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(a1: &ipv6_hdr(skb: hint)->daddr, a2: &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(nskb: skb, oskb: 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(head: &sublist))
137 ip6_sublist_rcv_finish(head: &sublist);
138 /* start new sublist */
139 INIT_LIST_HEAD(list: &sublist);
140 curr_dst = dst;
141 }
142 list_add_tail(new: &skb->list, head: &sublist);
143 }
144 /* dispatch final sublist */
145 ip6_sublist_rcv_finish(head: &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(dev: skb->dev);
158 kfree_skb_reason(skb, reason: SKB_DROP_REASON_OTHERHOST);
159 return NULL;
160 }
161
162 rcu_read_lock();
163
164 idev = __in6_dev_get(dev: 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), c: 0, n: 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) ?
191 ip6_dst_idev(dst: skb_dst(skb))->dev->ifindex :
192 dev->ifindex;
193
194 if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
195 goto err;
196
197 hdr = ipv6_hdr(skb);
198
199 if (hdr->version != 6) {
200 SKB_DR_SET(reason, UNHANDLED_PROTO);
201 goto err;
202 }
203
204 __IP6_ADD_STATS(net, idev,
205 IPSTATS_MIB_NOECTPKTS +
206 (ipv6_get_dsfield(hdr) & INET_ECN_MASK),
207 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
208 /*
209 * RFC4291 2.5.3
210 * The loopback address must not be used as the source address in IPv6
211 * packets that are sent outside of a single node. [..]
212 * A packet received on an interface with a destination address
213 * of loopback must be dropped.
214 */
215 if ((ipv6_addr_loopback(a: &hdr->saddr) ||
216 ipv6_addr_loopback(a: &hdr->daddr)) &&
217 !(dev->flags & IFF_LOOPBACK) &&
218 !netif_is_l3_master(dev))
219 goto err;
220
221 /* RFC4291 Errata ID: 3480
222 * Interface-Local scope spans only a single interface on a
223 * node and is useful only for loopback transmission of
224 * multicast. Packets with interface-local scope received
225 * from another node must be discarded.
226 */
227 if (!(skb->pkt_type == PACKET_LOOPBACK ||
228 dev->flags & IFF_LOOPBACK) &&
229 ipv6_addr_is_multicast(addr: &hdr->daddr) &&
230 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
231 goto err;
232
233 /* If enabled, drop unicast packets that were encapsulated in link-layer
234 * multicast or broadcast to protected against the so-called "hole-196"
235 * attack in 802.11 wireless.
236 */
237 if (!ipv6_addr_is_multicast(addr: &hdr->daddr) &&
238 (skb->pkt_type == PACKET_BROADCAST ||
239 skb->pkt_type == PACKET_MULTICAST) &&
240 READ_ONCE(idev->cnf.drop_unicast_in_l2_multicast)) {
241 SKB_DR_SET(reason, UNICAST_IN_L2_MULTICAST);
242 goto err;
243 }
244
245 /* RFC4291 2.7
246 * Nodes must not originate a packet to a multicast address whose scope
247 * field contains the reserved value 0; if such a packet is received, it
248 * must be silently dropped.
249 */
250 if (ipv6_addr_is_multicast(addr: &hdr->daddr) &&
251 IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
252 goto err;
253
254 /*
255 * RFC4291 2.7
256 * Multicast addresses must not be used as source addresses in IPv6
257 * packets or appear in any Routing header.
258 */
259 if (ipv6_addr_is_multicast(addr: &hdr->saddr))
260 goto err;
261
262 skb->transport_header = skb->network_header + sizeof(*hdr);
263 IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
264
265 pkt_len = ntohs(hdr->payload_len);
266
267 /* pkt_len may be zero if Jumbo payload option is present */
268 if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
269 if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
270 __IP6_INC_STATS(net,
271 idev, IPSTATS_MIB_INTRUNCATEDPKTS);
272 SKB_DR_SET(reason, PKT_TOO_SMALL);
273 goto drop;
274 }
275 if (pskb_trim_rcsum(skb, len: pkt_len + sizeof(struct ipv6hdr)))
276 goto err;
277 hdr = ipv6_hdr(skb);
278 }
279
280 if (hdr->nexthdr == NEXTHDR_HOP) {
281 if (ipv6_parse_hopopts(skb) < 0) {
282 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
283 rcu_read_unlock();
284 return NULL;
285 }
286 }
287
288 rcu_read_unlock();
289
290 /* Must drop socket now because of tproxy. */
291 if (!skb_sk_is_prefetched(skb))
292 skb_orphan(skb);
293
294 return skb;
295err:
296 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
297 SKB_DR_OR(reason, IP_INHDR);
298drop:
299 rcu_read_unlock();
300 kfree_skb_reason(skb, reason);
301 return NULL;
302}
303
304int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
305{
306 struct net *net = dev_net(dev: skb->dev);
307
308 skb = ip6_rcv_core(skb, dev, net);
309 if (skb == NULL)
310 return NET_RX_DROP;
311 return NF_HOOK(pf: NFPROTO_IPV6, hook: NF_INET_PRE_ROUTING,
312 net, NULL, skb, in: dev, NULL,
313 okfn: ip6_rcv_finish);
314}
315
316static void ip6_sublist_rcv(struct list_head *head, struct net_device *dev,
317 struct net *net)
318{
319 NF_HOOK_LIST(pf: NFPROTO_IPV6, hook: NF_INET_PRE_ROUTING, net, NULL,
320 head, in: dev, NULL, okfn: ip6_rcv_finish);
321 ip6_list_rcv_finish(net, NULL, head);
322}
323
324/* Receive a list of IPv6 packets */
325void ipv6_list_rcv(struct list_head *head, struct packet_type *pt,
326 struct net_device *orig_dev)
327{
328 struct net_device *curr_dev = NULL;
329 struct net *curr_net = NULL;
330 struct sk_buff *skb, *next;
331 LIST_HEAD(sublist);
332
333 list_for_each_entry_safe(skb, next, head, list) {
334 struct net_device *dev = skb->dev;
335 struct net *net = dev_net(dev);
336
337 skb_list_del_init(skb);
338 skb = ip6_rcv_core(skb, dev, net);
339 if (skb == NULL)
340 continue;
341
342 if (curr_dev != dev || curr_net != net) {
343 /* dispatch old sublist */
344 if (!list_empty(head: &sublist))
345 ip6_sublist_rcv(head: &sublist, dev: curr_dev, net: curr_net);
346 /* start new sublist */
347 INIT_LIST_HEAD(list: &sublist);
348 curr_dev = dev;
349 curr_net = net;
350 }
351 list_add_tail(new: &skb->list, head: &sublist);
352 }
353 /* dispatch final sublist */
354 if (!list_empty(head: &sublist))
355 ip6_sublist_rcv(head: &sublist, dev: curr_dev, net: curr_net);
356}
357
358INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *));
359
360/*
361 * Deliver the packet to the host
362 */
363void ip6_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int nexthdr,
364 bool have_final)
365{
366 const struct inet6_protocol *ipprot;
367 struct inet6_dev *idev;
368 unsigned int nhoff;
369 SKB_DR(reason);
370 bool raw;
371
372 /*
373 * Parse extension headers
374 */
375
376resubmit:
377 idev = ip6_dst_idev(dst: skb_dst(skb));
378 nhoff = IP6CB(skb)->nhoff;
379 if (!have_final) {
380 if (!pskb_pull(skb, len: skb_transport_offset(skb)))
381 goto discard;
382 nexthdr = skb_network_header(skb)[nhoff];
383 }
384
385resubmit_final:
386 raw = raw6_local_deliver(skb, nexthdr);
387 ipprot = rcu_dereference(inet6_protos[nexthdr]);
388 if (ipprot) {
389 int ret;
390
391 if (have_final) {
392 if (!(ipprot->flags & INET6_PROTO_FINAL)) {
393 /* Once we've seen a final protocol don't
394 * allow encapsulation on any non-final
395 * ones. This allows foo in UDP encapsulation
396 * to work.
397 */
398 goto discard;
399 }
400 } else if (ipprot->flags & INET6_PROTO_FINAL) {
401 const struct ipv6hdr *hdr;
402 int sdif = inet6_sdif(skb);
403 struct net_device *dev;
404
405 /* Only do this once for first final protocol */
406 have_final = true;
407
408
409 skb_postpull_rcsum(skb, start: skb_network_header(skb),
410 len: skb_network_header_len(skb));
411 hdr = ipv6_hdr(skb);
412
413 /* skb->dev passed may be master dev for vrfs. */
414 if (sdif) {
415 dev = dev_get_by_index_rcu(net, ifindex: sdif);
416 if (!dev)
417 goto discard;
418 } else {
419 dev = skb->dev;
420 }
421
422 if (ipv6_addr_is_multicast(addr: &hdr->daddr) &&
423 !ipv6_chk_mcast_addr(dev, group: &hdr->daddr,
424 src_addr: &hdr->saddr) &&
425 !ipv6_is_mld(skb, nexthdr, offset: skb_network_header_len(skb))) {
426 SKB_DR_SET(reason, IP_INADDRERRORS);
427 goto discard;
428 }
429 }
430 if (!(ipprot->flags & INET6_PROTO_NOPOLICY)) {
431 if (!xfrm6_policy_check(NULL, dir: XFRM_POLICY_IN, skb)) {
432 SKB_DR_SET(reason, XFRM_POLICY);
433 goto discard;
434 }
435 nf_reset_ct(skb);
436 }
437
438 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v6_rcv, udpv6_rcv,
439 skb);
440 if (ret > 0) {
441 if (ipprot->flags & INET6_PROTO_FINAL) {
442 /* Not an extension header, most likely UDP
443 * encapsulation. Use return value as nexthdr
444 * protocol not nhoff (which presumably is
445 * not set by handler).
446 */
447 nexthdr = ret;
448 goto resubmit_final;
449 } else {
450 goto resubmit;
451 }
452 } else if (ret == 0) {
453 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
454 }
455 } else {
456 if (!raw) {
457 if (xfrm6_policy_check(NULL, dir: XFRM_POLICY_IN, skb)) {
458 __IP6_INC_STATS(net, idev,
459 IPSTATS_MIB_INUNKNOWNPROTOS);
460 icmpv6_send(skb, ICMPV6_PARAMPROB,
461 ICMPV6_UNK_NEXTHDR, info: nhoff);
462 SKB_DR_SET(reason, IP_NOPROTO);
463 } else {
464 SKB_DR_SET(reason, XFRM_POLICY);
465 }
466 kfree_skb_reason(skb, reason);
467 } else {
468 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
469 consume_skb(skb);
470 }
471 }
472 return;
473
474discard:
475 __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
476 kfree_skb_reason(skb, reason);
477}
478
479static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
480{
481 if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) {
482 __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
483 IPSTATS_MIB_INDISCARDS);
484 kfree_skb_reason(skb, reason: SKB_DROP_REASON_NOMEM);
485 return 0;
486 }
487
488 skb_clear_delivery_time(skb);
489 ip6_protocol_deliver_rcu(net, skb, nexthdr: 0, have_final: false);
490
491 return 0;
492}
493
494
495int ip6_input(struct sk_buff *skb)
496{
497 int res;
498
499 rcu_read_lock();
500 res = NF_HOOK(pf: NFPROTO_IPV6, hook: NF_INET_LOCAL_IN,
501 net: dev_net_rcu(dev: skb->dev), NULL, skb, in: skb->dev, NULL,
502 okfn: ip6_input_finish);
503 rcu_read_unlock();
504
505 return res;
506}
507EXPORT_SYMBOL_GPL(ip6_input);
508
509int ip6_mc_input(struct sk_buff *skb)
510{
511 struct net_device *dev = skb->dev;
512 int sdif = inet6_sdif(skb);
513 const struct ipv6hdr *hdr;
514 bool deliver;
515
516 __IP6_UPD_PO_STATS(skb_dst_dev_net_rcu(skb),
517 __in6_dev_get_safely(dev), IPSTATS_MIB_INMCAST,
518 skb->len);
519
520 /* skb->dev passed may be master dev for vrfs. */
521 if (sdif) {
522 dev = dev_get_by_index_rcu(net: dev_net_rcu(dev), ifindex: sdif);
523 if (!dev) {
524 kfree_skb(skb);
525 return -ENODEV;
526 }
527 }
528
529 hdr = ipv6_hdr(skb);
530 deliver = ipv6_chk_mcast_addr(dev, group: &hdr->daddr, NULL);
531
532#ifdef CONFIG_IPV6_MROUTE
533 /*
534 * IPv6 multicast router mode is now supported ;)
535 */
536 if (atomic_read(&dev_net_rcu(skb->dev)->ipv6.devconf_all->mc_forwarding) &&
537 !(ipv6_addr_type(&hdr->daddr) &
538 (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
539 likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
540 /*
541 * Okay, we try to forward - split and duplicate
542 * packets.
543 */
544 struct sk_buff *skb2;
545 struct inet6_skb_parm *opt = IP6CB(skb);
546
547 /* Check for MLD */
548 if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
549 /* Check if this is a mld message */
550 u8 nexthdr = hdr->nexthdr;
551 __be16 frag_off;
552 int offset;
553
554 /* Check if the value of Router Alert
555 * is for MLD (0x0000).
556 */
557 if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
558 deliver = false;
559
560 if (!ipv6_ext_hdr(nexthdr)) {
561 /* BUG */
562 goto out;
563 }
564 offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
565 &nexthdr, &frag_off);
566 if (offset < 0)
567 goto out;
568
569 if (ipv6_is_mld(skb, nexthdr, offset))
570 deliver = true;
571
572 goto out;
573 }
574 /* unknown RA - process it normally */
575 }
576
577 if (deliver) {
578 skb2 = skb_clone(skb, GFP_ATOMIC);
579 } else {
580 skb2 = skb;
581 skb = NULL;
582 }
583
584 if (skb2)
585 ip6_mr_input(skb2);
586 }
587out:
588#endif
589 if (likely(deliver)) {
590 ip6_input(skb);
591 } else {
592 /* discard */
593 kfree_skb(skb);
594 }
595
596 return 0;
597}
598