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, <waltje@uWalt.NL.Mugnet.ORG>
11 * Donald Becker, <becker@super.org>
12 * Alan Cox, <alan@lxorguk.ukuu.org.uk>
13 * Richard Underwood
14 * Stefan Becker, <stefanb@yello.ping.de>
15 * Jorge Cwik, <jorge@laser.satlink.net>
16 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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 Mark.Bush@prg.ox.ac.uk)
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
145 /*
146 * Process Router Attention IP option (RFC 2113)
147 */
ip_call_ra_chain(struct sk_buff * skb)148 bool ip_call_ra_chain(struct sk_buff *skb)
149 {
150 struct ip_ra_chain *ra;
151 u8 protocol = ip_hdr(skb)->protocol;
152 struct sock *last = NULL;
153 struct net_device *dev = skb->dev;
154 struct net *net = dev_net(dev);
155
156 for (ra = rcu_dereference(net->ipv4.ra_chain); ra; ra = rcu_dereference(ra->next)) {
157 struct sock *sk = ra->sk;
158
159 /* If socket is bound to an interface, only report
160 * the packet if it came from that interface.
161 */
162 if (sk && inet_sk(sk)->inet_num == protocol &&
163 (!sk->sk_bound_dev_if ||
164 sk->sk_bound_dev_if == dev->ifindex)) {
165 if (ip_is_fragment(ip_hdr(skb))) {
166 if (ip_defrag(net, skb, IP_DEFRAG_CALL_RA_CHAIN))
167 return true;
168 }
169 if (last) {
170 struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
171 if (skb2)
172 raw_rcv(last, skb2);
173 }
174 last = sk;
175 }
176 }
177
178 if (last) {
179 raw_rcv(last, skb);
180 return true;
181 }
182 return false;
183 }
184
185 INDIRECT_CALLABLE_DECLARE(int udp_rcv(struct sk_buff *));
186 INDIRECT_CALLABLE_DECLARE(int tcp_v4_rcv(struct sk_buff *));
ip_protocol_deliver_rcu(struct net * net,struct sk_buff * skb,int protocol)187 void ip_protocol_deliver_rcu(struct net *net, struct sk_buff *skb, int protocol)
188 {
189 const struct net_protocol *ipprot;
190 int raw, ret;
191
192 resubmit:
193 raw = raw_local_deliver(skb, protocol);
194
195 ipprot = rcu_dereference(inet_protos[protocol]);
196 if (ipprot) {
197 if (!ipprot->no_policy) {
198 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
199 kfree_skb_reason(skb,
200 SKB_DROP_REASON_XFRM_POLICY);
201 return;
202 }
203 nf_reset_ct(skb);
204 }
205 ret = INDIRECT_CALL_2(ipprot->handler, tcp_v4_rcv, udp_rcv,
206 skb);
207 if (ret < 0) {
208 protocol = -ret;
209 goto resubmit;
210 }
211 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
212 } else {
213 if (!raw) {
214 if (xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
215 __IP_INC_STATS(net, IPSTATS_MIB_INUNKNOWNPROTOS);
216 icmp_send(skb, ICMP_DEST_UNREACH,
217 ICMP_PROT_UNREACH, 0);
218 }
219 kfree_skb_reason(skb, SKB_DROP_REASON_IP_NOPROTO);
220 } else {
221 __IP_INC_STATS(net, IPSTATS_MIB_INDELIVERS);
222 consume_skb(skb);
223 }
224 }
225 }
226
ip_local_deliver_finish(struct net * net,struct sock * sk,struct sk_buff * skb)227 static int ip_local_deliver_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
228 {
229 if (unlikely(skb_orphan_frags_rx(skb, GFP_ATOMIC))) {
230 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
231 kfree_skb_reason(skb, SKB_DROP_REASON_NOMEM);
232 return 0;
233 }
234
235 skb_clear_delivery_time(skb);
236 __skb_pull(skb, skb_network_header_len(skb));
237
238 rcu_read_lock();
239 ip_protocol_deliver_rcu(net, skb, ip_hdr(skb)->protocol);
240 rcu_read_unlock();
241
242 return 0;
243 }
244
245 /*
246 * Deliver IP Packets to the higher protocol layers.
247 */
ip_local_deliver(struct sk_buff * skb)248 int ip_local_deliver(struct sk_buff *skb)
249 {
250 /*
251 * Reassemble IP fragments.
252 */
253 struct net *net = dev_net(skb->dev);
254
255 if (ip_is_fragment(ip_hdr(skb))) {
256 if (ip_defrag(net, skb, IP_DEFRAG_LOCAL_DELIVER))
257 return 0;
258 }
259
260 return NF_HOOK(NFPROTO_IPV4, NF_INET_LOCAL_IN,
261 net, NULL, skb, skb->dev, NULL,
262 ip_local_deliver_finish);
263 }
264 EXPORT_SYMBOL(ip_local_deliver);
265
ip_rcv_options(struct sk_buff * skb,struct net_device * dev)266 static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev)
267 {
268 struct ip_options *opt;
269 const struct iphdr *iph;
270
271 /* It looks as overkill, because not all
272 IP options require packet mangling.
273 But it is the easiest for now, especially taking
274 into account that combination of IP options
275 and running sniffer is extremely rare condition.
276 --ANK (980813)
277 */
278 if (skb_cow(skb, skb_headroom(skb))) {
279 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INDISCARDS);
280 goto drop;
281 }
282
283 iph = ip_hdr(skb);
284 opt = &(IPCB(skb)->opt);
285 opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
286
287 if (ip_options_compile(dev_net(dev), opt, skb)) {
288 __IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
289 goto drop;
290 }
291
292 if (unlikely(opt->srr)) {
293 struct in_device *in_dev = __in_dev_get_rcu(dev);
294
295 if (in_dev) {
296 if (!IN_DEV_SOURCE_ROUTE(in_dev)) {
297 if (IN_DEV_LOG_MARTIANS(in_dev))
298 net_info_ratelimited("source route option %pI4 -> %pI4\n",
299 &iph->saddr,
300 &iph->daddr);
301 goto drop;
302 }
303 }
304
305 if (ip_options_rcv_srr(skb, dev))
306 goto drop;
307 }
308
309 return false;
310 drop:
311 return true;
312 }
313
ip_can_use_hint(const struct sk_buff * skb,const struct iphdr * iph,const struct sk_buff * hint)314 static bool ip_can_use_hint(const struct sk_buff *skb, const struct iphdr *iph,
315 const struct sk_buff *hint)
316 {
317 return hint && !skb_dst(skb) && ip_hdr(hint)->daddr == iph->daddr &&
318 ip_hdr(hint)->tos == iph->tos;
319 }
320
321 int tcp_v4_early_demux(struct sk_buff *skb);
322 int udp_v4_early_demux(struct sk_buff *skb);
ip_rcv_finish_core(struct net * net,struct sk_buff * skb,struct net_device * dev,const struct sk_buff * hint)323 static int ip_rcv_finish_core(struct net *net,
324 struct sk_buff *skb, struct net_device *dev,
325 const struct sk_buff *hint)
326 {
327 const struct iphdr *iph = ip_hdr(skb);
328 struct rtable *rt;
329 int drop_reason;
330
331 if (ip_can_use_hint(skb, iph, hint)) {
332 drop_reason = ip_route_use_hint(skb, iph->daddr, iph->saddr,
333 ip4h_dscp(iph), dev, hint);
334 if (unlikely(drop_reason))
335 goto drop_error;
336 }
337
338 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
339 if (READ_ONCE(net->ipv4.sysctl_ip_early_demux) &&
340 !skb_dst(skb) &&
341 !skb->sk &&
342 !ip_is_fragment(iph)) {
343 switch (iph->protocol) {
344 case IPPROTO_TCP:
345 if (READ_ONCE(net->ipv4.sysctl_tcp_early_demux)) {
346 tcp_v4_early_demux(skb);
347
348 /* must reload iph, skb->head might have changed */
349 iph = ip_hdr(skb);
350 }
351 break;
352 case IPPROTO_UDP:
353 if (READ_ONCE(net->ipv4.sysctl_udp_early_demux)) {
354 drop_reason = udp_v4_early_demux(skb);
355 if (unlikely(drop_reason))
356 goto drop_error;
357 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
358
359 /* must reload iph, skb->head might have changed */
360 iph = ip_hdr(skb);
361 }
362 break;
363 }
364 }
365
366 /*
367 * Initialise the virtual path cache for the packet. It describes
368 * how the packet travels inside Linux networking.
369 */
370 if (!skb_valid_dst(skb)) {
371 drop_reason = ip_route_input_noref(skb, iph->daddr, iph->saddr,
372 ip4h_dscp(iph), dev);
373 if (unlikely(drop_reason))
374 goto drop_error;
375 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
376 } else {
377 struct in_device *in_dev = __in_dev_get_rcu(dev);
378
379 if (in_dev && IN_DEV_ORCONF(in_dev, NOPOLICY))
380 IPCB(skb)->flags |= IPSKB_NOPOLICY;
381 }
382
383 #ifdef CONFIG_IP_ROUTE_CLASSID
384 if (unlikely(skb_dst(skb)->tclassid)) {
385 struct ip_rt_acct *st = this_cpu_ptr(ip_rt_acct);
386 u32 idx = skb_dst(skb)->tclassid;
387 st[idx&0xFF].o_packets++;
388 st[idx&0xFF].o_bytes += skb->len;
389 st[(idx>>16)&0xFF].i_packets++;
390 st[(idx>>16)&0xFF].i_bytes += skb->len;
391 }
392 #endif
393
394 if (iph->ihl > 5 && ip_rcv_options(skb, dev))
395 goto drop;
396
397 rt = skb_rtable(skb);
398 if (rt->rt_type == RTN_MULTICAST) {
399 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INMCAST, skb->len);
400 } else if (rt->rt_type == RTN_BROADCAST) {
401 __IP_UPD_PO_STATS(net, IPSTATS_MIB_INBCAST, skb->len);
402 } else if (skb->pkt_type == PACKET_BROADCAST ||
403 skb->pkt_type == PACKET_MULTICAST) {
404 struct in_device *in_dev = __in_dev_get_rcu(dev);
405
406 /* RFC 1122 3.3.6:
407 *
408 * When a host sends a datagram to a link-layer broadcast
409 * address, the IP destination address MUST be a legal IP
410 * broadcast or IP multicast address.
411 *
412 * A host SHOULD silently discard a datagram that is received
413 * via a link-layer broadcast (see Section 2.4) but does not
414 * specify an IP multicast or broadcast destination address.
415 *
416 * This doesn't explicitly say L2 *broadcast*, but broadcast is
417 * in a way a form of multicast and the most common use case for
418 * this is 802.11 protecting against cross-station spoofing (the
419 * so-called "hole-196" attack) so do it for both.
420 */
421 if (in_dev &&
422 IN_DEV_ORCONF(in_dev, DROP_UNICAST_IN_L2_MULTICAST)) {
423 drop_reason = SKB_DROP_REASON_UNICAST_IN_L2_MULTICAST;
424 goto drop;
425 }
426 }
427
428 return NET_RX_SUCCESS;
429
430 drop:
431 kfree_skb_reason(skb, drop_reason);
432 return NET_RX_DROP;
433
434 drop_error:
435 if (drop_reason == SKB_DROP_REASON_IP_RPFILTER)
436 __NET_INC_STATS(net, LINUX_MIB_IPRPFILTER);
437 goto drop;
438 }
439
ip_rcv_finish(struct net * net,struct sock * sk,struct sk_buff * skb)440 static int ip_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
441 {
442 struct net_device *dev = skb->dev;
443 int ret;
444
445 /* if ingress device is enslaved to an L3 master device pass the
446 * skb to its handler for processing
447 */
448 skb = l3mdev_ip_rcv(skb);
449 if (!skb)
450 return NET_RX_SUCCESS;
451
452 ret = ip_rcv_finish_core(net, skb, dev, NULL);
453 if (ret != NET_RX_DROP)
454 ret = dst_input(skb);
455 return ret;
456 }
457
458 /*
459 * Main IP Receive routine.
460 */
ip_rcv_core(struct sk_buff * skb,struct net * net)461 static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
462 {
463 const struct iphdr *iph;
464 int drop_reason;
465 u32 len;
466
467 /* When the interface is in promisc. mode, drop all the crap
468 * that it receives, do not try to analyse it.
469 */
470 if (skb->pkt_type == PACKET_OTHERHOST) {
471 dev_core_stats_rx_otherhost_dropped_inc(skb->dev);
472 drop_reason = SKB_DROP_REASON_OTHERHOST;
473 goto drop;
474 }
475
476 __IP_UPD_PO_STATS(net, IPSTATS_MIB_IN, skb->len);
477
478 skb = skb_share_check(skb, GFP_ATOMIC);
479 if (!skb) {
480 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
481 goto out;
482 }
483
484 drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
485 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
486 goto inhdr_error;
487
488 iph = ip_hdr(skb);
489
490 /*
491 * RFC1122: 3.2.1.2 MUST silently discard any IP frame that fails the checksum.
492 *
493 * Is the datagram acceptable?
494 *
495 * 1. Length at least the size of an ip header
496 * 2. Version of 4
497 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums]
498 * 4. Doesn't have a bogus length
499 */
500
501 if (iph->ihl < 5 || iph->version != 4)
502 goto inhdr_error;
503
504 BUILD_BUG_ON(IPSTATS_MIB_ECT1PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_1);
505 BUILD_BUG_ON(IPSTATS_MIB_ECT0PKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_ECT_0);
506 BUILD_BUG_ON(IPSTATS_MIB_CEPKTS != IPSTATS_MIB_NOECTPKTS + INET_ECN_CE);
507 __IP_ADD_STATS(net,
508 IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
509 max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
510
511 if (!pskb_may_pull(skb, iph->ihl*4))
512 goto inhdr_error;
513
514 iph = ip_hdr(skb);
515
516 if (unlikely(ip_fast_csum((u8 *)iph, iph->ihl)))
517 goto csum_error;
518
519 len = iph_totlen(skb, iph);
520 if (skb->len < len) {
521 drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
522 __IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
523 goto drop;
524 } else if (len < (iph->ihl*4))
525 goto inhdr_error;
526
527 /* Our transport medium may have padded the buffer out. Now we know it
528 * is IP we can trim to the true length of the frame.
529 * Note this now means skb->len holds ntohs(iph->tot_len).
530 */
531 if (pskb_trim_rcsum(skb, len)) {
532 __IP_INC_STATS(net, IPSTATS_MIB_INDISCARDS);
533 goto drop;
534 }
535
536 iph = ip_hdr(skb);
537 skb->transport_header = skb->network_header + iph->ihl*4;
538
539 /* Remove any debris in the socket control block */
540 memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
541 IPCB(skb)->iif = skb->skb_iif;
542
543 /* Must drop socket now because of tproxy. */
544 if (!skb_sk_is_prefetched(skb))
545 skb_orphan(skb);
546
547 return skb;
548
549 csum_error:
550 drop_reason = SKB_DROP_REASON_IP_CSUM;
551 __IP_INC_STATS(net, IPSTATS_MIB_CSUMERRORS);
552 inhdr_error:
553 if (drop_reason == SKB_DROP_REASON_NOT_SPECIFIED)
554 drop_reason = SKB_DROP_REASON_IP_INHDR;
555 __IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
556 drop:
557 kfree_skb_reason(skb, drop_reason);
558 out:
559 return NULL;
560 }
561
562 /*
563 * IP receive entry point
564 */
ip_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)565 int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
566 struct net_device *orig_dev)
567 {
568 struct net *net = dev_net(dev);
569
570 skb = ip_rcv_core(skb, net);
571 if (skb == NULL)
572 return NET_RX_DROP;
573
574 return NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING,
575 net, NULL, skb, dev, NULL,
576 ip_rcv_finish);
577 }
578
ip_sublist_rcv_finish(struct list_head * head)579 static void ip_sublist_rcv_finish(struct list_head *head)
580 {
581 struct sk_buff *skb, *next;
582
583 list_for_each_entry_safe(skb, next, head, list) {
584 skb_list_del_init(skb);
585 dst_input(skb);
586 }
587 }
588
ip_extract_route_hint(const struct net * net,struct sk_buff * skb,int rt_type)589 static struct sk_buff *ip_extract_route_hint(const struct net *net,
590 struct sk_buff *skb, int rt_type)
591 {
592 if (fib4_has_custom_rules(net) || rt_type == RTN_BROADCAST ||
593 IPCB(skb)->flags & IPSKB_MULTIPATH)
594 return NULL;
595
596 return skb;
597 }
598
ip_list_rcv_finish(struct net * net,struct list_head * head)599 static void ip_list_rcv_finish(struct net *net, struct list_head *head)
600 {
601 struct sk_buff *skb, *next, *hint = NULL;
602 struct dst_entry *curr_dst = NULL;
603 LIST_HEAD(sublist);
604
605 list_for_each_entry_safe(skb, next, head, list) {
606 struct net_device *dev = skb->dev;
607 struct dst_entry *dst;
608
609 skb_list_del_init(skb);
610 /* if ingress device is enslaved to an L3 master device pass the
611 * skb to its handler for processing
612 */
613 skb = l3mdev_ip_rcv(skb);
614 if (!skb)
615 continue;
616 if (ip_rcv_finish_core(net, skb, dev, hint) == NET_RX_DROP)
617 continue;
618
619 dst = skb_dst(skb);
620 if (curr_dst != dst) {
621 hint = ip_extract_route_hint(net, skb,
622 dst_rtable(dst)->rt_type);
623
624 /* dispatch old sublist */
625 if (!list_empty(&sublist))
626 ip_sublist_rcv_finish(&sublist);
627 /* start new sublist */
628 INIT_LIST_HEAD(&sublist);
629 curr_dst = dst;
630 }
631 list_add_tail(&skb->list, &sublist);
632 }
633 /* dispatch final sublist */
634 ip_sublist_rcv_finish(&sublist);
635 }
636
ip_sublist_rcv(struct list_head * head,struct net_device * dev,struct net * net)637 static void ip_sublist_rcv(struct list_head *head, struct net_device *dev,
638 struct net *net)
639 {
640 NF_HOOK_LIST(NFPROTO_IPV4, NF_INET_PRE_ROUTING, net, NULL,
641 head, dev, NULL, ip_rcv_finish);
642 ip_list_rcv_finish(net, head);
643 }
644
645 /* Receive a list of IP packets */
ip_list_rcv(struct list_head * head,struct packet_type * pt,struct net_device * orig_dev)646 void ip_list_rcv(struct list_head *head, struct packet_type *pt,
647 struct net_device *orig_dev)
648 {
649 struct net_device *curr_dev = NULL;
650 struct net *curr_net = NULL;
651 struct sk_buff *skb, *next;
652 LIST_HEAD(sublist);
653
654 list_for_each_entry_safe(skb, next, head, list) {
655 struct net_device *dev = skb->dev;
656 struct net *net = dev_net(dev);
657
658 skb_list_del_init(skb);
659 skb = ip_rcv_core(skb, net);
660 if (skb == NULL)
661 continue;
662
663 if (curr_dev != dev || curr_net != net) {
664 /* dispatch old sublist */
665 if (!list_empty(&sublist))
666 ip_sublist_rcv(&sublist, curr_dev, curr_net);
667 /* start new sublist */
668 INIT_LIST_HEAD(&sublist);
669 curr_dev = dev;
670 curr_net = net;
671 }
672 list_add_tail(&skb->list, &sublist);
673 }
674 /* dispatch final sublist */
675 if (!list_empty(&sublist))
676 ip_sublist_rcv(&sublist, curr_dev, curr_net);
677 }
678