 73 
 74 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
 75                                bool disallow_unknowns)
 76 {
 77         if (disallow_unknowns) {
 78                 /* If unknown TLVs are disallowed by configuration
 79                  * then always silently drop packet. Note this also
 80                  * means no ICMP parameter problem is sent which
 81                  * could be a good property to mitigate a reflection DOS
 82                  * attack.
 83                  */
 84 
 85                 goto drop;
 86         }
 87 
 88         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
 89         case 0: /* ignore */
 90                 return true;
 91 
 92         case 1: /* drop packet */
 93                 break;
 94 
 95         case 3: /* Send ICMP if not a multicast address and drop packet */
 96                 /* Actually, it is redundant check. icmp_send
 97                    will recheck in any case.
 98                  */
 99                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
100                         break;
101                 fallthrough;
102         case 2: /* send ICMP PARM PROB regardless and drop packet */
103                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
104                 return false;
105         }
106 
107 drop:
108         kfree_skb(skb);
109         return false;
110 }
111 
112 /* Parse tlv encoded option header (hop-by-hop or destination) */
113 
114 static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
115                           struct sk_buff *skb,
116                           int max_count)
117 {
118         int len = (skb_transport_header(skb)[1] + 1) << 3;
119         const unsigned char *nh = skb_network_header(skb);
120         int off = skb_network_header_len(skb);
121         const struct tlvtype_proc *curr;
122         bool disallow_unknowns = false;
123         int tlv_count = 0;
124         int padlen = 0;
125 
126         if (unlikely(max_count < 0)) {
127                 disallow_unknowns = true;
128                 max_count = -max_count;
129         }
130 
131         if (skb_transport_offset(skb) + len > skb_headlen(skb))
132                 goto bad;
133 
134         off += 2;
135         len -= 2;
136 
137         while (len > 0) {
138                 int optlen = nh[off + 1] + 2;
139                 int i;
140 
141                 switch (nh[off]) {
142                 case IPV6_TLV_PAD1:
143                         optlen = 1;
144                         padlen++;
145                         if (padlen > 7)
146                                 goto bad;
147                         break;
148 
149                 case IPV6_TLV_PADN:
150                         /* RFC 2460 states that the purpose of PadN is
151                          * to align the containing header to multiples
152                          * of 8. 7 is therefore the highest valid value.
153                          * See also RFC 4942, Section 2.1.9.5.
154                          */
155                         padlen += optlen;
156                         if (padlen > 7)
157                                 goto bad;
158                         /* RFC 4942 recommends receiving hosts to
159                          * actively check PadN payload to contain
160                          * only zeroes.
161                          */
162                         for (i = 2; i < optlen; i++) {
163                                 if (nh[off + i] != 0)
164                                         goto bad;
165                         }
166                         break;
167 
168                 default: /* Other TLV code so scan list */
169                         if (optlen > len)
170                                 goto bad;
171 
172                         tlv_count++;
173                         if (tlv_count > max_count)
174                                 goto bad;
175 
176                         for (curr = procs; curr->type >= 0; curr++) {
177                                 if (curr->type == nh[off]) {
178                                         /* type specific length/alignment
179                                            checks will be performed in the
180                                            func(). */
181                                         if (curr->func(skb, off) == false)
182                                                 return false;
183                                         break;
184                                 }
185                         }
186                         if (curr->type < 0 &&
187                             !ip6_tlvopt_unknown(skb, off, disallow_unknowns))
188                                 return false;
189 
190                         padlen = 0;
191                         break;
192                 }
193                 off += optlen;
194                 len -= optlen;
195         }
196 
197         if (len == 0)
198                 return true;
199 bad:
200         kfree_skb(skb);
201         return false;
202 }
203 
204 /*****************************
205   Destination options header.
206  *****************************/
207 
208 #if IS_ENABLED(CONFIG_IPV6_MIP6)
209 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
210 {
211         struct ipv6_destopt_hao *hao;
212         struct inet6_skb_parm *opt = IP6CB(skb);
213         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
214         int ret;
215 
216         if (opt->dsthao) {
217                 net_dbg_ratelimited("hao duplicated\n");
218                 goto discard;
219         }
220         opt->dsthao = opt->dst1;
221         opt->dst1 = 0;
222 
223         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
224 
225         if (hao->length != 16) {
226                 net_dbg_ratelimited("hao invalid option length = %d\n",
227                                     hao->length);
228                 goto discard;
229         }
230 
231         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
232                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
233                                     &hao->addr);
234                 goto discard;
235         }
236 
237         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
238                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
239         if (unlikely(ret < 0))
240                 goto discard;
241 
242         if (skb_cloned(skb)) {
243                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
244                         goto discard;
245 
246                 /* update all variable using below by copied skbuff */
247                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
248                                                   optoff);
249                 ipv6h = ipv6_hdr(skb);
250         }
251 
252         if (skb->ip_summed == CHECKSUM_COMPLETE)
253                 skb->ip_summed = CHECKSUM_NONE;
254 
255         swap(ipv6h->saddr, hao->addr);
256 
257         if (skb->tstamp == 0)
258                 __net_timestamp(skb);
259 
260         return true;
261 
262  discard:
263         kfree_skb(skb);
264         return false;
265 }
266 #endif
267 
268 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
269 #if IS_ENABLED(CONFIG_IPV6_MIP6)
270         {
271                 .type   = IPV6_TLV_HAO,
272                 .func   = ipv6_dest_hao,
273         },
274 #endif
275         {-1,                    NULL}
276 };
277 
278 static int ipv6_destopt_rcv(struct sk_buff *skb)
279 {
280         struct inet6_dev *idev = __in6_dev_get(skb->dev);
281         struct inet6_skb_parm *opt = IP6CB(skb);
282 #if IS_ENABLED(CONFIG_IPV6_MIP6)
283         __u16 dstbuf;
284 #endif
285         struct dst_entry *dst = skb_dst(skb);
286         struct net *net = dev_net(skb->dev);
287         int extlen;
288 
289         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
290             !pskb_may_pull(skb, (skb_transport_offset(skb) +
291                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
292                 __IP6_INC_STATS(dev_net(dst->dev), idev,
293                                 IPSTATS_MIB_INHDRERRORS);
294 fail_and_free:
295                 kfree_skb(skb);
296                 return -1;
297         }
298 
299         extlen = (skb_transport_header(skb)[1] + 1) << 3;
300         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
301                 goto fail_and_free;
302 
303         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
304 #if IS_ENABLED(CONFIG_IPV6_MIP6)
305         dstbuf = opt->dst1;
306 #endif
307 
308         if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
309                           init_net.ipv6.sysctl.max_dst_opts_cnt)) {
310                 skb->transport_header += extlen;
311                 opt = IP6CB(skb);
312 #if IS_ENABLED(CONFIG_IPV6_MIP6)
313                 opt->nhoff = dstbuf;
314 #else
315                 opt->nhoff = opt->dst1;
316 #endif
317                 return 1;
318         }
319 
320         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
321         return -1;
322 }
323 
324 static void seg6_update_csum(struct sk_buff *skb)
325 {
326         struct ipv6_sr_hdr *hdr;
327         struct in6_addr *addr;
328         __be32 from, to;
329 
330         /* srh is at transport offset and seg_left is already decremented
331          * but daddr is not yet updated with next segment
332          */
333 
334         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
335         addr = hdr->segments + hdr->segments_left;
336 
337         hdr->segments_left++;
338         from = *(__be32 *)hdr;
339 
340         hdr->segments_left--;
341         to = *(__be32 *)hdr;
342 
343         /* update skb csum with diff resulting from seg_left decrement */
344 
345         update_csum_diff4(skb, from, to);
346 
347         /* compute csum diff between current and next segment and update */
348 
349         update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
350                            (__be32 *)addr);
351 }
352 
353 static int ipv6_srh_rcv(struct sk_buff *skb)
354 {
355         struct inet6_skb_parm *opt = IP6CB(skb);
356         struct net *net = dev_net(skb->dev);
357         struct ipv6_sr_hdr *hdr;
358         struct inet6_dev *idev;
359         struct in6_addr *addr;
360         int accept_seg6;
361 
362         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
363 
364         idev = __in6_dev_get(skb->dev);
365 
366         accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
367         if (accept_seg6 > idev->cnf.seg6_enabled)
368                 accept_seg6 = idev->cnf.seg6_enabled;
369 
370         if (!accept_seg6) {
371                 kfree_skb(skb);
372                 return -1;
373         }
374 
375 #ifdef CONFIG_IPV6_SEG6_HMAC
376         if (!seg6_hmac_validate_skb(skb)) {
377                 kfree_skb(skb);
378                 return -1;
379         }
380 #endif
381 
382 looped_back:
383         if (hdr->segments_left == 0) {
384                 if (hdr->nexthdr == NEXTHDR_IPV6) {
385                         int offset = (hdr->hdrlen + 1) << 3;
386 
387                         skb_postpull_rcsum(skb, skb_network_header(skb),
388                                            skb_network_header_len(skb));
389 
390                         if (!pskb_pull(skb, offset)) {
391                                 kfree_skb(skb);
392                                 return -1;
393                         }
394                         skb_postpull_rcsum(skb, skb_transport_header(skb),
395                                            offset);
396 
397                         skb_reset_network_header(skb);
398                         skb_reset_transport_header(skb);
399                         skb->encapsulation = 0;
400 
401                         __skb_tunnel_rx(skb, skb->dev, net);
402 
403                         netif_rx(skb);
404                         return -1;
405                 }
406 
407                 opt->srcrt = skb_network_header_len(skb);
408                 opt->lastopt = opt->srcrt;
409                 skb->transport_header += (hdr->hdrlen + 1) << 3;
410                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
411 
412                 return 1;
413         }
414 
415         if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
416                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
417                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
418                                   ((&hdr->segments_left) -
419                                    skb_network_header(skb)));
420                 return -1;
421         }
422 
423         if (skb_cloned(skb)) {
424                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
425                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
426                                         IPSTATS_MIB_OUTDISCARDS);
427                         kfree_skb(skb);
428                         return -1;
429                 }
430         }
431 
432         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
433 
434         hdr->segments_left--;
435         addr = hdr->segments + hdr->segments_left;
436 
437         skb_push(skb, sizeof(struct ipv6hdr));
438 
439         if (skb->ip_summed == CHECKSUM_COMPLETE)
440                 seg6_update_csum(skb);
441 
442         ipv6_hdr(skb)->daddr = *addr;
443 
444         skb_dst_drop(skb);
445 
446         ip6_route_input(skb);
447 
448         if (skb_dst(skb)->error) {
449                 dst_input(skb);
450                 return -1;
451         }
452 
453         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
454                 if (ipv6_hdr(skb)->hop_limit <= 1) {
455                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
456                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
457                                     ICMPV6_EXC_HOPLIMIT, 0);
458                         kfree_skb(skb);
459                         return -1;
460                 }
461                 ipv6_hdr(skb)->hop_limit--;
462 
463                 skb_pull(skb, sizeof(struct ipv6hdr));
464                 goto looped_back;
465         }
466 
467         dst_input(skb);
468 
469         return -1;
470 }
471 
472 static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
473 {
474         struct ipv6_rpl_sr_hdr *hdr, *ohdr, *chdr;
475         struct inet6_skb_parm *opt = IP6CB(skb);
476         struct net *net = dev_net(skb->dev);
477         struct inet6_dev *idev;
478         struct ipv6hdr *oldhdr;
479         struct in6_addr addr;
480         unsigned char *buf;
481         int accept_rpl_seg;
482         int i, err;
483         u64 n = 0;
484         u32 r;
485 
486         idev = __in6_dev_get(skb->dev);
487 
488         accept_rpl_seg = net->ipv6.devconf_all->rpl_seg_enabled;
489         if (accept_rpl_seg > idev->cnf.rpl_seg_enabled)
490                 accept_rpl_seg = idev->cnf.rpl_seg_enabled;
491 
492         if (!accept_rpl_seg) {
493                 kfree_skb(skb);
494                 return -1;
495         }
496 
497 looped_back:
498         hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
499 
500         if (hdr->segments_left == 0) {
501                 if (hdr->nexthdr == NEXTHDR_IPV6) {
502                         int offset = (hdr->hdrlen + 1) << 3;
503 
504                         skb_postpull_rcsum(skb, skb_network_header(skb),
505                                            skb_network_header_len(skb));
506 
507                         if (!pskb_pull(skb, offset)) {
508                                 kfree_skb(skb);
509                                 return -1;
510                         }
511                         skb_postpull_rcsum(skb, skb_transport_header(skb),
512                                            offset);
513 
514                         skb_reset_network_header(skb);
515                         skb_reset_transport_header(skb);
516                         skb->encapsulation = 0;
517 
518                         __skb_tunnel_rx(skb, skb->dev, net);
519 
520                         netif_rx(skb);
521                         return -1;
522                 }
523 
524                 opt->srcrt = skb_network_header_len(skb);
525                 opt->lastopt = opt->srcrt;
526                 skb->transport_header += (hdr->hdrlen + 1) << 3;
527                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
528 
529                 return 1;
530         }
531 
532         if (!pskb_may_pull(skb, sizeof(*hdr))) {
533                 kfree_skb(skb);
534                 return -1;
535         }
536 
537         n = (hdr->hdrlen << 3) - hdr->pad - (16 - hdr->cmpre);
538         r = do_div(n, (16 - hdr->cmpri));
539         /* checks if calculation was without remainder and n fits into
540          * unsigned char which is segments_left field. Should not be
541          * higher than that.
542          */
543         if (r || (n + 1) > 255) {
544                 kfree_skb(skb);
545                 return -1;
546         }
547 
548         if (hdr->segments_left > n + 1) {
549                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
550                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
551                                   ((&hdr->segments_left) -
552                                    skb_network_header(skb)));
553                 return -1;
554         }
555 
556         if (skb_cloned(skb)) {
557                 if (pskb_expand_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE, 0,
558                                      GFP_ATOMIC)) {
559                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
560                                         IPSTATS_MIB_OUTDISCARDS);
561                         kfree_skb(skb);
562                         return -1;
563                 }
564         } else {
565                 err = skb_cow_head(skb, IPV6_RPL_SRH_WORST_SWAP_SIZE);
566                 if (unlikely(err)) {
567                         kfree_skb(skb);
568                         return -1;
569                 }
570         }
571 
572         hdr = (struct ipv6_rpl_sr_hdr *)skb_transport_header(skb);
573 
574         if (!pskb_may_pull(skb, ipv6_rpl_srh_size(n, hdr->cmpri,
575                                                   hdr->cmpre))) {
576                 kfree_skb(skb);
577                 return -1;
578         }
579 
580         hdr->segments_left--;
581         i = n - hdr->segments_left;
582 
583         buf = kzalloc(ipv6_rpl_srh_alloc_size(n + 1) * 2, GFP_ATOMIC);
584         if (unlikely(!buf)) {
585                 kfree_skb(skb);
586                 return -1;
587         }
588 
589         ohdr = (struct ipv6_rpl_sr_hdr *)buf;
590         ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n);
591         chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3));
592 
593         if ((ipv6_addr_type(&ipv6_hdr(skb)->daddr) & IPV6_ADDR_MULTICAST) ||
594             (ipv6_addr_type(&ohdr->rpl_segaddr[i]) & IPV6_ADDR_MULTICAST)) {
595                 kfree_skb(skb);
596                 kfree(buf);
597                 return -1;
598         }
599 
600         err = ipv6_chk_rpl_srh_loop(net, ohdr->rpl_segaddr, n + 1);
601         if (err) {
602                 icmpv6_send(skb, ICMPV6_PARAMPROB, 0, 0);
603                 kfree_skb(skb);
604                 kfree(buf);
605                 return -1;
606         }
607 
608         addr = ipv6_hdr(skb)->daddr;
609         ipv6_hdr(skb)->daddr = ohdr->rpl_segaddr[i];
610         ohdr->rpl_segaddr[i] = addr;
611 
612         ipv6_rpl_srh_compress(chdr, ohdr, &ipv6_hdr(skb)->daddr, n);
613 
614         oldhdr = ipv6_hdr(skb);
615 
616         skb_pull(skb, ((hdr->hdrlen + 1) << 3));
617         skb_postpull_rcsum(skb, oldhdr,
618                            sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3));
619         skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr));
620         skb_reset_network_header(skb);
621         skb_mac_header_rebuild(skb);
622         skb_set_transport_header(skb, sizeof(struct ipv6hdr));
623 
624         memmove(ipv6_hdr(skb), oldhdr, sizeof(struct ipv6hdr));
625         memcpy(skb_transport_header(skb), chdr, (chdr->hdrlen + 1) << 3);
626 
627         ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
628         skb_postpush_rcsum(skb, ipv6_hdr(skb),
629                            sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3));
630 
631         kfree(buf);
632 
633         skb_dst_drop(skb);
634 
635         ip6_route_input(skb);
636 
637         if (skb_dst(skb)->error) {
638                 dst_input(skb);
639                 return -1;
640         }
641 
642         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
643                 if (ipv6_hdr(skb)->hop_limit <= 1) {
644                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
645                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
646                                     ICMPV6_EXC_HOPLIMIT, 0);
647                         kfree_skb(skb);
648                         return -1;
649                 }
650                 ipv6_hdr(skb)->hop_limit--;
651 
652                 skb_pull(skb, sizeof(struct ipv6hdr));
653                 goto looped_back;
654         }
655 
656         dst_input(skb);
657 
658         return -1;
659 }
660 
661 /********************************
662   Routing header.
663  ********************************/
664 
665 /* called with rcu_read_lock() */
666 static int ipv6_rthdr_rcv(struct sk_buff *skb)
667 {
668         struct inet6_dev *idev = __in6_dev_get(skb->dev);
669         struct inet6_skb_parm *opt = IP6CB(skb);
670         struct in6_addr *addr = NULL;
671         struct in6_addr daddr;
672         int n, i;
673         struct ipv6_rt_hdr *hdr;
674         struct rt0_hdr *rthdr;
675         struct net *net = dev_net(skb->dev);
676         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
677 
678         idev = __in6_dev_get(skb->dev);
679         if (idev && accept_source_route > idev->cnf.accept_source_route)
680                 accept_source_route = idev->cnf.accept_source_route;
681 
682         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
683             !pskb_may_pull(skb, (skb_transport_offset(skb) +
684                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
685                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
686                 kfree_skb(skb);
687                 return -1;
688         }
689 
690         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
691 
692         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
693             skb->pkt_type != PACKET_HOST) {
694                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
695                 kfree_skb(skb);
696                 return -1;
697         }
698 
699         switch (hdr->type) {
700         case IPV6_SRCRT_TYPE_4:
701                 /* segment routing */
702                 return ipv6_srh_rcv(skb);
703         case IPV6_SRCRT_TYPE_3:
704                 /* rpl segment routing */
705                 return ipv6_rpl_srh_rcv(skb);
706         default:
707                 break;
708         }
709 
710 looped_back:
711         if (hdr->segments_left == 0) {
712                 switch (hdr->type) {
713 #if IS_ENABLED(CONFIG_IPV6_MIP6)
714                 case IPV6_SRCRT_TYPE_2:
715                         /* Silently discard type 2 header unless it was
716                          * processed by own
717                          */
718                         if (!addr) {
719                                 __IP6_INC_STATS(net, idev,
720                                                 IPSTATS_MIB_INADDRERRORS);
721                                 kfree_skb(skb);
722                                 return -1;
723                         }
724                         break;
725 #endif
726                 default:
727                         break;
728                 }
729 
730                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
731                 skb->transport_header += (hdr->hdrlen + 1) << 3;
732                 opt->dst0 = opt->dst1;
733                 opt->dst1 = 0;
734                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
735                 return 1;
736         }
737 
738         switch (hdr->type) {
739 #if IS_ENABLED(CONFIG_IPV6_MIP6)
740         case IPV6_SRCRT_TYPE_2:
741                 if (accept_source_route < 0)
742                         goto unknown_rh;
743                 /* Silently discard invalid RTH type 2 */
744                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
745                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
746                         kfree_skb(skb);
747                         return -1;
748                 }
749                 break;
750 #endif
751         default:
752                 goto unknown_rh;
753         }
754 
755         /*
756          *      This is the routing header forwarding algorithm from
757          *      RFC 2460, page 16.
758          */
759 
760         n = hdr->hdrlen >> 1;
761 
762         if (hdr->segments_left > n) {
763                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
764                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
765                                   ((&hdr->segments_left) -
766                                    skb_network_header(skb)));
767                 return -1;
768         }
769 
770         /* We are about to mangle packet header. Be careful!
771            Do not damage packets queued somewhere.
772          */
773         if (skb_cloned(skb)) {
774                 /* the copy is a forwarded packet */
775                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
776                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
777                                         IPSTATS_MIB_OUTDISCARDS);
778                         kfree_skb(skb);
779                         return -1;
780                 }
781                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
782         }
783 
784         if (skb->ip_summed == CHECKSUM_COMPLETE)
785                 skb->ip_summed = CHECKSUM_NONE;
786 
787         i = n - --hdr->segments_left;
788 
789         rthdr = (struct rt0_hdr *) hdr;
790         addr = rthdr->addr;
791         addr += i - 1;
792 
793         switch (hdr->type) {
794 #if IS_ENABLED(CONFIG_IPV6_MIP6)
795         case IPV6_SRCRT_TYPE_2:
796                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
797                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
798                                      IPPROTO_ROUTING) < 0) {
799                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
800                         kfree_skb(skb);
801                         return -1;
802                 }
803                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
804                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
805                         kfree_skb(skb);
806                         return -1;
807                 }
808                 break;
809 #endif
810         default:
811                 break;
812         }
813 
814         if (ipv6_addr_is_multicast(addr)) {
815                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
816                 kfree_skb(skb);
817                 return -1;
818         }
819 
820         daddr = *addr;
821         *addr = ipv6_hdr(skb)->daddr;
822         ipv6_hdr(skb)->daddr = daddr;
823 
824         skb_dst_drop(skb);
825         ip6_route_input(skb);
826         if (skb_dst(skb)->error) {
827                 skb_push(skb, skb->data - skb_network_header(skb));
828                 dst_input(skb);
829                 return -1;
830         }
831 
832         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
833                 if (ipv6_hdr(skb)->hop_limit <= 1) {
834                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
835                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
836                                     0);
837                         kfree_skb(skb);
838                         return -1;
839                 }
840                 ipv6_hdr(skb)->hop_limit--;
841                 goto looped_back;
842         }
843 
844         skb_push(skb, skb->data - skb_network_header(skb));
845         dst_input(skb);
846         return -1;
847 
848 unknown_rh:
849         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
850         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
851                           (&hdr->type) - skb_network_header(skb));
852         return -1;
853 }
854 
855 static const struct inet6_protocol rthdr_protocol = {
856         .handler        =       ipv6_rthdr_rcv,
857         .flags          =       INET6_PROTO_NOPOLICY,
858 };
859 
860 static const struct inet6_protocol destopt_protocol = {
861         .handler        =       ipv6_destopt_rcv,
862         .flags          =       INET6_PROTO_NOPOLICY,
863 };
864 
865 static const struct inet6_protocol nodata_protocol = {
866         .handler        =       dst_discard,
867         .flags          =       INET6_PROTO_NOPOLICY,
868 };
869 
870 int __init ipv6_exthdrs_init(void)
871 {
872         int ret;
873 
874         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
875         if (ret)
876                 goto out;
877 
878         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
879         if (ret)
880                 goto out_rthdr;
881 
882         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
883         if (ret)
884                 goto out_destopt;
885 
886 out:
887         return ret;
888 out_destopt:
889         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
890 out_rthdr:
891         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
892         goto out;
893 };
894 
895 void ipv6_exthdrs_exit(void)
896 {
897         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
898         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
899         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
900 }
901 
902 /**********************************
903   Hop-by-hop options.
904  **********************************/
905 
906 /*
907  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
908  */
909 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
910 {
911         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
912 }
913 
914 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
915 {
916         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
917 }
918 
919 /* Router Alert as of RFC 2711 */
920 
921 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
922 {
923         const unsigned char *nh = skb_network_header(skb);
924 
925         if (nh[optoff + 1] == 2) {
926                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
927                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
928                 return true;
929         }
930         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
931                             nh[optoff + 1]);
932         kfree_skb(skb);
933         return false;
934 }
935 
936 /* Jumbo payload */
937 
938 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
939 {
940         const unsigned char *nh = skb_network_header(skb);
941         struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
942         struct net *net = ipv6_skb_net(skb);
943         u32 pkt_len;
944 
945         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
946                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
947                                     nh[optoff+1]);
948                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
949                 goto drop;
950         }
951 
952         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
953         if (pkt_len <= IPV6_MAXPLEN) {
954                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
955                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
956                 return false;
957         }
958         if (ipv6_hdr(skb)->payload_len) {
959                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
960                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
961                 return false;
962         }
963 
964         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
965                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTRUNCATEDPKTS);
966                 goto drop;
967         }
968 
969         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
970                 goto drop;
971 
972         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
973         return true;
974 
975 drop:
976         kfree_skb(skb);
977         return false;
978 }
979 
980 /* CALIPSO RFC 5570 */
981 
982 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
983 {
984         const unsigned char *nh = skb_network_header(skb);
985 
986         if (nh[optoff + 1] < 8)
987                 goto drop;
988 
989         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
990                 goto drop;
991 
992         if (!calipso_validate(skb, nh + optoff))
993                 goto drop;
994 
995         return true;
996 
997 drop:
998         kfree_skb(skb);
999         return false;
1000 }
1001 
1002 static const struct tlvtype_proc tlvprochopopt_lst[] = {
1003         {
1004                 .type   = IPV6_TLV_ROUTERALERT,
1005                 .func   = ipv6_hop_ra,
1006         },
1007         {
1008                 .type   = IPV6_TLV_JUMBO,
1009                 .func   = ipv6_hop_jumbo,
1010         },
1011         {
1012                 .type   = IPV6_TLV_CALIPSO,
1013                 .func   = ipv6_hop_calipso,
1014         },
1015         { -1, }
1016 };
1017 
1018 int ipv6_parse_hopopts(struct sk_buff *skb)
1019 {
1020         struct inet6_skb_parm *opt = IP6CB(skb);
1021         struct net *net = dev_net(skb->dev);
1022         int extlen;
1023 
1024         /*
1025          * skb_network_header(skb) is equal to skb->data, and
1026          * skb_network_header_len(skb) is always equal to
1027          * sizeof(struct ipv6hdr) by definition of
1028          * hop-by-hop options.
1029          */
1030         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
1031             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
1032                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
1033 fail_and_free:
1034                 kfree_skb(skb);
1035                 return -1;
1036         }
1037 
1038         extlen = (skb_transport_header(skb)[1] + 1) << 3;
1039         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
1040                 goto fail_and_free;
1041 
1042         opt->flags |= IP6SKB_HOPBYHOP;
1043         if (ip6_parse_tlv(tlvprochopopt_lst, skb,
1044                           init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
1045                 skb->transport_header += extlen;
1046                 opt = IP6CB(skb);
1047                 opt->nhoff = sizeof(struct ipv6hdr);
1048                 return 1;
1049         }
1050         return -1;
1051 }
1052 
1053 /*
1054  *      Creating outbound headers.
1055  *
1056  *      "build" functions work when skb is filled from head to tail (datagram)
1057  *      "push"  functions work when headers are added from tail to head (tcp)
1058  *
1059  *      In both cases we assume, that caller reserved enough room
1060  *      for headers.
1061  */
1062 
1063 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
1064                              struct ipv6_rt_hdr *opt,
1065                              struct in6_addr **addr_p, struct in6_addr *saddr)
1066 {
1067         struct rt0_hdr *phdr, *ihdr;
1068         int hops;
1069 
1070         ihdr = (struct rt0_hdr *) opt;
1071 
1072         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
1073         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
1074 
1075         hops = ihdr->rt_hdr.hdrlen >> 1;
1076 
1077         if (hops > 1)
1078                 memcpy(phdr->addr, ihdr->addr + 1,
1079                        (hops - 1) * sizeof(struct in6_addr));
1080 
1081         phdr->addr[hops - 1] = **addr_p;
1082         *addr_p = ihdr->addr;
1083 
1084         phdr->rt_hdr.nexthdr = *proto;
1085         *proto = NEXTHDR_ROUTING;
1086 }
1087 
1088 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
1089                              struct ipv6_rt_hdr *opt,
1090                              struct in6_addr **addr_p, struct in6_addr *saddr)
1091 {
1092         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
1093         int plen, hops;
1094 
1095         sr_ihdr = (struct ipv6_sr_hdr *)opt;
1096         plen = (sr_ihdr->hdrlen + 1) << 3;
1097 
1098         sr_phdr = skb_push(skb, plen);
1099         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
1100 
1101         hops = sr_ihdr->first_segment + 1;
1102         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
1103                (hops - 1) * sizeof(struct in6_addr));
1104 
1105         sr_phdr->segments[0] = **addr_p;
1106         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
1107 
1108         if (sr_ihdr->hdrlen > hops * 2) {
1109                 int tlvs_offset, tlvs_length;
1110 
1111                 tlvs_offset = (1 + hops * 2) << 3;
1112                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
1113                 memcpy((char *)sr_phdr + tlvs_offset,
1114                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
1115         }
1116 
1117 #ifdef CONFIG_IPV6_SEG6_HMAC
1118         if (sr_has_hmac(sr_phdr)) {
1119                 struct net *net = NULL;
1120 
1121                 if (skb->dev)
1122                         net = dev_net(skb->dev);
1123                 else if (skb->sk)
1124                         net = sock_net(skb->sk);
1125 
1126                 WARN_ON(!net);
1127 
1128                 if (net)
1129                         seg6_push_hmac(net, saddr, sr_phdr);
1130         }
1131 #endif
1132 
1133         sr_phdr->nexthdr = *proto;
1134         *proto = NEXTHDR_ROUTING;
1135 }
1136 
1137 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
1138                             struct ipv6_rt_hdr *opt,
1139                             struct in6_addr **addr_p, struct in6_addr *saddr)
1140 {
1141         switch (opt->type) {
1142         case IPV6_SRCRT_TYPE_0:
1143         case IPV6_SRCRT_STRICT:
1144         case IPV6_SRCRT_TYPE_2:
1145                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
1146                 break;
1147         case IPV6_SRCRT_TYPE_4:
1148                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
1149                 break;
1150         default:
1151                 break;
1152         }
1153 }
1154 
1155 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
1156 {
1157         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
1158 
1159         memcpy(h, opt, ipv6_optlen(opt));
1160         h->nexthdr = *proto;
1161         *proto = type;
1162 }
1163 
1164 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
1165                           u8 *proto,
1166                           struct in6_addr **daddr, struct in6_addr *saddr)
1167 {
1168         if (opt->srcrt) {
1169                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
1170                 /*
1171                  * IPV6_RTHDRDSTOPTS is ignored
1172                  * unless IPV6_RTHDR is set (RFC3542).
1173                  */
1174                 if (opt->dst0opt)
1175                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
1176         }
1177         if (opt->hopopt)
1178                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
1179 }
1180 
1181 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
1182 {
1183         if (opt->dst1opt)
1184                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
1185 }
1186 EXPORT_SYMBOL(ipv6_push_frag_opts);
1187 
1188 struct ipv6_txoptions *
1189 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
1190 {
1191         struct ipv6_txoptions *opt2;
1192 
1193         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1194         if (opt2) {
1195                 long dif = (char *)opt2 - (char *)opt;
1196                 memcpy(opt2, opt, opt->tot_len);
1197                 if (opt2->hopopt)
1198                         *((char **)&opt2->hopopt) += dif;
1199                 if (opt2->dst0opt)
1200                         *((char **)&opt2->dst0opt) += dif;
1201                 if (opt2->dst1opt)
1202                         *((char **)&opt2->dst1opt) += dif;
1203                 if (opt2->srcrt)
1204                         *((char **)&opt2->srcrt) += dif;
1205                 refcount_set(&opt2->refcnt, 1);
1206         }
1207         return opt2;
1208 }
1209 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1210 
1211 static void ipv6_renew_option(int renewtype,
1212                               struct ipv6_opt_hdr **dest,
1213                               struct ipv6_opt_hdr *old,
1214                               struct ipv6_opt_hdr *new,
1215                               int newtype, char **p)
1216 {
1217         struct ipv6_opt_hdr *src;
1218 
1219         src = (renewtype == newtype ? new : old);
1220         if (!src)
1221                 return;
1222 
1223         memcpy(*p, src, ipv6_optlen(src));
1224         *dest = (struct ipv6_opt_hdr *)*p;
1225         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1226 }
1227 
1228 /**
1229  * ipv6_renew_options - replace a specific ext hdr with a new one.
1230  *
1231  * @sk: sock from which to allocate memory
1232  * @opt: original options
1233  * @newtype: option type to replace in @opt
1234  * @newopt: new option of type @newtype to replace (user-mem)
1235  * @newoptlen: length of @newopt
1236  *
1237  * Returns a new set of options which is a copy of @opt with the
1238  * option type @newtype replaced with @newopt.
1239  *
1240  * @opt may be NULL, in which case a new set of options is returned
1241  * containing just @newopt.
1242  *
1243  * @newopt may be NULL, in which case the specified option type is
1244  * not copied into the new set of options.
1245  *
1246  * The new set of options is allocated from the socket option memory
1247  * buffer of @sk.
1248  */
1249 struct ipv6_txoptions *
1250 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1251                    int newtype, struct ipv6_opt_hdr *newopt)
1252 {
1253         int tot_len = 0;
1254         char *p;
1255         struct ipv6_txoptions *opt2;
1256 
1257         if (opt) {
1258                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1259                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1260                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1261                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1262                 if (newtype != IPV6_RTHDR && opt->srcrt)
1263                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1264                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1265                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1266         }
1267 
1268         if (newopt)
1269                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1270 
1271         if (!tot_len)
1272                 return NULL;
1273 
1274         tot_len += sizeof(*opt2);
1275         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1276         if (!opt2)
1277                 return ERR_PTR(-ENOBUFS);
1278 
1279         memset(opt2, 0, tot_len);
1280         refcount_set(&opt2->refcnt, 1);
1281         opt2->tot_len = tot_len;
1282         p = (char *)(opt2 + 1);
1283 
1284         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1285                           (opt ? opt->hopopt : NULL),
1286                           newopt, newtype, &p);
1287         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1288                           (opt ? opt->dst0opt : NULL),
1289                           newopt, newtype, &p);
1290         ipv6_renew_option(IPV6_RTHDR,
1291                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1292                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1293                           newopt, newtype, &p);
1294         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1295                           (opt ? opt->dst1opt : NULL),
1296                           newopt, newtype, &p);
1297 
1298         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1299                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1300                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1301         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1302 
1303         return opt2;
1304 }
1305 
1306 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1307                                           struct ipv6_txoptions *opt)
1308 {
1309         /*
1310          * ignore the dest before srcrt unless srcrt is being included.
1311          * --yoshfuji
1312          */
1313         if (opt && opt->dst0opt && !opt->srcrt) {
1314                 if (opt_space != opt) {
1315                         memcpy(opt_space, opt, sizeof(*opt_space));
1316                         opt = opt_space;
1317                 }
1318                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1319                 opt->dst0opt = NULL;
1320         }
1321 
1322         return opt;
1323 }
1324 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
1325 
1326 /**
1327  * fl6_update_dst - update flowi destination address with info given
1328  *                  by srcrt option, if any.
1329  *
1330  * @fl6: flowi6 for which daddr is to be updated
1331  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1332  * @orig: copy of original daddr address if modified
1333  *
1334  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1335  * and initial value of fl6->daddr set in orig
1336  */
1337 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1338                                 const struct ipv6_txoptions *opt,
1339                                 struct in6_addr *orig)
1340 {
1341         if (!opt || !opt->srcrt)
1342                 return NULL;
1343 
1344         *orig = fl6->daddr;
1345 
1346         switch (opt->srcrt->type) {
1347         case IPV6_SRCRT_TYPE_0:
1348         case IPV6_SRCRT_STRICT:
1349         case IPV6_SRCRT_TYPE_2:
1350                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1351                 break;
1352         case IPV6_SRCRT_TYPE_4:
1353         {
1354                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1355 
1356                 fl6->daddr = srh->segments[srh->segments_left];
1357                 break;
1358         }
1359         default:
1360                 return NULL;
1361         }
1362 
1363         return orig;
1364 }
1365 EXPORT_SYMBOL_GPL(fl6_update_dst);
1366 

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