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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_dev *idev = __in6_dev_get(skb->dev);
284         struct inet6_skb_parm *opt = IP6CB(skb);
285 #if IS_ENABLED(CONFIG_IPV6_MIP6)
286         __u16 dstbuf;
287 #endif
288         struct dst_entry *dst = skb_dst(skb);
289         struct net *net = dev_net(skb->dev);
290         int extlen;
291 
292         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
293             !pskb_may_pull(skb, (skb_transport_offset(skb) +
294                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
295                 __IP6_INC_STATS(dev_net(dst->dev), idev,
296                                 IPSTATS_MIB_INHDRERRORS);
297 fail_and_free:
298                 kfree_skb(skb);
299                 return -1;
300         }
301 
302         extlen = (skb_transport_header(skb)[1] + 1) << 3;
303         if (extlen > net->ipv6.sysctl.max_dst_opts_len)
304                 goto fail_and_free;
305 
306         opt->lastopt = opt->dst1 = skb_network_header_len(skb);
307 #if IS_ENABLED(CONFIG_IPV6_MIP6)
308         dstbuf = opt->dst1;
309 #endif
310 
311         if (ip6_parse_tlv(tlvprocdestopt_lst, skb,
312                           init_net.ipv6.sysctl.max_dst_opts_cnt)) {
313                 skb->transport_header += extlen;
314                 opt = IP6CB(skb);
315 #if IS_ENABLED(CONFIG_IPV6_MIP6)
316                 opt->nhoff = dstbuf;
317 #else
318                 opt->nhoff = opt->dst1;
319 #endif
320                 return 1;
321         }
322 
323         __IP6_INC_STATS(net, idev, 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, idev, IPSTATS_MIB_INHDRERRORS);
420                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
421                                   ((&hdr->segments_left) -
422                                    skb_network_header(skb)));
423                 return -1;
424         }
425 
426         if (skb_cloned(skb)) {
427                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
428                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
429                                         IPSTATS_MIB_OUTDISCARDS);
430                         kfree_skb(skb);
431                         return -1;
432                 }
433         }
434 
435         hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb);
436 
437         hdr->segments_left--;
438         addr = hdr->segments + hdr->segments_left;
439 
440         skb_push(skb, sizeof(struct ipv6hdr));
441 
442         if (skb->ip_summed == CHECKSUM_COMPLETE)
443                 seg6_update_csum(skb);
444 
445         ipv6_hdr(skb)->daddr = *addr;
446 
447         skb_dst_drop(skb);
448 
449         ip6_route_input(skb);
450 
451         if (skb_dst(skb)->error) {
452                 dst_input(skb);
453                 return -1;
454         }
455 
456         if (skb_dst(skb)->dev->flags & IFF_LOOPBACK) {
457                 if (ipv6_hdr(skb)->hop_limit <= 1) {
458                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
459                         icmpv6_send(skb, ICMPV6_TIME_EXCEED,
460                                     ICMPV6_EXC_HOPLIMIT, 0);
461                         kfree_skb(skb);
462                         return -1;
463                 }
464                 ipv6_hdr(skb)->hop_limit--;
465 
466                 skb_pull(skb, sizeof(struct ipv6hdr));
467                 goto looped_back;
468         }
469 
470         dst_input(skb);
471 
472         return -1;
473 }
474 
475 /********************************
476   Routing header.
477  ********************************/
478 
479 /* called with rcu_read_lock() */
480 static int ipv6_rthdr_rcv(struct sk_buff *skb)
481 {
482         struct inet6_dev *idev = __in6_dev_get(skb->dev);
483         struct inet6_skb_parm *opt = IP6CB(skb);
484         struct in6_addr *addr = NULL;
485         struct in6_addr daddr;
486         int n, i;
487         struct ipv6_rt_hdr *hdr;
488         struct rt0_hdr *rthdr;
489         struct net *net = dev_net(skb->dev);
490         int accept_source_route = net->ipv6.devconf_all->accept_source_route;
491 
492         idev = __in6_dev_get(skb->dev);
493         if (idev && accept_source_route > idev->cnf.accept_source_route)
494                 accept_source_route = idev->cnf.accept_source_route;
495 
496         if (!pskb_may_pull(skb, skb_transport_offset(skb) + 8) ||
497             !pskb_may_pull(skb, (skb_transport_offset(skb) +
498                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
499                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
500                 kfree_skb(skb);
501                 return -1;
502         }
503 
504         hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
505 
506         if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr) ||
507             skb->pkt_type != PACKET_HOST) {
508                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
509                 kfree_skb(skb);
510                 return -1;
511         }
512 
513         /* segment routing */
514         if (hdr->type == IPV6_SRCRT_TYPE_4)
515                 return ipv6_srh_rcv(skb);
516 
517 looped_back:
518         if (hdr->segments_left == 0) {
519                 switch (hdr->type) {
520 #if IS_ENABLED(CONFIG_IPV6_MIP6)
521                 case IPV6_SRCRT_TYPE_2:
522                         /* Silently discard type 2 header unless it was
523                          * processed by own
524                          */
525                         if (!addr) {
526                                 __IP6_INC_STATS(net, idev,
527                                                 IPSTATS_MIB_INADDRERRORS);
528                                 kfree_skb(skb);
529                                 return -1;
530                         }
531                         break;
532 #endif
533                 default:
534                         break;
535                 }
536 
537                 opt->lastopt = opt->srcrt = skb_network_header_len(skb);
538                 skb->transport_header += (hdr->hdrlen + 1) << 3;
539                 opt->dst0 = opt->dst1;
540                 opt->dst1 = 0;
541                 opt->nhoff = (&hdr->nexthdr) - skb_network_header(skb);
542                 return 1;
543         }
544 
545         switch (hdr->type) {
546 #if IS_ENABLED(CONFIG_IPV6_MIP6)
547         case IPV6_SRCRT_TYPE_2:
548                 if (accept_source_route < 0)
549                         goto unknown_rh;
550                 /* Silently discard invalid RTH type 2 */
551                 if (hdr->hdrlen != 2 || hdr->segments_left != 1) {
552                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
553                         kfree_skb(skb);
554                         return -1;
555                 }
556                 break;
557 #endif
558         default:
559                 goto unknown_rh;
560         }
561 
562         /*
563          *      This is the routing header forwarding algorithm from
564          *      RFC 2460, page 16.
565          */
566 
567         n = hdr->hdrlen >> 1;
568 
569         if (hdr->segments_left > n) {
570                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
571                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
572                                   ((&hdr->segments_left) -
573                                    skb_network_header(skb)));
574                 return -1;
575         }
576 
577         /* We are about to mangle packet header. Be careful!
578            Do not damage packets queued somewhere.
579          */
580         if (skb_cloned(skb)) {
581                 /* the copy is a forwarded packet */
582                 if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) {
583                         __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
584                                         IPSTATS_MIB_OUTDISCARDS);
585                         kfree_skb(skb);
586                         return -1;
587                 }
588                 hdr = (struct ipv6_rt_hdr *)skb_transport_header(skb);
589         }
590 
591         if (skb->ip_summed == CHECKSUM_COMPLETE)
592                 skb->ip_summed = CHECKSUM_NONE;
593 
594         i = n - --hdr->segments_left;
595 
596         rthdr = (struct rt0_hdr *) hdr;
597         addr = rthdr->addr;
598         addr += i - 1;
599 
600         switch (hdr->type) {
601 #if IS_ENABLED(CONFIG_IPV6_MIP6)
602         case IPV6_SRCRT_TYPE_2:
603                 if (xfrm6_input_addr(skb, (xfrm_address_t *)addr,
604                                      (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
605                                      IPPROTO_ROUTING) < 0) {
606                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
607                         kfree_skb(skb);
608                         return -1;
609                 }
610                 if (!ipv6_chk_home_addr(dev_net(skb_dst(skb)->dev), addr)) {
611                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
612                         kfree_skb(skb);
613                         return -1;
614                 }
615                 break;
616 #endif
617         default:
618                 break;
619         }
620 
621         if (ipv6_addr_is_multicast(addr)) {
622                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
623                 kfree_skb(skb);
624                 return -1;
625         }
626 
627         daddr = *addr;
628         *addr = ipv6_hdr(skb)->daddr;
629         ipv6_hdr(skb)->daddr = daddr;
630 
631         skb_dst_drop(skb);
632         ip6_route_input(skb);
633         if (skb_dst(skb)->error) {
634                 skb_push(skb, skb->data - skb_network_header(skb));
635                 dst_input(skb);
636                 return -1;
637         }
638 
639         if (skb_dst(skb)->dev->flags&IFF_LOOPBACK) {
640                 if (ipv6_hdr(skb)->hop_limit <= 1) {
641                         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
642                         icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT,
643                                     0);
644                         kfree_skb(skb);
645                         return -1;
646                 }
647                 ipv6_hdr(skb)->hop_limit--;
648                 goto looped_back;
649         }
650 
651         skb_push(skb, skb->data - skb_network_header(skb));
652         dst_input(skb);
653         return -1;
654 
655 unknown_rh:
656         __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
657         icmpv6_param_prob(skb, ICMPV6_HDR_FIELD,
658                           (&hdr->type) - skb_network_header(skb));
659         return -1;
660 }
661 
662 static const struct inet6_protocol rthdr_protocol = {
663         .handler        =       ipv6_rthdr_rcv,
664         .flags          =       INET6_PROTO_NOPOLICY,
665 };
666 
667 static const struct inet6_protocol destopt_protocol = {
668         .handler        =       ipv6_destopt_rcv,
669         .flags          =       INET6_PROTO_NOPOLICY,
670 };
671 
672 static const struct inet6_protocol nodata_protocol = {
673         .handler        =       dst_discard,
674         .flags          =       INET6_PROTO_NOPOLICY,
675 };
676 
677 int __init ipv6_exthdrs_init(void)
678 {
679         int ret;
680 
681         ret = inet6_add_protocol(&rthdr_protocol, IPPROTO_ROUTING);
682         if (ret)
683                 goto out;
684 
685         ret = inet6_add_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
686         if (ret)
687                 goto out_rthdr;
688 
689         ret = inet6_add_protocol(&nodata_protocol, IPPROTO_NONE);
690         if (ret)
691                 goto out_destopt;
692 
693 out:
694         return ret;
695 out_destopt:
696         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
697 out_rthdr:
698         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
699         goto out;
700 };
701 
702 void ipv6_exthdrs_exit(void)
703 {
704         inet6_del_protocol(&nodata_protocol, IPPROTO_NONE);
705         inet6_del_protocol(&destopt_protocol, IPPROTO_DSTOPTS);
706         inet6_del_protocol(&rthdr_protocol, IPPROTO_ROUTING);
707 }
708 
709 /**********************************
710   Hop-by-hop options.
711  **********************************/
712 
713 /*
714  * Note: we cannot rely on skb_dst(skb) before we assign it in ip6_route_input().
715  */
716 static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
717 {
718         return skb_dst(skb) ? ip6_dst_idev(skb_dst(skb)) : __in6_dev_get(skb->dev);
719 }
720 
721 static inline struct net *ipv6_skb_net(struct sk_buff *skb)
722 {
723         return skb_dst(skb) ? dev_net(skb_dst(skb)->dev) : dev_net(skb->dev);
724 }
725 
726 /* Router Alert as of RFC 2711 */
727 
728 static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
729 {
730         const unsigned char *nh = skb_network_header(skb);
731 
732         if (nh[optoff + 1] == 2) {
733                 IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
734                 memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
735                 return true;
736         }
737         net_dbg_ratelimited("ipv6_hop_ra: wrong RA length %d\n",
738                             nh[optoff + 1]);
739         kfree_skb(skb);
740         return false;
741 }
742 
743 /* Jumbo payload */
744 
745 static bool ipv6_hop_jumbo(struct sk_buff *skb, int optoff)
746 {
747         const unsigned char *nh = skb_network_header(skb);
748         struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
749         struct net *net = ipv6_skb_net(skb);
750         u32 pkt_len;
751 
752         if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
753                 net_dbg_ratelimited("ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
754                                     nh[optoff+1]);
755                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
756                 goto drop;
757         }
758 
759         pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
760         if (pkt_len <= IPV6_MAXPLEN) {
761                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
762                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
763                 return false;
764         }
765         if (ipv6_hdr(skb)->payload_len) {
766                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
767                 icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
768                 return false;
769         }
770 
771         if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
772                 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INTRUNCATEDPKTS);
773                 goto drop;
774         }
775 
776         if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
777                 goto drop;
778 
779         IP6CB(skb)->flags |= IP6SKB_JUMBOGRAM;
780         return true;
781 
782 drop:
783         kfree_skb(skb);
784         return false;
785 }
786 
787 /* CALIPSO RFC 5570 */
788 
789 static bool ipv6_hop_calipso(struct sk_buff *skb, int optoff)
790 {
791         const unsigned char *nh = skb_network_header(skb);
792 
793         if (nh[optoff + 1] < 8)
794                 goto drop;
795 
796         if (nh[optoff + 6] * 4 + 8 > nh[optoff + 1])
797                 goto drop;
798 
799         if (!calipso_validate(skb, nh + optoff))
800                 goto drop;
801 
802         return true;
803 
804 drop:
805         kfree_skb(skb);
806         return false;
807 }
808 
809 static const struct tlvtype_proc tlvprochopopt_lst[] = {
810         {
811                 .type   = IPV6_TLV_ROUTERALERT,
812                 .func   = ipv6_hop_ra,
813         },
814         {
815                 .type   = IPV6_TLV_JUMBO,
816                 .func   = ipv6_hop_jumbo,
817         },
818         {
819                 .type   = IPV6_TLV_CALIPSO,
820                 .func   = ipv6_hop_calipso,
821         },
822         { -1, }
823 };
824 
825 int ipv6_parse_hopopts(struct sk_buff *skb)
826 {
827         struct inet6_skb_parm *opt = IP6CB(skb);
828         struct net *net = dev_net(skb->dev);
829         int extlen;
830 
831         /*
832          * skb_network_header(skb) is equal to skb->data, and
833          * skb_network_header_len(skb) is always equal to
834          * sizeof(struct ipv6hdr) by definition of
835          * hop-by-hop options.
836          */
837         if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + 8) ||
838             !pskb_may_pull(skb, (sizeof(struct ipv6hdr) +
839                                  ((skb_transport_header(skb)[1] + 1) << 3)))) {
840 fail_and_free:
841                 kfree_skb(skb);
842                 return -1;
843         }
844 
845         extlen = (skb_transport_header(skb)[1] + 1) << 3;
846         if (extlen > net->ipv6.sysctl.max_hbh_opts_len)
847                 goto fail_and_free;
848 
849         opt->flags |= IP6SKB_HOPBYHOP;
850         if (ip6_parse_tlv(tlvprochopopt_lst, skb,
851                           init_net.ipv6.sysctl.max_hbh_opts_cnt)) {
852                 skb->transport_header += extlen;
853                 opt = IP6CB(skb);
854                 opt->nhoff = sizeof(struct ipv6hdr);
855                 return 1;
856         }
857         return -1;
858 }
859 
860 /*
861  *      Creating outbound headers.
862  *
863  *      "build" functions work when skb is filled from head to tail (datagram)
864  *      "push"  functions work when headers are added from tail to head (tcp)
865  *
866  *      In both cases we assume, that caller reserved enough room
867  *      for headers.
868  */
869 
870 static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
871                              struct ipv6_rt_hdr *opt,
872                              struct in6_addr **addr_p, struct in6_addr *saddr)
873 {
874         struct rt0_hdr *phdr, *ihdr;
875         int hops;
876 
877         ihdr = (struct rt0_hdr *) opt;
878 
879         phdr = skb_push(skb, (ihdr->rt_hdr.hdrlen + 1) << 3);
880         memcpy(phdr, ihdr, sizeof(struct rt0_hdr));
881 
882         hops = ihdr->rt_hdr.hdrlen >> 1;
883 
884         if (hops > 1)
885                 memcpy(phdr->addr, ihdr->addr + 1,
886                        (hops - 1) * sizeof(struct in6_addr));
887 
888         phdr->addr[hops - 1] = **addr_p;
889         *addr_p = ihdr->addr;
890 
891         phdr->rt_hdr.nexthdr = *proto;
892         *proto = NEXTHDR_ROUTING;
893 }
894 
895 static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
896                              struct ipv6_rt_hdr *opt,
897                              struct in6_addr **addr_p, struct in6_addr *saddr)
898 {
899         struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
900         int plen, hops;
901 
902         sr_ihdr = (struct ipv6_sr_hdr *)opt;
903         plen = (sr_ihdr->hdrlen + 1) << 3;
904 
905         sr_phdr = skb_push(skb, plen);
906         memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
907 
908         hops = sr_ihdr->first_segment + 1;
909         memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
910                (hops - 1) * sizeof(struct in6_addr));
911 
912         sr_phdr->segments[0] = **addr_p;
913         *addr_p = &sr_ihdr->segments[sr_ihdr->segments_left];
914 
915         if (sr_ihdr->hdrlen > hops * 2) {
916                 int tlvs_offset, tlvs_length;
917 
918                 tlvs_offset = (1 + hops * 2) << 3;
919                 tlvs_length = (sr_ihdr->hdrlen - hops * 2) << 3;
920                 memcpy((char *)sr_phdr + tlvs_offset,
921                        (char *)sr_ihdr + tlvs_offset, tlvs_length);
922         }
923 
924 #ifdef CONFIG_IPV6_SEG6_HMAC
925         if (sr_has_hmac(sr_phdr)) {
926                 struct net *net = NULL;
927 
928                 if (skb->dev)
929                         net = dev_net(skb->dev);
930                 else if (skb->sk)
931                         net = sock_net(skb->sk);
932 
933                 WARN_ON(!net);
934 
935                 if (net)
936                         seg6_push_hmac(net, saddr, sr_phdr);
937         }
938 #endif
939 
940         sr_phdr->nexthdr = *proto;
941         *proto = NEXTHDR_ROUTING;
942 }
943 
944 static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
945                             struct ipv6_rt_hdr *opt,
946                             struct in6_addr **addr_p, struct in6_addr *saddr)
947 {
948         switch (opt->type) {
949         case IPV6_SRCRT_TYPE_0:
950         case IPV6_SRCRT_STRICT:
951         case IPV6_SRCRT_TYPE_2:
952                 ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
953                 break;
954         case IPV6_SRCRT_TYPE_4:
955                 ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
956                 break;
957         default:
958                 break;
959         }
960 }
961 
962 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
963 {
964         struct ipv6_opt_hdr *h = skb_push(skb, ipv6_optlen(opt));
965 
966         memcpy(h, opt, ipv6_optlen(opt));
967         h->nexthdr = *proto;
968         *proto = type;
969 }
970 
971 void ipv6_push_nfrag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt,
972                           u8 *proto,
973                           struct in6_addr **daddr, struct in6_addr *saddr)
974 {
975         if (opt->srcrt) {
976                 ipv6_push_rthdr(skb, proto, opt->srcrt, daddr, saddr);
977                 /*
978                  * IPV6_RTHDRDSTOPTS is ignored
979                  * unless IPV6_RTHDR is set (RFC3542).
980                  */
981                 if (opt->dst0opt)
982                         ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst0opt);
983         }
984         if (opt->hopopt)
985                 ipv6_push_exthdr(skb, proto, NEXTHDR_HOP, opt->hopopt);
986 }
987 
988 void ipv6_push_frag_opts(struct sk_buff *skb, struct ipv6_txoptions *opt, u8 *proto)
989 {
990         if (opt->dst1opt)
991                 ipv6_push_exthdr(skb, proto, NEXTHDR_DEST, opt->dst1opt);
992 }
993 EXPORT_SYMBOL(ipv6_push_frag_opts);
994 
995 struct ipv6_txoptions *
996 ipv6_dup_options(struct sock *sk, struct ipv6_txoptions *opt)
997 {
998         struct ipv6_txoptions *opt2;
999 
1000         opt2 = sock_kmalloc(sk, opt->tot_len, GFP_ATOMIC);
1001         if (opt2) {
1002                 long dif = (char *)opt2 - (char *)opt;
1003                 memcpy(opt2, opt, opt->tot_len);
1004                 if (opt2->hopopt)
1005                         *((char **)&opt2->hopopt) += dif;
1006                 if (opt2->dst0opt)
1007                         *((char **)&opt2->dst0opt) += dif;
1008                 if (opt2->dst1opt)
1009                         *((char **)&opt2->dst1opt) += dif;
1010                 if (opt2->srcrt)
1011                         *((char **)&opt2->srcrt) += dif;
1012                 refcount_set(&opt2->refcnt, 1);
1013         }
1014         return opt2;
1015 }
1016 EXPORT_SYMBOL_GPL(ipv6_dup_options);
1017 
1018 static void ipv6_renew_option(int renewtype,
1019                               struct ipv6_opt_hdr **dest,
1020                               struct ipv6_opt_hdr *old,
1021                               struct ipv6_opt_hdr *new,
1022                               int newtype, char **p)
1023 {
1024         struct ipv6_opt_hdr *src;
1025 
1026         src = (renewtype == newtype ? new : old);
1027         if (!src)
1028                 return;
1029 
1030         memcpy(*p, src, ipv6_optlen(src));
1031         *dest = (struct ipv6_opt_hdr *)*p;
1032         *p += CMSG_ALIGN(ipv6_optlen(*dest));
1033 }
1034 
1035 /**
1036  * ipv6_renew_options - replace a specific ext hdr with a new one.
1037  *
1038  * @sk: sock from which to allocate memory
1039  * @opt: original options
1040  * @newtype: option type to replace in @opt
1041  * @newopt: new option of type @newtype to replace (user-mem)
1042  * @newoptlen: length of @newopt
1043  *
1044  * Returns a new set of options which is a copy of @opt with the
1045  * option type @newtype replaced with @newopt.
1046  *
1047  * @opt may be NULL, in which case a new set of options is returned
1048  * containing just @newopt.
1049  *
1050  * @newopt may be NULL, in which case the specified option type is
1051  * not copied into the new set of options.
1052  *
1053  * The new set of options is allocated from the socket option memory
1054  * buffer of @sk.
1055  */
1056 struct ipv6_txoptions *
1057 ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
1058                    int newtype, struct ipv6_opt_hdr *newopt)
1059 {
1060         int tot_len = 0;
1061         char *p;
1062         struct ipv6_txoptions *opt2;
1063 
1064         if (opt) {
1065                 if (newtype != IPV6_HOPOPTS && opt->hopopt)
1066                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
1067                 if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
1068                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
1069                 if (newtype != IPV6_RTHDR && opt->srcrt)
1070                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
1071                 if (newtype != IPV6_DSTOPTS && opt->dst1opt)
1072                         tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
1073         }
1074 
1075         if (newopt)
1076                 tot_len += CMSG_ALIGN(ipv6_optlen(newopt));
1077 
1078         if (!tot_len)
1079                 return NULL;
1080 
1081         tot_len += sizeof(*opt2);
1082         opt2 = sock_kmalloc(sk, tot_len, GFP_ATOMIC);
1083         if (!opt2)
1084                 return ERR_PTR(-ENOBUFS);
1085 
1086         memset(opt2, 0, tot_len);
1087         refcount_set(&opt2->refcnt, 1);
1088         opt2->tot_len = tot_len;
1089         p = (char *)(opt2 + 1);
1090 
1091         ipv6_renew_option(IPV6_HOPOPTS, &opt2->hopopt,
1092                           (opt ? opt->hopopt : NULL),
1093                           newopt, newtype, &p);
1094         ipv6_renew_option(IPV6_RTHDRDSTOPTS, &opt2->dst0opt,
1095                           (opt ? opt->dst0opt : NULL),
1096                           newopt, newtype, &p);
1097         ipv6_renew_option(IPV6_RTHDR,
1098                           (struct ipv6_opt_hdr **)&opt2->srcrt,
1099                           (opt ? (struct ipv6_opt_hdr *)opt->srcrt : NULL),
1100                           newopt, newtype, &p);
1101         ipv6_renew_option(IPV6_DSTOPTS, &opt2->dst1opt,
1102                           (opt ? opt->dst1opt : NULL),
1103                           newopt, newtype, &p);
1104 
1105         opt2->opt_nflen = (opt2->hopopt ? ipv6_optlen(opt2->hopopt) : 0) +
1106                           (opt2->dst0opt ? ipv6_optlen(opt2->dst0opt) : 0) +
1107                           (opt2->srcrt ? ipv6_optlen(opt2->srcrt) : 0);
1108         opt2->opt_flen = (opt2->dst1opt ? ipv6_optlen(opt2->dst1opt) : 0);
1109 
1110         return opt2;
1111 }
1112 
1113 struct ipv6_txoptions *ipv6_fixup_options(struct ipv6_txoptions *opt_space,
1114                                           struct ipv6_txoptions *opt)
1115 {
1116         /*
1117          * ignore the dest before srcrt unless srcrt is being included.
1118          * --yoshfuji
1119          */
1120         if (opt && opt->dst0opt && !opt->srcrt) {
1121                 if (opt_space != opt) {
1122                         memcpy(opt_space, opt, sizeof(*opt_space));
1123                         opt = opt_space;
1124                 }
1125                 opt->opt_nflen -= ipv6_optlen(opt->dst0opt);
1126                 opt->dst0opt = NULL;
1127         }
1128 
1129         return opt;
1130 }
1131 EXPORT_SYMBOL_GPL(ipv6_fixup_options);
1132 
1133 /**
1134  * fl6_update_dst - update flowi destination address with info given
1135  *                  by srcrt option, if any.
1136  *
1137  * @fl6: flowi6 for which daddr is to be updated
1138  * @opt: struct ipv6_txoptions in which to look for srcrt opt
1139  * @orig: copy of original daddr address if modified
1140  *
1141  * Returns NULL if no txoptions or no srcrt, otherwise returns orig
1142  * and initial value of fl6->daddr set in orig
1143  */
1144 struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
1145                                 const struct ipv6_txoptions *opt,
1146                                 struct in6_addr *orig)
1147 {
1148         if (!opt || !opt->srcrt)
1149                 return NULL;
1150 
1151         *orig = fl6->daddr;
1152 
1153         switch (opt->srcrt->type) {
1154         case IPV6_SRCRT_TYPE_0:
1155         case IPV6_SRCRT_STRICT:
1156         case IPV6_SRCRT_TYPE_2:
1157                 fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
1158                 break;
1159         case IPV6_SRCRT_TYPE_4:
1160         {
1161                 struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
1162 
1163                 fl6->daddr = srh->segments[srh->segments_left];
1164                 break;
1165         }
1166         default:
1167                 return NULL;
1168         }
1169 
1170         return orig;
1171 }
1172 EXPORT_SYMBOL_GPL(fl6_update_dst);
1173 

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