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