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