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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * The Internet Protocol (IP) module.
8 *
9 * Authors: Ross Biro
10 * Fred N. van Kempen, <[email protected]>
11 * Donald Becker, <[email protected]>
12 * Alan Cox, <[email protected]>
13 * Richard Underwood
14 * Stefan Becker, <[email protected]>
15 * Jorge Cwik, <[email protected]>
16 * Arnt Gulbrandsen, <[email protected]>
17 *
18 * Fixes:
19 * Alan Cox : Commented a couple of minor bits of surplus code
20 * Alan Cox : Undefining IP_FORWARD doesn't include the code
21 * (just stops a compiler warning).
22 * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes
23 * are junked rather than corrupting things.
24 * Alan Cox : Frames to bad broadcast subnets are dumped
25 * We used to process them non broadcast and
26 * boy could that cause havoc.
27 * Alan Cox : ip_forward sets the free flag on the
28 * new frame it queues. Still crap because
29 * it copies the frame but at least it
30 * doesn't eat memory too.
31 * Alan Cox : Generic queue code and memory fixes.
32 * Fred Van Kempen : IP fragment support (borrowed from NET2E)
33 * Gerhard Koerting: Forward fragmented frames correctly.
34 * Gerhard Koerting: Fixes to my fix of the above 8-).
35 * Gerhard Koerting: IP interface addressing fix.
36 * Linus Torvalds : More robustness checks
37 * Alan Cox : Even more checks: Still not as robust as it ought to be
38 * Alan Cox : Save IP header pointer for later
39 * Alan Cox : ip option setting
40 * Alan Cox : Use ip_tos/ip_ttl settings
41 * Alan Cox : Fragmentation bogosity removed
42 * (Thanks to [email protected])
43 * Dmitry Gorodchanin : Send of a raw packet crash fix.
44 * Alan Cox : Silly ip bug when an overlength
45 * fragment turns up. Now frees the
46 * queue.
47 * Linus Torvalds/ : Memory leakage on fragmentation
48 * Alan Cox : handling.
49 * Gerhard Koerting: Forwarding uses IP priority hints
50 * Teemu Rantanen : Fragment problems.
51 * Alan Cox : General cleanup, comments and reformat
52 * Alan Cox : SNMP statistics
53 * Alan Cox : BSD address rule semantics. Also see
54 * UDP as there is a nasty checksum issue
55 * if you do things the wrong way.
56 * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file
57 * Alan Cox : IP options adjust sk->priority.
58 * Pedro Roque : Fix mtu/length error in ip_forward.
59 * Alan Cox : Avoid ip_chk_addr when possible.
60 * Richard Underwood : IP multicasting.
61 * Alan Cox : Cleaned up multicast handlers.
62 * Alan Cox : RAW sockets demultiplex in the BSD style.
63 * Gunther Mayer : Fix the SNMP reporting typo
64 * Alan Cox : Always in group 224.0.0.1
65 * Pauline Middelink : Fast ip_checksum update when forwarding
66 * Masquerading support.
67 * Alan Cox : Multicast loopback error for 224.0.0.1
68 * Alan Cox : IP_MULTICAST_LOOP option.
69 * Alan Cox : Use notifiers.
70 * Bjorn Ekwall : Removed ip_csum (from slhc.c too)
71 * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!)
72 * Stefan Becker : Send out ICMP HOST REDIRECT
73 * Arnt Gulbrandsen : ip_build_xmit
74 * Alan Cox : Per socket routing cache
75 * Alan Cox : Fixed routing cache, added header cache.
76 * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it.
77 * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net.
78 * Alan Cox : Incoming IP option handling.
79 * Alan Cox : Set saddr on raw output frames as per BSD.
80 * Alan Cox : Stopped broadcast source route explosions.
81 * Alan Cox : Can disable source routing
82 * Takeshi Sone : Masquerading didn't work.
83 * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible.
84 * Alan Cox : Memory leaks, tramples, misc debugging.
85 * Alan Cox : Fixed multicast (by popular demand 8))
86 * Alan Cox : Fixed forwarding (by even more popular demand 8))
87 * Alan Cox : Fixed SNMP statistics [I think]
88 * Gerhard Koerting : IP fragmentation forwarding fix
89 * Alan Cox : Device lock against page fault.
90 * Alan Cox : IP_HDRINCL facility.
91 * Werner Almesberger : Zero fragment bug
92 * Alan Cox : RAW IP frame length bug
93 * Alan Cox : Outgoing firewall on build_xmit
94 * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel
95 * Alan Cox : Multicast routing hooks
96 * Jos Vos : Do accounting *before* call_in_firewall
97 * Willy Konynenberg : Transparent proxying support
98 *
99 * To Fix:
100 * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient
101 * and could be made very efficient with the addition of some virtual memory hacks to permit
102 * the allocation of a buffer that can then be 'grown' by twiddling page tables.
103 * Output fragmentation wants updating along with the buffer management to use a single
104 * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet
105 * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause
106 * fragmentation anyway.
107 */
108
109#define pr_fmt(fmt) "IPv4: " fmt
110
111#include <linux/module.h>
112#include <linux/types.h>
113#include <linux/kernel.h>
114#include <linux/string.h>
115#include <linux/errno.h>
116#include <linux/slab.h>
117
118#include <linux/net.h>
119#include <linux/socket.h>
120#include <linux/sockios.h>
121#include <linux/in.h>
122#include <linux/inet.h>
123#include <linux/inetdevice.h>
124#include <linux/netdevice.h>
125#include <linux/etherdevice.h>
126#include <linux/indirect_call_wrapper.h>
127
128#include <net/snmp.h>
129#include <net/ip.h>
130#include <net/protocol.h>
131#include <net/route.h>
132#include <linux/skbuff.h>
133#include <net/sock.h>
134#include <net/arp.h>
135#include <net/icmp.h>
136#include <net/raw.h>
137#include <net/checksum.h>
138#include <net/inet_ecn.h>
139#include <linux/netfilter_ipv4.h>
140#include <net/xfrm.h>
141#include <linux/mroute.h>
142#include <linux/netlink.h>
143#include <net/dst_metadata.h>
144#include <net/udp.h>
145#include <net/tcp.h>
146
147/*
148 * Process Router Attention IP option (RFC 2113)
149 */
150bool ip_call_ra_chain(struct sk_buff *skb)
151{
152 struct ip_ra_chain *ra;
153 u8 protocol = ip_hdr(skb)->protocol;
154 struct sock *last = NULL;
155 struct net_device *dev = skb->dev;
156 struct net *net = dev_net(dev);
157
158 for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) {
159 struct sock *sk = ra->sk;
160
161 /* If socket is bound to an interface, only report
162 * the packet if it came from that interface.
163 */
164 if (sk && inet_sk(sk)->inet_num == protocol &&
165 (!sk->sk_bound_dev_if ||
166 sk->sk_bound_dev_if == dev->ifindex)) {
167 if (ip_is_fragment(ip_hdr(skb))) {
168 if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN))
169 return true;
170 }
171 if (last) {
172 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
173 if (skb2)
174 raw_rcv(last, skb2);
175 }
176 last = sk;
177 }
178 }
179
180 if (last) {
181 raw_rcv(last, skb);
182 return true;
183 }
184 return false;
185}
186
187INDIRECT_CALLABLE_DECLARE(int udp_rcv(struct sk_buff *));
188INDIRECT_CALLABLE_DECLARE(int tcp_v4_rcv(struct sk_buff *));
189void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol)
190{
191 const struct net_protocol *ipprot;
192 int raw, ret;
193
194resubmit:
195 raw = raw_local_deliver(skb, protocol);
196
197 ipprot = rcu_dereference(inet_protos[protocol]);
198 if (ipprot) {
199 if (!ipprot->no_policy) {
200 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
201 kfree_skb_reason(skb,
202 SKB_DROP_REASON_XFRM_POLICY);
203 return;
204 }
205 nf_reset_ct(skb);
206 }
207 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv,
208 skb);
209 if (ret < 0) {
210 protocol = -ret;
211 goto resubmit;
212 }
213 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
214 } else {
215 if (!raw) {
216 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
217 __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS);
218 icmp_send(skb, ICMP_DEST_UNREACH,
219 ICMP_PROT_UNREACH, 0);
220 }
221 kfree_skb_reason(skb, SKB_DROP_REASON_IP_NOPROTO);
222 } else {
223 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
224 consume_skb(skb);
225 }
226 }
227}
228
229static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
230{
231 if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) {
232 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
233 kfree_skb_reason(skb, SKB_DROP_REASON_NOMEM);
234 return 0;
235 }
236
237 skb_clear_delivery_time(skb);
238 __skb_pull(skb, skb_network_header_len(skb));
239
240 rcu_read_lock();
241 ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol);
242 rcu_read_unlock();
243
244 return 0;
245}
246
247/*
248 * Deliver IP Packets to the higher protocol layers.
249 */
250int ip_local_deliver(struct sk_buff *skb)
251{
252 /*
253 * Reassemble IP fragments.
254 */
255 struct net *net = dev_net(skb->dev);
256
257 if (ip_is_fragment(ip_hdr(skb))) {
258 if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER))
259 return 0;
260 }
261
262 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN,
263 net, NULL, skb, skb->dev, NULL,
264 ip_local_deliver_finish);
265}
266EXPORT_SYMBOL(ip_local_deliver);
267
268static inline enum skb_drop_reason
269ip_rcv_options(struct sk_buff *skb, struct net_device *dev)
270{
271 const struct iphdr *iph;
272 struct ip_options *opt;
273
274 /* It looks as overkill, because not all
275 IP options require packet mangling.
276 But it is the easiest for now, especially taking
277 into account that combination of IP options
278 and running sniffer is extremely rare condition.
279 --ANK (980813)
280 */
281 if (skb_cow(skb, skb_headroom(skb))) {
282 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS);
283 return SKB_DROP_REASON_NOMEM;
284 }
285
286 iph = ip_hdr(skb);
287 opt = &(IPCB(skb)->opt);
288 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
289
290 if (ip_options_compile(dev_net(dev), opt, skb)) {
291 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
292 return SKB_DROP_REASON_IP_INHDR;
293 }
294
295 if (unlikely(opt->srr)) {
296 struct in_device *in_dev = __in_dev_get_rcu(dev);
297
298 if (in_dev) {
299 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
300 if (IN_DEV_LOG_MARTIANS(in_dev))
301 net_info_ratelimited("source route option %pI4 -> %pI4\n",
302 &iph->saddr,
303 &iph->daddr);
304 return SKB_DROP_REASON_NOT_SPECIFIED;
305 }
306 }
307
308 if (ip_options_rcv_srr(skb, dev))
309 return SKB_DROP_REASON_NOT_SPECIFIED;
310 }
311
312 return SKB_NOT_DROPPED_YET;
313}
314
315static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph,
316 const struct sk_buff *hint)
317{
318 return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr &&
319 ip_hdr(hint)->tos == iph->tos;
320}
321
322static int tcp_v4_early_demux(struct sk_buff *skb)
323{
324 struct net *net = dev_net_rcu(skb->dev);
325 const struct iphdr *iph;
326 const struct tcphdr *th;
327 struct sock *sk;
328
329 if (skb->pkt_type != PACKET_HOST)
330 return 0;
331
332 if (!pskb_may_pull(skb, skb_transport_offset(skb) +
333 sizeof(struct tcphdr)))
334 return 0;
335
336 iph = ip_hdr(skb);
337 th = tcp_hdr(skb);
338
339 if (th->doff < sizeof(struct tcphdr) / 4)
340 return 0;
341
342 sk = __inet_lookup_established(net, iph->saddr, th->source,
343 iph->daddr, ntohs(th->dest),
344 skb->skb_iif, inet_sdif(skb));
345 if (sk) {
346 skb->sk = sk;
347 skb->destructor = sock_edemux;
348 if (sk_fullsock(sk)) {
349 struct dst_entry *dst = rcu_dereference(sk->sk_rx_dst);
350
351 if (dst)
352 dst = dst_check(dst, 0);
353 if (dst &&
354 sk->sk_rx_dst_ifindex == skb->skb_iif)
355 skb_dst_set_noref(skb, dst);
356 }
357 }
358 return 0;
359}
360
361static int ip_rcv_finish_core(struct net *net,
362 struct sk_buff *skb, struct net_device *dev,
363 const struct sk_buff *hint)
364{
365 const struct iphdr *iph = ip_hdr(skb);
366 struct rtable *rt;
367 int drop_reason;
368
369 if (ip_can_use_hint(skb, iph, hint)) {
370 drop_reason = ip_route_use_hint(skb, iph->daddr, iph->saddr,
371 ip4h_dscp(iph), dev, hint);
372 if (unlikely(drop_reason))
373 goto drop_error;
374 }
375
376 if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
377 !skb_dst(skb) &&
378 !skb->sk &&
379 !ip_is_fragment(iph)) {
380 switch (iph->protocol) {
381 case IPPROTO_TCP:
382 if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) {
383 tcp_v4_early_demux(skb);
384
385 /* must reload iph, skb->head might have changed */
386 iph = ip_hdr(skb);
387 }
388 break;
389 case IPPROTO_UDP:
390 if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) {
391 drop_reason = udp_v4_early_demux(skb);
392 if (unlikely(drop_reason))
393 goto drop_error;
394
395 /* must reload iph, skb->head might have changed */
396 iph = ip_hdr(skb);
397 }
398 break;
399 }
400 }
401
402 /*
403 * Initialise the virtual path cache for the packet. It describes
404 * how the packet travels inside Linux networking.
405 */
406 if (!skb_valid_dst(skb)) {
407 drop_reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
408 ip4h_dscp(iph), dev);
409 if (unlikely(drop_reason))
410 goto drop_error;
411 } else {
412 struct in_device *in_dev = __in_dev_get_rcu(dev);
413
414 if (in_dev && IN_DEV_ORCONF(in_dev, NOPOLICY))
415 IPCB(skb)->flags |= IPSKB_NOPOLICY;
416 }
417
418#ifdef CONFIG_IP_ROUTE_CLASSID
419 if (unlikely(skb_dst(skb)->tclassid)) {
420 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
421 u32 idx = skb_dst(skb)->tclassid;
422 st[idx&0xFF].o_packets++;
423 st[idx&0xFF].o_bytes += skb->len;
424 st[(idx>>16)&0xFF].i_packets++;
425 st[(idx>>16)&0xFF].i_bytes += skb->len;
426 }
427#endif
428
429 if (iph->ihl > 5) {
430 drop_reason = ip_rcv_options(skb, dev);
431 if (drop_reason)
432 goto drop;
433 }
434
435 rt = skb_rtable(skb);
436 if (rt->rt_type == RTN_MULTICAST) {
437 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len);
438 } else if (rt->rt_type == RTN_BROADCAST) {
439 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len);
440 } else if (skb->pkt_type == PACKET_BROADCAST ||
441 skb->pkt_type == PACKET_MULTICAST) {
442 struct in_device *in_dev = __in_dev_get_rcu(dev);
443
444 /* RFC 1122 3.3.6:
445 *
446 * When a host sends a datagram to a link-layer broadcast
447 * address, the IP destination address MUST be a legal IP
448 * broadcast or IP multicast address.
449 *
450 * A host SHOULD silently discard a datagram that is received
451 * via a link-layer broadcast (see Section 2.4) but does not
452 * specify an IP multicast or broadcast destination address.
453 *
454 * This doesn't explicitly say L2 *broadcast*, but broadcast is
455 * in a way a form of multicast and the most common use case for
456 * this is 802.11 protecting against cross-station spoofing (the
457 * so-called "hole-196" attack) so do it for both.
458 */
459 if (in_dev &&
460 IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) {
461 drop_reason = SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST;
462 goto drop;
463 }
464 }
465
466 return NET_RX_SUCCESS;
467
468drop:
469 kfree_skb_reason(skb, drop_reason);
470 return NET_RX_DROP;
471
472drop_error:
473 if (drop_reason == SKB_DROP_REASON_IP_RPFILTER)
474 __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
475 goto drop;
476}
477
478static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
479{
480 struct net_device *dev = skb->dev;
481 int ret;
482
483 /* if ingress device is enslaved to an L3 master device pass the
484 * skb to its handler for processing
485 */
486 skb = l3mdev_ip_rcv(skb);
487 if (!skb)
488 return NET_RX_SUCCESS;
489
490 ret = ip_rcv_finish_core(net, skb, dev, NULL);
491 if (ret != NET_RX_DROP)
492 ret = dst_input(skb);
493 return ret;
494}
495
496/*
497 * Main IP Receive routine.
498 */
499static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
500{
501 const struct iphdr *iph;
502 int drop_reason;
503 u32 len;
504
505 /* When the interface is in promisc. mode, drop all the crap
506 * that it receives, do not try to analyse it.
507 */
508 if (skb->pkt_type == PACKET_OTHERHOST) {
509 dev_core_stats_rx_otherhost_dropped_inc(skb->dev);
510 drop_reason = SKB_DROP_REASON_OTHERHOST;
511 goto drop;
512 }
513
514 __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
515
516 skb = skb_share_check(skb, GFP_ATOMIC);
517 if (!skb) {
518 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
519 goto out;
520 }
521
522 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
523 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
524 goto inhdr_error;
525
526 iph = ip_hdr(skb);
527
528 /*
529 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
530 *
531 * Is the datagram acceptable?
532 *
533 * 1. Length at least the size of an ip header
534 * 2. Version of 4
535 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
536 * 4. Doesn't have a bogus length
537 */
538
539 if (iph->ihl < 5 || iph->version != 4)
540 goto inhdr_error;
541
542 BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
543 BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
544 BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
545 __IP_ADD_STATS(net,
546 IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
547 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
548
549 if (!pskb_may_pull(skb, iph->ihl*4))
550 goto inhdr_error;
551
552 iph = ip_hdr(skb);
553
554 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
555 goto csum_error;
556
557 len = iph_totlen(skb, iph);
558 if (skb->len < len) {
559 drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
560 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
561 goto drop;
562 } else if (len < (iph->ihl*4))
563 goto inhdr_error;
564
565 /* Our transport medium may have padded the buffer out. Now we know it
566 * is IP we can trim to the true length of the frame.
567 * Note this now means skb->len holds ntohs(iph->tot_len).
568 */
569 if (pskb_trim_rcsum(skb, len)) {
570 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
571 goto drop;
572 }
573
574 iph = ip_hdr(skb);
575 skb->transport_header = skb->network_header + iph->ihl*4;
576
577 /* Remove any debris in the socket control block */
578 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
579 IPCB(skb)->iif = skb->skb_iif;
580
581 /* Must drop socket now because of tproxy. */
582 if (!skb_sk_is_prefetched(skb))
583 skb_orphan(skb);
584
585 return skb;
586
587csum_error:
588 drop_reason = SKB_DROP_REASON_IP_CSUM;
589 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
590inhdr_error:
591 if (drop_reason == SKB_DROP_REASON_NOT_SPECIFIED)
592 drop_reason = SKB_DROP_REASON_IP_INHDR;
593 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
594drop:
595 kfree_skb_reason(skb, drop_reason);
596out:
597 return NULL;
598}
599
600/*
601 * IP receive entry point
602 */
603int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
604 struct net_device *orig_dev)
605{
606 struct net *net = dev_net(dev);
607
608 skb = ip_rcv_core(skb, net);
609 if (skb == NULL)
610 return NET_RX_DROP;
611
612 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
613 net, NULL, skb, dev, NULL,
614 ip_rcv_finish);
615}
616
617static void ip_sublist_rcv_finish(struct list_head *head)
618{
619 struct sk_buff *skb, *next;
620
621 list_for_each_entry_safe(skb, next, head, list) {
622 skb_list_del_init(skb);
623 dst_input(skb);
624 }
625}
626
627static struct sk_buff *ip_extract_route_hint(const struct net *net,
628 struct sk_buff *skb)
629{
630 const struct iphdr *iph = ip_hdr(skb);
631
632 if (fib4_has_custom_rules(net) ||
633 ipv4_is_lbcast(iph->daddr) ||
634 ipv4_is_zeronet(iph->daddr) ||
635 IPCB(skb)->flags & IPSKB_MULTIPATH)
636 return NULL;
637
638 return skb;
639}
640
641static void ip_list_rcv_finish(struct net *net, struct list_head *head)
642{
643 struct sk_buff *skb, *next, *hint = NULL;
644 struct dst_entry *curr_dst = NULL;
645 LIST_HEAD(sublist);
646
647 list_for_each_entry_safe(skb, next, head, list) {
648 struct net_device *dev = skb->dev;
649 struct dst_entry *dst;
650
651 skb_list_del_init(skb);
652 /* if ingress device is enslaved to an L3 master device pass the
653 * skb to its handler for processing
654 */
655 skb = l3mdev_ip_rcv(skb);
656 if (!skb)
657 continue;
658 if (ip_rcv_finish_core(net, skb, dev, hint) == NET_RX_DROP)
659 continue;
660
661 dst = skb_dst(skb);
662 if (curr_dst != dst) {
663 hint = ip_extract_route_hint(net, skb);
664
665 /* dispatch old sublist */
666 if (!list_empty(&sublist))
667 ip_sublist_rcv_finish(&sublist);
668 /* start new sublist */
669 INIT_LIST_HEAD(&sublist);
670 curr_dst = dst;
671 }
672 list_add_tail(&skb->list, &sublist);
673 }
674 /* dispatch final sublist */
675 ip_sublist_rcv_finish(&sublist);
676}
677
678static void ip_sublist_rcv(struct list_head *head, struct net_device *dev,
679 struct net *net)
680{
681 NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL,
682 head, dev, NULL, ip_rcv_finish);
683 ip_list_rcv_finish(net, head);
684}
685
686/* Receive a list of IP packets */
687void ip_list_rcv(struct list_head *head, struct packet_type *pt,
688 struct net_device *orig_dev)
689{
690 struct net_device *curr_dev = NULL;
691 struct net *curr_net = NULL;
692 struct sk_buff *skb, *next;
693 LIST_HEAD(sublist);
694
695 list_for_each_entry_safe(skb, next, head, list) {
696 struct net_device *dev = skb->dev;
697 struct net *net = dev_net(dev);
698
699 skb_list_del_init(skb);
700 skb = ip_rcv_core(skb, net);
701 if (skb == NULL)
702 continue;
703
704 if (curr_dev != dev || curr_net != net) {
705 /* dispatch old sublist */
706 if (!list_empty(&sublist))
707 ip_sublist_rcv(&sublist, curr_dev, curr_net);
708 /* start new sublist */
709 INIT_LIST_HEAD(&sublist);
710 curr_dev = dev;
711 curr_net = net;
712 }
713 list_add_tail(&skb->list, &sublist);
714 }
715 /* dispatch final sublist */
716 if (!list_empty(&sublist))
717 ip_sublist_rcv(&sublist, curr_dev, curr_net);
718}