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TOMOYO Linux Cross Reference
Linux/net/ipv6/exthdrs.c

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  1 /*
  2  *      Extension Header handling for IPv6
  3  *      Linux INET6 implementation
  4  *
  5  *      Authors:
  6  *      Pedro Roque             <roque@di.fc.ul.pt>
  7  *      Andi Kleen              <ak@muc.de>
  8  *      Alexey Kuznetsov        <kuznet@ms2.inr.ac.ru>
  9  *
 10  *      This program is free software; you can redistribute it and/or
 11  *      modify it under the terms of the GNU General Public License
 12  *      as published by the Free Software Foundation; either version
 13  *      2 of the License, or (at your option) any later version.
 14  */
 15 
 16 /* Changes:
 17  *      yoshfuji                : ensure not to overrun while parsing
 18  *                                tlv options.
 19  *      Mitsuru KANDA @USAGI and: Remove ipv6_parse_exthdrs().
 20  *      YOSHIFUJI Hideaki @USAGI  Register inbound extension header
 21  *                                handlers as inet6_protocol{}.
 22  */
 23 
 24 #include <linux/errno.h>
 25 #include <linux/types.h>
 26 #include <linux/socket.h>
 27 #include <linux/sockios.h>
 28 #include <linux/net.h>
 29 #include <linux/netdevice.h>
 30 #include <linux/in6.h>
 31 #include <linux/icmpv6.h>
 32 #include <linux/slab.h>
 33 #include <linux/export.h>
 34 
 35 #include <net/dst.h>
 36 #include <net/sock.h>
 37 #include <net/snmp.h>
 38 
 39 #include <net/ipv6.h>
 40 #include <net/protocol.h>
 41 #include <net/transp_v6.h>
 42 #include <net/rawv6.h>
 43 #include <net/ndisc.h>
 44 #include <net/ip6_route.h>
 45 #include <net/addrconf.h>
 46 #include <net/calipso.h>
 47 #if IS_ENABLED(CONFIG_IPV6_MIP6)
 48 #include <net/xfrm.h>
 49 #endif
 50 #include <linux/seg6.h>
 51 #include <net/seg6.h>
 52 #ifdef CONFIG_IPV6_SEG6_HMAC
 53 #include <net/seg6_hmac.h>
 54 #endif
 55 
 56 #include <linux/uaccess.h>
 57 
 58 /*
 59  *      Parsing tlv encoded headers.
 60  *
 61  *      Parsing function "func" returns true, if parsing succeed
 62  *      and false, if it failed.
 63  *      It MUST NOT touch skb->h.
 64  */
 65 
 66 struct tlvtype_proc {
 67         int     type;
 68         bool    (*func)(struct sk_buff *skb, int offset);
 69 };
 70 
 71 /*********************
 72   Generic functions
 73  *********************/
 74 
 75 /* An unknown option is detected, decide what to do */
 76 
 77 static bool ip6_tlvopt_unknown(struct sk_buff *skb, int optoff,
 78                                bool disallow_unknowns)
 79 {
 80         if (disallow_unknowns) {
 81                 /* If unknown TLVs are disallowed by configuration
 82                  * then always silently drop packet. Note this also
 83                  * means no ICMP parameter problem is sent which
 84                  * could be a good property to mitigate a reflection DOS
 85                  * attack.
 86                  */
 87 
 88                 goto drop;
 89         }
 90 
 91         switch ((skb_network_header(skb)[optoff] & 0xC0) >> 6) {
 92         case 0: /* ignore */
 93                 return true;
 94 
 95         case 1: /* drop packet */
 96                 break;
 97 
 98         case 3: /* Send ICMP if not a multicast address and drop packet */
 99                 /* Actually, it is redundant check. icmp_send
100                    will recheck in any case.
101                  */
102                 if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr))
103                         break;
104                 /* fall through */
105         case 2: /* send ICMP PARM PROB regardless and drop packet */
106                 icmpv6_param_prob(skb, ICMPV6_UNK_OPTION, optoff);
107                 return false;
108         }
109 
110 drop:
111         kfree_skb(skb);
112         return false;
113 }
114 
115 /* Parse tlv encoded option header (hop-by-hop or destination) */
116 
117 static bool ip6_parse_tlv(const struct tlvtype_proc *procs,
118                           struct sk_buff *skb,
119                           int max_count)
120 {
121         int len = (skb_transport_header(skb)[1] + 1) << 3;
122         const unsigned char *nh = skb_network_header(skb);
123         int off = skb_network_header_len(skb);
124         const struct tlvtype_proc *curr;
125         bool disallow_unknowns = false;
126         int tlv_count = 0;
127         int padlen = 0;
128 
129         if (unlikely(max_count < 0)) {
130                 disallow_unknowns = true;
131                 max_count = -max_count;
132         }
133 
134         if (skb_transport_offset(skb) + len > skb_headlen(skb))
135                 goto bad;
136 
137         off += 2;
138         len -= 2;
139 
140         while (len > 0) {
141                 int optlen = nh[off + 1] + 2;
142                 int i;
143 
144                 switch (nh[off]) {
145                 case IPV6_TLV_PAD1:
146                         optlen = 1;
147                         padlen++;
148                         if (padlen > 7)
149                                 goto bad;
150                         break;
151 
152                 case IPV6_TLV_PADN:
153                         /* RFC 2460 states that the purpose of PadN is
154                          * to align the containing header to multiples
155                          * of 8. 7 is therefore the highest valid value.
156                          * See also RFC 4942, Section 2.1.9.5.
157                          */
158                         padlen += optlen;
159                         if (padlen > 7)
160                                 goto bad;
161                         /* RFC 4942 recommends receiving hosts to
162                          * actively check PadN payload to contain
163                          * only zeroes.
164                          */
165                         for (i = 2; i < optlen; i++) {
166                                 if (nh[off + i] != 0)
167                                         goto bad;
168                         }
169                         break;
170 
171                 default: /* Other TLV code so scan list */
172                         if (optlen > len)
173                                 goto bad;
174 
175                         tlv_count++;
176                         if (tlv_count > max_count)
177                                 goto bad;
178 
179                         for (curr = procs; curr->type >= 0; curr++) {
180                                 if (curr->type == nh[off]) {
181                                         /* type specific length/alignment
182                                            checks will be performed in the
183                                            func(). */
184                                         if (curr->func(skb, off) == false)
185                                                 return false;
186                                         break;
187                                 }
188                         }
189                         if (curr->type < 0 &&
190                             !ip6_tlvopt_unknown(skb, off, disallow_unknowns))
191                                 return false;
192 
193                         padlen = 0;
194                         break;
195                 }
196                 off += optlen;
197                 len -= optlen;
198         }
199 
200         if (len == 0)
201                 return true;
202 bad:
203         kfree_skb(skb);
204         return false;
205 }
206 
207 /*****************************
208   Destination options header.
209  *****************************/
210 
211 #if IS_ENABLED(CONFIG_IPV6_MIP6)
212 static bool ipv6_dest_hao(struct sk_buff *skb, int optoff)
213 {
214         struct ipv6_destopt_hao *hao;
215         struct inet6_skb_parm *opt = IP6CB(skb);
216         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
217         int ret;
218 
219         if (opt->dsthao) {
220                 net_dbg_ratelimited("hao duplicated\n");
221                 goto discard;
222         }
223         opt->dsthao = opt->dst1;
224         opt->dst1 = 0;
225 
226         hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) + optoff);
227 
228         if (hao->length != 16) {
229                 net_dbg_ratelimited("hao invalid option length = %d\n",
230                                     hao->length);
231                 goto discard;
232         }
233 
234         if (!(ipv6_addr_type(&hao->addr) & IPV6_ADDR_UNICAST)) {
235                 net_dbg_ratelimited("hao is not an unicast addr: %pI6\n",
236                                     &hao->addr);
237                 goto discard;
238         }
239 
240         ret = xfrm6_input_addr(skb, (xfrm_address_t *)&ipv6h->daddr,
241                                (xfrm_address_t *)&hao->addr, IPPROTO_DSTOPTS);
242         if (unlikely(ret < 0))
243                 goto discard;
244 
245         if (skb_cloned(skb)) {
246                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
247                         goto discard;
248 
249                 /* update all variable using below by copied skbuff */
250                 hao = (struct ipv6_destopt_hao *)(skb_network_header(skb) +
251                                                   optoff);
252                 ipv6h = ipv6_hdr(skb);
253         }
254 
255         if (skb->ip_summed == CHECKSUM_COMPLETE)
256                 skb->ip_summed = CHECKSUM_NONE;
257 
258         swap(ipv6h->saddr, hao->addr);
259 
260         if (skb->tstamp == 0)
261                 __net_timestamp(skb);
262 
263         return true;
264 
265  discard:
266         kfree_skb(skb);
267         return false;
268 }
269 #endif
270 
271 static const struct tlvtype_proc tlvprocdestopt_lst[] = {
272 #if IS_ENABLED(CONFIG_IPV6_MIP6)
273         {
274                 .type   = IPV6_TLV_HAO,
275                 .func   = ipv6_dest_hao,
276         },
277 #endif
278         {-1,                    NULL}
279 };
280 
281 static int ipv6_destopt_rcv(struct sk_buff *skb)
282 {
283         struct inet6_skb_parm *opt = IP6CB(skb);
284 #if IS_ENABLED(CONFIG_IPV6_MIP6)
285         __u16 dstbuf;
286 #endif
287         struct dst_entry *dst = skb_dst(skb);
288         struct net *net = dev_net(skb->dev);
289         int extlen;
290 
291         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
292             !pskb_may_pull(skb, (skb_transport_offset(skb) +
293                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
294                 __IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst),
295                                 IPSTATS_MIB_INHDRERRORS);
296 fail_and_free:
297                 kfree_skb(skb);
298                 return -1;
299         }
300 
301         extlen = (skb_transport_header(skb)[1] + 1) << 3;
302         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
303                 goto fail_and_free;
304 
305         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
306 #if IS_ENABLED(CONFIG_IPV6_MIP6)
307         dstbuf = opt->dst1;
308 #endif
309 
310         if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
311                           init_net.ipv6.sysctl.max_dst_opts_cnt)) {
312                 skb->transport_header += extlen;
313                 opt = IP6CB(skb);
314 #if IS_ENABLED(CONFIG_IPV6_MIP6)
315                 opt->nhoff = dstbuf;
316 #else
317                 opt->nhoff = opt->dst1;
318 #endif
319                 return 1;
320         }
321 
322         __IP6_INC_STATS(dev_net(dst->dev),
323                         ip6_dst_idev(dst), IPSTATS_MIB_INHDRERRORS);
324         return -1;
325 }
326 
327 static void seg6_update_csum(struct sk_buff *skb)
328 {
329         struct ipv6_sr_hdr *hdr;
330         struct in6_addr *addr;
331         __be32 from, to;
332 
333         /* srh is at transport offset and seg_left is already decremented
334          * but daddr is not yet updated with next segment
335          */
336 
337         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
338         addr = hdr->segments + hdr->segments_left;
339 
340         hdr->segments_left++;
341         from = *(__be32 *)hdr;
342 
343         hdr->segments_left--;
344         to = *(__be32 *)hdr;
345 
346         /* update skb csum with diff resulting from seg_left decrement */
347 
348         update_csum_diff4(skb, from, to);
349 
350         /* compute csum diff between current and next segment and update */
351 
352         update_csum_diff16(skb, (__be32 *)(&ipv6_hdr(skb)->daddr),
353                            (__be32 *)addr);
354 }
355 
356 static int ipv6_srh_rcv(struct sk_buff *skb)
357 {
358         struct inet6_skb_parm *opt = IP6CB(skb);
359         struct net *net = dev_net(skb->dev);
360         struct ipv6_sr_hdr *hdr;
361         struct inet6_dev *idev;
362         struct in6_addr *addr;
363         int accept_seg6;
364 
365         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
366 
367         idev = __in6_dev_get(skb->dev);
368 
369         accept_seg6 = net->ipv6.devconf_all->seg6_enabled;
370         if (accept_seg6 > idev->cnf.seg6_enabled)
371                 accept_seg6 = idev->cnf.seg6_enabled;
372 
373         if (!accept_seg6) {
374                 kfree_skb(skb);
375                 return -1;
376         }
377 
378 #ifdef CONFIG_IPV6_SEG6_HMAC
379         if (!seg6_hmac_validate_skb(skb)) {
380                 kfree_skb(skb);
381                 return -1;
382         }
383 #endif
384 
385 looped_back:
386         if (hdr->segments_left == 0) {
387                 if (hdr->nexthdr == NEXTHDR_IPV6) {
388                         int offset = (hdr->hdrlen + 1) << 3;
389 
390                         skb_postpull_rcsum(skb, skb_network_header(skb),
391                                            skb_network_header_len(skb));
392 
393                         if (!pskb_pull(skb, offset)) {
394                                 kfree_skb(skb);
395                                 return -1;
396                         }
397                         skb_postpull_rcsum(skb, skb_transport_header(skb),
398                                            offset);
399 
400                         skb_reset_network_header(skb);
401                         skb_reset_transport_header(skb);
402                         skb->encapsulation = 0;
403 
404                         __skb_tunnel_rx(skb, skb->dev, net);
405 
406                         netif_rx(skb);
407                         return -1;
408                 }
409 
410                 opt->srcrt = skb_network_header_len(skb);
411                 opt->lastopt = opt->srcrt;
412                 skb->transport_header += (hdr->hdrlen + 1) << 3;
413                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
414 
415                 return 1;
416         }
417 
418         if (hdr->segments_left >= (hdr->hdrlen >> 1)) {
419                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
420                                 IPSTATS_MIB_INHDRERRORS);
421                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
422                                   ((&hdr->segments_left) -
423                                    skb_network_header(skb)));
424                 return -1;
425         }
426 
427         if (skb_cloned(skb)) {
428                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
429                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
430                                         IPSTATS_MIB_OUTDISCARDS);
431                         kfree_skb(skb);
432                         return -1;
433                 }
434         }
435 
436         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
437 
438         hdr->segments_left--;
439         addr = hdr->segments + hdr->segments_left;
440 
441         skb_push(skb, sizeof(struct ipv6hdr));
442 
443         if (skb->ip_summed == CHECKSUM_COMPLETE)
444                 seg6_update_csum(skb);
445 
446         ipv6_hdr(skb)->daddr = *addr;
447 
448         skb_dst_drop(skb);
449 
450         ip6_route_input(skb);
451 
452         if (skb_dst(skb)->error) {
453                 dst_input(skb);
454                 return -1;
455         }
456 
457         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
458                 if (ipv6_hdr(skb)->hop_limit <= 1) {
459                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
460                                         IPSTATS_MIB_INHDRERRORS);
461                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
462                                     ICMPV6_EXC_HOPLIMIT, 0);
463                         kfree_skb(skb);
464                         return -1;
465                 }
466                 ipv6_hdr(skb)->hop_limit--;
467 
468                 skb_pull(skb, sizeof(struct ipv6hdr));
469                 goto looped_back;
470         }
471 
472         dst_input(skb);
473 
474         return -1;
475 }
476 
477 /********************************
478   Routing header.
479  ********************************/
480 
481 /* called with rcu_read_lock() */
482 static int ipv6_rthdr_rcv(struct sk_buff *skb)
483 {
484         struct inet6_skb_parm *opt = IP6CB(skb);
485         struct in6_addr *addr = NULL;
486         struct in6_addr daddr;
487         struct inet6_dev *idev;
488         int n, i;
489         struct ipv6_rt_hdr *hdr;
490         struct rt0_hdr *rthdr;
491         struct net *net = dev_net(skb->dev);
492         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
493 
494         idev = __in6_dev_get(skb->dev);
495         if (idev && accept_source_route > idev->cnf.accept_source_route)
496                 accept_source_route = idev->cnf.accept_source_route;
497 
498         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
499             !pskb_may_pull(skb, (skb_transport_offset(skb) +
500                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
501                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
502                                 IPSTATS_MIB_INHDRERRORS);
503                 kfree_skb(skb);
504                 return -1;
505         }
506 
507         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
508 
509         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
510             skb->pkt_type != PACKET_HOST) {
511                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
512                                 IPSTATS_MIB_INADDRERRORS);
513                 kfree_skb(skb);
514                 return -1;
515         }
516 
517         /* segment routing */
518         if (hdr->type == IPV6_SRCRT_TYPE_4)
519                 return ipv6_srh_rcv(skb);
520 
521 looped_back:
522         if (hdr->segments_left == 0) {
523                 switch (hdr->type) {
524 #if IS_ENABLED(CONFIG_IPV6_MIP6)
525                 case IPV6_SRCRT_TYPE_2:
526                         /* Silently discard type 2 header unless it was
527                          * processed by own
528                          */
529                         if (!addr) {
530                                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
531                                                 IPSTATS_MIB_INADDRERRORS);
532                                 kfree_skb(skb);
533                                 return -1;
534                         }
535                         break;
536 #endif
537                 default:
538                         break;
539                 }
540 
541                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
542                 skb->transport_header += (hdr->hdrlen + 1) << 3;
543                 opt->dst0 = opt->dst1;
544                 opt->dst1 = 0;
545                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
546                 return 1;
547         }
548 
549         switch (hdr->type) {
550 #if IS_ENABLED(CONFIG_IPV6_MIP6)
551         case IPV6_SRCRT_TYPE_2:
552                 if (accept_source_route < 0)
553                         goto unknown_rh;
554                 /* Silently discard invalid RTH type 2 */
555                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
556                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
557                                         IPSTATS_MIB_INHDRERRORS);
558                         kfree_skb(skb);
559                         return -1;
560                 }
561                 break;
562 #endif
563         default:
564                 goto unknown_rh;
565         }
566 
567         /*
568          *      This is the routing header forwarding algorithm from
569          *      RFC 2460, page 16.
570          */
571 
572         n = hdr->hdrlen >> 1;
573 
574         if (hdr->segments_left > n) {
575                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
576                                 IPSTATS_MIB_INHDRERRORS);
577                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
578                                   ((&hdr->segments_left) -
579                                    skb_network_header(skb)));
580                 return -1;
581         }
582 
583         /* We are about to mangle packet header. Be careful!
584            Do not damage packets queued somewhere.
585          */
586         if (skb_cloned(skb)) {
587                 /* the copy is a forwarded packet */
588                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
589                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
590                                         IPSTATS_MIB_OUTDISCARDS);
591                         kfree_skb(skb);
592                         return -1;
593                 }
594                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
595         }
596 
597         if (skb->ip_summed == CHECKSUM_COMPLETE)
598                 skb->ip_summed = CHECKSUM_NONE;
599 
600         i = n - --hdr->segments_left;
601 
602         rthdr = (struct rt0_hdr *) hdr;
603         addr = rthdr->addr;
604         addr += i - 1;
605 
606         switch (hdr->type) {
607 #if IS_ENABLED(CONFIG_IPV6_MIP6)
608         case IPV6_SRCRT_TYPE_2:
609                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
610                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
611                                      IPPROTO_ROUTING) < 0) {
612                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
613                                         IPSTATS_MIB_INADDRERRORS);
614                         kfree_skb(skb);
615                         return -1;
616                 }
617                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
618                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
619                                         IPSTATS_MIB_INADDRERRORS);
620                         kfree_skb(skb);
621                         return -1;
622                 }
623                 break;
624 #endif
625         default:
626                 break;
627         }
628 
629         if (ipv6_addr_is_multicast(addr)) {
630                 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
631                                 IPSTATS_MIB_INADDRERRORS);
632                 kfree_skb(skb);
633                 return -1;
634         }
635 
636         daddr = *addr;
637         *addr = ipv6_hdr(skb)->daddr;
638         ipv6_hdr(skb)->daddr = daddr;
639 
640         skb_dst_drop(skb);
641         ip6_route_input(skb);
642         if (skb_dst(skb)->error) {
643                 skb_push(skb, skb->data - skb_network_header(skb));
644                 dst_input(skb);
645                 return -1;
646         }
647 
648         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
649                 if (ipv6_hdr(skb)->hop_limit <= 1) {
650                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
651                                         IPSTATS_MIB_INHDRERRORS);
652                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
653                                     0);
654                         kfree_skb(skb);
655                         return -1;
656                 }
657                 ipv6_hdr(skb)->hop_limit--;
658                 goto looped_back;
659         }
660 
661         skb_push(skb, skb->data - skb_network_header(skb));
662         dst_input(skb);
663         return -1;
664 
665 unknown_rh:
666         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INHDRERRORS);
667         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
668                           (&hdr->type) - skb_network_header(skb));
669         return -1;
670 }
671 
672 static const struct inet6_protocol rthdr_protocol = {
673         .handler        =       ipv6_rthdr_rcv,
674         .flags          =       INET6_PROTO_NOPOLICY,
675 };
676 
677 static const struct inet6_protocol destopt_protocol = {
678         .handler        =       ipv6_destopt_rcv,
679         .flags          =       INET6_PROTO_NOPOLICY,
680 };
681 
682 static const struct inet6_protocol nodata_protocol = {
683         .handler        =       dst_discard,
684         .flags          =       INET6_PROTO_NOPOLICY,
685 };
686 
687 int __init ipv6_exthdrs_init(void)
688 {
689         int ret;
690 
691         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
692         if (ret)
693                 goto out;
694 
695         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
696         if (ret)
697                 goto out_rthdr;
698 
699         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
700         if (ret)
701                 goto out_destopt;
702 
703 out:
704         return ret;
705 out_destopt:
706         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
707 out_rthdr:
708         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
709         goto out;
710 };
711 
712 void ipv6_exthdrs_exit(void)
713 {
714         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
715         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
716         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
717 }
718 
719 /**********************************
720   Hop-by-hop options.
721  **********************************/
722 
723 /*
724  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
725  */
726 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
727 {
728         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
729 }
730 
731 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
732 {
733         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
734 }
735 
736 /* Router Alert as of RFC 2711 */
737 
738 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
739 {
740         const unsigned char *nh = skb_network_header(skb);
741 
742         if (nh[optoff + 1] == 2) {
743                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
744                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
745                 return true;
746         }
747         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
748                             nh[optoff + 1]);
749         kfree_skb(skb);
750         return false;
751 }
752 
753 /* Jumbo payload */
754 
755 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
756 {
757         const unsigned char *nh = skb_network_header(skb);
758         struct net *net = ipv6_skb_net(skb);
759         u32 pkt_len;
760 
761         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
762                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
763                                     nh[optoff+1]);
764                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
765                                 IPSTATS_MIB_INHDRERRORS);
766                 goto drop;
767         }
768 
769         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
770         if (pkt_len <= IPV6_MAXPLEN) {
771                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
772                                 IPSTATS_MIB_INHDRERRORS);
773                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
774                 return false;
775         }
776         if (ipv6_hdr(skb)->payload_len) {
777                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
778                                 IPSTATS_MIB_INHDRERRORS);
779                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
780                 return false;
781         }
782 
783         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
784                 __IP6_INC_STATS(net, ipv6_skb_idev(skb),
785                                 IPSTATS_MIB_INTRUNCATEDPKTS);
786                 goto drop;
787         }
788 
789         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
790                 goto drop;
791 
792         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
793         return true;
794 
795 drop:
796         kfree_skb(skb);
797         return false;
798 }
799 
800 /* CALIPSO RFC 5570 */
801 
802 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
803 {
804         const unsigned char *nh = skb_network_header(skb);
805 
806         if (nh[optoff + 1] < 8)
807                 goto drop;
808 
809         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
810                 goto drop;
811 
812         if (!calipso_validate(skb, nh + optoff))
813                 goto drop;
814 
815         return true;
816 
817 drop:
818         kfree_skb(skb);
819         return false;
820 }
821 
822 static const struct tlvtype_proc tlvprochopopt_lst[] = {
823         {
824                 .type   = IPV6_TLV_ROUTERALERT,
825                 .func   = ipv6_hop_ra,
826         },
827         {
828                 .type   = IPV6_TLV_JUMBO,
829                 .func   = ipv6_hop_jumbo,
830         },
831         {
832                 .type   = IPV6_TLV_CALIPSO,
833                 .func   = ipv6_hop_calipso,
834         },
835         { -1, }
836 };
837 
838 int ipv6_parse_hopopts(struct sk_buff *skb)
839 {
840         struct inet6_skb_parm *opt = IP6CB(skb);
841         struct net *net = dev_net(skb->dev);
842         int extlen;
843 
844         /*
845          * skb_network_header(skb) is equal to skb->data, and
846          * skb_network_header_len(skb) is always equal to
847          * sizeof(struct ipv6hdr) by definition of
848          * hop-by-hop options.
849          */
850         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
851             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
852                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
853 fail_and_free:
854                 kfree_skb(skb);
855                 return -1;
856         }
857 
858         extlen = (skb_transport_header(skb)[1] + 1) << 3;
859         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
860                 goto fail_and_free;
861 
862         opt->flags |= IP6SKB_HOPBYHOP;
863         if (ip6_parse_tlv(tlvprochopopt_lst, skb,
864                           init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
865                 skb->transport_header += extlen;
866                 opt = IP6CB(skb);
867                 opt->nhoff = sizeof(struct ipv6hdr);
868                 return 1;
869         }
870         return -1;
871 }
872 
873 /*
874  *      Creating outbound headers.
875  *
876  *      "build" functions work when skb is filled from head to tail (datagram)
877  *      "push"  functions work when headers are added from tail to head (tcp)
878  *
879  *      In both cases we assume, that caller reserved enough room
880  *      for headers.
881  */
882 
883 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
884                              struct ipv6_rt_hdr *opt,
885                              struct in6_addr **addr_p, struct in6_addr *saddr)
886 {
887         struct rt0_hdr *phdr, *ihdr;
888         int hops;
889 
890         ihdr = (struct rt0_hdr *) opt;
891 
892         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
893         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
894 
895         hops = ihdr->rt_hdr.hdrlen >> 1;
896 
897         if (hops > 1)
898                 memcpy(phdr->addr, ihdr->addr + 1,
899                        (hops - 1) * sizeof(struct in6_addr));
900 
901         phdr->addr[hops - 1] = **addr_p;
902         *addr_p = ihdr->addr;
903 
904         phdr->rt_hdr.nexthdr = *proto;
905         *proto = NEXTHDR_ROUTING;
906 }
907 
908 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
909                              struct ipv6_rt_hdr *opt,
910                              struct in6_addr **addr_p, struct in6_addr *saddr)
911 {
912         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
913         int plen, hops;
914 
915         sr_ihdr = (struct ipv6_sr_hdr *)opt;
916         plen = (sr_ihdr->hdrlen + 1) << 3;
917 
918         sr_phdr = skb_push(skb, plen);
919         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
920 
921         hops = sr_ihdr->first_segment + 1;
922         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
923                (hops - 1) * sizeof(struct in6_addr));
924 
925         sr_phdr->segments[0] = **addr_p;
926         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
927 
928 #ifdef CONFIG_IPV6_SEG6_HMAC
929         if (sr_has_hmac(sr_phdr)) {
930                 struct net *net = NULL;
931 
932                 if (skb->dev)
933                         net = dev_net(skb->dev);
934                 else if (skb->sk)
935                         net = sock_net(skb->sk);
936 
937                 WARN_ON(!net);
938 
939                 if (net)
940                         seg6_push_hmac(net, saddr, sr_phdr);
941         }
942 #endif
943 
944         sr_phdr->nexthdr = *proto;
945         *proto = NEXTHDR_ROUTING;
946 }
947 
948 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
949                             struct ipv6_rt_hdr *opt,
950                             struct in6_addr **addr_p, struct in6_addr *saddr)
951 {
952         switch (opt->type) {
953         case IPV6_SRCRT_TYPE_0:
954         case IPV6_SRCRT_STRICT:
955         case IPV6_SRCRT_TYPE_2:
956                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
957                 break;
958         case IPV6_SRCRT_TYPE_4:
959                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
960                 break;
961         default:
962                 break;
963         }
964 }
965 
966 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
967 {
968         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
969 
970         memcpy(h, opt, ipv6_optlen(opt));
971         h->nexthdr = *proto;
972         *proto = type;
973 }
974 
975 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
976                           u8 *proto,
977                           struct in6_addr **daddr, struct in6_addr *saddr)
978 {
979         if (opt->srcrt) {
980                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
981                 /*
982                  * IPV6_RTHDRDSTOPTS is ignored
983                  * unless IPV6_RTHDR is set (RFC3542).
984                  */
985                 if (opt->dst0opt)
986                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
987         }
988         if (opt->hopopt)
989                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
990 }
991 
992 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
993 {
994         if (opt->dst1opt)
995                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
996 }
997 EXPORT_SYMBOL(ipv6_push_frag_opts);
998 
999 struct ipv6_txoptions *
1000 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
1001 {
1002         struct ipv6_txoptions *opt2;
1003 
1004         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1005         if (opt2) {
1006                 long dif = (char *)opt2 - (char *)opt;
1007                 memcpy(opt2, opt, opt->tot_len);
1008                 if (opt2->hopopt)
1009                         *((char **)&opt2->hopopt) += dif;
1010                 if (opt2->dst0opt)
1011                         *((char **)&opt2->dst0opt) += dif;
1012                 if (opt2->dst1opt)
1013                         *((char **)&opt2->dst1opt) += dif;
1014                 if (opt2->srcrt)
1015                         *((char **)&opt2->srcrt) += dif;
1016                 refcount_set(&opt2->refcnt, 1);
1017         }
1018         return opt2;
1019 }
1020 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1021 
1022 static int ipv6_renew_option(void *ohdr,
1023                              struct ipv6_opt_hdr __user *newopt, int newoptlen,
1024                              int inherit,
1025                              struct ipv6_opt_hdr **hdr,
1026                              char **p)
1027 {
1028         if (inherit) {
1029                 if (ohdr) {
1030                         memcpy(*p, ohdr, ipv6_optlen((struct ipv6_opt_hdr *)ohdr));
1031                         *hdr = (struct ipv6_opt_hdr *)*p;
1032                         *p += CMSG_ALIGN(ipv6_optlen(*hdr));
1033                 }
1034         } else {
1035                 if (newopt) {
1036                         if (copy_from_user(*p, newopt, newoptlen))
1037                                 return -EFAULT;
1038                         *hdr = (struct ipv6_opt_hdr *)*p;
1039                         if (ipv6_optlen(*hdr) > newoptlen)
1040                                 return -EINVAL;
1041                         *p += CMSG_ALIGN(newoptlen);
1042                 }
1043         }
1044         return 0;
1045 }
1046 
1047 /**
1048  * ipv6_renew_options - replace a specific ext hdr with a new one.
1049  *
1050  * @sk: sock from which to allocate memory
1051  * @opt: original options
1052  * @newtype: option type to replace in @opt
1053  * @newopt: new option of type @newtype to replace (user-mem)
1054  * @newoptlen: length of @newopt
1055  *
1056  * Returns a new set of options which is a copy of @opt with the
1057  * option type @newtype replaced with @newopt.
1058  *
1059  * @opt may be NULL, in which case a new set of options is returned
1060  * containing just @newopt.
1061  *
1062  * @newopt may be NULL, in which case the specified option type is
1063  * not copied into the new set of options.
1064  *
1065  * The new set of options is allocated from the socket option memory
1066  * buffer of @sk.
1067  */
1068 struct ipv6_txoptions *
1069 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1070                    int newtype,
1071                    struct ipv6_opt_hdr __user *newopt, int newoptlen)
1072 {
1073         int tot_len = 0;
1074         char *p;
1075         struct ipv6_txoptions *opt2;
1076         int err;
1077 
1078         if (opt) {
1079                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1080                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1081                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1082                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1083                 if (newtype != IPV6_RTHDR && opt->srcrt)
1084                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1085                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1086                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1087         }
1088 
1089         if (newopt && newoptlen)
1090                 tot_len += CMSG_ALIGN(newoptlen);
1091 
1092         if (!tot_len)
1093                 return NULL;
1094 
1095         tot_len += sizeof(*opt2);
1096         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1097         if (!opt2)
1098                 return ERR_PTR(-ENOBUFS);
1099 
1100         memset(opt2, 0, tot_len);
1101         refcount_set(&opt2->refcnt, 1);
1102         opt2->tot_len = tot_len;
1103         p = (char *)(opt2 + 1);
1104 
1105         err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
1106                                 newtype != IPV6_HOPOPTS,
1107                                 &opt2->hopopt, &p);
1108         if (err)
1109                 goto out;
1110 
1111         err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
1112                                 newtype != IPV6_RTHDRDSTOPTS,
1113                                 &opt2->dst0opt, &p);
1114         if (err)
1115                 goto out;
1116 
1117         err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
1118                                 newtype != IPV6_RTHDR,
1119                                 (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
1120         if (err)
1121                 goto out;
1122 
1123         err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
1124                                 newtype != IPV6_DSTOPTS,
1125                                 &opt2->dst1opt, &p);
1126         if (err)
1127                 goto out;
1128 
1129         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1130                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1131                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1132         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1133 
1134         return opt2;
1135 out:
1136         sock_kfree_s(sk, opt2, opt2->tot_len);
1137         return ERR_PTR(err);
1138 }
1139 
1140 /**
1141  * ipv6_renew_options_kern - replace a specific ext hdr with a new one.
1142  *
1143  * @sk: sock from which to allocate memory
1144  * @opt: original options
1145  * @newtype: option type to replace in @opt
1146  * @newopt: new option of type @newtype to replace (kernel-mem)
1147  * @newoptlen: length of @newopt
1148  *
1149  * See ipv6_renew_options().  The difference is that @newopt is
1150  * kernel memory, rather than user memory.
1151  */
1152 struct ipv6_txoptions *
1153 ipv6_renew_options_kern(struct sock *sk, struct ipv6_txoptions *opt,
1154                         int newtype, struct ipv6_opt_hdr *newopt,
1155                         int newoptlen)
1156 {
1157         struct ipv6_txoptions *ret_val;
1158         const mm_segment_t old_fs = get_fs();
1159 
1160         set_fs(KERNEL_DS);
1161         ret_val = ipv6_renew_options(sk, opt, newtype,
1162                                      (struct ipv6_opt_hdr __user *)newopt,
1163                                      newoptlen);
1164         set_fs(old_fs);
1165         return ret_val;
1166 }
1167 
1168 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1169                                           struct ipv6_txoptions *opt)
1170 {
1171         /*
1172          * ignore the dest before srcrt unless srcrt is being included.
1173          * --yoshfuji
1174          */
1175         if (opt && opt->dst0opt && !opt->srcrt) {
1176                 if (opt_space != opt) {
1177                         memcpy(opt_space, opt, sizeof(*opt_space));
1178                         opt = opt_space;
1179                 }
1180                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1181                 opt->dst0opt = NULL;
1182         }
1183 
1184         return opt;
1185 }
1186 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
1187 
1188 /**
1189  * fl6_update_dst - update flowi destination address with info given
1190  *                  by srcrt option, if any.
1191  *
1192  * @fl6: flowi6 for which daddr is to be updated
1193  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1194  * @orig: copy of original daddr address if modified
1195  *
1196  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1197  * and initial value of fl6->daddr set in orig
1198  */
1199 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1200                                 const struct ipv6_txoptions *opt,
1201                                 struct in6_addr *orig)
1202 {
1203         if (!opt || !opt->srcrt)
1204                 return NULL;
1205 
1206         *orig = fl6->daddr;
1207 
1208         switch (opt->srcrt->type) {
1209         case IPV6_SRCRT_TYPE_0:
1210         case IPV6_SRCRT_STRICT:
1211         case IPV6_SRCRT_TYPE_2:
1212                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1213                 break;
1214         case IPV6_SRCRT_TYPE_4:
1215         {
1216                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1217 
1218                 fl6->daddr = srh->segments[srh->segments_left];
1219                 break;
1220         }
1221         default:
1222                 return NULL;
1223         }
1224 
1225         return orig;
1226 }
1227 EXPORT_SYMBOL_GPL(fl6_update_dst);
1228 

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