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
36 #include <net/ipv6.h>
37 #include <net/protocol.h>
38 #include <net/transp_v6.h>
39 #include <net/rawv6.h>
40 #include <net/ndisc.h>
41 #include <net/ip6_route.h>
42 #include <net/addrconf.h>
43 #include <net/xfrm.h>
44 #include <net/inet_ecn.h>
45 #include <net/dst_metadata.h>
46
47 INDIRECT_CALLABLE_DECLARE(void udp_v6_early_demux(struct sk_buff *));
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 udpv6_rcv(struct sk_buff *));
346 INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *));
347
348 /*
349 * Deliver the packet to the host
350 */
ip6_protocol_deliver_rcu(struct net * net,struct sk_buff * skb,int nexthdr,bool have_final)351 void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr,
352 bool have_final)
353 {
354 const struct inet6_protocol *ipprot;
355 struct inet6_dev *idev;
356 unsigned int nhoff;
357 bool raw;
358
359 /*
360 * Parse extension headers
361 */
362
363 resubmit:
364 idev = ip6_dst_idev(skb_dst(skb));
365 nhoff = IP6CB(skb)->nhoff;
366 if (!have_final) {
367 if (!pskb_pull(skb, skb_transport_offset(skb)))
368 goto discard;
369 nexthdr = skb_network_header(skb)[nhoff];
370 }
371
372 resubmit_final:
373 raw = raw6_local_deliver(skb, nexthdr);
374 ipprot = rcu_dereference(inet6_protos[nexthdr]);
375 if (ipprot) {
376 int ret;
377
378 if (have_final) {
379 if (!(ipprot->flags & INET6_PROTO_FINAL)) {
380 /* Once we've seen a final protocol don't
381 * allow encapsulation on any non-final
382 * ones. This allows foo in UDP encapsulation
383 * to work.
384 */
385 goto discard;
386 }
387 } else if (ipprot->flags & INET6_PROTO_FINAL) {
388 const struct ipv6hdr *hdr;
389 int sdif = inet6_sdif(skb);
390 struct net_device *dev;
391
392 /* Only do this once for first final protocol */
393 have_final = true;
394
395 /* Free reference early: we don't need it any more,
396 and it may hold ip_conntrack module loaded
397 indefinitely. */
398 nf_reset_ct(skb);
399
400 skb_postpull_rcsum(skb, skb_network_header(skb),
401 skb_network_header_len(skb));
402 hdr = ipv6_hdr(skb);
403
404 /* skb->dev passed may be master dev for vrfs. */
405 if (sdif) {
406 dev = dev_get_by_index_rcu(net, sdif);
407 if (!dev)
408 goto discard;
409 } else {
410 dev = skb->dev;
411 }
412
413 if (ipv6_addr_is_multicast(&hdr->daddr) &&
414 !ipv6_chk_mcast_addr(dev, &hdr->daddr,
415 &hdr->saddr) &&
416 !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
417 goto discard;
418 }
419 if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
420 !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
421 goto discard;
422
423 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv,
424 skb);
425 if (ret > 0) {
426 if (ipprot->flags & INET6_PROTO_FINAL) {
427 /* Not an extension header, most likely UDP
428 * encapsulation. Use return value as nexthdr
429 * protocol not nhoff (which presumably is
430 * not set by handler).
431 */
432 nexthdr = ret;
433 goto resubmit_final;
434 } else {
435 goto resubmit;
436 }
437 } else if (ret == 0) {
438 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
439 }
440 } else {
441 if (!raw) {
442 if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
443 __IP6_INC_STATS(net, idev,
444 IPSTATS_MIB_INUNKNOWNPROTOS);
445 icmpv6_send(skb, ICMPV6_PARAMPROB,
446 ICMPV6_UNK_NEXTHDR, nhoff);
447 }
448 kfree_skb(skb);
449 } else {
450 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
451 consume_skb(skb);
452 }
453 }
454 return;
455
456 discard:
457 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
458 kfree_skb(skb);
459 }
460
ip6_input_finish(struct net * net,struct sock * sk,struct sk_buff * skb)461 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
462 {
463 rcu_read_lock();
464 ip6_protocol_deliver_rcu(net, skb, 0, false);
465 rcu_read_unlock();
466
467 return 0;
468 }
469
470
ip6_input(struct sk_buff * skb)471 int ip6_input(struct sk_buff *skb)
472 {
473 return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
474 dev_net(skb->dev), NULL, skb, skb->dev, NULL,
475 ip6_input_finish);
476 }
477 EXPORT_SYMBOL_GPL(ip6_input);
478
ip6_mc_input(struct sk_buff * skb)479 int ip6_mc_input(struct sk_buff *skb)
480 {
481 int sdif = inet6_sdif(skb);
482 const struct ipv6hdr *hdr;
483 struct net_device *dev;
484 bool deliver;
485
486 __IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
487 __in6_dev_get_safely(skb->dev), IPSTATS_MIB_INMCAST,
488 skb->len);
489
490 /* skb->dev passed may be master dev for vrfs. */
491 if (sdif) {
492 rcu_read_lock();
493 dev = dev_get_by_index_rcu(dev_net(skb->dev), sdif);
494 if (!dev) {
495 rcu_read_unlock();
496 kfree_skb(skb);
497 return -ENODEV;
498 }
499 } else {
500 dev = skb->dev;
501 }
502
503 hdr = ipv6_hdr(skb);
504 deliver = ipv6_chk_mcast_addr(dev, &hdr->daddr, NULL);
505 if (sdif)
506 rcu_read_unlock();
507
508 #ifdef CONFIG_IPV6_MROUTE
509 /*
510 * IPv6 multicast router mode is now supported ;)
511 */
512 if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
513 !(ipv6_addr_type(&hdr->daddr) &
514 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
515 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
516 /*
517 * Okay, we try to forward - split and duplicate
518 * packets.
519 */
520 struct sk_buff *skb2;
521 struct inet6_skb_parm *opt = IP6CB(skb);
522
523 /* Check for MLD */
524 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
525 /* Check if this is a mld message */
526 u8 nexthdr = hdr->nexthdr;
527 __be16 frag_off;
528 int offset;
529
530 /* Check if the value of Router Alert
531 * is for MLD (0x0000).
532 */
533 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
534 deliver = false;
535
536 if (!ipv6_ext_hdr(nexthdr)) {
537 /* BUG */
538 goto out;
539 }
540 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
541 &nexthdr, &frag_off);
542 if (offset < 0)
543 goto out;
544
545 if (ipv6_is_mld(skb, nexthdr, offset))
546 deliver = true;
547
548 goto out;
549 }
550 /* unknown RA - process it normally */
551 }
552
553 if (deliver)
554 skb2 = skb_clone(skb, GFP_ATOMIC);
555 else {
556 skb2 = skb;
557 skb = NULL;
558 }
559
560 if (skb2) {
561 ip6_mr_input(skb2);
562 }
563 }
564 out:
565 #endif
566 if (likely(deliver))
567 ip6_input(skb);
568 else {
569 /* discard */
570 kfree_skb(skb);
571 }
572
573 return 0;
574 }
575