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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IPv6 input
4 * Linux INET6 implementation
5 *
6 * Authors:
7 * Pedro Roque <roque@di.fc.ul.pt>
8 * Ian P. Morris <I.P.Morris@soton.ac.uk>
9 *
10 * Based in linux/net/ipv4/ip_input.c
11 */
12/* Changes
13 *
14 * Mitsuru KANDA @USAGI and
15 * YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
16 */
17
18#include <linux/errno.h>
19#include <linux/types.h>
20#include <linux/socket.h>
21#include <linux/sockios.h>
22#include <linux/net.h>
23#include <linux/netdevice.h>
24#include <linux/in6.h>
25#include <linux/icmpv6.h>
26#include <linux/mroute6.h>
27#include <linux/slab.h>
28#include <linux/indirect_call_wrapper.h>
29
30#include <linux/netfilter.h>
31#include <linux/netfilter_ipv6.h>
32
33#include <net/sock.h>
34#include <net/snmp.h>
35#include <net/udp.h>
36
37#include <net/ipv6.h>
38#include <net/protocol.h>
39#include <net/transp_v6.h>
40#include <net/rawv6.h>
41#include <net/ndisc.h>
42#include <net/ip6_route.h>
43#include <net/addrconf.h>
44#include <net/xfrm.h>
45#include <net/inet_ecn.h>
46#include <net/dst_metadata.h>
47
48static void ip6_rcv_finish_core(struct net *net, struct sock *sk,
49 struct sk_buff *skb)
50{
51 if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
52 !skb_dst(skb) && !skb->sk) {
53 switch (ipv6_hdr(skb)->nexthdr) {
54 case IPPROTO_TCP:
55 if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux))
56 tcp_v6_early_demux(skb);
57 break;
58 case IPPROTO_UDP:
59 if (READ_ONCE(net->ipv4.sysctl_udp_early_demux))
60 udp_v6_early_demux(skb);
61 break;
62 }
63 }
64
65 if (!skb_valid_dst(skb))
66 ip6_route_input(skb);
67}
68
69int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
70{
71 /* if ingress device is enslaved to an L3 master device pass the
72 * skb to its handler for processing
73 */
74 skb = l3mdev_ip6_rcv(skb);
75 if (!skb)
76 return NET_RX_SUCCESS;
77 ip6_rcv_finish_core(net, sk, skb);
78
79 return dst_input(skb);
80}
81
82static void ip6_sublist_rcv_finish(struct list_head *head)
83{
84 struct sk_buff *skb, *next;
85
86 list_for_each_entry_safe(skb, next, head, list) {
87 skb_list_del_init(skb);
88 dst_input(skb);
89 }
90}
91
92static bool ip6_can_use_hint(const struct sk_buff *skb,
93 const struct sk_buff *hint)
94{
95 return hint && !skb_dst(skb) &&
96 ipv6_addr_equal(&ipv6_hdr(hint)->daddr, &ipv6_hdr(skb)->daddr);
97}
98
99static struct sk_buff *ip6_extract_route_hint(const struct net *net,
100 struct sk_buff *skb)
101{
102 if (fib6_routes_require_src(net) || fib6_has_custom_rules(net) ||
103 IP6CB(skb)->flags & IP6SKB_MULTIPATH)
104 return NULL;
105
106 return skb;
107}
108
109static void ip6_list_rcv_finish(struct net *net, struct sock *sk,
110 struct list_head *head)
111{
112 struct sk_buff *skb, *next, *hint = NULL;
113 struct dst_entry *curr_dst = NULL;
114 LIST_HEAD(sublist);
115
116 list_for_each_entry_safe(skb, next, head, list) {
117 struct dst_entry *dst;
118
119 skb_list_del_init(skb);
120 /* if ingress device is enslaved to an L3 master device pass the
121 * skb to its handler for processing
122 */
123 skb = l3mdev_ip6_rcv(skb);
124 if (!skb)
125 continue;
126
127 if (ip6_can_use_hint(skb, hint))
128 skb_dst_copy(skb, hint);
129 else
130 ip6_rcv_finish_core(net, sk, skb);
131 dst = skb_dst(skb);
132 if (curr_dst != dst) {
133 hint = ip6_extract_route_hint(net, skb);
134
135 /* dispatch old sublist */
136 if (!list_empty(&sublist))
137 ip6_sublist_rcv_finish(&sublist);
138 /* start new sublist */
139 INIT_LIST_HEAD(&sublist);
140 curr_dst = dst;
141 }
142 list_add_tail(&skb->list, &sublist);
143 }
144 /* dispatch final sublist */
145 ip6_sublist_rcv_finish(&sublist);
146}
147
148static struct sk_buff *ip6_rcv_core(struct sk_buff *skb, struct net_device *dev,
149 struct net *net)
150{
151 enum skb_drop_reason reason;
152 const struct ipv6hdr *hdr;
153 u32 pkt_len;
154 struct inet6_dev *idev;
155
156 if (skb->pkt_type == PACKET_OTHERHOST) {
157 dev_core_stats_rx_otherhost_dropped_inc(skb->dev);
158 kfree_skb_reason(skb, SKB_DROP_REASON_OTHERHOST);
159 return NULL;
160 }
161
162 rcu_read_lock();
163
164 idev = __in6_dev_get(skb->dev);
165
166 __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);
167
168 SKB_DR_SET(reason, NOT_SPECIFIED);
169 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
170 !idev || unlikely(READ_ONCE(idev->cnf.disable_ipv6))) {
171 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
172 if (idev && unlikely(READ_ONCE(idev->cnf.disable_ipv6)))
173 SKB_DR_SET(reason, IPV6DISABLED);
174 goto drop;
175 }
176
177 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
178
179 /*
180 * Store incoming device index. When the packet will
181 * be queued, we cannot refer to skb->dev anymore.
182 *
183 * BTW, when we send a packet for our own local address on a
184 * non-loopback interface (e.g. ethX), it is being delivered
185 * via the loopback interface (lo) here; skb->dev = loopback_dev.
186 * It, however, should be considered as if it is being
187 * arrived via the sending interface (ethX), because of the
188 * nature of scoping architecture. --yoshfuji
189 */
190 IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
191
192 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
193 goto err;
194
195 hdr = ipv6_hdr(skb);
196
197 if (hdr->version != 6) {
198 SKB_DR_SET(reason, UNHANDLED_PROTO);
199 goto err;
200 }
201
202 __IP6_ADD_STATS(net, idev,
203 IPSTATS_MIB_NOECTPKTS +
204 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
205 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
206 /*
207 * RFC4291 2.5.3
208 * The loopback address must not be used as the source address in IPv6
209 * packets that are sent outside of a single node. [..]
210 * A packet received on an interface with a destination address
211 * of loopback must be dropped.
212 */
213 if ((ipv6_addr_loopback(&hdr->saddr) ||
214 ipv6_addr_loopback(&hdr->daddr)) &&
215 !(dev->flags & IFF_LOOPBACK) &&
216 !netif_is_l3_master(dev))
217 goto err;
218
219 /* RFC4291 Errata ID: 3480
220 * Interface-Local scope spans only a single interface on a
221 * node and is useful only for loopback transmission of
222 * multicast. Packets with interface-local scope received
223 * from another node must be discarded.
224 */
225 if (!(skb->pkt_type == PACKET_LOOPBACK ||
226 dev->flags & IFF_LOOPBACK) &&
227 ipv6_addr_is_multicast(&hdr->daddr) &&
228 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
229 goto err;
230
231 /* If enabled, drop unicast packets that were encapsulated in link-layer
232 * multicast or broadcast to protected against the so-called "hole-196"
233 * attack in 802.11 wireless.
234 */
235 if (!ipv6_addr_is_multicast(&hdr->daddr) &&
236 (skb->pkt_type == PACKET_BROADCAST ||
237 skb->pkt_type == PACKET_MULTICAST) &&
238 READ_ONCE(idev->cnf.drop_unicast_in_l2_multicast)) {
239 SKB_DR_SET(reason, UNICAST_IN_L2_MULTICAST);
240 goto err;
241 }
242
243 /* RFC4291 2.7
244 * Nodes must not originate a packet to a multicast address whose scope
245 * field contains the reserved value 0; if such a packet is received, it
246 * must be silently dropped.
247 */
248 if (ipv6_addr_is_multicast(&hdr->daddr) &&
249 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
250 goto err;
251
252 /*
253 * RFC4291 2.7
254 * Multicast addresses must not be used as source addresses in IPv6
255 * packets or appear in any Routing header.
256 */
257 if (ipv6_addr_is_multicast(&hdr->saddr))
258 goto err;
259
260 skb->transport_header = skb->network_header + sizeof(*hdr);
261 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
262
263 pkt_len = ntohs(hdr->payload_len);
264
265 /* pkt_len may be zero if Jumbo payload option is present */
266 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
267 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
268 __IP6_INC_STATS(net,
269 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
270 SKB_DR_SET(reason, PKT_TOO_SMALL);
271 goto drop;
272 }
273 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr)))
274 goto err;
275 hdr = ipv6_hdr(skb);
276 }
277
278 if (hdr->nexthdr == NEXTHDR_HOP) {
279 if (ipv6_parse_hopopts(skb) < 0) {
280 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
281 rcu_read_unlock();
282 return NULL;
283 }
284 }
285
286 rcu_read_unlock();
287
288 /* Must drop socket now because of tproxy. */
289 if (!skb_sk_is_prefetched(skb))
290 skb_orphan(skb);
291
292 return skb;
293err:
294 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
295 SKB_DR_OR(reason, IP_INHDR);
296drop:
297 rcu_read_unlock();
298 kfree_skb_reason(skb, reason);
299 return NULL;
300}
301
302int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
303{
304 struct net *net = dev_net(skb->dev);
305
306 skb = ip6_rcv_core(skb, dev, net);
307 if (skb == NULL)
308 return NET_RX_DROP;
309 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
310 net, NULL, skb, dev, NULL,
311 ip6_rcv_finish);
312}
313
314static void ip6_sublist_rcv(struct list_head *head, struct net_device *dev,
315 struct net *net)
316{
317 NF_HOOK_LIST(NFPROTO_IPV6, NF_INET_PRE_ROUTING, net, NULL,
318 head, dev, NULL, ip6_rcv_finish);
319 ip6_list_rcv_finish(net, NULL, head);
320}
321
322/* Receive a list of IPv6 packets */
323void ipv6_list_rcv(struct list_head *head, struct packet_type *pt,
324 struct net_device *orig_dev)
325{
326 struct net_device *curr_dev = NULL;
327 struct net *curr_net = NULL;
328 struct sk_buff *skb, *next;
329 LIST_HEAD(sublist);
330
331 list_for_each_entry_safe(skb, next, head, list) {
332 struct net_device *dev = skb->dev;
333 struct net *net = dev_net(dev);
334
335 skb_list_del_init(skb);
336 skb = ip6_rcv_core(skb, dev, net);
337 if (skb == NULL)
338 continue;
339
340 if (curr_dev != dev || curr_net != net) {
341 /* dispatch old sublist */
342 if (!list_empty(&sublist))
343 ip6_sublist_rcv(&sublist, curr_dev, curr_net);
344 /* start new sublist */
345 INIT_LIST_HEAD(&sublist);
346 curr_dev = dev;
347 curr_net = net;
348 }
349 list_add_tail(&skb->list, &sublist);
350 }
351 /* dispatch final sublist */
352 if (!list_empty(&sublist))
353 ip6_sublist_rcv(&sublist, curr_dev, curr_net);
354}
355
356INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *));
357
358/*
359 * Deliver the packet to the host
360 */
361void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr,
362 bool have_final)
363{
364 const struct inet6_protocol *ipprot;
365 struct inet6_dev *idev;
366 unsigned int nhoff;
367 SKB_DR(reason);
368 bool raw;
369
370 /*
371 * Parse extension headers
372 */
373
374resubmit:
375 idev = ip6_dst_idev(skb_dst(skb));
376 nhoff = IP6CB(skb)->nhoff;
377 if (!have_final) {
378 if (!pskb_pull(skb, skb_transport_offset(skb)))
379 goto discard;
380 nexthdr = skb_network_header(skb)[nhoff];
381 }
382
383resubmit_final:
384 raw = raw6_local_deliver(skb, nexthdr);
385 ipprot = rcu_dereference(inet6_protos[nexthdr]);
386 if (ipprot) {
387 int ret;
388
389 if (have_final) {
390 if (!(ipprot->flags & INET6_PROTO_FINAL)) {
391 /* Once we've seen a final protocol don't
392 * allow encapsulation on any non-final
393 * ones. This allows foo in UDP encapsulation
394 * to work.
395 */
396 goto discard;
397 }
398 } else if (ipprot->flags & INET6_PROTO_FINAL) {
399 const struct ipv6hdr *hdr;
400 int sdif = inet6_sdif(skb);
401 struct net_device *dev;
402
403 /* Only do this once for first final protocol */
404 have_final = true;
405
406
407 skb_postpull_rcsum(skb, skb_network_header(skb),
408 skb_network_header_len(skb));
409 hdr = ipv6_hdr(skb);
410
411 /* skb->dev passed may be master dev for vrfs. */
412 if (sdif) {
413 dev = dev_get_by_index_rcu(net, sdif);
414 if (!dev)
415 goto discard;
416 } else {
417 dev = skb->dev;
418 }
419
420 if (ipv6_addr_is_multicast(&hdr->daddr) &&
421 !ipv6_chk_mcast_addr(dev, &hdr->daddr,
422 &hdr->saddr) &&
423 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb))) {
424 SKB_DR_SET(reason, IP_INADDRERRORS);
425 goto discard;
426 }
427 }
428 if (!(ipprot->flags & INET6_PROTO_NOPOLICY)) {
429 if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
430 SKB_DR_SET(reason, XFRM_POLICY);
431 goto discard;
432 }
433 nf_reset_ct(skb);
434 }
435
436 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv,
437 skb);
438 if (ret > 0) {
439 if (ipprot->flags & INET6_PROTO_FINAL) {
440 /* Not an extension header, most likely UDP
441 * encapsulation. Use return value as nexthdr
442 * protocol not nhoff (which presumably is
443 * not set by handler).
444 */
445 nexthdr = ret;
446 goto resubmit_final;
447 } else {
448 goto resubmit;
449 }
450 } else if (ret == 0) {
451 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
452 }
453 } else {
454 if (!raw) {
455 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
456 __IP6_INC_STATS(net, idev,
457 IPSTATS_MIB_INUNKNOWNPROTOS);
458 icmpv6_send(skb, ICMPV6_PARAMPROB,
459 ICMPV6_UNK_NEXTHDR, nhoff);
460 SKB_DR_SET(reason, IP_NOPROTO);
461 } else {
462 SKB_DR_SET(reason, XFRM_POLICY);
463 }
464 kfree_skb_reason(skb, reason);
465 } else {
466 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
467 consume_skb(skb);
468 }
469 }
470 return;
471
472discard:
473 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
474 kfree_skb_reason(skb, reason);
475}
476
477static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
478{
479 skb_clear_delivery_time(skb);
480 rcu_read_lock();
481 ip6_protocol_deliver_rcu(net, skb, 0, false);
482 rcu_read_unlock();
483
484 return 0;
485}
486
487
488int ip6_input(struct sk_buff *skb)
489{
490 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
491 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
492 ip6_input_finish);
493}
494EXPORT_SYMBOL_GPL(ip6_input);
495
496int ip6_mc_input(struct sk_buff *skb)
497{
498 int sdif = inet6_sdif(skb);
499 const struct ipv6hdr *hdr;
500 struct net_device *dev;
501 bool deliver;
502
503 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
504 __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST,
505 skb->len);
506
507 /* skb->dev passed may be master dev for vrfs. */
508 if (sdif) {
509 rcu_read_lock();
510 dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif);
511 if (!dev) {
512 rcu_read_unlock();
513 kfree_skb(skb);
514 return -ENODEV;
515 }
516 } else {
517 dev = skb->dev;
518 }
519
520 hdr = ipv6_hdr(skb);
521 deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL);
522 if (sdif)
523 rcu_read_unlock();
524
525#ifdef CONFIG_IPV6_MROUTE
526 /*
527 * IPv6 multicast router mode is now supported ;)
528 */
529 if (atomic_read(&dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding) &&
530 !(ipv6_addr_type(&hdr->daddr) &
531 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
532 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
533 /*
534 * Okay, we try to forward - split and duplicate
535 * packets.
536 */
537 struct sk_buff *skb2;
538 struct inet6_skb_parm *opt = IP6CB(skb);
539
540 /* Check for MLD */
541 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
542 /* Check if this is a mld message */
543 u8 nexthdr = hdr->nexthdr;
544 __be16 frag_off;
545 int offset;
546
547 /* Check if the value of Router Alert
548 * is for MLD (0x0000).
549 */
550 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
551 deliver = false;
552
553 if (!ipv6_ext_hdr(nexthdr)) {
554 /* BUG */
555 goto out;
556 }
557 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
558 &nexthdr, &frag_off);
559 if (offset < 0)
560 goto out;
561
562 if (ipv6_is_mld(skb, nexthdr, offset))
563 deliver = true;
564
565 goto out;
566 }
567 /* unknown RA - process it normally */
568 }
569
570 if (deliver)
571 skb2 = skb_clone(skb, GFP_ATOMIC);
572 else {
573 skb2 = skb;
574 skb = NULL;
575 }
576
577 if (skb2) {
578 ip6_mr_input(skb2);
579 }
580 }
581out:
582#endif
583 if (likely(deliver))
584 ip6_input(skb);
585 else {
586 /* discard */
587 kfree_skb(skb);
588 }
589
590 return 0;
591}
1/*
2 * IPv6 input
3 * Linux INET6 implementation
4 *
5 * Authors:
6 * Pedro Roque <roque@di.fc.ul.pt>
7 * Ian P. Morris <I.P.Morris@soton.ac.uk>
8 *
9 * Based in linux/net/ipv4/ip_input.c
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 */
16/* Changes
17 *
18 * Mitsuru KANDA @USAGI and
19 * YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
20 */
21
22#include <linux/errno.h>
23#include <linux/types.h>
24#include <linux/socket.h>
25#include <linux/sockios.h>
26#include <linux/net.h>
27#include <linux/netdevice.h>
28#include <linux/in6.h>
29#include <linux/icmpv6.h>
30#include <linux/mroute6.h>
31#include <linux/slab.h>
32
33#include <linux/netfilter.h>
34#include <linux/netfilter_ipv6.h>
35
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/xfrm.h>
47#include <net/inet_ecn.h>
48#include <net/dst_metadata.h>
49
50int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
51{
52 /* if ingress device is enslaved to an L3 master device pass the
53 * skb to its handler for processing
54 */
55 skb = l3mdev_ip6_rcv(skb);
56 if (!skb)
57 return NET_RX_SUCCESS;
58
59 if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
60 const struct inet6_protocol *ipprot;
61
62 ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
63 if (ipprot && ipprot->early_demux)
64 ipprot->early_demux(skb);
65 }
66 if (!skb_valid_dst(skb))
67 ip6_route_input(skb);
68
69 return dst_input(skb);
70}
71
72int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
73{
74 const struct ipv6hdr *hdr;
75 u32 pkt_len;
76 struct inet6_dev *idev;
77 struct net *net = dev_net(skb->dev);
78
79 if (skb->pkt_type == PACKET_OTHERHOST) {
80 kfree_skb(skb);
81 return NET_RX_DROP;
82 }
83
84 rcu_read_lock();
85
86 idev = __in6_dev_get(skb->dev);
87
88 __IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);
89
90 if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
91 !idev || unlikely(idev->cnf.disable_ipv6)) {
92 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
93 goto drop;
94 }
95
96 memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));
97
98 /*
99 * Store incoming device index. When the packet will
100 * be queued, we cannot refer to skb->dev anymore.
101 *
102 * BTW, when we send a packet for our own local address on a
103 * non-loopback interface (e.g. ethX), it is being delivered
104 * via the loopback interface (lo) here; skb->dev = loopback_dev.
105 * It, however, should be considered as if it is being
106 * arrived via the sending interface (ethX), because of the
107 * nature of scoping architecture. --yoshfuji
108 */
109 IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;
110
111 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
112 goto err;
113
114 hdr = ipv6_hdr(skb);
115
116 if (hdr->version != 6)
117 goto err;
118
119 __IP6_ADD_STATS(net, idev,
120 IPSTATS_MIB_NOECTPKTS +
121 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
122 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
123 /*
124 * RFC4291 2.5.3
125 * A packet received on an interface with a destination address
126 * of loopback must be dropped.
127 */
128 if (!(dev->flags & IFF_LOOPBACK) &&
129 ipv6_addr_loopback(&hdr->daddr))
130 goto err;
131
132 /* RFC4291 Errata ID: 3480
133 * Interface-Local scope spans only a single interface on a
134 * node and is useful only for loopback transmission of
135 * multicast. Packets with interface-local scope received
136 * from another node must be discarded.
137 */
138 if (!(skb->pkt_type == PACKET_LOOPBACK ||
139 dev->flags & IFF_LOOPBACK) &&
140 ipv6_addr_is_multicast(&hdr->daddr) &&
141 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
142 goto err;
143
144 /* If enabled, drop unicast packets that were encapsulated in link-layer
145 * multicast or broadcast to protected against the so-called "hole-196"
146 * attack in 802.11 wireless.
147 */
148 if (!ipv6_addr_is_multicast(&hdr->daddr) &&
149 (skb->pkt_type == PACKET_BROADCAST ||
150 skb->pkt_type == PACKET_MULTICAST) &&
151 idev->cnf.drop_unicast_in_l2_multicast)
152 goto err;
153
154 /* RFC4291 2.7
155 * Nodes must not originate a packet to a multicast address whose scope
156 * field contains the reserved value 0; if such a packet is received, it
157 * must be silently dropped.
158 */
159 if (ipv6_addr_is_multicast(&hdr->daddr) &&
160 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
161 goto err;
162
163 /*
164 * RFC4291 2.7
165 * Multicast addresses must not be used as source addresses in IPv6
166 * packets or appear in any Routing header.
167 */
168 if (ipv6_addr_is_multicast(&hdr->saddr))
169 goto err;
170
171 skb->transport_header = skb->network_header + sizeof(*hdr);
172 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
173
174 pkt_len = ntohs(hdr->payload_len);
175
176 /* pkt_len may be zero if Jumbo payload option is present */
177 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
178 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
179 __IP6_INC_STATS(net,
180 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
181 goto drop;
182 }
183 if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
184 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
185 goto drop;
186 }
187 hdr = ipv6_hdr(skb);
188 }
189
190 if (hdr->nexthdr == NEXTHDR_HOP) {
191 if (ipv6_parse_hopopts(skb) < 0) {
192 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
193 rcu_read_unlock();
194 return NET_RX_DROP;
195 }
196 }
197
198 rcu_read_unlock();
199
200 /* Must drop socket now because of tproxy. */
201 skb_orphan(skb);
202
203 return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
204 net, NULL, skb, dev, NULL,
205 ip6_rcv_finish);
206err:
207 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
208drop:
209 rcu_read_unlock();
210 kfree_skb(skb);
211 return NET_RX_DROP;
212}
213
214/*
215 * Deliver the packet to the host
216 */
217
218
219static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
220{
221 const struct inet6_protocol *ipprot;
222 struct inet6_dev *idev;
223 unsigned int nhoff;
224 int nexthdr;
225 bool raw;
226 bool have_final = false;
227
228 /*
229 * Parse extension headers
230 */
231
232 rcu_read_lock();
233resubmit:
234 idev = ip6_dst_idev(skb_dst(skb));
235 if (!pskb_pull(skb, skb_transport_offset(skb)))
236 goto discard;
237 nhoff = IP6CB(skb)->nhoff;
238 nexthdr = skb_network_header(skb)[nhoff];
239
240resubmit_final:
241 raw = raw6_local_deliver(skb, nexthdr);
242 ipprot = rcu_dereference(inet6_protos[nexthdr]);
243 if (ipprot) {
244 int ret;
245
246 if (have_final) {
247 if (!(ipprot->flags & INET6_PROTO_FINAL)) {
248 /* Once we've seen a final protocol don't
249 * allow encapsulation on any non-final
250 * ones. This allows foo in UDP encapsulation
251 * to work.
252 */
253 goto discard;
254 }
255 } else if (ipprot->flags & INET6_PROTO_FINAL) {
256 const struct ipv6hdr *hdr;
257
258 /* Only do this once for first final protocol */
259 have_final = true;
260
261 /* Free reference early: we don't need it any more,
262 and it may hold ip_conntrack module loaded
263 indefinitely. */
264 nf_reset(skb);
265
266 skb_postpull_rcsum(skb, skb_network_header(skb),
267 skb_network_header_len(skb));
268 hdr = ipv6_hdr(skb);
269 if (ipv6_addr_is_multicast(&hdr->daddr) &&
270 !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
271 &hdr->saddr) &&
272 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
273 goto discard;
274 }
275 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
276 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
277 goto discard;
278
279 ret = ipprot->handler(skb);
280 if (ret > 0) {
281 if (ipprot->flags & INET6_PROTO_FINAL) {
282 /* Not an extension header, most likely UDP
283 * encapsulation. Use return value as nexthdr
284 * protocol not nhoff (which presumably is
285 * not set by handler).
286 */
287 nexthdr = ret;
288 goto resubmit_final;
289 } else {
290 goto resubmit;
291 }
292 } else if (ret == 0) {
293 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
294 }
295 } else {
296 if (!raw) {
297 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
298 __IP6_INC_STATS(net, idev,
299 IPSTATS_MIB_INUNKNOWNPROTOS);
300 icmpv6_send(skb, ICMPV6_PARAMPROB,
301 ICMPV6_UNK_NEXTHDR, nhoff);
302 }
303 kfree_skb(skb);
304 } else {
305 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
306 consume_skb(skb);
307 }
308 }
309 rcu_read_unlock();
310 return 0;
311
312discard:
313 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
314 rcu_read_unlock();
315 kfree_skb(skb);
316 return 0;
317}
318
319
320int ip6_input(struct sk_buff *skb)
321{
322 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
323 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
324 ip6_input_finish);
325}
326EXPORT_SYMBOL_GPL(ip6_input);
327
328int ip6_mc_input(struct sk_buff *skb)
329{
330 const struct ipv6hdr *hdr;
331 bool deliver;
332
333 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
334 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
335 skb->len);
336
337 hdr = ipv6_hdr(skb);
338 deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);
339
340#ifdef CONFIG_IPV6_MROUTE
341 /*
342 * IPv6 multicast router mode is now supported ;)
343 */
344 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
345 !(ipv6_addr_type(&hdr->daddr) &
346 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
347 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
348 /*
349 * Okay, we try to forward - split and duplicate
350 * packets.
351 */
352 struct sk_buff *skb2;
353 struct inet6_skb_parm *opt = IP6CB(skb);
354
355 /* Check for MLD */
356 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
357 /* Check if this is a mld message */
358 u8 nexthdr = hdr->nexthdr;
359 __be16 frag_off;
360 int offset;
361
362 /* Check if the value of Router Alert
363 * is for MLD (0x0000).
364 */
365 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
366 deliver = false;
367
368 if (!ipv6_ext_hdr(nexthdr)) {
369 /* BUG */
370 goto out;
371 }
372 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
373 &nexthdr, &frag_off);
374 if (offset < 0)
375 goto out;
376
377 if (ipv6_is_mld(skb, nexthdr, offset))
378 deliver = true;
379
380 goto out;
381 }
382 /* unknown RA - process it normally */
383 }
384
385 if (deliver)
386 skb2 = skb_clone(skb, GFP_ATOMIC);
387 else {
388 skb2 = skb;
389 skb = NULL;
390 }
391
392 if (skb2) {
393 ip6_mr_input(skb2);
394 }
395 }
396out:
397#endif
398 if (likely(deliver))
399 ip6_input(skb);
400 else {
401 /* discard */
402 kfree_skb(skb);
403 }
404
405 return 0;
406}